Improve the child record adding code

git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@386996 13f79535-47bb-0310-9956-ffa450edef68

src/scratchpad/src/org/apache/poi/hslf/record/RecordContainer.java

@@ -35,6 +35,7 @@ import java.io.ByteArrayOutputStream;
 public abstract class RecordContainer extends Record
 {
 	protected Record[] _children;
+	private Boolean addingChildRecordLock = new Boolean(true);
 	
 	/** 
 	 * Return any children 
@@ -51,40 +52,101 @@ public abstract class RecordContainer extends Record
 	 *  return the new list.
 	 */
 	public Record[] appendChildRecord(Record newChild, Record[] children) {
-		Record[] r = new Record[children.length + 1];
-		System.arraycopy(children,0,r,0,children.length);
-		r[r.length-1] = newChild;
+		Record[] r;
+		synchronized(addingChildRecordLock) {
+			r = new Record[children.length + 1];
+			System.arraycopy(children,0,r,0,children.length);
+			r[r.length-1] = newChild;
+		}
 		return r;
 	}
 	
+	/**
+	 * Finds the location of the given child record
+	 */
+	private int findChildLocation(Record child) {
+		// Synchronized as we don't want things changing 
+		//  as we're doing our search
+		synchronized(addingChildRecordLock) {
+			for(int i=0; i<_children.length; i++) {
+				if(_children[i].equals(child)) {
+					return i;
+				}
+			}
+		}	
+		return -1;
+	}
+	
+	/**
+	 * Adds the given new Child Record at the given location,
+	 *  shuffling everything from there on down by one
+	 * @param newChild
+	 * @param position
+	 */
+	private void addChildAt(Record newChild, int position) {
+		synchronized(addingChildRecordLock) {
+			Record[] newChildren = new Record[_children.length+1];
+			// Move over to the new array, shuffling on by one after
+			//  the addition point
+			for(int i=0; i<_children.length; i++) {
+				if(i == position) {
+					newChildren[i] = newChild;
+				}
+
+				if(i >= position) {
+					newChildren[i+1] = _children[i];
+				}
+				if(i < position) {
+					newChildren[i] = _children[i];
+				}
+			}
+			
+			// Special case - new record goes at the end
+			if(position == _children.length) {
+				newChildren[position] = newChild;
+			}
+			
+			// All done, replace our child list
+			_children = newChildren;
+		}
+	}
+	
 	/**
 	 * Adds the given Child Record after the supplied record
 	 * @param newChild
 	 * @param after
 	 */
-	public synchronized void addChildAfter(Record newChild, Record after) {
-		boolean added = false;
-		Record[] newChildren = new Record[_children.length+1];
-		for(int i=0; i<_children.length; i++) {
-			int newPos = i;
-			if(added) { newPos++; }
-			
-			newChildren[newPos] = _children[i];
-			if(_children[i].equals(after)) {
-				// Found one to add after
-				added = true;
-				newPos++;
-				newChildren[newPos] = newChild;
+	public void addChildAfter(Record newChild, Record after) {
+		synchronized(addingChildRecordLock) {
+			// Decide where we're going to put it
+			int loc = findChildLocation(after);
+			if(loc == -1) {
+				throw new IllegalArgumentException("Asked to add a new child after another record, but that record wasn't one of our children!");
 			}
-		}
-		
-		if(added) {
-			_children = newChildren;
-		} else {
-			throw new IllegalArgumentException("Asked to add a new child after another record, but that record wasn't one of our children!");
+				
+			// Add one place after the supplied record
+			addChildAt(newChild, loc+1);
 		}
 	}
-
+	
+	/**
+	 * Adds the given Child Record before the supplied record
+	 * @param newChild
+	 * @param after
+	 */
+	public void addChildBefore(Record newChild, Record before) {
+		synchronized(addingChildRecordLock) {
+			// Decide where we're going to put it
+			int loc = findChildLocation(before);
+			if(loc == -1) {
+				throw new IllegalArgumentException("Asked to add a new child before another record, but that record wasn't one of our children!");
+			}
+				
+			// Add at the place of the supplied record
+			addChildAt(newChild, loc);
+		}
+	}
+	
 	/**
 	 * Write out our header, and our children.
 	 * @param headerA the first byte of the header