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  }
65  };
66  std::vector<State> m_states{};
67  bool m_bWaitForValue = false;
68 
69  void Print(const std::string &text);
70  void IncIndent();
71  void DecIndent();
72  static std::string FormatString(const std::string &str);
73  void EmitCommaIfNeeded();
74 
75  public:
76  CPLJSonStreamingWriter(SerializationFuncType pfnSerializationFunc,
77  void *pUserData);
78  ~CPLJSonStreamingWriter();
79 
80  void SetPrettyFormatting(bool bPretty)
81  {
82  m_bPretty = bPretty;
83  }
84  void SetIndentationSize(int nSpaces);
85 
86  // cppcheck-suppress functionStatic
87  const std::string &GetString() const
88  {
89  return m_osStr;
90  }
91 
92  void Add(const std::string &str);
93  void Add(const char *pszStr);
94  void Add(bool bVal);
95  void Add(int nVal)
96  {
97  Add(static_cast<std::int64_t>(nVal));
98  }
99  void Add(unsigned int nVal)
100  {
101  Add(static_cast<std::int64_t>(nVal));
102  }
103  void Add(std::int64_t nVal);
104  void Add(std::uint64_t nVal);
105  void Add(float fVal, int nPrecision = 9);
106  void Add(double dfVal, int nPrecision = 18);
107  void AddNull();
108 
109  void StartObj();
110  void EndObj();
111  void AddObjKey(const std::string &key);
112  struct CPL_DLL ObjectContext
113  {
114  CPLJSonStreamingWriter &m_serializer;
115 
116  ObjectContext(const ObjectContext &) = delete;
117  ObjectContext(ObjectContext &&) = default;
118 
119  explicit inline ObjectContext(CPLJSonStreamingWriter &serializer)
120  : m_serializer(serializer)
121  {
122  m_serializer.StartObj();
123  }
124  ~ObjectContext()
125  {
126  m_serializer.EndObj();
127  }
128  };
129  inline ObjectContext MakeObjectContext()
130  {
131  return ObjectContext(*this);
132  }
133 
134  void StartArray();
135  void EndArray();
136  struct CPL_DLL ArrayContext
137  {
138  CPLJSonStreamingWriter &m_serializer;
139  bool m_bForceSingleLine;
140  bool m_bNewLineEnabledBackup;
141 
142  ArrayContext(const ArrayContext &) = delete;
143  ArrayContext(ArrayContext &&) = default;
144 
145  inline explicit ArrayContext(CPLJSonStreamingWriter &serializer,
146  bool bForceSingleLine = false)
147  : m_serializer(serializer), m_bForceSingleLine(bForceSingleLine),
148  m_bNewLineEnabledBackup(serializer.GetNewLine())
149  {
150  if (m_bForceSingleLine)
151  serializer.SetNewline(false);
152  m_serializer.StartArray();
153  }
154  ~ArrayContext()
155  {
156  m_serializer.EndArray();
157  if (m_bForceSingleLine)
158  m_serializer.SetNewline(m_bNewLineEnabledBackup);
159  }
160  };
161  inline ArrayContext MakeArrayContext(bool bForceSingleLine = false)
162  {
163  return ArrayContext(*this, bForceSingleLine);
164  }
165 
166  bool GetNewLine() const
167  {
168  return m_bNewLineEnabled;
169  }
170  void SetNewline(bool bEnabled)
171  {
172  m_bNewLineEnabled = bEnabled;
173  }
174 };
175 
176 #endif // __cplusplus
177 
180 #endif // CPL_JSON_STREAMING_WRITER_H
cpl_port.h