Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // width.hpp
Chris@16: //
Chris@16: //  Copyright 2008 Eric Niebler. Distributed under the Boost
Chris@16: //  Software License, Version 1.0. (See accompanying file
Chris@16: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_XPRESSIVE_DETAIL_UTILITY_WIDTH_HPP_EAN_04_07_2006
Chris@16: #define BOOST_XPRESSIVE_DETAIL_UTILITY_WIDTH_HPP_EAN_04_07_2006
Chris@16: 
Chris@16: // MS compatible compilers support #pragma once
Chris@101: #if defined(_MSC_VER)
Chris@16: # pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <climits> // for INT_MAX
Chris@16: #include <boost/mpl/size_t.hpp>
Chris@16: 
Chris@16: namespace boost { namespace xpressive { namespace detail
Chris@16: {
Chris@16: 
Chris@16: typedef mpl::size_t<INT_MAX / 2 - 1> unknown_width;
Chris@16: struct width;
Chris@16: bool is_unknown(width const &that);
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // width
Chris@16: struct width
Chris@16: {
Chris@16:     width(std::size_t val = 0)
Chris@16:       : value_(val)
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     bool operator !() const
Chris@16:     {
Chris@16:         return !this->value_;
Chris@16:     }
Chris@16: 
Chris@16:     width &operator +=(width const &that)
Chris@16:     {
Chris@16:         this->value_ =
Chris@16:             !is_unknown(*this) && !is_unknown(that)
Chris@16:           ? this->value_ + that.value_
Chris@16:           : unknown_width();
Chris@16:         return *this;
Chris@16:     }
Chris@16: 
Chris@16:     width &operator |=(width const &that)
Chris@16:     {
Chris@16:         this->value_ =
Chris@16:             this->value_ == that.value_
Chris@16:           ? this->value_
Chris@16:           : unknown_width();
Chris@16:         return *this;
Chris@16:     }
Chris@16: 
Chris@16:     std::size_t value() const
Chris@16:     {
Chris@16:         return this->value_;
Chris@16:     }
Chris@16: 
Chris@16: private:
Chris@16:     std::size_t value_;
Chris@16: };
Chris@16: 
Chris@16: inline bool is_unknown(width const &that)
Chris@16: {
Chris@16:     return unknown_width::value == that.value();
Chris@16: }
Chris@16: 
Chris@16: inline bool operator ==(width const &left, width const &right)
Chris@16: {
Chris@16:     return left.value() == right.value();
Chris@16: }
Chris@16: 
Chris@16: inline bool operator !=(width const &left, width const &right)
Chris@16: {
Chris@16:     return left.value() != right.value();
Chris@16: }
Chris@16: 
Chris@16: inline width operator +(width left, width const &right)
Chris@16: {
Chris@16:     return left += right;
Chris@16: }
Chris@16: 
Chris@16: inline width operator |(width left, width const &right)
Chris@16: {
Chris@16:     return left |= right;
Chris@16: }
Chris@16: 
Chris@16: }}} // namespace boost::xpressive::detail
Chris@16: 
Chris@16: #endif