boost/xpressive/detail/static/static.hpp
/////////////////////////////////////////////////////////////////////////////// // static.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_STATIC_STATIC_HPP_EAN_10_04_2005 #define BOOST_XPRESSIVE_DETAIL_STATIC_STATIC_HPP_EAN_10_04_2005 // MS compatible compilers support #pragma once #if defined(_MSC_VER) # pragma once #endif #include <boost/mpl/assert.hpp> #include <boost/xpressive/detail/detail_fwd.hpp> #include <boost/xpressive/detail/core/state.hpp> #include <boost/xpressive/detail/core/linker.hpp> #include <boost/xpressive/detail/core/peeker.hpp> #include <boost/xpressive/detail/static/placeholders.hpp> #include <boost/xpressive/detail/utility/width.hpp> // Random thoughts: // - must support indirect repeat counts {$n,$m} // - add ws to eat whitespace (make *ws illegal) // - a{n,m} -> repeat<n,m>(a) // - a{$n,$m} -> repeat(n,m)(a) // - add nil to match nothing // - instead of s1, s2, etc., how about s[1], s[2], etc.? Needlessly verbose? namespace boost { namespace xpressive { namespace detail { /////////////////////////////////////////////////////////////////////////////// // stacked_xpression // template<typename Top, typename Next> struct stacked_xpression : Next { // match // delegates to Next template<typename BidiIter> bool match(match_state<BidiIter> &state) const { return static_cast<Next const *>(this)-> BOOST_NESTED_TEMPLATE push_match<Top>(state); } // top_match // jump back to the xpression on top of the xpression stack, // and keep the xpression on the stack. template<typename BidiIter> static bool top_match(match_state<BidiIter> &state, void const *top) { return static_cast<Top const *>(top)-> BOOST_NESTED_TEMPLATE push_match<Top>(state); } // pop_match // jump back to the xpression on top of the xpression stack, // pop the xpression off the stack. template<typename BidiIter> static bool pop_match(match_state<BidiIter> &state, void const *top) { return static_cast<Top const *>(top)->match(state); } // skip_match // pop the xpression off the top of the stack and ignore it; call // match on next. template<typename BidiIter> bool skip_match(match_state<BidiIter> &state) const { // could be static_xpression::skip_impl or stacked_xpression::skip_impl // depending on if there is 1 or more than 1 xpression on the // xpression stack return Top::skip_impl(*static_cast<Next const *>(this), state); } //protected: // skip_impl // implementation of skip_match. template<typename That, typename BidiIter> static bool skip_impl(That const &that, match_state<BidiIter> &state) { return that.BOOST_NESTED_TEMPLATE push_match<Top>(state); } }; /////////////////////////////////////////////////////////////////////////////// // stacked_xpression_cast // template<typename Top, typename Next> inline stacked_xpression<Top, Next> const &stacked_xpression_cast(Next const &next) { // NOTE: this is a little white lie. The "next" object doesn't really have // the type to which we're casting it. It is harmless, though. We are only using // the cast to decorate the next object with type information. It is done // this way to save stack space. BOOST_MPL_ASSERT_RELATION(sizeof(stacked_xpression<Top, Next>), ==, sizeof(Next)); return *static_cast<stacked_xpression<Top, Next> const *>(&next); } /////////////////////////////////////////////////////////////////////////////// // static_xpression // template<typename Matcher, typename Next> struct static_xpression : Matcher { Next next_; BOOST_STATIC_CONSTANT(bool, pure = Matcher::pure && Next::pure); BOOST_STATIC_CONSTANT( std::size_t , width = Matcher::width != unknown_width::value && Next::width != unknown_width::value ? Matcher::width + Next::width : unknown_width::value ); static_xpression(Matcher const &matcher = Matcher(), Next const &next = Next()) : Matcher(matcher) , next_(next) { } // match // delegates to the Matcher template<typename BidiIter> bool match(match_state<BidiIter> &state) const { return this->Matcher::match(state, this->next_); } // push_match // call match on this, but also push "Top" onto the xpression // stack so we know what we are jumping back to later. template<typename Top, typename BidiIter> bool push_match(match_state<BidiIter> &state) const { return this->Matcher::match(state, stacked_xpression_cast<Top>(this->next_)); } // skip_impl // implementation of skip_match, called from stacked_xpression::skip_match template<typename That, typename BidiIter> static bool skip_impl(That const &that, match_state<BidiIter> &state) { return that.match(state); } // for linking a compiled regular xpression template<typename Char> void link(xpression_linker<Char> &linker) const { linker.accept(*static_cast<Matcher const *>(this), &this->next_); this->next_.link(linker); } // for building a lead-follow template<typename Char> void peek(xpression_peeker<Char> &peeker) const { this->peek_next_(peeker.accept(*static_cast<Matcher const *>(this)), peeker); } // for getting xpression width detail::width get_width() const { return this->get_width_(mpl::size_t<width>()); } private: static_xpression &operator =(static_xpression const &); template<typename Char> void peek_next_(mpl::true_, xpression_peeker<Char> &peeker) const { this->next_.peek(peeker); } template<typename Char> void peek_next_(mpl::false_, xpression_peeker<Char> &) const { // no-op } template<std::size_t Width> detail::width get_width_(mpl::size_t<Width>) const { return Width; } detail::width get_width_(unknown_width) const { // Should only be called in contexts where the width is // known to be fixed. return this->Matcher::get_width() + this->next_.get_width(); } }; /////////////////////////////////////////////////////////////////////////////// // make_static // template<typename Matcher> inline static_xpression<Matcher> const make_static(Matcher const &matcher) { return static_xpression<Matcher>(matcher); } template<typename Matcher, typename Next> inline static_xpression<Matcher, Next> const make_static(Matcher const &matcher, Next const &next) { return static_xpression<Matcher, Next>(matcher, next); } /////////////////////////////////////////////////////////////////////////////// // no_next // struct no_next { BOOST_STATIC_CONSTANT(std::size_t, width = 0); BOOST_STATIC_CONSTANT(bool, pure = true); template<typename Char> void link(xpression_linker<Char> &) const { } template<typename Char> void peek(xpression_peeker<Char> &peeker) const { peeker.fail(); } detail::width get_width() const { return 0; } }; /////////////////////////////////////////////////////////////////////////////// // get_mark_number // inline int get_mark_number(basic_mark_tag const &mark) { return proto::value(mark).mark_number_; } }}} // namespace boost::xpressive::detail #endif