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522 lines
16 KiB
JavaScript
522 lines
16 KiB
JavaScript
/*
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* PEG.js compiler.
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*
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* The runtime.js file must be included before this file.
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*/
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(function() {
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/* ===== PEG ===== */
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/*
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* Generates a parser from a specified grammar and start rule and returns it.
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*
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* The grammar may be either an object or a string. If it is an object, it
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* must contain AST of the parsing expressions (i.e. instances of |PEG.Grammar.*
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* classes| for the grammar rules in its properties. If it is a string, it is
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* parsed using |PEG.grammarParser| to obtain the grammar AST and thus it must
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* be in a format that this parser accepts (see the source code for details).
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*
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* The start rule may be unspecified, in which case "start" is used.
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*
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* Throws |PEG.Grammar.GrammarError| if the grammar definition is not object nor
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* string or if it contains an error. Note that not all errors are detected
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* during the generation and some may protrude to the generated parser and cause
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* its malfunction.
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*/
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PEG.buildParser = function(grammar, startRule) {
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startRule = startRule || "start";
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switch (typeof(grammar)) {
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case "object":
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var ast = grammar;
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break;
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case "string":
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var ast = PEG.grammarParser.parse(grammar);
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break;
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default:
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throw new PEG.Grammar.GrammarError("Grammar must be object or string.");
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}
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if (ast[startRule] === undefined) {
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throw new PEG.Grammar.GrammarError("Missing \"" + startRule + "\" rule.");
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}
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return PEG.Compiler.compileParser(ast, startRule);
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};
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/* ===== PEG.Grammar ===== */
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/* Namespace with grammar AST nodes. */
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PEG.Grammar = {};
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/* ===== PEG.GrammarError ===== */
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/* Thrown when the grammar contains an error. */
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PEG.Grammar.GrammarError = function(message) {
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this.name = "PEG.Grammar.GrammarError";
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this.message = message;
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};
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PEG.Grammar.GrammarError.prototype = Error.prototype;
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/* ===== PEG.Grammar.* ===== */
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PEG.Grammar.Rule = function(name, displayName, expression) {
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this._name = name;
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this._displayName = displayName;
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this._expression = expression;
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};
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PEG.Grammar.Rule.prototype = {
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getName: function() { return this._name; }
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};
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PEG.Grammar.Literal = function(value) { this._value = value; };
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PEG.Grammar.Any = function() {};
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PEG.Grammar.Sequence = function(elements) { this._elements = elements; };
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PEG.Grammar.Choice = function(alternatives) {
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this._alternatives = alternatives;
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};
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PEG.Grammar.ZeroOrMore = function(element) { this._element = element; };
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PEG.Grammar.NotPredicate = function(expression) {
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this._expression = expression;
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};
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PEG.Grammar.RuleRef = function(name) { this._name = name; };
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PEG.Grammar.Action = function(expression, action) {
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this._expression = expression;
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this._action = action;
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};
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/* ===== PEG.Compiler ===== */
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PEG.Compiler = {
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/*
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* Takes parts of code, interpolates variables inside them and joins them with
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* a newline.
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*
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* Variables are delimited with "${" and "}" and their names must be valid
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* identifiers (i.e. they must match [a-zA-Z_][a-zA-Z0-9_]*). Variable values
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* are specified as properties of the last parameter (if this is an object,
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* otherwise empty variable set is assumed). Undefined variables result in
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* throwing |Error|.
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*
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* There can be a filter specified after the variable name, prefixed with "|".
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* The filter name must be a valid identifier. The only recognized filter
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* right now is "string", which quotes the variable value as a JavaScript
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* string. Unrecognized filters result in throwing |Error|.
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*
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* If any part has multiple lines and the first line is indented by some
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* amount of whitespace (as defined by the /\s+/ JavaScript regular
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* expression), second to last lines are indented by the same amount of
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* whitespace. This results in nicely indented multiline code in variables
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* without making the templates look ugly.
