internal static Lcs Get(List <JToken> left, List <JToken> right, ItemMatch match)
{
var matrix = LcsInternal(left, right, match);
var result = Backtrack(matrix, left, right, left.Count, right.Count, match);
return(result);
}
private static int[,] LcsInternal(List <JToken> left, List <JToken> right, ItemMatch match)
{
var arr = new int[left.Count + 1, right.Count + 1];
for (int i = 1; i <= left.Count; i++)
{
for (int j = 1; j <= right.Count; j++)
{
if (match.Match(left[i - 1], right[j - 1]))
{
arr[i, j] = arr[i - 1, j - 1] + 1;
}
else
{
arr[i, j] = Math.Max(arr[i - 1, j], arr[i, j - 1]);
}
}
}
return(arr);
}
private static Lcs Backtrack(int[,] matrix, List <JToken> left, List <JToken> right, int li, int ri, ItemMatch match)
{
var result = new Lcs();
for (int i = 1, j = 1; i <= li && j <= ri;)
{
// If the JSON tokens at the same position are both Objects or both Arrays, we just say they
// are the same even if they are not, because we can package smaller deltas than an entire
// object or array replacement by doing object to object or array to array diff.
if (match.Match(left[i - 1], right[j - 1]))
{
result.Sequence.Add(left[i - 1]);
result.Indices1.Add(i - 1);
result.Indices2.Add(j - 1);
i++;
j++;
continue;
}
if (matrix[i, j - 1] > matrix[i - 1, j])
{
i++;
}
else
{
j++;
}
}
return(result);
}
