bool Tree::retrieveHelper(Node * &curr, const NodeData &nd,
NodeData * &result) const
{
if (curr != NULL)
{
// Found, sets object to passed in pointer and returns true
if (*curr->data == nd)
{
result = curr->data;
return true;
}
// Compares data to current, goes left if smaller and right if bigger
else if (*curr->data > nd)
{
return retrieveHelper(curr->left, nd, result);
}
else if (*curr->data < nd)
{
return retrieveHelper(curr->right, nd, result);
}
// Not found, returns false
else
{
return false;
}
}
else
{
return false;
}
}
//----------------------------------------------------------------------------
// retrieveHelper
// Recursive helper function for retrieve.
void BinTree::retrieveHelper(Node* current, const NodeData& item, NodeData*& found) const
{
if (current == NULL) // data does not exist
found = NULL;
else if (item == *current->data) // data exists
found = current->data;
else if (item < *current->data) // check left recursively
retrieveHelper(current->left, item, found);
else // check right recursively
retrieveHelper(current->right, item, found);
}
//----------------------------------------------------------------------------
// RetrieveHelper
// Recursive function called privately by retrieve aiding the search for data
// Item within tree
// @param curPtr current location in tree
// @param dataItem item searching for
// @param dataFound return item, NULL if not found
//
void BinTree::retrieveHelper(Node* curPtr, const Inventory & dataItem,
Inventory*& dataFound) const {
if (curPtr == NULL)
dataFound = NULL;
else if (dataItem == *curPtr->movie){
dataFound = curPtr->movie;
}
else if (dataItem < *curPtr->movie)
retrieveHelper(curPtr->left, dataItem, dataFound);
else
retrieveHelper(curPtr->right, dataItem, dataFound);
}//end retrieveHelper
//========================retrieveHelper==============================
// A helper method for retrieve. It recursively finds the provided
// object in this tree. Returns NULL if the item is not found.
//
// Preconditions: The Object is not NULL and has operator<
// implemented correctly to compare values.
//
// Postconditions: Returns a pointer to the Object if found,
// a NULL pointer is returned otherwise.
//====================================================================
const Object * BSTree::retrieveHelper (const Node *root,
const Object &the_item) const
{
if (root == NULL) return NULL;
else if (the_item == *root->item)
return root->item;
else if (the_item < *root->item)
return retrieveHelper (root->left, the_item);
else
return retrieveHelper (root->right, the_item);
}
// recursively searches (modeling on binary search) for a key
//@pre: treeptr is assigned. tkey and rest are assigned.
// post: searches for the key in the tree with treeptr's root.
// If the key is found, rest is the key together with the other
// parts of the item. Else an exception is thrown.
// usage: retrieveHelper (mroot, key, rest);
void cbstree::retrieveHelper (Cnode* treeptr, const Ckey& tkey,
Citem& rest) const throw (cexception)
{
if (treeptr == NULL)
{
throw cexception ("No matches found for the key you entered." );
} else if (tkey == treeptr-> mitem) {
rest = treeptr -> mitem;
} else if (tkey < treeptr -> mitem) {
retrieveHelper (treeptr -> mleftptr, tkey, rest);
} else {
retrieveHelper (treeptr -> mrightptr, tkey, rest);
}
}
//----------------------------------------------------------------------------
// retrieve
// Returns true if item is found and sets found pointer to that location.
bool BinTree::retrieve(const NodeData& item, NodeData*& found) const
{
retrieveHelper(root, item, found);
if (found != NULL) // if found is not NULL, it exists
return true;
else
return false;
}
//----------------------------------------------------------------------------
// Retrieve
// Locates an item within the tree by storing it in a node data item
// @param dataItem item searching for
// @param dataFound return item, NULL if not found
// @return true if dataFound not NULL, false otherwise
//
bool BinTree::retrieve(const Inventory& dataItem, Inventory*& dataFound)
const {
retrieveHelper(root, dataItem, dataFound);
if (dataFound != NULL)
return true;
else
return false;
} // end retireve
//------------------------------------------------------------------------------
// retrieve
// Retrieves a NodeData * of a given object in the tree
// (via pass-by-reference parameter)
// Returns whether found or not.
bool Tree::retrieve(const NodeData &nd, NodeData * &result) const
{
if (!isEmpty())
{
Node *temp = _root;
return retrieveHelper(temp, nd, *&result);
}
else
{
return false;
}
}
bool BSTree<DataType, KeyType>::retrieveHelper(const KeyType& searchKey,
DataType& searchDataItem,
BSTreeNode* parent) const
{
if(parent == NULL)
{
return false;
}
if(searchKey == parent->dataItem.getKey())
{
searchDataItem = parent->dataItem;
return true;
}
if(retrieveHelper(searchKey, searchDataItem, parent->left))
{
return retrieveHelper(searchKey, searchDataItem, parent->left);
}
if(retrieveHelper(searchKey, searchDataItem, parent->right))
{
return retrieveHelper(searchKey, searchDataItem, parent->right);
}
}
//========================retrieve====================================
// Finds the provided object in this tree. Returns NULL if the item
// is not found.
//
// Preconditions: The Object is not NULL and contains a valid
// ASCII character.
//
// Postconditions: Returns a pointer to the Object if found,
// a NULL pointer is returned otherwise.
//====================================================================
const Object * BSTree::retrieve (const Object &the_item) const
{
return retrieveHelper(my_root, the_item);
}
// searches for a key in a binary search tree object and
// retrieves the corresponding Cnodeitem
// pre: key has been assigned.
// post: rest contains the key with rest of the item if
// the key is found in the binary search tree object
// else an exception is thrown
// usage: bst.retrieve (key, rest);
void cbstree::retrieve (const Ckey& tkey, Citem& rest) const
throw (cexception)
{
retrieveHelper (mroot, tkey, rest);
}
bool BSTree<DataType, KeyType>::retrieve ( const KeyType& searchKey,
DataType& searchDataItem ) const
{
retrieveHelper(searchKey, searchDataItem, root);
}