/// <summary>
/// Computes line starts faster given already computed line starts from text before the change.
/// </summary>
protected override TextLineCollection GetLinesCore()
{
SourceText oldText;
TextLineCollection oldLineInfo;
if (!_info.WeakOldText.TryGetTarget(out oldText) || !oldText.TryGetLines(out oldLineInfo))
{
// no old line starts? do it the hard way.
return(base.GetLinesCore());
}
// compute line starts given changes and line starts already computed from previous text
var lineStarts = ArrayBuilder <int> .GetInstance();
lineStarts.Add(0);
// position in the original document
var position = 0;
// delta generated by already processed changes (position in the new document = position + delta)
var delta = 0;
// true if last segment ends with CR and we need to check for CR+LF code below assumes that both CR and LF are also line breaks alone
var endsWithCR = false;
foreach (var change in _info.ChangeRanges)
{
// include existing line starts that occur before this change
if (change.Span.Start > position)
{
if (endsWithCR && _newText[position + delta] == '\n')
{
// remove last added line start (it was due to previous CR)
// a new line start including the LF will be added next
lineStarts.RemoveLast();
}
var lps = oldLineInfo.GetLinePositionSpan(TextSpan.FromBounds(position, change.Span.Start));
for (int i = lps.Start.Line + 1; i <= lps.End.Line; i++)
{
lineStarts.Add(oldLineInfo[i].Start + delta);
}
endsWithCR = oldText[change.Span.Start - 1] == '\r';
// in case change is inserted between CR+LF we treat CR as line break alone,
// but this line break might be retracted and replaced with new one in case LF is inserted
if (endsWithCR && change.Span.Start < oldText.Length && oldText[change.Span.Start] == '\n')
{
lineStarts.Add(change.Span.Start + delta);
}
}
// include line starts that occur within newly inserted text
if (change.NewLength > 0)
{
var changeStart = change.Span.Start + delta;
var text = GetSubText(new TextSpan(changeStart, change.NewLength));
if (endsWithCR && text[0] == '\n')
{
// remove last added line start (it was due to previous CR)
// a new line start including the LF will be added next
lineStarts.RemoveLast();
}
// Skip first line (it is always at offset 0 and corresponds to the previous line)
for (int i = 1; i < text.Lines.Count; i++)
{
lineStarts.Add(changeStart + text.Lines[i].Start);
}
endsWithCR = text[change.NewLength - 1] == '\r';
}
position = change.Span.End;
delta += change.NewLength - change.Span.Length;
}
// include existing line starts that occur after all changes
if (position < oldText.Length)
{
if (endsWithCR && _newText[position + delta] == '\n')
{
// remove last added line start (it was due to previous CR)
// a new line start including the LF will be added next
lineStarts.RemoveLast();
}
var lps = oldLineInfo.GetLinePositionSpan(TextSpan.FromBounds(position, oldText.Length));
for (int i = lps.Start.Line + 1; i <= lps.End.Line; i++)
{
lineStarts.Add(oldLineInfo[i].Start + delta);
}
}
return(new LineInfo(this, lineStarts.ToArrayAndFree()));
}
public override SourceText GetSubText(TextSpan span)
{
return(_newText.GetSubText(span));
}
/// <summary>
/// Convert a <see cref="LinePositionSpan"/> to <see cref="TextSpan"/>.
/// </summary>
/// <param name="span"></param>
public TextSpan GetTextSpan(LinePositionSpan span)
{
return(TextSpan.FromBounds(GetPosition(span.Start), GetPosition(span.End)));
}
public override string ToString(TextSpan span)
{
return(_newText.ToString(span));
}
/// <summary>
/// Convert a <see cref="TextSpan"/> to a <see cref="LinePositionSpan"/>.
/// </summary>
/// <param name="span"></param>
public LinePositionSpan GetLinePositionSpan(TextSpan span)
{
return(new LinePositionSpan(GetLinePosition(span.Start), GetLinePosition(span.End)));
}
