private void Validate(ref LineViewSnapshot snapshot, string paramName)
{
if (_options.SnapshotsComparer.Equals(snapshot, default(LineViewSnapshot)))
{
throw new ArgumentNullException(nameof(paramName));
}
}
public bool TryRedo(LineViewSnapshot currentSnapshot, out LineViewSnapshot nextSnapshot)
{
Validate(ref currentSnapshot, nameof(currentSnapshot));
TryAddSnapshotInternal(ref currentSnapshot);
if (_iterator.MoveToNext())
{
nextSnapshot = _iterator.Current;
return(true);
}
nextSnapshot = default(LineViewSnapshot);
return(false);
}
public bool TryUndo(LineViewSnapshot currentSnapshot, out LineViewSnapshot prevSnapshot)
{
Validate(ref currentSnapshot, nameof(currentSnapshot));
TryAddSnapshotInternal(ref currentSnapshot);
if (_iterator.MoveToPrev())
{
prevSnapshot = _iterator.Current;
return(true);
}
prevSnapshot = default(LineViewSnapshot);
return(false);
}
private bool TryAddSnapshotInternal(ref LineViewSnapshot snapshot)
{
if (EqualsToCurrentSnapshot(ref snapshot))
{
return(false);
}
if (_iterator.HasNext())
{
_snapshots.TrimTo(_iterator.Index + 1);
}
_snapshots.Add(snapshot);
_iterator.MoveToLast();
return(true);
}
private bool EqualsToCurrentSnapshot(ref LineViewSnapshot snapshot)
{
return(_snapshots.Count > 0 &&
_options.SnapshotsComparer.Equals(snapshot, _iterator.Current));
}
public bool TryAddSnapshot(LineViewSnapshot snapshot)
{
Validate(ref snapshot, nameof(snapshot));
return(TryAddSnapshotInternal(ref snapshot));
}