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574 lines
21 KiB
574 lines
21 KiB
/*============================================================================= |
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Copyright (c) 2003 Hartmut Kaiser |
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http://spirit.sourceforge.net/ |
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Use, modification and distribution is subject to the Boost Software |
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License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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http://www.boost.org/LICENSE_1_0.txt) |
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=============================================================================*/ |
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#ifndef BOOST_SPIRIT_SWITCH_IPP |
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#define BOOST_SPIRIT_SWITCH_IPP |
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#include <boost/mpl/if.hpp> |
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#include <boost/type_traits/is_same.hpp> |
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#include <boost/static_assert.hpp> |
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#include <boost/preprocessor/cat.hpp> |
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#include <boost/preprocessor/inc.hpp> |
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#include <boost/preprocessor/repeat.hpp> |
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#include <boost/preprocessor/repeat_from_to.hpp> |
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#include <boost/spirit/home/classic/core/parser.hpp> |
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#include <boost/spirit/home/classic/core/primitives/primitives.hpp> |
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#include <boost/spirit/home/classic/core/composite/composite.hpp> |
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#include <boost/spirit/home/classic/meta/as_parser.hpp> |
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#include <boost/spirit/home/classic/phoenix/actor.hpp> |
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#include <boost/spirit/home/classic/phoenix/tuples.hpp> |
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/////////////////////////////////////////////////////////////////////////////// |
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namespace boost { namespace spirit { |
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BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN |
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// forward declaration |
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template <int N, typename ParserT, bool IsDefault> struct case_parser; |
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/////////////////////////////////////////////////////////////////////////////// |
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namespace impl { |
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/////////////////////////////////////////////////////////////////////////////// |
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// parse helper functions |
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template <typename ParserT, typename ScannerT> |
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inline typename parser_result<ParserT, ScannerT>::type |
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delegate_parse(ParserT const &p, ScannerT const &scan, |
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typename ScannerT::iterator_t const save) |
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{ |
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typedef typename parser_result<ParserT, ScannerT>::type result_t; |
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result_t result (p.subject().parse(scan)); |
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if (!result) |
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scan.first = save; |
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return result; |
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} |
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/////////////////////////////////////////////////////////////////////////////// |
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// General default case handling (no default_p case branch given). |
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// First try to match the current parser node (if the condition value is |
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// matched) and, if that fails, return a no_match |
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template <int N, bool IsDefault, bool HasDefault> |
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struct default_delegate_parse { |
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template < |
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typename ParserT, typename DefaultT, |
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typename ValueT, typename ScannerT |
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> |
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static typename parser_result<ParserT, ScannerT>::type |
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parse (ValueT const &value, ParserT const &p, DefaultT const &, |
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ScannerT const &scan, typename ScannerT::iterator_t const save) |
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{ |
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if (value == N) |
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return delegate_parse(p, scan, save); |
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return scan.no_match(); |
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} |
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}; |
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// The current case parser node is the default parser. |
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// Ignore the given case value and try to match the given default parser. |
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template <int N, bool HasDefault> |
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struct default_delegate_parse<N, true, HasDefault> { |
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template < |
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typename ParserT, typename DefaultT, |
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typename ValueT, typename ScannerT |
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> |
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static typename parser_result<ParserT, ScannerT>::type |
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parse (ValueT const& /*value*/, ParserT const &, DefaultT const &d, |
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ScannerT const &scan, typename ScannerT::iterator_t const save) |
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{ |
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// Since there is a default_p case branch defined, the corresponding |
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// parser shouldn't be the nothing_parser |
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BOOST_STATIC_ASSERT((!boost::is_same<DefaultT, nothing_parser>::value)); |
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return delegate_parse(d, scan, save); |
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} |
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}; |
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// The current case parser node is not the default parser, but there is a |
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// default_p branch given inside the switch_p parser. |
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// First try to match the current parser node (if the condition value is |
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// matched) and, if that fails, match the given default_p parser. |
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template <int N> |
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struct default_delegate_parse<N, false, true> { |
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template < |
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typename ParserT, typename DefaultT, |
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typename ValueT, typename ScannerT |
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> |
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static typename parser_result<ParserT, ScannerT>::type |
