json_writer.h revision ddb351dbec246cf1fab5ec20d2d5520909041de1 
1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef BASE_JSON_JSON_WRITER_H_
6#define BASE_JSON_JSON_WRITER_H_
7#pragma once
8
9#include <string>
10
11#include "base/base_api.h"
12#include "base/basictypes.h"
13
14class Value;
15
16namespace base {
17
18class BASE_API JSONWriter {
19 public:
20  // Given a root node, generates a JSON string and puts it into |json|.
21  // If |pretty_print| is true, return a slightly nicer formated json string
22  // (pads with whitespace to help readability).  If |pretty_print| is false,
23  // we try to generate as compact a string as possible.
24  // TODO(tc): Should we generate json if it would be invalid json (e.g.,
25  // |node| is not a DictionaryValue/ListValue or if there are inf/-inf float
26  // values)?
27  static void Write(const Value* const node, bool pretty_print,
28                    std::string* json);
29
30  // Same as above, but has an option to not escape the string, preserving its
31  // UTF8 characters. It is useful if you can pass resulting string to the
32  // JSON parser in binary form (as UTF8).
33  static void WriteWithOptionalEscape(const Value* const node,
34                                      bool pretty_print,
35                                      bool escape,
36                                      std::string* json);
37
38  // A static, constant JSON string representing an empty array.  Useful
39  // for empty JSON argument passing.
40  static const char* kEmptyArray;
41
42 private:
43  JSONWriter(bool pretty_print, std::string* json);
44
45  // Called recursively to build the JSON string.  Whe completed, value is
46  // json_string_ will contain the JSON.
47  void BuildJSONString(const Value* const node, int depth, bool escape);
48
49  // Appends a quoted, escaped, version of (UTF-8) str to json_string_.
50  void AppendQuotedString(const std::string& str);
51
52  // Adds space to json_string_ for the indent level.
53  void IndentLine(int depth);
54
55  // Where we write JSON data as we generate it.
56  std::string* json_string_;
57
58  bool pretty_print_;
59
60  DISALLOW_COPY_AND_ASSIGN(JSONWriter);
61};
62
63}  // namespace base
64
65#endif  // BASE_JSON_JSON_WRITER_H_
66