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*
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* Examples:
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*
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* PEG.Compiler.formatCode("foo", "bar"); // "foo\nbar"
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* PEG.Compiler.formatCode(
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* "foo", "${bar}",
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* { bar: "baz" }
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* ); // "foo\nbaz"
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* PEG.Compiler.formatCode("foo", "${bar}"); // throws Error
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* PEG.Compiler.formatCode(
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* "foo", "${bar|string}",
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* { bar: "baz" }
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* ); // "foo\n\"baz\""
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* PEG.Compiler.formatCode(
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* "foo", "${bar|eeek}",
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* { bar: "baz" }
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* ); // throws Error
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* PEG.Compiler.formatCode(
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* "foo", "${bar}",
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* { bar: " baz\nqux" }
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* ); // "foo\n baz\n qux"
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*/
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formatCode: function() {
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function interpolateVariablesInParts(parts) {
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return PEG.ArrayUtils.map(parts, function(part) {
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return part.replace(
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/\$\{([a-zA-Z_][a-zA-Z0-9_]*)(\|([a-zA-Z_][a-zA-Z0-9_]*))?\}/g,
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function(match, name, dummy, filter) {
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var value = vars[name];
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if (value === undefined) {
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throw new Error("Undefined variable: \"" + name + "\".");
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}
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if (filter !== undefined && filter != "") { // JavaScript engines differ here.
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if (filter === "string") {
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return PEG.StringUtils.quote(value);
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} else {
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throw new Error("Unrecognized filter: \"" + filter + "\".");
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}
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} else {
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return value;
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}
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}
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);
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});
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}
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function indentMultilineParts(parts) {
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return PEG.ArrayUtils.map(parts, function(part) {
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if (!/\n/.test(part)) { return part; }
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var firstLineWhitespacePrefix = part.match(/^\s*/)[0];
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var lines = part.split("\n");
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var linesIndented = [lines[0]].concat(
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PEG.ArrayUtils.map(lines.slice(1), function(line) {
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return firstLineWhitespacePrefix + line;
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})
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);
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return linesIndented.join("\n");
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});
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}
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var args = Array.prototype.slice.call(arguments);
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var vars = args[args.length - 1] instanceof Object ? args.pop() : {};
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return indentMultilineParts(interpolateVariablesInParts(args)).join("\n");
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},
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_uniqueIdentifierCounters: {},
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_resetUniqueIdentifierCounters: function() {
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this._uniqueIdentifierCounters = {};
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},
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/* Generates a unique identifier with specified prefix. */
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generateUniqueIdentifier: function(prefix) {
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this._uniqueIdentifierCounters[prefix]
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= this._uniqueIdentifierCounters[prefix] || 0;
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return prefix + this._uniqueIdentifierCounters[prefix]++;
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},
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/*
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* Generates a parser from a specified grammar and start rule.
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*/
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compileParser: function(grammar, startRule) {
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/*
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* This ensures that the same grammar and start rule always generate exactly
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* the same parser.
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*/
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this._resetUniqueIdentifierCounters();
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var parseFunctionDefinitions = [];
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for (var key in grammar) {
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parseFunctionDefinitions.push(grammar[key].compile());
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}
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var source = this.formatCode(
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"(function(){",
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" var result = new PEG.Parser(${startRule|string});",
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" ",
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" ${parseFunctionDefinitions}",
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" ",
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" return result;",
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"})()",
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{
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parseFunctionDefinitions: parseFunctionDefinitions.join("\n\n"),
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startRule: startRule
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}
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);
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var result = eval(source);
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result._source = source;
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return result;
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}
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};
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PEG.Grammar.Rule.prototype.compile = function() {
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var resultVar = PEG.Compiler.generateUniqueIdentifier("result");
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if (this._displayName !== null) {
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var setReportMatchFailuresCode = PEG.Compiler.formatCode(
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"var savedReportMatchFailures = context.reportMatchFailures;",
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"context.reportMatchFailures = false;"
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);
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var restoreReportMatchFailuresCode = PEG.Compiler.formatCode(
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"context.reportMatchFailures = savedReportMatchFailures;"
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);
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var reportMatchFailureCode = PEG.Compiler.formatCode(
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"if (context.reportMatchFailures && ${resultVar} === null) {",
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" this._matchFailed(new PEG.Parser.NamedRuleMatchFailure(${displayName|string}));",
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"}",
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{
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displayName: this._displayName,
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resultVar: resultVar
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}
