summaryrefslogtreecommitdiffstats
path: root/base/json_writer.cc
blob: 20c533b255fe350ab5b07fc31ad9f6e3a6c85256 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
// Copyright (c) 2006-2008 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.

#include "base/json_writer.h"

#include "base/logging.h"
#include "base/string_util.h"
#include "base/values.h"
#include "base/string_escape.h"

const char kPrettyPrintLineEnding[] = "\r\n";

/* static */
void JSONWriter::Write(const Value* const node, bool pretty_print,
                       std::string* json) {
  json->clear();
  // Is there a better way to estimate the size of the output?
  json->reserve(1024);
  JSONWriter writer(pretty_print, json);
  writer.BuildJSONString(node, 0);
  if (pretty_print)
    json->append(kPrettyPrintLineEnding);
}

JSONWriter::JSONWriter(bool pretty_print, std::string* json)
    : json_string_(json),
      pretty_print_(pretty_print) {
  DCHECK(json);
}

void JSONWriter::BuildJSONString(const Value* const node, int depth) {
  switch(node->GetType()) {
    case Value::TYPE_NULL:
      json_string_->append("null");
      break;

    case Value::TYPE_BOOLEAN:
      {
        bool value;
        bool result = node->GetAsBoolean(&value);
        DCHECK(result);
        json_string_->append(value ? "true" : "false");
        break;
      }

    case Value::TYPE_INTEGER:
      {
        int value;
        bool result = node->GetAsInteger(&value);
        DCHECK(result);
        StringAppendF(json_string_, "%d", value);
        break;
      }

    case Value::TYPE_REAL:
      {
        double value;
        bool result = node->GetAsReal(&value);
        DCHECK(result);
        std::string real = DoubleToString(value);
        // Ensure that the number has a .0 if there's no decimal or 'e'.  This
        // makes sure that when we read the JSON back, it's interpreted as a
        // real rather than an int.
        if (real.find('.') == std::string::npos &&
            real.find('e') == std::string::npos &&
            real.find('E') == std::string::npos) {
          real.append(".0");
        }
        json_string_->append(real);
        break;
      }

    case Value::TYPE_STRING:
      {
        std::wstring value;
        bool result = node->GetAsString(&value);
        DCHECK(result);
        AppendQuotedString(value);
        break;
      }

    case Value::TYPE_LIST:
      {
        json_string_->append("[");
        if (pretty_print_)
          json_string_->append(" ");

        const ListValue* list = static_cast<const ListValue*>(node);
        for (size_t i = 0; i < list->GetSize(); ++i) {
          if (i != 0) {
            json_string_->append(",");
            if (pretty_print_)
              json_string_->append(" ");
          }

          Value* value = NULL;
          bool result = list->Get(i, &value);
          DCHECK(result);
          BuildJSONString(value, depth);
        }

        if (pretty_print_)
          json_string_->append(" ");
        json_string_->append("]");
        break;
      }

    case Value::TYPE_DICTIONARY:
      {
        json_string_->append("{");
        if (pretty_print_)
          json_string_->append(kPrettyPrintLineEnding);

        const DictionaryValue* dict =
          static_cast<const DictionaryValue*>(node);
        for (DictionaryValue::key_iterator key_itr = dict->begin_keys();
             key_itr != dict->end_keys();
             ++key_itr) {

          if (key_itr != dict->begin_keys()) {
            json_string_->append(",");
            if (pretty_print_)
              json_string_->append(kPrettyPrintLineEnding);
          }

          Value* value = NULL;
          bool result = dict->Get(*key_itr, &value);
          DCHECK(result);

          if (pretty_print_)
            IndentLine(depth + 1);
          AppendQuotedString(*key_itr);
          if (pretty_print_) {
            json_string_->append(": ");
          } else {
            json_string_->append(":");
          }
          BuildJSONString(value, depth + 1);
        }

        if (pretty_print_) {
          json_string_->append(kPrettyPrintLineEnding);
          IndentLine(depth);
          json_string_->append("}");
        } else {
          json_string_->append("}");
        }
        break;
      }

    default:
      // TODO(jhughes): handle TYPE_BINARY
      NOTREACHED() << "unknown json type";
  }
}

void JSONWriter::AppendQuotedString(const std::wstring& str) {
  string_escape::JavascriptDoubleQuote(WideToUTF16Hack(str), true,
                                       json_string_);
}

void JSONWriter::IndentLine(int depth) {
  // It may be faster to keep an indent string so we don't have to keep
  // reallocating.
  json_string_->append(std::string(depth * 3, ' '));
}