///////////////////////////////////////////////////////////////////////////////
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// width.hpp
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//
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// Copyright 2008 Eric Niebler. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_XPRESSIVE_DETAIL_UTILITY_WIDTH_HPP_EAN_04_07_2006
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#define BOOST_XPRESSIVE_DETAIL_UTILITY_WIDTH_HPP_EAN_04_07_2006
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// MS compatible compilers support #pragma once
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#if defined(_MSC_VER)
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# pragma once
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#endif
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#include <climits> // for INT_MAX
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#include <boost/mpl/size_t.hpp>
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namespace boost { namespace xpressive { namespace detail
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{
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typedef mpl::size_t<INT_MAX / 2 - 1> unknown_width;
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struct width;
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bool is_unknown(width const &that);
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///////////////////////////////////////////////////////////////////////////////
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// width
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struct width
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{
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width(std::size_t val = 0)
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: value_(val)
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{
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}
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bool operator !() const
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{
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return !this->value_;
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}
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width &operator +=(width const &that)
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{
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this->value_ =
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!is_unknown(*this) && !is_unknown(that)
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? this->value_ + that.value_
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: unknown_width();
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return *this;
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}
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width &operator |=(width const &that)
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{
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this->value_ =
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this->value_ == that.value_
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? this->value_
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: unknown_width();
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return *this;
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}
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std::size_t value() const
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{
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return this->value_;
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}
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private:
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std::size_t value_;
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};
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inline bool is_unknown(width const &that)
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{
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return unknown_width::value == that.value();
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}
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inline bool operator ==(width const &left, width const &right)
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{
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return left.value() == right.value();
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}
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inline bool operator !=(width const &left, width const &right)
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{
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return left.value() != right.value();
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}
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inline width operator +(width left, width const &right)
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{
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return left += right;
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}
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inline width operator |(width left, width const &right)
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{
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return left |= right;
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}
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}}} // namespace boost::xpressive::detail
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#endif
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