| [/ |
| Copyright 2010 Neil Groves |
| Distributed under the Boost Software License, Version 1.0. |
| (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| /] |
| [section:map_keys map_keys] |
| |
| [table |
| [[Syntax] [Code]] |
| [[Pipe] [`rng | boost::adaptors::map_keys`]] |
| [[Function] [`boost::adaptors::keys(rng)`]] |
| ] |
| |
| * [*Precondition:] The `value_type` of the range is an instantiation of `std::pair`. |
| * [*Postcondition:] For all elements `x` in the returned range, `x` is the result of `y.first` where `y` is the corresponding element in the original range. |
| * [*Range Category:] __single_pass_range__ |
| * [*Range Return Type:] `boost::select_first_range<decltype(rng)>` |
| * [*Returned Range Category:] The range category of `rng`. |
| |
| [section:map_keys_example map_keys example] |
| [import ../../../test/adaptor_test/map_keys_example.cpp] |
| [map_keys_example] |
| [endsect] |
| |
| This would produce the output: |
| `` |
| 0,1,2,3,4,5,6,7,8,9, |
| `` |
| [endsect] |
| |
| |
