Changes between Initial Version and Version 1 of References

Timestamp:

03/15/16 15:10:00 (10 years ago)

Author:

zmanchun

Comment:

--

References

@@ +1 @@
+= Thoughts on references =
+
+Create interfaces:
+* `ReferenceExpression extends SymbolicExpression`
+* `NTReferenceExpression extends ReferenceExpression` for non-trivial references, i.e., references to a tuple component, array element, or union member, or an "offset reference"
+* `ArrayElementReference extends NTReferenceExpression`
+* `TupleComponentReference extends NTReferenceExpression`
+* `UnionMemberReference extends NTReferenceExpression`
+* `OffsetReference extends NTReferenceExpression`
+
+Interface:
+
+The following methods can go in `ReferenceExpression`:
+
+{{{
+/** Is this the null reference? */
+boolean isNullReference();
+
+/** Is this the identity reference? */
+boolean isIdentityReference();
+
+/** Is this an array element reference? */
+boolean isArrayElementReference();
+
+/** Is this a tuple component reference? */
+boolean isTupleComponentReference();
+
+/** Is this a union element reference? */
+boolean isUnionMemberReference();
+
+/** Is this an "offset reference" ? */
+boolean isOffsetReference();
+}}}
+
+The following methods can go in `NTReferenceExpression`:
+
+{{{
+/** As this is a reference to an array element, tuple component, union member, 
+ * or an offset reference, returns the reference to the parent,
+ * i.e., the array, tuple, union, or the  other reference, resp.
+ReferenceExpression getParent();
+}}}
+
+In `ArrayElementReference`:
+{{{
+NumericExpression getIndex();
+}}}
+
+In `TupleComponentReference`:
+{{{
+IntObject getIndex();
+}}}
+
+In `UnionMemberReference`:
+{{{
+IntObject getIndex();
+}}}
+
+In `OffsetReference`:
+{{{
+NumericExpression getOffset();
+}}}
+
+
+The following can go in `SymbolicUniverse`:
+
+{{{
+/** Returns the type of all reference expressions. */
+SymbolicType referenceType();
+
+/** Returns the "null reference", a symbolic expression of reference type which is
+ * not equal to a reference value returned by
+ * any of the other methods, and which cannot be dereferenced. */
+ReferenceExpression nullReference();
+
+/** Given a reference and a value, returns the sub-expression of value specified by the reference.
+ * Throws exception if the reference is not of the correct form for the type of value. */
+SymbolicExpression dereference(SymbolicExpression value, ReferenceExpression reference);
+
+/** Returns the identity (or "trivial") reference I.  This is the reference characterized by the
+ * property that dereference(I,v) returns v for any symbolic expression v. */
+ReferenceExpression identityReference();
+
+/** Given a reference to an array and an index (integer), returns a reference to the element of the array
+ * at that index */
+ArrayElementReference arrayElementReference(ReferenceExpression arrayReference, NumericExpression index);
+
+/** Given a reference to a tuple, and a field index, returns a reference to that component of the tuple */
+TupleComponentReference tupleComponentReference(ReferenceExpression tupleReference, IntObject fieldIndex);
+
+/** Given a reference to a union (expression of union type) and an index of  a member type of that union, returns
+ * a reference to the underlying element */
+UnionMemberReference unionElementReference(ReferenceExpression unionReference, IntObject memberIndex);
+
+OffsetReference offsetReference(ReferenceExpression reference, NumericExpression offset);
+
+/** Given a symbolic expression value, a reference to a point within that value, and a subValue, returns
+ * the symbolic expression obtained by replacing the referenced part of value with subValue. */
+SymbolicExpression assign(SymbolicExpression value, ReferenceExpression reference, SymbolicExpression subValue);
+}}}