// Copyright (c) 2001-2011 Hartmut Kaiser
// Copyright (c) 2010 Bryce Lelbach
//
// 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)
#if !defined(BOOST_SPIRIT_LEX_STATE_SWITCHER_SEP_23_2007_0714PM)
#define BOOST_SPIRIT_LEX_STATE_SWITCHER_SEP_23_2007_0714PM
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/spirit/home/support/info.hpp>
#include <boost/spirit/home/qi/detail/attributes.hpp>
#include <boost/spirit/home/support/common_terminals.hpp>
#include <boost/spirit/home/support/string_traits.hpp>
#include <boost/spirit/home/support/has_semantic_action.hpp>
#include <boost/spirit/home/support/handles_container.hpp>
#include <boost/spirit/home/qi/skip_over.hpp>
#include <boost/spirit/home/qi/domain.hpp>
#include <boost/spirit/home/qi/parser.hpp>
#include <boost/spirit/home/qi/meta_compiler.hpp>
namespace boost { namespace spirit
{
///////////////////////////////////////////////////////////////////////////
// Enablers
///////////////////////////////////////////////////////////////////////////
// enables set_state(s)
template <typename A0>
struct use_terminal<qi::domain
, terminal_ex<tag::set_state, fusion::vector1<A0> >
> : traits::is_string<A0> {};
// enables *lazy* set_state(s)
template <>
struct use_lazy_terminal<
qi::domain, tag::set_state, 1
> : mpl::true_ {};
// enables in_state(s)[p]
template <typename A0>
struct use_directive<qi::domain
, terminal_ex<tag::in_state, fusion::vector1<A0> >
> : traits::is_string<A0> {};
// enables *lazy* in_state(s)[p]
template <>
struct use_lazy_directive<
qi::domain, tag::in_state, 1
> : mpl::true_ {};
}}
namespace boost { namespace spirit { namespace qi
{
#ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
using spirit::set_state;
using spirit::in_state;
#endif
using spirit::set_state_type;
using spirit::in_state_type;
///////////////////////////////////////////////////////////////////////////
namespace detail
{
template <typename Iterator>
inline std::size_t
set_lexer_state(Iterator& it, std::size_t state)
{
return it.set_state(state);
}
template <typename Iterator, typename Char>
inline std::size_t
set_lexer_state(Iterator& it, Char const* statename)
{
std::size_t state = it.map_state(statename);
// If the following assertion fires you probably used the
// set_state(...) or in_state(...)[...] lexer state switcher with
// a lexer state name unknown to the lexer (no token definitions
// have been associated with this lexer state).
BOOST_ASSERT(std::size_t(~0) != state);
return it.set_state(state);
}
}
///////////////////////////////////////////////////////////////////////////
// Parser switching the state of the underlying lexer component.
// This parser gets used for the set_state(...) construct.
///////////////////////////////////////////////////////////////////////////
template <typename State>
struct state_switcher
: primitive_parser<state_switcher<State> >
{
typedef typename
remove_const<typename traits::char_type_of<State>::type>::type
char_type;
typedef std::basic_string<char_type> string_type;
template <typename Context, typename Iterator>
struct attribute
{
typedef unused_type type;
};
state_switcher(char_type const* state)
: state(state) {}
template <typename Iterator, typename Context
, typename Skipper, typename Attribute>
bool parse(Iterator& first, Iterator const& last
, Context& /*context*/, Skipper const& skipper
, Attribute& /*attr*/) const
{
qi::skip_over(first, last, skipper); // always do a pre-skip
// just switch the state and return success
detail::set_lexer_state(first, state.c_str());
return true;
}
template <typename Context>
info what(Context& /*context*/) const
{
return info("set_state");
}
string_type state;
};
///////////////////////////////////////////////////////////////////////////
namespace detail
{
template <typename Iterator>
struct reset_state_on_exit
{
template <typename State>
reset_state_on_exit(Iterator& it_, State state_)
: it(it_)
, state(set_lexer_state(it_, traits::get_c_string(state_)))
{}
~reset_state_on_exit()
{
// reset the state of the underlying lexer instance
set_lexer_state(it, state);
}
Iterator& it;
std::size_t state;
// silence MSVC warning C4512: assignment operator could not be generated
BOOST_DELETED_FUNCTION(reset_state_on_exit& operator= (reset_state_on_exit const&))
};
}
///////////////////////////////////////////////////////////////////////////
// Parser, which switches the state of the underlying lexer component
// for the execution of the embedded sub-parser, switching the state back
// afterwards. This parser gets used for the in_state(...)[p] construct.