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parse (ValueT const &value, ParserT const &p, DefaultT const &d, |
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ScannerT const &scan, typename ScannerT::iterator_t const save) |
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{ |
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// Since there is a default_p case branch defined, the corresponding |
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// parser shouldn't be the nothing_parser |
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BOOST_STATIC_ASSERT((!boost::is_same<DefaultT, nothing_parser>::value)); |
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if (value == N) |
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return delegate_parse(p, scan, save); |
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return delegate_parse(d, scan, save); |
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} |
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}; |
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/////////////////////////////////////////////////////////////////////////////// |
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// Look through the case parser chain to test, if there is a default case |
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// branch defined (returned by 'value'). |
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template <typename CaseT, bool IsSimple = CaseT::is_simple> |
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struct default_case; |
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//////////////////////////////////////// |
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template <typename ResultT, bool IsDefault> |
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struct get_default_parser { |
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template <typename ParserT> |
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static ResultT |
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get(parser<ParserT> const &p) |
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{ |
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return default_case<typename ParserT::derived_t::left_t>:: |
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get(p.derived().left()); |
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} |
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}; |
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template <typename ResultT> |
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struct get_default_parser<ResultT, true> { |
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template <typename ParserT> |
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static ResultT |
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get(parser<ParserT> const &p) { return p.derived().right(); } |
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}; |
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//////////////////////////////////////// |
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template <typename CaseT, bool IsSimple> |
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struct default_case { |
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// The 'value' constant is true, if the current case_parser or one of its |
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// left siblings is a default_p generated case_parser. |
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BOOST_STATIC_CONSTANT(bool, value = |
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(CaseT::is_default || default_case<typename CaseT::left_t>::value)); |
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// The 'is_epsilon' constant is true, if the current case_parser or one of |
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// its left siblings is a default_p generated parser with an attached |
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// epsilon_p (this is generated by the plain default_p). |
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BOOST_STATIC_CONSTANT(bool, is_epsilon = ( |
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(CaseT::is_default && CaseT::is_epsilon) || |
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default_case<typename CaseT::left_t>::is_epsilon |
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)); |
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// The computed 'type' represents the type of the default case branch |
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// parser (if there is one) or nothing_parser (if there isn't any default |
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// case branch). |
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typedef typename boost::mpl::if_c< |
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CaseT::is_default, typename CaseT::right_embed_t, |
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typename default_case<typename CaseT::left_t>::type |
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>::type type; |
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// The get function returns the parser attached to the default case branch |
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// (if there is one) or an instance of a nothing_parser (if there isn't |
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// any default case branch). |
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template <typename ParserT> |
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static type |
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get(parser<ParserT> const &p) |
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{ return get_default_parser<type, CaseT::is_default>::get(p); } |
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}; |
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//////////////////////////////////////// |
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template <typename ResultT, bool IsDefault> |
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struct get_default_parser_simple { |
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template <typename ParserT> |
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static ResultT |
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get(parser<ParserT> const &p) { return p.derived(); } |
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}; |
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template <typename ResultT> |
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struct get_default_parser_simple<ResultT, false> { |
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template <typename ParserT> |
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static nothing_parser |
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get(parser<ParserT> const &) { return nothing_p; } |
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}; |
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//////////////////////////////////////// |
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// Specialization of the default_case template for the last (leftmost) element |
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// of the case parser chain. |
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template <typename CaseT> |
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struct default_case<CaseT, true> { |
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// The 'value' and 'is_epsilon' constant, the 'type' type and the function |
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// 'get' are described above. |
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BOOST_STATIC_CONSTANT(bool, value = CaseT::is_default); |
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BOOST_STATIC_CONSTANT(bool, is_epsilon = ( |
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CaseT::is_default && CaseT::is_epsilon |
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)); |
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typedef typename boost::mpl::if_c< |
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CaseT::is_default, CaseT, nothing_parser |
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>::type type; |
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template <typename ParserT> |
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static type |
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get(parser<ParserT> const &p) |
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{ return get_default_parser_simple<type, value>::get(p); } |
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}; |
