#include <boost/config.hpp>
#include <boost/preprocessor/cat.hpp>
#include <boost/tti/gen/has_type_gen.hpp>
#include <boost/tti/gen/namespace_gen.hpp>
#include <boost/tti/detail/dtype.hpp>
#include <boost/tti/detail/ddeftype.hpp>

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Macros
#define	BOOST_TTI_TRAIT_HAS_TYPE(trait, name)
	BOOST_TTI_TRAIT_HAS_TYPE is a macro which expands to a metafunction. More...

#define	BOOST_TTI_HAS_TYPE(name)
	BOOST_TTI_HAS_TYPE is a macro which expands to a metafunction. More...

Macro Definition Documentation

#define BOOST_TTI_HAS_TYPE ( name )

Value:

BOOST_TTI_TRAIT_HAS_TYPE \
  ( \
  BOOST_TTI_HAS_TYPE_GEN(name), \
  name \
  ) \

BOOST_TTI_HAS_TYPE is a macro which expands to a metafunction.

The metafunction tests whether an inner type with a particular name exists and, optionally, whether a lambda expression invoked with the inner type is true or not.

name = the name of the inner type.

generates a metafunction called "has_type_'name'" where 'name' is the macro parameter.

      template<class BOOST_TTI_TP_T,class BOOST_TTI_TP_U>
      struct has_type_'name'
        {
        static const value = unspecified;
        typedef mpl::bool_<true-or-false> type;
        };

      The metafunction types and return:

        BOOST_TTI_TP_T = the enclosing type in which to look for our 'name'.

        BOOST_TTI_TP_U = (optional) An optional template parameter, defaulting to a marker type.
                           If specified it is an MPL lambda expression which is invoked 
                           with the inner type found and must return a constant boolean 
                           value.

        returns = 'value' depends on whether or not the optional BOOST_TTI_TP_U is specified.

                  If BOOST_TTI_TP_U is not specified, then 'value' is true if the 'name' type 
                  exists within the enclosing type BOOST_TTI_TP_T; otherwise 'value' is false.

                  If BOOST_TTI_TP_U is specified , then 'value' is true if the 'name' type exists 
                  within the enclosing type BOOST_TTI_TP_T and the lambda expression as specified 
                  by BOOST_TTI_TP_U, invoked by passing the actual inner type of 'name', returns 
                  a 'value' of true; otherwise 'value' is false.

                  The action taken with BOOST_TTI_TP_U occurs only when the 'name' type exists 
                  within the enclosing type BOOST_TTI_TP_T.

Example usage:

BOOST_TTI_HAS_TYPE(MyType) generates the metafunction has_type_MyType in the current scope to look for an inner type called MyType.

has_type_MyType<EnclosingType>::value is true if MyType is an inner type of EnclosingType, otherwise false.

has_type_MyType<EnclosingType,ALambdaExpression>::value is true if MyType is an inner type of EnclosingType and invoking ALambdaExpression with the inner type returns a value of true, otherwise false.

A popular use of the optional MPL lambda expression is to check whether the type found is the same as another type, when the type found is a typedef. In that case our example would be:

has_type_MyType<EnclosingType,boost::is_same<_,SomeOtherType> >::value is true if MyType is an inner type of EnclosingType and is the same type as SomeOtherType.

#define BOOST_TTI_TRAIT_HAS_TYPE	(	trait,
		name
	)

Value:

BOOST_TTI_DETAIL_TRAIT_HAS_TYPE(trait,name) \
  template \
    < \
    class BOOST_TTI_TP_T, \
    class BOOST_TTI_TP_U = BOOST_TTI_NAMESPACE::detail::deftype \
    > \
  struct trait \
    { \
    typedef typename \
    BOOST_PP_CAT(trait,_detail_type)<BOOST_TTI_TP_T,BOOST_TTI_TP_U>::type type; \
    BOOST_STATIC_CONSTANT(bool,value=type::value); \
    }; \

BOOST_TTI_TRAIT_HAS_TYPE is a macro which expands to a metafunction.

The metafunction tests whether an inner type with a particular name exists and, optionally, whether a lambda expression invoked with the inner type is true or not.

trait = the name of the metafunction within the tti namespace.

name = the name of the inner type.

generates a metafunction called "trait" where 'trait' is the macro parameter.

      template<class BOOST_TTI_TP_T,class BOOST_TTI_TP_U>
      struct trait
        {
        static const value = unspecified;
        typedef mpl::bool_<true-or-false> type;
        };

      The metafunction types and return:

        BOOST_TTI_TP_T = the enclosing type in which to look for our 'name'.

        BOOST_TTI_TP_U = (optional) An optional template parameter, defaulting to a marker type.
                           If specified it is an MPL lambda expression which is invoked 
                           with the inner type found and must return a constant boolean 
                           value.

        returns = 'value' depends on whether or not the optional BOOST_TTI_TP_U is specified.

                  If BOOST_TTI_TP_U is not specified, then 'value' is true if the 'name' type 
                  exists within the enclosing type BOOST_TTI_TP_T; otherwise 'value' is false.

                  If BOOST_TTI_TP_U is specified , then 'value' is true if the 'name' type exists 
                  within the enclosing type BOOST_TTI_TP_T and the lambda expression as specified 
                  by BOOST_TTI_TP_U, invoked by passing the actual inner type of 'name', returns 
                  a 'value' of true; otherwise 'value' is false.

                  The action taken with BOOST_TTI_TP_U occurs only when the 'name' type exists 
                  within the enclosing type BOOST_TTI_TP_T.

Example usage:

BOOST_TTI_TRAIT_HAS_TYPE(LookFor,MyType) generates the metafunction LookFor in the current scope to look for an inner type called MyType.

LookFor<EnclosingType>::value is true if MyType is an inner type of EnclosingType, otherwise false.

LookFor<EnclosingType,ALambdaExpression>::value is true if MyType is an inner type of EnclosingType and invoking ALambdaExpression with the inner type returns a value of true, otherwise false.

A popular use of the optional MPL lambda expression is to check whether the type found is the same as another type, when the type found is a typedef. In that case our example would be:

LookFor<EnclosingType,boost::is_same<_,SomeOtherType> >::value is true if MyType is an inner type of EnclosingType and is the same type as SomeOtherType.

Macros

Macro Definition Documentation