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      1 // Protocol Buffers - Google's data interchange format
      2 // Copyright 2008 Google Inc.  All rights reserved.
      3 // https://developers.google.com/protocol-buffers/
      4 //
      5 // Redistribution and use in source and binary forms, with or without
      6 // modification, are permitted provided that the following conditions are
      7 // met:
      8 //
      9 //     * Redistributions of source code must retain the above copyright
     10 // notice, this list of conditions and the following disclaimer.
     11 //     * Redistributions in binary form must reproduce the above
     12 // copyright notice, this list of conditions and the following disclaimer
     13 // in the documentation and/or other materials provided with the
     14 // distribution.
     15 //     * Neither the name of Google Inc. nor the names of its
     16 // contributors may be used to endorse or promote products derived from
     17 // this software without specific prior written permission.
     18 //
     19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     23 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30 
     31 #ifndef GOOGLE_PROTOBUF_UTIL_CONVERTER_OBJECT_WRITER_H__
     32 #define GOOGLE_PROTOBUF_UTIL_CONVERTER_OBJECT_WRITER_H__
     33 
     34 #include <google/protobuf/stubs/common.h>
     35 #include <google/protobuf/stubs/stringpiece.h>
     36 
     37 namespace google {
     38 namespace protobuf {
     39 namespace util {
     40 namespace converter {
     41 
     42 class DataPiece;
     43 
     44 // An ObjectWriter is an interface for writing a stream of events
     45 // representing objects and collections. Implementation of this
     46 // interface can be used to write an object stream to an in-memory
     47 // structure, protobufs, JSON, XML, or any other output format
     48 // desired. The ObjectSource interface is typically used as the
     49 // source of an object stream.
     50 //
     51 // See JsonObjectWriter for a sample implementation of ObjectWriter
     52 // and its use.
     53 //
     54 // Derived classes could be thread-unsafe.
     55 //
     56 // TODO(xinb): seems like a prime candidate to apply the RAII paradigm
     57 // and get rid the need to call EndXXX().
     58 class LIBPROTOBUF_EXPORT ObjectWriter {
     59  public:
     60   virtual ~ObjectWriter() {}
     61 
     62   // Starts an object. If the name is empty, the object will not be named.
     63   virtual ObjectWriter* StartObject(StringPiece name) = 0;
     64 
     65   // Ends an object.
     66   virtual ObjectWriter* EndObject() = 0;
     67 
     68   // Starts a list. If the name is empty, the list will not be named.
     69   virtual ObjectWriter* StartList(StringPiece name) = 0;
     70 
     71   // Ends a list.
     72   virtual ObjectWriter* EndList() = 0;
     73 
     74   // Renders a boolean value.
     75   virtual ObjectWriter* RenderBool(StringPiece name, bool value) = 0;
     76 
     77   // Renders an 32-bit integer value.
     78   virtual ObjectWriter* RenderInt32(StringPiece name, int32 value) = 0;
     79 
     80   // Renders an 32-bit unsigned integer value.
     81   virtual ObjectWriter* RenderUint32(StringPiece name, uint32 value) = 0;
     82 
     83   // Renders a 64-bit integer value.
     84   virtual ObjectWriter* RenderInt64(StringPiece name, int64 value) = 0;
     85 
     86   // Renders an 64-bit unsigned integer value.
     87   virtual ObjectWriter* RenderUint64(StringPiece name, uint64 value) = 0;
     88 
     89   // Renders a double value.
     90   virtual ObjectWriter* RenderDouble(StringPiece name, double value) = 0;
     91 
     92   // Renders a float value.
     93   virtual ObjectWriter* RenderFloat(StringPiece name, float value) = 0;
     94 
     95   // Renders a StringPiece value. This is for rendering strings.
     96   virtual ObjectWriter* RenderString(StringPiece name, StringPiece value) = 0;
     97 
     98   // Renders a bytes value.
     99   virtual ObjectWriter* RenderBytes(StringPiece name, StringPiece value) = 0;
    100 
    101   // Renders a Null value.
    102   virtual ObjectWriter* RenderNull(StringPiece name) = 0;
    103 
    104   // Renders a DataPiece object to a ObjectWriter.
    105   static void RenderDataPieceTo(const DataPiece& data, StringPiece name,
    106                                 ObjectWriter* ow);
    107 
    108   // Indicates whether this ObjectWriter has completed writing the root message,
    109   // usually this means writing of one complete object. Subclasses must override
    110   // this behavior appropriately.
    111   virtual bool done() { return false; }
    112 
    113   void set_use_strict_base64_decoding(bool value) {
    114     use_strict_base64_decoding_ = value;
    115   }
    116 
    117   bool use_strict_base64_decoding() const {
    118     return use_strict_base64_decoding_;
    119   }
    120 
    121  protected:
    122   ObjectWriter() : use_strict_base64_decoding_(true) {}
    123 
    124  private:
    125   // If set to true, we use the stricter version of base64 decoding for byte
    126   // fields by making sure decoded version encodes back to the original string.
    127   bool use_strict_base64_decoding_;
    128 
    129   // Do not add any data members to this class.
    130   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ObjectWriter);
    131 };
    132 
    133 }  // namespace converter
    134 }  // namespace util
    135 }  // namespace protobuf
    136 
    137 }  // namespace google
    138 #endif  // GOOGLE_PROTOBUF_UTIL_CONVERTER_OBJECT_WRITER_H__
    139