1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
///////////////////////////////////////////////////////////////////////////////
// keeper_matcher.hpp
//
// Copyright 2008 Eric Niebler. 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)
#ifndef BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_KEEPER_MATCHER_HPP_EAN_10_04_2005
#define BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_KEEPER_MATCHER_HPP_EAN_10_04_2005
// MS compatible compilers support #pragma once
#if defined(_MSC_VER)
# pragma once
#endif
#include <boost/mpl/bool.hpp>
#include <boost/xpressive/detail/detail_fwd.hpp>
#include <boost/xpressive/detail/core/quant_style.hpp>
#include <boost/xpressive/detail/core/state.hpp>
namespace boost { namespace xpressive { namespace detail
{
///////////////////////////////////////////////////////////////////////////////
// keeper_matcher
// Xpr can be either a static_xpression, or a shared_matchable
template<typename Xpr>
struct keeper_matcher
: quant_style<quant_variable_width, unknown_width::value, Xpr::pure>
{
keeper_matcher(Xpr const &xpr, bool pure = Xpr::pure)
: xpr_(xpr)
, pure_(pure)
{
}
template<typename BidiIter, typename Next>
bool match(match_state<BidiIter> &state, Next const &next) const
{
return Xpr::pure || this->pure_
? this->match_(state, next, mpl::true_())
: this->match_(state, next, mpl::false_());
}
template<typename BidiIter, typename Next>
bool match_(match_state<BidiIter> &state, Next const &next, mpl::true_) const
{
BidiIter const tmp = state.cur_;
// matching xpr is guaranteed to not produce side-effects, don't bother saving state
if(!this->xpr_.match(state))
{
return false;
}
else if(next.match(state))
{
return true;
}
state.cur_ = tmp;
return false;
}
template<typename BidiIter, typename Next>
bool match_(match_state<BidiIter> &state, Next const &next, mpl::false_) const
{
BidiIter const tmp = state.cur_;
// matching xpr could produce side-effects, save state
memento<BidiIter> mem = save_sub_matches(state);
if(!this->xpr_.match(state))
{
restore_action_queue(mem, state);
reclaim_sub_matches(mem, state, false);
return false;
}
restore_action_queue(mem, state);
if(next.match(state))
{
reclaim_sub_matches(mem, state, true);
return true;
}
restore_sub_matches(mem, state);
state.cur_ = tmp;
return false;
}
Xpr xpr_;
bool pure_; // false if matching xpr_ could modify the sub-matches
};
}}}
#endif
|
