/// <summary>
/// Calculates the inverted OffsetChangeMap (used for the undo operation).
/// </summary>
public OffsetChangeMap Invert()
{
if (this == Empty)
{
return(this);
}
var newMap = new OffsetChangeMap(Count);
for (var i = Count - 1; i >= 0; i--)
{
var entry = this[i];
// swap InsertionLength and RemovalLength
newMap.Add(new OffsetChangeMapEntry(entry.Offset, entry.InsertionLength, entry.RemovalLength));
}
return(newMap);
}
/// <summary>
/// Replaces text.
/// </summary>
/// <param name="offset">The starting offset of the text to be replaced.</param>
/// <param name="length">The length of the text to be replaced.</param>
/// <param name="text">The new text.</param>
/// <param name="offsetChangeMappingType">
/// The offsetChangeMappingType determines how offsets inside the old text are mapped to the new text.
/// This affects how the anchors and segments inside the replaced region behave.
/// </param>
public void Replace(int offset, int length, ITextSource text, OffsetChangeMappingType offsetChangeMappingType)
{
if (text == null)
{
throw new ArgumentNullException("text");
}
// Please see OffsetChangeMappingType XML comments for details on how these modes work.
switch (offsetChangeMappingType)
{
case OffsetChangeMappingType.Normal:
Replace(offset, length, text, null);
break;
case OffsetChangeMappingType.KeepAnchorBeforeInsertion:
Replace(offset, length, text, OffsetChangeMap.FromSingleElement(
new OffsetChangeMapEntry(offset, length, text.TextLength, false, true)));
break;
case OffsetChangeMappingType.RemoveAndInsert:
if (length == 0 || text.TextLength == 0)
{
// only insertion or only removal?
// OffsetChangeMappingType doesn't matter, just use Normal.
Replace(offset, length, text, null);
}
else
{
var map = new OffsetChangeMap(2);
map.Add(new OffsetChangeMapEntry(offset, length, 0));
map.Add(new OffsetChangeMapEntry(offset, 0, text.TextLength));
map.Freeze();
Replace(offset, length, text, map);
}
break;
case OffsetChangeMappingType.CharacterReplace:
if (length == 0 || text.TextLength == 0)
{
// only insertion or only removal?
// OffsetChangeMappingType doesn't matter, just use Normal.
Replace(offset, length, text, null);
}
else if (text.TextLength > length)
{
// look at OffsetChangeMappingType.CharacterReplace XML comments on why we need to replace
// the last character
var entry = new OffsetChangeMapEntry(offset + length - 1, 1, 1 + text.TextLength - length);
Replace(offset, length, text, OffsetChangeMap.FromSingleElement(entry));
}
else if (text.TextLength < length)
{
var entry = new OffsetChangeMapEntry(offset + text.TextLength, length - text.TextLength, 0, true, false);
Replace(offset, length, text, OffsetChangeMap.FromSingleElement(entry));
}
else
{
Replace(offset, length, text, OffsetChangeMap.Empty);
}
break;
default:
throw new ArgumentOutOfRangeException("offsetChangeMappingType", offsetChangeMappingType, "Invalid enum value");
}
}