350 lines
10 KiB
JavaScript
350 lines
10 KiB
JavaScript
// Copyright 2006 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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* @fileoverview JSON utility functions.
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* @author arv@google.com (Erik Arvidsson)
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*/
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goog.provide('goog.json');
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goog.provide('goog.json.Serializer');
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/**
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* Tests if a string is an invalid JSON string. This only ensures that we are
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* not using any invalid characters
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* @param {string} s The string to test.
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* @return {boolean} True if the input is a valid JSON string.
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* @private
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*/
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goog.json.isValid_ = function(s) {
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// All empty whitespace is not valid.
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if (/^\s*$/.test(s)) {
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return false;
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}
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// This is taken from http://www.json.org/json2.js which is released to the
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// public domain.
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// Changes: We dissallow \u2028 Line separator and \u2029 Paragraph separator
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// inside strings. We also treat \u2028 and \u2029 as whitespace which they
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// are in the RFC but IE and Safari does not match \s to these so we need to
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// include them in the reg exps in all places where whitespace is allowed.
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// We allowed \x7f inside strings because some tools don't escape it,
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// e.g. http://www.json.org/java/org/json/JSONObject.java
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// Parsing happens in three stages. In the first stage, we run the text
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// against regular expressions that look for non-JSON patterns. We are
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// especially concerned with '()' and 'new' because they can cause invocation,
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// and '=' because it can cause mutation. But just to be safe, we want to
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// reject all unexpected forms.
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// We split the first stage into 4 regexp operations in order to work around
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// crippling inefficiencies in IE's and Safari's regexp engines. First we
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// replace all backslash pairs with '@' (a non-JSON character). Second, we
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// replace all simple value tokens with ']' characters. Third, we delete all
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// open brackets that follow a colon or comma or that begin the text. Finally,
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// we look to see that the remaining characters are only whitespace or ']' or
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// ',' or ':' or '{' or '}'. If that is so, then the text is safe for eval.
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// Don't make these static since they have the global flag.
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var backslashesRe = /\\["\\\/bfnrtu]/g;
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var simpleValuesRe =
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/"[^"\\\n\r\u2028\u2029\x00-\x08\x0a-\x1f]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g;
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var openBracketsRe = /(?:^|:|,)(?:[\s\u2028\u2029]*\[)+/g;
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var remainderRe = /^[\],:{}\s\u2028\u2029]*$/;
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return remainderRe.test(s.replace(backslashesRe, '@').
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replace(simpleValuesRe, ']').
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replace(openBracketsRe, ''));
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};
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/**
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* Parses a JSON string and returns the result. This throws an exception if
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* the string is an invalid JSON string.
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*
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* Note that this is very slow on large strings. If you trust the source of
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* the string then you should use unsafeParse instead.
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*
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* @param {*} s The JSON string to parse.
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* @return {Object} The object generated from the JSON string.
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*/
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goog.json.parse = function(s) {
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var o = String(s);
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if (goog.json.isValid_(o)) {
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/** @preserveTry */
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try {
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return /** @type {Object} */ (eval('(' + o + ')'));
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} catch (ex) {
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}
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}
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throw Error('Invalid JSON string: ' + o);
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};
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/**
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* Parses a JSON string and returns the result. This uses eval so it is open
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* to security issues and it should only be used if you trust the source.
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*
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* @param {string} s The JSON string to parse.
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* @return {Object} The object generated from the JSON string.
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*/
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goog.json.unsafeParse = function(s) {
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return /** @type {Object} */ (eval('(' + s + ')'));
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};
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/**
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* JSON replacer, as defined in Section 15.12.3 of the ES5 spec.
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*
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* TODO(nicksantos): Array should also be a valid replacer.
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*
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* @typedef {function(this:Object, string, *): *}
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*/
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goog.json.Replacer;
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/**
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* JSON reviver, as defined in Section 15.12.2 of the ES5 spec.
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*
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* @typedef {function(this:Object, string, *): *}
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*/
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goog.json.Reviver;
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/**
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* Serializes an object or a value to a JSON string.
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*
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* @param {*} object The object to serialize.
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* @param {?goog.json.Replacer=} opt_replacer A replacer function
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* called for each (key, value) pair that determines how the value
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* should be serialized. By defult, this just returns the value
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* and allows default serialization to kick in.
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* @throws Error if there are loops in the object graph.
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* @return {string} A JSON string representation of the input.
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*/
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goog.json.serialize = function(object, opt_replacer) {
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// NOTE(nicksantos): Currently, we never use JSON.stringify.
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//
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// The last time I evaluated this, JSON.stringify had subtle bugs and behavior
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// differences on all browsers, and the performance win was not large enough
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// to justify all the issues. This may change in the future as browser
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// implementations get better.
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//
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// assertSerialize in json_test contains if branches for the cases
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// that fail.
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return new goog.json.Serializer(opt_replacer).serialize(object);
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};
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/**
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* Class that is used to serialize JSON objects to a string.
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* @param {?goog.json.Replacer=} opt_replacer Replacer.
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* @constructor
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*/
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goog.json.Serializer = function(opt_replacer) {
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/**
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* @type {goog.json.Replacer|null|undefined}
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* @private
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*/
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this.replacer_ = opt_replacer;
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};
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/**
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* Serializes an object or a value to a JSON string.
