wytp.types.extractors

Class ReadableRecordExtractor

java.lang.Object

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

wytp.types.extractors.ReadableRecordExtractor

All Implemented Interfaces:

TypeExtractor<WyalFile.Type.Record,Object>

public class ReadableRecordExtractor
extends AbstractTypeExtractor<WyalFile.Type.Record>

Responsible for extracting a "readable record" from a given type. A readable record is a conservative approximation of the records described in a given type. Furthermore, it is safe used when reading field values from that type. For example, the type {int f}|{bool f} has a readable record type of {int|bool f}. This is the readable type as, if we were to read field f 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 a record of type {int f}, then writing a boolean value is not permitted.

Not all types have readable record type and, furthermore, care must be exercised for those that do. For example, {int f}|int does not have a readable record type. Likewise, the readable record type for {int f, int g}|{bool f} is {int|bool f, ...}. Finally, negations play an important role in determining the readable record type. For example, {int|null f} & !{int f} generates the readable record type {null f}.

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
ReadableRecordExtractor(wybs.lang.NameResolver resolver, TypeSystem typeSystem)

Method Summary

Modifier and Type	Method and Description
protected WyalFile.Type.Record	construct(WyalFile.Type.Atom type)
protected int	countMatchingFields(WyalFile.FieldDeclaration[] lhsFields, WyalFile.FieldDeclaration[] rhsFields) Count the number of matching fields.
protected int	extractMatchingFields(WyalFile.FieldDeclaration[] lhsFields, WyalFile.FieldDeclaration[] rhsFields, WyalFile.FieldDeclaration[] result) Extract all matching fields (i.e.
protected int	extractNonMatchingFields(WyalFile.FieldDeclaration[] lhsFields, WyalFile.FieldDeclaration[] rhsFields, WyalFile.FieldDeclaration[] result, int index) Extract fields from lhs which do not match any field in the rhs.
protected WyalFile.Type.Record	intersect(WyalFile.Type.Record lhs, WyalFile.Type.Record rhs)
protected WyalFile.Type.Record	subtract(WyalFile.Type.Record lhs, WyalFile.Type.Record rhs)
protected WyalFile.Type.Record	union(WyalFile.Type.Record lhs, WyalFile.Type.Record 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

ReadableRecordExtractor

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

Method Detail

construct

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

Specified by:

construct in class AbstractTypeExtractor<WyalFile.Type.Record>

union

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

Specified by:

union in class AbstractTypeExtractor<WyalFile.Type.Record>

subtract

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

Specified by:

subtract in class AbstractTypeExtractor<WyalFile.Type.Record>

intersect

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

Specified by:

intersect in class AbstractTypeExtractor<WyalFile.Type.Record>

countMatchingFields

protected int countMatchingFields(WyalFile.FieldDeclaration[] lhsFields,
                                  WyalFile.FieldDeclaration[] rhsFields)

Count the number of matching fields. That is, fields with the same name.

Parameters:

lhsFields -

rhsFields -

Returns:

extractMatchingFields

protected int extractMatchingFields(WyalFile.FieldDeclaration[] lhsFields,
                                    WyalFile.FieldDeclaration[] rhsFields,
                                    WyalFile.FieldDeclaration[] result)

Extract all matching fields (i.e. fields with the same name) into the result array.

Parameters:

lhsFields -

rhsFields -

result -

Returns:

extractNonMatchingFields

protected int extractNonMatchingFields(WyalFile.FieldDeclaration[] lhsFields,
                                       WyalFile.FieldDeclaration[] rhsFields,
                                       WyalFile.FieldDeclaration[] result,
                                       int index)

Extract fields from lhs which do not match any field in the rhs. That is, there is no field in the rhs with the same name.

Parameters:

lhsFields -

rhsFields -

result -

index -

Returns: