namespace: change -> git.grassecon.net/kamikazechaser/vise

This reverts commit b55edd2678.

.gitignore

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+examples/**/*.bin
+examples/**/*.txt

LICENSE

@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
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+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<https://www.gnu.org/licenses/>.

Makefile

@@ -0,0 +1,15 @@
+examples: profile session helloworld validate
+
+.PHONY: examples
+
+profile:
+	bash examples/compile.bash examples/profile
+
+session:
+	bash examples/compile.bash examples/session
+
+helloworld:
+	bash examples/compile.bash examples/helloworld
+
+validate:
+	bash examples/compile.bash examples/validate

README.md

@@ -1,27 +1,63 @@
-# festive: A Constrained Size Output Virtual Machine
+# vise: A Constrained Size Output Virtual Machine
 
 An attempt at defining a small VM to handle menu interaction for size-constrained clients and servers.
 
+
+## Rationale
+
 Original motivation was to create a simple templating renderer for USSD clients, combined with an agnostic data-retrieval reference that may conceal any level of complexity.
 
 
+## Features
+
+### Implemented
+
+* Define and enforce max output size for every individual output.
+* Allow one single data entry to fill remaining available size capacity.
+* An assembly-like mini-language to define:
+    - external code execution.
+    - input validation and routing.
+    - menu definitions.
+    - flow control.
+    - exception handling.
+* templated output from results of external code execution.
+* generate and navigate pages where data symbol contents are too long to display on a single page.
+* pluggable function design for handling external code execution calls.
+
+
+### Pending
+
+* Node Walking Audit Tool (NWAT) to ensure all nodes produce output within constraints.
+* Input generator engine for the NWAT.
+* State error flag debugger representation, builtin as well as user-defined.
+* Stepwise debug view on log/stderr of state mutations.
+* Toolset to assist bootstrapping/recovering (failed) state from spec.
+
+
+### Possibly useful
+
+* Breakpoints.
+* Key/value database reference example.
+* Same-page catch with dedicated error string to prepend to template
+
 
 ## Opcodes
 
-The VM defines the following opcode symbols:
+The VM defines the following opcode symbols, alphabetically:
 
-* `CATCH <symbol> <signal>` - Jump to symbol if signal is set (see `signals` below).
-* `CROAK <signal>` - Clear state and restart execution from top if signal is set (see `signals` below).
-* `LOAD <symbol> <size>` - Execute the code symbol `symbol` and cache the data, constrained to the given `size`. Can be exposed with `MAP` within scope, 
-* `RELOAD <symbol>` - Execute a code symbol already loaded by `LOAD` and cache the data, constrained to the previously given `size` for the same symbol. 
-* `MAP <symbol>` - Expose a code symbol previously loaded by `LOAD` to the rendering client. Roughly corresponds to the `global` directive in Python.
-* `MOVE <symbol>` - Create a new execution frame, invalidating all previous `MAP` calls. More detailed: After a `MOVE` call, a `BACK` call will return to the same execution frame, with the same symbols available, but all `MAP` calls will have to be repeated.
+* `CATCH <symbol> <signal>` - Jump to symbol if signal is set (see `signals` below). If match, has same side-effect as move.
+* `CROAK <signal>` - Clear state and restart execution from top if signal is set (see `signals` below). If match, has same side-effect as move.
 * `HALT` - Stop execution. The remaining bytecode (typically, the routing code for the node) is returned to the invoking function.
 * `INCMP <arg> <symbol>` - Compare registered input to `arg`. If match, it has the same side-effects as `MOVE`. In addition, any consecutive `INCMP` matches will be ignored until `HALT` is called.
-* `MSIZE <max> <min>` - Set min and max display size of menu part to `num` bytes.
-* `MOUT <choice> <display>` - Add menu display entry. Each entry should have a matching `INCMP` whose `arg` matches `choice`. `display` is a descriptive text of the menu item.
+* `LOAD <symbol> <size>` - Execute the code symbol `symbol` and cache the data, constrained to the given `size`. Can be exposed with `MAP` within scope.  See "External code" below.
+* `MAP <symbol>` - Expose a code symbol previously loaded by `LOAD` to the rendering client. Roughly corresponds to the `global` directive in Python.
 * `MNEXT <choice> <display>` - Define how to display the choice for advancing when browsing menu.
+* `MOUT <choice> <display>` - Add menu display entry. Each entry should have a matching `INCMP` whose `arg` matches `choice`. `display` is a descriptive text of the menu item.
+* `MOVE <symbol>` - Create a new execution frame, invalidating all previous `MAP` calls.
 * `MPREV <choice> <display>` - Define how to display the choice for returning when browsing menu.
+* `MSEP` -  **Not yet implemented**. Marker for menu page separation. Incompatible with browseable nodes.
+* `MSIZE <max> <min>` - **Not yet implemented**. Set min and max display size of menu part to `num` bytes.
+* `RELOAD <symbol>` - Execute a code symbol already loaded by `LOAD` and cache the data, constrained to the previously given `size` for the same symbol. See "External code" below.
 
 
 ### External code
@@ -34,6 +70,8 @@ Loaded symbols are not automatically exposed to the rendering client. To expose
 
 The associated content of loaded symbols may be refreshed using the `RELOAD` opcode. `RELOAD` only works within the same constraints as `MAP`. However, updated content must be available even if a `MAP` precedes a `RELOAD` within the same frame.
 
+Methods handling `LOAD` symbols have the client input available to them.
+
 
 ### External symbol optimizations
 
@@ -55,6 +93,8 @@ The signal flag arguments should only set a single flag to be tested. If more th
 
 First 8 flags are reserved and used for internal VM operations.
 
+When a signal is caught, the *bytecode buffer is flushed* before the target symbol code is loaded.
+
 
 ### Avoid duplicate menu items
 
@@ -79,20 +119,19 @@ To assist with menu creation, a few batch operation symbols have been made avail
 
 The fixed-size output is generated using a templating language, and a combination of one or more _max size_ properties, and an optional _sink_ property that will attempt to consume all remaining capacity of the rendered template.
 
-For example, in this example
+In this example
 
 - `maxOutputSize` is 256 bytes long.
 - `template` is 120 bytes long.
 - param `one` has max size 10 but uses 5.
 - param `two` has max size 20 but uses 12.
 - param `three` is a _sink_.
+- rendered menu is 15 bytes long.
 
-The renderer may use up to `256 - 120 - 5 - 12 = 119` bytes from the _sink_ when rendering the output.
+The renderer may use up to `256 - 120 - 5 - 12 - 15 = 104` bytes from the _sink_ when rendering the output.
 
 
-### Menu rendering
-
-The menu is appended to the template output.
+### Menu browsing
 
 A max size can be set for the menu, which will count towards the space available for the _template sink_.
 
@@ -117,6 +156,8 @@ Multipage outputs, like listings, are handled using the _sink_ output constraint
 
 ### Languages support
 
+**Not yet implemented**
+
 Language for rendering is determined at the top-level state.
 
 Lookups dependent on language are prefixed by either `ISO 639-1` or `ISO 639-3` language codes, followed by `:`.
@@ -140,19 +181,19 @@ Currently the following rules apply for encoding in version `0`:
 
 ## Reference implementation
 
-This repository provides a `golang` reference implementation for the `festive` concept.
-
-In this reference implementation some constraints apply
+This repository provides a `golang` reference implementation for the `vise` concept.
 
 
 ### Structure
 
-_TODO_: `state` will be separated into `cache` and `session`.
-
-- `vm`: Defines instructions, and applies transformations according to the instructions.
-- `state`: Holds the code cache, contents cache aswell as error tates from code execution.
-- `resource`: Retrieves data and bytecode from external symbols, and retrieves and renders templates.
+- `asm`: Assembly parser and compiler.
+- `cache`: Holds and manages all loaded content.
 - `engine`: Outermost interface. Orchestrates execution of bytecode against input. 
+- `persist`: Interface and reference implementation of `state` and `cache` persistence across asynchronous vm executions.
+- `render`: Renders menu and templates, and enforces output size constraints.
+- `resource`: Retrieves data and bytecode from external symbols, and retrieves templates.
+- `state`: Holds the bytecode buffer, error states and navigation states.
+- `vm`: Defines instructions, and applies transformations according to the instructions.
 
 
 ### Template rendering
@@ -162,6 +203,28 @@ Template rendering is done using the `text/template` faciilty in the `golang` st
 It expects all replacement symbols to be available at time of rendering, and has no tolerance for missing ones.
 
 
+## Runtime engine
+
+The runtime engine:
+
+* Validates client input
+* Runs VM with client input
+* Renders result
+* Restarts execution from top if the vm has nothing more to do.
+
+There are two flavors of the engine:
+
+* `engine.Loop` - class used for continuous, in-memory interaction with the vm (e.g. terminal).
+* `engine.RunPersisted` - method which combines single vm executions with persisted state (e.g. http).
+
+
+### Client identification
+
+The `engine.Config` struct defines a property `SessionId` which is added to the `context.Context` passed through entire engine vm call roundtrip.
+
+This is used to identify the caller, and thus defines a top-level storage key under which data entries should be retrieved.
+
+
 ## Bytecode examples
 
 (Minimal, WIP)
@@ -180,7 +243,7 @@ It expects all replacement symbols to be available at time of rendering, and has
 
 ## Assembly examples
 
-See `testdata/*.fst`
+See `testdata/*.vis`
 
 
 ## Development tools
@@ -190,14 +253,14 @@ Located in the `dev/` directory.
 
 ### Test data generation
 
-`go run ./dev/testdata/ <directory>`
+`go run ./dev/gendata/ <directory>`
 
 Outputs bytecodes and templates for test data scenarios used in `engine` unit tests.
 
 
 ### Interactive runner
 
-`go run ./dev [-d <data_directory>] [--root <root_symbol>]`
+`go run ./dev/interactive [-d <data_directory>] [--root <root_symbol>] [--session-id <session_id>]`
 
 Creates a new interactive session using `engine.DefaultEngine`, starting execution at symbol `root_symbol`
 
@@ -207,6 +270,8 @@ If `data_directory` is not set, current directory will be used.
 
 if `root_symbol` is not set, the symbol `root` will be used.
 
+if `session_id` is set, mutable data will be stored and retrieved keyed by the given identifer (if implemented).
+
 
 ### Assembler
 
@@ -221,3 +286,20 @@ Will output bytecode on STDOUT generated from a valid assembly file.
 
 Will list all the instructions on STDOUT from a valid binary file.
 
+
+## Interactive case examples
+
+Found in `examples/`.
+
+Be sure to `make examples` before running them.
+
+Can be run with e.g. `go run ./examples/<case> [...]`
+
+The available options are the same as for the `dev/interactive` tool.
+
+Contents of the case directory:
+
+* `*.vis` - assembly code.
+* `*.bin` - bytecode for each node symbol (only available after make).
+* `*.txt.orig` - default contents of a single data entry.
+* `*.txt` - current contents of a single data entry (only available after make).

asm/asm.go

@@ -13,20 +13,21 @@ import (
 	"github.com/alecthomas/participle/v2"
 	"github.com/alecthomas/participle/v2/lexer"
 
-	"git.defalsify.org/festive/vm"
+	"git.grassecon.net/kamikazechaser/vise/vm"
 )
 
-
+// Asm assembles bytecode from the vise assembly mini-language.
 type Asm struct {
 	Instructions []*Instruction `@@*`
 }
 
+// Arg holds all parsed argument elements of a single line of assembly code.
 type Arg struct {
-	Sym *string `(@Sym Whitespace?)?`
-	Size *uint32 `(@Size Whitespace?)?`
-	Flag *uint8 `(@Size Whitespace?)?`
+	Sym      *string `(@Sym Whitespace?)?`
+	Size     *uint32 `(@Size Whitespace?)?`
+	Flag     *uint8  `(@Size Whitespace?)?`
 	Selector *string `(@Sym Whitespace?)?`
-	Desc *string `(Quote ((@Sym | @Size) @Whitespace?)+ Quote Whitespace?)?`
+	Desc     *string `(Quote ((@Sym | @Size) @Whitespace?)+ Quote Whitespace?)?`
 }
 
 func flush(b *bytes.Buffer, w io.Writer) (int, error) {
@@ -91,8 +92,13 @@ func parseTwoSym(b *bytes.Buffer, arg Arg) (int, error) {
 		selector = strconv.FormatUint(uint64(*arg.Size), 10)
 		sym = *arg.Selector
 	} else if arg.Selector != nil {
-		sym = *arg.Sym
-		selector = *arg.Selector
+		if *arg.Sym == "*" {
+			sym = *arg.Selector
+			selector = *arg.Sym
+		} else {
+			sym = *arg.Sym
+			selector = *arg.Selector
+		}
 	}
 
 	n, err := writeSym(b, selector)
@@ -156,12 +162,12 @@ func parseOne(op vm.Opcode, instruction *Instruction, w io.Writer) (int, error)
 	a := instruction.OpArg
 	var n_buf int
 	var n_out int
-	
+
 	b := bytes.NewBuffer(nil)
 
 	n, err := writeOpcode(b, op)
 	n_buf += n
-	if  err != nil {
+	if err != nil {
 		return n_out, err
 	}
 
@@ -212,9 +218,9 @@ func parseOne(op vm.Opcode, instruction *Instruction, w io.Writer) (int, error)
 	n, err = writeSym(b, *a.Sym)
 	n_buf += n
 	return flush(b, w)
-
 }
 
+// String implements the String interface.
 func (a Arg) String() string {
 	s := "[Arg]"
 	if a.Sym != nil {
@@ -236,12 +242,14 @@ func (a Arg) String() string {
 	return fmt.Sprintf(s)
 }
 
+// Instruction represents one full line of assembly code.
 type Instruction struct {
-	OpCode string `@Ident`
-	OpArg Arg `(Whitespace @@)?`
+	OpCode  string `@Ident`
+	OpArg   Arg    `(Whitespace @@)?`
 	Comment string `Comment? EOL`
 }
 
+// String implement the String interface.
 func (i Instruction) String() string {
 	return fmt.Sprintf("%s %s", i.OpCode, i.OpArg)
 }
@@ -251,7 +259,7 @@ var (
 		{"Comment", `(?:#)[^\n]*`},
 		{"Ident", `^[A-Z]+`},
 		{"Size", `[0-9]+`},
-		{"Sym", `[a-zA-Z_][a-zA-Z0-9_]*`},
+		{"Sym", `[a-zA-Z_\*\.][a-zA-Z0-9_]*`},
 		{"Whitespace", `[ \t]+`},
 		{"EOL", `[\n\r]+`},
 		{"Quote", `["']`},
@@ -264,7 +272,7 @@ var (
 
 func numSize(n uint32) int {
 	v := math.Log2(float64(n))
-	return int((v  / 8) + 1)
+	return int((v / 8) + 1)
 }
 
 func writeOpcode(w *bytes.Buffer, op vm.Opcode) (int, error) {
@@ -293,6 +301,9 @@ func writeDisplay(w *bytes.Buffer, s string) (int, error) {
 	return w.WriteString(s)
 }
 func writeSize(w *bytes.Buffer, n uint32) (int, error) {
+	if n == 0 {
+		return w.Write([]byte{0x01, 0x00})
+	}
 	bn := [4]byte{}
 	sz := numSize(n)
 	if sz > 4 {
@@ -300,32 +311,35 @@ func writeSize(w *bytes.Buffer, n uint32) (int, error) {
 	}
 	w.Write([]byte{byte(sz)})
 	binary.BigEndian.PutUint32(bn[:], n)
-	c := 4-sz
+	c := 4 - sz
 	return w.Write(bn[c:])
 }
 
+// Batcher handles assembly commands that generates multiple instructions, such as menu navigation commands.
 type Batcher struct {
 	menuProcessor MenuProcessor
-	inMenu bool
+	inMenu        bool
 }
 
+// NewBatcher creates a new Batcher objcet.
 func NewBatcher(mp MenuProcessor) Batcher {
 	return Batcher{
 		menuProcessor: NewMenuProcessor(),
 	}
 }
 
-func(bt *Batcher) MenuExit(w io.Writer) (int, error) {
+// MenuExit generates the instructions for the batch and writes them to the given io.Writer.
+func (bt *Batcher) MenuExit(w io.Writer) (int, error) {
 	if !bt.inMenu {
 		return 0, nil
 	}
 	bt.inMenu = false
 	b := bt.menuProcessor.ToLines()
-	log.Printf("tolines %v", b)
 	return w.Write(b)
 }
 
-func(bt *Batcher) MenuAdd(w io.Writer, code string, arg Arg) (int, error) {
+// MenuAdd adds a new menu instruction to the batcher.
+func (bt *Batcher) MenuAdd(w io.Writer, code string, arg Arg) (int, error) {
 	bt.inMenu = true
 	var selector string
 	var sym string
@@ -345,10 +359,12 @@ func(bt *Batcher) MenuAdd(w io.Writer, code string, arg Arg) (int, error) {
 	return 0, err
 }
 
-func(bt *Batcher) Exit(w io.Writer) (int, error) {
+// Exit is a synonym for MenuExit
+func (bt *Batcher) Exit(w io.Writer) (int, error) {
 	return bt.MenuExit(w)
 }
 
+// Parse one or more lines of assembly code, and write assembled bytecode to the provided writer.
 func Parse(s string, w io.Writer) (int, error) {
 	rd := strings.NewReader(s)
 	ast, err := asmParser.Parse("file", rd)
@@ -356,9 +372,7 @@ func Parse(s string, w io.Writer) (int, error) {
 		return 0, err
 	}
 
-	batch := Batcher{
-		
-	}
+	batch := Batcher{}
 
 	var rn int
 	for _, v := range ast.Instructions {

asm/asm_test.go

@@ -7,10 +7,9 @@ import (
 	"log"
 	"testing"
 
-	"git.defalsify.org/festive/vm"
+	"git.grassecon.net/kamikazechaser/vise/vm"
 )
 
-
 func TestParserInit(t *testing.T) {
 	var b []byte
 	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
@@ -236,7 +235,7 @@ func TestParserWriteMultiple(t *testing.T) {
 	if n != n_expect {
 		t.Fatalf("expected total %v bytes output, got %v", n_expect, n)
 	}
-	
+
 	rb := r.Bytes()
 	if !bytes.Equal(rb, r_expect) {
 		t.Fatalf("expected result:\n\t%v, got:\n\t%x", r_expect_hex, rb)

asm/doc.go

@@ -0,0 +1,2 @@
+// Package asm parses and compiles vise assembly code to bytecode.
+package asm

asm/menu.go

@@ -0,0 +1,94 @@
+package asm
+
+import (
+	"fmt"
+
+	"git.grassecon.net/kamikazechaser/vise/vm"
+)
+
+// BatchCode defines quasi-opcodes that expand to mulitple individual vm instructions.
+type BatchCode uint16
+
+const (
+	_MENU_OFFSET  = 256
+	MENU_DOWN     = _MENU_OFFSET
+	MENU_UP       = _MENU_OFFSET + 1
+	MENU_NEXT     = _MENU_OFFSET + 2
+	MENU_PREVIOUS = _MENU_OFFSET + 3
+)
+
+var (
+	batchCode = map[string]BatchCode{
+		"DOWN":     MENU_DOWN,
+		"UP":       MENU_UP,
+		"NEXT":     MENU_NEXT,
+		"PREVIOUS": MENU_PREVIOUS,
+	}
+)
+
+type menuItem struct {
+	code    BatchCode
+	choice  string
+	display string
+	target  string
+}
+
+// MenuProcessor handles code lines with BatchCode quasi-opcodes that control menu generation.
+//
+// It creates vm instructions for display of menu and handling of input on either size of a vm.HALT instruction.
+type MenuProcessor struct {
+	items []menuItem
+	size  uint32
+}
+
+// NewMenuProcessor creates a new MenuProcessor object.
+func NewMenuProcessor() MenuProcessor {
+	return MenuProcessor{}
+}
+
+// Add a menu batch instruction to be processed.
+//
+// Instructions will be rendered in the order in which they have been added.
+func (mp *MenuProcessor) Add(bop string, choice string, display string, target string) error {
+	bopCode := batchCode[bop]
+	if bopCode == 0 {
+		return fmt.Errorf("unknown menu instruction: %v", bop)
+	}
+	if len(target) > 0 && bopCode != MENU_DOWN {
+		return fmt.Errorf("target is only valid for DOWN")
+	}
+	m := menuItem{
+		code:    bopCode,
+		choice:  choice,
+		display: display,
+		target:  target,
+	}
+	mp.items = append(mp.items, m)
+	return nil
+}
+
+// ToLines returns the generated bytecode from the added menu batch instructions.
+func (mp *MenuProcessor) ToLines() []byte {
+	preLines := []byte{}
+	postLines := []byte{}
+
+	for _, v := range mp.items {
+		switch v.code {
+		case MENU_UP:
+			preLines = vm.NewLine(preLines, vm.MOUT, []string{v.choice, v.display}, nil, nil)
+			postLines = vm.NewLine(postLines, vm.INCMP, []string{v.choice, "_"}, nil, nil)
+		case MENU_NEXT:
+			preLines = vm.NewLine(preLines, vm.MNEXT, []string{v.choice, v.display}, nil, nil)
+			postLines = vm.NewLine(postLines, vm.INCMP, []string{v.choice, ">"}, nil, nil)
+		case MENU_PREVIOUS:
+			preLines = vm.NewLine(preLines, vm.MPREV, []string{v.choice, v.display}, nil, nil)
+			postLines = vm.NewLine(postLines, vm.INCMP, []string{v.choice, "<"}, nil, nil)
+		default:
+			preLines = vm.NewLine(preLines, vm.MOUT, []string{v.choice, v.display}, nil, nil)
+			postLines = vm.NewLine(postLines, vm.INCMP, []string{v.choice, v.target}, nil, nil)
+		}
+	}
+
+	preLines = vm.NewLine(preLines, vm.HALT, nil, nil, nil)
+	return append(preLines, postLines...)
+}

asm/menu_test.go

@@ -3,10 +3,9 @@ package asm
 import (
 	"testing"
 
-	"git.defalsify.org/festive/vm"
+	"git.grassecon.net/kamikazechaser/vise/vm"
 )
 