///////////////////////////////////////////////////////////////////////////
template <typename Subject, typename State>
struct state_switcher_context
: unary_parser<state_switcher_context<Subject, State> >
{
typedef Subject subject_type;
typedef typename traits::char_type_of<State>::type char_type;
typedef typename remove_const<char_type>::type non_const_char_type;
template <typename Context, typename Iterator>
struct attribute
{
typedef typename
traits::attribute_of<subject_type, Context, Iterator>::type
type;
};
state_switcher_context(Subject const& subject
, typename add_reference<State>::type state)
: subject(subject), state(state) {}
// The following conversion constructors are needed to make the
// in_state_switcher template usable
template <typename String>
state_switcher_context(
state_switcher_context<Subject, String> const& rhs)
: subject(rhs.subject), state(traits::get_c_string(rhs.state)) {}
template <typename Iterator, typename Context
, typename Skipper, typename Attribute>
bool parse(Iterator& first, Iterator const& last
, Context& context, Skipper const& skipper
, Attribute& attr) const
{
qi::skip_over(first, last, skipper); // always do a pre-skip
// the state has to be reset at exit in any case
detail::reset_state_on_exit<Iterator> guard(first, state);
return subject.parse(first, last, context, skipper, attr);
}
template <typename Context>
info what(Context& context) const
{
return info("in_state", subject.what(context));
}
Subject subject;
State state;
// silence MSVC warning C4512: assignment operator could not be generated
BOOST_DELETED_FUNCTION(state_switcher_context& operator= (state_switcher_context const&))
};
///////////////////////////////////////////////////////////////////////////
// Parser generators: make_xxx function (objects)
///////////////////////////////////////////////////////////////////////////
template <typename Modifiers, typename State>
struct make_primitive<terminal_ex<tag::set_state, fusion::vector1<State> >
, Modifiers, typename enable_if<traits::is_string<State> >::type>
{
typedef typename add_const<State>::type const_string;
typedef state_switcher<const_string> result_type;
template <typename Terminal>
result_type operator()(Terminal const& term, unused_type) const
{
return result_type(traits::get_c_string(fusion::at_c<0>(term.args)));
}
};
template <typename State, typename Subject, typename Modifiers>
struct make_directive<terminal_ex<tag::in_state, fusion::vector1<State> >
, Subject, Modifiers>
{
typedef typename add_const<State>::type const_string;
typedef state_switcher_context<Subject, const_string> result_type;
template <typename Terminal>
result_type operator()(Terminal const& term, Subject const& subject
, unused_type) const
{
return result_type(subject, fusion::at_c<0>(term.args));
}
};
}}}
namespace boost { namespace spirit { namespace traits
{
///////////////////////////////////////////////////////////////////////////
template <typename Subject, typename State>
struct has_semantic_action<qi::state_switcher_context<Subject, State> >
: unary_has_semantic_action<Subject> {};
///////////////////////////////////////////////////////////////////////////
template <typename Subject, typename State, typename Attribute
, typename Context, typename Iterator>
struct handles_container<qi::state_switcher_context<Subject, State>
, Attribute, Context, Iterator>
: unary_handles_container<Subject, Attribute, Context, Iterator> {};
}}}
#endif