objecttree.java

JPC: x86 PC Hardware Emulator. 牛津大学开发的一个纯JAVA的x86系统结构硬件模拟器。

                if (n == null)
                    rightUsed = false;
                inserted = true;
            }

            if (size() == 0)
                return null;
            else if (inserted)
                return this;
            
            /* nodes are full, therefore must change to different node type */

            Node replacementNode = new NarrowNode();
            SimpleByteArray dummy = new SimpleByteArray(1);
            dummy.setByte(0, leftIndex);
            replacementNode = replacementNode.setNode(leftNode, dummy, 0, 0);
            dummy.setByte(0, rightIndex);
            replacementNode = replacementNode.setNode(rightNode, dummy, 0, 0);
            replacementNode = replacementNode.setNode(n, mem, offset, maxOffset);

            return replacementNode;
        }
        
        public Node getNode(ByteArray mem, int offset)
        {
            byte index = mem.getByte(offset);

            if ((leftIndex == index) && (leftUsed))
                return leftNode;
            else if ((rightIndex == index) && (rightUsed))
                return rightNode;
            else
                return null;
        }
        
        public boolean visitNodes(ObjectTreeVisitor visitor)
        {
            if (!super.visitNodes(visitor))
                return false;

            if (rightNode != null)
            {
                if (!rightNode.visitNodes(visitor))
                    return false;
            }
            if (leftNode != null)
            {
                if (!leftNode.visitNodes(visitor))
                    return false;
            }

            return true;
        }

        public void print(String indent)
        {
            System.out.println(indent+"Binary["+leftIndex+" "+rightIndex+"]");
            if (leftNode != null)
                leftNode.print(indent+" ");
            if (rightNode != null)
                rightNode.print(indent+" ");
        }
    }

    public static class SingularNode extends Node
    {
        private Node childNode;
        private byte childIndex;
        private boolean childUsed;
       
        /** Create a new single node */
        SingularNode()
        {
            childUsed = false;
        }

        public int size()
        {
            if (childUsed)
                return 1;
            return 0;
        }

        public Node setNode(Node n, ByteArray mem, int offset, int maxOffset)
        {
            byte index = mem.getByte(offset);

            if (!childUsed || (childUsed && (childIndex == index)))
            {
                // if only child node is to be null, no point in having this node!
                if (n == null)
                    return null;

                childIndex = index;
                childNode = n;
                childUsed = true;
                return this;
            }

            /* nodes are full, therefore must change to different node type */

            Node replacementNode = new BinaryNode();
            SimpleByteArray dummy = new SimpleByteArray(1);
            dummy.setByte(0, childIndex);
            replacementNode = replacementNode.setNode(childNode, dummy, 0, 0);
            replacementNode = replacementNode.setNode(n, mem, offset, maxOffset);

            return replacementNode;
        }

        public Node getNode(ByteArray mem, int offset)
        {
            if (childIndex == mem.getByte(offset))
                return childNode;
            else
                return null;
        }
        
        public boolean visitNodes(ObjectTreeVisitor visitor)
        {
            if (!super.visitNodes(visitor))
                return false;

            if (childNode != null)
            {
                if (!childNode.visitNodes(visitor))
                    return false;
            }

            return true;
        }

        public void print(String indent)
        {
            System.out.println(indent+"SINGLE!!!!");
        }
    }

    public static class SequenceNode extends Node
    {
        byte[] sequence;
        Node child;

        public SequenceNode(Node child, ByteArray arr, int offset, int maxOffset)
        {
            this.child = child;
            sequence = new byte[maxOffset - offset + 1];
            arr.copyContentsInto(offset, sequence, 0, sequence.length);
        }

        public int size()
        {
            return 1;
        }

        public Node setNode(Node n, ByteArray mem, int offset, int maxOffset)
        {
            for (int i=0; i<sequence.length; i++)
            {
                if (mem.getByte(offset + i) == sequence[i])
                    continue;

                BinaryNode branch = new BinaryNode();
                SimpleByteArray dummy = new SimpleByteArray(sequence);

                Node left = null;
                if (i+1 == sequence.length)
                    left = child;
                else
                    left = new SequenceNode(child, dummy, i+1, sequence.length-1);
                
