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794 lines
27 KiB
JavaScript
794 lines
27 KiB
JavaScript
/* Emits the generated code for the AST. */
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PEG.compiler.emitter = function(ast) {
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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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* formatCode("foo", "bar"); // "foo\nbar"
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* formatCode("foo", "${bar}", { bar: "baz" }); // "foo\nbaz"
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* formatCode("foo", "${bar}"); // throws Error
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* formatCode("foo", "${bar|string}", { bar: "baz" }); // "foo\n\"baz\""
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* formatCode("foo", "${bar|eeek}", { bar: "baz" }); // throws Error
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* formatCode("foo", "${bar}", { bar: " baz\nqux" }); // "foo\n baz\n qux"
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*/
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function formatCode() {
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function interpolateVariablesInParts(parts) {
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return 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 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 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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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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function resultVar(index) { return "result" + index; }
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function posVar(index) { return "pos" + index; }
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var emit = buildNodeVisitor({
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grammar: function(node) {
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var initializerCode = node.initializer !== null
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? emit(node.initializer)
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: "";
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var parseFunctionTableItems = [];
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for (var name in node.rules) {
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parseFunctionTableItems.push(quote(name) + ": parse_" + name);
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}
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parseFunctionTableItems.sort();
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var parseFunctionDefinitions = [];
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for (var name in node.rules) {
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parseFunctionDefinitions.push(emit(node.rules[name]));
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}
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return formatCode(
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"(function(){",
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" /* Generated by PEG.js @VERSION (http://pegjs.majda.cz/). */",
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" ",
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" var result = {",
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" /*",
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" * Parses the input with a generated parser. If the parsing is successfull,",
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" * returns a value explicitly or implicitly specified by the grammar from",
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" * which the parser was generated (see |PEG.buildParser|). If the parsing is",
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" * unsuccessful, throws |PEG.parser.SyntaxError| describing the error.",
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" */",
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" parse: function(input, startRule) {",
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" var parseFunctions = {",
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" ${parseFunctionTableItems}",
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" };",
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" ",
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" if (startRule !== undefined) {",
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" if (parseFunctions[startRule] === undefined) {",
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" throw new Error(\"Invalid rule name: \" + quote(startRule) + \".\");",
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" }",
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" } else {",
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" startRule = ${startRule|string};",
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" }",
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" ",
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" var pos = 0;",
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" var reportFailures = 0;", // 0 = report, anything > 0 = do not report
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" var rightmostFailuresPos = 0;",
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" var rightmostFailuresExpected = [];",
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" var cache = {};",
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" ",
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/* This needs to be in sync with |padLeft| in utils.js. */
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" function padLeft(input, padding, length) {",
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" var result = input;",
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" ",
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" var padLength = length - input.length;",
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" for (var i = 0; i < padLength; i++) {",
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" result = padding + result;",
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" }",
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" ",
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" return result;",
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" }",
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" ",
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/* This needs to be in sync with |escape| in utils.js. */
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" function escape(ch) {",
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" var charCode = ch.charCodeAt(0);",
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" var escapeChar;",
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" var length;",
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" ",
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" if (charCode <= 0xFF) {",
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" escapeChar = 'x';",
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" length = 2;",
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" } else {",
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" escapeChar = 'u';",
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" length = 4;",
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" }",
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" ",
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" return '\\\\' + escapeChar + padLeft(charCode.toString(16).toUpperCase(), '0', length);",
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" }",
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" ",
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/* This needs to be in sync with |quote| in utils.js. */
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" function quote(s) {",
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" /*",
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" * ECMA-262, 5th ed., 7.8.4: All characters may appear literally in a",
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" * string literal except for the closing quote character, backslash,",
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" * carriage return, line separator, paragraph separator, and line feed.",
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" * Any character may appear in the form of an escape sequence.",
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" *",
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" * For portability, we also escape escape all control and non-ASCII",
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" * characters. Note that \"\\0\" and \"\\v\" escape sequences are not used",
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" * because JSHint does not like the first and IE the second.",
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" */",
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" return '\"' + s",
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" .replace(/\\\\/g, '\\\\\\\\') // backslash",
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" .replace(/\"/g, '\\\\\"') // closing quote character",
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" .replace(/\\x08/g, '\\\\b') // backspace",
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" .replace(/\\t/g, '\\\\t') // horizontal tab",
