boost::gil::histogram::try_emplace

Attempts to build and insert a std::pair into the %unordered_map.

Synopsis

Declared in <boost/gil/histogram.hpp>

template<typename... _Args>
iterator
try_emplace(
    const_iterator __hint,
    key_type const& __k,
    _Args&&... __args);

Description

This function is not concerned about whether the insertion took place, and thus does not return a boolean like the single‐argument emplace() does. However, if insertion did not take place, this function has no effect. Note that the first parameter is only a hint and can potentially improve the performance of the insertion process. A bad hint would cause no gains in efficiency.

See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints for more on hinting.

Insertion requires amortized constant time.

Return Value

An iterator that points to the element with key of the std::pair built from __args (may or may not be that std::pair).

Parameters

Name

Description

__hint

An iterator that serves as a hint as to where the pair should be inserted.

__k

Key to use for finding a possibly existing pair in the unordered_map.

__args

Arguments used to generate the .second for a new pair instance.

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