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);
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} else {
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var setReportMatchFailuresCode = "";
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var restoreReportMatchFailuresCode = "";
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var reportMatchFailureCode = "";
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}
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return PEG.Compiler.formatCode(
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"result._parse_${name} = function(context) {",
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" this._cache[${name|string}] = this._cache[${name|string}] || [];",
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" var cachedResult = this._cache[${name|string}][this._pos];",
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" if (cachedResult !== undefined) {",
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" this._pos = cachedResult.nextPos;",
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" return cachedResult.result;",
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" }",
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" ",
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" var pos = this._pos;",
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" ",
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" ${setReportMatchFailuresCode}",
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" ${code}",
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" ${restoreReportMatchFailuresCode}",
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" ${reportMatchFailureCode}",
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" ",
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" this._cache[${name|string}][pos] = {",
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" nextPos: this._pos,",
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" result: ${resultVar}",
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" };",
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" return ${resultVar};",
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"};",
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{
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name: this._name,
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setReportMatchFailuresCode: setReportMatchFailuresCode,
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restoreReportMatchFailuresCode: restoreReportMatchFailuresCode,
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reportMatchFailureCode: reportMatchFailureCode,
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code: this._expression.compile(resultVar),
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resultVar: resultVar
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}
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);
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};
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/*
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* The contract for all code fragments generated by the following |compile|
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* methods is as follows:
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*
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* * The code fragment should try to match a part of the input starting with the
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* position indicated in |this._pos|. That position may point past the end of
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* the input.
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*
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* * If the code fragment matches the input, it advances |this._pos| after the
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* matched part of the input and sets variable with a name stored in
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* |resultVar| to appropriate value, which is always non-null.
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*
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* * If the code fragment does not match the input, it does not change
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* |this._pos| and it sets a variable with a name stored in |resultVar| to
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* |null|.
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*/
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PEG.Grammar.Literal.prototype.compile = function(resultVar) {
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return PEG.Compiler.formatCode(
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"if (this._input.substr(this._pos, ${length}) === ${value|string}) {",
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" var ${resultVar} = ${value|string};",
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" this._pos += ${length};",
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"} else {",
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" var ${resultVar} = null;",
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" if (context.reportMatchFailures) {",
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" this._matchFailed(new PEG.Parser.LiteralMatchFailure(${value|string}));",
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" }",
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"}",
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{
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value: this._value,
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length: this._value.length,
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resultVar: resultVar
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}
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);
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};
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PEG.Grammar.Any.prototype.compile = function(resultVar) {
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return PEG.Compiler.formatCode(
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"if (this._input.length > this._pos) {",
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" var ${resultVar} = this._input[this._pos];",
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" this._pos++;",
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"} else {",
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" var ${resultVar} = null;",
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" if (context.reportMatchFailures) {",
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" this._matchFailed(new PEG.Parser.AnyMatchFailure());",
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" }",
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"}",
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{ resultVar: resultVar }
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);
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};
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PEG.Grammar.Sequence.prototype.compile = function(resultVar) {
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var savedPosVar = PEG.Compiler.generateUniqueIdentifier("savedPos");
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var elementResultVars = PEG.ArrayUtils.map(this._elements, function() {
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return PEG.Compiler.generateUniqueIdentifier("result")
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});
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var code = PEG.Compiler.formatCode(
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"var ${resultVar} = ${elementResultVarArray};",
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{
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resultVar: resultVar,
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elementResultVarArray: "[" + elementResultVars.join(", ") + "]"
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}
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);
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for (var i = this._elements.length - 1; i >= 0; i--) {
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code = PEG.Compiler.formatCode(
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"${elementCode}",
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"if (${elementResultVar} !== null) {",
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" ${code}",
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"} else {",
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" var ${resultVar} = null;",
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" this._pos = ${savedPosVar};",
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"}",
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{
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elementCode: this._elements[i].compile(elementResultVars[i]),
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elementResultVar: elementResultVars[i],
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code: code,
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savedPosVar: savedPosVar,
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resultVar: resultVar
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}
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);
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}
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return PEG.Compiler.formatCode(
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"var ${savedPosVar} = this._pos;",
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"${code}",
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{
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code: code,
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savedPosVar: savedPosVar
