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

1 files changed, 297 insertions, 0 deletions

diff --git a/src/proj_json_streaming_writer.cpp b/src/proj_json_streaming_writer.cpp
new file mode 100644
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--- /dev/null
+++ b/src/proj_json_streaming_writer.cpp
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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.
+ ****************************************************************************/
+
+/*! @cond Doxygen_Suppress */
+
+#include <vector>
+#include <string>
+
+#include "proj_json_streaming_writer.hpp"
+
+#include <string.h>
+#include <sqlite3.h>
+#include <stdarg.h>
+#include <cmath>
+#define CPLAssert(x) do {} while(0)
+#define CPLIsNan     std::isnan
+#define CPLIsInf     std::isinf
+#define CPL_FRMT_GIB  "%lld"
+#define CPL_FRMT_GUIB "%llu"
+typedef std::uint64_t GUIntBig;
+
+static std::string CPLSPrintf(const char* fmt, ...)
+{
+    std::string res;
+    res.resize(256);
+    va_list list;
+    va_start(list, fmt);
+    sqlite3_vsnprintf(256, &res[0], fmt, list);
+    va_end(list);
+    res.resize(strlen(&res[0]));
+    return res;
+}
+
+namespace PROJ
+{
+
+CPLJSonStreamingWriter::CPLJSonStreamingWriter(
+                    SerializationFuncType pfnSerializationFunc,
+                    void* pUserData):
+    m_pfnSerializationFunc(pfnSerializationFunc),
+    m_pUserData(pUserData)
+{}
+
+CPLJSonStreamingWriter::~CPLJSonStreamingWriter()
+{
+    CPLAssert( m_nLevel == 0 );
+    CPLAssert( m_states.empty() );
+}
+
+void CPLJSonStreamingWriter::Print(const std::string& text)
+{
+    if( m_pfnSerializationFunc )
+    {
+        m_pfnSerializationFunc(text.c_str(), m_pUserData);
+    }
+    else
+    {
+        m_osStr += text;
+    }
+}
+
+void CPLJSonStreamingWriter::SetIndentationSize(int nSpaces)
+{
+    CPLAssert( m_nLevel == 0 );
+    m_osIndent.clear();
+    m_osIndent.resize(nSpaces, ' ');
+}
+
+void CPLJSonStreamingWriter::IncIndent()
+{
+    m_nLevel ++;
+    if( m_bPretty )
+        m_osIndentAcc += m_osIndent;
+}
+
+void CPLJSonStreamingWriter::DecIndent()
+{
+    CPLAssert(m_nLevel > 0);
+    m_nLevel --;
+    if( m_bPretty )
+        m_osIndentAcc.resize(m_osIndentAcc.size() - m_osIndent.size());
+}
+
+std::string CPLJSonStreamingWriter::FormatString(const std::string& str)
+{
+    std::string ret;
+    ret += '"';
+    for( char ch: str )
+    {
+        switch(ch)
+        {
+            case '"' : ret += "\\\""; break;
+            case '\\': ret += "\\\\"; break;
+            case '\b': ret += "\\b";  break;
+            case '\f': ret += "\\f";  break;
+            case '\n': ret += "\\n";  break;
+            case '\r': ret += "\\r";  break;
+            case '\t': ret += "\\t";  break;
+            default: 
+                if( static_cast<unsigned char>(ch) < ' ' )
+                    ret += CPLSPrintf("\\u%04X", ch);
+                else
+                    ret += ch;
+                break;
+        }
+    }
+    ret += '"';
+    return ret;
+}
+
+void CPLJSonStreamingWriter::EmitCommaIfNeeded()
+{
+    if( m_bWaitForValue )
+    {
+        m_bWaitForValue = false;
+    }
+    else if( !m_states.empty() )
+    {
+        if( !m_states.back().bFirstChild )
+        {
+            Print(",");
+            if( m_bPretty && !m_bNewLineEnabled )