-
 func TestMenuInterpreter(t *testing.T) {
 	m := NewMenuProcessor()
 	err := m.Add("DOWN", "0", "inky", "foo")
@@ -35,11 +34,13 @@ func TestMenuInterpreter(t *testing.T) {
 		t.Fatal(err)
 	}
 	expect := `MOUT 0 "inky"
-MOUT 1 "pinky"
-MOUT 2 "blinky clyde"
+MNEXT 1 "pinky"
+MPREV 2 "blinky clyde"
 MOUT 99 "tinky-winky"
 HALT
 INCMP 0 foo
+INCMP 1 >
+INCMP 2 <
 INCMP 99 _
 `
 	if r != expect {

cache/cache.go

@@ -0,0 +1,190 @@
+package cache
+
+import (
+	"fmt"
+	"log"
+)
+
+// Cache stores loaded content, enforcing size limits and keeping track of size usage.
+type Cache struct {
+	CacheSize uint32 // Total allowed cumulative size of values (not code) in cache
+	CacheUseSize uint32 // Currently used bytes by all values (not code) in cache
+	Cache []map[string]string // All loaded cache items
+	Sizes map[string]uint16 // Size limits for all loaded symbols.
+}
+
+// NewCache creates a new ready-to-use cache object
+func NewCache() *Cache {
+	ca := &Cache{
+		Cache: []map[string]string{make(map[string]string)},
+		Sizes: make(map[string]uint16),
+	}
+	return ca
+}
+
+// WithCacheSize applies a cumulative cache size limitation for all cached items.
+func(ca *Cache) WithCacheSize(cacheSize uint32) *Cache {
+	ca.CacheSize = cacheSize
+	return ca
+}
+
+// Add adds a cache value under a cache symbol key.
+//
+// Also stores the size limitation of for key for later updates.
+//
+// Fails if:
+// - key already defined
+// - value is longer than size limit
+// - adding value exceeds cumulative cache capacity
+func(ca *Cache) Add(key string, value string, sizeLimit uint16) error {
+	if sizeLimit > 0 {
+		l := uint16(len(value))
+		if l > sizeLimit {
+			return fmt.Errorf("value length %v exceeds value size limit %v", l, sizeLimit)
+		}
+	}
+	checkFrame := ca.frameOf(key)
+	if checkFrame > -1 {
+		if checkFrame == len(ca.Cache) - 1 {
+			log.Printf("Ignoring load request on frame that has symbol already loaded")
+			return nil
+		}
+		return fmt.Errorf("key %v already defined in frame %v", key, checkFrame)
+	}
+	var sz uint32
+	if len(value) > 0 {
+		sz = ca.checkCapacity(value)
+		if sz == 0 {
+			return fmt.Errorf("Cache capacity exceeded %v of %v", ca.CacheUseSize + sz, ca.CacheSize)
+		}
+	}
+	log.Printf("add key %s value size %v limit %v", key, sz, sizeLimit)
+	ca.Cache[len(ca.Cache)-1][key] = value
+	ca.CacheUseSize += sz
+	ca.Sizes[key] = sizeLimit
+	return nil
+}
+
+// ReservedSize returns the maximum byte size available for the given symbol.
+func(ca *Cache) ReservedSize(key string) (uint16, error) {
+	v, ok := ca.Sizes[key]
+	if !ok {
+		return 0, fmt.Errorf("unknown symbol: %s", key)
+	}
+	return v, nil
+}
+
+// Update sets a new value for an existing key.
+//
+// Uses the size limitation from when the key was added.
+//
+// Fails if:
+// - key not defined
+// - value is longer than size limit
+// - replacing value exceeds cumulative cache capacity
+func(ca *Cache) Update(key string, value string) error {
+	sizeLimit := ca.Sizes[key]
+	if ca.Sizes[key] > 0 {
+		l := uint16(len(value))
+		if l > sizeLimit {
+			return fmt.Errorf("update value length %v exceeds value size limit %v", l, sizeLimit)
+		}
+	}
+	checkFrame := ca.frameOf(key)
+	if checkFrame == -1 {
+		return fmt.Errorf("key %v not defined", key)
+	}
+	r := ca.Cache[checkFrame][key]
+	l := uint32(len(r))
+	ca.Cache[checkFrame][key] = ""
+	ca.CacheUseSize -= l
+	sz := ca.checkCapacity(value)
+	if sz == 0 {
+		baseUseSize := ca.CacheUseSize
+		ca.Cache[checkFrame][key] = r
+		ca.CacheUseSize += l
+		return fmt.Errorf("Cache capacity exceeded %v of %v", baseUseSize + sz, ca.CacheSize)
+	}
+	ca.Cache[checkFrame][key] = value
+	ca.CacheUseSize += uint32(len(value))
+	return nil
+}
+
+// Get the content currently loaded for a single key, loaded at any level.
+//
+// Fails if key has not been loaded.
+func(ca *Cache) Get(key string) (string, error) {
+	i := ca.frameOf(key)
+	r, ok := ca.Cache[i][key]
+	if !ok {
+		return "", fmt.Errorf("unknown key: %s", key)
+	}
+	return r, nil
+}
+
+// Reset flushes all state contents below the top level.
+func(ca *Cache) Reset() {
+	if len(ca.Cache) == 0 {
+		return
+	}
+	ca.Cache = ca.Cache[:1]
+	ca.CacheUseSize = 0
+	return
+}
+
+// Push adds a new level to the cache.
+func (ca *Cache) Push() error {
+	m := make(map[string]string)
+	ca.Cache = append(ca.Cache, m)
+	return nil
+}
+
+// Pop frees the cache of the current level and makes the previous level the current level.
+//
+// Fails if already on top level.
+func (ca *Cache) Pop() error {
+	l := len(ca.Cache)
+	if l == 0 {
+		return fmt.Errorf("already at top level")
+	}
+	l -= 1
+	m := ca.Cache[l]
+	for k, v := range m {
+		sz := len(v)
+		ca.CacheUseSize -= uint32(sz)
+		log.Printf("free frame %v key %v value size %v", l, k, sz)
+	}
+	ca.Cache = ca.Cache[:l]
+	//ca.resetCurrent()
+	return nil
+}
+
+// Check returns true if a key already exists in the cache.
+func(ca *Cache) Check(key string) bool {
+	return ca.frameOf(key) == -1
+}
+
+// bytes that will be added to cache use size for string
+// returns 0 if capacity would be exceeded
+func(ca *Cache) checkCapacity(v string) uint32 {
+	sz := uint32(len(v))
+	if ca.CacheSize == 0 {
+		return sz
+	}
+	if ca.CacheUseSize + sz > ca.CacheSize {
+		return 0	
+	}
+	return sz
+}
+
+// return 0-indexed frame number where key is defined. -1 if not defined
+func(ca *Cache) frameOf(key string) int {
+	for i, m := range ca.Cache {
+		for k, _ := range m {
+			if k == key {
+				return i
+			}
+		}
+	}
+	return -1
+}

cache/cache_test.go

@@ -0,0 +1,104 @@
+package cache
+
+import (
+	"testing"
+)
+
+func TestNewCache(t *testing.T) {
+	ca := NewCache()
+	if ca.CacheSize != 0 {
+		t.Errorf("cache size not 0")
+	}
+	ca = ca.WithCacheSize(102525)
+	if ca.CacheSize != 102525 {
+		t.Errorf("cache size not 102525")
+	}
+}
+
+func TestStateCacheUse(t *testing.T) {
+	ca := NewCache()
+	ca = ca.WithCacheSize(10)
+	ca.Push()
+	err := ca.Add("bar", "baz", 0)
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Add("inky", "pinky", 0)
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Add("blinky", "clyde", 0)
+	if err == nil {
+		t.Errorf("expected capacity error")
+	}
+}
+
+func TestStateDownUp(t *testing.T) {
+	ca := NewCache()
+	err := ca.Push()
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Add("foo", "bar", 0)
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Add("baz", "xyzzy", 0)
+	if err != nil {
+		t.Error(err)
+	}
+	if ca.CacheUseSize != 8 {
+		t.Errorf("expected cache use size 8 got %v", ca.CacheUseSize)
+	}
+	err = ca.Pop()
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Pop()
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Pop()
+	if err == nil {
+		t.Errorf("expected out of top frame error")
+	}
+}
+
+func TestCacheReset(t *testing.T) {
+	ca := NewCache()
+	err := ca.Add("foo", "bar", 0)
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Add("baz", "xyzzy", 0)
+	if err != nil {
+		t.Error(err)
+	}
+	ca.Reset()
+	if ca.CacheUseSize != 0 {
+		t.Errorf("expected cache use size 0, got %v", ca.CacheUseSize)
+	}
+}
+
+func TestCacheLoadDup(t *testing.T) {
+	ca := NewCache()
+	err := ca.Push()
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Add("foo", "xyzzy", 0)
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Push()
+	err = ca.Add("foo", "baz", 0)
+	if err == nil {
+		t.Errorf("expected fail on duplicate load")
+	}
+	ca.Pop()
+	err = ca.Add("foo", "baz", 0)
+	if err != nil {
+		t.Error(err)
+	}
+}
+

cache/doc.go

@@ -0,0 +1,2 @@
+// Package cache is a memory store for key-value pairs for all loaded symbols available for output.
+package cache

cache/memory.go

@@ -0,0 +1,12 @@
+package cache
+
+// Memory defines the interface for store of a symbol mapped content store.
+type Memory interface {
+	Add(key string, val string, sizeLimit uint16) error
+	Update(key string, val string) error
+	ReservedSize(key string) (uint16, error)
+	Get(key string) (string, error)
+	Push() error
+	Pop() error
+	Reset()
+}

dev/asm/doc.go

@@ -0,0 +1,2 @@
+// Executable asm compiles festival assembly code to bytecode instructions.
+package main

dev/asm/main.go

@@ -6,11 +6,11 @@ import (
 	"log"
 	"os"
 
-	"git.defalsify.org/festive/asm"
+	"git.grassecon.net/kamikazechaser/vise/asm"
 )
 
 func main() {
-	if (len(os.Args) < 2) {
+	if len(os.Args) < 2 {
 		os.Exit(1)
 	}
 	fp := os.Args[1]

dev/disasm/doc.go

@@ -0,0 +1,2 @@
+// Executable disasm generates festival assembly code from bytecode instructions.
+package main

dev/disasm/main.go

@@ -2,14 +2,14 @@ package main
 
 import (
 	"fmt"
-	"os"
 	"io/ioutil"
+	"os"
 
-	"git.defalsify.org/festive/vm"
+	"git.grassecon.net/kamikazechaser/vise/vm"
 )
 
 func main() {
-	if (len(os.Args) < 2) {
+	if len(os.Args) < 2 {
 		os.Exit(1)
 	}
 	fp := os.Args[1]

dev/gendata/doc.go

@@ -0,0 +1,2 @@
+// Execution gendata output testdata provisions compatible with resource.FsResource to a filesystem directory.
+package main

dev/gendata/main.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"os"
 
-	"git.defalsify.org/festive/testdata"
+	"git.grassecon.net/kamikazechaser/vise/testdata"
 )
 
 func main() {

dev/interactive/doc.go

@@ -0,0 +1,2 @@
+// Executable interactive runs the Engine execution loop against interactive client input in the terminal.
+package main

dev/interactive/main.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"os"
+
+	"git.grassecon.net/kamikazechaser/vise/engine"
+)
+
+func main() {
+	var dir string
+	var root string
+	var size uint
+	//var sessionId string
+	flag.StringVar(&dir, "d", ".", "resource dir to read from")
+	flag.UintVar(&size, "s", 0, "max size of output")
+	flag.StringVar(&root, "root", "root", "entry point symbol")
+	//flag.StringVar(&sessionId, "session-id", "default", "session id")
+	flag.Parse()
+	fmt.Fprintf(os.Stderr, "starting session at symbol '%s' using resource dir: %s\n", root, dir)
+
+	ctx := context.Background()
+	en := engine.NewSizedEngine(dir, uint32(size))
+	cont, err := en.Init(ctx)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "engine init exited with error: %v\n", err)
+		os.Exit(1)
+	}
+	if !cont {
+		_, err = en.WriteResult(os.Stdout, ctx)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "dead init write error: %v\n", err)
+			os.Exit(1)
+		}
+		os.Stdout.Write([]byte{0x0a})
+		os.Exit(0)
+	}
+	err = engine.Loop(&en, os.Stdin, os.Stdout, ctx)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "loop exited with error: %v\n", err)
+		os.Exit(1)
+	}
+}

engine/default.go

@@ -0,0 +1,34 @@
+package engine
+
+import (
+	"context"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/resource"
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+// NewDefaultEngine is a convenience function to instantiate a filesystem-backed engine with no output constraints.
+func NewDefaultEngine(dir string) Engine {
+	st := state.NewState(0)
+	rs := resource.NewFsResource(dir)
+	ca := cache.NewCache()
+	cfg := Config{
+		Root: "root",
+	}
+	ctx := context.TODO()
+	return NewEngine(cfg, &st, &rs, ca, ctx)
+}
+
+// NewSizedEngine is a convenience function to instantiate a filesystem-backed engine with a specified output constraint.
+func NewSizedEngine(dir string, size uint32) Engine {
+	st := state.NewState(0)
+	rs := resource.NewFsResource(dir)
+	ca := cache.NewCache()
+	cfg := Config{
+		OutputSize: size,
+		Root:       "root",
+	}
+	ctx := context.TODO()
+	return NewEngine(cfg, &st, &rs, ca, ctx)
+}

engine/doc.go

@@ -0,0 +1,2 @@
+// Package engine orchestrates client input with vm execution.
+package engine

engine/engine.go

@@ -0,0 +1,183 @@
+package engine
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/render"
+	"git.grassecon.net/kamikazechaser/vise/resource"
+	"git.grassecon.net/kamikazechaser/vise/state"
+	"git.grassecon.net/kamikazechaser/vise/vm"
+)
+
+// Config globally defines behavior of all components driven by the engine.
+type Config struct {
+	OutputSize uint32 // Maximum size of output from a single rendered page
+	SessionId  string
+	Root       string
+	FlagCount  uint32
+	CacheSize  uint32
+}
+
+// Engine is an execution engine that handles top-level errors when running client inputs against code in the bytecode buffer.
+type Engine struct {
+	st    *state.State
+	rs    resource.Resource
+	ca    cache.Memory
+	vm    *vm.Vm
+	root  string
+	initd bool
+}
+
+// NewEngine creates a new Engine
+func NewEngine(cfg Config, st *state.State, rs resource.Resource, ca cache.Memory, ctx context.Context) Engine {
+	var szr *render.Sizer
+	if cfg.OutputSize > 0 {
+		szr = render.NewSizer(cfg.OutputSize)
+	}
+	ctx = context.WithValue(ctx, "sessionId", cfg.SessionId)
+	engine := Engine{
+		st: st,
+		rs: rs,
+		ca: ca,
+		vm: vm.NewVm(st, rs, ca, szr),
+	}
+	engine.root = cfg.Root
+
+	return engine
+}
+
+// Init must be explicitly called before using the Engine instance.
+//
+// It loads and executes code for the start node.
+func (en *Engine) Init(ctx context.Context) (bool, error) {
+	if en.initd {
+		log.Printf("already initialized")
+		return true, nil
+	}
+	sym := en.root
+	if sym == "" {
+		return false, fmt.Errorf("start sym empty")
+	}
+	inSave, _ := en.st.GetInput()
+	err := en.st.SetInput([]byte{})
+	if err != nil {
+		return false, err
+	}
+	b := vm.NewLine(nil, vm.MOVE, []string{sym}, nil, nil)
+	log.Printf("start new init VM run with code %x", b)
+	b, err = en.vm.Run(b, ctx)
+	if err != nil {
+		return false, err
+	}
+
+	log.Printf("ended init VM run with code %x", b)
+	en.st.SetCode(b)
+	err = en.st.SetInput(inSave)
+	if err != nil {
+		return false, err
+	}
+	return len(b) > 0, nil
+}
+
+// Exec processes user input against the current state of the virtual machine environment.
+//
+// If successfully executed, output of the last execution is available using the WriteResult call.
+//
+// A bool return valus of false indicates that execution should be terminated. Calling Exec again has undefined effects.
+//
+// Fails if:
+// - input is formally invalid (too long etc)
+// - no current bytecode is available
+// - input processing against bytcode failed
+func (en *Engine) Exec(input []byte, ctx context.Context) (bool, error) {
+	var err error
+	if en.st.Moves == 0 {
+		cont, err := en.Init(ctx)
+		if err != nil {
+			return false, err
+		}
+		return cont, nil
+	}
+	err = vm.ValidInput(input)
+	if err != nil {
+		return true, err
+	}
+	err = en.st.SetInput(input)
+	if err != nil {
+		return false, err
+	}
+
+	log.Printf("new execution with input '%s' (0x%x)", input, input)
+	code, err := en.st.GetCode()
+	if err != nil {
+		return false, err
+	}
+	if len(code) == 0 {
+		return false, fmt.Errorf("no code to execute")
+	}
+
+	log.Printf("start new VM run with code %x", code)
+	code, err = en.vm.Run(code, ctx)
+	if err != nil {
+		return false, err
+	}
+	log.Printf("ended VM run with code %x", code)
+
+	v, err := en.st.MatchFlag(state.FLAG_TERMINATE, false)
+	if err != nil {
+		return false, err
+	}
+	if v {
+		if len(code) > 0 {
+			log.Printf("terminated with code remaining: %x", code)
+		}
+		return false, err
+	}
+
+	en.st.SetCode(code)
+	if len(code) == 0 {
+		log.Printf("runner finished with no remaining code")
+		_, err = en.reset(ctx)
+		return false, err
+	}
+
+	return true, nil
+}
+
+// WriteResult writes the output of the last vm execution to the given writer.
+//
+// Fails if
+// - required data inputs to the template are not available.
+// - the template for the given node point is note available for retrieval using the resource.Resource implementer.
+// - the supplied writer fails to process the writes.
+func (en *Engine) WriteResult(w io.Writer, ctx context.Context) (int, error) {
+	r, err := en.vm.Render(ctx)
+	if err != nil {
+		return 0, err
+	}
+	return io.WriteString(w, r)
+}
+
+// start execution over at top node while keeping current state of client error flags.
+func (en *Engine) reset(ctx context.Context) (bool, error) {
+	var err error
+	var isTop bool
+	for !isTop {
+		isTop, err = en.st.Top()
+		if err != nil {
+			return false, err
+		}
+		_, err = en.st.Up()
+		if err != nil {
+			return false, err
+		}
+		en.ca.Pop()
+	}
+	en.st.Restart()
+	en.initd = false
+	return en.Init(ctx)
+}

engine/engine_test.go

@@ -0,0 +1,187 @@
+package engine
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io/ioutil"
+	"path"
+	"testing"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/resource"
+	"git.grassecon.net/kamikazechaser/vise/state"
+	"git.grassecon.net/kamikazechaser/vise/testdata"
+)
+
+var (
+	dataGenerated bool   = false
+	dataDir       string = testdata.DataDir
+)
+
+type FsWrapper struct {
+	*resource.FsResource
+	st *state.State
+}
+
+func NewFsWrapper(path string, st *state.State) FsWrapper {
+	rs := resource.NewFsResource(path)
+	wr := FsWrapper{
+		&rs,
+		st,
+	}
+	wr.AddLocalFunc("one", wr.one)
+	wr.AddLocalFunc("inky", wr.inky)
+	wr.AddLocalFunc("pinky", wr.pinky)
+	return wr
+}
+
+func (fs FsWrapper) one(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	return resource.Result{
+		Content: "one",
+	}, nil
+}
+
+func (fs FsWrapper) inky(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	return resource.Result{
+		Content: "tinkywinky",
+	}, nil
+}
+
+func (fs FsWrapper) pinky(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	r := fmt.Sprintf("xyzzy: %x", input)
+	return resource.Result{
+		Content: r,
+	}, nil
+}
+
+func (fs FsWrapper) GetCode(sym string) ([]byte, error) {
+	sym += ".bin"
+	fp := path.Join(fs.Path, sym)
+	r, err := ioutil.ReadFile(fp)
+	return r, err
+}
+
+func generateTestData(t *testing.T) {
+	if dataGenerated {
+		return
+	}
+	var err error
+	dataDir, err = testdata.Generate()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestEngineInit(t *testing.T) {
+	var err error
+	generateTestData(t)
+	ctx := context.TODO()
+	st := state.NewState(17)
+	rs := NewFsWrapper(dataDir, &st)
+	ca := cache.NewCache().WithCacheSize(1024)
+
+	en := NewEngine(Config{
+		Root: "root",
+	}, &st, &rs, ca, ctx)
+
+	_, err = en.Init(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w := bytes.NewBuffer(nil)
+	_, err = en.WriteResult(w, ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	b := w.Bytes()
+	expect_str := `hello world
+1:do the foo
+2:go to the bar`
+
+	if !bytes.Equal(b, []byte(expect_str)) {
+		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect_str, b)
+	}
+
+	input := []byte("1")
+	_, err = en.Exec(input, ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	r, _ := st.Where()
+	if r != "foo" {
+		t.Fatalf("expected where-string 'foo', got %s", r)
+	}
+	w = bytes.NewBuffer(nil)
+	_, err = en.WriteResult(w, ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	b = w.Bytes()
+	expect := `this is in foo
+
+it has more lines
+0:to foo
+1:go bar
+2:see long`
+
+	if !bytes.Equal(b, []byte(expect)) {
+		t.Fatalf("expected\n\t%s\ngot:\n\t%s\n", expect, b)
+	}
+}
+
+func TestEngineExecInvalidInput(t *testing.T) {
+	generateTestData(t)
+	ctx := context.TODO()
+	st := state.NewState(17)
+	rs := NewFsWrapper(dataDir, &st)
+	ca := cache.NewCache().WithCacheSize(1024)
+
+	en := NewEngine(Config{
+		Root: "root",
+	}, &st, &rs, ca, ctx)
+	var err error
+	_, err = en.Init(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = en.Exec([]byte("_foo"), ctx)
+	if err == nil {
+		t.Fatalf("expected fail on invalid input")
+	}
+}
+
+func TestEngineResumeTerminated(t *testing.T) {
+	generateTestData(t)
+	ctx := context.TODO()
+	st := state.NewState(17)
+	rs := NewFsWrapper(dataDir, &st)
+	ca := cache.NewCache().WithCacheSize(1024)
+
+	en := NewEngine(Config{
+		Root: "root",
+	}, &st, &rs, ca, ctx)
+	var err error
+	_, err = en.Init(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = en.Exec([]byte("1"), ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = en.Exec([]byte("1"), ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	location, idx := st.Where()
+	if location != "root" {
+		t.Fatalf("expected 'root', got %s", location)
+	}
+	if idx != 0 {
+		t.Fatalf("expected idx '0', got %v", idx)
+	}
+}

engine/loop.go

@@ -0,0 +1,53 @@
+package engine
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"strings"
+)
+
+// Loop starts an engine execution loop with the given symbol as the starting node.
+//
+// The root reads inputs from the provided reader, one line at a time.
+//
+// It will execute until running out of bytecode in the buffer.
+//
+// Any error not handled by the engine will terminate the oop and return an error.
+//
+// Rendered output is written to the provided writer.
+func Loop(en *Engine, reader io.Reader, writer io.Writer, ctx context.Context) error {
+	var err error
+	_, err = en.WriteResult(writer, ctx)
+	if err != nil {
+		return err
+	}
+	writer.Write([]byte{0x0a})
+
+	running := true
+	bufReader := bufio.NewReader(reader)
+	for running {
+		in, err := bufReader.ReadString('\n')
+		if err == io.EOF {
+			log.Printf("EOF found, that's all folks")
+			return nil
+		}
+		if err != nil {
+			return fmt.Errorf("cannot read input: %v\n", err)
+		}
+		in = strings.TrimSpace(in)
+		running, err = en.Exec([]byte(in), ctx)
+		if err != nil {
+			return fmt.Errorf("unexpected termination: %v\n", err)
+		}
+		_, err = en.WriteResult(writer, ctx)
+		if err != nil {
+			return err
+		}
+		writer.Write([]byte{0x0a})
+
+	}
+	return nil
+}

engine/loop_test.go

@@ -0,0 +1,129 @@
+package engine
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"log"
+	"strings"
+	"testing"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/resource"
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+func TestLoopTop(t *testing.T) {
+	generateTestData(t)
+	ctx := context.TODO()
+	st := state.NewState(0)
+	rs := resource.NewFsResource(dataDir)
+	ca := cache.NewCache().WithCacheSize(1024)
+
+	cfg := Config{
+		Root: "root",
+	}
+	en := NewEngine(cfg, &st, &rs, ca, ctx)
+	var err error
+	_, err = en.Init(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	input := []string{
+		"2",
+		"j",
+		"1",
+	}
+	inputStr := strings.Join(input, "\n")
+	inputBuf := bytes.NewBuffer(append([]byte(inputStr), 0x0a))
+	outputBuf := bytes.NewBuffer(nil)
+	log.Printf("running with input: %s", inputBuf.Bytes())
+
+	err = Loop(&en, inputBuf, outputBuf, ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	location, _ := st.Where()
+	if location != "foo" {
+		fmt.Errorf("expected location 'foo', got %s", location)
+	}
+}
+
+func TestLoopBackForth(t *testing.T) {
+	generateTestData(t)
+	ctx := context.TODO()
+	st := state.NewState(0)
+	rs := resource.NewFsResource(dataDir)
+	ca := cache.NewCache().WithCacheSize(1024)
+
+	cfg := Config{
+		Root: "root",
+	}
+	en := NewEngine(cfg, &st, &rs, ca, ctx)
+	var err error
+	_, err = en.Init(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	input := []string{
+		"1",
+		"0",
+		"1",
+		"0",
+	}
+	inputStr := strings.Join(input, "\n")
+	inputBuf := bytes.NewBuffer(append([]byte(inputStr), 0x0a))
+	outputBuf := bytes.NewBuffer(nil)
+	log.Printf("running with input: %s", inputBuf.Bytes())
+
+	err = Loop(&en, inputBuf, outputBuf, ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestLoopBrowse(t *testing.T) {
+	generateTestData(t)
+	ctx := context.TODO()
+	st := state.NewState(0)
+	rs := resource.NewFsResource(dataDir)
+	ca := cache.NewCache().WithCacheSize(1024)
+
+	cfg := Config{
+		OutputSize: 68,
+		Root:       "root",
+	}
+	en := NewEngine(cfg, &st, &rs, ca, ctx)
+	var err error
+	_, err = en.Init(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	input := []string{
+		"1",
+		"2",
+		"00",
+		"11",
+		"00",
+	}
+	inputStr := strings.Join(input, "\n")
+	inputBuf := bytes.NewBuffer(append([]byte(inputStr), 0x0a))
+	outputBuf := bytes.NewBuffer(nil)
+	log.Printf("running with input: %s", inputBuf.Bytes())
+
+	err = Loop(&en, inputBuf, outputBuf, ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	location, idx := st.Where()
+	if location != "long" {
+		fmt.Errorf("expected location 'long', got %s", location)
+	}
+	if idx != 1 {
+		fmt.Errorf("expected idx 1, got %v", idx)
+	}
+}