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" .replace(/\\n/g, '\\\\n') // line feed",
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" .replace(/\\f/g, '\\\\f') // form feed",
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" .replace(/\\r/g, '\\\\r') // carriage return",
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" .replace(/[\\x00-\\x07\\x0B\\x0E-\\x1F\\x80-\\uFFFF]/g, escape)",
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" + '\"';",
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" }",
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" ",
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" function matchFailed(failure) {",
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" if (pos < rightmostFailuresPos) {",
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" return;",
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" }",
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" ",
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" if (pos > rightmostFailuresPos) {",
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" rightmostFailuresPos = pos;",
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" rightmostFailuresExpected = [];",
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" }",
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" ",
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" rightmostFailuresExpected.push(failure);",
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" }",
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" ",
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" ${parseFunctionDefinitions}",
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" ",
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" function buildErrorMessage() {",
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" function buildExpected(failuresExpected) {",
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" failuresExpected.sort();",
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" ",
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" var lastFailure = null;",
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" var failuresExpectedUnique = [];",
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" for (var i = 0; i < failuresExpected.length; i++) {",
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" if (failuresExpected[i] !== lastFailure) {",
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" failuresExpectedUnique.push(failuresExpected[i]);",
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" lastFailure = failuresExpected[i];",
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" }",
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" }",
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" ",
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" switch (failuresExpectedUnique.length) {",
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" case 0:",
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" return 'end of input';",
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" case 1:",
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" return failuresExpectedUnique[0];",
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" default:",
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" return failuresExpectedUnique.slice(0, failuresExpectedUnique.length - 1).join(', ')",
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" + ' or '",
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" + failuresExpectedUnique[failuresExpectedUnique.length - 1];",
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" }",
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" }",
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" ",
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" var expected = buildExpected(rightmostFailuresExpected);",
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" var actualPos = Math.max(pos, rightmostFailuresPos);",
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" var actual = actualPos < input.length",
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" ? quote(input.charAt(actualPos))",
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" : 'end of input';",
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" ",
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" return 'Expected ' + expected + ' but ' + actual + ' found.';",
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" }",
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" ",
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" function computeErrorPosition() {",
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" /*",
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" * The first idea was to use |String.split| to break the input up to the",
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" * error position along newlines and derive the line and column from",
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" * there. However IE's |split| implementation is so broken that it was",
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" * enough to prevent it.",
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" */",
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" ",
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" var line = 1;",
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" var column = 1;",
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" var seenCR = false;",
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" ",
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" for (var i = 0; i < rightmostFailuresPos; i++) {",
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" var ch = input.charAt(i);",
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" if (ch === '\\n') {",
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" if (!seenCR) { line++; }",
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" column = 1;",
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" seenCR = false;",
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" } else if (ch === '\\r' | ch === '\\u2028' || ch === '\\u2029') {",
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" line++;",
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" column = 1;",
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" seenCR = true;",
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" } else {",
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" column++;",
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" seenCR = false;",
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" }",
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" }",
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" ",
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" return { line: line, column: column };",
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" }",
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" ",
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" ${initializerCode}",
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" ",
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" var result = parseFunctions[startRule]();",
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" ",
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" /*",
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" * The parser is now in one of the following three states:",
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" *",
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" * 1. The parser successfully parsed the whole input.",
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" *",
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" * - |result !== null|",
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" * - |pos === input.length|",
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" * - |rightmostFailuresExpected| may or may not contain something",
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" *",
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" * 2. The parser successfully parsed only a part of the input.",
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" *",
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" * - |result !== null|",
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" * - |pos < input.length|",
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" * - |rightmostFailuresExpected| may or may not contain something",
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" *",
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" * 3. The parser did not successfully parse any part of the input.",
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" *",
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" * - |result === null|",
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" * - |pos === 0|",
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" * - |rightmostFailuresExpected| contains at least one failure",
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" *",
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" * All code following this comment (including called functions) must",
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" * handle these states.",
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" */",
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" if (result === null || pos !== input.length) {",
