draw2d/postscript/interpreter.go

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// Copyright 2010 The postscript-go Authors. All rights reserved.
// created: 13/12/2010 by Laurent Le Goff
package postscript
import (
"os"
"log"
"strconv"
"io"
"draw2d.googlecode.com/hg/draw2d"
)
type Interpreter struct {
valueStack ValueStack
dictionaryStack DictionaryStack
gc draw2d.GraphicContext
}
type Value interface{}
type ValueStack []Value
type Dictionary map[string]Value
type DictionaryStack []Dictionary
type Operator interface {
Execute(interpreter *Interpreter)
}
func NewInterpreter(gc draw2d.GraphicContext) *Interpreter {
interpreter := new(Interpreter)
interpreter.valueStack = make([]Value, 0, 100)
interpreter.dictionaryStack = make([]Dictionary, 2, 10)
interpreter.dictionaryStack[0] = NewDictionary(100) // System dictionary
interpreter.dictionaryStack[1] = NewDictionary(100) // user dictionary
initSystemOperators(interpreter)
interpreter.gc = gc
return interpreter
}
func NewDictionary(prealloc int) Dictionary {
return make(Dictionary, prealloc)
}
func (interpreter *Interpreter) GetGraphicContext() draw2d.GraphicContext {
return interpreter.gc
}
func (interpreter *Interpreter) Execute(reader io.Reader) {
var scanner Scanner
scanner.Init(reader)
token := scanner.Scan()
for token != EOF {
interpreter.scan(&scanner, token)
token = scanner.Scan()
}
}
func (interpreter *Interpreter) ExecuteFile(filePath string) os.Error {
src, err := os.Open(filePath)
if src == nil {
log.Printf("can't open file; err=%s\n", err.String())
return err
}
defer src.Close()
interpreter.Execute(src)
return nil
}
func (interpreter *Interpreter) computeReference(ref string) {
value, _ := interpreter.FindValueInDictionaries(ref)
if value == nil {
log.Printf("Unknown def: %s\n", ref)
} else {
operator, isOperator := value.(Operator)
if isOperator {
operator.Execute(interpreter)
} else {
interpreter.Push(value)
}
}
}
func (interpreter *Interpreter) scan(scanner *Scanner, token int) {
if token == Ident {
switch scanner.TokenText() {
case "true":
interpreter.Push(true)
case "false":
interpreter.Push(false)
case "null":
interpreter.Push(nil)
default:
interpreter.computeReference(scanner.TokenText())
}
} else if token == '/' {
scanner.Scan()
interpreter.Push("/" + scanner.TokenText())
} else if token == '[' {
interpreter.Push(interpreter.scanArray(scanner))
} else if token == '{' {
// procedure
interpreter.Push(interpreter.scanProcedure(scanner))
} else if token == Float || token == Int {
f, err := strconv.Atof64(scanner.TokenText())
if err != nil {
log.Printf("Float expected: %s\n", scanner.TokenText())
interpreter.Push(scanner.TokenText())
} else {
interpreter.Push(f)
}
} else {
interpreter.Push(scanner.TokenText())
}
}
func (interpreter *Interpreter) scanArray(scanner *Scanner) []Value {
array := make([]Value, 0, 10)
token := scanner.Scan()
for token != EOF && token != ']' {
if token == Ident {
var v Value = scanner.TokenText()
switch scanner.TokenText() {
case "true":
v = true
case "false":
v = false
case "null":
v = nil
}
array = append(array, v)
} else {
interpreter.scan(scanner, token)
array = append(array, interpreter.Pop())
}
token = scanner.Scan()
}
return array
}
func (interpreter *Interpreter) scanProcedure(scanner *Scanner) *ProcedureDefinition {
proceduredef := NewProcedureDefinition()
token := scanner.Scan()
for token != EOF && token != '}' {
if token == Ident {
var v Value = scanner.TokenText()
switch scanner.TokenText() {
case "true":
v = true
case "false":
v = false
case "null":
v = nil
}
proceduredef.Add(v)
} else {
interpreter.scan(scanner, token)
proceduredef.Add(interpreter.Pop())
}
token = scanner.Scan()
}
return proceduredef
}
//Dictionary Operation
func (interpreter *Interpreter) PushDictionary(dictionary Dictionary) {
interpreter.dictionaryStack = append(interpreter.dictionaryStack, dictionary)
}
