1/*==============================================================================
2 Copyright (c) 2001-2010 Joel de Guzman
3 Copyright (c) 2010 Thomas Heller
4
5 Distributed under the Boost Software License, Version 1.0. (See accompanying
6 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7==============================================================================*/
8#ifndef BOOST_PHOENIX_CORE_REFERENCE_HPP
9#define BOOST_PHOENIX_CORE_REFERENCE_HPP
10
11#include <boost/phoenix/core/limits.hpp>
12#include <boost/ref.hpp>
13#include <boost/phoenix/core/actor.hpp>
14#include <boost/phoenix/core/terminal.hpp>
15#include <boost/utility/result_of.hpp>
16
17namespace boost { namespace phoenix
18{
19 /////////////////////////////////////////////////////////////////////////////
20 //
21 // reference
22 //
23 // function for evaluating references, e.g. ref(123)
24 //
25 /////////////////////////////////////////////////////////////////////////////
26 namespace expression
27 {
28 template <typename T>
29 struct reference
30 : expression::terminal<reference_wrapper<T> >
31 {
32 typedef
33 typename expression::terminal<reference_wrapper<T> >::type
34 type;
35
36 static const type make(T & t)
37 {
38 typename reference<T>::type const e = {{boost::ref(t)}};
39 return e;
40 }
41 };
42
43 template <typename T>
44 struct reference<T const>
45 : expression::terminal<reference_wrapper<T const> >
46 {
47 typedef
48 typename expression::terminal<reference_wrapper<T const> >::type
49 type;
50
51 static const type make(T const & t)
52 {
53 typename reference<T const>::type const e = {{boost::cref(t)}};
54 return e;
55 }
56 };
57 }
58
59 namespace rule
60 {
61 struct reference
62 : expression::reference<proto::_>
63 {};
64 }
65
66 template <typename T>
67 inline
68 typename expression::reference<T>::type const
69 ref(T & t)
70 {
71 return expression::reference<T>::make(t);
72 }
73
74 template <typename T>
75 inline
76 typename expression::reference<T const>::type const
77 cref(T const & t)
78 {
79 return expression::reference<T const>::make(t);
80 }
81
82 // Call out boost::reference_wrapper for special handling
83 template<typename T>
84 struct is_custom_terminal<boost::reference_wrapper<T> >
85 : mpl::true_
86 {};
87
88 // Special handling for boost::reference_wrapper
89 template<typename T>
90 struct custom_terminal<boost::reference_wrapper<T> >
91 {
92 typedef T &result_type;
93
94 template <typename Context>
95 T &operator()(boost::reference_wrapper<T> r, Context &) const
96 {
97 return r;
98 }
99 };
100
101 template<typename Expr>
102 struct custom_terminal<boost::reference_wrapper<actor<Expr> > >
103 {
104 template <typename Sig>
105 struct result;
106
107 template <typename This, typename Context>
108 struct result<This(boost::reference_wrapper<actor<Expr> > const &, Context)>
109 : boost::result_of<evaluator(actor<Expr> &, Context)>
110 {};
111
112 template <typename This, typename Context>
113 struct result<This(boost::reference_wrapper<actor<Expr> > &, Context)>
114 : boost::result_of<evaluator(actor<Expr> &, Context)>
115 {};
116
117 template <typename Context>
118 typename boost::result_of<evaluator(actor<Expr> &, Context const &)>::type
119 operator()(boost::reference_wrapper<actor<Expr> > & r, Context const & ctx) const
120 {
121 return boost::phoenix::eval(r, ctx);
122 }
123 };
124
125 template<typename Expr>
126 struct custom_terminal<boost::reference_wrapper<actor<Expr> const> >
127 {
128 template <typename Sig>
129 struct result;
130
131 template <typename This, typename Context>
132 struct result<This(boost::reference_wrapper<actor<Expr> const> const &, Context)>
133 : boost::result_of<evaluator(actor<Expr> const&, Context)>
134 {};
135
136 template <typename This, typename Context>
137 struct result<This(boost::reference_wrapper<actor<Expr> const> &, Context)>
138 : boost::result_of<evaluator(actor<Expr> const&, Context)>
139 {};
140
141 template <typename Context>
142 typename boost::result_of<evaluator(actor<Expr> const&, Context const &)>::type
143 operator()(boost::reference_wrapper<actor<Expr> const> const & r, Context & ctx) const
144 {
145 return boost::phoenix::eval(unwrap_ref(r), ctx);
146 }
147 };
148}}
149
150#endif
151