private VisualTextLine Cut(VisualTextLine line, int startIndex, int? count = null) {
var substringLength = count == null ? line.Length - startIndex : count.Value;
if (line is CollapsedVisualTextLine) {
var charInfos = Enumerable.Range(startIndex, substringLength).Select(index => line.GetCharInfoAt(index));
if (charInfos.Any(info => !info.IsCharacter)) {
return GetPartialLineBeforeCollapse(charInfos, line, startIndex, substringLength);
} else {
return GetPartialLineAfterCollapse(line, startIndex, substringLength);
}
} else {
return CutStandardLine(line, startIndex, substringLength);
}
}
private int[] GetCollapseSelectionRange(TextPosition clickPosition, VisualTextLine activeLine, int lineLength) {
var startColumn = clickPosition.Column;
var endColumn = clickPosition.Column;
if (endColumn + 1 <= lineLength) {
endColumn += 1;
} else {
startColumn -= 1;
}
// move left from current position
for (var i = clickPosition.Column; i >= 0; i--) {
var charInfo = activeLine.GetCharInfoAt(i);
if (!charInfo.IsCharacter && !char.IsLetterOrDigit(charInfo.Text[0])) {
startColumn = i;
} else {
break;
}
}
// move right from current position
for (var i = clickPosition.Column; i < lineLength; i++) {
var charInfo = activeLine.GetCharInfoAt(i);
if (!charInfo.IsCharacter && !char.IsLetterOrDigit(charInfo.Text[0])) {
endColumn = i + 1;
} else {
break;
}
}
return new[] { startColumn, endColumn };
}