                Node right = null;
                if (offset+i == maxOffset)
                    right = n;
                else
                    right = new SequenceNode(n, mem, offset+i+1, maxOffset);

                branch.setNode(left, dummy, i, i);
                branch.setNode(right, mem, offset+i, offset+i);

                if (i == 0)
                    return branch;
                return new SequenceNode(branch, dummy, 0, i-1);
            }
            
            if (n == null)
                return null;
            child = n;
            return this;
        }

        public Node getNode(ByteArray mem, int offset)
        {
            for (int i=0; i<sequence.length; i++)
            {
                if (mem.getByte(offset + i) == sequence[i])
                    continue;
                return null;
            }

            return child;
        }
   
        public Object getObject(ByteArray mem, int offset)
        {
            Node child = getNode(mem, offset);
            if (child == null)
                return null;
            return child.getObject(mem, offset+sequence.length);
        }

        public Node setObject(Object obj, ByteArray mem, int offset, int maxOffset)
        {
            Node child = getNode(mem, offset);
            if (child == null)
                return setNode(new LeafNode(obj), mem, offset, maxOffset);

            Node result = child.setObject(obj, mem, offset+sequence.length, maxOffset);
            if (result == child)
                return this;

            return setNode(result, mem, offset, maxOffset);
        }

        public void print(String indent)
        {
	    String arrayString = "";
	    if (sequence == null)
		arrayString = "[null]";
	    else {
		for (int i = 0; i < sequence.length; i++)
		    arrayString += String.valueOf(sequence[i]) + ",";
		arrayString += "]";
	    }

            System.out.println(indent+"SEQ"+arrayString);
            child.print(indent+" ");
        }
    }

    public static class LeafNode extends Node
    {
        private int useageCount;
        private Object obj;
        
        /** Create a new leaf node */
        LeafNode(Object obj)
        {
            useageCount = 1;
            this.obj = obj;
        }

        public Node setNode(Node n, ByteArray mem, int offset, int maxOffset)
        {
            throw new IllegalStateException("Setting node on a leaf");
        }

        public Node getNode(ByteArray mem, int offset)
        {
            throw new IllegalStateException("Getting a node from a leaf");
        }

        public Object getObject(ByteArray mem, int offset)
        {
            useageCount++;
            return obj;
        }

        public Node setObject(Object obj, ByteArray mem, int offset, int maxOffset)
        {
            useageCount = 1;
            this.obj = obj;
            return this;
        }

        public int size()
        {
            return 0;
        }

        public int getUsageCount()
        {
            return useageCount;
        }

        public Object peekObject()
        {
            return obj;
        }

        public void print(String indent)
        {
            System.out.println(indent+"Leaf["+obj+"]");
        }
    }

    /**
     * Clear the entire tree.
     */
    public void clearAllObjects()
    {
        root = new WideNode();
    }

    /**
     * Get the Object that represents a x86 byte sequence (if it exists).
     *
     * @param mem memory holding a sequence of x86 bytes to search for
     * @param offset offset into memory of current x86 byte in sequence
     * @return a pointer to the code obj that represents the x86 sequnce or null if it doesn't exist
     */
    public Object getObject(ByteArray mem, int offset)
    {
        return root.getObject(mem, offset);
    }

    /**
     * Sets the Object that represents a x86 byte sequence.
     * (overwrites if already exists)
     *
     * @param obj code obj representing the sequence of x86 bytes
     * @param mem memory holding a sequence of x86 bytes to search for
     * @param offset offset into memory of current x86 byte in sequence
     * @param length x86 length of obj
     */
    public void setObject(ByteArray mem, int offset, Object obj, int length)
    {
        root = root.setObject(obj, mem, offset, offset + length - 1);
    }

    /**
     * Visits all nodes in the tree with a visitor
     *
     * @param visitor visitor for the nodes
     * @see ObjectTreeVisitor
     */
    public void visitNodes(ObjectTreeVisitor visitor)
    {
        if (root != null)
            root.visitNodes(visitor);
    }

    public void printTree()
    {
        root.print("");
    }
}