bt_builder.h

// 91574 Database II - C++ Programming
// Swathi Kurunji, UMass Lowell, MA, 2011
// bt_builder.h - definition of class BtreeBuilder for this project.

#ifndef BT_BUILDER_H
#define BT_BUILDER_H

#include<iostream>
#include<cstdlib>
using namespace std;

#include "bt_errors.h"
#include "bt_node.h"
#include "bt_leaf.h"
#include "bt_index.h"
#include "bt_scan.h"

class BtreeBuilder
{

		BtreeNode *root;   //will point to root of the tree

	public:
		BtreeBuilder()
		{
			BtreeLeaf * btl = new BtreeLeaf();
			root = btl;
		};

		virtual ~BtreeBuilder();

		friend class BtreeScan;

		//this function inserts key into B+ tree
		//this traverses from root until leaf node is reached.
		//inserts the key. If required splits node and propagates the split
		//until a node which does not need split is reached
		Status insertBuilderKey( KeyId );

		//deletes the specified key from the tree
		Status deleteBuilderKey( KeyId );

		Status searchForLeafNode( KeyId, BtreeNode*, BtreeNode*&);

		//1st argument(arg) is the key that we need to insert
		//In 2nd arg, we store the key value that we need to insert in parent node after splitting node
		//3rd is the node which is full and needs split
		//4th and 5th holds the new left and right child address(we need to store this in parent node)
		Status splitNode( KeyId, KeyId&, BtreeNode *, BtreeNode *&, BtreeNode *& );

		// create a scan with given keys
		// Cases:
		//      (1) lo_key = NULL, hi_key = NULL
		//              scan the whole index
		//      (2) lo_key = NULL, hi_key!= NULL
		//              range scan from min to the hi_key
		//      (3) lo_key!= NULL, hi_key = NULL
		//              range scan from the lo_key to max
		//      (4) lo_key!= NULL, hi_key!= NULL, lo_key = hi_key
		//              exact match ( might not unique)
		//      (5) lo_key!= NULL, hi_key!= NULL, lo_key < hi_key
		//              range scan from lo_key to hi_key
		BtreeScan* openScan( KeyId lo_key = NULL, KeyId hi_key = NULL );

		//find the starting position.
		//scanTree function calls this function by passing lo_key to find the starting position in the B+tree.
		//input are: pointer of scan object and lo_key
		Status findStartPosition( BtreeScan *, KeyId );

		//This function recursively deletes the whole B+tree
		Status destroyBtree();

};

#endif