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Sprout/sprout/weed/parser/directive/omit.hpp
2017-07-29 14:20:01 +09:00

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2.9 KiB
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/*=============================================================================
Copyright (c) 2011-2017 Bolero MURAKAMI
https://github.com/bolero-MURAKAMI/Sprout
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 SPROUT_WEED_PARSER_DIRECTIVE_OMIT_HPP
#define SPROUT_WEED_PARSER_DIRECTIVE_OMIT_HPP
#include <sprout/config.hpp>
#include <sprout/workaround/std/cstddef.hpp>
#include <sprout/type_traits/identity.hpp>
#include <sprout/weed/unused.hpp>
#include <sprout/weed/parser_result.hpp>
#include <sprout/weed/expr/make_terminal_or_expr.hpp>
#include <sprout/weed/expr/eval.hpp>
#include <sprout/weed/parser/parser_base.hpp>
#include <sprout/weed/traits/expr/terminal_or_expr_of.hpp>
#include <sprout/weed/traits/parser/attribute_of.hpp>
namespace sprout {
namespace weed {
//
// omit_p
//
template<typename Parser>
struct omit_p
: public sprout::weed::parser_base
{
public:
template<typename Context, typename Iterator>
struct attribute
: public sprout::identity<sprout::weed::unused>
{};
template<typename Context, typename Iterator>
struct result
: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
{};
private:
typedef typename sprout::weed::traits::terminal_or_expr_of<Parser>::type expr_type;
private:
expr_type expr_;
private:
template<typename Context, typename Iterator, typename Result>
SPROUT_CONSTEXPR typename result<Context, Iterator>::type call(
Iterator first,
Result const& res
) const
{
typedef typename result<Context, Iterator>::type result_type;
typedef typename attribute<Context, Iterator>::type attribute_type;
return res.success()
? result_type(true, res.current(), attribute_type())
: result_type(false, first, attribute_type())
;
}
public:
SPROUT_CONSTEXPR omit_p() SPROUT_DEFAULTED_DEFAULT_CONSTRUCTOR_DECL
explicit SPROUT_CONSTEXPR omit_p(
Parser const& p
)
: expr_(sprout::weed::make_terminal_or_expr(p))
{}
template<typename Context, typename Iterator>
SPROUT_CONSTEXPR typename result<Context, Iterator>::type operator()(
Iterator first, Iterator,
Context const& ctx
) const
{
return call<Context>(first, sprout::weed::eval(expr_, ctx));
}
};
//
// omit_d
//
struct omit_d {
public:
template<typename Parser>
SPROUT_CONSTEXPR sprout::weed::omit_p<Parser> operator[](Parser const& p) const {
return sprout::weed::omit_p<Parser>(p);
}
};
//
// omit
//
SPROUT_CONSTEXPR sprout::weed::omit_d omit = sprout::weed::omit_d();
} // namespace weed
} // namespace sprout
#endif // #ifndef SPROUT_WEED_PARSER_DIRECTIVE_OMIT_HPP