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// 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 [email protected] (Erik Arvidsson)
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 */
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goog.provide('goog.json');
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goog.provide('goog.json.Replacer');
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goog.provide('goog.json.Reviver');
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goog.provide('goog.json.Serializer');
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/**
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 * @define {boolean} If true, use the native JSON parsing API.
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 * NOTE: The default {@code goog.json.parse} implementation is able to handle
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 * invalid JSON. JSPB used to produce invalid JSON which is not the case
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 * anymore so this is safe to enable for parsing JSPB. Using native JSON is
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 * faster and safer than the default implementation using {@code eval}.
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 */
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goog.define('goog.json.USE_NATIVE_JSON', false);
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/**
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 * @define {boolean} If true, try the native JSON parsing API first. If it
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 * fails, log an error and use {@code eval} instead. This is useful when
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 * transitioning to {@code goog.json.USE_NATIVE_JSON}. The error logger needs to
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 * be set by {@code goog.json.setErrorLogger}. If it is not set then the error
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 * is ignored.
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 */
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goog.define('goog.json.TRY_NATIVE_JSON', false);
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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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 */
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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, but only when followed
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  // by a colon, comma, closing bracket or end of string. 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+)?)[\s\u2028\u2029]*(?=:|,|]|}|$)/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(
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      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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 * Logs a parsing error in {@code JSON.parse} solvable by using {@code eval}
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 * if {@code goog.json.TRY_NATIVE_JSON} is enabled.
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 * @private {function(string, !Error)} The first parameter is the error message,
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 *     the second is the exception thrown by {@code JSON.parse}.
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 */
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goog.json.errorLogger_ = goog.nullFunction;
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/**
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 * Sets an error logger to use if there's a recoverable parsing error and {@code
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 * goog.json.TRY_NATIVE_JSON} is enabled.
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 * @param {function(string, !Error)} errorLogger The first parameter is the
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 *     error message, the second is the exception thrown by {@code JSON.parse}.
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 */
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goog.json.setErrorLogger = function(errorLogger) {
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  goog.json.errorLogger_ = errorLogger;
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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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 * @throws Error if s is invalid JSON.
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 * @return {Object} The object generated from the JSON string, or null.
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 */
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goog.json.parse = goog.json.USE_NATIVE_JSON ?
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    /** @type {function(*):Object} */ (goog.global['JSON']['parse']) :
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    function(s) {
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      var error;
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      if (goog.json.TRY_NATIVE_JSON) {
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        try {
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          return goog.global['JSON']['parse'](s);
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        } catch (ex) {
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          error = ex;
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        }
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      }
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      var o = String(s);
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      if (goog.json.isValid(o)) {
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        try {
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          var result = /** @type {?Object} */ (eval('(' + o + ')'));
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          if (error) {
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            goog.json.errorLogger_('Invalid JSON: ' + o, error);
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          }
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          return result;
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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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 * @deprecated Use JSON.parse if possible or goog.json.parse.
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 */
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goog.json.unsafeParse = goog.json.USE_NATIVE_JSON ?
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    /** @type {function(string):Object} */ (goog.global['JSON']['parse']) :
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    function(s) {
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      var error;
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      if (goog.json.TRY_NATIVE_JSON) {
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        try {
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          return goog.global['JSON']['parse'](s);
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        } catch (ex) {
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          error = ex;
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        }
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      }
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      var result = /** @type {?Object} */ (eval('(' + s + ')'));
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      if (error) {
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        goog.json.errorLogger_('Invalid JSON: ' + s, error);
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      }
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      return result;
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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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 * @see http://ecma-international.org/ecma-262/5.1/#sec-15.12.3
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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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 * @see http://ecma-international.org/ecma-262/5.1/#sec-15.12.3
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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 = goog.json.USE_NATIVE_JSON ?
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    /** @type {function(*, ?goog.json.Replacer=):string} */
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    (goog.global['JSON']['stringify']) :
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    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
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      // behavior differences on all browsers, and the performance win was not
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      // large enough to justify all the issues. This may change in the future
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      // as browser 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.serializeInternal(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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 * @protected
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 * @param {*} object The object to serialize.
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 * @param {Array<string>} 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.serializeInternal = function(object, sb) {
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  if (object == null) {
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    // undefined == null so this branch covers undefined as well as null
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    sb.push('null');
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    return;
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  }
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  if (typeof object == 'object') {
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    if (goog.isArray(object)) {
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      this.serializeArray(object, sb);
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      return;
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    } else if (
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        object instanceof String || object instanceof Number ||
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        object instanceof Boolean) {
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      object = object.valueOf();
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      // Fall through to switch below.
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    } else {
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      this.serializeObject_(/** @type {!Object} */ (object), sb);
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      return;
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    }
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  }
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  switch (typeof object) {
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    case 'string':
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      this.serializeString_(object, sb);
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      break;
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    case 'number':
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      this.serializeNumber_(object, sb);
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      break;
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    case 'boolean':
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      sb.push(String(object));
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      break;
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    case 'function':
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      sb.push('null');
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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 :
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    /[\\\"\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<string>} 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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    var rv = goog.json.Serializer.charToJsonCharCache_[c];
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    if (!rv) {
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      rv = '\\u' + (c.charCodeAt(0) | 0x10000).toString(16).substr(1);
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      goog.json.Serializer.charToJsonCharCache_[c] = rv;
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    }
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    return rv;
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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<string>} 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) ? String(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<string>} arr The array to serialize.
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 * @param {Array<string>} 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.serializeInternal(
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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<string>} 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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      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.serializeInternal(
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            this.replacer_ ? this.replacer_.call(obj, key, value) : value, 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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