276 lines
8.5 KiB
C++
Executable File
276 lines
8.5 KiB
C++
Executable File
// Boost Lambda Library - lambda_functors.hpp -------------------------------
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// Copyright (C) 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi)
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// 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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// For more information, see http://www.boost.org
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// ------------------------------------------------
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#ifndef BOOST_LAMBDA_LAMBDA_FUNCTORS_HPP
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#define BOOST_LAMBDA_LAMBDA_FUNCTORS_HPP
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namespace boost {
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namespace lambda {
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// -- lambda_functor --------------------------------------------
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// --------------------------------------------------------------
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//inline const null_type const_null_type() { return null_type(); }
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namespace detail {
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namespace {
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static const null_type constant_null_type = null_type();
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} // unnamed
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} // detail
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class unused {};
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#define cnull_type() detail::constant_null_type
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// -- free variables types --------------------------------------------------
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// helper to work around the case where the nullary return type deduction
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// is always performed, even though the functor is not nullary
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namespace detail {
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template<int N, class Tuple> struct get_element_or_null_type {
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typedef typename
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detail::tuple_element_as_reference<N, Tuple>::type type;
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};
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template<int N> struct get_element_or_null_type<N, null_type> {
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typedef null_type type;
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};
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}
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template <int I> struct placeholder;
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template<> struct placeholder<FIRST> {
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template<class SigArgs> struct sig {
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typedef typename detail::get_element_or_null_type<0, SigArgs>::type type;
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};
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template<class RET, CALL_TEMPLATE_ARGS>
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RET call(CALL_FORMAL_ARGS) const {
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BOOST_STATIC_ASSERT(boost::is_reference<RET>::value);
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CALL_USE_ARGS; // does nothing, prevents warnings for unused args
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return a;
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}
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};
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template<> struct placeholder<SECOND> {
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template<class SigArgs> struct sig {
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typedef typename detail::get_element_or_null_type<1, SigArgs>::type type;
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};
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template<class RET, CALL_TEMPLATE_ARGS>
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RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return b; }
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};
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template<> struct placeholder<THIRD> {
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template<class SigArgs> struct sig {
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typedef typename detail::get_element_or_null_type<2, SigArgs>::type type;
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};
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template<class RET, CALL_TEMPLATE_ARGS>
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RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return c; }
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};
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template<> struct placeholder<EXCEPTION> {
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template<class SigArgs> struct sig {
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typedef typename detail::get_element_or_null_type<3, SigArgs>::type type;
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};
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template<class RET, CALL_TEMPLATE_ARGS>
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RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return env; }
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};
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typedef const lambda_functor<placeholder<FIRST> > placeholder1_type;
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typedef const lambda_functor<placeholder<SECOND> > placeholder2_type;
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typedef const lambda_functor<placeholder<THIRD> > placeholder3_type;
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///////////////////////////////////////////////////////////////////////////////
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// free variables are lambda_functors. This is to allow uniform handling with
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// other lambda_functors.
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// -------------------------------------------------------------------
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// -- lambda_functor NONE ------------------------------------------------
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template <class T>
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class lambda_functor : public T
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{
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BOOST_STATIC_CONSTANT(int, arity_bits = get_arity<T>::value);
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public:
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typedef T inherited;
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lambda_functor() {}
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lambda_functor(const lambda_functor& l) : inherited(l) {}
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lambda_functor(const T& t) : inherited(t) {}
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template <class SigArgs> struct sig {
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typedef typename inherited::template
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sig<typename SigArgs::tail_type>::type type;
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};
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// Note that this return type deduction template is instantiated, even
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// if the nullary
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// operator() is not called at all. One must make sure that it does not fail.
