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Anton Kotenko
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4 files changed

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4 files changed

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‎data

+12
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{
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"firstName": "Yurii",
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"lastName": "Gorbylov",
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"contactInfo": {
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"email": "yuriygorbylov@gmail.com",
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"phoneNumber": "+38(063)195-51-31"
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},
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"skills": [
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"java8",
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"scala"
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]
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}

‎fakejq.js

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var MYJSON = require('./json.js');
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var data = Buffer(0);
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process.stdin.on('data', function (chunk) {
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data = Buffer.concat([data, chunk]);
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});
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process.stdin.on('end', function () {
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var obj;
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try {
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obj = MYJSON.parse(data.toString('utf8'));
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} catch (e) {
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console.error("bad input", e);
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process.exit();
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}
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var path = (process.argv[2] || '').replace(/\.+/g, '.').replace(/^\./, '');
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if (path) {
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console.log(path.split('.').reduce(function (value, key) {
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if (value[key] === undefined) {
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console.error("there are no such key" );
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process.exit();
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}
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return value[key];
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}, obj));
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} else {
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console.log(obj);
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}
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});
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process.stdin.resume();

‎json.js

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var trace = function (parser, msg) {
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console.log(msg, parser._string, parser._position);
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};
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var attachTraser = function (cls) {
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var tracedCls = function () {
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return cls.apply(this, arguments);
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};
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tracedCls.prototype = Object.keys(cls.prototype).reduce(function (newPrototype, propName) {
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if (cls.prototype[propName] instanceof Function) {
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newPrototype[propName] = function () {
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var result;
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trace(this, propName);
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result = cls.prototype[propName].apply(this, arguments);
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trace(this, propName + ' exit');
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return result;
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}
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} else {
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newPrototype[propName] = cls.prototype[propName];
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}
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return newPrototype;
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}, {});
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return tracedCls;
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};
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var Util = require('util');
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var ParseError = function (parser, expectation) {
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var message = "ParseError at " + parser._position + " expectations " + expectation;
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Error.call(this, message);
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};
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Util.inherits(ParseError, Error);
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var SymbolTraits = {
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_NUMBERS_INDEX: function () {
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var index = {};
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for (var i = 0; i < 10; i++) {
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index[i] = true;
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}
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return index;
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}(),
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_WHITESPACE_INDEX: {
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" ": true,
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"\t": true,
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"\n" : true
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},
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isNumber: function (symbol) {
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return this._NUMBERS_INDEX[symbol]
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},
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isWhiteSpace: function (symbol) {
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return this._WHITESPACE_INDEX[symbol];
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}
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};
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var JSONParser = function (string) {
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this._string = string;
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this._position = 0;
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this._length = string.length;
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};
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JSONParser.prototype = {
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_TOKENS: {
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OBJECT_OPEN: '{',
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OBJECT_CLOSE: '}',
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ARRAY_OPEN: '[',
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ARRAY_CLOSE: ']',
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QUOTE: '"',
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NULL: 'null',
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FALSE: 'false',
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TRUE: 'true',
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COLUMN: ':',
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COMA: ',',
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BACKSLASH: '\\',
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MINUS: '-',
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DOT: '.'
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},
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parse: function () {
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var value = this._parse();
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//it's allowed to skip whitespaces at the end of the json
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this._skipWhiteSpace();
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if (this._position !== this._length) {
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throw new ParseError(this, "end of stirng to parse");
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}
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return value;
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},
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_parse: function () {
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while(this._position <= this._length) {
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if (this._lookAheadForToken(this._TOKENS.OBJECT_OPEN)) {
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return this._consumeObject();
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} else if (this._lookAheadForToken(this._TOKENS.ARRAY_OPEN)) {
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return this._consumeArray();
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} else if (this._lookAheadForToken(this._TOKENS.QUOTE)) {
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return this._consumeString();
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} else if (this._lookAheadForToken(this._TOKENS.NULL)) {
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this._consumeToken(this._TOKENS.NULL);
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return null;
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} else if (this._lookAheadForToken(this._TOKENS.TRUE)) {
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this._consumeToken(this._TOKENS.TRUE);
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return true;
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} else if (this._lookAheadForToken(this._TOKENS.FALSE)) {
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this._consumeToken(this._TOKENS.FALSE);
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return false;
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} else if (this._lookAheadForNumber()) {
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return this._consumeNumber();
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} else {
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throw new ParseError(this, "null/true/false/number");
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}
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}
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},
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_consumeObject: function () {
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var key,
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result = {};
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this._consumeToken(this._TOKENS.OBJECT_OPEN);
