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jssource/src_files/include/javascript/yui3/build/json/json-parse.js

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+/*
+Copyright (c) 2009, Yahoo! Inc. All rights reserved.
+Code licensed under the BSD License:
+http://developer.yahoo.net/yui/license.txt
+version: 3.0.0
+build: 1549
+*/
+YUI.add('json-parse', function(Y) {
+
+/**
+ * <p>The JSON module adds support for serializing JavaScript objects into
+ * JSON strings and parsing JavaScript objects from strings in JSON format.</p>
+ *
+ * <p>The JSON namespace is added to your YUI instance including static methods
+ * Y.JSON.parse(..) and Y.JSON.stringify(..).</p>
+ *
+ * <p>The functionality and method signatures follow the ECMAScript 5
+ * specification.  In browsers with native JSON support, the native
+ * implementation is used.</p>
+ *
+ * <p>The <code>json</code> module is a rollup of <code>json-parse</code> and
+ * <code>json-stringify</code>.</p>
+ * 
+ * <p>As their names suggest, <code>json-parse</code> adds support for parsing
+ * JSON data (Y.JSON.parse) and <code>json-stringify</code> for serializing
+ * JavaScript data into JSON strings (Y.JSON.stringify).  You may choose to
+ * include either of the submodules individually if you don't need the
+ * complementary functionality, or include the rollup for both.</p>
+ *
+ * @module json
+ * @class JSON
+ * @static
+ */
+
+/**
+ * Provides Y.JSON.parse method to accept JSON strings and return native
+ * JavaScript objects.
+ *
+ * @module json
+ * @submodule json-parse
+ * @for JSON
+ * @static
+ */
+
+
+// All internals kept private for security reasons
+
+
+    /**
+     * Alias to native browser implementation of the JSON object if available.
+     *
+     * @property Native
+     * @type {Object}
+     * @private
+     */
+var _JSON  = Y.config.win.JSON,
+    Native = (Object.prototype.toString.call(_JSON) === '[object JSON]' && _JSON),
+
+    /**
+     * Replace certain Unicode characters that JavaScript may handle incorrectly
+     * during eval--either by deleting them or treating them as line
+     * endings--with escape sequences.
+     * IMPORTANT NOTE: This regex will be used to modify the input if a match is
+     * found.
+     *
+     * @property _UNICODE_EXCEPTIONS
+     * @type {RegExp}
+     * @private
+     */
+    _UNICODE_EXCEPTIONS = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
+
+
+    /**
+     * First step in the safety evaluation.  Regex used to replace all escape
+     * sequences (i.e. "\\", etc) with '@' characters (a non-JSON character).
+     *
+     * @property _ESCAPES
+     * @type {RegExp}
+     * @private
+     */
+    _ESCAPES = /\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g,
+
+    /**
+     * Second step in the safety evaluation.  Regex used to replace all simple
+     * values with ']' characters.
+     *
+     * @property _VALUES
+     * @type {RegExp}
+     * @private
+     */
+    _VALUES  = /"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g,
+
+    /**
+     * Third step in the safety evaluation.  Regex used to remove all open
+     * square brackets following a colon, comma, or at the beginning of the
+     * string.
+     *
+     * @property _BRACKETS
+     * @type {RegExp}
+     * @private
+     */
+    _BRACKETS = /(?:^|:|,)(?:\s*\[)+/g,
+
+    /**
+     * Final step in the safety evaluation.  Regex used to test the string left
+     * after all previous replacements for invalid characters.
+     *
+     * @property _UNSAFE
+     * @type {RegExp}
+     * @private
+     */
+    _UNSAFE = /[^\],:{}\s]/,
+    
+    /**
+     * Replaces specific unicode characters with their appropriate \unnnn
+     * format. Some browsers ignore certain characters during eval.
+     *
+     * @method escapeException
+     * @param c {String} Unicode character
+     * @return {String} the \unnnn escapement of the character
+     * @private
+     */
+    _escapeException = function (c) {
+        return '\\u'+('0000'+(+(c.charCodeAt(0))).toString(16)).slice(-4);
+    },
+
+    /**
+     * Traverses nested objects, applying a reviver function to each (key,value)
+     * from the scope if the key:value's containing object.  The value returned
+     * from the function will replace the original value in the key:value pair.
+     * If the value returned is undefined, the key will be omitted from the
+     * returned object.
+     *
+     * @method _revive
+     * @param data {MIXED} Any JavaScript data
+     * @param reviver {Function} filter or mutation function
+     * @return {MIXED} The results of the filtered data
+     * @private
+     */
+    _revive = function (data, reviver) {
+        var walk = function (o,key) {
+            var k,v,value = o[key];
+            if (value && typeof value === 'object') {
+                for (k in value) {
+                    if (value.hasOwnProperty(k)) {
+                        v = walk(value, k);
+                        if (v === undefined) {
+                            delete value[k];
+                        } else {
+                            value[k] = v;
+                        }
+                    }
+                }
+            }
+            return reviver.call(o,key,value);
+        };
+
+        return typeof reviver === 'function' ? walk({'':data},'') : data;
+    },
+
+    /**
+     * Parse a JSON string, returning the native JavaScript representation.
+     *
+     * @param s {string} JSON string data
+     * @param reviver {function} (optional) function(k,v) passed each key value
+     *          pair of object literals, allowing pruning or altering values
+     * @return {MIXED} the native JavaScript representation of the JSON string
+     * @throws SyntaxError
+     * @method parse
+     * @static
+     */
+    // JavaScript implementation in lieu of native browser support.  Based on
+    // the json2.js library from http://json.org
+    _parse = function (s,reviver) {
+        if (typeof s === 'string') {
+            // Replace certain Unicode characters that are otherwise handled
+            // incorrectly by some browser implementations.
+            // NOTE: This modifies the input if such characters are found!
+            s = s.replace(_UNICODE_EXCEPTIONS, _escapeException);
+            
+            // Test for any remaining invalid characters
+            if (!_UNSAFE.test(s.replace(_ESCAPES,'@').
+                                 replace(_VALUES,']').
+                                 replace(_BRACKETS,''))) {
+
+                // Eval the text into a JavaScript data structure, apply any
+                // reviver function, and return
+                return _revive( eval('(' + s + ')'), reviver );
+            }
+        }
+
+        throw new SyntaxError('JSON.parse');
+    };
+    
+Y.namespace('JSON').parse = function (s,reviver) {
+    return Native && Y.JSON.useNativeParse ?
+        Native.parse(s,reviver) : _parse(s,reviver);
+};
+
+/**
+ * Leverage native JSON parse if the browser has a native implementation.
+ * In general, this is a good idea.  See the Known Issues section in the
+ * JSON user guide for caveats.  The default value is true for browsers with
+ * native JSON support.
+ *
+ * @property useNativeParse
+ * @type Boolean
+ * @default true
+ * @static
+ */
+Y.JSON.useNativeParse = !!Native;
+
+
+}, '3.0.0' );