public static DiffChain ConstructBackwardDiffChain(FileSnapshot a, FileSnapshot next, int right)
{
DiffChain backward = new DiffChain();
backward.Start = right;
backward.StartSnap = next;
backward.EndSnap = a;
backward.End = null;
int?left = next.GetRightToLeft(right); // left is a's right
if (left == null)
{
backward.Kind = DiffChainType.Null;
return(backward);
}
//left++; // backward chaining drift?
var aStatus = backward.RightFromLeftStatus(a, left.Value);
var nextStatus = backward.SelfStatusFromRight(next, right);
var chainType = backward.DetermineChainType(aStatus, nextStatus);
backward.Kind = chainType;
backward.End = left;
return(backward);
}
protected void Chain()
{
var a = m_snapshots.FirstOrDefault();
if (a == null)
{
return;
}
foreach (var next in m_snapshots.Skip(1))
{
for (int right = 0; right < a.RightTextLines.Count; right++)
{
var forwardChain = DiffChain.ConstructForwardDiffChain(a, next, right);
a.ForwardChains.Add(forwardChain);
}
for (int right = 0; right < next.RightTextLines.Count; right++)
{
var backChain = DiffChain.ConstructBackwardDiffChain(a, next, right);
next.BackChains.Add(backChain);
}
a = next;
}
// Verify
var prevRightSideCount = m_snapshots.First().RightTextLines.Count;
var prevForwardChainCount = m_snapshots.First().ForwardChains.Count;
a = m_snapshots.First();
foreach (var next in m_snapshots.Skip(1))
{
//int backChainCount = next.BackChains.Where( chain => chain.Kind != DiffChainType.Null && chain.End != null ).Count();
//if (backChainCount != prevRightSideCount)
//{
// throw new Exception("Invalid State: " + backChainCount + " != " + prevRightSideCount);
//}
//int count = next.Differences.Where( d => d.DifferenceType == DifferenceType.Add ).Select( d => d.Right.Length ).Sum();
//if (prevForwardChainCount != next.RightTextLines.Count - count )
//{
// throw new Exception("Invalid State: " + prevForwardChainCount + " != " + next.RightTextLines.Count);
//}
//a = next;
//prevRightSideCount = next.RightTextLines.Count;
//prevForwardChainCount = next.ForwardChains.Count;
}
}
public static DiffChain ConstructForwardDiffChain(FileSnapshot a, FileSnapshot next, int right)
{
try
{
var chain = new DiffChain()
{
};
var aStatus = chain.SelfStatusFromRight(a, right);
var nextStatus = chain.LeftFromRightStatus(next, right);
var chainType = chain.DetermineChainType(aStatus, nextStatus);
chain.Kind = chainType;
chain.Start = right;
chain.End = next.GetLeftToRight(right);
chain.StartSnap = a;
chain.EndSnap = next;
return(chain);
}
catch (Exception ex)
{
Trace.WriteLine(ex.Message);
return(null);
}
}