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/////////////////////////////////////////////////////////////////////////////// |
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// The case_chain template calculates recursivly the depth of the left |
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// subchain of the given case branch node. |
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template <typename CaseT, bool IsSimple = CaseT::is_simple> |
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struct case_chain { |
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BOOST_STATIC_CONSTANT(int, depth = ( |
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case_chain<typename CaseT::left_t>::depth + 1 |
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)); |
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}; |
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template <typename CaseT> |
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struct case_chain<CaseT, true> { |
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BOOST_STATIC_CONSTANT(int, depth = 0); |
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}; |
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/////////////////////////////////////////////////////////////////////////////// |
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// The chain_parser template is used to extract the type and the instance of |
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// a left or a right parser, burried arbitrary deep inside the case parser |
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// chain. |
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template <int Depth, typename CaseT> |
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struct chain_parser { |
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typedef typename CaseT::left_t our_left_t; |
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typedef typename chain_parser<Depth-1, our_left_t>::left_t left_t; |
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typedef typename chain_parser<Depth-1, our_left_t>::right_t right_t; |
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static left_t |
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left(CaseT const &p) |
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{ return chain_parser<Depth-1, our_left_t>::left(p.left()); } |
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static right_t |
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right(CaseT const &p) |
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{ return chain_parser<Depth-1, our_left_t>::right(p.left()); } |
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}; |
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template <typename CaseT> |
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struct chain_parser<1, CaseT> { |
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typedef typename CaseT::left_t left_t; |
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typedef typename CaseT::right_t right_t; |
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static left_t left(CaseT const &p) { return p.left(); } |
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static right_t right(CaseT const &p) { return p.right(); } |
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}; |
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template <typename CaseT> |
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struct chain_parser<0, CaseT>; // shouldn't be instantiated |
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/////////////////////////////////////////////////////////////////////////////// |
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// Type computing meta function for calculating the type of the return value |
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// of the used conditional switch expression |
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template <typename TargetT, typename ScannerT> |
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struct condition_result { |
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typedef typename TargetT::template result<ScannerT>::type type; |
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}; |
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/////////////////////////////////////////////////////////////////////////////// |
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template <typename LeftT, typename RightT, bool IsDefault> |
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struct compound_case_parser |
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: public binary<LeftT, RightT, |
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parser<compound_case_parser<LeftT, RightT, IsDefault> > > |
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{ |
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typedef compound_case_parser<LeftT, RightT, IsDefault> self_t; |
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typedef binary_parser_category parser_category_t; |
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typedef binary<LeftT, RightT, parser<self_t> > base_t; |
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BOOST_STATIC_CONSTANT(int, value = RightT::value); |
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BOOST_STATIC_CONSTANT(bool, is_default = IsDefault); |
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BOOST_STATIC_CONSTANT(bool, is_simple = false); |
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BOOST_STATIC_CONSTANT(bool, is_epsilon = ( |
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is_default && |
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boost::is_same<typename RightT::subject_t, epsilon_parser>::value |
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)); |
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compound_case_parser(parser<LeftT> const &lhs, parser<RightT> const &rhs) |
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: base_t(lhs.derived(), rhs.derived()) |
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{} |
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template <typename ScannerT> |
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struct result |
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{ |
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typedef typename match_result<ScannerT, nil_t>::type type; |
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}; |
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template <typename ScannerT, typename CondT> |
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typename parser_result<self_t, ScannerT>::type |
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parse(ScannerT const& scan, CondT const &cond) const; |
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template <int N1, typename ParserT1, bool IsDefault1> |
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compound_case_parser< |
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self_t, case_parser<N1, ParserT1, IsDefault1>, IsDefault1 |
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> |
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operator, (case_parser<N1, ParserT1, IsDefault1> const &p) const |
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{ |
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// If the following compile time assertion fires, you've probably used |
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// more than one default_p case inside the switch_p parser construct. |
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BOOST_STATIC_ASSERT(!default_case<self_t>::value || !IsDefault1); |
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// If this compile time assertion fires, you've probably want to use |
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// more case_p/default_p case branches, than possible. |
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BOOST_STATIC_ASSERT( |
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case_chain<self_t>::depth < BOOST_SPIRIT_SWITCH_CASE_LIMIT |
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); |
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typedef case_parser<N1, ParserT1, IsDefault1> right_t; |
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return compound_case_parser<self_t, right_t, IsDefault1>(*this, p); |
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} |
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}; |
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/////////////////////////////////////////////////////////////////////////////// |
