Mercurial > hg4j
view src/org/tmatesoft/hg/internal/KeywordFilter.java @ 112:d488c7638b87
Prototype Filter support with keyword filter as a playground
author | Artem Tikhomirov <tikhomirov.artem@gmail.com> |
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date | Tue, 01 Feb 2011 00:21:08 +0100 |
parents | |
children | 67ae317408c9 |
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/* * 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 java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.nio.ByteBuffer; import java.util.TreeMap; import org.tmatesoft.hg.core.Path; import org.tmatesoft.hg.repo.HgRepository; /** * * @author Artem Tikhomirov * @author TMate Software Ltd. */ public class KeywordFilter implements Filter { private final boolean isExpanding; private final TreeMap<String,String> keywords; private final int minBufferLen; /** * * @param expand <code>true</code> to expand keywords, <code>false</code> to shrink */ private KeywordFilter(boolean expand) { isExpanding = expand; keywords = new TreeMap<String,String>(); keywords.put("Id", "Id"); keywords.put("Revision", "Revision"); keywords.put("Author", "Author"); int l = 0; for (String s : keywords.keySet()) { if (s.length() > l) { l = s.length(); } } // FIXME later may implement #filter() not to read full kw value (just "$kw:"). However, limit of maxLen + 2 would keep valid. // for buffers less then minBufferLen, there are chances #filter() implementation would never end // (i.e. for input "$LongestKey"$ minBufferLen = l + 2 + (isExpanding ? 0 : 120 /*any reasonable constant for max possible kw value length*/); } /** * @param src buffer ready to be read * @return buffer ready to be read and original buffer's position modified to reflect consumed bytes. IOW, if source buffer * on return has remaining bytes, they are assumed not-read (not processed) and next chunk passed to filter is supposed to * start with them */ public ByteBuffer filter(ByteBuffer src) { if (src.capacity() < minBufferLen) { throw new IllegalStateException(String.format("Need buffer of at least %d bytes to ensure filter won't hang", minBufferLen)); } ByteBuffer rv = null; int keywordStart = -1; int x = src.position(); while (x < src.limit()) { if (keywordStart == -1) { int i = indexOf(src, '$', x, false); if (i == -1) { if (rv == null) { return src; } else { copySlice(src, x, src.limit(), rv); rv.flip(); src.position(src.limit()); return rv; } } keywordStart = i; // fall-through } if (keywordStart >= 0) { int i = indexOf(src, '$', keywordStart+1, true); if (i == -1) { // end of buffer reached if (rv == null) { if (keywordStart == x) { // FIXME in fact, x might be equal to keywordStart and to src.position() here ('$' is first character in the buffer, // and there are no other '$' not eols till the end of the buffer). This would lead to deadlock (filter won't consume any // bytes). To prevent this, either shall copy bytes [keywordStart..buffer.limit()) to local buffer and use it on the next invocation, // or add lookup of the keywords right after first '$' is found (do not wait for closing '$'). For now, large enough src buffer would be sufficient // not to run into such situation throw new IllegalStateException("Try src buffer of a greater size"); } rv = ByteBuffer.allocateDirect(keywordStart - x); } // copy all from source till latest possible kw start copySlice(src, x, keywordStart, rv); rv.flip(); // and tell caller we've consumed only to the potential kw start src.position(keywordStart); return rv; } else if (src.get(i) == '$') { // end of keyword, or start of a new one. String keyword; if ((keyword = matchKeyword(src, keywordStart, i)) != null) { if (rv == null) { rv = ByteBuffer.allocateDirect(isExpanding ? src.capacity() * 4 : src.capacity()); } copySlice(src, x, keywordStart+1, rv); rv.put(keyword.getBytes()); if (isExpanding) { rv.put((byte) ':'); rv.put((byte) ' '); expandKeywordValue(keyword, rv); rv.put((byte) ' '); } rv.put((byte) '$'); keywordStart = -1; x = i+1; continue; } else { if (rv != null) { // we've already did some substitution, thus need to copy bytes we've scanned. copySlice(src, x, i, rv); } // no else in attempt to avoid rv creation if no real kw would be found keywordStart = i; x = i; // '$' at i wasn't consumed, hence x points to i, not i+1. This is to avoid problems with case: "sdfsd $ asdfs $Id$ sdf" continue; } } else { assert src.get(i) == '\n' || src.get(i) == '\r'; // line break if (rv != null) { copySlice(src, x, i+1, rv); } x = i+1; keywordStart = -1; // Wasn't keyword, really continue; // try once again } } } if (keywordStart != -1) { if (rv == null) { // no expansion happened yet, and we have potential kw start rv = ByteBuffer.allocateDirect(keywordStart - src.position()); copySlice(src, src.position(), keywordStart, rv); } src.position(keywordStart); } if (rv != null) { rv.flip(); return rv; } return src; } /** * @param keyword * @param rv */ private void expandKeywordValue(String keyword, ByteBuffer rv) { if ("Id".equals(keyword)) { rv.put(identityString().getBytes()); } else if ("Revision".equals(keyword)) { rv.put(revision()); } else if ("Author".equals(keyword)) { rv.put(username().getBytes()); } } private String matchKeyword(ByteBuffer src, int kwStart, int kwEnd) { assert kwEnd - kwStart - 1 > 0; assert src.get(kwStart) == src.get(kwEnd) && src.get(kwEnd) == '$'; char[] chars = new char[kwEnd - kwStart - 1]; int i; for (i = 0; i < chars.length; i++) { char c = (char) src.get(kwStart + 1 + i); if (c == ':') { break; } chars[i] = c; } String kw = new String(chars, 0, i); return keywords.get(kw); } // copies part of the src buffer, [from..to). doesn't modify src position private static void copySlice(ByteBuffer src, int from, int to, ByteBuffer dst) { if (to > src.limit()) { throw new IllegalArgumentException("Bad right boundary"); } if (dst.remaining() < to - from) { throw new IllegalArgumentException("Not enough room in the destination buffer"); } for (int i = from; i < to; i++) { dst.put(src.get(i)); } } private static int indexOf(ByteBuffer b, char ch, int from, boolean newlineBreaks) { for (int i = from; i < b.limit(); i++) { byte c = b.get(i); if (ch == c) { return i; } if (newlineBreaks && (c == '\n' || c == '\r')) { return i; } } return -1; } private String identityString() { return "sample/file.txt, asd"; } private byte[] revision() { return "1234567890ab".getBytes(); } private String username() { /* ui.py: username() Searched in this order: $HGUSER, [ui] section of hgrcs, $EMAIL and stop searching if one of these is set. If not found and ui.askusername is True, ask the user, else use ($LOGNAME or $USER or $LNAME or $USERNAME) + "@full.hostname". */ return "<Sample> sample@sample.org"; } public static class Factory implements Filter.Factory { public Filter create(HgRepository hgRepo, Path path) { return new KeywordFilter(true); } } public static void main(String[] args) throws Exception { FileInputStream fis = new FileInputStream(new File("/temp/kwoutput.txt")); FileOutputStream fos = new FileOutputStream(new File("/temp/kwoutput2.txt")); ByteBuffer b = ByteBuffer.allocateDirect(256); KeywordFilter kwFilter = new KeywordFilter(false); while (fis.getChannel().read(b) != -1) { b.flip(); // get ready to be read ByteBuffer f = kwFilter.filter(b); fos.getChannel().write(f); if (b.hasRemaining()) { ByteBuffer remaining = b.slice(); b.clear(); b.put(remaining); } else { b.clear(); } } fis.close(); fos.flush(); fos.close(); } }