Add initial version of LinkedList C module

linkedlist.c

@@ -0,0 +1,234 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Type Definitions ////////////////////////////////////////////////////////////////////////////////
+
+typedef struct LinkedListNode LinkedListNode;
+
+struct LinkedListNode {
+  int value;
+  LinkedListNode *next;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Memory Management ///////////////////////////////////////////////////////////////////////////////
+
+// Create a new linked list with a given value
+LinkedListNode* LinkedList_new(int value) {
+  LinkedListNode *head = malloc(sizeof(LinkedListNode));
+  head->value = value;
+  head->next = NULL;
+  return head;
+}
+
+// Free all the nodes in a linked list
+LinkedListNode* LinkedList_free(LinkedListNode *head) {
+  if (head == NULL) return NULL;
+
+  LinkedListNode *current = head;
+  LinkedListNode *toDelete = NULL;
+
+  while (current != NULL) {
+    toDelete = current;
+    current = current->next;
+    free(toDelete);
+  }
+
+  return NULL;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Mutation ////////////////////////////////////////////////////////////////////////////////////////
+
+// Add a value to the start of the linked list
+LinkedListNode* LinkedList_prepend(LinkedListNode *head, int value) {
+  LinkedListNode *newHead = LinkedList_new(value);
+  newHead->next = head;
+  return newHead;
+}
+
+// Add a value to the end of the linked list
+LinkedListNode* LinkedList_append(LinkedListNode *head, int value) {
+  if (head == NULL) return NULL;
+
+  LinkedListNode *current = head;
+  while (current->next != NULL) {
+    current = current->next;
+  }
+
+  current->next = LinkedList_new(value);
+
+  return head;
+}
+
+// Remove a value from the start of the linked list
+LinkedListNode* LinkedList_pull(LinkedListNode *head, int *shiftedValue) {
+  if (head == NULL) return NULL;
+
+  *shiftedValue = head->value;
+
+  LinkedListNode *toDelete = head;
+  head = head->next;
+  toDelete->next = NULL;
+  LinkedList_free(toDelete);
+
+  return head;
+}
+
+// Remove a value from the end of the linked list
+LinkedListNode* LinkedList_pop(LinkedListNode *head, int *poppedValue) {
+  if (head == NULL) return NULL;
+
+  LinkedListNode *current = head;
+  LinkedListNode *prior = NULL;
+  while (current->next != NULL) {
+    prior = current;
+    current = current->next;
+  }
+
+  *poppedValue = current->value;
+
+  if (prior != NULL) {
+    prior->next = LinkedList_free(current);
+  } else {
+    head = LinkedList_free(head);
+  }
+
+  return head;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Query ///////////////////////////////////////////////////////////////////////////////////////////
+
+// Determines whether a value exists in the list
+bool LinkedList_contains(LinkedListNode *head, int value) {
+  LinkedListNode *current = head;
+  while (current != NULL) {
+    if (current->value == value) return true;
+    current = current->next;
+  }
+
+  return false;
+}
+
+// Determines the number of nodes in the list
+int LinkedList_length(LinkedListNode *head) {
+  int result = 0;
+  LinkedListNode *current = head;
+  while (current != NULL) {
+    current = current->next;
+    result++;
+  }
+
+  return result;
+}
+
+// Prints the list to the console
+void LinkedList_print(LinkedListNode *head) {
+  LinkedListNode *current = head;
+  while (current != NULL) {
+    printf("(%d)->", current->value);
+    current = current->next;
+  }
+  printf("NULL");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Tests ///////////////////////////////////////////////////////////////////////////////////////////
+
+LinkedListNode *buildTest() {
+  LinkedListNode *head = LinkedList_new(42);
+  head = LinkedList_append(head, 43);
+  head = LinkedList_append(head, 44);
+  return head;
+}
+
+void test_prepend() {
+  printf("Running test: prepend\n");
+  LinkedListNode *head = LinkedList_new(42);
+  head = LinkedList_prepend(head, 43);
+  head = LinkedList_prepend(head, 44);
+  LinkedList_print(head); printf("    should be    (44)->(43)->(42)->NULL\n");
+
+  head = LinkedList_free(head);
+  printf("\n");
+}
+
+void test_append() {
+  printf("Running test: append\n");
+  LinkedListNode *head = buildTest();
+  LinkedList_print(head); printf("    should be    (42)->(43)->(44)->NULL\n");
+
+  head = LinkedList_free(head);
+  printf("\n");
+}
+
+void test_pull() {
+  printf("Running test: pull\n");
+  LinkedListNode *head = buildTest();
+
+  int value = 0;
+  head = LinkedList_pull(head, &value);
+  printf("%d    should be    42\n", value);
+  LinkedList_print(head); printf("    should be    (43)->(44)->NULL\n");
+  head = LinkedList_pull(head, &value);
+  printf("%d    should be    43\n", value);
+  LinkedList_print(head); printf("    should be    (44)->NULL\n");
+  head = LinkedList_pull(head, &value);
+  printf("%d    should be    44\n", value);
+  LinkedList_print(head); printf("    should be    NULL\n");
+
+  head = LinkedList_free(head);
+  printf("\n");
+}
+
+void test_pop() {
+  printf("Running test: pop\n");
+  LinkedListNode *head = buildTest();
+
+  int value = 0;
+  head = LinkedList_pop(head, &value);
+  printf("%d    should be    44\n", value);
+  LinkedList_print(head); printf("    should be    (42)->(43)->NULL\n");
+  head = LinkedList_pop(head, &value);
+  printf("%d    should be    43\n", value);
+  LinkedList_print(head); printf("    should be    (42)->NULL\n");
+  head = LinkedList_pop(head, &value);
+  printf("%d    should be    42\n", value);
+  LinkedList_print(head); printf("    should be    NULL\n");
+
+  head = LinkedList_free(head);
+  printf("\n");
+}
+
+void test_contains() {
+  printf("Running test: contains\n");
+  LinkedListNode *head = buildTest();
+
+  printf("%s    should be    true\n", LinkedList_contains(head, 43) ? "true" : "false");
+  printf("%s    should be    false\n", LinkedList_contains(head, 90) ? "true" : "false");
+
+  head = LinkedList_free(head);
+  printf("\n");
+}
+
+void test_length() {
+  printf("Running test: length\n");
+  LinkedListNode *head = buildTest();
+
+  printf("%d    should be    3\n", LinkedList_length(head));
+  
+  head = LinkedList_free(head);
+  printf("\n");
+}
+
+int main() {
+  test_prepend();
+  test_append();
+  test_pull();
+  test_pop();
+  test_contains();
+  test_length();
+}