/// <summary>
/// Does the three way merge between a common base and two sequences.
/// </summary>
/// <param name="base">base the common base sequence</param>
/// <param name="ours">ours the first sequence to be merged</param>
/// <param name="theirs">theirs the second sequence to be merged</param>
/// <returns>the resulting content</returns>
public static MergeResult merge(Sequence @base, Sequence ours,
Sequence theirs)
{
List<Sequence> sequences = new List<Sequence>(3);
sequences.Add(@base);
sequences.Add(ours);
sequences.Add(theirs);
MergeResult result = new MergeResult(sequences);
EditList oursEdits = new MyersDiff(@base, ours).getEdits();
IteratorBase<Edit> baseToOurs = oursEdits.iterator();
EditList theirsEdits = new MyersDiff(@base, theirs).getEdits();
IteratorBase<Edit> baseToTheirs = theirsEdits.iterator();
int current = 0; // points to the next line (first line is 0) of base
// which was not handled yet
Edit oursEdit = nextEdit(baseToOurs);
Edit theirsEdit = nextEdit(baseToTheirs);
// iterate over all edits from base to ours and from base to theirs
// leave the loop when there are no edits more for ours or for theirs
// (or both)
while (theirsEdit != END_EDIT || oursEdit != END_EDIT)
{
if (oursEdit.EndA <= theirsEdit.BeginA)
{
// something was changed in ours not overlapping with any change
// from theirs. First add the common part in front of the edit
// then the edit.
if (current != oursEdit.BeginA)
{
result.add(0, current, oursEdit.BeginA,
MergeChunk.ConflictState.NO_CONFLICT);
}
result.add(1, oursEdit.BeginB, oursEdit.EndB,
MergeChunk.ConflictState.NO_CONFLICT);
current = oursEdit.EndA;
oursEdit = nextEdit(baseToOurs);
}
else if (theirsEdit.EndA <= oursEdit.BeginA)
{
// something was changed in theirs not overlapping with any
// from ours. First add the common part in front of the edit
// then the edit.
if (current != theirsEdit.BeginA)
{
result.add(0, current, theirsEdit.BeginA,
MergeChunk.ConflictState.NO_CONFLICT);
}
result.add(2, theirsEdit.BeginB, theirsEdit.EndB,
MergeChunk.ConflictState.NO_CONFLICT);
current = theirsEdit.EndA;
theirsEdit = nextEdit(baseToTheirs);
}
else
{
// here we found a real overlapping modification
// if there is a common part in front of the conflict add it
if (oursEdit.BeginA != current
&& theirsEdit.BeginA != current)
{
result.add(0, current, Math.Min(oursEdit.BeginA,
theirsEdit.BeginA), MergeChunk.ConflictState.NO_CONFLICT);
}
// set some initial values for the ranges in A and B which we
// want to handle
int oursBeginB = oursEdit.BeginB;
int theirsBeginB = theirsEdit.BeginB;
// harmonize the start of the ranges in A and B
if (oursEdit.BeginA < theirsEdit.BeginA)
{
theirsBeginB -= theirsEdit.BeginA
- oursEdit.BeginA;
}
else
{
oursBeginB -= oursEdit.BeginA - theirsEdit.BeginA;
}
// combine edits:
// Maybe an Edit on one side corresponds to multiple Edits on
// the other side. Then we have to combine the Edits of the
// other side - so in the end we can merge together two single
// edits.
//
// It is important to notice that this combining will extend the
// ranges of our conflict always downwards (towards the end of
// the content). The starts of the conflicting ranges in ours
// and theirs are not touched here.
//
// This combining is an iterative process: after we have
// combined some edits we have to do the check again. The
// combined edits could now correspond to multiple edits on the
// other side.
//
// Example: when this combining algorithm works on the following
// edits
// oursEdits=((0-5,0-5),(6-8,6-8),(10-11,10-11)) and
// theirsEdits=((0-1,0-1),(2-3,2-3),(5-7,5-7))
// it will merge them into
// oursEdits=((0-8,0-8),(10-11,10-11)) and
// theirsEdits=((0-7,0-7))
//
// Since the only interesting thing to us is how in ours and
// theirs the end of the conflicting range is changing we let
// oursEdit and theirsEdit point to the last conflicting edit
Edit nextOursEdit = nextEdit(baseToOurs);
Edit nextTheirsEdit = nextEdit(baseToTheirs);
for (; ; )
{
if (oursEdit.EndA > nextTheirsEdit.BeginA)
{
theirsEdit = nextTheirsEdit;
nextTheirsEdit = nextEdit(baseToTheirs);
}
else if (theirsEdit.EndA > nextOursEdit.BeginA)
{
oursEdit = nextOursEdit;
nextOursEdit = nextEdit(baseToOurs);
}
else
{
break;
}
}
// harmonize the end of the ranges in A and B
int oursEndB = oursEdit.EndB;
int theirsEndB = theirsEdit.EndB;
if (oursEdit.EndA < theirsEdit.EndA)
{
oursEndB += theirsEdit.EndA - oursEdit.EndA;
}
else
{
theirsEndB += oursEdit.EndA - theirsEdit.EndA;
}
// Add the conflict
result.add(1, oursBeginB, oursEndB,
MergeChunk.ConflictState.FIRST_CONFLICTING_RANGE);
result.add(2, theirsBeginB, theirsEndB,
MergeChunk.ConflictState.NEXT_CONFLICTING_RANGE);
current = Math.Max(oursEdit.EndA, theirsEdit.EndA);
oursEdit = nextOursEdit;
theirsEdit = nextTheirsEdit;
}
}
// maybe we have a common part behind the last edit: copy it to the
// result
if (current < @base.size())
{
result.add(0, current, @base.size(), MergeChunk.ConflictState.NO_CONFLICT);
}
return result;
}
public void assertDiff(string a, string b, string edits)
{
MyersDiff diff = new MyersDiff(toCharArray(a), toCharArray(b));
Assert.AreEqual(edits, toString(diff.getEdits()));
}