
<<RatIntervalsImpl.mesa>>
<<Last Edited by: Arnon, July 19, 1985 2:54:46 pm PDT>>
<<>>
DIRECTORY
Rope,
    IO,
BigRats,
AlgebraClasses,
RatIntervals;

RatIntervalsImpl: CEDAR PROGRAM
IMPORTS Rope, IO, BigRats
EXPORTS RatIntervals

= BEGIN OPEN BR: BigRats, RatIntervals;

<<>>
ReadRatInterval: PUBLIC PROC [in: IO.STREAM] RETURNS [out: RatInterval] ~ {
puncChar: CHAR;
leftEndPoint, rightEndPoint: BR.BigRat;
[]_ in.SkipWhitespace[];
puncChar _ in.GetChar[ ];
IF puncChar # '( THEN ERROR;
leftEndPoint _ NARROW[ BR.BigRats.class.read[in, BR.BigRats] ];
[]_ in.SkipWhitespace[];
puncChar _ in.GetChar[ ];
IF puncChar # ', THEN ERROR;
rightEndPoint _ NARROW[ BR.BigRats.class.read[in, BR.BigRats] ];
[]_ in.SkipWhitespace[];
puncChar _ in.GetChar[ ];
IF puncChar # ') THEN ERROR;
RETURN[NEW[RatIntervalRec _ [leftEndPoint, rightEndPoint] ] ];
};

RatIntervalFromRope: PUBLIC PROC [in: Rope.ROPE] RETURNS [out: RatInterval] = {
    stream: IO.STREAM _ IO.RIS[in];
    out _ ReadRatInterval[stream];
    };

RatIntervalToRope: PUBLIC PROC [in: RatInterval, showDenomOne: BOOL _ FALSE] RETURNS [out: Rope.ROPE] ~ {
out _ "( "; 
    out _ Rope.Cat[out, BR.BigRats.class.toRope[in.leftEndPoint], " , "];
    out _ Rope.Cat[out, BR.BigRats.class.toRope[in.rightEndPoint], " )"];
    };

WriteRatInterval: PUBLIC PROC [in: RatInterval, out: IO.STREAM, showDenomOne: BOOL _ FALSE] ~ {
ratIntRope: Rope.ROPE _ RatIntervalToRope[in, showDenomOne];
out.PutF["%g\n", IO.rope[ratIntRope] ];
};


END.