This module maintains the virtual screen structures. The following
invariants are maintained:
Up(start.at, 0) = start.at, with secondary results start.min, start.max and start.turned. (start.max may be conservative.) If vt^.length > 0, then start.at < vt^.length. Changing the buffer keeps start.at valid.
If line[i].virtualLine.valid, then ComputeLine(line[i].virtualLine.from) = line[i].virtualLine.to, with secondary results line[i].virtualLine.max, line[i].virtualLine.width, and line[i].virtualLine.turned.
dirty is true if any line[i].virtualLine.valid is false, or if the information is otherwise obsolete. Otherwise, then the line[i] are all in order and contiguous, starting at start.at.
If only the start of the buffer is dirty, then bodyDirty will be FALSE and dirty will be TRUE.
line[0] through line[nLines-1] are defined, as is
line[nLines].virtualLine.from. When dirty is false, lines is the number
of non-empty elements (an element may be empty if it is at the end of the
buffer, or if the next character will not fit within the lineWidth).
MODULE; IMPORT Rd, Thread; IMPORT VTDef, VTRd, VTReal, VTBase; TYPE LineNo = VTDef.LineNo; PROCEDURE VTVirtual Change (vt: T; begin, oEnd, nEnd: I) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted} = (* Change notes a change made in the mtext. *) VAR view: View; i : LineNo; d : INTEGER; at : I; BEGIN IF (oEnd = begin) AND (nEnd = begin) THEN RETURN; END; d := nEnd - oEnd; vt.length := vt.length + d; view := vt.views; WHILE view # NIL DO WITH z_126 = view^ DO (* check lines *) at := z_126.virtual.line [0].virtualLine.from; FOR z_127 := 0 TO z_126.nLines - 1 DO i := z_127; WITH z_128 = z_126.virtual.line [i] DO IF z_128.virtualLine.valid THEN IF oEnd <= z_128.virtualLine.from THEN z_128.virtualLine.from := z_128.virtualLine.from + d; z_128.virtualLine.to := z_128.virtualLine.to + d; z_128.virtualLine.max := z_128.virtualLine.max + d; ELSIF begin < z_128.virtualLine.max THEN z_128.virtualLine.valid := FALSE; IF begin < z_128.virtualLine.from THEN z_128.virtualLine.from := begin; END; IF oEnd <= z_128.virtualLine.to THEN z_128.virtualLine.to := z_128.virtualLine.to + d; ELSIF begin < z_128.virtualLine.to THEN z_128.virtualLine.to := nEnd; END; IF oEnd <= z_128.virtualLine.max THEN z_128.virtualLine.max := z_128.virtualLine.max + d; ELSIF begin < z_128.virtualLine.max THEN z_128.virtualLine.max := nEnd; END; Dirtied (view, i, 1); END; IF z_128.virtualLine.from # at THEN Dirtied (view, i, 0); END; at := z_128.virtualLine.to; END; END; END; z_126.virtual.line [z_126.nLines].virtualLine.from := at; (* check start *) IF oEnd <= z_126.virtual.start.min THEN z_126.virtual.start.min := z_126.virtual.start.min + d; z_126.virtual.start.max := z_126.virtual.start.max + d; z_126.virtual.start.at := z_126.virtual.start.at + d; ELSIF begin < z_126.virtual.start.max THEN IF oEnd <= z_126.virtual.start.at THEN SetStart (view, z_126.virtual.start.at + d); ELSIF begin < z_126.virtual.start.at THEN SetStart (view, begin); ELSE SetStart (view, z_126.virtual.start.at); END; END; IF (z_126.virtual.start.at = z_126.vt.length) AND (z_126.virtual.start.at > 0) THEN SetStart (view, z_126.virtual.start.at - 1); END; IF z_126.virtual.start.at # z_126.virtual.line [0].virtualLine.from THEN Dirtied (view, 0, 0, FALSE); END; (* next view *) view := z_126.next; END; END; VTReal.Change (vt, begin, oEnd, nEnd); END Change; PROCEDURESetStart (view : View; from : I; n : CARDINAL := 0; force: BOOLEAN := FALSE) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted} = VAR at: I; BEGIN at := view.virtual.start.at; IF force AND n = 0 THEN view.virtual.start.at := from; view.virtual.start.min := from; view.virtual.start.max := from; IF from = 0 THEN view.virtual.start.turned := FALSE; ELSE VTRd.InitReaderIx(view.vt, from - 1); view.virtual.start.turned := Rd.GetChar(view.vt.rd) # '\n'; END; ELSE VTBase.Up(view, view.lineWidth, from, n, view.virtual.start); END; <* ASSERT view.virtual.start.min <= view.virtual.start.at AND view.virtual.start.at <= view.virtual.start.max *> IF view.virtual.start.at # at THEN