87 lines
2.1 KiB
C++
87 lines
2.1 KiB
C++
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//---------------------------------------------------------------------------//
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// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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// See http://boostorg.github.com/compute for more information.
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//---------------------------------------------------------------------------//
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#ifndef BOOST_COMPUTE_FUNCTIONAL_FIELD_HPP
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#define BOOST_COMPUTE_FUNCTIONAL_FIELD_HPP
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#include <string>
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namespace boost {
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namespace compute {
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namespace detail {
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template<class T, class Arg>
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struct invoked_field
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{
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typedef T result_type;
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invoked_field(const Arg &arg, const std::string &field)
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: m_arg(arg),
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m_field(field)
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{
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}
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Arg m_arg;
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std::string m_field;
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};
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} // end detail namespace
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/// Returns the named field from a value.
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///
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/// The template-type \c T specifies the field's value type. Note
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/// that the value type must match the actual type of the field
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/// otherwise runtime compilation or logic errors may occur.
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///
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/// For example, to access the \c second field in a
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/// \c std::pair<int, float> object:
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/// \code
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/// field<float>("second");
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/// \endcode
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///
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/// This can also be used with vector types to access individual
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/// components as well as perform swizzle operations.
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///
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/// For example, to access the first and third components of an
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/// \c int vector type (e.g. \c int4):
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/// \code
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/// field<int2_>("xz");
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/// \endcode
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///
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/// \see \ref get "get<N>"
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template<class T>
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class field
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{
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public:
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/// Result type.
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typedef T result_type;
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/// Creates a new field functor with \p field.
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field(const std::string &field)
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: m_field(field)
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{
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}
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/// \internal_
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template<class Arg>
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detail::invoked_field<T, Arg> operator()(const Arg &arg) const
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{
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return detail::invoked_field<T, Arg>(arg, m_field);
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}
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private:
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std::string m_field;
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};
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} // end compute namespace
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} // end boost namespace
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#endif // BOOST_COMPUTE_FUNCTIONAL_FIELD_HPP
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