--- a/Diff2.st	Thu Apr 05 18:53:51 2012 +0100
+++ b/Diff2.st	Fri Apr 06 16:56:16 2012 +0100
@@ -382,6 +382,18 @@
 extractFrom: aCollection
 	"Extracts a subcollection from aCollection corresponding to my offset and length."
 	^ aCollection copyFrom: offset to: offset + length - 1.
+!
+
+extractSafeFrom: aCollection
+    "Extracts a subcollection from aCollection corresponding to my offset and length.
+     Returns nil if extraction fails (out of bounds)"
+    ^((offset <= aCollection size) and:[(offset + length - 1) <= aCollection size]) ifTrue:[
+        aCollection copyFrom: offset to: offset + length - 1
+    ] ifFalse:[
+        nil
+    ].
+
+    "Created: / 06-04-2012 / 12:37:28 / Jan Vrany <jan.vrany@fit.cvut.cz>"
 ! !
 
 !Diff2::Chunk methodsFor:'comparing'!
@@ -814,5 +826,5 @@
 !Diff2 class methodsFor:'documentation'!
 
 version_SVN
-    ^ '$Id: Diff2.st 7936 2012-03-16 22:44:50Z vranyj1 $'
+    ^ '$Id: Diff2.st 7973 2012-04-06 15:56:16Z vranyj1 $'
 ! !