boost/spirit/home/classic/core/match.hpp
/*=============================================================================
Copyright (c) 1998-2003 Joel de Guzman
http://spirit.sourceforge.net/
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_MATCH_HPP)
#define BOOST_SPIRIT_MATCH_HPP
#include <boost/spirit/home/classic/namespace.hpp>
#include <boost/spirit/home/classic/core/config.hpp>
#include <boost/spirit/home/classic/core/nil.hpp>
#include <boost/call_traits.hpp>
#include <boost/optional.hpp>
#include <boost/spirit/home/classic/core/assert.hpp>
#include <boost/spirit/home/classic/core/safe_bool.hpp>
#include <boost/spirit/home/classic/core/impl/match_attr_traits.ipp>
#include <boost/type_traits/add_const.hpp>
#include <boost/type_traits/add_reference.hpp>
#include <boost/type_traits/conditional.hpp>
#include <boost/type_traits/is_reference.hpp>
namespace boost { namespace spirit {
BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
///////////////////////////////////////////////////////////////////////////
//
// match class
//
// The match holds the result of a parser. A match object evaluates
// to true when a successful match is found, otherwise false. The
// length of the match is the number of characters (or tokens) that
// is successfully matched. This can be queried through its length()
// member function. A negative value means that the match is
// unsucessful.
//
// Each parser may have an associated attribute. This attribute is
// also returned back to the client on a successful parse through
// the match object. The match's value() member function returns the
// match's attribute.
//
// A match attribute is valid:
//
// * on a successful match
// * when its value is set through the value(val) member function
// * if it is assigned or copied from a compatible match object
// (e.g. match<double> from match<int>) with a valid attribute.
//
// The match attribute is undefined:
//
// * on an unsuccessful match
// * when an attempt to copy or assign from another match object
// with an incompatible attribute type (e.g. match<std::string>
// from match<int>).
//
// The member function has_valid_attribute() can be queried to know if
// it is safe to get the match's attribute. The attribute may be set
// through the member function value(v) where v is the new attribute
// value.
//
///////////////////////////////////////////////////////////////////////////
template <typename T = nil_t>
class match : public safe_bool<match<T> >
{
typedef typename
conditional<
is_reference<T>::value
, T
, typename add_reference<
typename add_const<T>::type
>::type
>::type attr_ref_t;
public:
typedef typename boost::optional<T> optional_type;
typedef attr_ref_t ctor_param_t;
typedef attr_ref_t return_t;
typedef T attr_t;
match();
explicit match(std::size_t length);
match(std::size_t length, ctor_param_t val);
bool operator!() const;
std::ptrdiff_t length() const;
bool has_valid_attribute() const;
return_t value() const;
void swap(match& other);
template <typename T2>
match(match<T2> const& other)
: len(other.length()), val()
{
impl::match_attr_traits<T>::copy(val, other);
}
template <typename T2>
match&
operator=(match<T2> const& other)
{
impl::match_attr_traits<T>::assign(val, other);
len = other.length();
return *this;
}
template <typename MatchT>
void
concat(MatchT const& other)
{
BOOST_SPIRIT_ASSERT(*this && other);
len += other.length();
}
template <typename ValueT>
void
value(ValueT const& val_)
{
impl::match_attr_traits<T>::set_value(val, val_, is_reference<T>());
}
bool operator_bool() const
{
return len >= 0;
}
private:
std::ptrdiff_t len;
optional_type val;
};
///////////////////////////////////////////////////////////////////////////
//
// match class specialization for nil_t values
//
///////////////////////////////////////////////////////////////////////////
template <>
class match<nil_t> : public safe_bool<match<nil_t> >
{
public:
typedef nil_t attr_t;
typedef nil_t return_t;
match();
explicit match(std::size_t length);
match(std::size_t length, nil_t);
bool operator!() const;
bool has_valid_attribute() const;
std::ptrdiff_t length() const;
nil_t value() const;
void value(nil_t);
void swap(match& other);
template <typename T>
match(match<T> const& other)
: len(other.length()) {}
template <typename T>
match<>&
operator=(match<T> const& other)
{
len = other.length();
return *this;
}
template <typename T>
void
concat(match<T> const& other)
{
BOOST_SPIRIT_ASSERT(*this && other);
len += other.length();
}
bool operator_bool() const
{
return len >= 0;
}
private:
std::ptrdiff_t len;
};
BOOST_SPIRIT_CLASSIC_NAMESPACE_END
}} // namespace BOOST_SPIRIT_CLASSIC_NS
#endif
#include <boost/spirit/home/classic/core/impl/match.ipp>
