private boolean processMerge()

in org.eclipse.jgit/src/org/eclipse/jgit/blame/BlameGenerator.java [772:928]
114 lines of code
35 McCabe index (conditional complexity)

	private boolean processMerge(Candidate n) throws IOException {
		int pCnt = n.getParentCount();

		// If any single parent exactly matches the merge, follow only
		// that one parent through history.
		ObjectId[] ids = null;
		for (int pIdx = 0; pIdx < pCnt; pIdx++) {
			RevCommit parent = n.getParent(pIdx);
			revPool.parseHeaders(parent);
			if (!find(parent, n.sourcePath))
				continue;
			if (!(n instanceof ReverseCandidate) && idBuf.equals(n.sourceBlob))
				return blameEntireRegionOnParent(n, parent);
			if (ids == null)
				ids = new ObjectId[pCnt];
			ids[pIdx] = idBuf.toObjectId();
		}

		// If rename detection is enabled, search for any relevant names.
		DiffEntry[] renames = null;
		if (renameDetector != null) {
			renames = new DiffEntry[pCnt];
			for (int pIdx = 0; pIdx < pCnt; pIdx++) {
				RevCommit parent = n.getParent(pIdx);
				if (ids != null && ids[pIdx] != null)
					continue;

				DiffEntry r = findRename(parent, n.sourceCommit, n.sourcePath);
				if (r == null)
					continue;

				if (n instanceof ReverseCandidate) {
					if (ids == null)
						ids = new ObjectId[pCnt];
					ids[pCnt] = r.getOldId().toObjectId();
				} else if (0 == r.getOldId().prefixCompare(n.sourceBlob)) {
					// A 100% rename without any content change can also
					// skip directly to the parent. Note this bypasses an
					// earlier parent that had the path (above) but did not
					// have an exact content match. For performance reasons
					// we choose to follow the one parent over trying to do
					// possibly both parents.
					n.sourcePath = PathFilter.create(r.getOldPath());
					return blameEntireRegionOnParent(n, parent);
				}

				renames[pIdx] = r;
			}
		}

		// Construct the candidate for each parent.
		Candidate[] parents = new Candidate[pCnt];
		for (int pIdx = 0; pIdx < pCnt; pIdx++) {
			RevCommit parent = n.getParent(pIdx);

			Candidate p;
			if (renames != null && renames[pIdx] != null) {
				p = n.create(getRepository(), parent,
						PathFilter.create(renames[pIdx].getOldPath()));
				p.renameScore = renames[pIdx].getScore();
				p.sourceBlob = renames[pIdx].getOldId().toObjectId();
			} else if (ids != null && ids[pIdx] != null) {
				p = n.create(getRepository(), parent, n.sourcePath);
				p.sourceBlob = ids[pIdx];
			} else {
				continue;
			}

			EditList editList;
			if (n instanceof ReverseCandidate
					&& p.sourceBlob.equals(n.sourceBlob)) {
				// This special case happens on ReverseCandidate forks.
				p.sourceText = n.sourceText;
				editList = new EditList(0);
			} else {
				p.loadText(reader);
				editList = diffAlgorithm.diff(textComparator,
						p.sourceText, n.sourceText);
			}

			if (editList.isEmpty()) {
				// Ignoring whitespace (or some other special comparator) can
				// cause non-identical blobs to have an empty edit list. In
				// a case like this push the parent alone.
				if (n instanceof ReverseCandidate) {
					parents[pIdx] = p;
					continue;
				}

				p.regionList = n.regionList;
				n.regionList = null;
				parents[pIdx] = p;
				break;
			}

			p.takeBlame(editList, n);

			// Only remember this parent candidate if there is at least
			// one region that was blamed on the parent.
			if (p.regionList != null) {
				// Reverse blame requires inverting the regions. This puts
				// the regions the parent deleted from us into the parent,
				// and retains the common regions to look at other parents
				// for deletions.
				if (n instanceof ReverseCandidate) {
					Region r = p.regionList;
					p.regionList = n.regionList;
					n.regionList = r;
				}

				parents[pIdx] = p;
			}
		}

		if (n instanceof ReverseCandidate) {
			// On a reverse blame report all deletions found in the children,
			// and pass on to them a copy of our region list.
			Candidate resultHead = null;
			Candidate resultTail = null;

			for (int pIdx = 0; pIdx < pCnt; pIdx++) {
				Candidate p = parents[pIdx];
				if (p == null)
					continue;

				if (p.regionList != null) {
					Candidate r = p.copy(p.sourceCommit);
					if (resultTail != null) {
						resultTail.queueNext = r;
						resultTail = r;
					} else {
						resultHead = r;
						resultTail = r;
					}
				}

				if (n.regionList != null) {
					p.regionList = n.regionList.deepCopy();
					push(p);
				}
			}

			if (resultHead != null)
				return result(resultHead);
			return false;
		}

		// Push any parents that are still candidates.
		for (int pIdx = 0; pIdx < pCnt; pIdx++) {
			if (parents[pIdx] != null)
				push(parents[pIdx]);
		}

		if (n.regionList != null)
			return result(n);
		return false;
	}