Copyright (C) 1994, Digital Equipment Corp.
MODULE Rect;
IMPORT Word, Point, Axis, Interval;
PROCEDURE FromEdges (w, e, n, s: INTEGER): T RAISES {} =
VAR r: T;
BEGIN
IF (w >= e) OR (n >= s) THEN RETURN Empty; END;
r.west := w;
r.east := e;
r.north := n;
r.south := s;
RETURN r;
END FromEdges;
PROCEDURE FromAbsEdges (w, e, n, s: INTEGER): T RAISES {} =
VAR r: T;
BEGIN
IF (w = e) OR (n = s) THEN RETURN Empty; END;
IF (w < e) THEN
r.west := w;
r.east := e;
ELSE
r.west := e;
r.east := w;
END;
IF (n < s) THEN
r.north := n;
r.south := s;
ELSE
r.north := s;
r.south := n;
END;
RETURN r;
END FromAbsEdges;
PROCEDURE FromPoint (READONLY p: Point.T): T RAISES {} =
BEGIN
RETURN FromEdges (p.h, p.h + 1, p.v, p.v + 1);
END FromPoint;
PROCEDURE FromCorners (READONLY p, q: Point.T): T RAISES {} =
BEGIN
RETURN FromAbsEdges (p.h, q.h, p.v, q.v);
END FromCorners;
PROCEDURE FromCorner (READONLY p: Point.T; hor, ver: CARDINAL): T RAISES {} =
VAR r: T;
BEGIN
IF (hor = 0) OR (ver = 0) THEN RETURN Empty; END;
r.west := p.h;
r.east := p.h + hor;
r.north := p.v;
r.south := p.v + ver;
RETURN r;
END FromCorner;
PROCEDURE FromSize (hor, ver: CARDINAL): T RAISES {} =
VAR r: T;
BEGIN
IF (hor = 0) OR (ver = 0) THEN RETURN Empty; END;
r.west := 0;
r.east := hor;
r.north := 0;
r.south := ver;
RETURN r;
END FromSize;
PROCEDURE Center (READONLY r: T; READONLY p: Point.T): T RAISES {} =
VAR res: T; h, v: INTEGER;
BEGIN
IF r.west >= r.east THEN RETURN Empty END;
h := p.h - (r.west + r.east) DIV 2;
v := p.v - (r.north + r.south) DIV 2;
res.west := r.west + h;
res.east := r.east + h;
res.north := r.north + v;
res.south := r.south + v;
RETURN res
END Center;
PROCEDURE FromIntervals (READONLY hor, ver: Interval.T): T RAISES {} =
VAR r: T;
BEGIN
IF (hor.lo = hor.hi) OR (ver.lo = ver.hi) THEN RETURN Empty; END;
r.west := hor.lo;
r.east := hor.hi;
r.north := ver.lo;
r.south := ver.hi;
RETURN r;
END FromIntervals;
PROCEDURE FromAxes (axis: Axis.T; READONLY n, m: Interval.T): T RAISES {} =
VAR r: T;
BEGIN
IF (n.lo = n.hi) OR (m.lo = m.hi) THEN RETURN Empty END;
IF (axis = Axis.T.Hor) THEN
r.west := n.lo;
r.east := n.hi;
r.north := m.lo;
r.south := m.hi;
ELSE
r.west := m.lo;
r.east := m.hi;
r.north := n.lo;
r.south := n.hi;
END;
RETURN r
END FromAxes;
PROCEDURE NorthWest (READONLY r: T): Point.T RAISES {} =
VAR p: Point.T;
BEGIN
p.h := r.west;
p.v := r.north;
RETURN p;
END NorthWest;
PROCEDURE NorthEast (READONLY r: T): Point.T RAISES {} =
VAR p: Point.T;
BEGIN
p.h := r.east;
p.v := r.north;
RETURN p;
END NorthEast;
PROCEDURE SouthWest (READONLY r: T): Point.T RAISES {} =
VAR p: Point.T;
BEGIN
p.h := r.west;
p.v := r.south;
RETURN p;
END SouthWest;
PROCEDURE SouthEast (READONLY r: T): Point.T RAISES {} =
VAR p: Point.T;
BEGIN
p.h := r.east;
p.v := r.south;
RETURN p;
END SouthEast;
PROCEDURE GetVertex (v: Vertex; READONLY r: T): Point.T RAISES {} =
BEGIN
IF (r.west >= r.east)(* OR (r.north>=r.south) *) THEN
RETURN Point.Origin;
