98 lines
2.5 KiB
C++
98 lines
2.5 KiB
C++
#pragma once
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#include <cstddef> // size_t
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#include <string> // string, to_string
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#include "detail/value_t.hpp"
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namespace nlohmann
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{
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namespace detail
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{
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/// proxy class for the items() function
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template<typename IteratorType> class iteration_proxy
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{
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private:
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/// helper class for iteration
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class iteration_proxy_internal
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{
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private:
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/// the iterator
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IteratorType anchor;
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/// an index for arrays (used to create key names)
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std::size_t array_index = 0;
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public:
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explicit iteration_proxy_internal(IteratorType it) noexcept : anchor(it) {}
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/// dereference operator (needed for range-based for)
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iteration_proxy_internal& operator*()
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{
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return *this;
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}
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/// increment operator (needed for range-based for)
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iteration_proxy_internal& operator++()
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{
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++anchor;
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++array_index;
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return *this;
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}
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/// inequality operator (needed for range-based for)
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bool operator!=(const iteration_proxy_internal& o) const noexcept
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{
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return anchor != o.anchor;
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}
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/// return key of the iterator
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std::string key() const
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{
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assert(anchor.m_object != nullptr);
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switch (anchor.m_object->type())
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{
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// use integer array index as key
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case value_t::array:
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return std::to_string(array_index);
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// use key from the object
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case value_t::object:
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return anchor.key();
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// use an empty key for all primitive types
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default:
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return "";
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}
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}
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/// return value of the iterator
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typename IteratorType::reference value() const
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{
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return anchor.value();
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}
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};
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/// the container to iterate
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typename IteratorType::reference container;
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public:
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/// construct iteration proxy from a container
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explicit iteration_proxy(typename IteratorType::reference cont) noexcept
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: container(cont) {}
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/// return iterator begin (needed for range-based for)
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iteration_proxy_internal begin() noexcept
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{
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return iteration_proxy_internal(container.begin());
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}
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/// return iterator end (needed for range-based for)
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iteration_proxy_internal end() noexcept
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{
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return iteration_proxy_internal(container.end());
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}
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};
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}
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}
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