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}
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);
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};
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PEG.Grammar.Choice.prototype.compile = function(resultVar) {
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var code = PEG.Compiler.formatCode(
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"var ${resultVar} = null;",
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{ resultVar: resultVar }
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);
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for (var i = this._alternatives.length - 1; i >= 0; i--) {
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var alternativeResultVar = PEG.Compiler.generateUniqueIdentifier("result");
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code = PEG.Compiler.formatCode(
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"${alternativeCode}",
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"if (${alternativeResultVar} !== null) {",
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" var ${resultVar} = ${alternativeResultVar};",
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"} else {",
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" ${code};",
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"}",
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{
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alternativeCode: this._alternatives[i].compile(alternativeResultVar),
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alternativeResultVar: alternativeResultVar,
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code: code,
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resultVar: resultVar
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}
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);
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}
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return code;
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};
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PEG.Grammar.ZeroOrMore.prototype.compile = function(resultVar) {
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var elementResultVar = PEG.Compiler.generateUniqueIdentifier("result");
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return PEG.Compiler.formatCode(
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"var ${resultVar} = [];",
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"${elementCode}",
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"while (${elementResultVar} !== null) {",
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" ${resultVar}.push(${elementResultVar});",
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" ${elementCode}",
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"}",
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{
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elementCode: this._element.compile(elementResultVar),
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elementResultVar: elementResultVar,
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resultVar: resultVar
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}
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);
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};
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PEG.Grammar.NotPredicate.prototype.compile = function(resultVar) {
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var savedPosVar = PEG.Compiler.generateUniqueIdentifier("savedPos");
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var savedReportMatchFailuresVar = PEG.Compiler.generateUniqueIdentifier("savedReportMatchFailuresVar");
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var expressionResultVar = PEG.Compiler.generateUniqueIdentifier("result");
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return PEG.Compiler.formatCode(
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"var ${savedPosVar} = this._pos;",
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"var ${savedReportMatchFailuresVar} = context.reportMatchFailures;",
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"context.reportMatchFailures = false;",
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"${expressionCode}",
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"context.reportMatchFailures = ${savedReportMatchFailuresVar};",
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"if (${expressionResultVar} === null) {",
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" var ${resultVar} = '';",
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"} else {",
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" var ${resultVar} = null;",
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" this._pos = ${savedPosVar};",
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"}",
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{
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expressionCode: this._expression.compile(expressionResultVar),
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expressionResultVar: expressionResultVar,
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savedPosVar: savedPosVar,
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savedReportMatchFailuresVar: savedReportMatchFailuresVar,
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resultVar: resultVar
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}
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);
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};
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PEG.Grammar.RuleRef.prototype.compile = function(resultVar) {
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return PEG.Compiler.formatCode(
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"var ${resultVar} = this.${ruleMethod}(context);",
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{
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ruleMethod: "_parse_" + this._name,
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resultVar: resultVar
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}
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);
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};
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PEG.Grammar.Action.prototype.compile = function(resultVar) {
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var expressionResultVar = PEG.Compiler.generateUniqueIdentifier("result");
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if (typeof(this._action) === "function") {
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var actionFunction = this._action.toString();
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} else {
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var actionCode = this._action.replace(
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/\$(\d+)/g,
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function(match, digits) {
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return PEG.Compiler.formatCode(
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"(arguments[${index}])",
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{ index: parseInt(digits) - 1 }
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);
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}
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)
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var actionFunction = PEG.Compiler.formatCode(
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"function() { ${actionCode} }",
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{ actionCode: actionCode }
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);
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}
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/*
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* In case of sequences, we splat their elements into function arguments one
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* by one. Example:
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*
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* start: "a" "b" "c" { alert(arguments.length) } // => "3"
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*/
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var invokeFunctionName = this._expression instanceof PEG.Grammar.Sequence
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? "apply"
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: "call";
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return PEG.Compiler.formatCode(
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"${expressionCode}",
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"var ${resultVar} = ${expressionResultVar} !== null",
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" ? (${actionFunction}).${invokeFunctionName}(this, ${expressionResultVar})",
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" : null;",
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{
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expressionCode: this._expression.compile(expressionResultVar),
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expressionResultVar: expressionResultVar,
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actionFunction: actionFunction,
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invokeFunctionName: invokeFunctionName,
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resultVar: resultVar
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}
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);
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};
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})();
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