Dirtied(view, 0, 0, FALSE); END; IF view.virtual.start.at > 0 AND view.virtual.start.at = view.vt.length AND NOT force THEN VTBase.Up(view, view.lineWidth, view.virtual.start.at - 1, 0, view.virtual.start); <* ASSERT view.virtual.start.min <= view.virtual.start.at AND view.virtual.start.at <= view.virtual.start.max *> IF view.virtual.start.at # at THEN Dirtied(view, 0, 0, FALSE); END; END; VTReal.SetStart(view, view.virtual.start.at, view.virtual.start.turned); END SetStart; PROCEDUREUpdate (vt: T) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted} = VAR view: View; BEGIN view := vt.views; WHILE view # NIL DO UpdateView (view); view := view.next; END; END Update; PROCEDUREUpdateView (view: View) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted} = VAR o, i, oLines: LineNo; at, length : I; BEGIN IF NOT view.virtual.dirty THEN RETURN; END; length := view.vt.length; i := view.virtual.firstDirty; o := i; oLines := MIN(view.nLines, view.virtual.lines + 1); IF i = 0 THEN at := view.virtual.start.at; ELSE at := view.virtual.line[i - 1].virtualLine.to; END; LOOP IF i = view.nLines THEN view.virtual.lines := i; view.virtual.line[i].virtualLine.from := at; EXIT; END; WHILE (o < oLines) AND (NOT view.virtual.line[o].virtualLine.valid OR (view.virtual.line[o].virtualLine.from < at)) DO o := o + 1; END; IF (o < oLines) AND view.virtual.line[o].virtualLine.valid AND (view.virtual.line[o].virtualLine.from = at) THEN IF (i >= view.virtual.firstAfter) AND (i = o) THEN EXIT; END; view.newVirtual.line[i] := view.virtual.line[o]; ELSE WITH line = view.newVirtual.line[i] DO line.virtualLine.from := at; line.virtualLine.to := VTBase.ComputeLine( view, view.lineWidth, at, line.virtualLine.max, line.virtualLine.turned, line.virtualLine.width); line.virtualLine.valid := TRUE; END; END; WITH line = view.newVirtual.line[i] DO at := line.virtualLine.to; IF at = line.virtualLine.from THEN view.virtual.lines := i; i := i + 1; EXIT; END; END; i := i + 1; END; FOR j := view.virtual.firstDirty TO i - 1 DO view.virtual.line[j] := view.newVirtual.line[j]; END; FOR i := view.virtual.lines + 1 TO view.virtual.firstAfter DO view.virtual.line[i] := view.virtual.line[view.virtual.lines]; END; view.virtual.dirty := FALSE; view.virtual.bodyDirty := FALSE; view.virtual.firstDirty := view.nLines; view.virtual.firstAfter := 0; END UpdateView; PROCEDUREInit (view: View; start: I) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted} = BEGIN view.virtual.start.at := start; Bad (view); END Init;
Like Real.Bad, but invalidates the virtual side. Used on initial setup, or when the width has changed.
PROCEDUREBad (view: View) RAISES {Rd.EndOfFile, Rd.Failure, Thread.Alerted} = VAR i: INTEGER; BEGIN WITH z_135 = view^ DO FOR z_136 := 0 TO z_135.nLines - 1 DO i := z_136; z_135.virtual.line[i].virtualLine.valid := FALSE; END; z_135.virtual.lines := 0; z_135.virtual.dirty := TRUE; z_135.virtual.bodyDirty := TRUE; z_135.virtual.firstDirty := 0; z_135.virtual.firstAfter := z_135.nLines; SetStart (view, z_135.virtual.start.at); END; END Bad; PROCEDUREResize (view: View; n: CARDINAL) RAISES {} = VAR i: CARDINAL; BEGIN WITH z_137 = view^ DO IF z_137.virtual.lines < n THEN FOR z_138 := z_137.virtual.lines TO n - 1 DO i := z_138; z_137.virtual.line[i].virtualLine.valid := FALSE; END; z_137.virtual.dirty := TRUE; z_137.virtual.bodyDirty := TRUE; z_137.virtual.firstDirty := MIN (z_137.virtual.lines, z_137.virtual.firstDirty); z_137.virtual.firstAfter := MAX (n, z_137.virtual.firstAfter); ELSIF z_137.virtual.lines > n THEN z_137.virtual.lines := n; z_137.virtual.firstDirty := MIN (z_137.virtual.firstDirty, n); z_137.virtual.firstAfter := MIN (z_137.virtual.firstAfter, n); END; END; END Resize;
Utility
PROCEDUREDirtied (view: View; i: LineNo; n: CARDINAL; bodyDirty: BOOLEAN := TRUE) RAISES {} = BEGIN WITH z_139 = view^ DO z_139.virtual.dirty := TRUE; IF bodyDirty THEN z_139.virtual.bodyDirty := TRUE; END; z_139.virtual.firstDirty := MIN (z_139.virtual.firstDirty, i); z_139.virtual.firstAfter := MAX (z_139.virtual.firstAfter, i + n); END; END Dirtied; BEGIN END VTVirtual.