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*
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* @param {*} object The object to serialize.
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* @throws Error if there are loops in the object graph.
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* @return {string} A JSON string representation of the input.
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*/
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goog.json.Serializer.prototype.serialize = function(object) {
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var sb = [];
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this.serialize_(object, sb);
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return sb.join('');
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};
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/**
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* Serializes a generic value to a JSON string
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* @private
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* @param {*} object The object to serialize.
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* @param {Array} sb Array used as a string builder.
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* @throws Error if there are loops in the object graph.
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*/
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goog.json.Serializer.prototype.serialize_ = function(object, sb) {
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switch (typeof object) {
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case 'string':
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this.serializeString_(/** @type {string} */ (object), sb);
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break;
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case 'number':
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this.serializeNumber_(/** @type {number} */ (object), sb);
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break;
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case 'boolean':
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sb.push(object);
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break;
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case 'undefined':
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sb.push('null');
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break;
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case 'object':
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if (object == null) {
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sb.push('null');
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break;
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}
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if (goog.isArray(object)) {
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this.serializeArray(/** @type {!Array} */ (object), sb);
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break;
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}
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// should we allow new String, new Number and new Boolean to be treated
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// as string, number and boolean? Most implementations do not and the
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// need is not very big
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this.serializeObject_(/** @type {Object} */ (object), sb);
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break;
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case 'function':
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// Skip functions.
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// TODO(user) Should we return something here?
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break;
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default:
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throw Error('Unknown type: ' + typeof object);
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}
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};
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/**
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* Character mappings used internally for goog.string.quote
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* @private
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* @type {Object}
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*/
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goog.json.Serializer.charToJsonCharCache_ = {
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'\"': '\\"',
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'\\': '\\\\',
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'/': '\\/',
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'\b': '\\b',
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'\f': '\\f',
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'\n': '\\n',
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'\r': '\\r',
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'\t': '\\t',
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'\x0B': '\\u000b' // '\v' is not supported in JScript
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};
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/**
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* Regular expression used to match characters that need to be replaced.
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* The S60 browser has a bug where unicode characters are not matched by
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* regular expressions. The condition below detects such behaviour and
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* adjusts the regular expression accordingly.
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* @private
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* @type {RegExp}
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*/
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goog.json.Serializer.charsToReplace_ = /\uffff/.test('\uffff') ?
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/[\\\"\x00-\x1f\x7f-\uffff]/g : /[\\\"\x00-\x1f\x7f-\xff]/g;
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/**
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* Serializes a string to a JSON string
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* @private
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* @param {string} s The string to serialize.
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* @param {Array} sb Array used as a string builder.
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*/
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goog.json.Serializer.prototype.serializeString_ = function(s, sb) {
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// The official JSON implementation does not work with international
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// characters.
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sb.push('"', s.replace(goog.json.Serializer.charsToReplace_, function(c) {
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// caching the result improves performance by a factor 2-3
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if (c in goog.json.Serializer.charToJsonCharCache_) {
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return goog.json.Serializer.charToJsonCharCache_[c];
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}
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var cc = c.charCodeAt(0);
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var rv = '\\u';
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if (cc < 16) {
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rv += '000';
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} else if (cc < 256) {
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rv += '00';
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} else if (cc < 4096) { // \u1000
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rv += '0';
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}
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return goog.json.Serializer.charToJsonCharCache_[c] = rv + cc.toString(16);
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}), '"');
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};
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/**
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* Serializes a number to a JSON string
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* @private
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* @param {number} n The number to serialize.
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* @param {Array} sb Array used as a string builder.
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*/
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goog.json.Serializer.prototype.serializeNumber_ = function(n, sb) {
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sb.push(isFinite(n) && !isNaN(n) ? n : 'null');
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};
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/**
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* Serializes an array to a JSON string
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* @param {Array} arr The array to serialize.
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* @param {Array} sb Array used as a string builder.
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* @protected
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*/
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goog.json.Serializer.prototype.serializeArray = function(arr, sb) {
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var l = arr.length;
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sb.push('[');
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var sep = '';
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for (var i = 0; i < l; i++) {
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sb.push(sep);
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var value = arr[i];
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this.serialize_(
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this.replacer_ ? this.replacer_.call(arr, String(i), value) : value,
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sb);
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sep = ',';
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}
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sb.push(']');
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};
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/**
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* Serializes an object to a JSON string
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* @private
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* @param {Object} obj The object to serialize.
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* @param {Array} sb Array used as a string builder.
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*/
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goog.json.Serializer.prototype.serializeObject_ = function(obj, sb) {
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sb.push('{');
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var sep = '';
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for (var key in obj) {
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if (Object.prototype.hasOwnProperty.call(obj, key)) {
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var value = obj[key];
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// Skip functions.
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// TODO(ptucker) Should we return something for function properties?
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if (typeof value != 'function') {
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sb.push(sep);
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this.serializeString_(key, sb);
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sb.push(':');
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this.serialize_(
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this.replacer_ ? this.replacer_.call(obj, key, value) : value,
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sb);
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sep = ',';
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}
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}
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}
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sb.push('}');
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};
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