### Eclipse Workspace Patch 1.0
#P org.eclipse.compare.tests
Index: src/org/eclipse/compare/tests/DocLineComparatorTest.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.compare.tests/src/org/eclipse/compare/tests/DocLineComparatorTest.java,v
retrieving revision 1.5
diff -u -r1.5 DocLineComparatorTest.java
--- src/org/eclipse/compare/tests/DocLineComparatorTest.java	26 Jan 2009 09:44:27 -0000	1.5
+++ src/org/eclipse/compare/tests/DocLineComparatorTest.java	1 Apr 2009 14:54:01 -0000
@@ -80,7 +80,7 @@
 
 		Assert.assertTrue(comp1.rangesEqual(0, comp2, 0));
 		Assert.assertEquals(comp1.getRangeCount(), comp2.getRangeCount());
-		Assert.assertEquals(0, comp2.getRangeCount());
+		Assert.assertEquals(1, comp2.getRangeCount());
 	}
 	
 	public void testOneLine() {
#P org.eclipse.compare
Index: compare/org/eclipse/compare/internal/DocLineComparator.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.compare/plugins/org.eclipse.compare/compare/org/eclipse/compare/internal/DocLineComparator.java,v
retrieving revision 1.20
diff -u -r1.20 DocLineComparator.java
--- compare/org/eclipse/compare/internal/DocLineComparator.java	26 Jan 2009 09:44:25 -0000	1.20
+++ compare/org/eclipse/compare/internal/DocLineComparator.java	1 Apr 2009 14:54:03 -0000
@@ -39,33 +39,36 @@
 	 * @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) {
-			region = new Region(0, fDocument.getLength());
-		}
-		fLength= region.getLength();
-		int start= region.getOffset();
-		try {
-			fLineOffset= fDocument.getLineOfOffset(start);
-		} catch (BadLocationException ex) {
-			// silently ignored
-		}
-
-		if (fLength == 0)
-			fLineCount= 0;
-		else {
-			int endLine= fDocument.getNumberOfLines();
+	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 {
-				endLine= fDocument.getLineOfOffset(start + fLength);
+				fLineOffset = fDocument.getLineOfOffset(start);
 			} catch (BadLocationException ex) {
 				// silently ignored
 			}
-			fLineCount= endLine - fLineOffset + 1;
+
+			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();
 		}
 	}