engine/persist.go

@@ -0,0 +1,50 @@
+package engine
+
+import (
+	"context"
+	"io"
+
+	"git.grassecon.net/kamikazechaser/vise/persist"
+	"git.grassecon.net/kamikazechaser/vise/resource"
+)
+
+// RunPersisted performs a single vm execution from client input using a persisted state.
+//
+// State is first loaded from storage. The vm is initialized with the state and executed. The new state is then saved to storage.
+//
+// The resulting output of the execution will be written to the provided writer.
+//
+// The state is identified by the SessionId member of the Config. Before first execution, the caller must ensure that an
+// initialized state actually is available for the identifier, otherwise the method will fail.
+//
+// It will also fail if execution by the underlying Engine fails.
+func RunPersisted(cfg Config, rs resource.Resource, pr persist.Persister, input []byte, w io.Writer, ctx context.Context) error {
+	err := pr.Load(cfg.SessionId)
+	if err != nil {
+		return err
+	}
+
+	en := NewEngine(cfg, pr.GetState(), rs, pr.GetMemory(), ctx)
+
+	c, err := en.WriteResult(w, ctx)
+	if err != nil {
+		return err
+	}
+	err = pr.Save(cfg.SessionId)
+	if err != nil {
+		return err
+	}
+	if c > 0 {
+		return err
+	}
+
+	_, err = en.Exec(input, ctx)
+	if err != nil {
+		return err
+	}
+	_, err = en.WriteResult(w, ctx)
+	if err != nil {
+		return err
+	}
+	return pr.Save(cfg.SessionId)
+}

engine/persist_test.go

@@ -0,0 +1,73 @@
+package engine
+
+import (
+	"context"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/persist"
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+func TestPersist(t *testing.T) {
+	generateTestData(t)
+	cfg := Config{
+		OutputSize: 83,
+		SessionId:  "xyzzy",
+		Root:       "root",
+	}
+	rs := NewFsWrapper(dataDir, nil)
+
+	persistDir, err := ioutil.TempDir("", "vise_engine_persist")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	st := state.NewState(3)
+	ca := cache.NewCache().WithCacheSize(1024)
+	pr := persist.NewFsPersister(persistDir).WithContent(&st, ca)
+
+	w := os.Stdout
+	ctx := context.TODO()
+
+	st = state.NewState(cfg.FlagCount)
+	ca = cache.NewCache()
+	ca = ca.WithCacheSize(cfg.CacheSize)
+	pr = persist.NewFsPersister(persistDir).WithContent(&st, ca)
+	err = pr.Save(cfg.SessionId)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	pr = persist.NewFsPersister(persistDir)
+	inputs := []string{
+		"", // trigger init, will not exec
+		"1",
+		"2",
+		"00",
+	}
+	for _, v := range inputs {
+		err = RunPersisted(cfg, rs, pr, []byte(v), w, ctx)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	pr = persist.NewFsPersister(persistDir)
+	err = pr.Load(cfg.SessionId)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	stAfter := pr.GetState()
+	location, idx := stAfter.Where()
+	if location != "long" {
+		t.Fatalf("expected 'long', got %s", location)
+	}
+	if idx != 1 {
+		t.Fatalf("expected '1', got %v", idx)
+	}
+
+}

examples/compile.bash

@@ -0,0 +1,13 @@
+for f in $(ls $1/*.vis); do
+	b=$(basename $f)
+	b=${b%.*}
+	go run ./dev/asm $1/$b.vis > $1/$b.bin
+done
+
+for f in $(ls $1/*.txt.orig); do
+	b=$(basename $f)
+	b=${b%.*}
+	#go run ./dev/asm $1/$b.vis > $1/$b.bin
+	echo $b
+	cp -v $f $1/$b
+done

examples/helloworld/que.txt.orig

@@ -0,0 +1 @@
+world

examples/helloworld/root

@@ -0,0 +1 @@
+hello, {{.que}}!

examples/helloworld/root.vis

@@ -0,0 +1,2 @@
+LOAD que 5
+MAP que

examples/profile/entry_email

@@ -0,0 +1,2 @@
+Your email is now: {{.myemail}}
+Enter new email.

examples/profile/entry_email.vis

@@ -0,0 +1,5 @@
+MAP myemail
+MOUT 0 "abort"
+HALT
+INCMP 0 _
+INCMP * entry_email_save 

examples/profile/entry_email_save.vis

@@ -0,0 +1,3 @@
+LOAD do_email_save 1
+RELOAD myemail
+MOVE _

examples/profile/entry_name

@@ -0,0 +1,2 @@
+Name is currently: {{.myname}}
+Enter new name.

examples/profile/entry_name.vis

@@ -0,0 +1,5 @@
+MAP myname
+MOUT 0 "abort"
+HALT
+INCMP 0 _
+INCMP * entry_name_save 

examples/profile/entry_name_save.vis

@@ -0,0 +1,3 @@
+LOAD do_name_save 1
+RELOAD myname
+MOVE _

examples/profile/identified

@@ -0,0 +1,3 @@
+You are identified as:
+Name: {{.myname}}
+Email: {{.myemail}}

examples/profile/identified.vis

@@ -0,0 +1,2 @@
+MAP myname
+MAP myemail

examples/profile/main.go

@@ -0,0 +1,139 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"path"
+
+	testdataloader "github.com/peteole/testdata-loader"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/engine"
+	"git.grassecon.net/kamikazechaser/vise/resource"
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+const (
+	USERFLAG_IDENTIFIED = iota + state.FLAG_USERSTART
+	USERFLAG_HAVENAME
+	USERFLAG_HAVEEMAIL
+)
+
+var (
+	baseDir     = testdataloader.GetBasePath()
+	scriptDir   = path.Join(baseDir, "examples", "profile")
+	emptyResult = resource.Result{}
+)
+
+type profileResource struct {
+	*resource.FsResource
+	st          *state.State
+	haveEntered bool
+}
+
+func newProfileResource(st *state.State, rs *resource.FsResource) *profileResource {
+	return &profileResource{
+		rs,
+		st,
+		false,
+	}
+}
+
+func (pr *profileResource) checkEntry() error {
+	log.Printf("%v %v", USERFLAG_IDENTIFIED, USERFLAG_HAVENAME)
+	if pr.haveEntered {
+		return nil
+	}
+	one, err := pr.st.GetFlag(USERFLAG_HAVENAME)
+	if err != nil {
+		return err
+	}
+	two, err := pr.st.GetFlag(USERFLAG_HAVEEMAIL)
+	if err != nil {
+		return err
+	}
+	if one && two {
+		_, err = pr.st.SetFlag(USERFLAG_IDENTIFIED)
+		if err != nil {
+			return err
+		}
+		pr.haveEntered = true
+	}
+	return nil
+}
+
+func (pr profileResource) nameSave(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	log.Printf("writing name to file")
+	fp := path.Join(scriptDir, "myname.txt")
+	err := ioutil.WriteFile(fp, input, 0600)
+	if err != nil {
+		return emptyResult, err
+	}
+	changed, err := pr.st.SetFlag(USERFLAG_HAVENAME)
+	if err != nil {
+		return emptyResult, err
+	}
+	if changed {
+		pr.checkEntry()
+	}
+	return emptyResult, err
+}
+
+func (pr profileResource) emailSave(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	log.Printf("writing email to file")
+	fp := path.Join(scriptDir, "myemail.txt")
+	err := ioutil.WriteFile(fp, input, 0600)
+	if err != nil {
+		return emptyResult, err
+	}
+	changed, err := pr.st.SetFlag(USERFLAG_HAVEEMAIL)
+	if err != nil {
+		return emptyResult, err
+	}
+	if changed {
+		pr.checkEntry()
+	}
+	return resource.Result{}, err
+}
+
+func main() {
+	var dir string
+	var root string
+	var size uint
+	var sessionId string
+	flag.UintVar(&size, "s", 0, "max size of output")
+	flag.StringVar(&root, "root", "root", "entry point symbol")
+	flag.StringVar(&sessionId, "session-id", "default", "session id")
+	flag.Parse()
+	fmt.Fprintf(os.Stderr, "starting session at symbol '%s' using resource dir: %s\n", root, dir)
+
+	st := state.NewState(3)
+	rsf := resource.NewFsResource(scriptDir)
+	rs := newProfileResource(&st, &rsf)
+	rs.AddLocalFunc("do_name_save", rs.nameSave)
+	rs.AddLocalFunc("do_email_save", rs.emailSave)
+	ca := cache.NewCache()
+	cfg := engine.Config{
+		Root:       "root",
+		SessionId:  sessionId,
+		OutputSize: uint32(size),
+	}
+	ctx := context.Background()
+	en := engine.NewEngine(cfg, &st, rs, ca, ctx)
+	var err error
+	_, err = en.Init(ctx)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "engine init fail: %v\n", err)
+		os.Exit(1)
+	}
+
+	err = engine.Loop(&en, os.Stdin, os.Stdout, ctx)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "loop exited with error: %v\n", err)
+		os.Exit(1)
+	}
+}

examples/profile/myemail.txt.orig

@@ -0,0 +1 @@
+(not set)

examples/profile/myname.txt.orig

@@ -0,0 +1 @@
+(not set)

examples/profile/root

@@ -0,0 +1 @@
+Please input profile data

examples/profile/root.vis

@@ -0,0 +1,5 @@
+LOAD myname 64
+LOAD myemail 64
+CATCH identified 8 0
+DOWN entry_name 0 "name"
+DOWN entry_email 1 "email"

examples/session/input

@@ -0,0 +1,2 @@
+hey hey hey
+your data is {{.do_save}}

examples/session/input.vis

@@ -0,0 +1,4 @@
+MAP do_save
+HALT
+RELOAD do_save
+INCMP * .

examples/session/main.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"path"
+
+	testdataloader "github.com/peteole/testdata-loader"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/engine"
+	"git.grassecon.net/kamikazechaser/vise/resource"
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+var (
+	baseDir     = testdataloader.GetBasePath()
+	scriptDir   = path.Join(baseDir, "examples", "session")
+	emptyResult = resource.Result{}
+)
+
+func save(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	sessionId := ctx.Value("SessionId").(string)
+	sessionDir := path.Join(scriptDir, sessionId)
+	err := os.MkdirAll(sessionDir, 0700)
+	if err != nil {
+		return emptyResult, err
+	}
+	fp := path.Join(sessionDir, "data.txt")
+	if len(input) > 0 {
+		log.Printf("write data %s session %s", input, sessionId)
+		err = ioutil.WriteFile(fp, input, 0600)
+		if err != nil {
+			return emptyResult, err
+		}
+	}
+	r, err := ioutil.ReadFile(fp)
+	if err != nil {
+		err = ioutil.WriteFile(fp, []byte("(not set)"), 0600)
+		if err != nil {
+			return emptyResult, err
+		}
+	}
+	return resource.Result{
+		Content: string(r),
+	}, nil
+}
+
+func main() {
+	var root string
+	var size uint
+	var sessionId string
+	flag.UintVar(&size, "s", 0, "max size of output")
+	flag.StringVar(&root, "root", "root", "entry point symbol")
+	flag.StringVar(&sessionId, "session-id", "default", "session id")
+	flag.Parse()
+	fmt.Fprintf(os.Stderr, "starting session at symbol '%s' using resource dir: %s\n", root, scriptDir)
+
+	st := state.NewState(0)
+	rs := resource.NewFsResource(scriptDir)
+	rs.AddLocalFunc("do_save", save)
+	ca := cache.NewCache()
+	cfg := engine.Config{
+		Root:       "root",
+		SessionId:  sessionId,
+		OutputSize: uint32(size),
+	}
+	ctx := context.Background()
+	ctx = context.WithValue(ctx, "SessionId", sessionId)
+	en := engine.NewEngine(cfg, &st, rs, ca, ctx)
+	var err error
+	_, err = en.Init(ctx)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "engine init fail: %v\n", err)
+		os.Exit(1)
+	}
+	err = engine.Loop(&en, os.Stdin, os.Stdout, ctx)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "loop exited with error: %v\n", err)
+		os.Exit(1)
+	}
+}

examples/session/root.vis

@@ -0,0 +1,2 @@
+LOAD do_save 0
+MOVE input

examples/validate/end

@@ -0,0 +1,2 @@
+You made it.
+Any input to go again.

examples/validate/end.vis

@@ -0,0 +1,3 @@
+HALT
+LOAD again 0
+INCMP * _

examples/validate/main.go

@@ -0,0 +1,84 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"os"
+	"path"
+
+	testdataloader "github.com/peteole/testdata-loader"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/engine"
+	"git.grassecon.net/kamikazechaser/vise/resource"
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+var (
+	baseDir     = testdataloader.GetBasePath()
+	scriptDir   = path.Join(baseDir, "examples", "validate")
+	emptyResult = resource.Result{}
+)
+
+const (
+	USERFLAG_HAVESOMETHING = state.FLAG_USERSTART
+)
+
+type verifyResource struct {
+	*resource.FsResource
+	st *state.State
+}
+
+func (vr *verifyResource) verify(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	var err error
+	if string(input) == "something" {
+		_, err = vr.st.SetFlag(USERFLAG_HAVESOMETHING)
+	}
+	return resource.Result{
+		Content: "",
+	}, err
+}
+
+func (vr *verifyResource) again(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	var err error
+	_, err = vr.st.ResetFlag(USERFLAG_HAVESOMETHING)
+	return resource.Result{}, err
+}
+
+func main() {
+	var root string
+	var size uint
+	var sessionId string
+	flag.UintVar(&size, "s", 0, "max size of output")
+	flag.StringVar(&root, "root", "root", "entry point symbol")
+	flag.StringVar(&sessionId, "session-id", "default", "session id")
+	flag.Parse()
+	fmt.Fprintf(os.Stderr, "starting session at symbol '%s' using resource dir: %s\n", root, scriptDir)
+
+	st := state.NewState(1)
+	rsf := resource.NewFsResource(scriptDir)
+	rs := verifyResource{&rsf, &st}
+	rs.AddLocalFunc("verifyinput", rs.verify)
+	rs.AddLocalFunc("again", rs.again)
+	ca := cache.NewCache()
+	cfg := engine.Config{
+		Root:       "root",
+		SessionId:  sessionId,
+		OutputSize: uint32(size),
+	}
+	ctx := context.Background()
+	ctx = context.WithValue(ctx, "SessionId", sessionId)
+	en := engine.NewEngine(cfg, &st, rs, ca, ctx)
+	var err error
+	_, err = en.Init(ctx)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "engine init fail: %v\n", err)
+		os.Exit(1)
+	}
+	err = engine.Loop(&en, os.Stdin, os.Stdout, ctx)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "loop exited with error: %v\n", err)
+		os.Exit(1)
+	}
+}

examples/validate/root

@@ -0,0 +1 @@
+Please write "something"

examples/validate/root.vis

@@ -0,0 +1,6 @@
+LOAD verifyinput 0
+MAP verifyinput
+HALT
+RELOAD verifyinput
+CATCH . 8 1
+MOVE end

go.mod

@@ -0,0 +1,11 @@
+module git.grassecon.net/kamikazechaser/vise
+
+go 1.20
+
+require (
+	github.com/alecthomas/participle/v2 v2.0.0
+	github.com/fxamacker/cbor/v2 v2.4.0
+	github.com/peteole/testdata-loader v0.3.0
+)
+
+require github.com/x448/float16 v0.8.4 // indirect

go/asm/menu.go

@@ -1,86 +0,0 @@
-package asm
-
-import (
-	"fmt"
-
-	"git.defalsify.org/festive/vm"
-)
-
-type BatchCode uint16
-
-const (
-	_MENU_OFFSET = 256
-	MENU_DOWN = _MENU_OFFSET
-	MENU_UP = _MENU_OFFSET + 1
-	MENU_NEXT = _MENU_OFFSET + 2
-	MENU_PREVIOUS = _MENU_OFFSET + 3
-	//MENU_BROWSE = _MENU_OFFSET + 4
-)
-
-var (
-	batchCode = map[string]BatchCode{
-		"DOWN": MENU_DOWN,
-		"UP": MENU_UP,
-		"NEXT": MENU_NEXT,
-		"PREVIOUS": MENU_PREVIOUS,
-		//"BROWSE": MENU_BROWSE, 
-	}
-)
-
-type menuItem struct {
-	code BatchCode
-	choice string
-	display string
-	target string
-}
-
-type MenuProcessor struct {
-	items []menuItem
-	size uint32
-}
-
-func NewMenuProcessor() MenuProcessor {
-	return MenuProcessor{}
-}
-
-func(mp *MenuProcessor) Add(bop string, choice string, display string, target string) error {
-	bopCode := batchCode[bop]
-	if bopCode == 0 {
-		return fmt.Errorf("unknown menu instruction: %v", bop)
-	}
-	if len(target) > 0 && bopCode != MENU_DOWN {
-		return fmt.Errorf("target is only valid for DOWN")
-	}
-	m := menuItem{
-		code: bopCode,
-		choice: choice,
-		display: display,
-		target: target,
-	}
-	mp.items = append(mp.items, m)
-	return nil
-}
-
-func (mp *MenuProcessor) ToLines() []byte {
-	preLines := []byte{}
-	postLines := []byte{}
-
-	for _, v := range mp.items {
-		preLines = vm.NewLine(preLines, vm.MOUT, []string{v.choice, v.display}, nil, nil)
-		switch v.code {
-		case MENU_UP:
-			postLines = vm.NewLine(postLines, vm.INCMP, []string{v.choice, "_"}, nil, nil)
-		case MENU_NEXT:
-			_ = postLines
-		case MENU_PREVIOUS:
-			_ = postLines
-		default:
-			postLines = vm.NewLine(postLines, vm.INCMP, []string{v.choice, v.target}, nil, nil)
-		}
-	}
-
-	preLines = vm.NewLine(preLines, vm.HALT, nil, nil, nil)
-	return append(preLines, postLines...)
-}
-
-

go/dev/interactive.go

@@ -1,49 +0,0 @@
-package main
-
-import (
-	"bufio"
-	"bytes"
-	"context"
-	"flag"
-	"fmt"
-	"strings"
-	"os"
-
-	"git.defalsify.org/festive/engine"
-)
-
-func main() {
-	var dir string
-	var root string
-	flag.StringVar(&dir, "d", ".", "resource dir to read from")
-	flag.StringVar(&root, "root", "root", "entry point symbol")
-	flag.Parse()
-	fmt.Fprintf(os.Stderr, "starting session at symbol '%s' using resource dir: %s\n", root, dir)
-
-	ctx := context.Background()
-	en := engine.NewDefaultEngine(dir)
-	err := en.Init(root, ctx)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "cannot init: %v\n", err)
-		os.Exit(1)
-	}
-
-	running := true
-	for running {
-		reader := bufio.NewReader(os.Stdin)
-		in, err := reader.ReadString('\n')
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "cannot read input: %v\n", err)
-			os.Exit(1)
-		}
-		in = strings.TrimSpace(in)
-		err = en.Exec([]byte(in), ctx)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "execution terminated: %v\n", err)
-			os.Exit(1)
-		}
-		b := bytes.NewBuffer(nil)
-		en.WriteResult(b)
-		fmt.Println(b.String())
-	}
-}

go/engine/default.go

@@ -1,12 +0,0 @@
-package engine
-
-import (
-	"git.defalsify.org/festive/state"
-	"git.defalsify.org/festive/resource"
-)
-
-func NewDefaultEngine(dir string) Engine {
-	st := state.NewState(0)
-	rs := resource.NewFsResource(dir)
-	return NewEngine(&st, &rs)
-}

go/engine/engine.go

@@ -1,103 +0,0 @@
-package engine
-
-import (
-	"context"
-	"fmt"
-	"io"
-	"log"
-
-	"git.defalsify.org/festive/resource"
-	"git.defalsify.org/festive/state"
-	"git.defalsify.org/festive/vm"
-)
-//
-//type Config struct {
-//	FlagCount uint32
-//	CacheSize uint32
-//}
-
-// Engine is an execution engine that handles top-level errors when running user inputs against currently exposed bytecode.
-type Engine struct {
-	st *state.State
-	rs resource.Resource
-}
-
-// NewEngine creates a new Engine
-func NewEngine(st *state.State, rs resource.Resource) Engine {
-	engine := Engine{st, rs}
-	return engine
-}
-
-// Init must be explicitly called before using the Engine instance.
-//
-// It makes sure bootstrapping code has been executed, and that the exposed bytecode is ready for user input.
-func(en *Engine) Init(sym string, ctx context.Context) error {
-	b := vm.NewLine(nil, vm.MOVE, []string{sym}, nil, nil)
-	var err error
-	b, err = vm.Run(b, en.st, en.rs, ctx)
-	if err != nil {
-		return err
-	}
-	en.st.SetCode(b)
-	return nil
-}
-
-// Exec processes user input against the current state of the virtual machine environment.
-//
-// If successfully executed:
-// - output of the last execution is available using the WriteResult(...) call
-// - Exec(...) may be called again with new input
-//
-// This implementation is in alpha state. That means that any error emitted may have left the system in an undefined state.
-//
-// TODO: Disambiguate errors as critical and resumable errors.
-//
-// Fails if:
-// - input is objectively invalid (too long etc)
-// - no current bytecode is available
-// - input processing against bytcode failed
-func (en *Engine) Exec(input []byte, ctx context.Context) error {
-	err := en.st.SetInput(input)
-	if err != nil {
-		return err
-	}
-	log.Printf("new execution with input 0x%x (%v)", input, len(input))
-	code, err := en.st.GetCode()
-	if err != nil {
-		return err
-	}
-	if len(code) == 0 {
-		return fmt.Errorf("no code to execute")
-	}
-	code, err = vm.Run(code, en.st, en.rs, ctx)
-	en.st.SetCode(code)
-	return err
-}
-
-// WriteResult writes the output of the last vm execution to the given writer.
-//
-// Fails if
-// - required data inputs to the template are not available.
-// - the template for the given node point is note available for retrieval using the resource.Resource implementer.
-// - the supplied writer fails to process the writes.
-func(en *Engine) WriteResult(w io.Writer) error {
-	location := en.st.Where()
-	v, err := en.st.Get()
-	if err != nil {
-		return err
-	}
-	r, err := en.rs.RenderTemplate(location, v)
-	if err != nil {
-		return err
-	}
-	m, err := en.rs.RenderMenu()
-	if err != nil {
-		return err
-	}
-	if len(m) > 0 {
-		r += "\n" + m
-	}
-	c, err := io.WriteString(w, r)
-	log.Printf("%v bytes written as result for %v", c, location)
-	return err
-}