END;
CASE v OF
| Vertex.NW => RETURN NorthWest (r);
| Vertex.NE => RETURN NorthEast (r);
| Vertex.SW => RETURN SouthWest (r);
| Vertex.SE => RETURN SouthEast (r);
END;
END GetVertex;
PROCEDURE HorSize (READONLY r: T): CARDINAL RAISES {} =
BEGIN
RETURN r.east - r.west;
END HorSize;
PROCEDURE VerSize (READONLY r: T): CARDINAL RAISES {} =
BEGIN
RETURN r.south - r.north
END VerSize;
PROCEDURE Size (a: Axis.T; READONLY r: T): CARDINAL RAISES {} =
BEGIN
CASE a OF
| Axis.T.Hor => RETURN HorSize (r);
| Axis.T.Ver => RETURN VerSize (r);
END;
END Size;
PROCEDURE DiagSizeSquare (READONLY r: T): CARDINAL RAISES {} =
VAR hor, ver: INTEGER;
BEGIN
hor := HorSize (r);
ver := VerSize (r);
RETURN hor * hor + ver * ver;
END DiagSizeSquare;
PROCEDURE Middle (READONLY r: T): Point.T RAISES {} =
BEGIN
RETURN Point.T{(r.west+r.east) DIV 2, (r.north+r.south) DIV 2}
END Middle;
PROCEDURE PickEdge (READONLY r: T; READONLY p: Point.T): Edge RAISES {} =
VAR mid, se, q: Point.T; a, b: INTEGER;
BEGIN
mid := Middle (r);
se := Point.Sub (SouthEast (r), mid);
q := Point.Sub (p, mid);
a := se.v * q.h;
b := se.h * q.v;
IF a >= b THEN
IF -a >= b THEN RETURN Edge.N ELSE RETURN Edge.E END;
ELSE
IF -a >= b THEN RETURN Edge.W ELSE RETURN Edge.S END;
END;
END PickEdge;
PROCEDURE PickVertex (READONLY r: T; READONLY p: Point.T): Vertex RAISES {} =
VAR q: Point.T;
BEGIN
q := Point.Sub (p, Middle (r));
IF q.h > 0 THEN
IF q.v > 0 THEN RETURN Vertex.SE ELSE RETURN Vertex.NE END;
ELSE
IF q.v > 0 THEN RETURN Vertex.SW ELSE RETURN Vertex.NW END;
END;
END PickVertex;
PROCEDURE Project (READONLY r: T; READONLY p: Point.T): Point.T RAISES {} =
VAR res: Point.T;
BEGIN
<* ASSERT r.east > r.west *>
res.h := MAX (MIN (p.h, r.east - 1), r.west);
res.v := MAX (MIN (p.v, r.south - 1), r.north);
RETURN res
END Project;
PROCEDURE Add (READONLY r: T; READONLY p: Point.T): T RAISES {} =
VAR s: T;
BEGIN
IF r.west >= r.east THEN RETURN Empty END;
s.west := r.west + p.h;
s.east := r.east + p.h;
s.north := r.north + p.v;
s.south := r.south + p.v;
RETURN s;
END Add;
PROCEDURE Sub (READONLY r: T; READONLY p: Point.T): T RAISES {} =
VAR s: T;
BEGIN
IF r.west >= r.east THEN RETURN Empty END;
s.west := r.west - p.h;
s.east := r.east - p.h;
s.north := r.north - p.v;
s.south := r.south - p.v;
RETURN s;
END Sub;
PROCEDURE Move (READONLY r: T; READONLY p: Point.T): T RAISES {} =
VAR s: T;
BEGIN
IF r.west >= r.east THEN RETURN Empty END;
s.west := r.west + p.h;
s.east := r.east + p.h;
s.north := r.north + p.v;
s.south := r.south + p.v;
RETURN s;
END Move;
PROCEDURE MoveH (READONLY r: T; h: INTEGER): T RAISES {} =
VAR s: T;
BEGIN
IF r.west >= r.east THEN RETURN Empty END;
s.west := r.west + h;
s.east := r.east + h;
s.north := r.north;
s.south := r.south;
RETURN s;
END MoveH;
PROCEDURE MoveV (READONLY r: T; v: INTEGER): T RAISES {} =
VAR s: T;
BEGIN
IF r.west >= r.east THEN RETURN Empty END;
s.west := r.west;
s.east := r.east;
s.north := r.north + v;