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" var errorPosition = computeErrorPosition();",
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" throw new this.SyntaxError(",
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" buildErrorMessage(),",
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" errorPosition.line,",
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" errorPosition.column",
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" );",
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" }",
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" ",
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" return result;",
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" },",
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" ",
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" /* Returns the parser source code. */",
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" toSource: function() { return this._source; }",
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" };",
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" ",
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" /* Thrown when a parser encounters a syntax error. */",
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" ",
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" result.SyntaxError = function(message, line, column) {",
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" this.name = 'SyntaxError';",
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" this.message = message;",
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" this.line = line;",
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" this.column = column;",
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" };",
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" ",
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" result.SyntaxError.prototype = Error.prototype;",
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" ",
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" return result;",
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"})()",
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{
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initializerCode: initializerCode,
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parseFunctionTableItems: parseFunctionTableItems.join(",\n"),
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parseFunctionDefinitions: parseFunctionDefinitions.join("\n\n"),
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startRule: node.startRule
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}
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);
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},
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initializer: function(node) {
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return node.code;
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},
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rule: function(node) {
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var context = {
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resultIndex: 0,
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posIndex: 0
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};
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var resultVars = map(range(node.resultStackDepth), resultVar);
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var posVars = map(range(node.posStackDepth), posVar);
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var resultVarsCode = resultVars.length > 0 ? "var " + resultVars.join(", ") + ";" : "";
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var posVarsCode = posVars.length > 0 ? "var " + posVars.join(", ") + ";" : "";
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if (node.displayName !== null) {
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var setReportFailuresCode = formatCode(
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"reportFailures++;"
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);
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var restoreReportFailuresCode = formatCode(
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"reportFailures--;"
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);
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var reportFailureCode = formatCode(
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"if (reportFailures === 0 && ${resultVar} === null) {",
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" matchFailed(${displayName|string});",
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"}",
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{
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displayName: node.displayName,
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resultVar: resultVar(context.resultIndex)
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}
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);
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} else {
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var setReportFailuresCode = "";
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var restoreReportFailuresCode = "";
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var reportFailureCode = "";
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}
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return formatCode(
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"function parse_${name}() {",
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" var cacheKey = '${name}@' + pos;",
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" var cachedResult = cache[cacheKey];",
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" if (cachedResult) {",
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" pos = cachedResult.nextPos;",
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" return cachedResult.result;",
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" }",
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" ",
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" ${resultVarsCode}",
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" ${posVarsCode}",
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" ",
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" ${setReportFailuresCode}",
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" ${code}",
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" ${restoreReportFailuresCode}",
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" ${reportFailureCode}",
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" ",
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" cache[cacheKey] = {",
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" nextPos: 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: node.name,
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resultVarsCode: resultVarsCode,
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posVarsCode: posVarsCode,
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setReportFailuresCode: setReportFailuresCode,
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restoreReportFailuresCode: restoreReportFailuresCode,
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reportFailureCode: reportFailureCode,
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code: emit(node.expression, context),
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resultVar: resultVar(context.resultIndex)
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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 functions
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* is as follows.
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*
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* The code fragment tries to match a part of the input starting with the
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* position indicated in |pos|. That position may point past the end of the
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* input.
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*
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* * If the code fragment matches the input, it advances |pos| to point to
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* the first chracter following the matched part of the input and sets
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* variable with a name computed by calling
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* |resultVar(context.resultIndex)| to an appropriate value. This value is
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* always non-|null|.
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*
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* * If the code fragment does not match the input, it returns with |pos|
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* set to the original value and it sets a variable with a name computed
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* by calling |resultVar(context.resultIndex)| to |null|.
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*
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* The code can use variables with names computed by calling
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*
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* |resultVar(context.resultIndex + i)|
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*
