GDAL
cpl_json_streaming_writer.h
1 /******************************************************************************
2  *
3  * Project: CPL - Common Portability Library
4  * Purpose: JSon streaming writer
5  * Author: Even Rouault, even.rouault at spatialys.com
6  *
7  ******************************************************************************
8  * Copyright (c) 2019, Even Rouault <even.rouault at spatialys.com>
9  *
10  * Permission is hereby granted, free of charge, to any person obtaining a
11  * copy of this software and associated documentation files (the "Software"),
12  * to deal in the Software without restriction, including without limitation
13  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
14  * and/or sell copies of the Software, and to permit persons to whom the
15  * Software is furnished to do so, subject to the following conditions:
16  *
17  * The above copyright notice and this permission notice shall be included
18  * in all copies or substantial portions of the Software.
19  *
20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
21  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
23  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
25  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
26  * DEALINGS IN THE SOFTWARE.
27  ****************************************************************************/
28 
29 #ifndef CPL_JSON_STREAMING_WRITER_H
30 #define CPL_JSON_STREAMING_WRITER_H
31 
34 #if defined(__cplusplus) && !defined(CPL_SUPRESS_CPLUSPLUS)
35 
36 #include <cstdint>
37 #include <vector>
38 #include <string>
39 #include "cpl_port.h"
40 
41 class CPL_DLL CPLJSonStreamingWriter
42 {
43 public:
44  typedef void (*SerializationFuncType)(const char* pszTxt, void* pUserData);
45 
46 private:
47  CPLJSonStreamingWriter(const CPLJSonStreamingWriter&) = delete;
48  CPLJSonStreamingWriter& operator=(const CPLJSonStreamingWriter&) = delete;
49 
50  std::string m_osStr{};
51  SerializationFuncType m_pfnSerializationFunc = nullptr;
52  void* m_pUserData = nullptr;
53  bool m_bPretty = true;
54  std::string m_osIndent = std::string(" ");
55  std::string m_osIndentAcc{};
56  int m_nLevel = 0;
57  bool m_bNewLineEnabled = true;
58  struct State
59  {
60  bool bIsObj = false;
61  bool bFirstChild = true;
62  explicit State(bool bIsObjIn): bIsObj(bIsObjIn) {}
63  };
64  std::vector<State> m_states{};
65  bool m_bWaitForValue = false;
66 
67  void Print(const std::string& text);
68  void IncIndent();
69  void DecIndent();
70  static std::string FormatString(const std::string& str);
71  void EmitCommaIfNeeded();
72 
73 public:
74  CPLJSonStreamingWriter(SerializationFuncType pfnSerializationFunc,
75  void* pUserData);
76  ~CPLJSonStreamingWriter();
77 
78  void SetPrettyFormatting(bool bPretty) { m_bPretty = bPretty; }
79  void SetIndentationSize(int nSpaces);
80 
81  // cppcheck-suppress functionStatic
82  const std::string& GetString() const { return m_osStr; }
83 
84  void Add(const std::string& str);
85  void Add(const char* pszStr);
86  void Add(bool bVal);
87  void Add(int nVal) { Add(static_cast<std::int64_t>(nVal)); }
88  void Add(unsigned int nVal) { Add(static_cast<std::int64_t>(nVal)); }
89  void Add(std::int64_t nVal);
90  void Add(std::uint64_t nVal);
91  void Add(float fVal, int nPrecision = 9);
92  void Add(double dfVal, int nPrecision = 18);
93  void AddNull();
94 
95  void StartObj();
96  void EndObj();
97  void AddObjKey(const std::string& key);
98  struct CPL_DLL ObjectContext
99  {
100  CPLJSonStreamingWriter& m_serializer;
101 
102  ObjectContext(const ObjectContext &) = delete;
103  ObjectContext(ObjectContext&&) = default;
104 
105  explicit inline ObjectContext(CPLJSonStreamingWriter& serializer):
106  m_serializer(serializer) { m_serializer.StartObj(); }
107  ~ObjectContext() { m_serializer.EndObj(); }
108  };
109  inline ObjectContext MakeObjectContext() { return ObjectContext(*this); }
110 
111  void StartArray();
112  void EndArray();
113  struct CPL_DLL ArrayContext
114  {
115  CPLJSonStreamingWriter& m_serializer;
116  bool m_bForceSingleLine;
117  bool m_bNewLineEnabledBackup;
118 
119  ArrayContext(const ArrayContext &) = delete;
120  ArrayContext(ArrayContext&&) = default;
121 
122  inline explicit ArrayContext(CPLJSonStreamingWriter& serializer,
123  bool bForceSingleLine = false):
124  m_serializer(serializer),
125  m_bForceSingleLine(bForceSingleLine),
126  m_bNewLineEnabledBackup(serializer.GetNewLine())
127  {
128  if( m_bForceSingleLine )
129  serializer.SetNewline(false);
130  m_serializer.StartArray();
131 
132  }
133  ~ArrayContext()
134  {
135  m_serializer.EndArray();
136  if( m_bForceSingleLine )
137  m_serializer.SetNewline(m_bNewLineEnabledBackup);
138  }
139  };
140  inline ArrayContext MakeArrayContext(bool bForceSingleLine = false)
141  { return ArrayContext(*this, bForceSingleLine); }
142 
143  bool GetNewLine() const { return m_bNewLineEnabled; }
144  void SetNewline(bool bEnabled) { m_bNewLineEnabled = bEnabled; }
145 };
146 
147 #endif // __cplusplus
148 
151 #endif // CPL_JSON_STREAMING_WRITER_H
cpl_port.h