json_parse = (function () {

// This is a function that can parse a JSON text, producing a JavaScript

// data structure. It is a simple, recursive descent parser. It does not use

// eval or regular expressions, so it can be used as a model for implementing

// a JSON parser in other languages.

// We are defining the function inside of another function to avoid creating

// global variables.

var at, // The index of the current character

ch, // The current character

escapee = {

'"': '"',

'\\': '\\',

'/': '/',

b: '\b',

f: '\f',

n: '\n',

r: '\r',

t: '\t'

},

text,

error = function (m) {

// Call error when something is wrong.

throw {

name: 'SyntaxError',

message: m,

at: at,

text: text

};

},

next = function (c) {

// If a c parameter is provided, verify that it matches the current character.

if (c && c !== ch) {

error("Expected '" + c + "' instead of '" + ch + "'");

}

// Get the next character. When there are no more characters,

// return the empty string.

ch = text.charAt(at);

at += 1;

return ch;

},

number = function () {

// Parse a number value.

var number,

string = '';

if (ch === '-') {

string = '-';

next('-');

}

while (ch >= '0' && ch <= '9') {

string += ch;

next();

}

if (ch === '.') {

string += '.';

while (next() && ch >= '0' && ch <= '9') {

string += ch;

}

}

if (ch === 'e' || ch === 'E') {

string += ch;

next();

if (ch === '-' || ch === '+') {

string += ch;

next();

}

while (ch >= '0' && ch <= '9') {

string += ch;

next();

}

}

number = +string;

if (isNaN(number)) {

error("Bad number");

} else {

return number;

}

},

string = function () {

// Parse a string value.

var hex,

i,

string = '',

uffff;

// When parsing for string values, we must look for " and \ characters.

if (ch === '"') {

while (next()) {

if (ch === '"') {

next();

return string;

} else if (ch === '\\') {

next();

if (ch === 'u') {

uffff = 0;

for (i = 0; i < 4; i += 1) {

hex = parseInt(next(), 16);

if (!isFinite(hex)) {

break;

}

uffff = uffff * 16 + hex;

}

string += String.fromCharCode(uffff);

} else if (typeof escapee[ch] === 'string') {

string += escapee[ch];

} else {

break;

}

} else {

string += ch;

}

}

}

error("Bad string");

},

white = function () {

// Skip whitespace.

while (ch && ch <= ' ') {

next();

}

},

word = function () {

// true, false, or null.

switch (ch) {

case 't':

next('t');

next('r');

next('u');

next('e');

return true;

case 'f':

next('f');

next('a');

next('l');

next('s');

next('e');

return false;

case 'n':

next('n');

next('u');

next('l');

next('l');

return null;

}

error("Unexpected '" + ch + "'");

},

value, // Place holder for the value function.

array = function () {

// Parse an array value.

var array = [];

if (ch === '[') {

next('[');

white();

if (ch === ']') {

next(']');

return array; // empty array

}

while (ch) {

array.push(value());

white();

if (ch === ']') {

next(']');

return array;

}

next(',');

white();

}

}

error("Bad array");

},

object = function () {

// Parse an object value.

var key,

object = {};

if (ch === '{') {

next('{');

white();

if (ch === '}') {

next('}');

return object; // empty object

}

while (ch) {

key = string();

white();

next(':');

if (Object.hasOwnProperty.call(object, key)) {

error('Duplicate key "' + key + '"');

}

object[key] = value();

white();

if (ch === '}') {

next('}');

return object;

}

next(',');

white();

}

}

error("Bad object");

};

value = function () {

// Parse a JSON value. It could be an object, an array, a string, a number,

// or a word.

white();

switch (ch) {

case '{':

return object();

case '[':

return array();

case '"':

return string();

case '-':

return number();

default:

return ch >= '0' && ch <= '9' ? number() : word();

}

};

// Return the json_parse function. It will have access to all of the above

// functions and variables.

return function (source, reviver) {

var result;

text = source;

at = 0;

ch = ' ';

result = value();

white();

if (ch) {

error("Syntax error");

}

// If there is a reviver function, we recursively walk the new structure,

// passing each name/value pair to the reviver function for possible

// transformation, starting with a temporary root object that holds the result

// in an empty key. If there is not a reviver function, we simply return the

// result.

return typeof reviver === 'function' ? (function walk(holder, key) {

var k, v, value = holder[key];

if (value && typeof value === 'object') {

for (k in value) {

if (Object.hasOwnProperty.call(value, k)) {

v = walk(value, k);

if (v !== undefined) {

value[k] = v;

} else {

delete value[k];

}

}

}

}

return reviver.call(holder, key, value);

}({'': result}, '')) : result;

};

}());