s.south := r.south + v;
RETURN s;
END MoveV;
PROCEDURE MoveHV (READONLY r: T; h: INTEGER; v: INTEGER): T RAISES {} =
VAR s: T;
BEGIN
IF r.west >= r.east THEN RETURN Empty END;
s.west := r.west + h;
s.east := r.east + h;
s.north := r.north + v;
s.south := r.south + v;
RETURN s;
END MoveHV;
PROCEDURE Scale (READONLY r: T; num, den: INTEGER): T RAISES {} =
VAR s: T;
BEGIN
IF r.west >= r.east THEN RETURN Empty END;
s.north := (r.north * num) DIV den;
s.south := (r.south * num) DIV den;
IF s.north >= s.south THEN
RETURN Empty
ELSE
s.west := (r.west * num) DIV den;
s.east := (r.east * num) DIV den;
IF s.west >= s.east THEN RETURN Empty END;
RETURN s
END;
END Scale;
PROCEDURE Inset (READONLY r: T; n: INTEGER): T RAISES {} =
VAR s: T;
BEGIN
IF (r.west >= r.east) OR (r.north >= r.south) THEN RETURN Empty END;
s.west := r.west + n;
s.east := r.east - n;
s.north := r.north + n;
s.south := r.south - n;
IF (s.west >= s.east) OR (s.north >= s.south) THEN RETURN Empty; END;
RETURN s;
END Inset;
PROCEDURE Change (READONLY r: T; dw, de, dn, ds: INTEGER): T RAISES {} =
VAR s: T;
BEGIN
IF (r.west >= r.east) OR (r.north >= r.south) THEN RETURN Empty; END;
s.west := r.west + dw;
s.east := r.east + de;
s.north := r.north + dn;
s.south := r.south + ds;
IF (s.west >= s.east) OR (s.north >= s.south) THEN RETURN Empty; END;
RETURN s;
END Change;
PROCEDURE MoveEdge (READONLY r: T; e: Edge; dn: INTEGER): T RAISES {} =
VAR s: T;
BEGIN
IF r.west >= r.east THEN RETURN Empty END;
s := r;
CASE e OF
| Edge.W => s.west := r.west + dn;
| Edge.E => s.east := r.east + dn;
| Edge.N => s.north := r.north + dn;
| Edge.S => s.south := r.south + dn;
END;
IF (s.west >= s.east) OR (s.north >= s.south) THEN RETURN Empty; END;
RETURN s;
END MoveEdge;
PROCEDURE MoveVertex (READONLY r: T; v: Vertex; READONLY dp: Point.T): T
RAISES {} =
VAR s: T;
BEGIN
IF r.west >= r.east THEN RETURN Empty END;
s := r;
CASE v OF
| Vertex.NW => s.west := r.west + dp.h; s.north := r.north + dp.v;
| Vertex.NE => s.east := r.east + dp.h; s.north := r.north + dp.v;
| Vertex.SW => s.west := r.west + dp.h; s.south := r.south + dp.v;
| Vertex.SE => s.east := r.east + dp.h; s.south := r.south + dp.v;
END;
IF (s.west >= s.east) OR (s.north >= s.south) THEN RETURN Empty; END;
RETURN s;
END MoveVertex;
PROCEDURE Stretch (READONLY r: T; axis: Axis.T; lo, hi: INTEGER): T RAISES {} =
VAR res: T;
BEGIN
IF (r.west >= r.east) OR lo >= hi THEN RETURN Empty; END;
IF axis = Axis.T.Hor THEN
res.north := r.north;
res.south := r.south;
res.west := lo;
res.east := hi
ELSE
res.north := lo;
res.south := hi;
res.west := r.west;
res.east := r.east
END;
RETURN res
END Stretch;
PROCEDURE Join (READONLY r, s: T): T RAISES {} =
VAR t: T;
BEGIN
IF (r.west >= r.east)(* OR (r.north>=r.south) *) THEN RETURN s; END;
IF (s.west >= s.east)(* OR (s.north>=s.south) *) THEN RETURN r; END;
t.west := MIN (r.west, s.west);
t.east := MAX (r.east, s.east);
t.north := MIN (r.north, s.north);
