From 10156ddf2c39bcd2427d2d3f0ac56ecc214fafd1 Mon Sep 17 00:00:00 2001
From: David Xia <david@davidxia.com>
Date: Sat, 15 Dec 2012 13:58:35 -0500
Subject: [PATCH] Finish doubly linked lists in Mastering Algos w C

---
 algos_with_c/ch5/dlist.c | 150 +++++++++++++++++++++++++++++++++++++++
 algos_with_c/ch5/dlist.h |  36 ++++++++++
 2 files changed, 186 insertions(+)
 create mode 100644 algos_with_c/ch5/dlist.c
 create mode 100644 algos_with_c/ch5/dlist.h

diff --git a/algos_with_c/ch5/dlist.c b/algos_with_c/ch5/dlist.c
new file mode 100644
index 0000000..5f85ae0
--- /dev/null
+++ b/algos_with_c/ch5/dlist.c
@@ -0,0 +1,150 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include "dlist.h"
+
+
+void dlist_init(DList *list, void (*destroy)(void *data)) {
+    list->size = 0;
+    list->destroy = destroy;
+    list->head = NULL;
+    list->tail = NULL;
+    return;
+}
+
+
+void dlist_destroy(DList *list) {
+    void *data;
+
+    while (dlist_size(list) > 0) {
+        if (dlist_remove(list, dlist_tail(list), (void **)&data) == 0
+            && list->destroy != NULL) {
+            list->destroy(data);
+        }
+    }
+
+    /* Clear the structure as a precaution */
+    memset(list, 0, sizeof(DList));
+    return;
+}
+
+
+int dlist_ins_next(DList *list, DListElmt *element, const void *data) {
+    DListElmt *new_element;
+
+    /* Don't allow null element unless list is empty */
+    if (element == NULL && dlist_size(list) != 0)
+        return -1;
+
+    /* Allocate storage */
+    if ((new_element = (DListElmt *) malloc(sizeof(DListElmt))) == NULL)
+        return -1;
+
+    new_element->data = (void *)data;
+
+    if (dlist_size(list) == 0) {
+        list->head = new_element;
+        list->head->prev = NULL;
+        list->head->next = NULL;
+        list->tail = new_element;
+    } else {
+        new_element->prev = element;
+        new_element->next = element->next;
+
+        if (element->next == NULL)
+            list->tail = new_element;
+        else
+            element->next->prev = new_element;
+
+        element->next = new_element;
+
+    }
+
+    list->size++;
+    return 0;
+}
+
+
+int dlist_ins_prev(DList *list, DListElmt *element, const void *data) {
+    DListElmt *new_element;
+
+    /* Don't allow null element unless list is empty */
+    if (element == NULL && dlist_size(list) != 0)
+        return -1;
+
+    /* Allocate storage */
+    if ((new_element = (DListElmt *) malloc(sizeof(DListElmt))) == NULL)
+        return -1;
+
+    new_element->data = (void *)data;
+
+    if (dlist_size(list) == 0) {
+        list->head = new_element;
+        list->head->prev = NULL;
+        list->head->next = NULL;
+        list->tail = new_element;
+    } else {
+        new_element->prev = element->prev;
+        new_element->next = element;
+
+        if (element->prev == NULL)
+            list->head = new_element;
+        else
+            element->prev->next = new_element;
+
+        element->prev = new_element;
+
+    }
+
+    list->size++;
+    return 0;
+}
+
+
+int dlist_remove(DList *list, DListElmt *element, void **data) {
+    /* Don't allow NULL element or removal from empty list */
+    if (element == NULL || dlist_size(list) == 0)
+        return -1;
+
+    *data = element->data;
+    if (element == list->head) {
+        list->head = element->next;
+
+        if (list->head == NULL)
+            list->tail = NULL;
+        else
+            element->next->prev = NULL;
+    } else {
+        element->prev->next = element->next;
+        if (element->next == NULL)
+            list->tail = element->prev;
+        else
+            element->next->prev = element->prev;
+    }
+
+    free(element);
+    list->size--;
+    return 0;
+}
+
+
+int main() {
+    DList *list = (DList *) malloc(sizeof(DList));
+    DListElmt *element = (DListElmt *) malloc(sizeof(DListElmt));
+    dlist_init(list, free);
+
+    int *data1 = (int *) malloc(sizeof(int));
+    *data1 = 4;
+    int *data2 = (int *) malloc(sizeof(int));
+    *data2 = 9;
+    dlist_ins_next(list, NULL, data1);
+    dlist_ins_prev(list, dlist_head(list), data2);
+
+    for (element = dlist_head(list); element != NULL; element = dlist_next(element)) {
+        printf("element->data = %d\n", *((int *) element->data));
+    }
+
+    dlist_destroy(list);
+    return 0;
+}
+
diff --git a/algos_with_c/ch5/dlist.h b/algos_with_c/ch5/dlist.h
new file mode 100644
index 0000000..3bd6088
--- /dev/null
+++ b/algos_with_c/ch5/dlist.h
@@ -0,0 +1,36 @@
+#ifndef DLIST_H
+#define DLIST_H
+
+#include <stdlib.h>
+
+
+typedef struct DListElmt_ {
+    void *data;
+    struct DListElmt_ *prev;
+    struct DListElmt_ *next;
+} DListElmt;
+
+typedef struct DList_ {
+    int size;
+    int (*match)(const void *key1, const void *key2);
+    void (*destroy)(void *data);
+    DListElmt *head;
+    DListElmt *tail;
+} DList;
+
+/* Public interface */
+void dlist_init(DList *list, void (*destroy)(void *data));
+void dlist_destroy(DList *list);
+int dlist_ins_next(DList *list, DListElmt *element, const void *data);
+int dlist_ins_prev(DList *list, DListElmt *element, const void *data);
+int dlist_remove(DList *list, DListElmt *element, void **data);
+#define dlist_size(list) ((list)->size)
+#define dlist_head(list) ((list)->head)
+#define dlist_tail(list) ((list)->tail)
+#define dlist_is_head(element) ((element)->prev == NULL ? 1 : 0)
+#define dlist_is_tail(element) ((element)->next == NULL ? 1 : 0)
+#define dlist_data(element) ((element)->data)
+#define dlist_next(element) ((element)->next)
+#define dlist_prev(element) ((element)->prev)
+#endif
+