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63711510b6
... you are too slow and QJson API is so ugly. Now using this wonderful json lib: https://github.com/nlohmann/json Results in release mode (QJson tests are not shown but QJson was even slower than string concat). PASS : TestQgsJsonUtils::testExportAttributesJson(Use json) RESULT : TestQgsJsonUtils::testExportAttributesJson():"Use json": 0.0022 msecs per iteration (total: 75, iterations: 32768) PASS : TestQgsJsonUtils::testExportAttributesJson(Use old string concat) RESULT : TestQgsJsonUtils::testExportAttributesJson():"Use old string concat": 0.0032 msecs per iteration (total: 54, iterations: 16384) PASS : TestQgsJsonUtils::testExportFeatureJson(Use json) RESULT : TestQgsJsonUtils::testExportFeatureJson():"Use json": 0.011 msecs per iteration (total: 96, iterations: 8192) PASS : TestQgsJsonUtils::testExportFeatureJson(Use old string concat) RESULT : TestQgsJsonUtils::testExportFeatureJson():"Use old string concat": 0.015 msecs per iteration (total: 64, iterations: 4096) PASS : TestQgsJsonUtils::testExportGeomToJson(Use json) RESULT : TestQgsJsonUtils::testExportGeomToJson():"Use json": 0.76 msecs per iteration (total: 98, iterations: 128) PASS : TestQgsJsonUtils::testExportGeomToJson(Use old string concat) RESULT : TestQgsJsonUtils::testExportGeomToJson():"Use old string concat": 0.85 msecs per iteration (total: 55, iterations: 64) PASS : TestQgsJsonUtils::cleanupTestCase()
120 lines
2.9 KiB
C++
120 lines
2.9 KiB
C++
#pragma once
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#include <algorithm> // copy
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#include <cstddef> // size_t
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#include <ios> // streamsize
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#include <iterator> // back_inserter
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#include <memory> // shared_ptr, make_shared
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#include <ostream> // basic_ostream
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#include <string> // basic_string
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#include <vector> // vector
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namespace nlohmann
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{
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namespace detail
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{
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/// abstract output adapter interface
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template<typename CharType> struct output_adapter_protocol
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{
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virtual void write_character(CharType c) = 0;
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virtual void write_characters(const CharType* s, std::size_t length) = 0;
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virtual ~output_adapter_protocol() = default;
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};
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/// a type to simplify interfaces
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template<typename CharType>
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using output_adapter_t = std::shared_ptr<output_adapter_protocol<CharType>>;
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/// output adapter for byte vectors
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template<typename CharType>
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class output_vector_adapter : public output_adapter_protocol<CharType>
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{
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public:
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explicit output_vector_adapter(std::vector<CharType>& vec) noexcept
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: v(vec)
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{}
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void write_character(CharType c) override
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{
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v.push_back(c);
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}
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void write_characters(const CharType* s, std::size_t length) override
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{
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std::copy(s, s + length, std::back_inserter(v));
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}
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private:
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std::vector<CharType>& v;
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};
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/// output adapter for output streams
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template<typename CharType>
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class output_stream_adapter : public output_adapter_protocol<CharType>
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{
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public:
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explicit output_stream_adapter(std::basic_ostream<CharType>& s) noexcept
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: stream(s)
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{}
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void write_character(CharType c) override
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{
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stream.put(c);
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}
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void write_characters(const CharType* s, std::size_t length) override
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{
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stream.write(s, static_cast<std::streamsize>(length));
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}
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private:
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std::basic_ostream<CharType>& stream;
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};
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/// output adapter for basic_string
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template<typename CharType, typename StringType = std::basic_string<CharType>>
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class output_string_adapter : public output_adapter_protocol<CharType>
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{
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public:
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explicit output_string_adapter(StringType& s) noexcept
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: str(s)
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{}
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void write_character(CharType c) override
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{
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str.push_back(c);
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}
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void write_characters(const CharType* s, std::size_t length) override
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{
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str.append(s, length);
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}
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private:
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StringType& str;
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};
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template<typename CharType, typename StringType = std::basic_string<CharType>>
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class output_adapter
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{
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public:
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output_adapter(std::vector<CharType>& vec)
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: oa(std::make_shared<output_vector_adapter<CharType>>(vec)) {}
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output_adapter(std::basic_ostream<CharType>& s)
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: oa(std::make_shared<output_stream_adapter<CharType>>(s)) {}
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output_adapter(StringType& s)
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: oa(std::make_shared<output_string_adapter<CharType, StringType>>(s)) {}
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operator output_adapter_t<CharType>()
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{
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return oa;
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}
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private:
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output_adapter_t<CharType> oa = nullptr;
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};
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} // namespace detail
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} // namespace nlohmann
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