Boost C++ Libraries

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ref_unwrapped

ref_unwrapped

ref_unwrapped example

Syntax	Code
Pipe	`rng \| boost::adaptors::ref_unwrapped`
Function	`boost::adaptors::ref_unwrap(rng)`

This adaptor produces a range than applies .get() on all values in the range. It is useful for iterating ranges of std::reference_wrapper values or values using similar semantics.

The adaptor is C++11 (and above) only.

Precondition: The value_type of the range has a .get() const.
Postcondition: For all elements x in the returned range, x is the result of y.get() where y is the corresponding element in the original range.
Range Category: Single Pass Range
Range Return Type: boost::unwrap_ref_range<decltype(rng)>
Returned Range Category: The range category of rng.

ref_unwrapped example

#include <boost/range/adaptor/ref_unwrapped.hpp>
#include <iostream>
#include <vector>

struct example
{
  int value;
};

int main(int argc, const char* argv[])
{
    using boost::adaptors::ref_unwrapped;

    example one{1};
    example two{2};
    example three{3};

    std::vector<std::reference_wrapper<example> > input{one, two, three};

    for (auto&& entry : input | ref_unwrapped)
    {
      std::cout << entry.value;
    }

    return 0;
}

This would produce the output 123.