go/engine/engine_test.go

@@ -1,118 +0,0 @@
-package engine
-
-import (
-	"bytes"
-	"context"
-	"fmt"
-	"io/ioutil"
-	"path"
-	"testing"
-
-	"git.defalsify.org/festive/resource"
-	"git.defalsify.org/festive/state"
-	"git.defalsify.org/festive/testdata"
-)
-
-var (
-	dataGenerated bool = false
-	dataDir string = testdata.DataDir
-)
-
-type FsWrapper struct {
-	*resource.FsResource
-	st *state.State
-}
-
-func NewFsWrapper(path string, st *state.State) FsWrapper {
-	rs := resource.NewFsResource(path)
-	return FsWrapper {
-		&rs, 
-		st,
-	}
-}
-
-func (r FsWrapper) RenderTemplate(sym string, values map[string]string) (string, error) {
-	return resource.DefaultRenderTemplate(r, sym, values)	
-}
-
-func(fs FsWrapper) one(ctx context.Context) (string, error) {
-	return "one", nil
-}
-
-func(fs FsWrapper) inky(ctx context.Context) (string, error) {
-	return "tinkywinky", nil
-}
-
-func(fs FsWrapper) FuncFor(sym string) (resource.EntryFunc, error) {
-	switch sym {
-	case "one":
-		return fs.one, nil
-	case "inky":
-		return fs.inky, nil
-	}
-	return nil, fmt.Errorf("function for %v not found", sym)
-}
-
-func(fs FsWrapper) GetCode(sym string) ([]byte, error) {
-	sym += ".bin"
-	fp := path.Join(fs.Path, sym)
-	r, err := ioutil.ReadFile(fp)
-	return r, err
-}
-
-func generateTestData(t *testing.T) {
-	if dataGenerated {
-		return
-	}
-	var err error
-	dataDir, err = testdata.Generate()
-	if err != nil {
-		t.Fatal(err)
-	}
-}
-
-func TestEngineInit(t *testing.T) {
-	st := state.NewState(17).WithCacheSize(1024)
-	generateTestData(t)
-	ctx := context.TODO()
-	rs := NewFsWrapper(dataDir, &st)
-	en := NewEngine(&st, &rs)
-	err := en.Init("root", ctx)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	w := bytes.NewBuffer(nil)
-	err = en.WriteResult(w)
-	if err != nil {
-		t.Fatal(err)
-	}
-	b := w.Bytes()
-	if !bytes.Equal(b, []byte("hello world")) {
-		t.Fatalf("expected result 'hello world', got %v", b)
-	}
-
-	input := []byte("1")
-	err = en.Exec(input, ctx)
-	if err != nil {
-		t.Fatal(err)
-	}
-	r := st.Where()
-	if r != "foo" {
-		t.Fatalf("expected where-string 'foo', got %s", r)
-	}
-	w = bytes.NewBuffer(nil)
-	err = en.WriteResult(w)
-	if err != nil {
-		t.Fatal(err)
-	}
-	b = w.Bytes()
-	expect := `this is in foo
-
-it has more lines
-0:to foo
-1:go bar`
-	if !bytes.Equal(b, []byte(expect)) {
-		t.Fatalf("expected\n\t%s\ngot:\n\t%s\n", expect, b)
-	}
-}

go/go.mod

@@ -1,8 +0,0 @@
-module git.defalsify.org/festive
-
-go 1.20
-
-require (
-	github.com/alecthomas/participle/v2 v2.0.0
-	github.com/peteole/testdata-loader v0.3.0
-)

go/resource/fs.go

@@ -1,49 +0,0 @@
-package resource
-
-import (
-	"fmt"
-	"io/ioutil"
-	"path"
-	"path/filepath"
-	"strings"
-)
-
-type FsResource struct {
-	MenuResource
-	Path string
-}
-
-func NewFsResource(path string) (FsResource) {
-	absPath, err := filepath.Abs(path)
-	if err != nil {
-		panic(err)
-	}
-	return FsResource{
-		Path: absPath,
-	}
-}
-
-func(fs FsResource) GetTemplate(sym string) (string, error) {
-	fp := path.Join(fs.Path, sym)
-	r, err := ioutil.ReadFile(fp)
-	s := string(r)
-	return strings.TrimSpace(s), err
-}
-
-func(fs FsResource) RenderTemplate(sym string, values map[string]string) (string, error) {
-	return DefaultRenderTemplate(&fs, sym, values)
-}
-
-func(fs FsResource) GetCode(sym string) ([]byte, error) {
-	fb := sym + ".bin"
-	fp := path.Join(fs.Path, fb)
-	return ioutil.ReadFile(fp)
-}
-
-func(fs FsResource) FuncFor(sym string) (EntryFunc, error) {
-	return nil, fmt.Errorf("not implemented")
-}
-
-func(rs FsResource) String() string {
-	return fmt.Sprintf("fs resource at path: %s", rs.Path)
-}

go/resource/render.go

@@ -1,25 +0,0 @@
-package resource
-
-import (
-	"bytes"
-	"text/template"
-)
-
-func DefaultRenderTemplate(r Resource, sym string, values map[string]string) (string, error) {
-	v, err := r.GetTemplate(sym)
-	if err != nil {
-		return "", err
-	}
-	tp, err := template.New("tester").Option("missingkey=error").Parse(v)
-	if err != nil {
-		return "", err
-	}
-
-	b := bytes.NewBuffer([]byte{})
-	err = tp.Execute(b, values)
-	if err != nil {
-		return "", err
-	}
-	return b.String(), err
-}
-

go/resource/resource.go

@@ -1,69 +0,0 @@
-package resource
-
-import (
-	"context"
-	"fmt"
-	"log"
-)
-
-// EntryFunc is a function signature for retrieving value for a key
-type EntryFunc func(ctx context.Context) (string, error)
-
-// Resource implementation are responsible for retrieving values and templates for symbols, and can render templates from value dictionaries.
-type Resource interface {
-	GetTemplate(sym string) (string, error) // Get the template for a given symbol.
-	GetCode(sym string) ([]byte, error) // Get the bytecode for the given symbol.
-	PutMenu(string, string) error // Add a menu item.
-	ShiftMenu() (string, string, error) // Remove and return the first menu item in list.
-	SetMenuBrowse(string, string, bool) error // Set menu browser display details.
-	RenderTemplate(sym string, values map[string]string) (string, error) // Render the given data map using the template of the symbol.
-	RenderMenu() (string, error)
-	FuncFor(sym string) (EntryFunc, error) // Resolve symbol code point for.
-}
-
-type MenuResource struct {
-	menu [][2]string
-	next [2]string
-	prev [2]string
-}
-
-func(m *MenuResource) SetMenuBrowse(selector string, title string, back bool) error {
-	entry := [2]string{selector, title}
-	if back {
-		m.prev = entry
-	} else {
-		m.next = entry
-	}
-	return nil
-}
-
-func(m *MenuResource) PutMenu(selector string, title string) error {
-	m.menu = append(m.menu, [2]string{selector, title})
-	log.Printf("menu %v", m.menu)
-	return nil
-}
-
-func(m *MenuResource) ShiftMenu() (string, string, error) {
-	if len(m.menu) == 0 {
-		return "", "", fmt.Errorf("menu is empty")
-	}
-	r := m.menu[0]
-	m.menu = m.menu[1:]
-	return r[0], r[1], nil
-}
-
-func(m *MenuResource) RenderMenu() (string, error) {
-	r := ""
-	for true {
-		l := len(r)
-		choice, title, err := m.ShiftMenu()
-		if err != nil {
-			break
-		}
-		if l > 0 {
-			r += "\n"
-		}
-		r += fmt.Sprintf("%s:%s", choice, title)
-	}
-	return r, nil
-}

go/state/flag.go

@@ -1,5 +0,0 @@
-package state
-
-const (
-	FLAG_INMATCH = 1
-)

go/state/state.go

@@ -1,434 +0,0 @@
-package state
-
-import (
-	"fmt"
-	"log"
-)
-
-// State holds the command stack, error condition of a unique execution session.
-//
-// It also holds cached values for all results of executed symbols.
-//
-// Cached values are linked to the command stack level it which they were loaded. When they go out of scope they are freed.
-//
-// Values must be mapped to a level in order to be available for retrieval and count towards size
-//
-// It can hold a single argument, which is freed once it is read
-//
-// Symbols are loaded with individual size limitations. The limitations apply if a load symbol is updated. Symbols may be added with a 0-value for limits, called a "sink." If mapped, the sink will consume all net remaining size allowance unused by other symbols. Only one sink may be mapped per level.
-//
-// Symbol keys do not count towards cache size limitations.
-//
-// 8 first flags are reserved.
-//
-// TODO factor out cache
-type State struct {
-	Flags []byte // Error state
-	CacheSize uint32 // Total allowed cumulative size of values (not code) in cache
-	CacheUseSize uint32 // Currently used bytes by all values (not code) in cache
-	Cache []map[string]string // All loaded cache items
-	CacheMap map[string]string // Mapped
-	input []byte // Last input
-	code []byte // Pending bytecode to execute
-	execPath []string // Command symbols stack
-	arg *string // Optional argument. Nil if not set.
-	sizes map[string]uint16 // Size limits for all loaded symbols.
-	sink *string // Sink symbol set for level
-	bitSize uint32 // size of (32-bit capacity) bit flag byte array
-	//sizeIdx uint16
-}
-
-func toByteSize(bitSize uint32) uint8 {
-	if bitSize == 0 {
-		return 0
-	}
-	n := bitSize % 8
-	if n > 0 {
-		bitSize += (8 - n)
-	}
-	return uint8(bitSize / 8)
-}
-
-// Retrieve the state of a state flag
-func getFlag(bitIndex uint32, bitField []byte) bool {
-	byteIndex := bitIndex / 8
-	localBitIndex := bitIndex % 8
-	b := bitField[byteIndex]
-	return (b & (1 << localBitIndex)) > 0
-}
-
-// NewState creates a new State object with bitSize number of error condition states in ADDITION to the 8 builtin flags.
-func NewState(bitSize uint32) State {
-	st := State{
-		CacheSize: 0,
-		CacheUseSize: 0,
-		bitSize: bitSize + 8,
-	}
-	byteSize := toByteSize(bitSize + 8)
-	if byteSize > 0 {
-		st.Flags = make([]byte, byteSize) 
-	} else {
-		st.Flags = []byte{}
-	}
-	st.Down("")
-	return st
-}
-
-// SetFlag sets the flag at the given bit field index
-//
-// Returns true if bit state was changed.
-//
-// Fails if bitindex is out of range.
-func(st *State) SetFlag(bitIndex uint32) (bool, error) {
-	if bitIndex + 1 > st.bitSize {
-		return false, fmt.Errorf("bit index %v is out of range of bitfield size %v", bitIndex, st.bitSize)
-	}
-	r := getFlag(bitIndex, st.Flags)
-	if r {
-		return false, nil
-	}
-	byteIndex := bitIndex / 8
-	localBitIndex := bitIndex % 8
-	b := st.Flags[byteIndex] 
-	st.Flags[byteIndex] = b | (1 << localBitIndex)
-	return true, nil
-}
-
-
-// ResetFlag resets the flag at the given bit field index.
-//
-// Returns true if bit state was changed.
-//
-// Fails if bitindex is out of range.
-func(st *State) ResetFlag(bitIndex uint32) (bool, error) {
-	if bitIndex + 1 > st.bitSize {
-		return false, fmt.Errorf("bit index %v is out of range of bitfield size %v", bitIndex, st.bitSize)
-	}
-	r := getFlag(bitIndex, st.Flags)
-	if !r {
-		return false, nil
-	}
-	byteIndex := bitIndex / 8
-	localBitIndex := bitIndex % 8
-	b := st.Flags[byteIndex] 
-	st.Flags[byteIndex] = b & (^(1 << localBitIndex))
-	return true, nil
-}
-
-// GetFlag returns the state of the flag at the given bit field index.
-//
-// Fails if bit field index is out of range.
-func(st *State) GetFlag(bitIndex uint32) (bool, error) {
-	if bitIndex + 1 > st.bitSize {
-		return false, fmt.Errorf("bit index %v is out of range of bitfield size %v", bitIndex, st.bitSize)
-	}
-	return getFlag(bitIndex, st.Flags), nil
-}
-
-// FlagBitSize reports the amount of bits available in the bit field index.
-func(st *State) FlagBitSize() uint32 {
-	return st.bitSize
-}
-
-// FlagBitSize reports the amount of bits available in the bit field index.
-func(st *State) FlagByteSize() uint8 {
-	return uint8(len(st.Flags))
-}
-
-// GetIndex scans a byte slice in same order as in storage, and returns the index of the first set bit.
-//
-// If the given byte slice is too small for the bit field bitsize, the check will terminate at end-of-data without error.
-func(st *State) GetIndex(flags []byte) bool {
-	var globalIndex uint32
-	if st.bitSize == 0 {
-		return false
-	}
-	if len(flags) == 0 {
-		return false
-	}
-	var byteIndex uint8
-	var localIndex uint8
-	l := uint8(len(flags))
-	var i uint32
-	for i = 0; i < st.bitSize; i++ {
-		testVal := flags[byteIndex] & (1 << localIndex)
-		if (testVal & st.Flags[byteIndex]) > 0 {
-			return true
-		}
-		globalIndex += 1
-		if globalIndex % 8 == 0 {
-			byteIndex += 1
-			localIndex = 0
-			if byteIndex > (l - 1) {
-				return false				
-			}
-		} else {
-			localIndex += 1
-		}
-	}
-	return false
-}
-
-// WithCacheSize applies a cumulative cache size limitation for all cached items.
-func(st State) WithCacheSize(cacheSize uint32) State {
-	st.CacheSize = cacheSize
-	return st
-}
-
-// Where returns the current active rendering symbol.
-func(st State) Where() string {
-	if len(st.execPath) == 0 {
-		return ""
-	}
-	l := len(st.execPath)
-	return st.execPath[l-1]
-}
-
-// Down adds the given symbol to the command stack.
-//
-// Clears mapping and sink.
-func(st *State) Down(input string) {
-	m := make(map[string]string)
-	st.Cache = append(st.Cache, m)
-	st.sizes = make(map[string]uint16)
-	st.execPath = append(st.execPath, input)
-	st.resetCurrent()
-}
-
-
-// Up removes the latest symbol to the command stack, and make the previous symbol current.
-//
-// Frees all symbols and associated values loaded at the previous stack level. Cache capacity is increased by the corresponding amount.
-//
-// Clears mapping and sink.
-//
-// Fails if called at top frame.
-func(st *State) Up() error {
-	l := len(st.Cache)
-	if l == 0 {
-		return fmt.Errorf("exit called beyond top frame")
-	}
-	l -= 1
-	m := st.Cache[l]
-	for k, v := range m {
-		sz := len(v)
-		st.CacheUseSize -= uint32(sz)
-		log.Printf("free frame %v key %v value size %v", l, k, sz)
-	}
-	st.Cache = st.Cache[:l]
-	st.execPath = st.execPath[:l]
-	st.resetCurrent()
-	return nil
-}
-
-// Add adds a cache value under a cache symbol key.
-//
-// Also stores the size limitation of for key for later updates.
-//
-// Fails if:
-// - key already defined
-// - value is longer than size limit
-// - adding value exceeds cumulative cache capacity
-func(st *State) Add(key string, value string, sizeLimit uint16) error {
-	if sizeLimit > 0 {
-		l := uint16(len(value))
-		if l > sizeLimit {
-			return fmt.Errorf("value length %v exceeds value size limit %v", l, sizeLimit)
-		}
-	}
-	checkFrame := st.frameOf(key)
-	if checkFrame > -1 {
-		if checkFrame == len(st.execPath) - 1 {
-			log.Printf("Ignoring load request on frame that has symbol already loaded")
-			return nil
-		}
-		return fmt.Errorf("key %v already defined in frame %v", key, checkFrame)
-	}
-	sz := st.checkCapacity(value)
-	if sz == 0 {
-		return fmt.Errorf("Cache capacity exceeded %v of %v", st.CacheUseSize + sz, st.CacheSize)
-	}
-	log.Printf("add key %s value size %v", key, sz)
-	st.Cache[len(st.Cache)-1][key] = value
-	st.CacheUseSize += sz
-	st.sizes[key] = sizeLimit
-	return nil
-}
-
-// Update sets a new value for an existing key.
-//
-// Uses the size limitation from when the key was added.
-//
-// Fails if:
-// - key not defined
-// - value is longer than size limit
-// - replacing value exceeds cumulative cache capacity
-func(st *State) Update(key string, value string) error {
-	sizeLimit := st.sizes[key]
-	if st.sizes[key] > 0 {
-		l := uint16(len(value))
-		if l > sizeLimit {
-			return fmt.Errorf("update value length %v exceeds value size limit %v", l, sizeLimit)
-		}
-	}
-	checkFrame := st.frameOf(key)
-	if checkFrame == -1 {
-		return fmt.Errorf("key %v not defined", key)
-	}
-	r := st.Cache[checkFrame][key]
-	l := uint32(len(r))
-	st.Cache[checkFrame][key] = ""
-	if st.CacheMap[key] != "" {
-		st.CacheMap[key] = value
-	}
-	st.CacheUseSize -= l
-	sz := st.checkCapacity(value)
-	if sz == 0 {
-		baseUseSize := st.CacheUseSize
-		st.Cache[checkFrame][key] = r
-		st.CacheUseSize += l
-		return fmt.Errorf("Cache capacity exceeded %v of %v", baseUseSize + sz, st.CacheSize)
-	}
-	return nil
-}
-
-// Map marks the given key for retrieval.
-//
-// After this, Val() will return the value for the key, and Size() will include the value size and limitations in its calculations.
-//
-// Only one symbol with no size limitation may be mapped at the current level.
-func(st *State) Map(key string) error {
-	m, err := st.Get()
-	if err != nil {
-		return err
-	}
-	l := st.sizes[key]
-	if l == 0 {
-		if st.sink != nil {
-			return fmt.Errorf("sink already set to symbol '%v'", *st.sink)
-		}
-		st.sink = &key
-	}
-	st.CacheMap[key] = m[key]
-	return nil
-}
-
-// Depth returns the current call stack depth.
-func(st *State) Depth() uint8 {
-	return uint8(len(st.Cache))
-}
-
-// Get returns the full key-value mapping for all mapped keys at the current cache level.
-func(st *State) Get() (map[string]string, error) {
-	if len(st.Cache) == 0 {
-		return nil, fmt.Errorf("get at top frame")
-	}
-	return st.Cache[len(st.Cache)-1], nil
-}
-
-// Val returns value for key
-//
-// Fails if key is not mapped.
-func(st *State) Val(key string) (string, error) {
-	r := st.CacheMap[key]
-	if len(r) == 0 {
-		return "", fmt.Errorf("key %v not mapped", key)
-	}
-	return r, nil
-}
-
-// Reset flushes all state contents below the top level, and returns to the top level.
-func(st *State) Reset() {
-	if len(st.Cache) == 0 {
-		return
-	}
-	st.Cache = st.Cache[:1]
-	st.CacheUseSize = 0
-	return
-}
-
-// Check returns true if a key already exists in the cache.
-func(st *State) Check(key string) bool {
-	return st.frameOf(key) == -1
-}
-
-// Size returns size used by values, and remaining size available
-func(st *State) Size() (uint32, uint32) {
-	var l int
-	var c uint16
-	for k, v := range st.CacheMap {
-		l += len(v)
-		c += st.sizes[k]
-	}
-	r := uint32(l)
-	return r, uint32(c)-r
-}
-
-// Appendcode adds the given bytecode to the end of the existing code.
-func(st *State) AppendCode(b []byte) error {
-	st.code = append(st.code, b...)
-	log.Printf("code changed to 0x%x", b)
-	return nil
-}
-
-// SetCode replaces the current bytecode with the given bytecode.
-func(st *State) SetCode(b []byte) {
-	log.Printf("code set to 0x%x", b)
-	st.code = b
-}
-
-// Get the remaning cached bytecode
-func(st *State) GetCode() ([]byte, error) {
-	b := st.code
-	st.code = []byte{}
-	return b, nil
-}
-
-// GetInput gets the most recent client input.
-func(st *State) GetInput() ([]byte, error) {
-	if st.input == nil {
-		return nil, fmt.Errorf("no input has been set")
-	}
-	return st.input, nil
-}
-
-// SetInput is used to record the latest client input.
-func(st *State) SetInput(input []byte) error {
-	l := len(input)
-	if l > 255 {
-		return fmt.Errorf("input size %v too large (limit %v)", l, 255)
-	}
-	st.input = input
-	return nil
-}
-
-// return 0-indexed frame number where key is defined. -1 if not defined
-func(st *State) frameOf(key string) int {
-	for i, m := range st.Cache {
-		for k, _ := range m {
-			if k == key {
-				return i
-			}
-		}
-	}
-	return -1
-}
-
-// bytes that will be added to cache use size for string
-// returns 0 if capacity would be exceeded
-func(st *State) checkCapacity(v string) uint32 {
-	sz := uint32(len(v))
-	if st.CacheSize == 0 {
-		return sz
-	}
-	if st.CacheUseSize + sz > st.CacheSize {
-		return 0	
-	}
-	return sz
-}
-
-// flush relveant properties for level change
-func(st *State) resetCurrent() {
-	st.sink = nil
-	st.CacheMap = make(map[string]string)
-}

