Concept 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

proto_grammar
```
Domain::proto_grammar
```
The grammar to which every expression in this Domain must conform.
proto_generator
```
Domain::proto_generator
```
A Unary Polymorphic Function that accepts expressions in the default domain and emits expressions in this Domain.
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.
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.
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.
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

boost::proto::default_domain