136 lines
3.5 KiB
C
136 lines
3.5 KiB
C
#include <stdlib.h>
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#include <string.h>
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#include "bintree.h"
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#include "stack.h"
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/* Adds a copy of data's pointer destination to the tree using compareFct for ordering. Accepts duplicates
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if isDuplicate is NULL, otherwise ignores duplicates and sets isDuplicate to 1 (or to 0 if a new entry is added). */
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TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFctType compareFct, int *isDuplicate)
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{
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if (compareFct == NULL || data == NULL || dataSize == 0)
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return root; // invalid input: do nothing
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if (root == NULL)
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{
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TreeNode *node = (TreeNode *)malloc(sizeof(TreeNode));
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if (node == NULL)
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return NULL; // allocation failed
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node->data = malloc(dataSize);
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if (node->data == NULL)
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{
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free(node);
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return NULL;
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}
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memcpy(node->data, data, dataSize);
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node->left = NULL;
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node->right = NULL;
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if (isDuplicate != NULL)
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*isDuplicate = 0;
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return node;
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}
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int cmp = compareFct(data, root->data);
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if (cmp < 0)
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{
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root->left = addToTree(root->left, data, dataSize, compareFct, isDuplicate);
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}
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else if (cmp > 0)
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{
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root->right = addToTree(root->right, data, dataSize, compareFct, isDuplicate);
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}
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else // cmp == 0 -> duplicate
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{
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if (isDuplicate != NULL)
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{
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*isDuplicate = 1;
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// ignore duplicate insertion
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}
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else
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{
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// duplicates allowed: insert to right subtree for stability
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root->right = addToTree(root->right, data, dataSize, compareFct, isDuplicate);
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}
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}
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return root;
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}
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/* Iterates over the tree given by root in-order (ascending order).
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Follows the usage of strtok: If root != NULL then create/reset iterator for that tree.
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If root == NULL, continue iteration from last position.
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Uses stack to manage traversal state. */
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void *nextTreeData(TreeNode *root)
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{
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// static iterator state
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static StackNode *iterStack = NULL;
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static TreeNode *currentRoot = NULL;
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// initialize iterator for a new tree
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if (root != NULL)
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{
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// clear any previous iterator state
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clearStack(iterStack);
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iterStack = NULL;
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currentRoot = root;
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// push root and all its left descendants
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TreeNode *cur = root;
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while (cur != NULL)
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{
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iterStack = push(iterStack, cur);
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cur = cur->left;
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}
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}
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else
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{
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// if user asks to continue but iterator not initialized, nothing to return
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if (iterStack == NULL)
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return NULL;
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}
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// get next node
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if (iterStack == NULL)
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return NULL;
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// pop the top node
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TreeNode *node = (TreeNode *)top(iterStack);
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iterStack = pop(iterStack);
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// after popping node, push its right child and all left descendants of that right child
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TreeNode *r = node->right;
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while (r != NULL)
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{
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iterStack = push(iterStack, r);
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r = r->left;
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}
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return node->data;
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}
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/* Releases all memory resources (including data copies). */
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void clearTree(TreeNode *root)
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{
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if (root == NULL)
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return;
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if (root->left != NULL)
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clearTree(root->left);
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if (root->right != NULL)
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clearTree(root->right);
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free(root->data);
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root->data = NULL;
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free(root);
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}
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/* Returns the number of entries in the tree given by root. */
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unsigned int treeSize(const TreeNode *root)
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{
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if (root == NULL)
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return 0;
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return 1 + treeSize(root->left) + treeSize(root->right);
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}
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