wytp.types.extractors

Class ReadableArrayExtractor

java.lang.Object

wytp.types.util.AbstractTypeExtractor<WyalFile.Type.Array>

wytp.types.extractors.ReadableArrayExtractor

All Implemented Interfaces:

TypeExtractor<WyalFile.Type.Array,Object>

public class ReadableArrayExtractor
extends AbstractTypeExtractor<WyalFile.Type.Array>

Responsible for extracting a "readable array" from a given type. A readable array is a conservative approximation of the arrays described in a given type. Furthermore, it is safe used when reading elements from that type. For example, the type (int[])|(bool[]) has a readable array type of (int|bool)[]. This is the readable type as, if we were to read an element from either bound, the return type would be in int|bool. However, we cannot use type for writing as this could be unsafe. For example, if we actually had an array of type int[], then writing a boolean value is not permitted.

Not all types have readable array type and, furthermore, care must be exercised for those that do. For example, (int[])|int does not have a readable array type. Finally, negations play an important role in determining the readable array type. For example, (int|null)[] & !(int[]) generates the readable array type null[].

Author:

David J. Pearce

Nested Class Summary

Nested classes/interfaces inherited from class wytp.types.util.AbstractTypeExtractor

AbstractTypeExtractor.Conjunct, AbstractTypeExtractor.Disjunct, AbstractTypeExtractor.Signed

Field Summary

Fields inherited from class wytp.types.util.AbstractTypeExtractor

resolver, typeSystem

Constructor Summary

Constructors

Constructor and Description
ReadableArrayExtractor(wybs.lang.NameResolver resolver, TypeSystem typeSystem)

Method Summary

Modifier and Type	Method and Description
protected WyalFile.Type.Array	construct(WyalFile.Type.Atom type)
protected WyalFile.Type.Array	intersect(WyalFile.Type.Array lhs, WyalFile.Type.Array rhs)
protected WyalFile.Type.Array	subtract(WyalFile.Type.Array lhs, WyalFile.Type.Array rhs)
protected WyalFile.Type.Array	union(WyalFile.Type.Array lhs, WyalFile.Type.Array rhs)

Methods inherited from class wytp.types.util.AbstractTypeExtractor

construct, construct, extract, intersectionHelper, isVoid, toDisjunctiveNormalForm, toDisjunctiveNormalForm, toDisjunctiveNormalForm, toDisjunctiveNormalForm, toDisjunctiveNormalForm, toDisjunctiveNormalForm, toDisjunctiveNormalForm, toDisjunctiveNormalForm, toDisjunctiveNormalForm, toDisjunctiveNormalForm, unionHelper

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ReadableArrayExtractor

public ReadableArrayExtractor(wybs.lang.NameResolver resolver,
                              TypeSystem typeSystem)

Method Detail

construct

protected WyalFile.Type.Array construct(WyalFile.Type.Atom type)

Specified by:

construct in class AbstractTypeExtractor<WyalFile.Type.Array>

union

protected WyalFile.Type.Array union(WyalFile.Type.Array lhs,
                                    WyalFile.Type.Array rhs)

Specified by:

union in class AbstractTypeExtractor<WyalFile.Type.Array>

subtract

protected WyalFile.Type.Array subtract(WyalFile.Type.Array lhs,
                                       WyalFile.Type.Array rhs)

Specified by:

subtract in class AbstractTypeExtractor<WyalFile.Type.Array>

intersect

protected WyalFile.Type.Array intersect(WyalFile.Type.Array lhs,
                                        WyalFile.Type.Array rhs)

Specified by:

intersect in class AbstractTypeExtractor<WyalFile.Type.Array>