/// <summary>
/// Constructs a Text Change object.
/// </summary>
/// <param name="oldPosition">
/// The character position in the TextBuffer at which the text change happened.
/// </param>
/// <param name="oldText">
/// The text in the buffer that was replaced.
/// </param>
/// <param name="newText">
/// The text that replaces the old text.
/// </param>
/// <param name="boundaryConditions">
/// Information about neighboring line break characters.
/// </param>
public TextChange(int oldPosition, ChangeString oldText, ChangeString newText, LineBreakBoundaryConditions boundaryConditions)
{
if (oldPosition < 0)
{
throw new ArgumentOutOfRangeException("oldPosition");
}
_oldPosition = oldPosition;
_newPosition = oldPosition;
_oldText = oldText;
_newText = newText;
_lineBreakBoundaryConditions = boundaryConditions;
}
/// <summary>
/// Constructs a Text Change object.
/// </summary>
/// <param name="oldPosition">
/// The character position in the TextBuffer at which the text change happened.
/// </param>
/// <param name="oldText">
/// The text in the buffer that was replaced.
/// </param>
/// <param name="newText">
/// The text that replaces the old text.
/// </param>
/// <param name="boundaryConditions">
/// Information about neighboring line break characters.
/// </param>
public TextChange(int oldPosition, StringRebuilder oldText, StringRebuilder newText, LineBreakBoundaryConditions boundaryConditions)
{
if (oldPosition < 0)
{
throw new ArgumentOutOfRangeException(nameof(oldPosition));
}
_oldPosition = oldPosition;
_newPosition = oldPosition;
_oldText = oldText;
_newText = newText;
_lineBreakBoundaryConditions = boundaryConditions;
}
private static LineBreakBoundaryConditions ComputeLineBreakBoundaryConditions(ITextSnapshot currentSnapshot, int position, int oldLength)
{
LineBreakBoundaryConditions conditions = LineBreakBoundaryConditions.None;
if (position > 0 && currentSnapshot[position - 1] == '\r')
{
conditions = LineBreakBoundaryConditions.PrecedingReturn;
}
int end = position + oldLength;
if (end < currentSnapshot.Length && currentSnapshot[end] == '\n')
{
conditions = conditions | LineBreakBoundaryConditions.SucceedingNewline;
}
return(conditions);
}
static public int ComputeLineCountDelta(LineBreakBoundaryConditions boundaryConditions, StringRebuilder oldText, StringRebuilder newText)
{
int delta = 0;
delta -= oldText.LineBreakCount;
delta += newText.LineBreakCount;
if ((boundaryConditions & LineBreakBoundaryConditions.PrecedingReturn) != 0)
{
if (oldText.FirstCharacter == '\n')
{
delta++;
}
if (newText.FirstCharacter == '\n')
{
delta--;
}
}
if ((boundaryConditions & LineBreakBoundaryConditions.SucceedingNewline) != 0)
{
if (oldText.LastCharacter == '\r')
{
delta++;
}
if (newText.LastCharacter == '\r')
{
delta--;
}
}
if ((oldText.Length == 0) &&
((boundaryConditions & LineBreakBoundaryConditions.PrecedingReturn) != 0) &&
((boundaryConditions & LineBreakBoundaryConditions.SucceedingNewline) != 0))
{
// return and newline were adjacent before and were separated by the insertion
delta++;
}
if ((newText.Length == 0) &&
((boundaryConditions & LineBreakBoundaryConditions.PrecedingReturn) != 0) &&
((boundaryConditions & LineBreakBoundaryConditions.SucceedingNewline) != 0))
{
// return and newline were separated before and were made adjacent by the deletion
delta--;
}
return(delta);
}
/// <summary>
/// Compute the impact of a change that substitutes <paramref name="newText"/> for <paramref name="oldText"/> in the
/// context described by the <paramref name="boundaryConditions"/>.
/// </summary>
/// <param name="boundaryConditions">Immediate surroundings of the change with respect to compound line breaks.</param>
/// <param name="oldText">The replaced text.</param>
/// <param name="newText">The newly inserted text.</param>
/// <returns></returns>
static public int ComputeLineCountDelta(LineBreakBoundaryConditions boundaryConditions, ChangeString oldText, ChangeString newText)
{
int delta = 0;
delta -= oldText.ComputeLineBreakCount();
delta += newText.ComputeLineBreakCount();
if ((boundaryConditions & LineBreakBoundaryConditions.PrecedingReturn) != 0)
{
if (oldText.Length > 0 && oldText[0] == '\n')
{
delta++;
}
if (newText.Length > 0 && newText[0] == '\n')
{
delta--;
}
}
if ((boundaryConditions & LineBreakBoundaryConditions.SucceedingNewline) != 0)
{
if (oldText.Length > 0 && oldText[oldText.Length - 1] == '\r')
{
delta++;
}
if (newText.Length > 0 && newText[newText.Length - 1] == '\r')
{
delta--;
}
}
if ((oldText.Length == 0) &&
((boundaryConditions & LineBreakBoundaryConditions.PrecedingReturn) != 0) &&
((boundaryConditions & LineBreakBoundaryConditions.SucceedingNewline) != 0))
{
// return and newline were adjacent before and were separated by the insertion
delta++;
}
if ((newText.Length == 0) &&
((boundaryConditions & LineBreakBoundaryConditions.PrecedingReturn) != 0) &&
((boundaryConditions & LineBreakBoundaryConditions.SucceedingNewline) != 0))
{
// return and newline were separated before and were made adjacent by the deletion
delta--;
}
return(delta);
}
private static LineBreakBoundaryConditions ComputeBoundaryConditions(TextChange outerChange, ChangeString oldText, Span leftSpan)
{
LineBreakBoundaryConditions bc = LineBreakBoundaryConditions.None;
if (leftSpan.Start == 0)
{
bc = (outerChange.LineBreakBoundaryConditions & LineBreakBoundaryConditions.PrecedingReturn);
}
else if (oldText[leftSpan.Start - 1] == '\r')
{
bc = LineBreakBoundaryConditions.PrecedingReturn;
}
if (leftSpan.End == oldText.Length)
{
bc |= (outerChange.LineBreakBoundaryConditions & LineBreakBoundaryConditions.SucceedingNewline);
}
else if (oldText[leftSpan.End] == '\n')
{
bc |= LineBreakBoundaryConditions.SucceedingNewline;
}
return(bc);
}
internal TextChange(int oldPosition, string oldText, string newText, LineBreakBoundaryConditions boundaryConditions)
: this(oldPosition, StringRebuilder.Create(oldText), StringRebuilder.Create(newText), boundaryConditions)
{
}