t.south := MAX (r.south, s.south);
RETURN t;
END Join;
PROCEDURE Meet (READONLY r, s: T): T RAISES {} =
VAR t: T;
BEGIN
t.west := MAX (r.west, s.west);
t.east := MIN (r.east, s.east);
IF t.west >= t.east THEN RETURN Empty END;
t.north := MAX (r.north, s.north);
t.south := MIN (r.south, s.south);
IF t.north >= t.south THEN RETURN Empty; END;
RETURN t;
END Meet;
PROCEDURE Extend (READONLY r: T; READONLY p: Point.T): T RAISES {} =
BEGIN
RETURN Join (r, FromPoint (p));
END Extend;
PROCEDURE Chop
(hv: Axis.T; READONLY r: T; n: INTEGER; VAR s, t: T) RAISES {} =
BEGIN
IF (hv = Axis.T.Hor) THEN
IF n <= r.west THEN
s := Empty;
t := r
ELSIF n >= r.east THEN
s := r;
t := Empty
ELSE
s.north := r.north;
s.south := r.south;
t.north := r.north;
t.south := r.south;
s.west := r.west;
s.east := n;
t.west := n;
t.east := r.east
END
ELSE
IF n <= r.north THEN
s := Empty;
t := r
ELSIF n >= r.south THEN
s := r;
t := Empty
ELSE
s.west := r.west;
s.east := r.east;
t.west := r.west;
t.east := r.east;
s.north := r.north;
s.south := n;
t.north := n;
t.south := r.south
END
END
END Chop;
This is what it really means:
PROCEDURE Factor(VAR IN r, by: T; VAR f: Partition; dh, dv: INTEGER)
RAISES {}; VAR northIndex, westIndex: INTEGER; mid, temp: T; BEGIN IF dh >
0 THEN westIndex := 3 ELSE westIndex := 1 END; IF dv > 0 THEN northIndex
:= 4 ELSE northIndex := 0 END; Chop(Axis.Ver, r, by.north, f[northIndex],
temp); Chop(Axis.Ver, temp, by.south, mid, f[4 - northIndex]);
Chop(Axis.Hor, mid, by.west, f[westIndex], temp); Chop(Axis.Hor, temp,
by.east, f[2], f[4 - westIndex]); END Factor;
PROCEDURE Factor (READONLY r, by: T; VAR f: Partition; dh, dv: INTEGER)
RAISES {} =
VAR ix, rw, re, rn, rs, bw, be, bn, bs: INTEGER; temp: T;
BEGIN
bw := by.west;
be := by.east;
bn := by.north;
bs := by.south;
rw := r.west;
re := r.east;
rn := r.north;
rs := r.south;
IF bw >= be OR rw >= re THEN
f[0] := r;
FOR z := 1 TO 4 DO f[z] := Empty END;
RETURN
END;
IF dv > 0 THEN ix := 4 ELSE ix := 0 END;
IF rn < bn THEN
WITH z = f[ix] DO z.west := rw; z.east := re; z.north := rn END;
IF bn < rs THEN
f[ix].south := bn;
WITH z = temp DO z.west := rw; z.east := re; z.north := bn END;
IF bs < rs THEN
temp.south := bs;
WITH z = f[4 - ix] DO
z.west := rw;
z.east := re;
z.north := bs;
z.south := rs
END
ELSE
temp.south := rs;
f[4 - ix] := Empty
END
ELSE
f[ix].south := rs;
temp := Empty;
f[4 - ix] := Empty
END
ELSE
f[ix] := Empty;
IF rn < bs THEN
WITH z = temp DO z.west := rw; z.east := re; z.north := rn END;
IF bs < rs THEN
temp.south := bs;
WITH z = f[4 - ix] DO
z.west := rw;
z.east := re;
z.north := bs;
z.south := rs
END
ELSE
temp.south := rs;
f[4 - ix] := Empty
END
ELSE
temp := Empty;
f[4 - ix] := r
END
END;
rw := temp.west;
re := temp.east;
rn := temp.north;
rs := temp.south;
IF rw >= re THEN
FOR z := 1 TO 3 DO f[z] := Empty END;
RETURN
END;
IF dh > 0 THEN ix := 3 ELSE ix := 1 END;
IF rw < bw THEN
WITH z = f[ix] DO z.north := rn; z.south := rs; z.west := rw END;
