<> <
>
    <>
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    <>
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    DIRECTORY
        IO USING [PutFR, int],
        TextEdit USING [Size],
        TiogaButtons USING [TextNodeRef],
        TiogaOps USING [GetSelection, StepForward],
        TiogaOpsDefs USING [Location, Ref],
        ViewerClasses USING [Viewer],
        ViewerEvents USING [EventRegistration, EventProc, RegisterEventProc, UnRegisterEventProc],
        VoiceInText USING [DebugRope],
        VoiceViewers USING [VoiceViewerInfo, voiceViewerInfoList],
        SourceMarkerTracking;
            <<>>
    SourceMarkerTrackingImpl: CEDAR PROGRAM IMPORTS IO, TextEdit, TiogaButtons, TiogaOps, ViewerEvents, VoiceInText, VoiceViewers 
    EXPORTS SourceMarkerTracking = BEGIN


    <>

    ViewerAndDestroyProc: TYPE = RECORD [
        viewer: ViewerClasses.Viewer,
        destroyProc: ViewerEvents.EventRegistration
    ];
    registeredViewerList: LIST OF ViewerAndDestroyProc;
        <>

    RegisterViewer: PUBLIC PROC [viewer: ViewerClasses.Viewer] = {
        <>
    alreadyInList: BOOLEAN _ FALSE;
    FOR l: LIST OF ViewerAndDestroyProc _ registeredViewerList, l.rest WHILE l # NIL AND ~alreadyInList DO IF l.first.viewer = viewer 
    THEN alreadyInList _ TRUE ENDLOOP;

    IF ~alreadyInList THEN
    {  newEntry: ViewerAndDestroyProc _ [viewer, ViewerEvents.RegisterEventProc[
              proc: DestroyViewerEvent, event: destroy, filter: viewer, before: TRUE]];
    registeredViewerList _ CONS [newEntry, registeredViewerList]
    }
};

DestroyViewerEvent: ViewerEvents.EventProc = { 
firstEntry: BOOLEAN _ viewer = registeredViewerList.first.viewer;
previousEntry: LIST OF ViewerAndDestroyProc _ registeredViewerList;
IF ~firstEntry THEN WHILE previousEntry.rest.first.viewer # viewer DO previousEntry _ previousEntry.rest ENDLOOP; -- if this runs 
off the end then something has gone seriously wrong

ViewerEvents.UnRegisterEventProc[(IF firstEntry THEN registeredViewerList ELSE previousEntry.rest).first.destroyProc, destroy];
IF firstEntry THEN registeredViewerList _ registeredViewerList.rest ELSE previousEntry.rest _ previousEntry.rest.rest;

RemoveParentPointersTo[viewer];
};

RemoveParentPointersTo: PUBLIC PROC [viewer: ViewerClasses.Viewer] = {
FOR info: VoiceViewers.VoiceViewerInfo _ VoiceViewers.voiceViewerInfoList, info.nextInfoRec WHILE info # NIL DO
IF info.parentViewer = viewer THEN
{  info.parentViewer _ NIL;
VoiceInText.DebugRope[IO.PutFR["detaching parent link for voice viewer %d\n", IO.int[info.viewerNumber]]]
}
ENDLOOP
};


<>


TrackDeletes: PUBLIC PROC = {
<>
<>
viewer: ViewerClasses.Viewer;
start, end, current: TiogaOpsDefs.Location;
infoList: LIST OF VoiceViewers.VoiceViewerInfo _ NIL;

SeverLinks: PROC [node: TiogaOpsDefs.Ref, from, to: INT] = {
FOR l: LIST OF VoiceViewers.VoiceViewerInfo _ infoList, l.rest WHILE l # NIL DO
IF l.first.positionInParent.node = node AND l.first.positionInParent.where IN [from..to]
THEN
{  l.first.parentViewer _ NIL;
VoiceInText.DebugRope[IO.PutFR["detaching parent link for voice viewer %d\n", IO.int[l.first.viewerNumber]]]
}
ENDLOOP
};

[viewer: viewer, start: start, end: end] _ TiogaOps.GetSelection[];
FOR info: VoiceViewers.VoiceViewerInfo _ VoiceViewers.voiceViewerInfoList, info.nextInfoRec WHILE info # NIL DO IF 
info.parentViewer = viewer THEN infoList _ CONS [info, infoList] ENDLOOP;
IF infoList = NIL THEN RETURN;
<<>>
<>

IF start.node = end.node 
    THEN SeverLinks[start.node, start.where, end.where]
    ELSE
    {  current _ start;
        SeverLinks[current.node, current.where, TextEdit.Size[TiogaButtons.TextNodeRef[current.node]]-1];
        DO
            current.node _ TiogaOps.StepForward[current.node];
            IF current.node = end.node THEN
            {  SeverLinks[current.node, 0, end.where];
                EXIT
            }
            ELSE  SeverLinks[current.node, 0, TextEdit.Size[TiogaButtons.TextNodeRef[current.node]]-1]
        ENDLOOP
    };

    {  positionAdjustment: INT _ end.where - start.where + 1;
        FOR l: LIST OF VoiceViewers.VoiceViewerInfo _ infoList, l.rest WHILE l # NIL DO
        IF l.first.positionInParent.node = end.node AND l.first.positionInParent.where > end.where
        THEN l.first.positionInParent _ [start.node, l.first.positionInParent.where - positionAdjustment]
    ENDLOOP
    }
    };

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END.