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// The parse_switch::do_ functions dispatch to the correct parser, which is |
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// selected through the given conditional switch value. |
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template <int Value, int Depth, bool IsDefault> |
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struct parse_switch; |
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/////////////////////////////////////////////////////////////////////////////// |
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// |
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// The following generates a couple of parse_switch template specializations |
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// with an increasing number of handled case branches (for 1..N). |
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// |
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// template <int Value, bool IsDefault> |
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// struct parse_switch<Value, N, IsDefault> { |
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// |
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// template <typename ParserT, typename ScannerT> |
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// static typename parser_result<ParserT, ScannerT>::type |
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// do_(ParserT const &p, ScannerT const &scan, long cond_value, |
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// typename ScannerT::iterator_t const &save) |
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// { |
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// typedef ParserT left_t0; |
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// typedef typename left_t0::left left_t1; |
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// ... |
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// |
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// switch (cond_value) { |
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// case left_tN::value: |
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// return delegate_parse(chain_parser< |
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// case_chain<ParserT>::depth, ParserT |
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// >::left(p), scan, save); |
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// ... |
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// case left_t1::value: |
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// return delegate_parse(chain_parser< |
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// 1, left_t1 |
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// >::right(p.left()), scan, save); |
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// |
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// case left_t0::value: |
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// default: |
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// typedef default_case<ParserT> default_t; |
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// typedef default_delegate_parse< |
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// Value, IsDefault, default_t::value> |
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// default_parse_t; |
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// |
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// return default_parse_t::parse(cond_value, p.right(), |
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// default_t::get(p), scan, save); |
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// } |
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// } |
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// }; |
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// |
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/////////////////////////////////////////////////////////////////////////////// |
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#define BOOST_SPIRIT_PARSE_SWITCH_TYPEDEFS(z, N, _) \ |
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typedef typename BOOST_PP_CAT(left_t, N)::left_t \ |
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BOOST_PP_CAT(left_t, BOOST_PP_INC(N)); \ |
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/**/ |
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#define BOOST_SPIRIT_PARSE_SWITCH_CASES(z, N, _) \ |
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case (long)(BOOST_PP_CAT(left_t, N)::value): \ |
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return delegate_parse(chain_parser<N, left_t1>::right(p.left()), \ |
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scan, save); \ |
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/**/ |
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#define BOOST_SPIRIT_PARSE_SWITCHES(z, N, _) \ |
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template <int Value, bool IsDefault> \ |
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struct parse_switch<Value, BOOST_PP_INC(N), IsDefault> { \ |
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\ |
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template <typename ParserT, typename ScannerT> \ |
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static typename parser_result<ParserT, ScannerT>::type \ |
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do_(ParserT const &p, ScannerT const &scan, long cond_value, \ |
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typename ScannerT::iterator_t const &save) \ |
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{ \ |
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typedef ParserT left_t0; \ |
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BOOST_PP_REPEAT_FROM_TO_ ## z(0, BOOST_PP_INC(N), \ |
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BOOST_SPIRIT_PARSE_SWITCH_TYPEDEFS, _) \ |
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\ |
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switch (cond_value) { \ |
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case (long)(BOOST_PP_CAT(left_t, BOOST_PP_INC(N))::value): \ |
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return delegate_parse( \ |
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chain_parser< \ |
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case_chain<ParserT>::depth, ParserT \ |
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>::left(p), scan, save); \ |
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\ |
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BOOST_PP_REPEAT_FROM_TO_ ## z(1, BOOST_PP_INC(N), \ |
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BOOST_SPIRIT_PARSE_SWITCH_CASES, _) \ |
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\ |
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case (long)(left_t0::value): \ |
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default: \ |
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typedef default_case<ParserT> default_t; \ |
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typedef \ |
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default_delegate_parse<Value, IsDefault, default_t::value> \ |
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default_parse_t; \ |
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\ |
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return default_parse_t::parse(cond_value, p.right(), \ |
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default_t::get(p), scan, save); \ |
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} \ |
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} \ |
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}; \ |
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/**/ |
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BOOST_PP_REPEAT(BOOST_PP_DEC(BOOST_SPIRIT_SWITCH_CASE_LIMIT), |
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BOOST_SPIRIT_PARSE_SWITCHES, _) |
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#undef BOOST_SPIRIT_PARSE_SWITCH_TYPEDEFS |
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#undef BOOST_SPIRIT_PARSE_SWITCH_CASES |
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#undef BOOST_SPIRIT_PARSE_SWITCHES |
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/////////////////////////////////////////////////////////////////////////////// |
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template <typename LeftT, typename RightT, bool IsDefault> |
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template <typename ScannerT, typename CondT> |
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inline typename parser_result< |
