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1 | /////////////////////////////////////////////////////////////////////////////// | |
2 | /// \file eval.hpp | |
3 | /// Contains the eval() expression evaluator. | |
4 | // | |
5 | // Copyright 2008 Eric Niebler. Distributed under the Boost | |
6 | // Software License, Version 1.0. (See accompanying file | |
7 | // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
8 | ||
9 | #ifndef BOOST_PROTO_EVAL_HPP_EAN_03_29_2007 | |
10 | #define BOOST_PROTO_EVAL_HPP_EAN_03_29_2007 | |
11 | ||
12 | #include <boost/proto/proto_fwd.hpp> // BOOST_PROTO_CALLABLE | |
13 | #include <boost/type_traits/remove_reference.hpp> | |
14 | ||
15 | namespace boost { namespace proto | |
16 | { | |
17 | ||
18 | namespace result_of | |
19 | { | |
20 | /// \brief A metafunction for calculating the return type | |
21 | /// of \c proto::eval() given a certain \c Expr and \c Context | |
22 | /// types. | |
23 | /// | |
24 | /// \note The types \c Expr and \c Context should not be | |
25 | /// reference types. They may be cv-qualified, but the | |
26 | /// cv-qualification on the \c Context parameter is ignored. | |
27 | template<typename Expr, typename Context> | |
28 | struct eval | |
29 | { | |
30 | typedef typename Context::template eval<Expr>::result_type type; | |
31 | }; | |
32 | } | |
33 | ||
34 | namespace functional | |
35 | { | |
36 | /// \brief A PolymorphicFunctionObject type for | |
37 | /// evaluating a given Proto expression with a given | |
38 | /// context. | |
39 | struct eval | |
40 | { | |
41 | BOOST_PROTO_CALLABLE() | |
42 | ||
43 | template<typename Sig> | |
44 | struct result; | |
45 | ||
46 | template<typename This, typename Expr, typename Context> | |
47 | struct result<This(Expr, Context)> | |
48 | { | |
49 | typedef | |
50 | typename proto::result_of::eval< | |
51 | typename remove_reference<Expr>::type | |
52 | , typename remove_reference<Context>::type | |
53 | >::type | |
54 | type; | |
55 | }; | |
56 | ||
57 | /// \brief Evaluate a given Proto expression with a given | |
58 | /// context. | |
59 | /// \param expr The Proto expression to evaluate | |
60 | /// \param context The context in which the expression should be | |
61 | /// evaluated. | |
62 | /// \return <tt>typename Context::template eval<Expr>()(expr, context)</tt> | |
63 | template<typename Expr, typename Context> | |
64 | typename proto::result_of::eval<Expr, Context>::type | |
65 | operator ()(Expr &e, Context &ctx) const | |
66 | { | |
67 | return typename Context::template eval<Expr>()(e, ctx); | |
68 | } | |
69 | ||
70 | /// \overload | |
71 | /// | |
72 | template<typename Expr, typename Context> | |
73 | typename proto::result_of::eval<Expr, Context>::type | |
74 | operator ()(Expr &e, Context const &ctx) const | |
75 | { | |
76 | return typename Context::template eval<Expr>()(e, ctx); | |
77 | } | |
78 | ||
79 | /// \overload | |
80 | /// | |
81 | template<typename Expr, typename Context> | |
82 | typename proto::result_of::eval<Expr const, Context>::type | |
83 | operator ()(Expr const &e, Context &ctx) const | |
84 | { | |
85 | return typename Context::template eval<Expr const>()(e, ctx); | |
86 | } | |
87 | ||
88 | /// \overload | |
89 | /// | |
90 | template<typename Expr, typename Context> | |
91 | typename proto::result_of::eval<Expr const, Context>::type | |
92 | operator ()(Expr const &e, Context const &ctx) const | |
93 | { | |
94 | return typename Context::template eval<Expr const>()(e, ctx); | |
95 | } | |
96 | }; | |
97 | } | |
98 | ||
99 | /// \brief Evaluate a given Proto expression with a given | |
100 | /// context. | |
101 | /// \param expr The Proto expression to evaluate | |
102 | /// \param context The context in which the expression should be | |
103 | /// evaluated. | |
104 | /// \return <tt>typename Context::template eval<Expr>()(expr, context)</tt> | |
105 | template<typename Expr, typename Context> | |
106 | typename proto::result_of::eval<Expr, Context>::type | |
107 | eval(Expr &e, Context &ctx) | |
108 | { | |
109 | return typename Context::template eval<Expr>()(e, ctx); | |
110 | } | |
111 | ||
112 | /// \overload | |
113 | /// | |
114 | template<typename Expr, typename Context> | |
115 | typename proto::result_of::eval<Expr, Context>::type | |
116 | eval(Expr &e, Context const &ctx) | |
117 | { | |
118 | return typename Context::template eval<Expr>()(e, ctx); | |
119 | } | |
120 | ||
121 | /// \overload | |
122 | /// | |
123 | template<typename Expr, typename Context> | |
124 | typename proto::result_of::eval<Expr const, Context>::type | |
125 | eval(Expr const &e, Context &ctx) | |
126 | { | |
127 | return typename Context::template eval<Expr const>()(e, ctx); | |
128 | } | |
129 | ||
130 | /// \overload | |
131 | /// | |
132 | template<typename Expr, typename Context> | |
133 | typename proto::result_of::eval<Expr const, Context>::type | |
134 | eval(Expr const &e, Context const &ctx) | |
135 | { | |
136 | return typename Context::template eval<Expr const>()(e, ctx); | |
137 | } | |
138 | }} | |
139 | ||
140 | #endif |