--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/internal/NewlineFilter.java	Wed Feb 02 21:19:02 2011 +0100
@@ -0,0 +1,188 @@
+/*
+ * Copyright (c) 2011 TMate Software Ltd
+ *  
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * For information on how to redistribute this software under
+ * the terms of a license other than GNU General Public License
+ * contact TMate Software at support@svnkit.com
+ */
+package org.tmatesoft.hg.internal;
+
+import static org.tmatesoft.hg.internal.Filter.Direction.FromRepo;
+import static org.tmatesoft.hg.internal.Filter.Direction.ToRepo;
+import static org.tmatesoft.hg.internal.KeywordFilter.copySlice;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.nio.ByteBuffer;
+
+import org.tmatesoft.hg.core.Path;
+import org.tmatesoft.hg.repo.HgRepository;
+
+/**
+ *
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+public class NewlineFilter implements Filter {
+
+	// if allowInconsistent is true, filter simply pass incorrect newline characters (single \r or \r\n on *nix and single \n on Windows) as is,
+	// i.e. doesn't try to convert them into appropriate newline characters. XXX revisit if Keyword extension behaves differently
+	private final boolean allowInconsistent;
+	private final boolean winToNix;
+
+	private NewlineFilter(boolean failIfInconsistent, int transform) {
+		winToNix = transform == 0;
+		allowInconsistent = !failIfInconsistent;
+	}
+
+	public ByteBuffer filter(ByteBuffer src) {
+		if (winToNix) {
+			return win2nix(src);
+		} else {
+			return nix2win(src);
+		}
+	}
+
+	private ByteBuffer win2nix(ByteBuffer src) {
+		int x = src.position(); // source index
+		int lookupStart = x;
+		ByteBuffer dst = null;
+		while (x < src.limit()) {
+			// x, lookupStart, ir and in are absolute positions within src buffer, which is never read with modifying operations
+			int ir = indexOf('\r', src, lookupStart);
+			int in = indexOf('\n', src, lookupStart);
+			if (ir == -1) {
+				if (in == -1 || allowInconsistent) {
+					if (dst != null) {
+						copySlice(src, x, src.limit(), dst);
+						x = src.limit(); // consumed all
+					}
+					break;
+				} else {
+					fail(src, in);
+				}
+			}
+			// in == -1 while ir != -1 may be valid case if ir is the last char of the buffer, we check below for that
+			if (in != -1 && in != ir+1 && !allowInconsistent) {
+				fail(src, in);
+			}
+			if (dst == null) {
+				dst = ByteBuffer.allocate(src.remaining());
+			}
+			copySlice(src, x, ir, dst);
+			if (ir+1 == src.limit()) {
+				// last char of the buffer - 
+				// consume src till that char and let next iteration work on it
+				x = ir;
+				break;
+			}
+			if (in != ir + 1) {
+				x = ir+1; // generally in, but if allowInconsistent==true and \r is not followed by \n, then 
+				// cases like "one \r two \r\n three" shall be processed correctly (second pair would be ignored if x==in)
+				lookupStart = ir+1;
+			} else {
+				x = in;
+				lookupStart = x+1; // skip \n for next lookup
+			}
+		}
+		src.position(x); // mark we've consumed up to x
+		return dst == null ? src : (ByteBuffer) dst.flip();
+	}
+
+	private ByteBuffer nix2win(ByteBuffer src) {
+		int x = src.position();
+		ByteBuffer dst = null;
+		while (x < src.limit()) {
+			int in = indexOf('\n', src, x);
+			int ir = indexOf('\r', src, x, in == -1 ? src.limit() : in);
+			if (in == -1) {
+				if (ir == -1 || allowInconsistent) {
+					break;
+				} else {
+					fail(src, ir);
+				}
+			} else if (ir != -1 && !allowInconsistent) {
+				fail(src, ir);
+			}
+			
+			// x <= in < src.limit
+			// allowInconsistent && x <= ir < in   || ir == -1  
+			if (dst == null) {
+				// buffer full of \n grows as much as twice in size
+				dst = ByteBuffer.allocate(src.remaining() * 2);
+			}
+			copySlice(src, x, in, dst);
+			if (ir == -1 || ir+1 != in) {
+				dst.put((byte) '\r');
+			} // otherwise (ir!=-1 && ir+1==in) we found \r\n pair, don't convert to \r\r\n
+			// we may copy \n at src[in] on the next iteration, but would need extra lookupIndex variable then.
+			dst.put((byte) '\n');
+			x = in+1;
+		}
+		src.position(x);
+		return dst == null ? src : (ByteBuffer) dst.flip();
+	}
+
+
+	private void fail(ByteBuffer b, int pos) {
+		throw new RuntimeException(String.format("Inconsistent newline characters in the stream (char 0x%x, local index:%d)", b.get(pos), pos));
+	}
+
+	private static int indexOf(char ch, ByteBuffer b, int from) {
+		return indexOf(ch, b, from, b.limit());
+	}
+
+	// looks up in buf[from..to)
+	private static int indexOf(char ch, ByteBuffer b, int from, int to) {
+		for (int i = from; i < to; i++) {
+			byte c = b.get(i);
+			if (ch == c) {
+				return i;
+			}
+		}
+		return -1;
+	}
+
+	public static class Factory implements Filter.Factory {
+		private final boolean localIsWin = File.separatorChar == '\\'; // FIXME
+		private final boolean failIfInconsistent = true;
+
+		public Filter create(HgRepository hgRepo, Path path, Options opts) {
+			if (opts.getDirection() == FromRepo) {
+			} else if (opts.getDirection() == ToRepo) {
+			}
+			return new NewlineFilter(failIfInconsistent, 1);
+		}
+	}
+
+	public static void main(String[] args) throws Exception {
+		FileInputStream fis = new FileInputStream(new File("/temp/design.lf.txt"));
+		FileOutputStream fos = new FileOutputStream(new File("/temp/design.newline.out"));
+		ByteBuffer b = ByteBuffer.allocate(12);
+		NewlineFilter nlFilter = new NewlineFilter(true, 1);
+		while (fis.getChannel().read(b) != -1) {
+			b.flip(); // get ready to be read
+			ByteBuffer f = nlFilter.filter(b);
+			fos.getChannel().write(f); // XXX in fact, f may not be fully consumed
+			if (b.hasRemaining()) {
+				b.compact();
+			} else {
+				b.clear();
+			}
+		}
+		fis.close();
+		fos.flush();
+		fos.close();
+	}
+
+}