+                Print(" ");
+        }
+        if( m_bPretty && m_bNewLineEnabled )
+        {
+            Print("\n");
+            Print(m_osIndentAcc);
+        }
+        m_states.back().bFirstChild = false;
+    }
+}
+
+void CPLJSonStreamingWriter::StartObj()
+{
+    EmitCommaIfNeeded();
+    Print("{");
+    IncIndent();
+    m_states.emplace_back(State(true));
+}
+
+void CPLJSonStreamingWriter::EndObj()
+{
+    CPLAssert(!m_bWaitForValue);
+    CPLAssert( !m_states.empty() );
+    CPLAssert( m_states.back().bIsObj );
+    DecIndent();
+    if( !m_states.back().bFirstChild )
+    {
+        if( m_bPretty && m_bNewLineEnabled )
+        {
+            Print("\n");
+            Print(m_osIndentAcc);
+        }
+    }
+    m_states.pop_back();
+    Print("}");
+}
+
+void CPLJSonStreamingWriter::StartArray()
+{
+    EmitCommaIfNeeded();
+    Print("[");
+    IncIndent();
+    m_states.emplace_back(State(false));
+}
+
+void CPLJSonStreamingWriter::EndArray()
+{
+    CPLAssert( !m_states.empty() );
+    CPLAssert( !m_states.back().bIsObj );
+    DecIndent();
+    if( !m_states.back().bFirstChild )
+    {
+        if( m_bPretty && m_bNewLineEnabled )
+        {
+            Print("\n");
+            Print(m_osIndentAcc);
+        }
+    }
+    m_states.pop_back();
+    Print("]");
+}
+
+void CPLJSonStreamingWriter::AddObjKey(const std::string& key)
+{
+    CPLAssert( !m_states.empty() );
+    CPLAssert( m_states.back().bIsObj );
+    CPLAssert(!m_bWaitForValue);
+    EmitCommaIfNeeded();
+    Print(FormatString(key));
+    Print(m_bPretty ? ": " : ":");
+    m_bWaitForValue = true;
+}
+
+void CPLJSonStreamingWriter::Add(bool bVal)
+{
+    EmitCommaIfNeeded();
+    Print(bVal ? "true" : "false");
+}
+
+void CPLJSonStreamingWriter::Add(const std::string& str)
+{
+    EmitCommaIfNeeded();
+    Print(FormatString(str));
+}
+
+void CPLJSonStreamingWriter::Add(const char* pszStr)
+{
+    EmitCommaIfNeeded();
+    Print(FormatString(pszStr));
+}
+
+void CPLJSonStreamingWriter::Add(GIntBig nVal)
+{
+    EmitCommaIfNeeded();
+    Print(CPLSPrintf(CPL_FRMT_GIB, nVal));
+}
+
+void CPLJSonStreamingWriter::Add(GUInt64 nVal)
+{
+    EmitCommaIfNeeded();
+    Print(CPLSPrintf(CPL_FRMT_GUIB, static_cast<GUIntBig>(nVal)));
+}
+
+void CPLJSonStreamingWriter::Add(float fVal, int nPrecision)
+{
+    EmitCommaIfNeeded();
+    if( CPLIsNan(fVal) )
+    {
+        Print("\"NaN\"");
+    }
+    else if( CPLIsInf(fVal) )
+    {
+        Print( fVal > 0 ? "\"Infinity\"" : "\"-Infinity\"" );
+    }
+    else
+    {
+        char szFormatting[10];
+        snprintf(szFormatting, sizeof(szFormatting), "%%.%dg", nPrecision);
+        Print(CPLSPrintf(szFormatting, fVal));
+    }
+}
+
+void CPLJSonStreamingWriter::Add(double dfVal, int nPrecision)
+{
+    EmitCommaIfNeeded();
+    if( CPLIsNan(dfVal) )
+    {
+       Print("\"NaN\"");
+    }
+    else if( CPLIsInf(dfVal) )
+    {
+        Print( dfVal > 0 ? "\"Infinity\"" : "\"-Infinity\"" );
+    }
+    else
+    {
+        char szFormatting[10];
+        snprintf(szFormatting, sizeof(szFormatting), "%%.%dg", nPrecision);
+        Print(CPLSPrintf(szFormatting, dfVal));
+    }
+}
+
+void CPLJSonStreamingWriter::AddNull()
+{
+    EmitCommaIfNeeded();
+    Print("null");
+}
+
+} // namespace PROJ
+
+/*! @endcond */