Binary Search Tree

BinarySearchTree.h

#ifndef BINARY_SEARCH_TREE_H
#define BINARY_SEARCH_TREE_H

#include "dsexceptions.h"
#include <algorithm>
using namespace std;       

template <typename Comparable>
class BinarySearchTree
{
  public:
    BinarySearchTree( ) : root{ nullptr } { }
  
    BinarySearchTree( const BinarySearchTree & rhs ) : root{ nullptr }
    {
        root = clone( rhs.root );
    }

    BinarySearchTree( BinarySearchTree && rhs ) : root{ rhs.root }
    {
        rhs.root = nullptr;
    }
    
    ~BinarySearchTree( )
    {
        makeEmpty( );
    }

    BinarySearchTree & operator=( const BinarySearchTree & rhs )
    {
        BinarySearchTree copy = rhs;
        std::swap( *this, copy );
        return *this;
    }
        
    BinarySearchTree & operator=( BinarySearchTree && rhs )
    {
        std::swap( root, rhs.root );       
        return *this;
    }
    
    const Comparable & findMin( ) const
    {
        if( isEmpty( ) )
            throw UnderflowException{ };
        return findMin( root )->element;
    }

    const Comparable & findMax( ) const
    {
        if( isEmpty( ) )
            throw UnderflowException{ };
        return findMax( root )->element;
    }

    bool contains( const Comparable & x ) const
    {
        return contains( x, root );
    }

    bool isEmpty( ) const
    {
        return root == nullptr;
    }

    void printTree( ostream & out = cout ) const
    {
        if( isEmpty( ) )
            out << "Empty tree" << endl;
        else
            printTree( root, out );
    }

    void makeEmpty( )
    {
        makeEmpty( root );
    }

    void insert( const Comparable & x )
    {
        insert( x, root );
    }
     
    void insert( Comparable && x )
    {
        insert( std::move( x ), root );
    }
    
    void remove( const Comparable & x )
    {
        remove( x, root );
    }


  private:
    struct BinaryNode
    {
        Comparable element;
        BinaryNode *left;
        BinaryNode *right;

        BinaryNode( const Comparable & theElement, BinaryNode *lt, BinaryNode *rt )
          : element{ theElement }, left{ lt }, right{ rt } { }
        
        BinaryNode( Comparable && theElement, BinaryNode *lt, BinaryNode *rt )
          : element{ std::move( theElement ) }, left{ lt }, right{ rt } { }
    };

    BinaryNode *root;

    void insert( const Comparable & x, BinaryNode * & t )
    {
        if( t == nullptr )
            t = new BinaryNode{ x, nullptr, nullptr };
        else if( x < t->element )
            insert( x, t->left );
        else if( t->element < x )
            insert( x, t->right );
        else
            ;  // Duplicate; do nothing
    }
    
    void insert( Comparable && x, BinaryNode * & t )
    {
        if( t == nullptr )
            t = new BinaryNode{ std::move( x ), nullptr, nullptr };
        else if( x < t->element )
            insert( std::move( x ), t->left );
        else if( t->element < x )
            insert( std::move( x ), t->right );
        else
            ;  // Duplicate; do nothing
    }

    void remove( const Comparable & x, BinaryNode * & t )
    {
        if( t == nullptr )
            return;   // Item not found; do nothing
        if( x < t->element )
            remove( x, t->left );
        else if( t->element < x )
            remove( x, t->right );
        else if( t->left != nullptr && t->right != nullptr ) // Two children
        {
            t->element = findMin( t->right )->element;
            remove( t->element, t->right );
        }
        else
        {
            BinaryNode *oldNode = t;
            t = ( t->left != nullptr ) ? t->left : t->right;
            delete oldNode;
        }
    }

    BinaryNode * findMin( BinaryNode *t ) const
    {
        if( t == nullptr )
            return nullptr;
        if( t->left == nullptr )
            return t;
        return findMin( t->left );
    }

    BinaryNode * findMax( BinaryNode *t ) const
    {
        if( t != nullptr )
            while( t->right != nullptr )
                t = t->right;
        return t;
    }

    bool contains( const Comparable & x, BinaryNode *t ) const
    {
        if( t == nullptr )
            return false;
        else if( x < t->element )
            return contains( x, t->left );
        else if( t->element < x )
            return contains( x, t->right );
        else
            return true;    // Match
    }

    void makeEmpty( BinaryNode * & t )
    {
        if( t != nullptr )
        {
            makeEmpty( t->left );
            makeEmpty( t->right );
            delete t;
        }
        t = nullptr;
    }

    void printTree( BinaryNode *t, ostream & out ) const
    {
        if( t != nullptr )
        {
            printTree( t->left, out );
            out << t->element << endl;
            printTree( t->right, out );
        }
    }

    BinaryNode * clone( BinaryNode *t ) const
    {
        if( t == nullptr )
            return nullptr;
        else
            return new BinaryNode{ t->element, clone( t->left ), clone( t->right ) };
    }
};

#endif