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* and
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*
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* |posVar(context.posIndex + i)|
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*
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* where |i| >= 1 to store necessary data (return values and positions). It
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* won't use any other variables.
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*/
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choice: function(node, context) {
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var code, nextAlternativesCode;
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for (var i = node.alternatives.length - 1; i >= 0; i--) {
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nextAlternativesCode = i !== node.alternatives.length - 1
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? formatCode(
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"if (${resultVar} === null) {",
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" ${code}",
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"}",
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{
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code: code,
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resultVar: resultVar(context.resultIndex)
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|
}
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)
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: "";
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code = formatCode(
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"${currentAlternativeCode}",
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|
"${nextAlternativesCode}",
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|
{
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|
currentAlternativeCode: emit(node.alternatives[i], context),
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nextAlternativesCode: nextAlternativesCode
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|
}
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);
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}
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return code;
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},
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sequence: function(node, context) {
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|
var elementResultVars = map(node.elements, function(element, i) {
|
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return resultVar(context.resultIndex + i);
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|
});
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|
|
var code = formatCode(
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|
"${resultVar} = ${elementResultVarArray};",
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|
{
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resultVar: resultVar(context.resultIndex),
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|
elementResultVarArray: "[" + elementResultVars.join(", ") + "]"
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|
}
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);
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|
var elementContext;
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for (var i = node.elements.length - 1; i >= 0; i--) {
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elementContext = {
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resultIndex: context.resultIndex + i,
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posIndex: context.posIndex + 1
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};
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code = formatCode(
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"${elementCode}",
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|
"if (${elementResultVar} !== null) {",
|
|
" ${code}",
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|
"} else {",
|
|
" ${resultVar} = null;",
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|
" pos = ${posVar};",
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"}",
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|
{
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elementCode: emit(node.elements[i], elementContext),
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elementResultVar: elementResultVars[i],
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|
code: code,
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|
posVar: posVar(context.posIndex),
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resultVar: resultVar(context.resultIndex)
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}
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);
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}
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return formatCode(
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"${posVar} = pos;",
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"${code}",
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{
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code: code,
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posVar: posVar(context.posIndex)
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}
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);
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},
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labeled: function(node, context) {
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return emit(node.expression, context);
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|
},
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|
|
simple_and: function(node, context) {
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|
var expressionContext = {
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resultIndex: context.resultIndex,
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posIndex: context.posIndex + 1
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};
|
|
|
|
return formatCode(
|
|
"${posVar} = pos;",
|
|
"reportFailures++;",
|
|
"${expressionCode}",
|
|
"reportFailures--;",
|
|
"if (${resultVar} !== null) {",
|
|
" ${resultVar} = '';",
|
|
" pos = ${posVar};",
|
|
"} else {",
|
|
" ${resultVar} = null;",
|
|
"}",
|
|
{
|
|
expressionCode: emit(node.expression, expressionContext),
|
|
posVar: posVar(context.posIndex),
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
},
|
|
|
|
simple_not: function(node, context) {
|
|
var expressionContext = {
|
|
resultIndex: context.resultIndex,
|
|
posIndex: context.posIndex + 1
|
|
};
|
|
|
|
return formatCode(
|
|
"${posVar} = pos;",
|
|
"reportFailures++;",
|
|
"${expressionCode}",
|
|
"reportFailures--;",
|
|
"if (${resultVar} === null) {",
|
|
" ${resultVar} = '';",
|
|
"} else {",
|
|
" ${resultVar} = null;",
|
|
" pos = ${posVar};",
|
|
"}",
|
|
{
|
|
expressionCode: emit(node.expression, expressionContext),
|
|
posVar: posVar(context.posIndex),
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
},
|
|
|
|
semantic_and: function(node, context) {
|
|
return formatCode(
|
|
"${resultVar} = (function() {${actionCode}})() ? '' : null;",
|
|
{
|
|
actionCode: node.code,
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
},
|
|
|
|
semantic_not: function(node, context) {
|
|
return formatCode(
|
|
"${resultVar} = (function() {${actionCode}})() ? null : '';",
|
|
{
|
|
actionCode: node.code,
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
},
|
|
|
|
optional: function(node, context) {
|
|
return formatCode(
|
|
"${expressionCode}",
|
|
"${resultVar} = ${resultVar} !== null ? ${resultVar} : '';",
|
|
{
|
|
expressionCode: emit(node.expression, context),
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
},
|
|
|
|
zero_or_more: function(node, context) {
|
|
var expressionContext = {
|
|
resultIndex: context.resultIndex + 1,
|
|
posIndex: context.posIndex
|
|
};
|
|
|
|
return formatCode(
|
|
"${resultVar} = [];",
|
|
"${expressionCode}",
|
|
"while (${expressionResultVar} !== null) {",
|
|
" ${resultVar}.push(${expressionResultVar});",
|
|
" ${expressionCode}",
|
|
"}",
|
|
{
|
|
expressionCode: emit(node.expression, expressionContext),
|
|
expressionResultVar: resultVar(context.resultIndex + 1),
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
},
|
|
|
|
one_or_more: function(node, context) {
|
|
var expressionContext = {
|
|
resultIndex: context.resultIndex + 1,
|
|
posIndex: context.posIndex
|
|
};
|
|
|
|
return formatCode(
|
|
"${expressionCode}",
|
|
"if (${expressionResultVar} !== null) {",
|
|
" ${resultVar} = [];",
|
|
" while (${expressionResultVar} !== null) {",
|
|
" ${resultVar}.push(${expressionResultVar});",
|
|
" ${expressionCode}",
|
|
" }",
|
|
"} else {",
|
|
" ${resultVar} = null;",
|
|
"}",
|
|
{
|
|
expressionCode: emit(node.expression, expressionContext),
|
|
expressionResultVar: resultVar(context.resultIndex + 1),
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
},
|
|
|
|
action: function(node, context) {
|
|
/*
|
|
* In case of sequences, we splat their elements into function arguments
|
|
* one by one. Example:
|
|
*
|
|
* start: a:"a" b:"b" c:"c" { alert(arguments.length) } // => 3
|
|
*
|
|
* This behavior is reflected in this function.
