--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/NGSrich_0.5.5/src/datastructures/Frame.java	Mon Nov 21 08:12:19 2011 -0500
@@ -0,0 +1,94 @@
+package datastructures;
+
+/**
+ * Used for various purposes.
+ * 
+ * @author Ali Abdallah
+ * @version 01.2011
+ * @since jdk 1.6.0
+ */
+public class Frame {
+	
+	// Self explanatory.
+	protected int start; 
+	protected int end;
+	protected int length;
+	
+	/**
+	 * Constructs a frame with start position "start", length "length" and
+	 * end position "start+length-1".
+	 * @param start the start position of the frame.
+	 * @param length the length of the frame.
+	 */
+	public Frame(int start, int length) {
+		this.start = start; end = start+length-1;
+		this.length = length;
+	}
+	
+	/**
+	 * Verify if this frame overlaps the frame specified in the parameter.
+	 * @param f the frame which potentially overlaps the calling frame.
+	 * @return true if the two frames overlap each other and false otherwise.
+	 */
+	public boolean overlaps(Frame f){
+		return (end >= f.start() && start < f.end());
+	}
+	
+	/**
+	 * Computes the size of the overlap area.
+	 * @param f the frame overlapping the calling frame.
+	 * @return the size of the overlap if an overlap exists and -1 otherwise.
+	 */
+	public int overlapSize(Frame f){
+		if(this.overlaps(f)){
+			int s = Math.max(start, f.start());
+			int e = Math.min(end, f.end());
+			return e-s+1;
+		}
+		return -1;
+	}
+	
+	/**
+	 * Unify the calling frame with the frame specified in the parameter.
+	 * @param f the frame to be unified with the calling frame.
+	 * @return the union of the calling frame and f.
+	 */
+	public Frame unify(Frame f){
+		return 
+			new Frame(Math.min(this.start, f.start), 
+					  Math.max(this.end,f.end)-Math.min(this.start, f.start)+1);	
+	}
+
+	/**
+	 * self explanatory
+	 * @return start of the frame.
+	 */
+	public int start(){
+		return start;
+	}
+	
+	/**
+	 * self explanatory
+	 * @return end of the frame.
+	 */
+	public int end(){
+		return end;
+	}
+	
+	/**
+	 * self explanatory
+	 * @return length of the frame.
+	 */
+	public int length(){
+		return length;
+	}
+	
+	/**
+	 * Make a string representation of the frame.
+	 * @return a string representation of the string.
+	 */
+	public String toString(){
+		return start+":"+end;
+	}
+
+}