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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
3.4 KiB
C++
120 lines
3.4 KiB
C++
#pragma once
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#include <cstddef> // ptrdiff_t
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#include <iterator> // reverse_iterator
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#include <utility> // declval
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namespace nlohmann
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{
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namespace detail
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{
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//////////////////////
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// reverse_iterator //
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//////////////////////
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/*!
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@brief a template for a reverse iterator class
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@tparam Base the base iterator type to reverse. Valid types are @ref
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iterator (to create @ref reverse_iterator) and @ref const_iterator (to
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create @ref const_reverse_iterator).
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@requirement The class satisfies the following concept requirements:
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-
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[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
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The iterator that can be moved can be moved in both directions (i.e.
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incremented and decremented).
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- [OutputIterator](https://en.cppreference.com/w/cpp/named_req/OutputIterator):
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It is possible to write to the pointed-to element (only if @a Base is
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@ref iterator).
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@since version 1.0.0
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*/
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template<typename Base>
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class json_reverse_iterator : public std::reverse_iterator<Base>
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{
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public:
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using difference_type = std::ptrdiff_t;
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/// shortcut to the reverse iterator adapter
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using base_iterator = std::reverse_iterator<Base>;
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/// the reference type for the pointed-to element
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using reference = typename Base::reference;
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/// create reverse iterator from iterator
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explicit json_reverse_iterator(const typename base_iterator::iterator_type& it) noexcept
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: base_iterator(it) {}
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/// create reverse iterator from base class
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explicit json_reverse_iterator(const base_iterator& it) noexcept : base_iterator(it) {}
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/// post-increment (it++)
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json_reverse_iterator const operator++(int)
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{
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return static_cast<json_reverse_iterator>(base_iterator::operator++(1));
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}
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/// pre-increment (++it)
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json_reverse_iterator& operator++()
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{
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return static_cast<json_reverse_iterator&>(base_iterator::operator++());
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}
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/// post-decrement (it--)
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json_reverse_iterator const operator--(int)
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{
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return static_cast<json_reverse_iterator>(base_iterator::operator--(1));
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}
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/// pre-decrement (--it)
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json_reverse_iterator& operator--()
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{
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return static_cast<json_reverse_iterator&>(base_iterator::operator--());
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}
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/// add to iterator
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json_reverse_iterator& operator+=(difference_type i)
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{
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return static_cast<json_reverse_iterator&>(base_iterator::operator+=(i));
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}
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/// add to iterator
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json_reverse_iterator operator+(difference_type i) const
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{
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return static_cast<json_reverse_iterator>(base_iterator::operator+(i));
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}
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/// subtract from iterator
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json_reverse_iterator operator-(difference_type i) const
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{
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return static_cast<json_reverse_iterator>(base_iterator::operator-(i));
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}
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/// return difference
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difference_type operator-(const json_reverse_iterator& other) const
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{
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return base_iterator(*this) - base_iterator(other);
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}
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/// access to successor
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reference operator[](difference_type n) const
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{
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return *(this->operator+(n));
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}
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/// return the key of an object iterator
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auto key() const -> decltype(std::declval<Base>().key())
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{
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auto it = --this->base();
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return it.key();
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}
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/// return the value of an iterator
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reference value() const
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{
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auto it = --this->base();
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return it.operator * ();
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}
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};
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} // namespace detail
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} // namespace nlohmann
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