|
|
*/
|
|
|
|
var expressionContext = {
|
|
resultIndex: context.resultIndex,
|
|
posIndex: context.posIndex + 1
|
|
};
|
|
|
|
if (node.expression.type === "sequence") {
|
|
var formalParams = [];
|
|
var actualParams = [];
|
|
|
|
var elements = node.expression.elements;
|
|
var elementsLength = elements.length;
|
|
for (var i = 0; i < elementsLength; i++) {
|
|
if (elements[i].type === "labeled") {
|
|
formalParams.push(elements[i].label);
|
|
actualParams.push(resultVar(context.resultIndex) + "[" + i + "]");
|
|
}
|
|
}
|
|
} else if (node.expression.type === "labeled") {
|
|
var formalParams = [node.expression.label];
|
|
var actualParams = [resultVar(context.resultIndex)];
|
|
} else {
|
|
var formalParams = [];
|
|
var actualParams = [];
|
|
}
|
|
|
|
return formatCode(
|
|
"${posVar} = pos;",
|
|
"${expressionCode}",
|
|
"if (${resultVar} !== null) {",
|
|
" ${resultVar} = (function(${formalParams}) {${actionCode}})(${actualParams});",
|
|
"}",
|
|
"if (${resultVar} === null) {",
|
|
" pos = ${posVar};",
|
|
"}",
|
|
{
|
|
expressionCode: emit(node.expression, expressionContext),
|
|
actionCode: node.code,
|
|
formalParams: formalParams.join(", "),
|
|
actualParams: actualParams.join(", "),
|
|
posVar: posVar(context.posIndex),
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
},
|
|
|
|
rule_ref: function(node, context) {
|
|
return formatCode(
|
|
"${resultVar} = ${ruleMethod}();",
|
|
{
|
|
ruleMethod: "parse_" + node.name,
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
},
|
|
|
|
literal: function(node, context) {
|
|
var length = node.value.length;
|
|
var testCode = length === 1
|
|
? formatCode(
|
|
"input.charCodeAt(pos) === ${valueCharCode}",
|
|
{ valueCharCode: node.value.charCodeAt(0) }
|
|
)
|
|
: formatCode(
|
|
"input.substr(pos, ${length}) === ${value|string}",
|
|
{
|
|
value: node.value,
|
|
length: length
|
|
}
|
|
);
|
|
|
|
return formatCode(
|
|
"if (${testCode}) {",
|
|
" ${resultVar} = ${value|string};",
|
|
" pos += ${length};",
|
|
"} else {",
|
|
" ${resultVar} = null;",
|
|
" if (reportFailures === 0) {",
|
|
" matchFailed(${valueQuoted|string});",
|
|
" }",
|
|
"}",
|
|
{
|
|
testCode: testCode,
|
|
value: node.value,
|
|
valueQuoted: quote(node.value),
|
|
length: length,
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
},
|
|
|
|
any: function(node, context) {
|
|
return formatCode(
|
|
"if (input.length > pos) {",
|
|
" ${resultVar} = input.charAt(pos);",
|
|
" pos++;",
|
|
"} else {",
|
|
" ${resultVar} = null;",
|
|
" if (reportFailures === 0) {",
|
|
" matchFailed('any character');",
|
|
" }",
|
|
"}",
|
|
{ resultVar: resultVar(context.resultIndex) }
|
|
);
|
|
},
|
|
|
|
"class": function(node, context) {
|
|
if (node.parts.length > 0) {
|
|
var regexp = "/^["
|
|
+ (node.inverted ? "^" : "")
|
|
+ map(node.parts, function(part) {
|
|
return part instanceof Array
|
|
? quoteForRegexpClass(part[0])
|
|
+ "-"
|
|
+ quoteForRegexpClass(part[1])
|
|
: quoteForRegexpClass(part);
|
|
}).join("")
|
|
+ "]/";
|
|
} else {
|
|
/*
|
|
* Stupid IE considers regexps /[]/ and /[^]/ syntactically invalid, so
|
|
* we translate them into euqivalents it can handle.
|
|
*/
|
|
var regexp = node.inverted ? "/^[\\S\\s]/" : "/^(?!)/";
|
|
}
|
|
|
|
return formatCode(
|
|
"if (${regexp}.test(input.charAt(pos))) {",
|
|
" ${resultVar} = input.charAt(pos);",
|
|
" pos++;",
|
|
"} else {",
|
|
" ${resultVar} = null;",
|
|
" if (reportFailures === 0) {",
|
|
" matchFailed(${rawText|string});",
|
|
" }",
|
|
"}",
|
|
{
|
|
regexp: regexp,
|
|
rawText: node.rawText,
|
|
resultVar: resultVar(context.resultIndex)
|
|
}
|
|
);
|
|
}
|
|
});
|
|
|
|
return emit(ast);
|
|
};
|