IF bw < re THEN
f[ix].east := bw;
WITH z = f[2] DO z.north := rn; z.south := rs; z.west := bw END;
IF be < re THEN
f[2].east := be;
WITH z = f[4 - ix] DO
z.north := rn;
z.south := rs;
z.west := be;
z.east := re
END
ELSE
f[2].east := re;
f[4 - ix] := Empty
END
ELSE
f[ix].east := re;
f[2] := Empty;
f[4 - ix] := Empty
END
ELSE
f[ix] := Empty;
IF rw < be THEN
WITH z = f[2] DO z.north := rn; z.south := rs; z.west := rw END;
IF be < re THEN
f[2].east := be;
WITH z = f[4 - ix] DO
z.north := rn;
z.south := rs;
z.west := be;
z.east := re
END
ELSE
f[2].east := re;
f[4 - ix] := Empty
END
ELSE
f[2] := Empty;
f[4 - ix] := temp
END
END
END Factor;
PROCEDURE Mod (READONLY p: Point.T; READONLY r: T): Point.T RAISES {} =
VAR q: Point.T; hor, ver: Interval.T;
BEGIN
<* ASSERT r.west < r.east *>
hor.lo := r.west;
hor.hi := r.east;
ver.lo := r.north;
ver.hi := r.south;
q.h := Interval.Mod (p.h, hor);
q.v := Interval.Mod (p.v, ver);
RETURN q
END Mod;
PROCEDURE Equal (READONLY r, s: T): BOOLEAN RAISES {} =
BEGIN
RETURN r = s
END Equal;
PROCEDURE IsEmpty (READONLY r: T): BOOLEAN RAISES {} =
BEGIN RETURN (r.west >= r.east) END IsEmpty;
PROCEDURE Member (READONLY p: Point.T; READONLY r: T): BOOLEAN RAISES {} =
BEGIN
RETURN (r.west <= p.h) AND (p.h < r.east) AND (r.north <= p.v)
AND (p.v < r.south);
END Member;
PROCEDURE Overlap (READONLY r, s: T): BOOLEAN RAISES {} =
BEGIN
RETURN (MAX (r.west, s.west) < MIN (r.east, s.east))
AND (MAX (r.north, s.north) < MIN (r.south, s.south));
END Overlap;
PROCEDURE Subset (READONLY r, s: T): BOOLEAN RAISES {} =
BEGIN
RETURN (r.west >= r.east)
OR ((r.west >= s.west) AND (r.east <= s.east) AND (r.north >= s.north)
AND (r.south <= s.south));
END Subset;
PROCEDURE Congruent(READONLY r, s: T): BOOLEAN =
BEGIN
RETURN r.east - r.west = s.east - s.west
AND r.south - r.north = s.south - s.north
END Congruent;
PROCEDURE Transpose(READONLY r: T; ax := Axis.T.Ver): T =
BEGIN
IF ax = Axis.T.Hor THEN
RETURN r
ELSE
RETURN T{r.north,r.south,r.west,r.east}
END
END Transpose;
PROCEDURE GlobToLoc (READONLY r: T; READONLY p: Point.T): Point.T RAISES {} =
VAR q: Point.T;
BEGIN
q.h := p.h - r.west;
q.v := p.v - r.north;
RETURN q;
END GlobToLoc;
PROCEDURE LocToGlob (READONLY r: T; READONLY p: Point.T): Point.T RAISES {} =
VAR q: Point.T;
BEGIN
q.h := p.h + r.west;
q.v := p.v + r.north;
RETURN q;
END LocToGlob;
PROCEDURE Compare (READONLY a, b: T): INTEGER =
BEGIN
IF (a.west < b.west) THEN RETURN -1 END;
IF (a.west > b.west) THEN RETURN +1 END;
IF (a.east < b.east) THEN RETURN -1 END;
IF (a.east > b.east) THEN RETURN +1 END;
IF (a.north < b.north) THEN RETURN -1 END;
IF (a.north > b.north) THEN RETURN +1 END;
IF (a.south < b.south) THEN RETURN -1 END;
IF (a.south > b.south) THEN RETURN +1 END;
RETURN 0;
END Compare;
PROCEDURE Hash (READONLY a: T): Word.T =
BEGIN
RETURN Word.Xor (Word.Xor (a.west, a.east), Word.Xor (a.north, a.south));
END Hash;
BEGIN
END Rect.