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