
    <<HashPairCollectionsPublicImpl.Mesa>>
        <<Last tweaked by Mike Spreitzer on August 28, 1987 10:45:05 am PDT>>

    DIRECTORY HashPairCollectionsPrivate, HashTables, Collections, PairCollections;

    HashPairCollectionsPublicImpl: CEDAR PROGRAM
        IMPORTS HashPairCollectionsPrivate, HashTables, Collections, PairCollections
        EXPORTS PairCollections
        =

    BEGIN OPEN HT:HashTables, Colls:Collections, Collections, PairCollections, HashPairCollectionsPrivate;

    CreateHashReln: PUBLIC PROC [spaces: SpacePair _ [NIL, NIL], functional: BoolPair _ [FALSE, FALSE], mappable: BoolPair _ [TRUE, 
    TRUE]] RETURNS [VarPairColl] ~ {
        ability: Abilities;
        FOR dir: Direction IN Direction DO
            IF spaces[Source[dir]]=NIL THEN spaces[Source[dir]] _ Colls.refs;
            ability[dir] _ IF functional[dir] THEN map ELSE IF mappable[dir] THEN image ELSE none;
            ENDLOOP;
        {bestDir: Direction ~ IF ability[rightToLeft] > ability[leftToRight] THEN rightToLeft ELSE leftToRight;
        hr: HashRelation ~ NEW [HashRelationPrivate _ [
            spaces: spaces,
            ability: ability,
            bestDir: bestDir,
            bestAbility: ability[bestDir],
            tables: [HT.Create[spaces[left]], HT.Create[spaces[right]]]
            ]];
        RETURN [AsVar[[FetchClass[hr.ability, variable], hr]]];
        }};

    CreateHashCopy: PUBLIC PROC [pc: PairColl, spaces: SpacePair _ [NIL, NIL], mappable: BoolPair _ [FALSE, FALSE]] RETURNS [copy: 
    HashFn] ~ {
        FOR side: Side IN Side DO
            IF spaces[side]=NIL THEN spaces[side] _ pc.Spaces[][side];
            IF pc.QualityOf[$Image, LIST[IF side=left THEN $leftToRight ELSE $rightToLeft]] >= goodDefault THEN mappable[From[side]] _ TRUE;
            ENDLOOP;
        copy _ CreateHashReln[spaces, pc.Functional, mappable];
        [] _ copy.AddColl[pc];
        };

    END.