/// <summary>
/// Maps a position in the source space to the corresponding position in the target space.
/// </summary>
public int GetTargetPosition(int sourcePosition, PositionBias bias = PositionBias.Right)
{
int targetPosition = sourcePosition;
foreach (var edit in _edits)
{
targetPosition = Translate(
targetPosition,
edit.Start,
edit.DeleteLength,
edit.InsertLength,
bias);
}
return(targetPosition);
}
/// <summary>
/// Reverse maps a position from the target space to the correpsonding position in the source space.
/// </summary>
public int GetSourcePosition(int targetPosition, PositionBias bias = PositionBias.Right)
{
int sourcePosition = targetPosition;
for (int i = _edits.Count - 1; i >= 0; i--)
{
var edit = _edits[i];
// since we are doing the reverse operation
// deletes are inserts and inserts are deletes
sourcePosition = Translate(
position: sourcePosition,
start: edit.Start,
deleteLength: edit.InsertLength,
insertLength: edit.DeleteLength,
bias: bias);
}
return(sourcePosition);
}
/// <summary>
/// Translate a position across an edit
/// </summary>
private static int Translate(int position, int start, int deleteLength, int insertLength, PositionBias bias)
{
if (deleteLength > 0 && position > start)
{
if (position > start + deleteLength)
{
// after deleted range, adjust downward
position -= deleteLength;
}
else
{
// inside deleted range, adjust to start
position = start;
}
}
if (insertLength > 0)
{
// if after the insert position, adjust upward
// or at the insert position and bias is toward right, also adjust upward
if (position > start || (bias == PositionBias.Right && position == start))
{
position += insertLength;
}
}
return(position);
}
/// <summary>
/// Gets the position in the original text corresponding to the position in the current text.
/// If current position corresponds to a region of the text that was inserted, it will return the position
/// at the start of where change occurred.
/// </summary>
public int GetOriginalPosition(int currentPosition, PositionBias bias = PositionBias.Right)
{
return(this._map.GetSourcePosition(currentPosition, bias));
}
/// <summary>
/// Gets the position in the current text corresponding to the position in the original text.
/// If original position corresponds to a region of text that was removed or replaced, it will return the position
/// at the start of where the change occurred.
/// </summary>
public int GetCurrentPosition(int originalPosition, PositionBias bias = PositionBias.Right)
{
return(this._map.GetTargetPosition(originalPosition, bias));
}
