Add interactive runner

README.md

@@ -5,6 +5,7 @@ An attempt at defining a small VM to handle menu interaction for size-constraine
 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.
 
 
+
 ## Opcodes
 
 The VM defines the following opcode symbols:
@@ -138,7 +139,32 @@ It expects all replacement symbols to be available at time of rendering, and has
 0007                       # HALT              - stop execution
 ```
 
-## Assembly language
+## Development tools
+
+Located in the `dev/` directory.
+
+
+### Test data generation
+
+`go run ./dev/testdata/ <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>]`
+
+Creates a new interactive session using `engine.DefaultEngine`, starting execution at symbol `root_symbol`
+
+`data_directory` points to a directory where templates and bytecode is to be found (in the same format as generated by `dev/testdata`).
+
+If `data_directory` is not set, current directory will be used.
+
+if `root_symbol` is not set, the symbol `root` will be used.
+
+
+### Assembler
 
 **TBD**
 

go/dev/interactive.go

@@ -22,7 +22,7 @@ func main() {
 
 	ctx := context.Background()
 	en := engine.NewDefaultEngine(dir)
-	err := en.Init("root", ctx)
+	err := en.Init(root, ctx)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "cannot init: %v\n", err)
 		os.Exit(1)
@@ -33,13 +33,13 @@ func main() {
 		reader := bufio.NewReader(os.Stdin)
 		in, err := reader.ReadString('\n')
 		if err != nil {
-			fmt.Fprintf(os.Stderr, "cannot read input: %v", err)
+			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", err)
+			fmt.Fprintf(os.Stderr, "execution terminated: %v\n", err)
 			os.Exit(1)
 		}
 		b := bytes.NewBuffer(nil)