Adding ChromeVox as a component extensions (enabled only for ChromeOS, for no...

chrome/browser/resources/access_chromevox/common/chromevox_json.js

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+goog.provide('cvox.ChromeVoxJSON');
+
+/**
+ * @fileoverview A simple wrapper around the JSON APIs.
+ * If it is possible to use the browser's built in native JSON, then
+ * cvox.ChromeVoxJSON is the same as JSON.
+ * If the page has its own version of JSON, cvox.ChromeVoxJSON will use its
+ * own implementation (rather than the version of JSON on the page
+ * which may be outdated/broken).
+ */
+
+if (!cvox.ChromeVoxJSON) {
+  /**
+   * @type {Object}
+   */
+  cvox.ChromeVoxJSON = {};
+}
+
+if (JSON.toString() == '[object JSON]') {
+  cvox.ChromeVoxJSON = JSON;
+} else {
+  /*
+   *  JSON implementation renamed to cvox.ChromeVoxJSON.
+   *  This only gets called if the page has its own version of JSON.
+   *
+   *  Based on:
+   *  http://www.JSON.org/json2.js
+   *  2010-03-20
+   *
+   *  Public Domain.
+   *
+   *  NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
+   *
+   *  See http://www.JSON.org/js.html
+   */
+  (function() {
+    function f(n) {
+      // Format integers to have at least two digits.
+      return n < 10 ? '0' + n : n;
+    }
+
+    if (typeof Date.prototype.toJSON !== 'function') {
+
+      Date.prototype.toJSON = function(key) {
+
+        return isFinite(this.valueOf()) ?
+                   this.getUTCFullYear() + '-' +
+                f(this.getUTCMonth() + 1) + '-' +
+                f(this.getUTCDate()) + 'T' +
+                f(this.getUTCHours()) + ':' +
+                f(this.getUTCMinutes()) + ':' +
+                f(this.getUTCSeconds()) + 'Z' : 'null';
+      };
+
+      String.prototype.toJSON =
+      Number.prototype.toJSON =
+      Boolean.prototype.toJSON = function(key) {
+        return this.valueOf();
+      };
+    }
+
+    var cx = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
+        escapable = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
+        gap,
+        indent,
+        meta = {    // table of character substitutions
+          '\b': '\\b',
+          '\t': '\\t',
+          '\n': '\\n',
+          '\f': '\\f',
+          '\r': '\\r',
+          '"' : '\\"',
+          '\\': '\\\\'
+        },
+        rep;
+
+
+    function quote(string) {
+
+      // If the string contains no control characters, no quote characters, and
+      // no backslash characters, then we can safely slap some quotes around it.
+      // Otherwise we must also replace the offending characters with safe
+      // escape sequences.
+
+      escapable.lastIndex = 0;
+      return escapable.test(string) ?
+          '"' + string.replace(escapable, function(a) {
+               var c = meta[a];
+               return typeof c === 'string' ? c :
+                   '\\u' + ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
+             }) + '"' :
+             '"' + string + '"';
+    }
+
+
+    function str(key, holder) {
+
+      // Produce a string from holder[key].
+
+      var i,          // The loop counter.
+          k,          // The member key.
+          v,          // The member value.
+          length,
+          mind = gap,
+          partial,
+          value = holder[key];
+
+      // If the value has a toJSON method, call it to obtain a replacement
+      // value.
+
+      if (value && typeof value === 'object' &&
+              typeof value.toJSON === 'function') {
+        value = value.toJSON(key);
+      }
+
+      // If we were called with a replacer function, then call the replacer to
+      // obtain a replacement value.
+
+      if (typeof rep === 'function') {
+        value = rep.call(holder, key, value);
+      }
+
+      // What happens next depends on the value's type.
+
+      switch (typeof value) {
+        case 'string':
+          return quote(value);
+
+        case 'number':
+          // JSON numbers must be finite. Encode non-finite numbers as null.
+          return isFinite(value) ? String(value) : 'null';
+
+        case 'boolean':
+        case 'null':
+          // If the value is a boolean or null, convert it to a string. Note:
+          // typeof null does not produce 'null'. The case is included here in
+          // the remote chance that this gets fixed someday.
+          return String(value);
+
+          // If the type is 'object', we might be dealing with an object or an
+          // array or null.
+
+        case 'object':
+
+          // Due to a specification blunder in ECMAScript, typeof null is
+          // 'object', so watch out for that case.
+
+          if (!value) {
+            return 'null';
+          }
+
+          // Make an array to hold the partial results of stringifying this
+          // object value.
+
+          gap += indent;
+          partial = [];
+
+          // Is the value an array?
+
+          if (Object.prototype.toString.apply(value) === '[object Array]') {
+
+            // The value is an array. Stringify every element. Use null as a
+            // placeholder for non-JSON values.
+
+            length = value.length;
+            for (i = 0; i < length; i += 1) {
+              partial[i] = str(i, value) || 'null';
+            }
+
+            // Join all of the elements together, separated with commas, and
+            // wrap them in brackets.
+
+            v = partial.length === 0 ? '[]' :
+                    gap ? '[\n' + gap +
+                            partial.join(',\n' + gap) + '\n' +
+                                mind + ']' :
+                          '[' + partial.join(',') + ']';
+            gap = mind;
+            return v;
+          }
+
+          // If the replacer is an array, use it to select the members to be
+          // stringified.
