1// Copyright (c) 2012 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_FILE_VALUE_SERIALIZER_H_
6#define BASE_JSON_JSON_FILE_VALUE_SERIALIZER_H_
7
8#include <string>
9
10#include "base/base_export.h"
11#include "base/basictypes.h"
12#include "base/files/file_path.h"
13#include "base/values.h"
14
15class BASE_EXPORT JSONFileValueSerializer : public base::ValueSerializer {
16 public:
17  // json_file_patch is the path of a file that will be source of the
18  // deserialization or the destination of the serialization.
19  // When deserializing, the file should exist, but when serializing, the
20  // serializer will attempt to create the file at the specified location.
21  explicit JSONFileValueSerializer(const base::FilePath& json_file_path)
22    : json_file_path_(json_file_path),
23      allow_trailing_comma_(false) {}
24
25  virtual ~JSONFileValueSerializer() {}
26
27  // DO NOT USE except in unit tests to verify the file was written properly.
28  // We should never serialize directly to a file since this will block the
29  // thread. Instead, serialize to a string and write to the file you want on
30  // the file thread.
31  //
32  // Attempt to serialize the data structure represented by Value into
33  // JSON.  If the return value is true, the result will have been written
34  // into the file whose name was passed into the constructor.
35  virtual bool Serialize(const base::Value& root) OVERRIDE;
36
37  // Equivalent to Serialize(root) except binary values are omitted from the
38  // output.
39  bool SerializeAndOmitBinaryValues(const base::Value& root);
40
41  // Attempt to deserialize the data structure encoded in the file passed
42  // in to the constructor into a structure of Value objects.  If the return
43  // value is NULL, and if |error_code| is non-null, |error_code| will
44  // contain an integer error code (either JsonFileError or JsonParseError).
45  // If |error_message| is non-null, it will be filled in with a formatted
46  // error message including the location of the error if appropriate.
47  // The caller takes ownership of the returned value.
48  virtual base::Value* Deserialize(int* error_code,
49                                   std::string* error_message) OVERRIDE;
50
51  // This enum is designed to safely overlap with JSONReader::JsonParseError.
52  enum JsonFileError {
53    JSON_NO_ERROR = 0,
54    JSON_ACCESS_DENIED = 1000,
55    JSON_CANNOT_READ_FILE,
56    JSON_FILE_LOCKED,
57    JSON_NO_SUCH_FILE
58  };
59
60  // File-specific error messages that can be returned.
61  static const char* kAccessDenied;
62  static const char* kCannotReadFile;
63  static const char* kFileLocked;
64  static const char* kNoSuchFile;
65
66  // Convert an error code into an error message.  |error_code| is assumed to
67  // be a JsonFileError.
68  static const char* GetErrorMessageForCode(int error_code);
69
70  void set_allow_trailing_comma(bool new_value) {
71    allow_trailing_comma_ = new_value;
72  }
73
74 private:
75  bool SerializeInternal(const base::Value& root, bool omit_binary_values);
76
77  base::FilePath json_file_path_;
78  bool allow_trailing_comma_;
79
80  // A wrapper for ReadFileToString which returns a non-zero JsonFileError if
81  // there were file errors.
82  int ReadFileToString(std::string* json_string);
83
84  DISALLOW_IMPLICIT_CONSTRUCTORS(JSONFileValueSerializer);
85};
86
87#endif  // BASE_JSON_JSON_FILE_VALUE_SERIALIZER_H_
88
89