go/state/state_test.go

@@ -1,312 +0,0 @@
-package state
-
-import (
-	"bytes"
-	"testing"
-)
-
-// Check creation 
-func TestNewState(t *testing.T) {
-	st := NewState(5)
-	if len(st.Flags) != 2 {
-		t.Errorf("invalid state flag length: %v", len(st.Flags))
-	}
-	st = NewState(8)
-	if len(st.Flags) != 2 {
-		t.Errorf("invalid state flag length: %v", len(st.Flags))
-	}
-	st = NewState(17)
-	if len(st.Flags) != 4 {
-		t.Errorf("invalid state flag length: %v", len(st.Flags))
-	}
-}
-
-func TestStateFlags(t *testing.T) {
-	st := NewState(9)
-	v, err := st.GetFlag(2)
-	if err != nil {
-		t.Error(err)
-	}
-	if v {
-		t.Errorf("Expected bit 2 not to be set")
-	}
-	v, err = st.SetFlag(2)
-	if err != nil {
-		t.Error(err)
-	}
-	if !v {
-		t.Errorf("Expected change to be set for bit 2")
-	}
-	v, err = st.GetFlag(2)
-	if err != nil {
-		t.Error(err)
-	}
-	if !v {
-		t.Errorf("Expected bit 2 to be set")
-	}
-	v, err = st.SetFlag(10)
-	if err != nil {
-		t.Error(err)
-	}
-	if !v {
-		t.Errorf("Expected change to be set for bit 10")
-	}
-	v, err = st.GetFlag(10)
-	if err != nil {
-		t.Error(err)
-	}
-	if !v {
-		t.Errorf("Expected bit 10 to be set")
-	}
-	v, err = st.ResetFlag(2)
-	if err != nil {
-		t.Error(err)
-	}
-	if !v {
-		t.Errorf("Expected change to be set for bit 10")
-	}
-	v, err = st.GetFlag(2)
-	if err != nil {
-		t.Error(err)
-	}
-	if v {
-		t.Errorf("Expected bit 2 not to be set")
-	}
-	v, err = st.GetFlag(10)
-	if err != nil {
-		t.Error(err)
-	}
-	if !v {
-		t.Errorf("Expected bit 10 to be set")
-	}
-	v, err = st.SetFlag(10)
-	if err != nil {
-		t.Error(err)
-	}
-	if v {
-		t.Errorf("Expected change not to be set for bit 10")
-	}
-	v, err = st.SetFlag(2)
-	if err != nil {
-		t.Error(err)
-	}
-	v, err = st.SetFlag(16)
-	if err != nil {
-		t.Error(err)
-	}
-	v, err = st.SetFlag(17)
-	if err == nil {
-		t.Errorf("Expected out of range for bit index 17")
-	}
-	if !bytes.Equal(st.Flags[:3], []byte{0x04, 0x04, 0x01}) {
-		t.Errorf("Expected 0x040401, got %v", st.Flags[:3])
-	}
-}
-
-func TestStateFlagFromSlice(t *testing.T) {
-	st := NewState(15)
-	_, _= st.SetFlag(2)
-	v := st.GetIndex([]byte{})
-	if v {
-		t.Errorf("Expected no match on empty compare")
-	}
-	v = st.GetIndex([]byte{0x01})
-	if v {
-		t.Errorf("Expected 0x01 not to match")
-	}
-	v = st.GetIndex([]byte{0x04})
-	if !v {
-		t.Errorf("Expected 0x04 to match")
-	}
-	_, _= st.SetFlag(12)
-	v = st.GetIndex([]byte{0x04})
-	if !v {
-		t.Errorf("Expected 0x04 to match")
-	}
-	v = st.GetIndex([]byte{0x00, 0x10})
-	if !v {
-		t.Errorf("Expected 0x1000 to match")
-	}
-	v, _ = st.ResetFlag(2)
-	v = st.GetIndex([]byte{0x00, 0x10})
-	if !v {
-		t.Errorf("Expected 0x1000 to matck")
-	}
-}
-
-//
-func TestNewStateCache(t *testing.T) {
-	st := NewState(17)
-	if st.CacheSize != 0 {
-		t.Errorf("cache size not 0")
-	}
-	st = st.WithCacheSize(102525)
-	if st.CacheSize != 102525 {
-		t.Errorf("cache size not 102525")
-	}
-
-}
-
-func TestStateCacheUse(t *testing.T) {
-	st := NewState(17)
-	st = st.WithCacheSize(10)
-	st.Down("foo")
-	err := st.Add("bar", "baz", 0)
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Add("inky", "pinky", 0)
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Add("blinky", "clyde", 0)
-	if err == nil {
-		t.Errorf("expected capacity error")
-	}
-}
-
-func TestStateDownUp(t *testing.T) {
-	st := NewState(17)
-	st.Down("one")
-	err := st.Add("foo", "bar", 0)
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Add("baz", "xyzzy", 0)
-	if err != nil {
-		t.Error(err)
-	}
-	if st.CacheUseSize != 8 {
-		t.Errorf("expected cache use size 8 got %v", st.CacheUseSize)
-	}
-	err = st.Up()
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Up()
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Up()
-	if err == nil {
-		t.Errorf("expected out of top frame error")
-	}
-}
-
-func TestStateReset(t *testing.T) {
-	st := NewState(17)
-	st.Down("one")
-	err := st.Add("foo", "bar", 0)
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Add("baz", "xyzzy", 0)
-	if err != nil {
-		t.Error(err)
-	}
-	st.Down("two")
-	st.Down("three")
-	st.Reset()
-	if st.CacheUseSize != 0 {
-		t.Errorf("expected cache use size 0, got %v", st.CacheUseSize)
-	}
-	if st.Depth() != 1 {
-		t.Errorf("expected depth 1, got %v", st.Depth())
-	}
-}
-
-func TestStateLoadDup(t *testing.T) {
-	st := NewState(17)
-	st.Down("one")
-	err := st.Add("foo", "bar", 0)
-	if err != nil {
-		t.Error(err)
-	}
-	st.Down("two")
-	err = st.Add("foo", "baz", 0)
-	if err == nil {
-		t.Errorf("expected fail on duplicate load")
-	}
-	st.Up()
-	err = st.Add("foo", "xyzzy", 0)
-	if err != nil {
-		t.Error(err)
-	}
-}
-
-func TestStateCurrentSize(t *testing.T) {
-	st := NewState(17)
-	st.Down("one")
-	err := st.Add("foo", "bar", 0)
-	if err != nil {
-		t.Error(err)
-	}
-	st.Down("two")
-	err = st.Add("bar", "xyzzy", 10)
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Map("bar")
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Add("baz", "inkypinkyblinkyclyde", 51)
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Map("baz")
-	if err != nil {
-		t.Error(err)
-	}
-	l, c := st.Size()
-	if l != 25 {
-		t.Errorf("expected actual length 25, got %v", l)
-	}
-	if c != 36 {
-		t.Errorf("expected actual length 50, got %v", c)
-	}
-}
-
-func TestStateMapSink(t *testing.T) {
-	st := NewState(17)
-	st.Down("one")
-	err := st.Add("foo", "bar", 0)
-	if err != nil {
-		t.Error(err)
-	}
-	st.Down("two")
-	err = st.Add("bar", "xyzzy", 6)
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Add("baz", "bazbaz", 18)
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Add("xyzzy", "plugh", 0)
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Map("foo")
-	if err != nil {
-		t.Error(err)
-	}
-	err = st.Map("xyzzy")
-	if err == nil {
-		t.Errorf("Expected fail on duplicate sink")
-	}
-	err = st.Map("baz")
-	if err != nil {
-		t.Error(err)
-	}
-	st.Down("three")
-	err = st.Map("foo")
-	if err != nil {
-		t.Error(err)
-	}
-	st.Up()
-	err = st.Map("foo")
-	if err != nil {
-		t.Error(err)
-	}
-}

go/testdata/testdata.go

@@ -1,121 +0,0 @@
-package testdata
-
-import (
-	"fmt"
-	"io/ioutil"
-	"os"
-	"path"
-
-	testdataloader "github.com/peteole/testdata-loader"
-
-	"git.defalsify.org/festive/vm"
-)
-
-type genFunc func() error
-
-var (
-	BaseDir = testdataloader.GetBasePath()
-	DataDir = ""
-	dirLock = false	
-)
-
-func out(sym string, b []byte, tpl string) error {
-	fp := path.Join(DataDir, sym)
-	err := ioutil.WriteFile(fp, []byte(tpl), 0644)
-	if err != nil {
-		return err
-	}
-
-	fb := sym + ".bin"
-	fp = path.Join(DataDir, fb)
-	err = ioutil.WriteFile(fp, b, 0644)
-	if err != nil {
-		return err
-	}
-	return nil
-}
-
-func root() error {
-	b := []byte{}
-	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
-	b = vm.NewLine(b, vm.INCMP, []string{"1", "foo"}, nil, nil)
-	b = vm.NewLine(b, vm.INCMP, []string{"2", "bar"}, nil, nil)
-
-	tpl := "hello world"
-
-	return out("root", b, tpl)
-}
-
-func foo() error {
-	b := []byte{}
-	b = vm.NewLine(b, vm.MOUT, []string{"0", "to foo"}, nil, nil)
-	b = vm.NewLine(b, vm.MOUT, []string{"1", "go bar"}, nil, nil)
-	b = vm.NewLine(b, vm.LOAD, []string{"inky"}, []byte{20}, nil)
-	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
-	b = vm.NewLine(b, vm.INCMP, []string{"0", "_"}, nil, nil)
-	b = vm.NewLine(b, vm.INCMP, []string{"1", "baz"}, nil, nil)
-	b = vm.NewLine(b, vm.CATCH, []string{"_catch"}, []byte{1}, []uint8{1})
-
-	tpl := `this is in foo
-
-it has more lines`
-
-	return out("foo", b, tpl)
-}
-
-func bar() error {
-	b := []byte{}
-	b = vm.NewLine(b, vm.LOAD, []string{"pinky"}, []byte{0}, nil)
-	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
-	b = vm.NewLine(b, vm.INCMP, []string{"0", "_home"}, nil, nil)
-
-	tpl := "this is bar - an end node"
-
-	return out("bar", b, tpl)
-}
-
-func baz() error {
-	b := []byte{}
-	b = vm.NewLine(b, vm.MAP, []string{"inky"}, nil, nil)
-	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
-
-	tpl := "this is baz which uses the var {{.inky}} in the template."
-
-	return out("baz", b, tpl)
-}
-
-func generate() error {
-	err := os.MkdirAll(DataDir, 0755)
-	if err != nil {
-		return err
-	}
-
-	fns := []genFunc{root, foo, bar, baz}
-	for _, fn := range fns {
-		err = fn()
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func Generate() (string, error) {
-	dir, err := ioutil.TempDir("", "festive_testdata_")
-	if err != nil {
-		return "", err
-	}
-	DataDir = dir
-	dirLock = true
-	err = generate()
-	return dir, err
-}
-
-func GenerateTo(dir string) error {
-	if dirLock {
-		return fmt.Errorf("directory already overridden")
-	}
-	DataDir = dir
-	dirLock = true
-	return generate()
-}

go/vm/runner.go

@@ -1,246 +0,0 @@
-package vm
-
-import (
-	"context"
-	"fmt"
-	"log"
-
-	"git.defalsify.org/festive/resource"
-	"git.defalsify.org/festive/state"
-)
-
-//type Runner func(instruction []byte, st state.State, rs resource.Resource, ctx context.Context) (state.State, []byte, error)
-
-// Run extracts individual op codes and arguments and executes them.
-//
-// Each step may update the state.
-//
-// On error, the remaining instructions will be returned. State will not be rolled back.
-func Run(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	running := true
-	for running {
-		log.Printf("execute code %x", b)
-		op, bb, err := opSplit(b)
-		if err != nil {
-			return b, err
-		}
-		b = bb
-		switch op {
-		case CATCH:
-			b, err = RunCatch(b, st, rs, ctx)
-		case CROAK:
-			b, err = RunCroak(b, st, rs, ctx)
-		case LOAD:
-			b, err = RunLoad(b, st, rs, ctx)
-		case RELOAD:
-			b, err = RunReload(b, st, rs, ctx)
-		case MAP:
-			b, err = RunMap(b, st, rs, ctx)
-		case MOVE:
-			b, err = RunMove(b, st, rs, ctx)
-		case INCMP:
-			b, err = RunInCmp(b, st, rs, ctx)
-		case MSIZE:
-			b, err = RunMSize(b, st, rs, ctx)
-		case MOUT:
-			b, err = RunMOut(b, st, rs, ctx)
-		case MNEXT:
-			b, err = RunMNext(b, st, rs, ctx)
-		case MPREV:
-			b, err = RunMPrev(b, st, rs, ctx)
-		case HALT:
-			b, err = RunHalt(b, st, rs, ctx)
-			return b, err
-		default:
-			err = fmt.Errorf("Unhandled state: %v", op)
-		}
-		if err != nil {
-			return b, err
-		}
-		if len(b) == 0 {
-			return []byte{}, nil
-		}
-	}
-	return b, nil
-}
-
-// RunMap executes the MAP opcode
-func RunMap(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	sym, b, err := ParseMap(b)
-	err = st.Map(sym)
-	return b, err
-}
-
-// RunMap executes the CATCH opcode
-func RunCatch(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	sym, sig, mode, b, err := ParseCatch(b)
-	if err != nil {
-		return b, err
-	}
-	r, err := matchFlag(st, sig, mode)
-	if err != nil {
-		return b, err
-	}
-	if r {
-		log.Printf("catch at flag %v, moving to %v", sig, sym) //bitField, d)
-		st.Down(sym)
-		b = []byte{}
-	} 
-	return b, nil
-}
-
-// RunMap executes the CROAK opcode
-func RunCroak(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	sig, mode, b, err := ParseCroak(b)
-	if err != nil {
-		return b, err
-	}
-	r, err := matchFlag(st, sig, mode)
-	if err != nil {
-		return b, err
-	}
-	if r {
-		log.Printf("croak at flag %v, purging and moving to top", sig)
-		st.Reset()
-		b = []byte{}
-	}
-	return []byte{}, nil
-}
-
-// RunLoad executes the LOAD opcode
-func RunLoad(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	sym, sz, b, err := ParseLoad(b)
-	if err != nil {
-		return b, err
-	}
-
-	r, err := refresh(sym, rs, ctx)
-	if err != nil {
-		return b, err
-	}
-	err = st.Add(sym, r, uint16(sz))
-	return b, err
-}
-
-// RunLoad executes the RELOAD opcode
-func RunReload(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	sym, b, err := ParseReload(b)
-	if err != nil {
-		return b, err
-	}
-
-	r, err := refresh(sym, rs, ctx)
-	if err != nil {
-		return b, err
-	}
-	st.Update(sym, r)
-	return b, nil
-}
-
-// RunLoad executes the MOVE opcode
-func RunMove(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	sym, b, err := ParseMove(b)
-	if err != nil {
-		return b, err
-	}
-	st.Down(sym)
-	code, err := rs.GetCode(sym)
-	if err != nil {
-		return b, err
-	}
-	log.Printf("loaded additional code: %x", code)
-	b = append(b, code...)
-	return b, nil
-}
-
-// RunIncmp executes the INCMP opcode
-func RunInCmp(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	sym, target, b, err := ParseInCmp(b)
-	if err != nil {
-		return b, err
-	}
-	v, err := st.GetFlag(state.FLAG_INMATCH)
-	if err != nil {
-		return b, err
-	}
-	if v {
-		return b, nil
-	}
-	input, err := st.GetInput()
-	if err != nil {
-		return b, err
-	}
-	if sym == string(input) {
-		log.Printf("input match for '%s'", input)
-		_, err = st.SetFlag(state.FLAG_INMATCH)
-		st.Down(target)
-	}
-	code, err := rs.GetCode(target)
-	if err != nil {
-		return b, err
-	}
-	log.Printf("loaded additional code: %x", code)
-	b = append(b, code...)
-	return b, err
-}
-
-// RunHalt executes the HALT opcode
-func RunHalt(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	var err error
-	b, err = ParseHalt(b)
-	if err != nil {
-		return b, err
-	}
-	log.Printf("found HALT, stopping")
-	_, err = st.ResetFlag(state.FLAG_INMATCH)
-	return b, err
-}
-
-// RunMSize executes the HALT opcode
-func RunMSize(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	log.Printf("WARNING MSIZE not yet implemented")
-	_, _, b, err := ParseMSize(b)
-	return b, err
-}
-
-// RunMNext executes the MNEXT opcode
-func RunMNext(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	selector, display, b, err := ParseMNext(b)
-	if err != nil {
-		return b, err
-	}
-	err = rs.SetMenuBrowse(selector, display, false)
-	return b, err
-}
-
-// RunMPrev executes the MPREV opcode
-func RunMPrev(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	selector, display, b, err := ParseMPrev(b)
-	if err != nil {
-		return b, err
-	}
-	err = rs.SetMenuBrowse(selector, display, false)
-	return b, err
-}
-
-// RunMOut executes the MOUT opcode
-func RunMOut(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
-	choice, title, b, err := ParseMOut(b)
-	if err != nil {
-		return b, err
-	}
-	err = rs.PutMenu(choice, title)
-	return b, err
-}
-
-// retrieve data for key
-func refresh(key string, rs resource.Resource, ctx context.Context) (string, error) {
-	fn, err := rs.FuncFor(key)
-	if err != nil {
-		return "", err
-	}
-	if fn == nil {
-		return "", fmt.Errorf("no retrieve function for external symbol %v", key)
-	}
-	return fn(ctx)
-}

go/vm/runner_test.go

@@ -1,352 +0,0 @@
-package vm
-
-import (
-	"bytes"
-	"context"
-	"fmt"
-	"log"
-	"testing"
-	
-	"git.defalsify.org/festive/resource"
-	"git.defalsify.org/festive/state"
-)
-
-var dynVal = "three"
-
-type TestResource struct {
-	resource.MenuResource
-	state *state.State
-}
-
-func getOne(ctx context.Context) (string, error) {
-	return "one", nil
-}
-
-func getTwo(ctx context.Context) (string, error) {
-	return "two", nil
-}
-
-func getDyn(ctx context.Context) (string, error) {
-	return dynVal, nil
-}
-
-type TestStatefulResolver struct {
-	state *state.State
-}
-
-func (r *TestResource) GetTemplate(sym string) (string, error) {
-	switch sym {
-	case "foo":
-		return "inky pinky blinky clyde", nil
-	case "bar":
-		return "inky pinky {{.one}} blinky {{.two}} clyde", nil
-	case "baz":
-		return "inky pinky {{.baz}} blinky clyde", nil
-	case "three":
-		return "{{.one}} inky pinky {{.three}} blinky clyde {{.two}}", nil
-	case "_catch":
-		return "aiee", nil
-	}
-	panic(fmt.Sprintf("unknown symbol %s", sym))
-	return "", fmt.Errorf("unknown symbol %s", sym)
-}
-
-func (r *TestResource) RenderTemplate(sym string, values map[string]string) (string, error) {
-	return resource.DefaultRenderTemplate(r, sym, values)
-}
-
-func (r *TestResource) FuncFor(sym string) (resource.EntryFunc, error) {
-	switch sym {
-	case "one":
-		return getOne, nil
-	case "two":
-		return getTwo, nil
-	case "dyn":
-		return getDyn, nil
-	case "arg":
-		return r.getInput, nil
-	}
-	return nil, fmt.Errorf("invalid function: '%s'", sym)
-}
-
-func(r *TestResource) getInput(ctx context.Context) (string, error) {
-	v, err := r.state.GetInput()
-	return string(v), err
-}
-
-func(r *TestResource) GetCode(sym string) ([]byte, error) {
-	return []byte{}, nil
-}
-
-func TestRun(t *testing.T) {
-	st := state.NewState(5)
-	rs := TestResource{}
-
-	b := NewLine(nil, MOVE, []string{"foo"}, nil, nil)
-	//b := []byte{0x00, MOVE, 0x03}
-	//b = append(b, []byte("foo")...)
-	_, err := Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Errorf("run error: %v", err)	
-	}
-
-	b = []byte{0x01, 0x02}
-	_, err = Run(b, &st, &rs, context.TODO())
-	if err == nil {
-		t.Errorf("no error on invalid opcode")	
-	}
-}
-
-func TestRunLoadRender(t *testing.T) {
-	st := state.NewState(5)
-	st.Down("barbarbar")
-	rs := TestResource{}
-
-	var err error
-	b := NewLine(nil, LOAD, []string{"one"}, []byte{0x0a}, nil)
-	b, err = Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)
-	}
-	m, err := st.Get()
-	if err != nil {
-		t.Error(err)
-	}
-	r, err := rs.RenderTemplate("foo", m)
-	if err != nil {
-		t.Error(err)
-	}
-	expect := "inky pinky blinky clyde"
-	if r != expect {
-		t.Errorf("Expected %v, got %v", []byte(expect), []byte(r))
-	}
-
-	r, err = rs.RenderTemplate("bar", m)
-	if err == nil {
-		t.Errorf("expected error for render of bar: %v" ,err)
-	}
-
-	b = NewLine(nil, LOAD, []string{"two"}, []byte{0x0a}, nil)
-	b, err = Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)
-	}
-	b = NewLine(nil, MAP, []string{"one"}, nil, nil)
-	_, err = Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)
-	}
-	m, err = st.Get()
-	if err != nil {
-		t.Error(err)
-	}
-	r, err = rs.RenderTemplate("bar", m)
-	if err != nil {
-		t.Error(err)
-	}
-	expect = "inky pinky one blinky two clyde"
-	if r != expect {
-		t.Errorf("Expected %v, got %v", expect, r)
-	}
-}
-
-func TestRunMultiple(t *testing.T) {
-	st := state.NewState(5)
-	rs := TestResource{}
-	b := NewLine(nil, LOAD, []string{"one"}, []byte{0x00}, nil)
-	b = NewLine(b, LOAD, []string{"two"}, []byte{42}, nil)
-	b, err := Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)
-	}
-	if len(b) > 0 {
-		t.Errorf("expected empty code")
-	}
-}
-
-func TestRunReload(t *testing.T) {
-	st := state.NewState(5)
-	rs := TestResource{}
-	b := NewLine(nil, LOAD, []string{"dyn"}, nil, []uint8{0})
-	b = NewLine(b, MAP, []string{"dyn"}, nil, nil)
-	_, err := Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)
-	}
-	r, err := st.Val("dyn")
-	if err != nil {
-		t.Error(err)
-	}
-	if r != "three" {
-		t.Errorf("expected result 'three', got %v", r)
-	}
-	dynVal = "baz"
-	b = []byte{}
-	b = NewLine(b, RELOAD, []string{"dyn"}, nil, nil)
-	_, err = Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)
-	}
-	r, err = st.Val("dyn")
-	if err != nil {
-		t.Error(err)
-	}
-	log.Printf("dun now %s", r)
-	if r != "baz" {
-		t.Errorf("expected result 'baz', got %v", r)
-	}
-
-}
-
-func TestHalt(t *testing.T) {
-	st := state.NewState(5)
-	rs := TestResource{}
-	b := NewLine([]byte{}, LOAD, []string{"one"}, nil, []uint8{0})
-	b = NewLine(b, HALT, nil, nil, nil)
-	b = NewLine(b, MOVE, []string{"foo"}, nil, nil)
-	var err error
-	b, err = Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)
-	}
-	r := st.Where()
-	if r == "foo" {
-		t.Fatalf("Expected where-symbol not to be 'foo'")
-	}
-	if !bytes.Equal(b[:2], []byte{0x00, MOVE}) {
-		t.Fatalf("Expected MOVE instruction, found '%v'", b)
-	}
-}
-
-func TestRunArg(t *testing.T) {
-	st := state.NewState(5)
-	rs := TestResource{}
-	
-	input := []byte("bar")
-	_ = st.SetInput(input)
-
-	bi := NewLine([]byte{}, INCMP, []string{"bar", "baz"}, nil, nil)
-	b, err := Run(bi, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)	
-	}
-	l := len(b)
-	if l != 0 {
-		t.Errorf("expected empty remainder, got length %v: %v", l, b)
-	}
-	r := st.Where()
-	if r != "baz" {
-		t.Errorf("expected where-state baz, got %v", r)
-	}
-}
-
-func TestRunInputHandler(t *testing.T) {
-	st := state.NewState(5)
-	rs := TestResource{}
-
-	_ = st.SetInput([]byte("baz"))
-
-	bi := NewLine([]byte{}, INCMP, []string{"bar", "aiee"}, nil, nil)
-	bi = NewLine(bi, INCMP, []string{"baz", "foo"}, nil, nil)
-	bi = NewLine(bi, LOAD, []string{"one"}, []byte{0x00}, nil)
-	bi = NewLine(bi, LOAD, []string{"two"}, []byte{0x03}, nil)
-	bi = NewLine(bi, MAP, []string{"one"}, nil, nil)
-	bi = NewLine(bi, MAP, []string{"two"}, nil, nil)
-
-	var err error
-	_, err = Run(bi, &st, &rs, context.TODO())
-	if err != nil {
-		t.Fatal(err)	
-	}
-	r := st.Where()
-	if r != "foo" {
-		t.Fatalf("expected where-sym 'foo', got '%v'", r)
-	}
-}
-
-func TestRunArgInvalid(t *testing.T) {
-	st := state.NewState(5)
-	rs := TestResource{}
-
-	_ = st.SetInput([]byte("foo"))
-
-	var err error
-
-	b := NewLine([]byte{}, INCMP, []string{"bar", "baz"}, nil, nil)
-	b = NewLine(b, CATCH, []string{"_catch"}, []byte{state.FLAG_INMATCH}, []uint8{1})
-
-	b, err = Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)	
-	}
-	l := len(b)
-	if l != 0 {
-		t.Errorf("expected empty remainder, got length %v: %v", l, b)
-	}
-	r := st.Where()
-	if r != "_catch" {
-		t.Errorf("expected where-state _catch, got %v", r)
-	}
-}
-
-func TestRunMenu(t *testing.T) {
-	st := state.NewState(5)
-	rs := TestResource{}
-
-	var err error
-
-	b := NewLine(nil, MOVE, []string{"foo"}, nil, nil)
-	b = NewLine(b, MOUT, []string{"0", "one"}, nil, nil)
-	b = NewLine(b, MOUT, []string{"1", "two"}, nil, nil)
-
-	b, err = Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)	
-	}
-	l := len(b)
-	if l != 0 {
-		t.Errorf("expected empty remainder, got length %v: %v", l, b)
-	}
-	
-	r, err := rs.RenderMenu()
-	if err != nil {
-		t.Fatal(err)
-	}
-	expect := "0:one\n1:two"
-	if r != expect {
-		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect, r)
-	}
-}
-
-
-func TestRunMenuBrowse(t *testing.T) {
-	log.Printf("This test is incomplete, it must check the output of a menu browser once one is implemented. For now it only checks whether it can execute the runner endpoints for the instrucitons.")
-	st := state.NewState(5)
-	rs := TestResource{}
-
-	var err error
-
-	b := NewLine(nil, MOVE, []string{"foo"}, nil, nil)
-	b = NewLine(b, MNEXT, []string{"11", "two"}, nil, nil)
-	b = NewLine(b, MPREV, []string{"22", "two"}, nil, nil)
-	b = NewLine(b, MOUT, []string{"0", "one"}, nil, nil)
-	b = NewLine(b, MOUT, []string{"1", "two"}, nil, nil)
-
-	b, err = Run(b, &st, &rs, context.TODO())
-	if err != nil {
-		t.Error(err)	
-	}
-	l := len(b)
-	if l != 0 {
-		t.Errorf("expected empty remainder, got length %v: %v", l, b)
-	}
-	
-	r, err := rs.RenderMenu()
-	if err != nil {
-		t.Fatal(err)
-	}
-	expect := "0:one\n1:two"
-	if r != expect {
-		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect, r)
-	}
-}

