Java tutorial
/* * ==================================================================== * * The Apache Software License, Version 1.1 * * Copyright (c) 1999-2003 The Apache Software Foundation. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. 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For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package org.apache.commons.jrcs.diff; import java.util.ArrayList; import java.util.Arrays; import java.util.Iterator; import java.util.List; /** * Holds a information about a parrt of the text involved in a differencing or * patching operation. * * @version $Id$ * @author <a href="mailto:juanco@suigeneris.org">Juanco Anez</a> * @see Diff * @see Delta */ public class Chunk extends org.apache.commons.jrcs.util.ToString { protected int anchor; protected int count; protected List chunk; /** * Creates a chunk that doesn't copy the original text. * * @param pos * the start position in the text. * @param count * the size of the chunk. */ public Chunk(int pos, int count) { this.anchor = pos; this.count = (count >= 0 ? count : 0); } /** * Creates a chunk and saves a copy the original chunk's text. * * @param iseq * the original text. * @param pos * the start position in the text. * @param count * the size of the chunk. */ public Chunk(Object[] iseq, int pos, int count) { this(pos, count); chunk = slice(iseq, pos, count); } /** * Creates a chunk that will be displaced in the resulting text, and saves a * copy the original chunk's text. * * @param iseq * the original text. * @param pos * the start position in the text. * @param count * the size of the chunk. * @param offset * the position the chunk should have in the resulting text. */ public Chunk(Object[] iseq, int pos, int count, int offset) { this(offset, count); chunk = slice(iseq, pos, count); } /** * Creates a chunk and saves a copy the original chunk's text. * * @param iseq * the original text. * @param pos * the start position in the text. * @param count * the size of the chunk. */ public Chunk(List iseq, int pos, int count) { this(pos, count); chunk = slice(iseq, pos, count); } /** * Creates a chunk that will be displaced in the resulting text, and saves a * copy the original chunk's text. * * @param iseq * the original text. * @param pos * the start position in the text. * @param count * the size of the chunk. * @param offset * the position the chunk should have in the resulting text. */ public Chunk(List iseq, int pos, int count, int offset) { this(offset, count); chunk = slice(iseq, pos, count); } /** * Returns the anchor position of the chunk. * * @return the anchor position. */ public int anchor() { return anchor; } /** * Returns the size of the chunk. * * @return the size. */ public int size() { return count; } /** * Returns the index of the first line of the chunk. */ public int first() { return anchor(); } /** * Returns the index of the last line of the chunk. */ public int last() { return anchor() + size() - 1; } /** * Returns the <i>from</i> index of the chunk in RCS terms. */ public int rcsfrom() { return anchor + 1; } /** * Returns the <i>to</i> index of the chunk in RCS terms. */ public int rcsto() { return anchor + count; } /** * Returns the text saved for this chunk. * * @return the text. */ public List chunk() { return chunk; } /** * Verifies that this chunk's saved text matches the corresponding text in * the given sequence. * * @param target * the sequence to verify against. * @return true if the texts match. */ public boolean verify(List target) { if (chunk == null) { return true; } if (last() > target.size()) { return false; } for (int i = 0; i < count; i++) { if (!target.get(anchor + i).equals(chunk.get(i))) { return false; } } return true; } /** * Delete this chunk from he given text. * * @param target * the text to delete from. */ public void applyDelete(List target) { for (int i = last(); i >= first(); i--) { target.remove(i); } } /** * Add the text of this chunk to the target at the given position. * * @param start * where to add the text. * @param target * the text to add to. */ public void applyAdd(int start, List target) { Iterator i = chunk.iterator(); while (i.hasNext()) { target.add(start++, i.next()); } } /** * Provide a string image of the chunk using the an empty prefix and * postfix. */ public void toString(StringBuffer s) { toString(s, "", ""); } /** * Provide a string image of the chunk using the given prefix and postfix. * * @param s * where the string image should be appended. * @param prefix * the text thatshould prefix each line. * @param postfix * the text that should end each line. */ public StringBuffer toString(StringBuffer s, String prefix, String postfix) { if (chunk != null) { Iterator i = chunk.iterator(); while (i.hasNext()) { s.append(prefix); s.append(i.next()); s.append(postfix); } } return s; } /** * Retreives the specified part from a {@link List List}. * * @param seq * the list to retreive a slice from. * @param pos * the start position. * @param count * the number of items in the slice. * @return a {@link List List} containing the specified items. */ public static List slice(List seq, int pos, int count) { if (count <= 0) { return new ArrayList(seq.subList(pos, pos)); } else { return new ArrayList(seq.subList(pos, pos + count)); } } /** * Retrieves a slice from an {@link Object Object} array. * * @param seq * the list to retreive a slice from. * @param pos * the start position. * @param count * the number of items in the slice. * @return a {@link List List} containing the specified items. */ public static List slice(Object[] seq, int pos, int count) { return slice(Arrays.asList(seq), pos, count); } /** * Provide a string representation of the numeric range of this chunk. */ public String rangeString() { StringBuffer result = new StringBuffer(); rangeString(result); return result.toString(); } /** * Provide a string representation of the numeric range of this chunk. * * @param s * where the string representation should be appended. */ public void rangeString(StringBuffer s) { rangeString(s, ","); } /** * Provide a string representation of the numeric range of this chunk. * * @param s * where the string representation should be appended. * @param separ * what to use as line separator. */ public void rangeString(StringBuffer s, String separ) { if (size() <= 1) { s.append(Integer.toString(rcsfrom())); } else { s.append(Integer.toString(rcsfrom())); s.append(separ); s.append(Integer.toString(rcsto())); } } }