Move json to lib/json/{json.dart, json_frog.dart}

frog/lib/json_frog.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-#library('json');
-#import('dart:coreimpl');
-
-// TODO(jmesserly): this needs cleanup
-// Ideally JS objects could be treated as Dart Maps directly, and then we can
-// really use native JSON.parse and JSON.stringify.
-
-typedef Object _NativeJsonConvert(Object key, Object value);
-
-class _JSON native 'JSON' {
-  static Object parse(String jsonString, _NativeJsonConvert fn) native;
-  static String stringify(Object value, _NativeJsonConvert fn) native;
-}
-
-
-Object _getValue(obj, key) native 'return obj[key]';
-void _setValue(obj, key, value) native 'obj[key] = value';
-
-// This is a guard against general Dart objects getting through to
-// JSON.stringify. We restrict to JS primitives and JS Array.
-bool _directToJson(obj) native
-  "return typeof obj != 'object' || obj == null || obj instanceof Array";
-
-ListFactory<String> _jsKeys(Object obj) native '''
-if (obj != null && typeof obj == 'object' && !(obj instanceof Array)) {
-return Object.keys(obj);
-}
-return null;
-''';
-
-/**
- * Dart interface to JavaScript objects and JSON.
- */
-class JSON {
-  /**
-   * Takes a string in JSON notation and returns the value it
-   * represents.  The resulting value is one of the following:
-   *   null
-   *   a bool
-   *   a double
-   *   a String
-   *   an Array of values (recursively)
-   *   a Map from property names to values (recursively)
-   */
-  static Object parse(String str) {
-    return _JSON.parse(str, (_, obj) {
-      final keys = _jsKeys(obj);
-      if (keys == null) return obj;
-
-      // Note: only need to shallow convert here--JSON.parse handles the rest.
-      final map = {};
-      for (String key in keys) {
-        map[key] = _getValue(obj, key);
-      }
-      return map;
-    });
-  }
-
-  /**
-   * Takes a value and returns a string in JSON notation
-   * representing its value, or returns null if the value is not representable
-   * in JSON.  A representable value is one of the following:
-   *   null
-   *   a bool
-   *   a double
-   *   a String
-   *   an Array of values (recursively)
-   *   a Map from property names to values (recursively)
-   */
-  // TODO(jmesserly): handle any List subtype? Right now it's converted as
-  // something like:
-  //     {"0":1,"1":2}
-  static String stringify(Object value) {
-    return _JSON.stringify(value, (_, obj) {
-      if (_directToJson(obj)) return obj;
-      if (obj is Map<String, Dynamic>) {
-        Map<String, Dynamic> map = obj;
-        obj = new Object();
-        map.forEach((k, v) => _setValue(obj, k, v));
-        return obj;
-      }
-      throw new IllegalArgumentException('cannot convert "$value" to JSON');
-    });
-  }
-}