enh(C): add more functions to gl-threads.c (#566)

algorithms/C/linked-lists/gl-threads.c

@@ -31,25 +31,12 @@
  * @author [Ashborn-SM](https://github.com/Ashborn-SM)
  */
 
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
+#include <stdlib.h> // for dynamic memory allocation 
+#include <stdio.h> // for IO operations
+#include <string.h> // for string manipulation
 
 #define HEAD(list) (list->head)
 #define OFFSETOF(structure, field) (long)&((structure*)0)->field
-#define POP_FRONT(list, structure, offset){                     \
-    glthread_node* _cur = HEAD(list), *temp = HEAD(list)->next; \
-    structure* per = (structure*)((char*)_cur - offset);        \
-    free(per);                                                  \
-    HEAD(list) = temp;                                          \
-}
-#define ITERATE_GL_THREADS_BEGIN(lstptr, struct_type, ptr)      \
-{                                                               \
-    glthread_node *_glnode = NULL, *_next = NULL;               \
-    for(_glnode = lstptr->head; _glnode; _glnode = _next){      \
-        _next = _glnode->next;                                  \
-        ptr = (struct_type *)((char *)_glnode - lstptr->offset);
-#define END }}
 
 /**
  * @struct glthread_node
@@ -66,6 +53,9 @@ typedef struct glthread_node_{
  */
 typedef struct{
     glthread_node* head;
+    size_t size;
+    // store the addresses of all the nodes in linked-list
+    char** addresses;
     unsigned int offset;
 }gldll;
 
@@ -73,6 +63,7 @@ typedef struct{
  * @brief initialise the node
  * @details set the node members to NULL
  * @param node linked-list node
+ * @returns void
  */
 void init_glthread_node(glthread_node* node){
     node->next = NULL;
@@ -84,9 +75,12 @@ void init_glthread_node(glthread_node* node){
  * @details set the head and offset
  * @param list linked-list
  * @param offset offset of the data member
+ * @returns void
  */
 void init_glthread_list(gldll* list, unsigned int offset){
     list->head = NULL;
+    list->size = 0;
+    list->addresses = NULL;
     list->offset = offset;
 }
 
@@ -95,9 +89,11 @@ void init_glthread_list(gldll* list, unsigned int offset){
  * @details insert the node at the front of the list
  * @param list linked-list
  * @param node node to be inserted
+ * @returns void
  */
 void glthread_pushfront(gldll* list, glthread_node* node){
     glthread_node* cur = HEAD(list);
+    list->size++;
     if(cur == NULL){
         HEAD(list) = node;
         return;
@@ -107,6 +103,47 @@ void glthread_pushfront(gldll* list, glthread_node* node){
     HEAD(list) = node;
 }
 
+/**
+ * @brief delete the node at front
+ * @details delete the head node and point the head to the next node
+ * @param list based doubly linked-list
+ * @returns void
+ */
+void glthread_popfront(gldll* list){
+    if(list == NULL || HEAD(list) == NULL ){ return; }
+    glthread_node* temp = HEAD(list)->next;
+    free((char*)HEAD(list) - list->offset); 
+    HEAD(list) = temp;
+    if(HEAD(list) != NULL){
+        temp->prev = NULL;
+    }
+    list->size--;
+}
+
+/**
+ * @brief return the addresses of all nodes in the linked-list
+ * @param list based doubly linked-list
+ * @return addresses of all nodes in the linked-list starting from head
+ */
+char** get_addresses(gldll* list){
+    if(list->addresses != NULL){ 
+        // free the memory in order to avoid memory leak
+        free(list->addresses);
+    }
+    list->addresses = malloc(list->size*sizeof(char*));
+	if(list->addresses == NULL){
+		printf("Allocation Failure");
+		exit(0);
+	}
+    glthread_node* cur = HEAD(list);
+    for(int i=0; cur != NULL; i++){
+        list->addresses[i] = (char*)cur - list->offset; 
+        cur = cur->next;
+    }
+
+    return list->addresses;
+}
+
 /**
  * @struct person 
  * @brief a structure with attributes of a person
@@ -120,6 +157,7 @@ typedef struct{
 /**
  * @brief print the details of the person
  * @param per person structure
+ * @returns void
  */
 void print(person* per){
     printf("Name: %s\n", per->name);
@@ -143,17 +181,19 @@ person* allocate(){
 }
 
 /**
- * @brief test the program
+ * @brief Self-test the implementation
  * @param list linked-list
+ * @returns void
  */
-void test(gldll* list){
+static void test(gldll* list){
+	if(HEAD(list) == NULL){
+		return;
+	}
 	char passed[10] = "[PASSED]:\0";
 	char failed[10] = "[FAILED]:\0";
 	char expected[9] = "EXPECTED\0";
 	char returned[9] = "RETURNED\0";
-	glthread_node* cur = HEAD(list);
-	person* per = NULL;
-	ITERATE_GL_THREADS_BEGIN(list, person, per){
+	person* per = (person*)((char*)HEAD(list)- list->offset);
 	if(strcmp(per->name, "rohit") == 0){
 		printf("%s: %s -> %s, %s -> %s\n", passed, expected, "rohit",
 		returned, per->name);
@@ -186,10 +226,24 @@ void test(gldll* list){
 		printf("%s: %s -> %i, %s -> %i\n", failed, expected, 67,
 		returned, per->weight);
 	}
-        break;
-	}END;
 }
 
+/**
+ * @brief free all the memory allocated for the doubly linked-list
+ * @param list doubly linked-list
+ * @returns void
+ */
+void destructor(gldll** list){
+    while(HEAD((*list))!= NULL){
+        glthread_popfront((*list));
+    }
+    free(*list);
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
 int main(){
 	gldll* list = malloc(sizeof(*list));
 	if(list == NULL){
@@ -220,24 +274,15 @@ int main(){
 	glthread_pushfront(list, &(rohit->glnode));
 	glthread_pushfront(list, &(rahul->glnode));
 
-    person* temp = NULL;
-    ITERATE_GL_THREADS_BEGIN(list, person, temp){
-        // uncomment the below line to print the details of the person
-        print(temp);
-    }END;
-    /*
-        Output:
-            Name: rahul
-            Height: 170
-            Age:19
-            Weight: 60
-            -------------
-            Name: rohit
-            Height: 174
-            Age: 23
-            Weight: 77
-            -------------
-    */
-    POP_FRONT(list, person, OFFSETOF(person, glnode));
-	test(list);
+	char** addresses = get_addresses(list);
+	for(int i=0; i<list->size; i++){
+		print((person*)addresses[i]);
+	}
+
+	glthread_popfront(list);
+
+	test(list);
+
+	destructor(&list);
+	return 0;
 }