+
+          if (rep && typeof rep === 'object') {
+            length = rep.length;
+            for (i = 0; i < length; i += 1) {
+              k = rep[i];
+              if (typeof k === 'string') {
+                v = str(k, value);
+                if (v) {
+                  partial.push(quote(k) + (gap ? ': ' : ':') + v);
+                }
+              }
+            }
+          } else {
+
+            // Otherwise, iterate through all of the keys in the object.
+            for (k in value) {
+              if (Object.hasOwnProperty.call(value, k)) {
+                v = str(k, value);
+                if (v) {
+                  partial.push(quote(k) + (gap ? ': ' : ':') + v);
+                }
+              }
+            }
+          }
+
+          // Join all of the member texts together, separated with commas,
+          // and wrap them in braces.
+
+          v = partial.length === 0 ? '{}' :
+              gap ? '{\n' + gap + partial.join(',\n' + gap) + '\n' +
+                      mind + '}' : '{' + partial.join(',') + '}';
+          gap = mind;
+          return v;
+      }
+    }
+
+    // If the JSON object does not yet have a stringify method, give it one.
+
+    if (typeof cvox.ChromeVoxJSON.stringify !== 'function') {
+      cvox.ChromeVoxJSON.stringify = function(value, replacer, space) {
+
+        // The stringify method takes a value and an optional replacer, and an
+        // optional space parameter, and returns a JSON text. The replacer can
+        // be a function that can replace values, or an array of strings that
+        // will select the keys. A default replacer method can be provided. Use
+        // of the space parameter can produce text that is more easily readable.
+
+        var i;
+        gap = '';
+        indent = '';
+
+        // If the space parameter is a number, make an indent string containing
+        // that many spaces.
+
+        if (typeof space === 'number') {
+          for (i = 0; i < space; i += 1) {
+            indent += ' ';
+          }
+
+          // If the space parameter is a string, it will be used as the indent
+          // string.
+
+        } else if (typeof space === 'string') {
+          indent = space;
+        }
+
+        // If there is a replacer, it must be a function or an array.
+        // Otherwise, throw an error.
+
+        rep = replacer;
+        if (replacer && typeof replacer !== 'function' &&
+            (typeof replacer !== 'object' ||
+            typeof replacer.length !== 'number')) {
+          throw new Error('JSON.stringify');
+        }
+
+        // Make a fake root object containing our value under the key of ''.
+        // Return the result of stringifying the value.
+
+        return str('', {'': value});
+      };
+    }
+
+
+    // If the JSON object does not yet have a parse method, give it one.
+
+    if (typeof cvox.ChromeVoxJSON.parse !== 'function') {
+      cvox.ChromeVoxJSON.parse = function(text, reviver) {
+
+        // The parse method takes a text and an optional reviver function, and
+        // returns a JavaScript value if the text is a valid JSON text.
+
+        var j;
+
+        function walk(holder, key) {
+
+          // The walk method is used to recursively walk the resulting structure
+          // so that modifications can be made.
+
+          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);
+        }
+
+
+        // Parsing happens in four stages. In the first stage, we replace
+        // certain Unicode characters with escape sequences. JavaScript handles
+        // many characters incorrectly, either silently deleting them, or
+        // treating them as line endings.
+
+        text = String(text);
+        cx.lastIndex = 0;
+        if (cx.test(text)) {
+          text = text.replace(cx, function(a) {
+            return '\\u' +
+                ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
+          });
+        }
+
+        // In the second stage, we run the text against regular expressions that
+        // look for non-JSON patterns. We are especially concerned with '()' and
+        // 'new' because they can cause invocation, and '=' because it can cause
+        // mutation. But just to be safe, we want to reject all unexpected
+        // forms.
+        // We split the second stage into 4 regexp operations in order to work
+        // around crippling inefficiencies in IE's and Safari's regexp engines.
+        // First we replace the JSON backslash pairs with '@' (a non-JSON
+        // character). Second, we replace all simple value tokens with ']'
+        // characters. Third, we delete all open brackets that follow a colon or
+        // comma or that begin the text. Finally, we look to see that the
+        // remaining characters are only whitespace or ']' or ',' or ':' or '{'
+        // or '}'. If that is so, then the text is safe for eval.
+
+        if (/^[\],:{}\s]*$/.
+        test(text.replace(/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, '@').
+        replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']').
+        replace(/(?:^|:|,)(?:\s*\[)+/g, ''))) {
+
+          // In the third stage we use the eval function to compile the text
+          // into a JavaScript structure. The '{' operator is subject to a
+          // syntactic ambiguity in JavaScript: it can begin a block or an
+          // object literal. We wrap the text in parens to eliminate the
+          // ambiguity.
+
+          j = eval('(' + text + ')');
+
+          // In the optional fourth stage, we recursively walk the new
+          // structure, passing each name/value pair to a reviver function for
+          // possible transformation.
+          return typeof reviver === 'function' ? walk({'': j}, '') : j;
+        }
+
+        // If the text is not JSON parseable, then a SyntaxError is thrown.
+
+        throw new SyntaxError('JSON.parse');
+      };
+    }
+  }());
+}