boost/spirit/home/x3/directive/with.hpp
/*=============================================================================
Copyright (c) 2014 Joel de Guzman
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_SPIRIT_X3_DIRECTIVE_WITH_HPP
#define BOOST_SPIRIT_X3_DIRECTIVE_WITH_HPP
#include <boost/spirit/home/x3/support/unused.hpp>
#include <boost/spirit/home/x3/core/parser.hpp>
namespace boost { namespace spirit { namespace x3
{
///////////////////////////////////////////////////////////////////////////
// with directive injects a value into the context prior to parsing.
///////////////////////////////////////////////////////////////////////////
template <typename Subject, typename Derived, typename T>
struct with_value_holder
: unary_parser<Subject, Derived>
{
typedef unary_parser<Subject, Derived> base_type;
mutable T val;
constexpr with_value_holder(Subject const& subject, T&& val)
: base_type(subject)
, val(std::forward<T>(val)) {}
};
template <typename Subject, typename Derived, typename T>
struct with_value_holder<Subject, Derived, T&>
: unary_parser<Subject, Derived>
{
typedef unary_parser<Subject, Derived> base_type;
T& val;
constexpr with_value_holder(Subject const& subject, T& val)
: base_type(subject)
, val(val) {}
};
template <typename Subject, typename ID, typename T>
struct with_directive
: with_value_holder<Subject, with_directive<Subject, ID, T>, T>
{
typedef with_value_holder<Subject, with_directive<Subject, ID, T>, T> base_type;
static bool const is_pass_through_unary = true;
static bool const handles_container = Subject::handles_container;
typedef Subject subject_type;
constexpr with_directive(Subject const& subject, T&& val)
: base_type(subject, std::forward<T>(val)) {}
template <typename Iterator, typename Context
, typename RContext, typename Attribute>
bool parse(Iterator& first, Iterator const& last
, Context const& context, RContext& rcontext, Attribute& attr) const
{
return this->subject.parse(
first, last
, make_context<ID>(this->val, context)
, rcontext
, attr);
}
};
template <typename ID, typename T>
struct with_gen
{
T&& val;
template <typename Subject>
constexpr with_directive<typename extension::as_parser<Subject>::value_type, ID, T>
operator[](Subject const& subject) const
{
return { as_parser(subject), std::forward<T>(val) };
}
};
template <typename ID, typename T>
constexpr with_gen<ID, T> with(T&& val)
{
return { std::forward<T>(val) };
}
}}}
#endif