persist/doc.go

@@ -0,0 +1,2 @@
+// Package persist enables persistent storage of the execution state.
+package persist

persist/fs.go

@@ -0,0 +1,86 @@
+package persist
+
+import (
+	"io/ioutil"
+	"log"
+	"path"
+	"path/filepath"
+
+	"github.com/fxamacker/cbor/v2"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+// FsPersister is an implementation of Persister that saves state to the file system.
+type FsPersister struct {
+	State  *state.State
+	Memory *cache.Cache
+	dir    string
+}
+
+// NewFsPersister creates a new FsPersister.
+//
+// The filesystem store will be at the given directory. The directory must exist.
+func NewFsPersister(dir string) *FsPersister {
+	fp, err := filepath.Abs(dir)
+	if err != nil {
+		panic(err)
+	}
+	return &FsPersister{
+		dir: fp,
+	}
+}
+
+// WithContent sets a current State and Cache object.
+//
+// This method is normally called before Serialize / Save.
+func (p *FsPersister) WithContent(st *state.State, ca *cache.Cache) *FsPersister {
+	p.State = st
+	p.Memory = ca
+	return p
+}
+
+// GetState implements the Persister interface.
+func (p *FsPersister) GetState() *state.State {
+	return p.State
+}
+
+// GetState implements the Persister interface.
+func (p *FsPersister) GetMemory() cache.Memory {
+	return p.Memory
+}
+
+// GetState implements the Persister interface.
+func (p *FsPersister) Serialize() ([]byte, error) {
+	return cbor.Marshal(p)
+}
+
+// GetState implements the Persister interface.
+func (p *FsPersister) Deserialize(b []byte) error {
+	err := cbor.Unmarshal(b, p)
+	return err
+}
+
+// GetState implements the Persister interface.
+func (p *FsPersister) Save(key string) error {
+	b, err := p.Serialize()
+	if err != nil {
+		return err
+	}
+	fp := path.Join(p.dir, key)
+	log.Printf("saved key %v state %x", key, p.State.Code)
+	return ioutil.WriteFile(fp, b, 0600)
+}
+
+// GetState implements the Persister interface.
+func (p *FsPersister) Load(key string) error {
+	fp := path.Join(p.dir, key)
+	b, err := ioutil.ReadFile(fp)
+	if err != nil {
+		return err
+	}
+	err = p.Deserialize(b)
+	log.Printf("loaded key %v state %x", key, p.State.Code)
+	return err
+}

persist/fs_test.go

@@ -0,0 +1,106 @@
+package persist
+
+import (
+	"bytes"
+	"io/ioutil"
+	"log"
+	"reflect"
+	"testing"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/state"
+	"git.grassecon.net/kamikazechaser/vise/vm"
+)
+
+func TestSerializeState(t *testing.T) {
+	st := state.NewState(12)
+	st.Down("foo")
+	st.Down("bar")
+	st.Down("baz")
+	st.Next()
+	st.Next()
+
+	b := vm.NewLine(nil, vm.LOAD, []string{"foo"}, []byte{42}, nil)
+	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
+	st.SetCode(b)
+
+	ca := cache.NewCache().WithCacheSize(1024)
+	ca.Add("inky", "pinky", 13)
+	ca.Add("blinky", "clyde", 42)
+
+	pr := NewFsPersister(".").WithContent(&st, ca)
+	v, err := pr.Serialize()
+	if err != nil {
+		t.Error(err)
+	}
+	log.Printf("v %b", v)
+
+	prnew := NewFsPersister(".")
+	err = prnew.Deserialize(v)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !reflect.DeepEqual(prnew.State.ExecPath, pr.State.ExecPath) {
+		t.Fatalf("expected %s, got %s", prnew.State.ExecPath, pr.State.ExecPath)
+	}
+	if !bytes.Equal(prnew.State.Code, pr.State.Code) {
+		t.Fatalf("expected %x, got %x", prnew.State.Code, pr.State.Code)
+	}
+	if prnew.State.BitSize != pr.State.BitSize {
+		t.Fatalf("expected %v, got %v", prnew.State.BitSize, pr.State.BitSize)
+	}
+	if prnew.State.SizeIdx != pr.State.SizeIdx {
+		t.Fatalf("expected %v, got %v", prnew.State.SizeIdx, pr.State.SizeIdx)
+	}
+	if !reflect.DeepEqual(prnew.Memory, pr.Memory) {
+		t.Fatalf("expected %v, got %v", prnew.Memory, pr.Memory)
+	}
+}
+
+func TestSaveLoad(t *testing.T) {
+	st := state.NewState(12)
+	st.Down("foo")
+	st.Down("bar")
+	st.Down("baz")
+	st.Next()
+	st.Next()
+
+	b := vm.NewLine(nil, vm.LOAD, []string{"foo"}, []byte{42}, nil)
+	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
+	st.SetCode(b)
+
+	ca := cache.NewCache().WithCacheSize(1024)
+	ca.Add("inky", "pinky", 13)
+	ca.Add("blinky", "clyde", 42)
+
+	dir, err := ioutil.TempDir("", "vise_persist")
+	if err != nil {
+		t.Error(err)
+	}
+	pr := NewFsPersister(dir).WithContent(&st, ca)
+	err = pr.Save("xyzzy")
+	if err != nil {
+		t.Error(err)
+	}
+
+	prnew := NewFsPersister(dir)
+	err = prnew.Load("xyzzy")
+	if err != nil {
+		t.Error(err)
+	}
+	if !reflect.DeepEqual(prnew.State.ExecPath, pr.State.ExecPath) {
+		t.Fatalf("expected %s, got %s", prnew.State.ExecPath, pr.State.ExecPath)
+	}
+	if !bytes.Equal(prnew.State.Code, pr.State.Code) {
+		t.Fatalf("expected %x, got %x", prnew.State.Code, pr.State.Code)
+	}
+	if prnew.State.BitSize != pr.State.BitSize {
+		t.Fatalf("expected %v, got %v", prnew.State.BitSize, pr.State.BitSize)
+	}
+	if prnew.State.SizeIdx != pr.State.SizeIdx {
+		t.Fatalf("expected %v, got %v", prnew.State.SizeIdx, pr.State.SizeIdx)
+	}
+	if !reflect.DeepEqual(prnew.Memory, pr.Memory) {
+		t.Fatalf("expected %v, got %v", prnew.Memory, pr.Memory)
+	}
+}

persist/persist.go

@@ -0,0 +1,16 @@
+package persist
+
+import (
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+// Persister interface defines the methods needed for a component that can store the execution state to a storage location.
+type Persister interface {
+	Serialize() ([]byte, error) // Output serializes representation of the state.
+	Deserialize(b []byte) error // Restore state from a serialized state.
+	Save(key string) error      // Serialize and commit the state representation to persisted storage.
+	Load(key string) error      // Load the state representation from persisted storage and Deserialize.
+	GetState() *state.State     // Get the currently loaded State object.
+	GetMemory() cache.Memory    // Get the currently loaded Cache object.
+}

render/doc.go

@@ -0,0 +1,2 @@
+// Package render handles output size constraints and paginated rendering of contents and menus against templates.
+package render

render/menu.go

@@ -0,0 +1,181 @@
+package render
+
+import (
+	"fmt"
+)
+
+// BrowseError is raised when browsing outside the page range of a rendered node.
+type BrowseError struct {
+	Idx uint16
+	PageCount uint16
+}
+
+// Error implements the Error interface.
+func(err *BrowseError) Error() string {
+	return fmt.Sprintf("index is out of bounds: %v", err.Idx)
+}
+
+// BrowseConfig defines the availability and display parameters for page browsing.
+type BrowseConfig struct {
+	NextAvailable bool
+	NextSelector string
+	NextTitle string
+	PreviousAvailable bool
+	PreviousSelector string
+	PreviousTitle string
+}
+
+// Default browse settings for convenience.
+func DefaultBrowseConfig() BrowseConfig {
+	return BrowseConfig{
+		NextAvailable: true,
+		NextSelector: "11",
+		NextTitle: "next",
+		PreviousAvailable: true,
+		PreviousSelector: "22",
+		PreviousTitle: "previous",
+	}
+}
+
+// Menu renders menus. May be included in a Page object to render menus for pages.
+type Menu struct {
+	menu [][2]string // selector and title for menu items.
+	browse BrowseConfig // browse definitions.
+	pageCount uint16 // number of pages the menu should represent.
+	canNext bool // availability flag for the "next" browse option.
+	canPrevious bool // availability flag for the "previous" browse option.
+	outputSize uint16 // maximum size constraint for the menu.
+}
+
+// NewMenu creates a new Menu with an explicit page count.
+func NewMenu() *Menu {
+	return &Menu{}
+}
+
+// WithBrowseConfig defines the criteria for page browsing.
+func(m *Menu) WithPageCount(pageCount uint16) *Menu {
+	m.pageCount = pageCount
+	return m
+}
+
+// WithSize defines the maximum byte size of the rendered menu.
+func(m *Menu) WithOutputSize(outputSize uint16) *Menu {
+	m.outputSize = outputSize
+	return m
+}
+
+// GetOutputSize returns the defined heuristic menu size.
+func(m *Menu) GetOutputSize() uint32 {
+	return uint32(m.outputSize)
+}
+
+// WithBrowseConfig defines the criteria for page browsing.
+func(m *Menu) WithBrowseConfig(cfg BrowseConfig) *Menu {
+	m.browse = cfg
+	return m
+}
+
+// GetBrowseConfig returns a copy of the current state of the browse configuration.
+func(m *Menu) GetBrowseConfig() BrowseConfig {
+	return m.browse
+}
+
+// Put adds a menu option to the menu rendering.
+func(m *Menu) Put(selector string, title string) error {
+	m.menu = append(m.menu, [2]string{selector, title})
+	return nil
+}
+
+// ReservedSize returns the maximum render byte size of the menu.
+func(m *Menu) ReservedSize() uint16 {
+	return m.outputSize
+}
+
+// Render returns the full current state of the menu as a string.
+//
+// After this has been executed, the state of the menu will be empty.
+func(m *Menu) Render(idx uint16) (string, error) {
+	var menuCopy [][2]string
+	for _, v := range m.menu {
+		menuCopy = append(menuCopy, v)
+	}
+
+	err := m.applyPage(idx)
+	if err != nil {
+		return "", err
+	}
+
+	r := ""
+	for true {
+		l := len(r)
+		choice, title, err := m.shiftMenu()
+		if err != nil {
+			break
+		}
+		if l > 0 {
+			r += "\n"
+		}
+		r += fmt.Sprintf("%s:%s", choice, title)
+	}
+	m.menu = menuCopy
+	return r, nil
+}
+
+// add available browse options.
+func(m *Menu) applyPage(idx uint16) error {
+	if m.pageCount == 0 {
+		if idx > 0 {
+			return fmt.Errorf("index %v > 0 for non-paged menu", idx)
+		}
+		return nil
+	} else if idx >= m.pageCount {
+		return &BrowseError{Idx: idx, PageCount: m.pageCount}
+		//return fmt.Errorf("index %v out of bounds (%v)", idx, m.pageCount)
+	}
+	
+	m.reset()
+
+	if idx == m.pageCount - 1 {
+		m.canNext = false
+	}
+	if idx == 0 {
+		m.canPrevious = false
+	}
+
+	if m.canNext {
+		err := m.Put(m.browse.NextSelector, m.browse.NextTitle)
+		if err != nil {
+			return err
+		}
+	}
+	if m.canPrevious {
+		err := m.Put(m.browse.PreviousSelector, m.browse.PreviousTitle)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// removes and returns the first of remaining menu options.
+// fails if menu is empty.
+func(m *Menu) shiftMenu() (string, string, error) {
+	if len(m.menu) == 0 {
+		return "", "", fmt.Errorf("menu is empty")
+	}
+	r := m.menu[0]
+	m.menu = m.menu[1:]
+	return r[0], r[1], nil
+}
+
+// prepare menu object for re-use.
+func(m *Menu) reset() {
+	if m.browse.NextAvailable {
+		m.canNext = true
+	}
+	if m.browse.PreviousAvailable {
+		m.canPrevious = true
+	}
+}
+
+

render/menu_test.go

@@ -0,0 +1,84 @@
+package render
+
+import (
+	"testing"
+)
+
+func TestMenuInit(t *testing.T) {
+	m := NewMenu()
+	err := m.Put("1", "foo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = m.Put("2", "bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+	r, err := m.Render(0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expect := `1:foo
+2:bar`
+	if r != expect {
+		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect, r)
+	}
+
+	r, err = m.Render(1)
+	if err == nil {
+		t.Fatalf("expected render fail")
+	}
+
+}
+
+func TestMenuBrowse(t *testing.T) {
+	cfg := DefaultBrowseConfig()
+	m := NewMenu().WithPageCount(3).WithBrowseConfig(cfg)
+	err := m.Put("1", "foo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = m.Put("2", "bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	r, err := m.Render(0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expect := `1:foo
+2:bar
+11:next`
+	if r != expect {
+		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect, r)
+	}
+
+	r, err = m.Render(1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expect = `1:foo
+2:bar
+11:next
+22:previous`
+	if r != expect {
+		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect, r)
+	}
+
+	r, err = m.Render(2)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expect = `1:foo
+2:bar
+22:previous`
+	if r != expect {
+		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect, r)
+	}
+
+	_, err = m.Render(3)
+	if err == nil {
+		t.Fatalf("expected render fail")
+	}
+}

render/page.go

@@ -0,0 +1,333 @@
+package render
+
+import (
+	"bytes"
+	"fmt"
+	"log"
+	"strings"
+	"text/template"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/resource"
+)
+
+// Page exectues output rendering into pages constrained by size.
+type Page struct {
+	cacheMap map[string]string // Mapped content symbols
+	cache    cache.Memory      // Content store.
+	resource resource.Resource // Symbol resolver.
+	menu     *Menu             // Menu rendererer.
+	sink     *string           // Content symbol rendered by dynamic size.
+	sizer    *Sizer            // Process size constraints.
+}
+
+// NewPage creates a new Page object.
+func NewPage(cache cache.Memory, rs resource.Resource) *Page {
+	return &Page{
+		cache:    cache,
+		cacheMap: make(map[string]string),
+		resource: rs,
+	}
+}
+
+// WithMenu sets a menu renderer for the page.
+func (pg *Page) WithMenu(menu *Menu) *Page {
+	pg.menu = menu
+	if pg.sizer != nil {
+		pg.sizer = pg.sizer.WithMenuSize(pg.menu.ReservedSize())
+	}
+	return pg
+}
+
+// WithSizer sets a size constraints definition for the page.
+func (pg *Page) WithSizer(sizer *Sizer) *Page {
+	pg.sizer = sizer
+	if pg.menu != nil {
+		pg.sizer = pg.sizer.WithMenuSize(pg.menu.ReservedSize())
+	}
+	return pg
+}
+
+// Usage returns size used by values and menu, and remaining size available
+func (pg *Page) Usage() (uint32, uint32, error) {
+	var l int
+	var c uint16
+	for k, v := range pg.cacheMap {
+		l += len(v)
+		sz, err := pg.cache.ReservedSize(k)
+		if err != nil {
+			return 0, 0, err
+		}
+		c += sz
+		log.Printf("v %x %v %v %v %v", []byte(v), len(v), l, sz, c)
+	}
+	r := uint32(l)
+	rsv := uint32(c) - r
+	if pg.menu != nil {
+		r += uint32(pg.menu.ReservedSize())
+	}
+	return r, rsv, nil
+}
+
+// Map marks the given key for retrieval.
+//
+// After this, Val() will return the value for the key, and Size() will include the value size and limitations in its calculations.
+//
+// Only one symbol with no size limitation may be mapped at the current level.
+func (pg *Page) Map(key string) error {
+	v, err := pg.cache.Get(key)
+	if err != nil {
+		return err
+	}
+	l, err := pg.cache.ReservedSize(key)
+	if err != nil {
+		return err
+	}
+	if l == 0 {
+		if pg.sink != nil && *pg.sink != key {
+			return fmt.Errorf("sink already set to symbol '%v'", *pg.sink)
+		}
+		pg.sink = &key
+	}
+	pg.cacheMap[key] = v
+	if pg.sizer != nil {
+		err := pg.sizer.Set(key, l)
+		if err != nil {
+			return err
+		}
+	}
+	log.Printf("mapped %s", key)
+	return nil
+}
+
+// Val gets the mapped content for the given symbol.
+//
+// Fails if key is not mapped.
+func (pg *Page) Val(key string) (string, error) {
+	r := pg.cacheMap[key]
+	if len(r) == 0 {
+		return "", fmt.Errorf("key %v not mapped", key)
+	}
+	return r, nil
+}
+
+// Sizes returned the actual used bytes by each mapped symbol.
+func (pg *Page) Sizes() (map[string]uint16, error) {
+	sizes := make(map[string]uint16)
+	var haveSink bool
+	for k, _ := range pg.cacheMap {
+		l, err := pg.cache.ReservedSize(k)
+		if err != nil {
+			return nil, err
+		}
+		if l == 0 {
+			if haveSink {
+				panic(fmt.Sprintf("duplicate sink for %v", k))
+			}
+			haveSink = true
+		}
+	}
+	return sizes, nil
+}
+
+// RenderTemplate is an adapter to implement the builtin golang text template renderer as resource.RenderTemplate.
+func (pg *Page) RenderTemplate(sym string, values map[string]string, idx uint16) (string, error) {
+	tpl, err := pg.resource.GetTemplate(sym)
+	if err != nil {
+		return "", err
+	}
+	if pg.sizer != nil {
+		values, err = pg.sizer.GetAt(values, idx)
+		if err != nil {
+			return "", err
+		}
+	} else if idx > 0 {
+		return "", fmt.Errorf("sizer needed for indexed render")
+	}
+	log.Printf("render for index: %v", idx)
+
+	tp, err := template.New("tester").Option("missingkey=error").Parse(tpl)
+	if err != nil {
+		return "", err
+	}
+
+	b := bytes.NewBuffer([]byte{})
+	err = tp.Execute(b, values)
+	if err != nil {
+		return "", err
+	}
+	return b.String(), err
+}
+
+// Render renders the current mapped content and menu state against the template associated with the symbol.
+func (pg *Page) Render(sym string, idx uint16) (string, error) {
+	var err error
+
+	values, err := pg.prepare(sym, pg.cacheMap, idx)
+	if err != nil {
+		return "", err
+	}
+
+	return pg.render(sym, values, idx)
+}
+
+// Reset prepared the Page object for re-use.
+//
+// It clears mappings and removes the sink definition.
+func (pg *Page) Reset() {
+	pg.sink = nil
+	pg.cacheMap = make(map[string]string)
+}
+
+// render menu and all syms except sink, split sink into display chunks
+// TODO: Function too long, split up
+func (pg *Page) prepare(sym string, values map[string]string, idx uint16) (map[string]string, error) {
+	var sink string
+
+	if pg.sizer == nil {
+		return values, nil
+	}
+
+	var sinkValues []string
+	noSinkValues := make(map[string]string)
+	for k, v := range values {
+		sz, err := pg.cache.ReservedSize(k)
+		if err != nil {
+			return nil, err
+		}
+		if sz == 0 {
+			sink = k
+			sinkValues = strings.Split(v, "\n")
+			v = ""
+			log.Printf("found sink %s with field count %v", k, len(sinkValues))
+		}
+		noSinkValues[k] = v
+	}
+
+	if sink == "" {
+		log.Printf("no sink found for sym %s", sym)
+		return values, nil
+	}
+
+	pg.sizer.AddCursor(0)
+	s, err := pg.render(sym, noSinkValues, 0)
+	if err != nil {
+		return nil, err
+	}
+	// remaining includes core menu
+	remaining, ok := pg.sizer.Check(s)
+	if !ok {
+		return nil, fmt.Errorf("capacity exceeded")
+	}
+
+	var menuSizes [4]uint32 // mainSize, prevsize, nextsize, nextsize+prevsize
+	if pg.menu != nil {
+		cfg := pg.menu.GetBrowseConfig()
+		tmpm := NewMenu().WithBrowseConfig(cfg)
+		v, err := tmpm.Render(0)
+		if err != nil {
+			return nil, err
+		}
+		menuSizes[0] = uint32(len(v))
+		tmpm = tmpm.WithPageCount(2)
+		v, err = tmpm.Render(0)
+		if err != nil {
+			return nil, err
+		}
+		menuSizes[1] = uint32(len(v)) - menuSizes[0]
+		v, err = tmpm.Render(1)
+		if err != nil {
+			return nil, err
+		}
+		menuSizes[2] = uint32(len(v)) - menuSizes[0]
+		menuSizes[3] = menuSizes[1] + menuSizes[2]
+	}
+
+	log.Printf("%v bytes available for sink split before navigation", remaining)
+
+	l := 0
+	var count uint16
+	tb := strings.Builder{}
+	rb := strings.Builder{}
+
+	netRemaining := remaining - 1
+	if len(sinkValues) > 1 {
+		netRemaining -= menuSizes[1] - 1
+	}
+
+	for i, v := range sinkValues {
+		l += len(v)
+		log.Printf("processing sinkvalue %v: %s", i, v)
+		if uint32(l) > netRemaining-1 {
+			if tb.Len() == 0 {
+				return nil, fmt.Errorf("capacity insufficient for sink field %v", i)
+			}
+			rb.WriteString(tb.String())
+			rb.WriteRune('\n')
+			c := uint32(rb.Len())
+			pg.sizer.AddCursor(c)
+			tb.Reset()
+			l = 0
+			if count == 0 {
+				netRemaining -= menuSizes[2]
+			}
+			count += 1
+		}
+		if tb.Len() > 0 {
+			tb.WriteByte(byte(0x00))
+			l += 1
+		}
+		tb.WriteString(v)
+	}
+
+	if tb.Len() > 0 {
+		rb.WriteString(tb.String())
+		count += 1
+	}
+
+	r := rb.String()
+	r = strings.TrimRight(r, "\n")
+
+	noSinkValues[sink] = r
+
+	if pg.menu != nil {
+		pg.menu = pg.menu.WithPageCount(count)
+	}
+
+	for i, v := range strings.Split(r, "\n") {
+		log.Printf("nosinkvalue %v: %s", i, v)
+	}
+
+	return noSinkValues, nil
+}
+
+// render template, menu (if it exists), and audit size constraint (if it exists).
+func (pg *Page) render(sym string, values map[string]string, idx uint16) (string, error) {
+	var ok bool
+	r := ""
+	s, err := pg.RenderTemplate(sym, values, idx)
+	if err != nil {
+		return "", err
+	}
+	log.Printf("rendered %v bytes for template", len(s))
+	r += s
+
+	if pg.menu != nil {
+		s, err = pg.menu.Render(idx)
+		if err != nil {
+			return "", err
+		}
+		log.Printf("rendered %v bytes for menu", len(s))
+		if len(s) > 0 {
+			r += "\n" + s
+		}
+	}
+
+	if pg.sizer != nil {
+		_, ok = pg.sizer.Check(r)
+		if !ok {
+			return "", fmt.Errorf("limit exceeded: %v", pg.sizer)
+		}
+	}
+	return r, nil
+}