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compound_case_parser<LeftT, RightT, IsDefault>, ScannerT |
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>::type |
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compound_case_parser<LeftT, RightT, IsDefault>:: |
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parse(ScannerT const& scan, CondT const &cond) const |
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{ |
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scan.at_end(); // allow skipper to take effect |
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return parse_switch<value, case_chain<self_t>::depth, is_default>:: |
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do_(*this, scan, cond(scan), scan.first); |
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} |
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/////////////////////////////////////////////////////////////////////////////// |
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// The switch condition is to be evaluated from a parser result value. |
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template <typename ParserT> |
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struct cond_functor { |
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typedef cond_functor<ParserT> self_t; |
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cond_functor(ParserT const &p_) |
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: p(p_) |
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{} |
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template <typename ScannerT> |
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struct result |
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{ |
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typedef typename parser_result<ParserT, ScannerT>::type::attr_t type; |
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}; |
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template <typename ScannerT> |
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typename condition_result<self_t, ScannerT>::type |
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operator()(ScannerT const &scan) const |
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{ |
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typedef typename parser_result<ParserT, ScannerT>::type result_t; |
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typedef typename result_t::attr_t attr_t; |
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result_t result(p.parse(scan)); |
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return !result ? attr_t() : result.value(); |
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} |
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typename ParserT::embed_t p; |
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}; |
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template <typename ParserT> |
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struct make_cond_functor { |
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typedef as_parser<ParserT> as_parser_t; |
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static cond_functor<typename as_parser_t::type> |
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do_(ParserT const &cond) |
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{ |
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return cond_functor<typename as_parser_t::type>( |
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as_parser_t::convert(cond)); |
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} |
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}; |
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/////////////////////////////////////////////////////////////////////////////// |
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// The switch condition is to be evaluated from a phoenix actor |
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template <typename ActorT> |
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struct cond_actor { |
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typedef cond_actor<ActorT> self_t; |
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cond_actor(ActorT const &actor_) |
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: actor(actor_) |
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{} |
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template <typename ScannerT> |
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struct result |
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{ |
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typedef typename ::phoenix::actor_result<ActorT, ::phoenix::tuple<> >::type |
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type; |
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}; |
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template <typename ScannerT> |
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typename condition_result<self_t, ScannerT>::type |
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operator()(ScannerT const& /*scan*/) const |
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{ |
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return actor(); |
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} |
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ActorT const &actor; |
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}; |
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template <typename ActorT> |
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struct make_cond_functor< ::phoenix::actor<ActorT> > { |
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static cond_actor< ::phoenix::actor<ActorT> > |
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do_(::phoenix::actor<ActorT> const &actor) |
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{ |
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return cond_actor< ::phoenix::actor<ActorT> >(actor); |
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} |
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}; |
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/////////////////////////////////////////////////////////////////////////////// |
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// The switch condition is to be taken directly from the input stream |
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struct get_next_token_cond { |
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typedef get_next_token_cond self_t; |
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template <typename ScannerT> |
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struct result |
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{ |
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typedef typename ScannerT::value_t type; |
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}; |
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template <typename ScannerT> |
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typename condition_result<self_t, ScannerT>::type |
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operator()(ScannerT const &scan) const |
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{ |
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typename ScannerT::value_t val(*scan); |
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++scan.first; |
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return val; |
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} |
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}; |
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template <> |
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struct make_cond_functor<get_next_token_cond> { |
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static get_next_token_cond |
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do_(get_next_token_cond const &cond) |
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{ |
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return cond; |
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} |
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}; |
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/////////////////////////////////////////////////////////////////////////////// |
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} // namespace impl |
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BOOST_SPIRIT_CLASSIC_NAMESPACE_END |
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}} // namespace boost::spirit |
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#endif // BOOST_SPIRIT_SWITCH_IPP
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