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1 | /////////////////////////////////////////////////////////////////////////////// |
2 | // width.hpp | |
3 | // | |
4 | // Copyright 2008 Eric Niebler. Distributed under the Boost | |
5 | // Software License, Version 1.0. (See accompanying file | |
6 | // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
7 | ||
8 | #ifndef BOOST_XPRESSIVE_DETAIL_UTILITY_WIDTH_HPP_EAN_04_07_2006 | |
9 | #define BOOST_XPRESSIVE_DETAIL_UTILITY_WIDTH_HPP_EAN_04_07_2006 | |
10 | ||
11 | // MS compatible compilers support #pragma once | |
12 | #if defined(_MSC_VER) | |
13 | # pragma once | |
14 | #endif | |
15 | ||
16 | #include <climits> // for INT_MAX | |
17 | #include <boost/mpl/size_t.hpp> | |
18 | ||
19 | namespace boost { namespace xpressive { namespace detail | |
20 | { | |
21 | ||
22 | typedef mpl::size_t<INT_MAX / 2 - 1> unknown_width; | |
23 | struct width; | |
24 | bool is_unknown(width const &that); | |
25 | ||
26 | /////////////////////////////////////////////////////////////////////////////// | |
27 | // width | |
28 | struct width | |
29 | { | |
30 | width(std::size_t val = 0) | |
31 | : value_(val) | |
32 | { | |
33 | } | |
34 | ||
35 | bool operator !() const | |
36 | { | |
37 | return !this->value_; | |
38 | } | |
39 | ||
40 | width &operator +=(width const &that) | |
41 | { | |
42 | this->value_ = | |
43 | !is_unknown(*this) && !is_unknown(that) | |
44 | ? this->value_ + that.value_ | |
45 | : unknown_width(); | |
46 | return *this; | |
47 | } | |
48 | ||
49 | width &operator |=(width const &that) | |
50 | { | |
51 | this->value_ = | |
52 | this->value_ == that.value_ | |
53 | ? this->value_ | |
54 | : unknown_width(); | |
55 | return *this; | |
56 | } | |
57 | ||
58 | std::size_t value() const | |
59 | { | |
60 | return this->value_; | |
61 | } | |
62 | ||
63 | private: | |
64 | std::size_t value_; | |
65 | }; | |
66 | ||
67 | inline bool is_unknown(width const &that) | |
68 | { | |
69 | return unknown_width::value == that.value(); | |
70 | } | |
71 | ||
72 | inline bool operator ==(width const &left, width const &right) | |
73 | { | |
74 | return left.value() == right.value(); | |
75 | } | |
76 | ||
77 | inline bool operator !=(width const &left, width const &right) | |
78 | { | |
79 | return left.value() != right.value(); | |
80 | } | |
81 | ||
82 | inline width operator +(width left, width const &right) | |
83 | { | |
84 | return left += right; | |
85 | } | |
86 | ||
87 | inline width operator |(width left, width const &right) | |
88 | { | |
89 | return left |= right; | |
90 | } | |
91 | ||
92 | }}} // namespace boost::xpressive::detail | |
93 | ||
94 | #endif |