private void RecordChange(TextChangeRange textChangeRange, SyntaxNode removedNode, SyntaxNode insertedNode)
{
if (_changes.Count > 0)
{
var last = _changes[_changes.Count - 1];
if (last.Range.Span.End == textChangeRange.Span.Start)
{
// merge changes...
last.OldNodes?.Enqueue(removedNode);
last.NewNodes?.Enqueue(insertedNode);
_changes[_changes.Count - 1] = new ChangeRecord(
new TextChangeRange(new TextSpan(last.Range.Span.Start, last.Range.Span.Length + textChangeRange.Span.Length), last.Range.NewLength + textChangeRange.NewLength),
last.OldNodes ?? CreateQueue(removedNode),
last.NewNodes ?? CreateQueue(insertedNode));
return;
}
Debug.Assert(textChangeRange.Span.Start >= last.Range.Span.End);
}
_changes.Add(new ChangeRecord(textChangeRange, CreateQueue(removedNode), CreateQueue(insertedNode)));
// Local Functions
Queue <SyntaxNode> CreateQueue(SyntaxNode nodeOrToken)
{
var queue = new Queue <SyntaxNode>();
queue.Enqueue(nodeOrToken);
return(queue);
}
}
private List <ChangeRangeWithText> ReduceChanges(List <ChangeRecord> changeRecords)
{
var textChanges = new List <ChangeRangeWithText>(changeRecords.Count);
var oldText = new StringBuilder();
var newText = new StringBuilder();
foreach (var cr in changeRecords)
{
// try to reduce change range by finding common characters
if (cr.Range.Span.Length > 0 && cr.Range.NewLength > 0)
{
var range = cr.Range;
CopyText(cr.OldNodes, oldText);
CopyText(cr.NewNodes, newText);
int commonLeadingCount;
int commonTrailingCount;
GetCommonEdgeLengths(oldText, newText, out commonLeadingCount, out commonTrailingCount);
// did we have any common leading or trailing characters between the strings?
if (commonLeadingCount > 0 || commonTrailingCount > 0)
{
range = new TextChangeRange(
new TextSpan(range.Span.Start + commonLeadingCount, range.Span.Length - (commonLeadingCount + commonTrailingCount)),
range.NewLength - (commonLeadingCount + commonTrailingCount));
if (commonTrailingCount > 0)
{
newText.Remove(newText.Length - commonTrailingCount, commonTrailingCount);
}
if (commonLeadingCount > 0)
{
newText.Remove(0, commonLeadingCount);
}
}
// only include adjusted change if there is still a change
if (range.Span.Length > 0 || range.NewLength > 0)
{
textChanges.Add(new ChangeRangeWithText(range, _computeNewText ? newText.ToString() : null));
}
}
else
{
// pure inserts and deletes
textChanges.Add(new ChangeRangeWithText(cr.Range, _computeNewText ? GetText(cr.NewNodes) : null));
}
}
return(textChanges);
}
public ChangeRangeWithText(TextChangeRange range, string newText)
{
this.Range = range;
this.NewText = newText;
}
internal ChangeRecord(TextChangeRange range, Queue <SyntaxNode> oldNodes, Queue <SyntaxNode> newNodes)
{
this.Range = range;
this.OldNodes = oldNodes;
this.NewNodes = newNodes;
}