CONCEPT DOMAIN(7)

NAME
Domain

DESCRIPTION

A Domain creates an association between expressions and a so-called generator, which is a function that maps an expression in the default domain to an equivalent expression in this Domain. It also associates an expression with a grammar, to which all expressions within this Domain must conform.

ASSOCIATED TYPES

    &#8226; proto_grammar

    Domain::proto_grammar
    The grammar to which every expression in this Domain must conform.

    &#8226; proto_generator

    Domain::proto_generator
    A Unary Polymorphic Function that accepts expressions in the default domain and emits expressions in this Domain.

    &#8226; proto_super_domain

    Domain::proto_super_domain
    The Domain that is a super-domain of this domain, if any such domain exists. If not, it is some unspecified type.

    &#8226; result_type

    boost::result_of<Domain(Expr)>::type
    The type of the result of applying proto_generator to the specified expression type. The result is required to model Expr. The domain type associated with result_type (result_type::proto_domain) is required to be the same type as this Domain.

    &#8226; as_expr_result_type

    Domain::as_expr<Object>::result_type
    The result of converting some type to a Proto expression type in this domain. This is used, for instance, when calculating the type of a variable to hold a Proto expression. as_expr_result_type models Expr.

    &#8226; as_child_result_type

    Domain::as_child<Object>::result_type
    The result of converting some type to a Proto expression type in this domain. This is used, for instance, to compute the type of an object suitable for storage as a child in an expression tree. as_child_result_type models Expr.

NOTATION

Domain
    A type playing the role of domain-type in the Domain concept.

Expr
    A type playing the role of expression-type in the Domain concept.

Object
    A type playing the role of object-type in the Domain concept.

d
    Object of type Domain

e
    Object of type Expr

o
    Object of type Object

VALID EXPRESSIONS
Name | Expression | Type | Semantics
Apply Generator | d(e) | result_type | The result of applying proto_generator to the specified expression.
As Expression | Domain::as_expr< Object >()(o) | as_expr_result_type | The result of converting some object to a Proto expression in this domain. It returns a Proto expression object that is suitable for storage in a variable. It should return a new object, which may be a copy of the object passed in.
As Child | Domain::as_child< Object >()(o) | as_child_result_type | The result of converting some object to a Proto expression in this domain. It returns an object suitable for storage as a child in an expression tree, which may simply be a reference to the object passed in.

MODELS

    &#8226; boost::proto::default_domain