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do {
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this._skipWhiteSpace();
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if (this._lookAheadForToken(this._TOKENS.OBJECT_CLOSE)) {
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this._consumeToken(this._TOKENS.OBJECT_CLOSE);
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break;
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}
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key = this._requireObjectKey();
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this._requireColumn();
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this._skipWhiteSpace();
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result[key] = this._parse();
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this._skipWhiteSpace();
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if (this._lookAheadForToken(this._TOKENS.COMA)) {
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this._consumeToken(this._TOKENS.COMA);
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}
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} while (true);
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return result;
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},
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_consumeArray: function () {
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var result = [];
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this._consumeToken(this._TOKENS.ARRAY_OPEN);
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do {
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this._skipWhiteSpace();
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if (this._lookAheadForToken(this._TOKENS.ARRAY_CLOSE)) {
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this._consumeToken(this._TOKENS.ARRAY_CLOSE);
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break;
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}
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this._skipWhiteSpace();
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result.push(this._parse());
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this._skipWhiteSpace();
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if (this._lookAheadForToken(this._TOKENS.COMA)) {
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this._consumeToken(this._TOKENS.COMA);
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}
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} while (true);
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return result;
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},
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_requireObjectKey: function () {
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this._skipWhiteSpace();
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if (this._lookAheadForToken(this._TOKENS.QUOTE)) {
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return this._consumeString();
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}
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throw new ParseError(this, 'string as object key expected');
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},
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_requireColumn: function () {
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this._skipWhiteSpace();
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if (this._lookAheadForToken(this._TOKENS.COLUMN)) {
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this._consumeToken(this._TOKENS.COLUMN);
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} else {
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throw new ParseError(this, 'column expected');
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}
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},
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_consumeString: function () {
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var stringEscapeFlag = false,
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parsedString = [];
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this._consumeToken(this._TOKENS.QUOTE);
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do {
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if (stringEscapeFlag) {
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parsedString.push(this._consumeCurrentSymbol());
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stringEscapeFlag = false;
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} else if (this._lookAheadForToken(this._TOKENS.QUOTE)) {
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this._consumeToken(this._TOKENS.QUOTE);
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break;
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} else if (this._lookAheadForToken(this._TOKENS.BACKSLASH)) {
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this._consumeToken(this._TOKENS.BACKSLASH);
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stringEscapeFlag = true;
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} else {
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parsedString.push(this._consumeCurrentSymbol());
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}
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} while (true);
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return parsedString.join("");
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},
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_consumeNumber: function () {
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var symbol,
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haveMinus = false,
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haveDot = false,
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initialPosition = this._position,
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symbols = [];
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while (this._position < this._length) {
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symbol = this._getCurrentSymbol();
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if (SymbolTraits.isNumber(symbol)) {
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symbols.push(this._consumeCurrentSymbol());
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} else if (this._lookAheadForToken(this._TOKENS.MINUS)) {
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if (haveMinus) {
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throw new ParseError(this, "unexpected minus");
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}
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symbols.push(this._consumeCurrentSymbol());
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haveMinus = true;
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} else if (this._lookAheadForToken(this._TOKENS.DOT)) {
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if (haveDot) {
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throw new ParseError(this, "unexpected dot");
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}
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symbols.push(this._consumeCurrentSymbol());
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haveDot = true;
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} else {
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break;
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}
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}
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return Number(symbols.join(''));
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},
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_lookAheadForToken: function (pattern) {
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return [].every.call(pattern, function (patternLetter, i) {
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var offset = this._position + i;
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if (offset >= this.length) {
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return false;
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}
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return this._string[offset] === patternLetter;
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}, this);
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},
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_consumeToken: function (token) {
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this._position += token.length;
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},
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_lookAheadForNumber: function () {
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var currentSymbol = this._getCurrentSymbol();
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return SymbolTraits.isNumber(currentSymbol) || currentSymbol === this._TOKENS.MINUS;
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},
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_skipWhiteSpace: function () {
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while (this._position < this._length) {
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if (!SymbolTraits.isWhiteSpace([this._string[this._position]])) {
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return;
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}
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this._position++;
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}
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},
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_advancePosition: function () {
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if (this._position >= this._length) {
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throw new ParseError(this, "unexpected eos");
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}
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this._position++;
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},
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_getCurrentSymbol: function () {
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if (this._position >= this._length) {
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throw new ParseError(this, "unexpected eos");
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}
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return this._string[this._position];
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},
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_consumeCurrentSymbol: function () {
285+
var symbol = this._getCurrentSymbol();
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this._advancePosition();
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return symbol;
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}
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};
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//JSONParser = attachTraser(JSONParser);
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module.exports = {
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parse: function (string) {
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return (new JSONParser(string)).parse();
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}
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};

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