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Switch to two arrays for instructions.

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This commit is contained in:
Brendan Dahl 2011-12-28 20:08:18 -08:00
parent 971f35d165
commit 27b0d0c941
2 changed files with 48 additions and 37 deletions
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65
src/function.js
View File

@ -360,7 +360,7 @@ var PDFFunction = (function PDFFunctionClosure() {
var range = IR[2];
var code = IR[3];
var numOutputs = range.length / 2;
var evaluator = new PostScriptEvaluator(code);
var evaluator = new PostScriptEvaluator(code[0], code[1]);
// Cache the values for a big speed up, the cache size is limited though
// since the number of possible values can be huge from a PS function.
var cache = new FunctionCache();
@ -455,31 +455,36 @@ var PostScriptStack = (function PostScriptStack() {
return PostScriptStack;
})();
var PostScriptEvaluator = (function PostScriptEvaluator() {
function PostScriptEvaluator(code) {
this.code = code;
console.log(code);
function PostScriptEvaluator(operators, operands) {
this.operators = operators;
this.operands = operands;
}
PostScriptEvaluator.prototype = {
execute: function(initialStack) {
var stack = new PostScriptStack(initialStack);
var counter = 0;
var code = this.code;
var a, b;
while (counter < this.code.length) {
var instruction = this.code[counter++];
var operator = instruction[0];
var operators = this.operators;
var operands = this.operands;
var length = operators.length;
var a, b, operand;
while (counter < length) {
var operator = operators[counter];
++counter;
switch (operator) {
// non standard ps operators
case 'push':
stack.push(instruction[1]);
operand = operands[counter - 1];
stack.push(operand);
break;
case 'jz': // jump if false
operand = operands[counter - 1];
a = stack.pop();
if (!a)
counter = instruction[1];
counter = operand;
break;
case 'j': // jump
counter = instruction[1];
operand = operands[counter - 1];
counter = operand;
break;
// all ps operators in alphabetical order (excluding if/ifelse)
@ -690,7 +695,8 @@ var PostScriptEvaluator = (function PostScriptEvaluator() {
var PostScriptParser = (function PostScriptParser() {
function PostScriptParser(lexer) {
this.lexer = lexer;
this.code = [];
this.operators = [];
this.operands = [];
this.token;
this.prev;
}
@ -717,14 +723,16 @@ var PostScriptParser = (function PostScriptParser() {
this.expect(PostScriptTokenTypes.LBRACE);
this.parseBlock();
this.expect(PostScriptTokenTypes.RBRACE);
return this.code;
return [this.operators, this.operands];
},
parseBlock: function parseBlock() {
while (true) {
if (this.accept(PostScriptTokenTypes.NUMBER)) {
this.code.push(['push', this.prev.value]);
this.operators.push('push');
this.operands.push(this.prev.value);
} else if (this.accept(PostScriptTokenTypes.OPERATOR)) {
this.code.push([this.prev.value]);
this.operators.push(this.prev.value);
this.operands.push(null);
} else if (this.accept(PostScriptTokenTypes.LBRACE)) {
this.parseCondition();
} else {
@ -733,26 +741,33 @@ var PostScriptParser = (function PostScriptParser() {
}
},
parseCondition: function parseCondition() {
var counter = this.code.length - 1;
var condition = [];
this.code.push(condition);
// Add two place holders that will be updated later
var conditionLocation = this.operators.length;
this.operators.push(null);
this.operands.push(null);
this.parseBlock();
this.expect(PostScriptTokenTypes.RBRACE);
if (this.accept(PostScriptTokenTypes.IF)) {
// The true block is right after the 'if' so it just falls through on
// true else it jumps and skips the true block.
condition.push('jz', this.code.length);
this.operators[conditionLocation] = 'jz';
this.operands[conditionLocation] = this.operators.length;
} else if (this.accept(PostScriptTokenTypes.LBRACE)) {
var jump = [];
this.code.push(jump);
var endOfTrue = this.code.length;
var jumpLocation = this.operators.length;
this.operators.push(null);
this.operands.push(null);
var endOfTrue = this.operators.length;
this.parseBlock();
this.expect(PostScriptTokenTypes.RBRACE);
this.expect(PostScriptTokenTypes.IFELSE);
// The jump is added at the end of the true block to skip the false
// block.
jump.push('j', this.code.length);
condition.push('jz', endOfTrue);
this.operators[jumpLocation] = 'j';
this.operands[jumpLocation] = this.operands.length;
this.operators[conditionLocation] = 'jz';
this.operands[conditionLocation] = endOfTrue;
} else {
error('PS Function: error parsing conditional.');
}

20
test/unit/function_spec.js
View File

@ -38,13 +38,13 @@ describe('function', function() {
}
it('parses empty programs', function() {
var output = parse('{}');
expect(output.length).toEqual(0);
expect(output[0].length).toEqual(0);
});
it('parses positive numbers', function() {
var number = 999;
var program = parse('{ ' + number + ' }');
var expectedProgram = [
['push', number]
['push'], [number]
];
expect(program).toMatchArray(expectedProgram);
});
@ -52,7 +52,7 @@ describe('function', function() {
var number = -999;
var program = parse('{ ' + number + ' }');
var expectedProgram = [
['push', number]
['push'], [number]
];
expect(program).toMatchArray(expectedProgram);
});
@ -60,32 +60,28 @@ describe('function', function() {
var number = 3.3;
var program = parse('{ ' + number + ' }');
var expectedProgram = [
['push', number]
['push'], [number]
];
expect(program).toMatchArray(expectedProgram);
});
it('parses operators', function() {
var program = parse('{ sub }');
var expectedProgram = [
['sub']
['sub'], [null]
];
expect(program).toMatchArray(expectedProgram);
});
it('parses if statements', function() {
var program = parse('{ { 99 } if }');
var expectedProgram = [
['jz', 2],
['push', 99]
['jz', 'push'], [2, 99]
];
expect(program).toMatchArray(expectedProgram);
});
it('parses ifelse statements', function() {
var program = parse('{ { 99 } { 44 } ifelse }');
var expectedProgram = [
['jz', 3],
['push', 99],
['j', 4],
['push', 44]
['jz', 'push', 'j', 'push'], [3, 99, 4, 44]
];
expect(program).toMatchArray(expectedProgram);
});
@ -100,7 +96,7 @@ describe('function', function() {
var stream = new StringStream(program);
var parser = new PostScriptParser(new PostScriptLexer(stream));
var code = parser.parse();
var evaluator = new PostScriptEvaluator(code);
var evaluator = new PostScriptEvaluator(code[0], code[1]);
var output = evaluator.execute();
return output;
}