render/page_test.go

@@ -0,0 +1,114 @@
+package render
+
+import (
+	"testing"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+)
+
+func TestPageCurrentSize(t *testing.T) {
+	t.Skip("usage is not in use, and it is unclear how it should be calculated")
+	ca := cache.NewCache()
+	pg := NewPage(ca, nil)
+	err := ca.Push()
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Add("foo", "inky", 0)
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Push()
+	pg.Reset()
+	err = ca.Add("bar", "pinky", 10)
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Add("baz", "tinkywinkydipsylalapoo", 51)
+	if err != nil {
+		t.Error(err)
+	}
+	err = pg.Map("foo")
+	if err != nil {
+		t.Error(err)
+	}
+	err = pg.Map("bar")
+	if err != nil {
+		t.Error(err)
+	}
+	err = pg.Map("baz")
+	if err != nil {
+		t.Error(err)
+	}
+	l, c, err := pg.Usage()
+	if err != nil {
+		t.Error(err)
+	}
+	if l != 27 {
+		t.Errorf("expected actual length 27, got %v", l)
+	}
+	if c != 34 {
+		t.Errorf("expected remaining length 34, got %v", c)
+	}
+
+	mn := NewMenu().WithOutputSize(32)
+	pg = pg.WithMenu(mn)
+	l, c, err = pg.Usage()
+	if err != nil {
+		t.Error(err)
+	}
+	if l != 59 {
+		t.Errorf("expected actual length 59, got %v", l)
+	}
+	if c != 2 {
+		t.Errorf("expected remaining length 2, got %v", c)
+	}
+}
+
+func TestStateMapSink(t *testing.T) {
+	ca := cache.NewCache()
+	pg := NewPage(ca, nil)
+	ca.Push()
+	err := ca.Add("foo", "bar", 0)
+	if err != nil {
+		t.Error(err)
+	}
+	ca.Push()
+	pg.Reset()
+	err = ca.Add("bar", "xyzzy", 6)
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Add("baz", "bazbaz", 18)
+	if err != nil {
+		t.Error(err)
+	}
+	err = ca.Add("xyzzy", "plugh", 0)
+	if err != nil {
+		t.Error(err)
+	}
+	err = pg.Map("foo")
+	if err != nil {
+		t.Error(err)
+	}
+	err = pg.Map("xyzzy")
+	if err == nil {
+		t.Errorf("Expected fail on duplicate sink")
+	}
+	err = pg.Map("baz")
+	if err != nil {
+		t.Error(err)
+	}
+	ca.Push()
+	pg.Reset()
+	err = pg.Map("foo")
+	if err != nil {
+		t.Error(err)
+	}
+	ca.Pop()
+	pg.Reset()
+	err = pg.Map("foo")
+	if err != nil {
+		t.Error(err)
+	}
+}

render/size.go

@@ -0,0 +1,114 @@
+package render
+
+import (
+	"bytes"
+	"fmt"
+	"log"
+	"strings"
+)
+
+// Sizer splits dynamic contents into individual segments for browseable pages.
+type Sizer struct {
+	outputSize uint32 // maximum output for a single page.
+	menuSize uint16 // actual menu size for the dynamic page being sized
+	memberSizes map[string]uint16 // individual byte sizes of all content to be rendered by template.
+	totalMemberSize uint32 // total byte size of all content to be rendered by template (sum of memberSizes)
+	crsrs []uint32 // byte offsets in the sink content for browseable pages indices.
+	sink string // sink symbol.
+}
+
+// NewSizer creates a new Sizer object with the given output size constraint.
+func NewSizer(outputSize uint32) *Sizer {
+	return &Sizer{
+		outputSize: outputSize,
+		memberSizes: make(map[string]uint16),
+	}
+}
+
+// WithMenuSize sets the size of the menu being used in the rendering context.
+func(szr *Sizer) WithMenuSize(menuSize uint16) *Sizer {
+	szr.menuSize = menuSize
+	return szr
+}
+
+// Set adds a content symbol in the state it will be used by the renderer.
+func(szr *Sizer) Set(key string, size uint16) error {
+	szr.memberSizes[key] = size
+	if size == 0 {
+		szr.sink = key
+	}
+	szr.totalMemberSize += uint32(size)
+	return nil
+}
+
+// Check audits whether the rendered string is within the output size constraint of the sizer.
+func(szr *Sizer) Check(s string) (uint32, bool) {
+	l := uint32(len(s))
+	if szr.outputSize > 0 {
+		if l > szr.outputSize {
+			log.Printf("sizer check fails with length %v: %s", l, szr)
+			log.Printf("sizer contents:\n%s", s)
+			return 0, false
+		}
+		l = szr.outputSize - l
+	}
+	return l, true
+}
+
+// String implements the String interface.
+func(szr *Sizer) String() string {
+	var diff uint32
+	if szr.outputSize > 0 {
+		diff = szr.outputSize - szr.totalMemberSize - uint32(szr.menuSize)
+	}
+	return fmt.Sprintf("output: %v, member: %v, menu: %v, diff: %v", szr.outputSize, szr.totalMemberSize, szr.menuSize, diff)
+}
+
+// Size gives the byte size of content for a single symbol.
+//
+// Fails if the symbol has not been registered using Set
+func(szr *Sizer) Size(s string) (uint16, error) {
+	r, ok := szr.memberSizes[s]
+	if !ok {
+		return 0, fmt.Errorf("unknown member: %s", s)
+	}
+	return r, nil
+}
+
+// Menusize returns the currently defined menu size.
+func(szr *Sizer) MenuSize() uint16 {
+	return szr.menuSize
+}
+
+// AddCursor adds a pagination cursor for the paged sink content.
+func(szr *Sizer) AddCursor(c uint32) {
+	log.Printf("added cursor: %v", c)
+	szr.crsrs = append(szr.crsrs, c)
+}
+
+// GetAt the paged symbols for the current page index.
+//
+// Fails if index requested is out of range.
+func(szr *Sizer) GetAt(values map[string]string, idx uint16) (map[string]string, error) {
+	if szr.sink == "" {
+		return values, nil
+	}
+	outValues := make(map[string]string)
+	for k, v := range values {
+		if szr.sink == k {
+			if idx >= uint16(len(szr.crsrs)) {
+				return nil, fmt.Errorf("no more values in index") 
+			}
+			c := szr.crsrs[idx]
+			v = v[c:]
+			nl := strings.Index(v, "\n")
+			if nl > 0 {
+				v = v[:nl]
+			}
+			b := bytes.ReplaceAll([]byte(v), []byte{0x00}, []byte{0x0a})
+			v = string(b)
+		}
+		outValues[k] = v
+	}
+	return outValues, nil
+}

render/size_test.go

@@ -0,0 +1,251 @@
+package render
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/resource"
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+type TestSizeResource struct {
+	*resource.MenuResource
+}
+
+func getTemplate(sym string) (string, error) {
+	var tpl string
+	switch sym {
+	case "small":
+		tpl = "one {{.foo}} two {{.bar}} three {{.baz}}"
+	case "toobig":
+		tpl = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus in mattis lorem. Aliquam erat volutpat. Ut vitae metus."
+	case "pages":
+		tpl = "one {{.foo}} two {{.bar}} three {{.baz}}\n{{.xyzzy}}"
+	}
+	return tpl, nil
+}
+
+func funcFor(sym string) (resource.EntryFunc, error) {
+	switch sym {
+	case "foo":
+		return getFoo, nil
+	case "bar":
+		return getBar, nil
+	case "baz":
+		return getBaz, nil
+	case "xyzzy":
+		return getXyzzy, nil
+	}
+	return nil, fmt.Errorf("unknown func: %s", sym)
+}
+
+func getFoo(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	return resource.Result{
+		Content: "inky",
+	}, nil
+}
+
+func getBar(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	return resource.Result{
+		Content: "pinky",
+	}, nil
+}
+
+func getBaz(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	return resource.Result{
+		Content: "blinky",
+	}, nil
+}
+
+func getXyzzy(sym string, input []byte, ctx context.Context) (resource.Result, error) {
+	return resource.Result{
+		Content: "inky pinky\nblinky clyde sue\ntinkywinky dipsy\nlala poo\none two three four five six seven\neight nine ten\neleven twelve",
+	}, nil
+}
+
+func TestSizeCheck(t *testing.T) {
+	szr := NewSizer(16)
+	l, ok := szr.Check("foobar")
+	if !ok {
+		t.Fatalf("expected ok")
+	}
+	if l != 10 {
+		t.Fatalf("expected 10, got %v", l)
+	}
+
+	l, ok = szr.Check("inkypinkyblinkyclyde")
+	if ok {
+		t.Fatalf("expected not ok")
+	}
+	if l != 0 {
+		t.Fatalf("expected 0, got %v", l)
+	}
+}
+
+func TestSizeLimit(t *testing.T) {
+	st := state.NewState(0)
+	ca := cache.NewCache()
+	mn := NewMenu().WithOutputSize(32)
+	mrs := resource.NewMenuResource().WithEntryFuncGetter(funcFor).WithTemplateGetter(getTemplate)
+	rs := TestSizeResource{
+		mrs,
+	}
+	szr := NewSizer(128)
+	pg := NewPage(ca, rs).WithMenu(mn).WithSizer(szr)
+	ca.Push()
+	st.Down("test")
+	err := ca.Add("foo", "inky", 4)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = ca.Add("bar", "pinky", 10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = ca.Add("baz", "blinky", 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = pg.Map("foo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = pg.Map("bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = pg.Map("baz")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	mn.Put("1", "foo the foo")
+	mn.Put("2", "go to bar")
+
+	_, err = pg.Render("small", 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = pg.Render("toobig", 0)
+	if err == nil {
+		t.Fatalf("expected size exceeded")
+	}
+}
+
+func TestSizePages(t *testing.T) {
+	st := state.NewState(0)
+	ca := cache.NewCache()
+	mn := NewMenu().WithOutputSize(32)
+	mrs := resource.NewMenuResource().WithEntryFuncGetter(funcFor).WithTemplateGetter(getTemplate)
+	rs := TestSizeResource{
+		mrs,
+	}
+	szr := NewSizer(128)
+	pg := NewPage(ca, rs).WithSizer(szr).WithMenu(mn)
+	ca.Push()
+	st.Down("test")
+	ca.Add("foo", "inky", 4)
+	ca.Add("bar", "pinky", 10)
+	ca.Add("baz", "blinky", 20)
+	ca.Add("xyzzy", "inky pinky\nblinky clyde sue\ntinkywinky dipsy\nlala poo\none two three four five six seven\neight nine ten\neleven twelve", 0)
+	pg.Map("foo")
+	pg.Map("bar")
+	pg.Map("baz")
+	pg.Map("xyzzy")
+
+	mn.Put("1", "foo the foo")
+	mn.Put("2", "go to bar")
+
+	r, err := pg.Render("pages", 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expect := `one inky two pinky three blinky
+inky pinky
+blinky clyde sue
+tinkywinky dipsy
+lala poo
+1:foo the foo
+2:go to bar`
+
+	if r != expect {
+		t.Fatalf("expected:\n\t%x\ngot:\n\t%x\n", expect, r)
+	}
+	r, err = pg.Render("pages", 1)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expect = `one inky two pinky three blinky
+one two three four five six seven
+eight nine ten
+eleven twelve
+1:foo the foo
+2:go to bar`
+	if r != expect {
+		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect, r)
+	}
+
+}
+
+func TestManySizes(t *testing.T) {
+	for i := 60; i < 160; i++ {
+		st := state.NewState(0)
+		ca := cache.NewCache()
+		mn := NewMenu().WithOutputSize(32)
+		mrs := resource.NewMenuResource().WithEntryFuncGetter(funcFor).WithTemplateGetter(getTemplate)
+		rs := TestSizeResource{
+			mrs,
+		}
+		szr := NewSizer(uint32(i))
+		pg := NewPage(ca, rs).WithSizer(szr).WithMenu(mn)
+		ca.Push()
+		st.Down("pages")
+		ca.Add("foo", "inky", 10)
+		ca.Add("bar", "pinky", 10)
+		ca.Add("baz", "blinky", 10)
+		ca.Add("xyzzy", "inky pinky\nblinky clyde sue\ntinkywinky dipsy\nlala poo\none two three four five six seven\neight nine ten\neleven twelve", 0)
+		pg.Map("foo")
+		pg.Map("bar")
+		pg.Map("baz")
+		pg.Map("xyzzy")
+		_, err := pg.Render("pages", 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+func TestManySizesMenued(t *testing.T) {
+	for i := 60; i < 160; i++ {
+		st := state.NewState(0)
+		ca := cache.NewCache()
+		mn := NewMenu().WithOutputSize(32)
+		mrs := resource.NewMenuResource().WithEntryFuncGetter(funcFor).WithTemplateGetter(getTemplate)
+		rs := TestSizeResource{
+			mrs,
+		}
+		szr := NewSizer(uint32(i))
+		pg := NewPage(ca, rs).WithSizer(szr).WithMenu(mn)
+		ca.Push()
+		st.Down("pages")
+		ca.Add("foo", "inky", 10)
+		ca.Add("bar", "pinky", 10)
+		ca.Add("baz", "blinky", 10)
+		ca.Add("xyzzy", "inky pinky\nblinky clyde sue\ntinkywinky dipsy\nlala poo\none two three four five six seven\neight nine ten\neleven twelve", 0)
+		pg.Map("foo")
+		pg.Map("bar")
+		pg.Map("baz")
+		pg.Map("xyzzy")
+		mn.Put("0", "yay")
+		mn.Put("12", "nay")
+		_, err := pg.Render("pages", 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+}

resource/doc.go

@@ -0,0 +1,2 @@
+// Package resource interfaces retrieval of bytecode, output templates and external code execution.
+package resource

resource/fs.go

@@ -0,0 +1,81 @@
+package resource
+
+import (
+	"context"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"path"
+	"path/filepath"
+	"strings"
+)
+
+type FsResource struct {
+	MenuResource
+	Path string
+	fns map[string]EntryFunc
+}
+
+func NewFsResource(path string) (FsResource) {
+	absPath, err := filepath.Abs(path)
+	if err != nil {
+		panic(err)
+	}
+	return FsResource{
+		Path: absPath,
+	}
+}
+
+func(fs FsResource) GetTemplate(sym string) (string, error) {
+	fp := path.Join(fs.Path, sym)
+	r, err := ioutil.ReadFile(fp)
+	s := string(r)
+	return strings.TrimSpace(s), err
+}
+
+func(fs FsResource) GetCode(sym string) ([]byte, error) {
+	fb := sym + ".bin"
+	fp := path.Join(fs.Path, fb)
+	return ioutil.ReadFile(fp)
+}
+
+func(fs *FsResource) AddLocalFunc(sym string, fn EntryFunc) {
+	if fs.fns == nil {
+		fs.fns = make(map[string]EntryFunc)
+	}
+	fs.fns[sym] = fn
+}
+
+func(fs FsResource) FuncFor(sym string) (EntryFunc, error) {
+	fn, ok := fs.fns[sym]
+	if ok {
+		return fn, nil
+	}
+	_, err := fs.getFuncNoCtx(sym, nil)
+	if err != nil {
+		return nil, fmt.Errorf("unknown sym: %s", sym)
+	}
+	return fs.getFunc, nil
+}
+
+func(fs FsResource) String() string {
+	return fmt.Sprintf("fs resource at path: %s", fs.Path)
+}
+
+func(fs FsResource) getFunc(sym string, input []byte, ctx context.Context) (Result, error) {
+	return fs.getFuncNoCtx(sym, input)
+}
+
+func(fs FsResource) getFuncNoCtx(sym string, input []byte) (Result, error) {
+	fb := sym + ".txt"
+	fp := path.Join(fs.Path, fb)
+	log.Printf("getfunc search dir %s %s for %s", fs.Path, fp, sym)
+	r, err := ioutil.ReadFile(fp)
+	if err != nil {
+		return Result{}, fmt.Errorf("failed getting data for sym '%s': %v", sym, err)
+	}
+	s := string(r)
+	return Result{
+		Content: strings.TrimSpace(s),
+	}, nil
+}

resource/resource.go

@@ -0,0 +1,74 @@
+package resource
+
+import (
+	"context"
+)
+
+// Result contains the results of an external code operation.
+type Result struct {
+	Content string // content value for symbol after execution.
+	FlagSet []uint32 // request caller to set error flags at given indices.
+	FlagReset []uint32 // request caller to reset error flags at given indices.
+}
+
+// EntryFunc is a function signature for retrieving value for a key
+type EntryFunc func(sym string, input []byte, ctx context.Context) (Result, error)
+type CodeFunc func(sym string) ([]byte, error)
+type TemplateFunc func(sym string) (string, error)
+type FuncForFunc func(sym string) (EntryFunc, error)
+
+// Resource implementation are responsible for retrieving values and templates for symbols, and can render templates from value dictionaries.
+type Resource interface {
+	GetTemplate(sym string) (string, error) // Get the template for a given symbol.
+	GetCode(sym string) ([]byte, error) // Get the bytecode for the given symbol.
+	FuncFor(sym string) (EntryFunc, error) // Resolve symbol content point for.
+}
+
+// MenuResource contains the base definition for building Resource implementations.
+//
+// TODO: Rename to BaseResource
+type MenuResource struct {
+	sinkValues []string
+	codeFunc CodeFunc
+	templateFunc TemplateFunc
+	funcFunc FuncForFunc
+}
+
+// NewMenuResource creates a new MenuResource instance.
+func NewMenuResource() *MenuResource {
+	return &MenuResource{}
+}
+
+// WithCodeGetter sets the code symbol resolver method.
+func(m *MenuResource) WithCodeGetter(codeGetter CodeFunc) *MenuResource {
+	m.codeFunc = codeGetter
+	return m
+}
+
+// WithEntryGetter sets the content symbol resolver getter method.
+func(m *MenuResource) WithEntryFuncGetter(entryFuncGetter FuncForFunc) *MenuResource {
+	m.funcFunc = entryFuncGetter
+	return m
+}
+
+// WithTemplateGetter sets the template symbol resolver method.
+func(m *MenuResource) WithTemplateGetter(templateGetter TemplateFunc) *MenuResource {
+	m.templateFunc = templateGetter
+	return m
+}
+
+// FuncFor implements Resource interface
+func(m *MenuResource) FuncFor(sym string) (EntryFunc, error) {
+	return m.funcFunc(sym)
+}
+
+// GetCode implements Resource interface
+func(m *MenuResource) GetCode(sym string) ([]byte, error) {
+	return m.codeFunc(sym)
+}
+
+// GetTemplate implements Resource interface
+func(m *MenuResource) GetTemplate(sym string) (string, error) {
+	return m.templateFunc(sym)
+}
+

resource/resource_test.go

@@ -0,0 +1,63 @@
+package resource
+
+import (
+	"context"
+	"fmt"
+)
+
+
+type TestSizeResource struct {
+	*MenuResource
+}
+
+func getTemplate(sym string) (string, error) {
+	var tpl string
+	switch sym {
+	case "small":
+		tpl = "one {{.foo}} two {{.bar}} three {{.baz}}"
+	case "toobig":
+		tpl = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus in mattis lorem. Aliquam erat volutpat. Ut vitae metus."
+	case "pages":
+		tpl = "one {{.foo}} two {{.bar}} three {{.baz}}\n{{.xyzzy}}"
+	}
+	return tpl, nil
+}
+
+func funcFor(sym string) (EntryFunc, error) {
+	switch sym {
+	case "foo":
+		return get, nil
+	case "bar":
+		return get, nil
+	case "baz":
+		return get, nil
+	case "xyzzy":
+		return getXyzzy, nil
+	}
+	return nil, fmt.Errorf("unknown func: %s", sym)
+}
+
+func get(sym string, input []byte, ctx context.Context) (Result, error) {
+	switch sym {
+	case "foo":
+		return Result{
+			Content: "inky",
+		}, nil
+	case "bar":
+		return Result{
+			Content: "pinky",
+		}, nil
+	case "baz":
+		return Result{
+			Content: "blinky",
+		}, nil
+	}
+	return Result{}, fmt.Errorf("unknown sym: %s", sym)
+}
+
+func getXyzzy(sym string, input []byte, ctx context.Context) (Result, error) {
+	r := "inky pinky\nblinky clyde sue\ntinkywinky dipsy\nlala poo\none two three four five six seven\neight nine ten\neleven twelve"
+	return Result{
+		Content: r,
+	}, nil
+}

resource/state.go

@@ -0,0 +1,29 @@
+package resource
+
+import (
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+type StateResource struct {
+	Resource
+	st *state.State
+}
+
+func ToStateResource(rs Resource) *StateResource {
+	return &StateResource{rs, nil}
+}
+
+func NewStateResource(st *state.State) *StateResource {
+	return &StateResource{
+		NewMenuResource(),
+		st,
+	}
+}
+
+func (sr *StateResource) WithState(st *state.State) *StateResource {
+	if sr.st != nil {
+		panic("state already set")
+	}
+	sr.st = st
+	return sr
+}

resource/state_test.go

@@ -0,0 +1,14 @@
+package resource
+
+import (
+	"testing"
+
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+func TestStateResourceInit(t *testing.T) {
+	st := state.NewState(0)
+	rs := NewMenuResource()
+	_ = ToStateResource(rs).WithState(&st)
+	_ = NewStateResource(&st)
+}

state/flag.go

@@ -0,0 +1,24 @@
+package state
+
+const (
+	FLAG_READIN = iota
+	FLAG_INMATCH 
+	FLAG_TERMINATE 
+	FLAG_DIRTY
+	FLAG_WAIT
+	FLAG_LOADFAIL
+	FLAG_USERSTART = 8
+)
+
+func IsWriteableFlag(flag uint32) bool {
+	if flag > 7 {
+		return true
+	}
+	//if flag & FLAG_WRITEABLE > 0 {
+	//	return true	
+	//}
+	return false
+}
+
+type FlagDebugger struct {
+}

