private IEnumerable <DocumentChange <T> > GetForwardChanges(DocumentVersion <T> other)
{
// Return changes from this(inclusive) to other(exclusive).
for (DocumentVersion <T> node = this; node != other; node = node.next)
{
foreach (DocumentChange <T> change in node.changes)
{
yield return(change);
}
}
}
/// <summary>
/// Compares the age of this checkpoint to the other checkpoint.
/// </summary>
/// <remarks>This method is thread-safe.</remarks>
/// <exception cref="ArgumentException">Raised if 'other' belongs to a different document than this version.</exception>
/// <returns>-1 if this version is older than <paramref name="other"/>.
/// 0 if <c>this</c> version instance represents the same version as <paramref name="other"/>.
/// 1 if this version is newer than <paramref name="other"/>.</returns>
public int CompareAge(DocumentVersion <T> other)
{
if (other == null)
{
throw new ArgumentNullException("other");
}
DocumentVersion <T> o = other as DocumentVersion <T>;
if (o == null || provider != o.provider)
{
throw new ArgumentException("Versions do not belong to the same document");
}
// We will allow overflows, but assume that the maximum distance between checkpoints is 2^31-1.
// This is guaranteed on x86 because so many checkpoints don't fit into memory.
return(Math.Sign(unchecked (this.id - o.id)));
}
/// <summary>
/// Gets the changes from this checkpoint to the other checkpoint.
/// If 'other' is older than this checkpoint, an exception is thrown.
/// </summary>
/// <remarks>This method is thread-safe.</remarks>
/// <exception cref="ArgumentException">Raised if 'other' belongs to a different document than this checkpoint, or 'other' is older than this checkpoint.</exception>
public IEnumerable <DocumentChange <T> > GetChangesTo(DocumentVersion <T> other)
{
int result = CompareAge(other);
if (result < 0)
{
return(GetForwardChanges(other));
}
else if (result > 0)
{
return(other.GetForwardChanges(this).Reverse().Select(change => change.Invert()));
}
else
{
return(NO_CHANGES);
}
}
public DocumentChangedEvent(DocumentVersion <T> before, DocumentVersion <T> after)
{
DocumentVersionBefore = before;
DocumentVersionAfter = after;
}
/// <summary>
/// Gets whether this checkpoint belongs to the same document as the other checkpoint.
/// </summary>
/// <remarks>
/// Returns false when given <c>null</c>.
/// </remarks>
public bool BelongsToSameDocumentAs(DocumentVersion <T> other)
{
DocumentVersion <T> o = other as DocumentVersion <T>;
return(o != null && provider == o.provider);
}
/// <summary>
/// New version of an existing document
/// </summary>
internal DocumentVersion(DocumentVersion <T> prev)
{
this.provider = prev.provider;
this.id = unchecked (prev.id + 1);
}
/// <summary>
/// Get changes between older version v1 and more recent version v2 :
/// - with redundant changes applied on the same line merged in one single change
/// - with line indexes translated to be valid in the v2 document
/// - with changes sorted in the order of the line indexes in the v2 document
/// </summary>
public IList <DocumentChange <T> > GetReducedAndOrderedChangesInNewerVersion(DocumentVersion <T> other)
{
// Ensure the version received as parameter is more recent than teh current version
int result = CompareAge(other);
if (result >= 0)
{
throw new InvalidOperationException("other version must be more recent than this version");
}
// Merge the redundant changes and translate the line indexes to the last version
List <DocumentChange <T> > reducedDocumentChanges = new List <DocumentChange <T> >();
foreach (DocumentChange <T> documentChange in GetChangesTo(other))
{
switch (documentChange.Type)
{
case DocumentChangeType.DocumentCleared:
// Ignore all previous document changes : they are meaningless now that the document was completely cleared
reducedDocumentChanges.Clear();
// Add the clear event
reducedDocumentChanges.Add(documentChange);
break;
case DocumentChangeType.LineInserted:
// Recompute the line indexes of all the changes prevously applied
foreach (DocumentChange <T> documentChangeToAdjust in reducedDocumentChanges)
{
if (documentChangeToAdjust.LineIndex >= documentChange.LineIndex)
{
documentChangeToAdjust.LineIndex = documentChangeToAdjust.LineIndex + 1;
}
}
// Add the insert change
reducedDocumentChanges.Add(documentChange);
break;
case DocumentChangeType.LineUpdated:
// Check to see if this change can be merged with a previous one
bool changeAlreadyApplied = false;
foreach (DocumentChange <T> documentChangeToAdjust in reducedDocumentChanges)
{
if (documentChangeToAdjust.LineIndex == documentChange.LineIndex)
{
changeAlreadyApplied = true;
break;
}
}
if (!changeAlreadyApplied)
{
// Add the update change
reducedDocumentChanges.Add(documentChange);
}
break;
case DocumentChangeType.LineRemoved:
// Recompute the line indexes of all the changes prevously applied
DocumentChange <T> documentChangeToRemove = null;
foreach (DocumentChange <T> documentChangeToAdjust in reducedDocumentChanges)
{
if (documentChangeToAdjust.LineIndex > documentChange.LineIndex)
{
documentChangeToAdjust.LineIndex = documentChangeToAdjust.LineIndex - 1;
}
else if (documentChangeToAdjust.LineIndex == documentChange.LineIndex)
{
documentChangeToRemove = documentChangeToAdjust;
}
}
// Ignore all previous changes applied to a line now removed
if (documentChangeToRemove != null)
{
reducedDocumentChanges.Remove(documentChangeToRemove);
}
break;
}
}
// Sort all changes by line index
reducedDocumentChanges.Sort((documentChange1, documentChange2) => documentChange1.LineIndex - documentChange2.LineIndex);
return(reducedDocumentChanges);
}