func (interpreter *Interpreter) PopDictionary() Dictionary {
stackPointer := len(interpreter.dictionaryStack) - 1
dictionary := interpreter.dictionaryStack[stackPointer]
interpreter.dictionaryStack = interpreter.dictionaryStack[0:stackPointer]
return dictionary
}
func (interpreter *Interpreter) PeekDictionary() Dictionary {
stackPointer := len(interpreter.dictionaryStack) - 1
return interpreter.dictionaryStack[stackPointer]
}
func (interpreter *Interpreter) ClearDictionaries() {
interpreter.dictionaryStack = interpreter.dictionaryStack[:2]
}
func (interpreter *Interpreter) DictionaryStackSize() int {
return len(interpreter.dictionaryStack)
}
func (interpreter *Interpreter) FindValue(name string) Value {
return interpreter.PeekDictionary()[name]
}
func (interpreter *Interpreter) FindValueInDictionaries(name string) (Value, Dictionary) {
for i := len(interpreter.dictionaryStack) - 1; i >= 0; i-- {
value := interpreter.dictionaryStack[i][name]
if value != nil {
return value, interpreter.dictionaryStack[i]
}
}
return nil, nil
}
func (interpreter *Interpreter) UserDictionary() Dictionary {
return interpreter.dictionaryStack[0]
}
func (interpreter *Interpreter) SystemDictionary() Dictionary {
return interpreter.dictionaryStack[0]
}
func (interpreter *Interpreter) Define(name string, value Value) {
interpreter.PeekDictionary()[name] = value
}
func (interpreter *Interpreter) SystemDefine(name string, value Value) {
interpreter.dictionaryStack[0][name] = value
}
//Operand Operation
func (interpreter *Interpreter) Push(operand Value) {
//log.Printf("Push operand: %v\n", operand)
interpreter.valueStack = append(interpreter.valueStack, operand)
}
func (interpreter *Interpreter) Pop() Value {
valueStackPointer := len(interpreter.valueStack) - 1
operand := interpreter.valueStack[valueStackPointer]
interpreter.valueStack = interpreter.valueStack[0:valueStackPointer]
//log.Printf("Pop operand: %v\n", operand)
return operand
}
func (interpreter *Interpreter) PopValues(n int) []Value {
valueStackPointer := len(interpreter.valueStack) - 1
operands := make([]Value, n)
copy(operands, interpreter.valueStack[valueStackPointer-n+1:valueStackPointer+1])
interpreter.valueStack = interpreter.valueStack[0 : valueStackPointer-n+1]
return operands
}
func (interpreter *Interpreter) GetValues(n int) []Value {
valueStackPointer := len(interpreter.valueStack) - 1
operands := make([]Value, n)
copy(operands, interpreter.valueStack[valueStackPointer-n+1:valueStackPointer+1])
return operands
}
func (interpreter *Interpreter) Get(index int) Value {
valueStackPointer := len(interpreter.valueStack) - 1
return interpreter.valueStack[valueStackPointer-index]
}
func (interpreter *Interpreter) Peek() Value {
valueStackPointer := len(interpreter.valueStack) - 1
return interpreter.valueStack[valueStackPointer]
}
func (interpreter *Interpreter) OperandSize() int {
return len(interpreter.valueStack)
}
func (interpreter *Interpreter) ClearOperands() {
interpreter.valueStack = interpreter.valueStack[0:0]
}
// misc pop
func (interpreter *Interpreter) PopFloat() float64 {
operand := interpreter.Pop()
return operand.(float64)
}
func (interpreter *Interpreter) PopInt() int {
f := interpreter.PopFloat()
return int(f)
}
func (interpreter *Interpreter) PopOperator() Operator {
operator := interpreter.Pop()
return operator.(Operator)
}
func (interpreter *Interpreter) PopProcedureDefinition() *ProcedureDefinition {
def := interpreter.Pop()
return def.(*ProcedureDefinition)
}
func (interpreter *Interpreter) PopName() string {
name := interpreter.Pop().(string)
return name[1:]
}
func (interpreter *Interpreter) PopString() string {
s := interpreter.Pop().(string)
return s[1 : len(s)-1]
}
func (interpreter *Interpreter) PopBoolean() bool {
s := interpreter.Pop()
return s.(bool)
}
func (interpreter *Interpreter) PopArray() []Value {
s := interpreter.Pop()
return s.([]Value)
}