wytp.types

Interface TypeRewriter

All Known Implementing Classes:

AbstractTypeRewriter, StdTypeRewriter

public interface TypeRewriter

Responsible for rewriting a given type in some way whilst maintaining semantic equivalence. Often (though not exclusively) this is used for simplifying types. For example, int|int could be simplfiied to int. Type simplification is necessary, for example, to prevent infinite loops in some operations (e.g. type extraction). Type simplification is also useful in making generated types easier to read.

Type simplification can be performed over a range of constructs. The following highlights some examples:

• Negations. For example, !!int can be rewritten to int. Likewise, !({int f}|int) can be rewritten to (!{int f})|(!int).
• Unions. For example, int|null|int can be rewritten to int|null. Likewise, {int|null f} can be rewritten to {int f}|{null f}.
• Intersections. For example, int&int can be rewritten to int. Likewise, {int|null f}&{int f} can be rewritten to {int f}.

This interface does not specify what rewrites will be applied. It only provides a concept of type simplification in abstract sense. Specific implementations of this interface will choose what rules to apply based on their own use case (e.g. for internal algorithms, for human readability, etc).

Author:

David J. Pearce

Method Summary

Modifier and Type	Method and Description
WyalFile.Type	rewrite(WyalFile.Type type) Apply the rewrite rules to the given type producing a potentially updated type.

Method Detail

rewrite

WyalFile.Type rewrite(WyalFile.Type type)

Apply the rewrite rules to the given type producing a potentially updated type. If no rewrites are applied, then the original Type object should be returned intact.

Parameters:

type - The type to be rewritten

Returns: