base/json/json_writer.h

   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_WRITER_H_
   6 #define BASE_JSON_JSON_WRITER_H_
   7
   8 #include <string>
   9
  10 #include "base/base_export.h"
  11 #include "base/basictypes.h"
  12
  13 namespace base {
  14
  15 class Value;
  16
  17 class BASE_EXPORT JSONWriter {
  18  public:
  19   enum Options {
  20     // This option instructs the writer that if a Binary value is encountered,
  21     // the value (and key if within a dictionary) will be omitted from the
  22     // output, and success will be returned. Otherwise, if a binary value is
  23     // encountered, failure will be returned.
  24     OPTIONS_OMIT_BINARY_VALUES = 1 << 0,
  25
  26     // This option instructs the writer to write doubles that have no fractional
  27     // part as a normal integer (i.e., without using exponential notation
  28     // or appending a '.0') as long as the value is within the range of a
  29     // 64-bit int.
  30     OPTIONS_OMIT_DOUBLE_TYPE_PRESERVATION = 1 << 1,
  31
  32     // Return a slightly nicer formatted json string (pads with whitespace to
  33     // help with readability).
  34     OPTIONS_PRETTY_PRINT = 1 << 2,
  35   };
  36
  37   // Given a root node, generates a JSON string and puts it into |json|.
  38   // TODO(tc): Should we generate json if it would be invalid json (e.g.,
  39   // |node| is not a DictionaryValue/ListValue or if there are inf/-inf float
  40   // values)? Return true on success and false on failure.
  41   static bool Write(const Value& node, std::string* json);
  42
  43   // Same as above but with |options| which is a bunch of JSONWriter::Options
  44   // bitwise ORed together. Return true on success and false on failure.
  45   static bool WriteWithOptions(const Value& node,
  46                                int options,
  47                                std::string* json);
  48
  49  private:
  50   JSONWriter(int options, std::string* json);
  51
  52   // Called recursively to build the JSON string. When completed,
  53   // |json_string_| will contain the JSON.
  54   bool BuildJSONString(const Value& node, size_t depth);
  55
  56   // Adds space to json_string_ for the indent level.
  57   void IndentLine(size_t depth);
  58
  59   bool omit_binary_values_;
  60   bool omit_double_type_preservation_;
  61   bool pretty_print_;
  62
  63   // Where we write JSON data as we generate it.
  64   std::string* json_string_;
  65
  66   DISALLOW_COPY_AND_ASSIGN(JSONWriter);
  67 };
  68
  69 }  // namespace base
  70
  71 #endif  // BASE_JSON_JSON_WRITER_H_