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typedef typename
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inherited::template sig<null_type>::type
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nullary_return_type;
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nullary_return_type operator()() const {
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return inherited::template
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call<nullary_return_type>
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(cnull_type(), cnull_type(), cnull_type(), cnull_type());
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}
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template<class A>
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typename inherited::template sig<tuple<A&> >::type
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operator()(A& a) const {
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return inherited::template call<
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typename inherited::template sig<tuple<A&> >::type
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>(a, cnull_type(), cnull_type(), cnull_type());
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}
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template<class A>
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typename inherited::template sig<tuple<A const&> >::type
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operator()(A const& a) const {
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return inherited::template call<
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typename inherited::template sig<tuple<A const&> >::type
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>(a, cnull_type(), cnull_type(), cnull_type());
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}
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template<class A, class B>
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typename inherited::template sig<tuple<A&, B&> >::type
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operator()(A& a, B& b) const {
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return inherited::template call<
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typename inherited::template sig<tuple<A&, B&> >::type
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>(a, b, cnull_type(), cnull_type());
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}
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template<class A, class B>
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typename inherited::template sig<tuple<A const&, B&> >::type
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operator()(A const& a, B& b) const {
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return inherited::template call<
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typename inherited::template sig<tuple<A const&, B&> >::type
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>(a, b, cnull_type(), cnull_type());
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}
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template<class A, class B>
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typename inherited::template sig<tuple<A&, B const&> >::type
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operator()(A& a, B const& b) const {
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return inherited::template call<
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typename inherited::template sig<tuple<A&, B const&> >::type
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>(a, b, cnull_type(), cnull_type());
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}
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template<class A, class B>
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typename inherited::template sig<tuple<A const&, B const&> >::type
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operator()(A const& a, B const& b) const {
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return inherited::template call<
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typename inherited::template sig<tuple<A const&, B const&> >::type
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>(a, b, cnull_type(), cnull_type());
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}
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template<class A, class B, class C>
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typename inherited::template sig<tuple<A&, B&, C&> >::type
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operator()(A& a, B& b, C& c) const
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{
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return inherited::template call<
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typename inherited::template sig<tuple<A&, B&, C&> >::type
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>(a, b, c, cnull_type());
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}
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template<class A, class B, class C>
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typename inherited::template sig<tuple<A const&, B const&, C const&> >::type
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operator()(A const& a, B const& b, C const& c) const
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{
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return inherited::template call<
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typename inherited::template sig<tuple<A const&, B const&, C const&> >::type
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>(a, b, c, cnull_type());
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}
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// for internal calls with env
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template<CALL_TEMPLATE_ARGS>
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typename inherited::template sig<tuple<CALL_REFERENCE_TYPES> >::type
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internal_call(CALL_FORMAL_ARGS) const {
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return inherited::template
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call<typename inherited::template
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sig<tuple<CALL_REFERENCE_TYPES> >::type>(CALL_ACTUAL_ARGS);
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}
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template<class A>
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const lambda_functor<lambda_functor_base<
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other_action<assignment_action>,
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boost::tuple<lambda_functor,
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typename const_copy_argument <const A>::type> > >
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operator=(const A& a) const {
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return lambda_functor_base<
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other_action<assignment_action>,
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boost::tuple<lambda_functor,
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typename const_copy_argument <const A>::type> >
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( boost::tuple<lambda_functor,
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typename const_copy_argument <const A>::type>(*this, a) );
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}
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template<class A>
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const lambda_functor<lambda_functor_base<
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other_action<subscript_action>,
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boost::tuple<lambda_functor,
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typename const_copy_argument <const A>::type> > >
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operator[](const A& a) const {
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return lambda_functor_base<
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other_action<subscript_action>,
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boost::tuple<lambda_functor,
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typename const_copy_argument <const A>::type> >
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( boost::tuple<lambda_functor,
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typename const_copy_argument <const A>::type>(*this, a ) );
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}
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};
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} // namespace lambda
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} // namespace boost
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// is_placeholder
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#include <boost/is_placeholder.hpp>
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namespace boost
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{
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template<> struct is_placeholder< lambda::lambda_functor< lambda::placeholder<lambda::FIRST> > >
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{
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enum _vt { value = 1 };
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};
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template<> struct is_placeholder< lambda::lambda_functor< lambda::placeholder<lambda::SECOND> > >
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{
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enum _vt { value = 2 };
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};
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template<> struct is_placeholder< lambda::lambda_functor< lambda::placeholder<lambda::THIRD> > >
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{
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enum _vt { value = 3 };
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};
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} // namespace boost
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#endif
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