TSGlue.mesa
Definitions pertaining to glue
Michael Plass, November 2, 1982 10:03 am
TSGlue: CEDAR DEFINITIONS IMPORTS TSTypes =
BEGIN OPEN TSTypes;
Your basic glue
Glue: TYPE = RECORD [space: Dimn, stretch: Dimn, shrink: Dimn];
zeroGlue: Glue = [zeroDimn, zeroDimn, zeroDimn];
Constants for making infinite glue
fil: Dimn = [texPts: 1.0E+5];
fill: Dimn = [texPts: 1.0E+10];
filll: Dimn = [texPts: 1.0E+15];
Glue sums have a special representation to allow cancellation of infinite glue items without undue loss of precision.
Flex: TYPE = ARRAY [0..3] OF Dimn;
zeroFlex: Flex = [zeroDimn, zeroDimn, zeroDimn, zeroDimn];
GlueSum: TYPE = RECORD [space: Dimn, stretch: Flex, shrink: Flex];
zeroGlueSum: GlueSum = [zeroDimn, zeroFlex, zeroFlex];
AddGlue:
PROCEDURE [t: GlueSum, g: Glue]
RETURNS [s: GlueSum] =
INLINE {
s ← t;
s.space.texPts ← s.space.texPts + g.space.texPts;
SELECT
ABS[g.stretch.texPts]
FROM
< fil.texPts => s.stretch[0].texPts ← s.stretch[0].texPts + g.stretch.texPts;
< fill.texPts => s.stretch[1].texPts ← s.stretch[1].texPts + g.stretch.texPts;
< filll.texPts => s.stretch[2].texPts ← s.stretch[2].texPts + g.stretch.texPts;
ENDCASE => s.stretch[3].texPts ← s.stretch[3].texPts + g.stretch.texPts;
SELECT
ABS[g.shrink.texPts]
FROM
< fil.texPts => s.shrink[0].texPts ← s.shrink[0].texPts + g.shrink.texPts;
< fill.texPts => s.shrink[1].texPts ← s.shrink[1].texPts + g.shrink.texPts;
< filll.texPts => s.shrink[2].texPts ← s.shrink[2].texPts + g.shrink.texPts;
ENDCASE => s.shrink[3].texPts ← s.shrink[3].texPts + g.shrink.texPts;
};
GlueFromSum:
PROCEDURE [s: GlueSum]
RETURNS [Glue] =
INLINE {
RETURN[[space: s.space,
stretch: [s.stretch[0].texPts + s.stretch[1].texPts + s.stretch[2].texPts + s.stretch[3].texPts],
shrink: [s.shrink[0].texPts + s.shrink[1].texPts + s.shrink[2].texPts + s.shrink[3].texPts]]]
};
GlueSet: TYPE = RECORD[value: REAL];
zeroGlueSet: GlueSet = [value: 0];
overfullGlueSet: GlueSet = [value: -1.0625];
SetGlue: PROCEDURE [desired: Dimn, g: Glue] RETURNS [GlueSet];
GlueBadness: PROCEDURE [GlueSet] RETURNS [Badness];
FixGlue:
PROCEDURE [glue: Glue, set: GlueSet]
RETURNS [d: Dimn] =
INLINE {
d ←
IF set.value<0
THEN AddDimn[glue.space, RealDimn[set.value, glue.shrink]]
ELSE AddDimn[glue.space, RealDimn[set.value, glue.stretch]]
};
END.
Michael Plass, November 2, 1982 10:03 am. CEDARized.