some code experiments

tmp/bTree.h

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+/* B-Tree
+ * Author:	Caleb Baker
+ * Date:	10/8/17
+ * Summary:	A B-Tree data structure.
+ *			Most standard operations run in O(lg(n)) time.
+ *			Uses O(n) memory.
+ *			Where n is the number of items in the tree.
+ */
+
+
+#pragma once
+
+#include <utility>
+
+// #define NULL 0
+#define SEARCH_KEY_NOT_FOUND 's'
+#define REMOVE_KEY_NOT_FOUND 'r'
+
+
+// struct for representing nodes of a b tree
+template <typename T>
+struct BNode {
+	BNode<T> **child;	// Array of pointers to children.
+	T *key;				// Array of keys.
+	unsigned size;		// Number of keys.
+	bool leaf;			// Whether the node is a leaf.
+};
+
+
+typedef char BTREE_EXCEPTION;
+
+
+// class for representing b trees.
+template <typename T>
+class BTree {
+public:
+	// Constructor
+	// First parameter is the minimum degree of the tree.
+	// Second parameter is the tree's key-comparison function.
+	// Third parameter is a function that prints keys.
+	// Constant time.
+	BTree(unsigned, bool (*)(T, T), void (*)(T) = NULL);
+
+	// Destructor.
+	// Linear time.
+	~BTree<T>();
+
+	// Inserts a key into the tree.
+	// Logorithmic time.
+	void insert(T);
+
+	// Removes a key from the tree.
+	// Throws a BTREE_EXCEPTION if no item was found to remove.
+	// Logorithmic time.
+	T remove(T);
+
+	// Function to find a key in the tree.
+	// returnValue.first is the node the item is in.
+	// returnValue.second is the correct index in that node's key array
+	// Logorithmic time.
+	std::pair<BNode<T>*, unsigned> search(T);
+
+	// Uses search but just returns the key rather than the whole node.
+	// Useful when T is a key value pair and lessThan only looks at the key.
+	// Throws a BTREE_EXCEPTION if no item matching the parameter is found
+	// Logorithmic time.
+	T searchKey(T);
+
+	// Prints the tree.
+	// Linear time
+	void print();
+
+private:
+
+	// Used for initializing nodes.
+	void initializeNode(BNode<T>*);
+
+	// Recursive function called by destructor.
+	void freeNode(BNode<T>*);
+
+	// Finds the index of a key in a node.
+	unsigned findIndex(BNode<T>*, T);
+
+	// Inserts a key into a node.
+	unsigned nodeInsert(BNode<T>*, T);
+
+	// Deletes the key at a given index from a node.
+	T nodeDelete(BNode<T>*, unsigned);
+
+	// Function for splitting nodes that are too full.
+	void splitChild(BNode<T>*, int);
+
+	// Merges two children of a node at a given index into one child.
+	char mergeChildren(BNode<T>*, unsigned);
+
+	// Makes sure the child of a node at a specified index has >= minDegree items.
+	char fixChildSize(BNode<T>*, unsigned);
+
+	// Recursively prints a subtree.
+	void printNode(BNode<T>*, unsigned);
+
+	// Root node.
+	BNode<T> *root;
+
+	// Comparison function used for managing element placement.
+	bool (*lessThan)(T, T);
+
+	// Function used to print items in the tree.
+	void (*printKey)(T);
+
+	// Minimum degree of the tree.
+	unsigned minDegree;
+};
+
+
+#include "bTree.cpp"