JSON for Modern C++
3.5.0
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◆ iterator_wrapper() [2/2]
template<template< typename U, typename V, typename... Args > class ObjectType = std::map, template< typename U, typename... Args > class ArrayType = std::vector, class StringType = std::string, class BooleanType = bool, class NumberIntegerType = std::int64_t, class NumberUnsignedType = std::uint64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator, template< typename T, typename SFINAE=void > class JSONSerializer = adl_serializer>
This function allows to access iterator::key() and iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator. For loop without iterator_wrapper: for (auto it = j_object.begin(); it != j_object.end(); ++it) { std::cout << "key: " << it.key() << ", value:" << it.value() << '\n'; } Range-based for loop without iterator proxy: for (auto it : j_object) { // "it" is of type json::reference and has no key() member std::cout << "value: " << it << '\n'; } Range-based for loop with iterator proxy: { std::cout << "key: " << it.key() << ", value:" << it.value() << '\n'; }
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