private void applyText()

in org.eclipse.jgit/src/org/eclipse/jgit/api/ApplyCommand.java [546:701]
138 lines of code
32 McCabe index (conditional complexity)

	private void applyText(Repository repository, String path, RawText rt,
			File f, FileHeader fh, CheckoutMetadata checkOut)
			throws IOException, PatchApplyException {
		List<ByteBuffer> oldLines = new ArrayList<>(rt.size());
		for (int i = 0; i < rt.size(); i++) {
			oldLines.add(rt.getRawString(i));
		}
		List<ByteBuffer> newLines = new ArrayList<>(oldLines);
		int afterLastHunk = 0;
		int lineNumberShift = 0;
		int lastHunkNewLine = -1;
		for (HunkHeader hh : fh.getHunks()) {

			// We assume hunks to be ordered
			if (hh.getNewStartLine() <= lastHunkNewLine) {
				throw new PatchApplyException(MessageFormat
						.format(JGitText.get().patchApplyException, hh));
			}
			lastHunkNewLine = hh.getNewStartLine();

			byte[] b = new byte[hh.getEndOffset() - hh.getStartOffset()];
			System.arraycopy(hh.getBuffer(), hh.getStartOffset(), b, 0,
					b.length);
			RawText hrt = new RawText(b);

			List<ByteBuffer> hunkLines = new ArrayList<>(hrt.size());
			for (int i = 0; i < hrt.size(); i++) {
				hunkLines.add(hrt.getRawString(i));
			}

			if (hh.getNewStartLine() == 0) {
				// Must be the single hunk for clearing all content
				if (fh.getHunks().size() == 1
						&& canApplyAt(hunkLines, newLines, 0)) {
					newLines.clear();
					break;
				}
				throw new PatchApplyException(MessageFormat
						.format(JGitText.get().patchApplyException, hh));
			}
			// Hunk lines as reported by the hunk may be off, so don't rely on
			// them.
			int applyAt = hh.getNewStartLine() - 1 + lineNumberShift;
			// But they definitely should not go backwards.
			if (applyAt < afterLastHunk && lineNumberShift < 0) {
				applyAt = hh.getNewStartLine() - 1;
				lineNumberShift = 0;
			}
			if (applyAt < afterLastHunk) {
				throw new PatchApplyException(MessageFormat
						.format(JGitText.get().patchApplyException, hh));
			}
			boolean applies = false;
			int oldLinesInHunk = hh.getLinesContext()
					+ hh.getOldImage().getLinesDeleted();
			if (oldLinesInHunk <= 1) {
				// Don't shift hunks without context lines. Just try the
				// position corrected by the current lineNumberShift, and if
				// that fails, the position recorded in the hunk header.
				applies = canApplyAt(hunkLines, newLines, applyAt);
				if (!applies && lineNumberShift != 0) {
					applyAt = hh.getNewStartLine() - 1;
					applies = applyAt >= afterLastHunk
							&& canApplyAt(hunkLines, newLines, applyAt);
				}
			} else {
				int maxShift = applyAt - afterLastHunk;
				for (int shift = 0; shift <= maxShift; shift++) {
					if (canApplyAt(hunkLines, newLines, applyAt - shift)) {
						applies = true;
						applyAt -= shift;
						break;
					}
				}
				if (!applies) {
					// Try shifting the hunk downwards
					applyAt = hh.getNewStartLine() - 1 + lineNumberShift;
					maxShift = newLines.size() - applyAt - oldLinesInHunk;
					for (int shift = 1; shift <= maxShift; shift++) {
						if (canApplyAt(hunkLines, newLines, applyAt + shift)) {
							applies = true;
							applyAt += shift;
							break;
						}
					}
				}
			}
			if (!applies) {
				throw new PatchApplyException(MessageFormat
						.format(JGitText.get().patchApplyException, hh));
			}
			// Hunk applies at applyAt. Apply it, and update afterLastHunk and
			// lineNumberShift
			lineNumberShift = applyAt - hh.getNewStartLine() + 1;
			int sz = hunkLines.size();
			for (int j = 1; j < sz; j++) {
				ByteBuffer hunkLine = hunkLines.get(j);
				if (!hunkLine.hasRemaining()) {
					// Completely empty line; accept as empty context line
					applyAt++;
					continue;
				}
				switch (hunkLine.array()[hunkLine.position()]) {
				case ' ':
					applyAt++;
					break;
				case '-':
					newLines.remove(applyAt);
					break;
				case '+':
					newLines.add(applyAt++, slice(hunkLine, 1));
					break;
				default:
					break;
				}
			}
			afterLastHunk = applyAt;
		}
		if (!isNoNewlineAtEndOfFile(fh)) {
			newLines.add(null);
		}
		if (!rt.isMissingNewlineAtEnd()) {
			oldLines.add(null);
		}
		if (oldLines.equals(newLines)) {
			return; // Unchanged; don't touch the file
		}

		TemporaryBuffer buffer = new TemporaryBuffer.LocalFile(null);
		try {
			try (OutputStream out = buffer) {
				for (Iterator<ByteBuffer> l = newLines.iterator(); l
						.hasNext();) {
					ByteBuffer line = l.next();
					if (line == null) {
						// Must be the marker for the final newline
						break;
					}
					out.write(line.array(), line.position(), line.remaining());
					if (l.hasNext()) {
						out.write('\n');
					}
				}
			}
			try (OutputStream output = new FileOutputStream(f)) {
				DirCacheCheckout.getContent(repository, path, checkOut,
						new StreamLoader(buffer::openInputStream,
								buffer.length()),
						null, output);
			}
		} finally {
			buffer.destroy();
		}
		repository.getFS().setExecute(f,
				fh.getNewMode() == FileMode.EXECUTABLE_FILE);
	}