erase() [4/4]

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

IteratorType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::erase ( IteratorType  pos )

inline

remove element given an iterator

Removes the element specified by iterator pos. The iterator pos must be valid and dereferenceable. Thus the end() iterator (which is valid, but is not dereferenceable) cannot be used as a value for pos.

If called on a primitive type other than null, the resulting JSON value will be null.

Parameters

[in]

pos

iterator to the element to remove

Returns

Iterator following the last removed element. If the iterator pos refers to the last element, the end() iterator is returned.

Template Parameters

IteratorType

an iterator or const_iterator

Postcondition

Invalidates iterators and references at or after the point of the erase, including the end() iterator.

Exceptions

type_error.307	if called on a null value; example: "cannot use erase() with null"
invalid_iterator.202	if called on an iterator which does not belong to the current JSON value; example: "iterator does not fit current value"
invalid_iterator.205	if called on a primitive type with invalid iterator (i.e., any iterator which is not begin()); example: "iterator out of range"

@complexity The complexity depends on the type:

• objects: amortized constant
• arrays: linear in distance between pos and the end of the container
• strings and binary: linear in the length of the member
• other types: constant

@liveexample{The example shows the result of erase() for different JSON types.,erase__IteratorType}

See also

see erase(IteratorType, IteratorType) – removes the elements in the given range

see erase(const typename object_t::key_type&) – removes the element from an object at the given key

see erase(const size_type) – removes the element from an array at the given index

Since

version 1.0.0

Definition at line 21920 of file json.hpp.

    {
        // make sure iterator fits the current value
        if (JSON_HEDLEY_UNLIKELY(this != pos.m_object))
        {
            JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", *this));
        }
 
        IteratorType result = end();
 
        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:
            case value_t::binary:
            {
                if (JSON_HEDLEY_UNLIKELY(!pos.m_it.primitive_iterator.is_begin()))
                {
                    JSON_THROW(invalid_iterator::create(205, "iterator out of range", *this));
                }
 
                if (is_string())
                {
                    AllocatorType<string_t> alloc;
                    std::allocator_traits<decltype(alloc)>::destroy(alloc, m_value.string);
                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, m_value.string, 1);
                    m_value.string = nullptr;
                }
 
                else if (is_binary())
                {
                    AllocatorType<binary_t> alloc;
                    std::allocator_traits<decltype(alloc)>::destroy(alloc, m_value.binary);
                    std::allocator_traits<decltype(alloc)>::deallocate(alloc, m_value.binary, 1);
                    m_value.binary = nullptr;
                }
 
                m_type = value_t::null;
                assert_invariant();
                break;
            }
 
            case value_t::object:
            {
                result.m_it.object_iterator = m_value.object->erase(pos.m_it.object_iterator);
                break;
            }
 
            case value_t::array:
            {
                result.m_it.array_iterator = m_value.array->erase(pos.m_it.array_iterator);
                break;
            }
 
            case value_t::null:
            case value_t::discarded:
            default:
                JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name()), *this));
        }
 
        return result;
    }