private static bool TreesAreDifferent(Block leftTree, Block rightTree, TextChange change)
{
Span changeOwner = leftTree.LocateOwner(change);
// Apply the change to the tree
if (changeOwner == null)
{
return(true);
}
changeOwner.ApplyChange(change, force: true);
// Now compare the trees
return(!Equals(leftTree, rightTree));
}
// Try to parse the change incrementally
// Partial Parsing succeeds if:
// * A single span can be identified which owns the change (i.e. it doesn't overlap multiple spans)
// * The span which owns the change has logic to accept it
// The performance of this method is crucial, since it occurs on the caller's thread (usually a UI thread).
private PartialParseResult TryPartialParse(TextChange change)
{
PartialParseResult result = PartialParseResult.Rejected;
if (CurrentParseTree != null && !_parseUnderway)
{
// Try the last change owner
if (_lastChangeOwner != null && _lastChangeOwner.OwnsChange(change))
{
result = _lastChangeOwner.ApplyChange(change);
// If the last change was provisional, then the result of this span's attempt to parse partially goes
// Otherwise, accept the change if this span accepted it, but if it didn't, just do the standard search.
if (LastResultProvisional || result.HasFlag(PartialParseResult.Accepted))
{
return(result);
}
}
// Locate the span responsible for this change
_lastChangeOwner = CurrentParseTree.LocateOwner(change);
if (LastResultProvisional)
{
// Last change owner couldn't accept this, so we must do a full reparse
result = PartialParseResult.Rejected;
}
else if (_lastChangeOwner != null)
{
result = _lastChangeOwner.ApplyChange(change);
if (result.HasFlag(PartialParseResult.AutoCompleteBlock))
{
_lastAutoCompleteSpan = _lastChangeOwner;
}
}
}
return(result);
}