state/state.go

@@ -0,0 +1,352 @@
+package state
+
+import (
+	"fmt"
+	"log"
+	"strings"
+)
+
+type IndexError struct {
+}
+
+func(err *IndexError) Error() string {
+	return fmt.Sprintf("already at first index")
+}
+
+// State holds the command stack, error condition of a unique execution session.
+//
+// It also holds cached values for all results of executed symbols.
+//
+// Cached values are linked to the command stack level it which they were loaded. When they go out of scope they are freed.
+//
+// Values must be mapped to a level in order to be available for retrieval and count towards size
+//
+// It can hold a single argument, which is freed once it is read
+//
+// Symbols are loaded with individual size limitations. The limitations apply if a load symbol is updated. Symbols may be added with a 0-value for limits, called a "sink." If mapped, the sink will consume all net remaining size allowance unused by other symbols. Only one sink may be mapped per level.
+//
+// Symbol keys do not count towards cache size limitations.
+//
+// 8 first flags are reserved.
+type State struct {
+	Code []byte // Pending bytecode to execute
+	ExecPath []string // Command symbols stack
+	BitSize uint32 // size of (32-bit capacity) bit flag byte array
+	SizeIdx uint16
+	Flags []byte // Error state
+	Moves uint32 // Number of times navigation has been performed
+	input []byte // Last input
+}
+
+// number of bytes necessary to represent a bitfield of the given size.
+func toByteSize(BitSize uint32) uint8 {
+	if BitSize == 0 {
+		return 0
+	}
+	n := BitSize % 8
+	if n > 0 {
+		BitSize += (8 - n)
+	}
+	return uint8(BitSize / 8)
+}
+
+// Retrieve the state of a state flag
+func getFlag(bitIndex uint32, bitField []byte) bool {
+	byteIndex := bitIndex / 8
+	localBitIndex := bitIndex % 8
+	b := bitField[byteIndex]
+	return (b & (1 << localBitIndex)) > 0
+}
+
+// NewState creates a new State object with BitSize number of error condition states in ADDITION to the 8 builtin flags.
+func NewState(BitSize uint32) State {
+	st := State{
+		BitSize: BitSize + 8,
+	}
+	byteSize := toByteSize(BitSize + 8)
+	if byteSize > 0 {
+		st.Flags = make([]byte, byteSize) 
+	} else {
+		st.Flags = []byte{}
+	}
+	return st
+}
+
+// SetFlag sets the flag at the given bit field index
+//
+// Returns true if bit state was changed.
+//
+// Fails if bitindex is out of range.
+func(st *State) SetFlag(bitIndex uint32) (bool, error) {
+	if bitIndex + 1 > st.BitSize {
+		return false, fmt.Errorf("bit index %v is out of range of bitfield size %v", bitIndex, st.BitSize)
+	}
+	r := getFlag(bitIndex, st.Flags)
+	if r {
+		return false, nil
+	}
+	byteIndex := bitIndex / 8
+	localBitIndex := bitIndex % 8
+	b := st.Flags[byteIndex] 
+	st.Flags[byteIndex] = b | (1 << localBitIndex)
+	return true, nil
+}
+
+
+// ResetFlag resets the flag at the given bit field index.
+//
+// Returns true if bit state was changed.
+//
+// Fails if bitindex is out of range.
+func(st *State) ResetFlag(bitIndex uint32) (bool, error) {
+	if bitIndex + 1 > st.BitSize {
+		return false, fmt.Errorf("bit index %v is out of range of bitfield size %v", bitIndex, st.BitSize)
+	}
+	r := getFlag(bitIndex, st.Flags)
+	if !r {
+		return false, nil
+	}
+	byteIndex := bitIndex / 8
+	localBitIndex := bitIndex % 8
+	b := st.Flags[byteIndex] 
+	st.Flags[byteIndex] = b & (^(1 << localBitIndex))
+	return true, nil
+}
+
+// GetFlag returns the state of the flag at the given bit field index.
+//
+// Fails if bit field index is out of range.
+func(st *State) GetFlag(bitIndex uint32) (bool, error) {
+	if bitIndex + 1 > st.BitSize {
+		return false, fmt.Errorf("bit index %v is out of range of bitfield size %v", bitIndex, st.BitSize)
+	}
+	return getFlag(bitIndex, st.Flags), nil
+}
+
+// FlagBitSize reports the amount of bits available in the bit field index.
+func(st *State) FlagBitSize() uint32 {
+	return st.BitSize
+}
+
+// FlagBitSize reports the amount of bits available in the bit field index.
+func(st *State) FlagByteSize() uint8 {
+	return uint8(len(st.Flags))
+}
+
+// MatchFlag matches the current state of the given flag.
+//
+// The flag is specified given its bit index in the bit field.
+//
+// If invertMatch is set, a positive result will be returned if the flag is not set.
+func(st *State) MatchFlag(sig uint32, invertMatch bool) (bool, error) {
+	r, err := st.GetFlag(sig)
+	if err != nil {
+		return false, err
+	}
+	if invertMatch {
+		if !r {
+			return true, nil
+		}
+	} else if r {
+		return true, nil
+	}
+	return false, nil
+}
+
+// GetIndex scans a byte slice in same order as in storage, and returns the index of the first set bit.
+//
+// If the given byte slice is too small for the bit field bitsize, the check will terminate at end-of-data without error.
+func(st *State) GetIndex(flags []byte) bool {
+	var globalIndex uint32
+	if st.BitSize == 0 {
+		return false
+	}
+	if len(flags) == 0 {
+		return false
+	}
+	var byteIndex uint8
+	var localIndex uint8
+	l := uint8(len(flags))
+	var i uint32
+	for i = 0; i < st.BitSize; i++ {
+		testVal := flags[byteIndex] & (1 << localIndex)
+		if (testVal & st.Flags[byteIndex]) > 0 {
+			return true
+		}
+		globalIndex += 1
+		if globalIndex % 8 == 0 {
+			byteIndex += 1
+			localIndex = 0
+			if byteIndex > (l - 1) {
+				return false				
+			}
+		} else {
+			localIndex += 1
+		}
+	}
+	return false
+}
+
+// Where returns the current active rendering symbol.
+func(st *State) Where() (string, uint16) {
+	if len(st.ExecPath) == 0 {
+		return "", 0
+	}
+	l := len(st.ExecPath)
+	return st.ExecPath[l-1], st.SizeIdx
+}
+
+// Next moves to the next sink page index.
+func(st *State) Next() (uint16, error) {
+	if len(st.ExecPath) == 0 {
+		return 0, fmt.Errorf("state root node not yet defined")
+	}
+	st.SizeIdx += 1
+	s, idx := st.Where()
+	log.Printf("next page for %s: %v", s, idx)
+	st.Moves += 1
+	return st.SizeIdx, nil
+}
+
+func(st *State) Same() {
+	st.Moves += 1
+}
+
+// Previous moves to the next sink page index.
+//
+// Fails if try to move beyond index 0.
+func(st *State) Previous() (uint16, error) {
+	if len(st.ExecPath) == 0 {
+		return 0, fmt.Errorf("state root node not yet defined")
+	}
+	if st.SizeIdx == 0 {
+		return 0, &IndexError{} // ("already at first index")
+	}
+	st.SizeIdx -= 1
+	s, idx := st.Where()
+	log.Printf("previous page for %s: %v", s, idx)
+	st.Moves += 1
+	return st.SizeIdx, nil
+}
+
+// Sides informs the caller which index page options will currently succeed.
+//
+// Two values are returned, for the "next" and "previous" options in that order. A false value means the option is not available in the current state.
+func(st *State) Sides() (bool, bool) {
+	if len(st.ExecPath) == 0 {
+		return false, false
+	}
+	next := true
+	log.Printf("sides %v", st.SizeIdx)
+	if st.SizeIdx == 0 {
+		return next, false	
+	}
+	return next, true
+}
+
+// Top returns true if currently at topmode node.
+//
+// Fails if first Down() was never called.
+func(st *State) Top() (bool, error) {
+	if len(st.ExecPath) == 0 {
+		return false, fmt.Errorf("state root node not yet defined")
+	}
+	return len(st.ExecPath) == 1, nil
+}
+
+// Down adds the given symbol to the command stack.
+//
+// Clears mapping and sink.
+func(st *State) Down(input string) error {
+	st.ExecPath = append(st.ExecPath, input)
+	st.SizeIdx = 0
+	st.Moves += 1
+	return nil
+}
+
+// Up removes the latest symbol to the command stack, and make the previous symbol current.
+//
+// Frees all symbols and associated values loaded at the previous stack level. Cache capacity is increased by the corresponding amount.
+//
+// Clears mapping and sink.
+//
+// Fails if called at top frame.
+func(st *State) Up() (string, error) {
+	l := len(st.ExecPath)
+	if l == 0 {
+		return "", fmt.Errorf("exit called beyond top frame")
+	}
+	log.Printf("execpath before %v", st.ExecPath)
+	st.ExecPath = st.ExecPath[:l-1]
+	sym := ""
+	if len(st.ExecPath) > 0 {
+		sym = st.ExecPath[len(st.ExecPath)-1]
+	}
+	st.SizeIdx = 0
+	log.Printf("execpath after %v", st.ExecPath)
+	st.Moves += 1
+	return sym, nil
+}
+
+// Depth returns the current call stack depth.
+func(st *State) Depth() uint8 {
+	return uint8(len(st.ExecPath)-1)
+}
+
+// Appendcode adds the given bytecode to the end of the existing code.
+func(st *State) AppendCode(b []byte) error {
+	st.Code = append(st.Code, b...)
+	log.Printf("code changed to 0x%x", b)
+	return nil
+}
+
+// SetCode replaces the current bytecode with the given bytecode.
+func(st *State) SetCode(b []byte) {
+	log.Printf("code set to 0x%x", b)
+	st.Code = b
+}
+
+// Get the remaning cached bytecode
+func(st *State) GetCode() ([]byte, error) {
+	b := st.Code
+	st.Code = []byte{}
+	return b, nil
+}
+
+// GetInput gets the most recent client input.
+func(st *State) GetInput() ([]byte, error) {
+	if st.input == nil {
+		return nil, fmt.Errorf("no input has been set")
+	}
+	return st.input, nil
+}
+
+// SetInput is used to record the latest client input.
+func(st *State) SetInput(input []byte) error {
+	l := len(input)
+	if l > 255 {
+		return fmt.Errorf("input size %v too large (limit %v)", l, 255)
+	}
+	st.input = input
+	return nil
+}
+
+// Reset re-initializes the state to run from top node with accumulated client state.
+func(st *State) Restart() error {
+	st.resetBaseFlags()
+	st.Moves = 0
+	st.SizeIdx = 0
+	st.input = []byte{}
+	return nil
+}
+
+// String implements String interface
+func(st State) String() string {
+	return fmt.Sprintf("moves %v idx %v flags: 0x%x path: %s", st.Moves, st.SizeIdx, st.Flags, strings.Join(st.ExecPath, "/"))
+}
+
+// initializes all flags not in control of client.
+func(st *State) resetBaseFlags() {
+	st.Flags[0] = 0
+}
+

state/state_test.go

@@ -0,0 +1,219 @@
+package state
+
+import (
+	"bytes"
+	"testing"
+)
+
+// Check creation 
+func TestNewState(t *testing.T) {
+	st := NewState(5)
+	if len(st.Flags) != 2 {
+		t.Fatalf("invalid state flag length: %v", len(st.Flags))
+	}
+	st = NewState(8)
+	if len(st.Flags) != 2 {
+		t.Fatalf("invalid state flag length: %v", len(st.Flags))
+	}
+	st = NewState(17)
+	if len(st.Flags) != 4 {
+		t.Fatalf("invalid state flag length: %v", len(st.Flags))
+	}
+}
+
+func TestStateflags(t *testing.T) {
+	st := NewState(9)
+	v, err := st.GetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	if v {
+		t.Fatalf("Expected bit 2 not to be set")
+	}
+	v, err = st.SetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Fatalf("Expected change to be set for bit 2")
+	}
+	v, err = st.GetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Fatalf("Expected bit 2 to be set")
+	}
+	v, err = st.SetFlag(10)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Fatalf("Expected change to be set for bit 10")
+	}
+	v, err = st.GetFlag(10)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Fatalf("Expected bit 10 to be set")
+	}
+	v, err = st.ResetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Fatalf("Expected change to be set for bit 10")
+	}
+	v, err = st.GetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	if v {
+		t.Fatalf("Expected bit 2 not to be set")
+	}
+	v, err = st.GetFlag(10)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Fatalf("Expected bit 10 to be set")
+	}
+	v, err = st.SetFlag(10)
+	if err != nil {
+		t.Error(err)
+	}
+	if v {
+		t.Fatalf("Expected change not to be set for bit 10")
+	}
+	v, err = st.SetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	v, err = st.SetFlag(16)
+	if err != nil {
+		t.Error(err)
+	}
+	v, err = st.SetFlag(17)
+	if err == nil {
+		t.Fatalf("Expected out of range for bit index 17")
+	}
+	if !bytes.Equal(st.Flags[:3], []byte{0x04, 0x04, 0x01}) {
+		t.Fatalf("Expected 0x040401, got %v", st.Flags[:3])
+	}
+}
+
+func TestStateFlagFromSlice(t *testing.T) {
+	st := NewState(15)
+	_, _= st.SetFlag(2)
+	v := st.GetIndex([]byte{})
+	if v {
+		t.Fatalf("Expected no match on empty compare")
+	}
+	v = st.GetIndex([]byte{0x01})
+	if v {
+		t.Fatalf("Expected 0x01 not to match")
+	}
+	v = st.GetIndex([]byte{0x04})
+	if !v {
+		t.Fatalf("Expected 0x04 to match")
+	}
+	_, _= st.SetFlag(12)
+	v = st.GetIndex([]byte{0x04})
+	if !v {
+		t.Fatalf("Expected 0x04 to match")
+	}
+	v = st.GetIndex([]byte{0x00, 0x10})
+	if !v {
+		t.Fatalf("Expected 0x1000 to match")
+	}
+	v, _ = st.ResetFlag(2)
+	v = st.GetIndex([]byte{0x00, 0x10})
+	if !v {
+		t.Fatalf("Expected 0x1000 to matck")
+	}
+}
+
+func TestStateNavigate(t *testing.T) {
+	st := NewState(0)
+	err := st.Down("foo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = st.Down("bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = st.Down("baz")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s, i := st.Where()
+	if s != "baz" {
+		t.Fatalf("expected baz, got %s", s)
+	}
+	if i != 0 {
+		t.Fatalf("expected idx 0, got %v", i)
+	}
+	r := st.Depth()
+	if r != 2 {
+		t.Fatalf("expected depth 3, got %v", r)
+	}
+
+	s, err = st.Up()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if s != "bar" {
+		t.Fatalf("expected bar, got %s", s)
+	}
+	s, i = st.Where()
+	if s != "bar" {
+		t.Fatalf("expected bar, got %s", s)
+	}
+	if i != 0 {
+		t.Fatalf("expected idx 0, got %v", i)
+	}
+
+	i, err = st.Next()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if i != 1 {
+		t.Fatalf("expected idx 1, got %v", i)
+	}
+	i, err = st.Next()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if i != 2 {
+		t.Fatalf("expected idx 2, got %v", i)
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s, i = st.Where()
+	if s != "bar" {
+		t.Fatalf("expected baz, got %s", s)
+	}
+	if i != 2 {
+		t.Fatalf("expected idx 2, got %v", i)
+	}
+
+	s, err = st.Up()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if s != "foo" {
+		t.Fatalf("expected foo, got %s", s)
+	}
+	s, i = st.Where()
+	if s != "foo" {
+		t.Fatalf("expected foo, got %s", s)
+	}
+	if i != 0 {
+		t.Fatalf("expected idx 0, got %v", i)
+	}
+}

testdata/testdata.go

@@ -0,0 +1,192 @@
+package testdata
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+
+	testdataloader "github.com/peteole/testdata-loader"
+
+	"git.grassecon.net/kamikazechaser/vise/vm"
+)
+
+type genFunc func() error
+
+var (
+	BaseDir = testdataloader.GetBasePath()
+	DataDir = ""
+	dirLock = false
+)
+
+func out(sym string, b []byte, tpl string, data map[string]string) error {
+	fp := path.Join(DataDir, sym)
+	err := ioutil.WriteFile(fp, []byte(tpl), 0644)
+	if err != nil {
+		return err
+	}
+
+	fb := sym + ".bin"
+	fp = path.Join(DataDir, fb)
+	err = ioutil.WriteFile(fp, b, 0644)
+	if err != nil {
+		return err
+	}
+
+	if data == nil {
+		return nil
+	}
+
+	for k, v := range data {
+		fb := k + ".txt"
+		fp = path.Join(DataDir, fb)
+		err = ioutil.WriteFile(fp, []byte(v), 0644)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func root() error {
+	b := []byte{}
+	b = vm.NewLine(b, vm.MOUT, []string{"1", "do the foo"}, nil, nil)
+	b = vm.NewLine(b, vm.MOUT, []string{"2", "go to the bar"}, nil, nil)
+	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
+	b = vm.NewLine(b, vm.INCMP, []string{"1", "foo"}, nil, nil)
+	b = vm.NewLine(b, vm.INCMP, []string{"2", "bar"}, nil, nil)
+
+	tpl := "hello world"
+
+	return out("root", b, tpl, nil)
+}
+
+func foo() error {
+	b := []byte{}
+	b = vm.NewLine(b, vm.MOUT, []string{"0", "to foo"}, nil, nil)
+	b = vm.NewLine(b, vm.MOUT, []string{"1", "go bar"}, nil, nil)
+	b = vm.NewLine(b, vm.MOUT, []string{"2", "see long"}, nil, nil)
+	b = vm.NewLine(b, vm.LOAD, []string{"inky"}, []byte{20}, nil)
+	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
+	b = vm.NewLine(b, vm.INCMP, []string{"0", "_"}, nil, nil)
+	b = vm.NewLine(b, vm.INCMP, []string{"1", "baz"}, nil, nil)
+	b = vm.NewLine(b, vm.INCMP, []string{"2", "long"}, nil, nil)
+
+	data := make(map[string]string)
+	data["inky"] = "one"
+
+	tpl := `this is in foo
+
+it has more lines`
+
+	return out("foo", b, tpl, data)
+}
+
+func bar() error {
+	b := []byte{}
+	b = vm.NewLine(b, vm.LOAD, []string{"pinky"}, []byte{0}, nil)
+	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
+	b = vm.NewLine(b, vm.INCMP, []string{"*", "^"}, nil, nil)
+
+	tpl := "this is bar - any input will return to top"
+
+	data := make(map[string]string)
+	data["pinky"] = "two"
+
+	return out("bar", b, tpl, data)
+}
+
+func baz() error {
+	b := []byte{}
+	b = vm.NewLine(b, vm.MAP, []string{"inky"}, nil, nil)
+	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
+
+	tpl := "this is baz which uses the var {{.inky}} in the template."
+
+	return out("baz", b, tpl, nil)
+}
+
+func long() error {
+	b := []byte{}
+	b = vm.NewLine(b, vm.MOUT, []string{"0", "back"}, nil, nil)
+	b = vm.NewLine(b, vm.MNEXT, []string{"00", "nexxt"}, nil, nil)
+	b = vm.NewLine(b, vm.MPREV, []string{"11", "prevvv"}, nil, nil)
+	b = vm.NewLine(b, vm.LOAD, []string{"longdata"}, []byte{0x00}, nil)
+	b = vm.NewLine(b, vm.MAP, []string{"longdata"}, nil, nil)
+	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
+	b = vm.NewLine(b, vm.INCMP, []string{"0", "_"}, nil, nil)
+	b = vm.NewLine(b, vm.INCMP, []string{"00", ">"}, nil, nil)
+	b = vm.NewLine(b, vm.INCMP, []string{"11", "<"}, nil, nil)
+
+	tpl := `data
+{{.longdata}}`
+
+	data := make(map[string]string)
+	data["longdata"] = `INKY 12
+PINKY 5555
+BLINKY 3t7
+CLYDE 11
+TINKYWINKY 22
+DIPSY 666
+LALA 111
+POO 222
+`
+
+	return out("long", b, tpl, data)
+}
+
+func defaultCatch() error {
+	b := []byte{}
+	b = vm.NewLine(b, vm.MOUT, []string{"0", "back"}, nil, nil)
+	b = vm.NewLine(b, vm.HALT, nil, nil, nil)
+	b = vm.NewLine(b, vm.INCMP, []string{"*", "_"}, nil, nil)
+
+	tpl := "invalid input"
+
+	return out("_catch", b, tpl, nil)
+}
+
+func generate() error {
+	err := os.MkdirAll(DataDir, 0755)
+	if err != nil {
+		return err
+	}
+
+	fns := []genFunc{root, foo, bar, baz, long, defaultCatch}
+	for _, fn := range fns {
+		err = fn()
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Generate outputs bytecode, templates and content symbols to a temporary directory.
+//
+// This directory can in turn be used as data source for the the resource.FsResource object.
+func Generate() (string, error) {
+	dir, err := ioutil.TempDir("", "vise_testdata_")
+	if err != nil {
+		return "", err
+	}
+	DataDir = dir
+	dirLock = true
+	err = generate()
+	return dir, err
+}
+
+// Generate outputs bytecode, templates and content symbols to a specified directory.
+//
+// The directory must exist, and must not have been used already in the same code execution.
+//
+// This directory can in turn be used as data source for the the resource.FsResource object.
+func GenerateTo(dir string) error {
+	if dirLock {
+		return fmt.Errorf("directory already overridden")
+	}
+	DataDir = dir
+	dirLock = true
+	return generate()
+}

vm/doc.go

@@ -0,0 +1,2 @@
+// Package vm handles the line-by-line execution of vise bytecode.
+package vm

vm/input.go

@@ -0,0 +1,156 @@
+package vm
+
+import (
+	"context"
+	"fmt"
+	"regexp"
+
+	"git.grassecon.net/kamikazechaser/vise/cache"
+	"git.grassecon.net/kamikazechaser/vise/state"
+)
+
+var (
+	inputRegexStr = "^[a-zA-Z0-9].*$"
+	inputRegex    = regexp.MustCompile(inputRegexStr)
+	ctrlRegexStr  = "^[><_^.]$"
+	ctrlRegex     = regexp.MustCompile(ctrlRegexStr)
+	symRegexStr   = "^[a-zA-Z0-9][a-zA-Z0-9_]+$"
+	symRegex      = regexp.MustCompile(symRegexStr)
+)
+
+// CheckInput validates the given byte string as client input.
+func ValidInput(input []byte) error {
+	if !inputRegex.Match(input) {
+		return fmt.Errorf("Input '%s' does not match input format /%s/", input, inputRegexStr)
+	}
+	return nil
+}
+
+// control characters for relative navigation.
+func validControl(input []byte) error {
+	if !ctrlRegex.Match(input) {
+		return fmt.Errorf("Input '%s' does not match 'control' format /%s/", input, ctrlRegexStr)
+	}
+	return nil
+}
+
+// CheckSym validates the given byte string as a node symbol.
+func ValidSym(input []byte) error {
+	if !symRegex.Match(input) {
+		return fmt.Errorf("Input '%s' does not match 'sym' format /%s/", input, symRegexStr)
+	}
+	return nil
+}
+
+// false if target is not valid
+func valid(target []byte) bool {
+	var ok bool
+	if len(target) == 0 {
+		return false
+	}
+
+	err := ValidSym(target)
+	if err == nil {
+		ok = true
+	}
+
+	if !ok {
+		err = validControl(target)
+		if err == nil {
+			ok = true
+		}
+	}
+	return ok
+}
+
+// CheckTarget tests whether the navigation state transition is available in the current state.
+//
+// Fails if target is formally invalid, or if navigation is unavailable.
+func CheckTarget(target []byte, st *state.State) (bool, error) {
+	ok := valid(target)
+	if !ok {
+		return false, fmt.Errorf("invalid target: %x", target)
+	}
+
+	switch target[0] {
+	case '_':
+		topOk, err := st.Top()
+		if err != nil {
+			return false, err
+		}
+		return topOk, nil
+	case '<':
+		_, prevOk := st.Sides()
+		return prevOk, nil
+	case '>':
+		nextOk, _ := st.Sides()
+		return nextOk, nil
+	}
+	return true, nil
+}
+
+// route parsed target symbol to navigation state change method,
+func applyTarget(target []byte, st *state.State, ca cache.Memory, ctx context.Context) (string, uint16, error) {
+	var err error
+	sym, idx := st.Where()
+
+	ok := valid(target)
+	if !ok {
+		return sym, idx, fmt.Errorf("invalid input: %x", target)
+	}
+
+	switch target[0] {
+	case '_':
+		sym, err = st.Up()
+		if err != nil {
+			return sym, idx, err
+		}
+		err = ca.Pop()
+		if err != nil {
+			return sym, idx, err
+		}
+
+	case '>':
+		idx, err = st.Next()
+		if err != nil {
+			return sym, idx, err
+		}
+	case '<':
+		idx, err = st.Previous()
+		if err != nil {
+			return sym, idx, err
+		}
+	case '^':
+		notTop := true
+		for notTop {
+			notTop, err := st.Top()
+			if notTop {
+				break
+			}
+			sym, err = st.Up()
+			if err != nil {
+				return sym, idx, err
+			}
+			err = ca.Pop()
+			if err != nil {
+				return sym, idx, err
+			}
+		}
+	case '.':
+		st.Same()
+		location, idx := st.Where()
+		return location, idx, nil
+	default:
+		sym = string(target)
+		err := st.Down(sym)
+		if err != nil {
+			return sym, idx, err
+		}
+		err = ca.Push()
+		if err != nil {
+			return sym, idx, err
+		}
+		idx = 0
+	}
+	return sym, idx, nil
+}