make the list a type itself

linked-list.c

@@ -3,17 +3,27 @@
 #include <stdlib.h>
 #include "assert.h"
 
+
 struct list_node {
   int data;
   struct list_node *next;
 };
 typedef struct list_node list_node_t;
 
-int list_length(list_node_t * list) {
+struct list {
+  list_node_t * head;
+};
+typedef struct list list_t;
+
+void list_init (list_t * list) {
+  list->head = NULL;
+}
+
+int list_length(list_t * list) {
   list_node_t *cur;
   int count = 0;
 
-  cur = list;
+  cur = list->head;
   while (cur != NULL) {
     count++;
     cur = cur->next;
@@ -22,14 +32,14 @@ int list_length(list_node_t * list) {
   return count;
 }
 
-bool list_empty(list_node_t * list) {
+bool list_empty(list_t * list) {
-  return (list == NULL);
+  return (list->head == NULL);
 }
 
-void list_print(list_node_t * list) {
+void list_print(list_t * list) {
   list_node_t *cur;
 
-  cur = list;
+  cur = list->head;
   while (cur != NULL) {
     printf("%d ", cur->data);
     cur = cur->next;
@@ -37,22 +47,29 @@ void list_print(list_node_t * list) {
   printf("\n");
 }
 
-void list_add(list_node_t * list, list_node_t * item) {
+void list_add(list_t * list, list_node_t * item) {
   list_node_t *cur;
 
-  cur = list;
+  if (list_empty(list)) {
-  assert(cur != NULL);
+    list->head = item;
+  } else {
+    cur = list->head;
     while (cur->next != NULL) {
       cur = cur->next;
     }
-
     cur->next = item;
+  }
 }
 
-void list_remove(list_node_t * list, list_node_t * item) {
+void list_remove(list_t * list, list_node_t * item) {
   list_node_t *cur;
 
-  cur = list;
+  if (list->head->data == item->data) {
+    list->head = list->head->next;
+    return;
+  }
+
+  cur = list->head;
   assert(cur != NULL);
 
   while (cur->next != NULL) {
@@ -64,28 +81,34 @@ void list_remove(list_node_t * list, list_node_t * item) {
   }
 }
 
+/* FIXME
+ * list_node_t list_revert(list_node_t *list) {
+} */
+
 int main(int argc, char *argv[]) {
-  list_node_t *emptylist = NULL;
+  list_t *emptylist = malloc(sizeof(list_t));
+  list_init(emptylist);
   assert(list_length(emptylist) == 0);
   assert(list_empty(emptylist) == true);
   list_print(emptylist);
   printf("list_length = %d\n", list_length(emptylist));
 
+  list_t *foolist = malloc(sizeof(list_t));
   list_node_t foo = { 1, NULL };
+  list_add(foolist, &foo);
 
-  assert(list_length(&foo) == 1);
+  assert(list_length(foolist) == 1);
-  assert(list_empty(&foo) == false);
+  assert(list_empty(foolist) == false);
-  list_print(&foo);
+  list_print(foolist);
-  printf("list_length = %d\n", list_length(&foo));
+  printf("list_length = %d\n", list_length(foolist));
 
   // append something to foo
   list_node_t bar = { 2, NULL };
-  list_add(&foo, &bar);
+  list_add(foolist, &bar);
 
-  assert(list_length(&foo) == 2);
+  assert(list_length(foolist) == 2);
-  assert(list_length(&bar) == 1);
+  list_print(foolist);
-  list_print(&foo);
+  printf("list_length = %d\n", list_length(foolist));
-  printf("list_length = %d\n", list_length(&foo));
 
   // append more
   const int howmany = 100;
@@ -93,31 +116,54 @@ int main(int argc, char *argv[]) {
     list_node_t *newnode = malloc(sizeof(list_node_t));
     newnode->data = i;
 
-    list_add(&foo, newnode);
+    list_add(foolist, newnode);
   }
-  assert(list_length(&foo) == 2 + howmany);
+  assert(list_length(foolist) == 2 + howmany);
-  list_print(&foo);
+  list_print(foolist);
-  printf("list_length = %d\n", list_length(&foo));
+  printf("list_length = %d\n", list_length(foolist));
 
   // remove something
   list_node_t toremove = { 23, NULL };
-  list_remove(&foo, &toremove);
+  list_remove(foolist, &toremove);
-  assert(list_length(&foo) == 2 + howmany - 1);
+  assert(list_length(foolist) == 2 + howmany - 1);
-  list_print(&foo);
+  list_print(foolist);
-  printf("list_length = %d\n", list_length(&foo));
+  printf("list_length = %d\n", list_length(foolist));
+
+  // remove last item
+  toremove.data = howmany - 1;
+  list_remove(foolist, &toremove);
+  assert(list_length(foolist) == 2 + howmany - 2);
+  list_print(foolist);
+  printf("list_length = %d\n", list_length(foolist));
 
   // remove something
-  toremove.data = 99;
+  toremove.data = 1;
-  list_remove(&foo, &toremove);
+  list_remove(foolist, &toremove);
-  assert(list_length(&foo) == 2 + howmany - 2);
+  assert(list_length(foolist) == 2 + howmany - 3);
-  list_print(&foo);
+  list_print(foolist);
-  printf("list_length = %d\n", list_length(&foo));
+  printf("list_length = %d\n", list_length(foolist));
 
   // remove something
   toremove.data = 1;
-  list_remove(&foo, &toremove);
+  list_remove(foolist, &toremove);
-  /* FIXME can't delete first 1 */
+  assert(list_length(foolist) == 2 + howmany - 4);
-  assert(list_length(&foo) == 2 + howmany - 3);
+  list_print(foolist);
-  list_print(&foo);
+  printf("list_length = %d\n", list_length(foolist));
-  printf("list_length = %d\n", list_length(&foo));
+
+  /* remove everything */
+  for (int i = 0; i < howmany; i++) {
+    toremove.data = i;
+    list_remove(foolist, &toremove);
+  }
+  assert(list_length(foolist) == 1);
+  list_print(foolist);
+  printf("list_length = %d\n", list_length(foolist));
+
+  /* remove last remaining item */
+  toremove.data = 2;
+  list_remove(foolist, &toremove);
+  assert(list_length(foolist) == 0);
+  assert(list_empty(foolist) == true);
+  list_print(foolist);
+  printf("list_length = %d\n", list_length(foolist));
 }