basic_json() [7/10]

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, class BinaryType = std::vector<std::uint8_t>>

template<class InputIT , typename std::enable_if< std::is_same< InputIT, typename basic_json_t::iterator >::value||std::is_same< InputIT, typename basic_json_t::const_iterator >::value, int >::type = 0>

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json ( InputIT  first, InputIT  last  )

inline

construct a JSON container given an iterator range

Constructs the JSON value with the contents of the range [first, last). The semantics depends on the different types a JSON value can have:

• In case of a null type, invalid_iterator.206 is thrown.
• In case of other primitive types (number, boolean, or string), first must be begin() and last must be end(). In this case, the value is copied. Otherwise, invalid_iterator.204 is thrown.
• In case of structured types (array, object), the constructor behaves as similar versions for std::vector or std::map; that is, a JSON array or object is constructed from the values in the range.

Template Parameters

InputIT

an input iterator type (iterator or const_iterator)

Parameters

[in]	first	begin of the range to copy from (included)
[in]	last	end of the range to copy from (excluded)

Precondition

Iterators first and last must be initialized. This precondition is enforced with an assertion (see warning). If assertions are switched off, a violation of this precondition yields undefined behavior.

Range [first, last) is valid. Usually, this precondition cannot be checked efficiently. Only certain edge cases are detected; see the description of the exceptions below. A violation of this precondition yields undefined behavior.

Warning

A precondition is enforced with a runtime assertion that will result in calling std::abort if this precondition is not met. Assertions can be disabled by defining NDEBUG at compile time. See https://en.cppreference.com/w/cpp/error/assert for more information.

Exceptions

invalid_iterator.201	if iterators first and last are not compatible (i.e., do not belong to the same JSON value). In this case, the range [first, last) is undefined.
invalid_iterator.204	if iterators first and last belong to a primitive type (number, boolean, or string), but first does not point to the first element any more. In this case, the range [first, last) is undefined. See example code below.
invalid_iterator.206	if iterators first and last belong to a null value. In this case, the range [first, last) is undefined.

@complexity Linear in distance between first and last.

@exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

@liveexample{The example below shows several ways to create JSON values by specifying a subrange with iterators.,basic_json__InputIt_InputIt}

Since

version 1.0.0

Definition at line 19755 of file json.hpp.

    {
        JSON_ASSERT(first.m_object != nullptr);
        JSON_ASSERT(last.m_object != nullptr);
 
        // make sure iterator fits the current value
        if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object))
        {
            JSON_THROW(invalid_iterator::create(201, "iterators are not compatible", basic_json()));
        }
 
        // copy type from first iterator
        m_type = first.m_object->m_type;
 
        // check if iterator range is complete for primitive values
        switch (m_type)
        {
            case value_t::boolean:
            case value_t::number_float:
            case value_t::number_integer:
            case value_t::number_unsigned:
            case value_t::string:
            {
                if (JSON_HEDLEY_UNLIKELY(!first.m_it.primitive_iterator.is_begin()
                                         || !last.m_it.primitive_iterator.is_end()))
                {
                    JSON_THROW(invalid_iterator::create(204, "iterators out of range", *first.m_object));
                }
 
                break;
            }
 
            case value_t::null:
            case value_t::object:
            case value_t::array:
            case value_t::binary:
            case value_t::discarded:
            default:
                break;
        }
 
        switch (m_type)
        {
            case value_t::number_integer:
            {
                m_value.number_integer = first.m_object->m_value.number_integer;
                break;
            }
 
            case value_t::number_unsigned:
            {
                m_value.number_unsigned = first.m_object->m_value.number_unsigned;
                break;
            }
 
            case value_t::number_float:
            {
                m_value.number_float = first.m_object->m_value.number_float;
                break;
            }
 
            case value_t::boolean:
            {
                m_value.boolean = first.m_object->m_value.boolean;
                break;
            }
 
            case value_t::string:
            {
                m_value = *first.m_object->m_value.string;
                break;
            }
 
            case value_t::object:
            {
                m_value.object = create<object_t>(first.m_it.object_iterator,
                                                  last.m_it.object_iterator);
                break;
            }
 
            case value_t::array:
            {
                m_value.array = create<array_t>(first.m_it.array_iterator,
                                                last.m_it.array_iterator);
                break;
            }
 
            case value_t::binary:
            {
                m_value = *first.m_object->m_value.binary;
                break;
            }
 
            case value_t::null:
            case value_t::discarded:
            default:
                JSON_THROW(invalid_iterator::create(206, "cannot construct with iterators from " + std::string(first.m_object->type_name()), *first.m_object));
        }
 
        set_parents();
        assert_invariant();
    }