1 files changed, 202 insertions, 0 deletions
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/DocLineComparator.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/DocLineComparator.java
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+/*******************************************************************************
+ * Copyright (c) 2000, 2009 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.compare.internal;
+
+import org.eclipse.jface.text.*;
+import org.eclipse.compare.contentmergeviewer.ITokenComparator;
+import org.eclipse.compare.rangedifferencer.IRangeComparator;
+
+/**
+ * Implements the <code>IRangeComparator</code> interface for lines in a document.
+ * A <code>DocLineComparator</code> is used as the input for the <code>RangeDifferencer</code>
+ * engine to perform a line oriented compare on documents.
+ * <p>
+ * A <code>DocLineComparator</code> doesn't know anything about line separators because
+ * its notion of lines is solely defined in the underlying <code>IDocument</code>.
+ */
+public class DocLineComparator implements ITokenComparator {
+
+	private IDocument fDocument;
+	private int fLineOffset;
+	private int fLineCount;
+	private int fLength;
+	private boolean fIgnoreWhiteSpace;
+
+	/**
+	 * Creates a <code>DocLineComparator</code> for the given document range.
+	 * ignoreWhiteSpace controls whether comparing lines (in method
+	 * <code>rangesEqual<code>) should ignore whitespace.
+	 *
+	 * @param document the document from which the lines are taken
+	 * @param region if non-<code>null</code> only lines within this range are taken
+	 * @param ignoreWhiteSpace if <code>true</code> white space is ignored when comparing lines
+	 */
+	public DocLineComparator(IDocument document, IRegion region,
+			boolean ignoreWhiteSpace) {
+		fDocument = document;
+		fIgnoreWhiteSpace = ignoreWhiteSpace;
+
+		fLineOffset = 0;
+		if (region != null) {
+			fLength = region.getLength();
+			int start = region.getOffset();
+			try {
+				fLineOffset = fDocument.getLineOfOffset(start);
+			} catch (BadLocationException ex) {
+				// silently ignored
+			}
+
+			if (fLength == 0) {
+				// optimization, empty documents have one line
+				fLineCount = 1;
+			} else {
+				int endLine = fDocument.getNumberOfLines();
+				try {
+					endLine = fDocument.getLineOfOffset(start + fLength);
+				} catch (BadLocationException ex) {
+					// silently ignored
+				}
+				fLineCount = endLine - fLineOffset + 1;
+			}
+		} else {
+			fLength = document.getLength();
+			fLineCount = fDocument.getNumberOfLines();
+		}
+	}
+
+	/**
+	 * Returns the number of lines in the document.
+	 *
+	 * @return number of lines
+	 */
+	public int getRangeCount() {
+		return fLineCount;
+	}
+
+	/* (non Javadoc)
+	 * see ITokenComparator.getTokenStart
+	 */
+	public int getTokenStart(int line) {
+		try {
+			IRegion r= fDocument.getLineInformation(fLineOffset + line);
+			return r.getOffset();
+		} catch (BadLocationException ex) {
+			return fDocument.getLength();
+		}
+	}
+
+	/* (non Javadoc)
+	 * Returns the length of the given line.
+	 * see ITokenComparator.getTokenLength
+	 */
+	public int getTokenLength(int line) {
+		return getTokenStart(line+1) - getTokenStart(line);
+	}
+
+	/**
+	 * Returns <code>true</code> if a line given by the first index
+	 * matches a line specified by the other <code>IRangeComparator</code> and index.
+	 *
+	 * @param thisIndex the number of the line within this range comparator
+	 * @param otherComparator the range comparator to compare this with
+	 * @param otherIndex the number of the line within the other comparator
+	 * @return <code>true</code> if the lines are equal
+	 */
+	public boolean rangesEqual(int thisIndex, IRangeComparator otherComparator, int otherIndex) {
+
+		if (otherComparator != null && otherComparator.getClass() == getClass()) {
+			DocLineComparator other= (DocLineComparator) otherComparator;
+
+			if (fIgnoreWhiteSpace) {
+				String s1= extract(thisIndex);
+				String s2= other.extract(otherIndex);
+				//return s1.trim().equals(s2.trim());
+				return compare(s1, s2);
+			}
+
+			int tlen= getTokenLength(thisIndex);
+			int olen= other.getTokenLength(otherIndex);
+			if (tlen == olen) {
+				String s1= extract(thisIndex);
+				String s2= other.extract(otherIndex);
+				return s1.equals(s2);
+			}
+		}
+		return false;
+	}
+
+	/**
+	 * Aborts the comparison if the number of tokens is too large.
+	 * 
+	 * @param length a number on which to base the decision whether to return
+	 * 	<code>true</code> or <code>false</code>
+	 * @param maxLength another number on which to base the decision whether to return
+	 *	<code>true</code> or <code>false</code>
+	 * @param other the other <code>IRangeComparator</code> to compare with
+	 * @return <code>true</code> to avoid a too lengthy range comparison
+	 */
+	public boolean skipRangeComparison(int length, int maxLength, IRangeComparator other) {
+		return false;
+	}
+		
+	//---- private methods
+	
+	/**
+	 * Extract a single line from the underlying document without the line separator.
+	 *
+	 * @param line the number of the line to extract
+	 * @return the contents of the line as a String
+	 */
+	private String extract(int line) {
+		if (line < fLineCount) {
+			try {
+				IRegion r= fDocument.getLineInformation(fLineOffset + line);
+				return fDocument.get(r.getOffset(), r.getLength());
+			} catch(BadLocationException e) {
+				// silently ignored
+			}
+		}
+		return ""; //$NON-NLS-1$
+	}
+	
+	private boolean compare(String s1, String s2) {
+		int l1= s1.length();
+		int l2= s2.length();
+		int c1= 0, c2= 0;
+		int i1= 0, i2= 0;
+		
+		while (c1 != -1) {
+			
+			c1= -1;
+			while (i1 < l1) {
+				char c= s1.charAt(i1++);
+				if (! Character.isWhitespace(c)) {
+					c1= c;
+					break;
+				}
+			}
+			
+			c2= -1;
+			while (i2 < l2) {
+				char c= s2.charAt(i2++);
+				if (! Character.isWhitespace(c)) {
+					c2= c;
+					break;
+				}
+			}
+				
+			if (c1 != c2)
+				return false;
+		}
+		return true;
+	}
+}
+