C 言語の話#4 リスト

リストを林檎生活100: C 言語の話#3 オブジェクト指向プログラミング？のように実装．まあ，スタック的操作しか実装してないけどｗイテレータもやればできるもんだね．

/* main.c */
#include <stdio.h>
#include <string.h>
#include "book.h"
#include "list.h"

int main(void)
{
    List *books;
    Book *book;
    Iterator *it;

    books = newList();

    books->push(books, newBook("伝奇集", "J.L. ボルヘス"));
    books->push(books, newBook("ぼく、オタリーマン。", "よしたに"));
    books->push(books, newBook("ブタのいどころ", "小泉吉宏"));

    it = newIterator(books);
    while (it->hasNext(it)) {
        book = it->next(it);
        printf("%s\t%s\n", book->getTitle(book), book->getAuthor(book));
    }
    deleteIterator(it);

    while ((book = books->pop(books)) != NULL)
        deleteBook(book);

    deleteList(books);

    return 0;
}

/* list.h */
#ifndef __LIST_H__
#define __LIST_H__

typedef struct _List List;
typedef struct _Iterator Iterator;
typedef struct _Element Element;

struct _List {
    Element *first;
    int ((*push)(List *list, void *data));
    void *((*pop)(List *list));
};

struct _Iterator {
    Element *e;
    int ((*hasNext)(const Iterator *it));
    void *((*next)(Iterator *it));
};

List *newList(void);
void deleteList(List *list);

Iterator *newIterator(List *list);
void deleteIterator(Iterator *it);

#endif /* __LIST_H__ */

/* list.c */
#include 
#include 
#include "list.h"

struct _Element {
    Element *next;
    void *data;
};

int list_push(List *list, void *data);
void *list_pop(List *list);

int iterator_hasNext(const Iterator *it);
void *iterator_next(Iterator *it);

Element *newElement(Element *e, void *data);
void deleteElement(Element *e);

List *newList(void)
{
    List *list;

    list = (List *)malloc(sizeof(List));
    if (list == NULL) {
        fprintf(stderr, "%s:%d: error: %s()\n", __FILE__, __LINE__, __func__);
        return NULL;
    }

    list->first = NULL;

    list->push = list_push;
    list->pop = list_pop;

    return list;
}

void deleteList(List *list)
{
    free(list);
}

int list_push(List *list, void *data)
{
    Element *e;

    e = newElement(list->first, data);
    if (e == NULL) {
        fprintf(stderr, "%s:%d: error: %s()\n", __FILE__, __LINE__, __func__);
        return -1;
    }

    list->first = e;

    return 0;
}

void *list_pop(List *list)
{
    Element *e;
    void *data;

    if (list->first == NULL)
        return NULL;

    e = list->first;
    data = e->data;
    list->first = e->next;

    deleteElement(e);

    return data;
}

Iterator *newIterator(List *list)
{
    Iterator *it;

    it = (Iterator *)malloc(sizeof(Iterator));
    if (it == NULL) {
        fprintf(stderr, "%s:%d: error: %s()\n", __FILE__, __LINE__, __func__);
        return NULL;
    }

    it->e = list->first;

    it->hasNext = iterator_hasNext;
    it->next = iterator_next;

    return it;
}

void deleteIterator(Iterator *it)
{
    free(it);
}

int iterator_hasNext(const Iterator *it)
{
    return it->e != NULL ? 1 : 0;
}

void *iterator_next(Iterator *it)
{
    void *data;

    if (!iterator_hasNext(it))
        return NULL;

    data = it->e->data;
    it->e = it->e->next;

    return data;
}

Element *newElement(Element *next, void *data)
{
    Element *e;

    e = (Element *)malloc(sizeof(Element));
    if (e == NULL) {
        fprintf(stderr, "%s:%d: error: %s()\n", __FILE__, __LINE__, __func__);
        return NULL;
    }

    e->next = next;
    e->data = data;

    return e;
}

void deleteElement(Element *e)
{
    free(e);
}