saffron.rel
Interface TypeFactory

All Known Subinterfaces:

OJTypeFactory

All Known Implementing Classes:

OJTypeFactoryImpl, TypeFactoryImpl

public interface TypeFactory

Creates types.

Any implementation of TypeFactory must ensure that types are canonical: two types are equal if and only if they are the same object.

Since:

May 29, 2003

Version:

$Id: //open/saffron/src/main/saffron/rel/TypeFactory.java#3 $

Author:

jhyde

Nested Class Summary

static interface

TypeFactory.FieldInfo Callback which provides enough information to create fields.

Method Summary

Type	createJavaType(Class clazz) Creates a type which encapsulates a Java class.
Type	createJoinType(Type[] types) Creates a cartesian product type.
Type	createProjectType(Type[] types, String[] fieldNames) Creates a type which represents a projection of a set of fields.
Type	createProjectType(TypeFactory.FieldInfo fieldInfo) Creates a type which represents a projection of a set fields, getting the field informatation from a callback.
Type	leastRestrictive(Type[] types) Returns the most general of a set of types (that is, one type to which they can all be cast), or null if conversion is not possible.

Method Detail

createProjectType

public Type createProjectType(Type[] types,
                              String[] fieldNames)

Creates a type which represents a projection of a set of fields.

The return is canonical: if an equivalent type already exists, it is returned.

Parameters:

types - Types of the fields

fieldNames - Names of the fields

Returns:

a type

Pre-condition:

types.length == fieldNames.length

Post-condition:

return != null

createProjectType

public Type createProjectType(TypeFactory.FieldInfo fieldInfo)

Creates a type which represents a projection of a set fields, getting the field informatation from a callback.

createJoinType

public Type createJoinType(Type[] types)

Creates a cartesian product type.

Pre-condition:

types != null, types.length >= 1

leastRestrictive

public Type leastRestrictive(Type[] types)

Returns the most general of a set of types (that is, one type to which they can all be cast), or null if conversion is not possible.

Pre-condition:

types != null, types.length >= 1

createJavaType

public Type createJavaType(Class clazz)

Creates a type which encapsulates a Java class.