public static List <Patch3Set> Diff3MergeIndices(string[] a, string[] o, string[] b)
{
// Given three files, A, O, and B, where both A and B are
// independently derived from O, returns a fairly complicated
// internal representation of merge decisions it's taken. The
// interested reader may wish to consult
//
// Sanjeev Khanna, Keshav Kunal, and Benjamin C. Pierce. "A
// Formal Investigation of Diff3." In Arvind and Prasad,
// editors, Foundations of Software Technology and Theoretical
// Computer Science (FSTTCS), December 2007.
//
// (http://www.cis.upenn.edu/~bcpierce/papers/diff3-short.pdf)
var m1 = Diff.DiffIndices(o, a);
var m2 = Diff.DiffIndices(o, b);
var hunks = new List <Diff3Set>();
for (int i = 0; i < m1.Count; i++)
{
AddHunk(m1[i], Side.Left, hunks);
}
for (int i = 0; i < m2.Count; i++)
{
AddHunk(m2[i], Side.Right, hunks);
}
hunks.Sort();
var result = new List <Patch3Set>();
var commonOffset = 0;
for (var hunkIndex = 0; hunkIndex < hunks.Count; hunkIndex++)
{
var firstHunkIndex = hunkIndex;
var hunk = hunks[hunkIndex];
var regionLhs = hunk.File1Offset;
var regionRhs = regionLhs + hunk.File1Length;
while (hunkIndex < hunks.Count - 1)
{
var maybeOverlapping = hunks[hunkIndex + 1];
var maybeLhs = maybeOverlapping.File1Offset;
if (maybeLhs > regionRhs)
{
break;
}
regionRhs = Math.Max(regionRhs, maybeLhs + maybeOverlapping.File1Length);
hunkIndex++;
}
CopyCommon2(regionLhs, ref commonOffset, result);
if (firstHunkIndex == hunkIndex)
{
// The "overlap" was only one hunk long, meaning that
// there's no conflict here. Either a and o were the
// same, or b and o were the same.
if (hunk.File2Length > 0)
{
result.Add(new Patch3Set
{
Side = hunk.Side,
Offset = hunk.File2Offset,
Length = hunk.File2Length
});
}
}
else
{
// A proper conflict. Determine the extents of the
// regions involved from a, o and b. Effectively merge
// all the hunks on the left into one giant hunk, and
// do the same for the right; then, correct for skew
// in the regions of o that each Side changed, and
// report appropriate spans for the three sides.
var regions = new Dictionary <Side, ConflictRegion>
{
{
Side.Left,
new ConflictRegion
{
File1RegionStart = a.Length,
File1RegionEnd = -1,
File2RegionStart = o.Length,
File2RegionEnd = -1
}
},
{
Side.Right,
new ConflictRegion
{
File1RegionStart = b.Length,
File1RegionEnd = -1,
File2RegionStart = o.Length,
File2RegionEnd = -1
}
}
};
for (int i = firstHunkIndex; i <= hunkIndex; i++)
{
hunk = hunks[i];
var side = hunk.Side;
var r = regions[side];
var oLhs = hunk.File1Offset;
var oRhs = oLhs + hunk.File1Length;
var abLhs = hunk.File2Offset;
var abRhs = abLhs + hunk.File2Length;
r.File1RegionStart = Math.Min(abLhs, r.File1RegionStart);
r.File1RegionEnd = Math.Max(abRhs, r.File1RegionEnd);
r.File2RegionStart = Math.Min(oLhs, r.File2RegionStart);
r.File2RegionEnd = Math.Max(oRhs, r.File2RegionEnd);
}
var aLhs = regions[Side.Left].File1RegionStart + (regionLhs - regions[Side.Left].File2RegionStart);
var aRhs = regions[Side.Left].File1RegionEnd + (regionRhs - regions[Side.Left].File2RegionEnd);
var bLhs = regions[Side.Right].File1RegionStart + (regionLhs - regions[Side.Right].File2RegionStart);
var bRhs = regions[Side.Right].File1RegionEnd + (regionRhs - regions[Side.Right].File2RegionEnd);
result.Add(new Patch3Set
{
Side = Side.Conflict,
Offset = aLhs,
Length = aRhs - aLhs,
ConflictOldOffset = regionLhs,
ConflictOldLength = regionRhs - regionLhs,
ConflictRightOffset = bLhs,
ConflictRightLength = bRhs - bLhs
});
}
commonOffset = regionRhs;
}
CopyCommon2(o.Length, ref commonOffset, result);
return(result);
}
