Proof-of-concept of JSON export limited to PrimeMeridian (refs #1545)

1 files changed, 145 insertions, 0 deletions

diff --git a/src/proj_json_streaming_writer.hpp b/src/proj_json_streaming_writer.hpp
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+/******************************************************************************
+ *
+ * Project:  CPL - Common Portability Library
+ * Purpose:  JSon streaming writer
+ * Author:   Even Rouault, even.rouault at spatialys.com
+ *
+ ******************************************************************************
+ * Copyright (c) 2019, Even Rouault <even.rouault at spatialys.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ ****************************************************************************/
+
+#ifndef PROJ_JSON_STREAMING_WRITER_H
+#define PROJ_JSON_STREAMING_WRITER_H
+
+/*! @cond Doxygen_Suppress */
+
+#include <vector>
+#include <string>
+
+#define CPL_DLL
+
+namespace PROJ
+{
+
+typedef std::int64_t GIntBig;
+typedef std::uint64_t GUInt64;
+
+class CPL_DLL CPLJSonStreamingWriter
+{
+public:
+    typedef void (*SerializationFuncType)(const char* pszTxt, void* pUserData);
+
+private:
+    CPLJSonStreamingWriter(const CPLJSonStreamingWriter&) = delete;
+    CPLJSonStreamingWriter& operator=(const CPLJSonStreamingWriter&) = delete;
+
+    std::string m_osStr{};
+    SerializationFuncType m_pfnSerializationFunc = nullptr;
+    void* m_pUserData = nullptr;
+    bool m_bPretty = true;
+    std::string m_osIndent = std::string("  ");
+    std::string m_osIndentAcc{};
+    int m_nLevel = 0;
+    bool m_bNewLineEnabled = true;
+    struct State
+    {
+        bool bIsObj = false;
+        bool bFirstChild = true;
+        explicit State(bool bIsObjIn): bIsObj(bIsObjIn) {}
+    };
+    std::vector<State> m_states{};
+    bool m_bWaitForValue = false;
+
+    void Print(const std::string& text);
+    void IncIndent();
+    void DecIndent();
+    static std::string FormatString(const std::string& str);
+    void EmitCommaIfNeeded();
+
+public:
+    CPLJSonStreamingWriter(SerializationFuncType pfnSerializationFunc,
+                           void* pUserData);
+    ~CPLJSonStreamingWriter();
+
+    void SetPrettyFormatting(bool bPretty) { m_bPretty = bPretty; }
+    void SetIndentationSize(int nSpaces);
+
+    // cppcheck-suppress functionStatic
+    const std::string& GetString() const { return m_osStr; }
+
+    void Add(const std::string& str);
+    void Add(const char* pszStr);
+    void Add(bool bVal);
+    void Add(int nVal) { Add(static_cast<GIntBig>(nVal)); }
+    void Add(unsigned int nVal) { Add(static_cast<GIntBig>(nVal)); }
+    void Add(GIntBig nVal);
+    void Add(GUInt64 nVal);
+    void Add(float fVal, int nPrecision = 9);
+    void Add(double dfVal, int nPrecision = 18);
+    void AddNull();
+
+    void StartObj();
+    void EndObj();
+    void AddObjKey(const std::string& key);
+    struct CPL_DLL ObjectContext
+    {
+        CPLJSonStreamingWriter& m_serializer;
+        explicit ObjectContext(CPLJSonStreamingWriter& serializer):
+            m_serializer(serializer) { m_serializer.StartObj(); }
+        ~ObjectContext() { m_serializer.EndObj(); }
+    };
+
+    void StartArray();
+    void EndArray();
+    struct CPL_DLL ArrayContext
+    {
+        CPLJSonStreamingWriter& m_serializer;
+        bool m_bForceSingleLine;
+        bool m_bNewLineEnabledBackup;
+
+        ArrayContext(CPLJSonStreamingWriter& serializer,
+                     bool bForceSingleLine = false):
+            m_serializer(serializer),
+            m_bForceSingleLine(bForceSingleLine),
+            m_bNewLineEnabledBackup(serializer.GetNewLine())
+        {
+            if( m_bForceSingleLine )
+                serializer.SetNewline(false);
+            m_serializer.StartArray();
+
+        }
+        ~ArrayContext()
+        {
+            m_serializer.EndArray();
+            if( m_bForceSingleLine )
+                m_serializer.SetNewline(m_bNewLineEnabledBackup);
+        }
+    };
+
+    bool GetNewLine() const { return m_bNewLineEnabled; }
+    void SetNewline(bool bEnabled) { m_bNewLineEnabled = bEnabled; }
+};
+
+} // namespace PROJ
+
+/*! @endcond */
+
+#endif // PROJ_JSON_STREAMING_WRITER_H