
<<TiogaSelectionAllocImpl.mesa    Edited by Paxton on June 17, 1983 1:32 pm>>
<<>>
DIRECTORY
TiogaDocument USING [Selection, SelectionRec],
TiogaSelection;

TiogaSelectionAllocImpl: CEDAR MONITOR EXPORTS TiogaSelection = BEGIN

OPEN TiogaSelection;

pSel: PUBLIC TiogaDocument.Selection _ Create[];

sSel: PUBLIC TiogaDocument.Selection _ Create[];

fSel: PUBLIC TiogaDocument.Selection _ Create[];

oldSel: PUBLIC TiogaDocument.Selection _ Create[];

nilSel: PUBLIC TiogaDocument.Selection _ Create[];

tSel1, tSel2, tSel3: TiogaDocument.Selection; -- cache of temporary selection records

Create: PUBLIC PROC RETURNS [TiogaDocument.Selection] = {
RETURN [NEW[TiogaDocument.SelectionRec]] };

Alloc: PUBLIC ENTRY PROC RETURNS [tSel: TiogaDocument.Selection] = {
ENABLE UNWIND => NULL;
IF tSel3 # NIL THEN { tSel _ tSel3; tSel3 _ NIL }
ELSE IF tSel2 # NIL THEN { tSel _ tSel2; tSel2 _ NIL }
ELSE IF tSel1 # NIL THEN { tSel _ tSel1; tSel1 _ NIL }
ELSE tSel _ Create[] };

Free: PUBLIC ENTRY PROC [tSel: TiogaDocument.Selection] = {
ENABLE UNWIND => NULL;
IF tSel3 = tSel OR tSel2 = tSel OR tSel1 = tSel THEN ERROR;
IF tSel3 = NIL THEN tSel3 _ tSel
ELSE IF tSel2 = NIL THEN tSel2 _ tSel
ELSE IF tSel1 = NIL THEN tSel1 _ tSel };

Copy: PUBLIC ENTRY PROC [source, dest: TiogaDocument.Selection] = {
ENABLE UNWIND => NULL;
dest^ _ source^ };

END.