
<<SimpleClientImpl.mesa>>
<<Last Edited by: Arnon, January 25, 1985 12:29:01 pm PST>>
<<>>
DIRECTORY
Rope,
ClientStateInfo;

SimpleClientImpl: CEDAR PROGRAM
IMPORTS Rope
EXPORTS ClientStateInfo =

BEGIN OPEN ClientStateInfo;

PrivateState: TYPE = REF InclusionRelation;
InclusionRelation: TYPE = { inside };  -- our model is that retained areas have state "inside", and unretained areas have state NIL

defaultState: PUBLIC State _ NEW[InclusionRelation _ inside ];

BooleanFunction: TYPE = { Union, Difference };

stateCombiner: PUBLIC StateCombiner = {
RETURN[ NIL ]; -- Difference function (default)
};

    StateEqual: PUBLIC PROC [state1, state2: State] RETURNS [BOOL] ~ {
    s1: PrivateState _ NARROW[state1];
    s2: PrivateState _ NARROW[state2];
        IF state1=NIL OR state2=NIL THEN RETURN[state1=NIL AND state2 = NIL];
    RETURN[s1^ = s2^];
        };

    RopeFromState: PUBLIC PROC [state: State] RETURNS [Rope.ROPE] ~ {
        s: PrivateState _ NARROW[state];
        IF state=NIL THEN RETURN["NIL"];
        IF s^ = inside THEN RETURN["inside"] ELSE ERROR;
        };

    StateFromRope: PUBLIC PROC [in: Rope.ROPE] RETURNS [s: State] ~ {
        IF Rope.Equal[in, "NIL"] THEN RETURN[NIL] ELSE IF Rope.Equal[in, "inside"] THEN RETURN[NEW[InclusionRelation _ inside]] ELSE  ERROR;

        };

END.