GriffinRelationImpl.mesa
Copyright © 1985 by Xerox Corporation. All rights reserved.
Edited by: Maureen Stone, September 19, 1985 12:23:31 pm PDT
Last Edited by: Ken Pier, November 13, 1985 4:49:38 pm PST
DIRECTORY
GriffinRelation USING [AllPairProc, notFound, Pair, Relation, RelationHead],
UnsafeStorage USING [GetSystemUZone, NewUObject];
GriffinRelationImpl:
PROGRAM
IMPORTS UnsafeStorage EXPORTS GriffinRelation = BEGIN
UCZone: UNCOUNTED ZONE ← UnsafeStorage.GetSystemUZone[];
Allocate:
PROC [nwords:
CARDINAL]
RETURNS [
LONG
POINTER] = {
RETURN[UnsafeStorage.NewUObject[nwords,UCZone]];
};
Free: PROC [ptr: LONG POINTER] = { IF ptr#NIL THEN UCZone.FREE[@ptr]; };
CreateRelation:
PUBLIC
PROC
RETURNS [relation: GriffinRelation.Relation] = {
relation ← Allocate[SIZE[GriffinRelation.RelationHead]];
relation.first ← NIL;
};
AddPair:
PUBLIC
PROC [relation: GriffinRelation.Relation, left, right:
CARDINAL] = {
pair: LONG POINTER TO GriffinRelation.Pair ← Allocate[SIZE[GriffinRelation.Pair]];
pair.left ← left; pair.right ← right;
pair.link ← relation.first;
relation.first ← pair;
};
Left:
PUBLIC
PROC [relation: GriffinRelation.Relation, right:
CARDINAL]
RETURNS [left:
CARDINAL] = {
IsRight:
PROC [leftPart, rightPart:
CARDINAL] = {
IF right=rightPart THEN left←leftPart;
};
left←GriffinRelation.notFound;
ForAllPairs[relation, IsRight];
};
Right:
PUBLIC
PROC [relation: GriffinRelation.Relation, left:
CARDINAL]
RETURNS [right:
CARDINAL] = {
IsLeft:
PROC [leftPart, rightPart:
CARDINAL] = {
IF left=leftPart THEN right←rightPart;
};
right←GriffinRelation.notFound;
ForAllPairs[relation, IsLeft];
};
ForAllPairs:
PUBLIC
PROC [relation: GriffinRelation.Relation, Proc: GriffinRelation.AllPairProc] = {
pair: LONG POINTER TO GriffinRelation.Pair ← NIL;
FOR pair ← relation.first, pair.link UNTIL pair=NIL
DO Proc[pair.left, pair.right] ENDLOOP;
};
DestroyRelation:
PUBLIC
PROC [relation: GriffinRelation.Relation] = {
pair, next: LONG POINTER TO GriffinRelation.Pair ← NIL;
FOR pair ← relation.first, next UNTIL pair=NIL
DO
next ← pair.link;
Free[pair];
ENDLOOP;
Free[relation];
};