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