itersample.c

迭代器算法

/* itersample.c --- demonstrate the usage of iterator */
#include <stdlib.h>
#include <stdio.h>

#define STRV_NUMBER		5

typedef struct _StringList
{
	char *str_array[STRV_NUMBER];
} StringList;

typedef struct _StringListIter StringListIter;

typedef char* (*StringListIterGetStrFunc)(StringListIter* iter);
typedef void  (*StringListIterNextFunc)(StringListIter* iter);
typedef int   (*StringListIterIsDoneFunc)(StringListIter* iter);

typedef struct _StringListIterInterface
{
	StringListIterGetStrFunc  iter_get_str;
	StringListIterNextFunc    iter_next;
	StringListIterIsDoneFunc  iter_is_done;
} StringListIterInterface;

struct _StringListIter
{
	StringListIterInterface	iface;
	StringList*				str_list;
	int						index;
};

typedef struct _StringListNormIter
{
	StringListIter  parent;
} StringListNormIter;

typedef struct _StringListRevIter
{
	StringListIter  parent;
} StringListRevIter;

static StringList static_string_list =
{
	.str_array = {"aaa", "bbb", "ccc", "ddd", "eee"}
};

StringList* string_list_new(void)
{
	return &static_string_list;
}

static char* string_list_norm_iter_get_str (StringListIter* iter)
{
	StringListNormIter* norm_iter;

	norm_iter = (StringListNormIter*)iter;
	return norm_iter->parent.str_list->str_array[iter->index];
}

static void string_list_norm_iter_next (StringListIter* iter)
{
	StringListNormIter* norm_iter;

	norm_iter = (StringListNormIter*)iter;
	norm_iter->parent.index++;
}

static int string_list_norm_iter_is_done (StringListIter* iter)
{
	StringListNormIter* norm_iter;

	norm_iter = (StringListNormIter*)iter;
	return norm_iter->parent.index >= STRV_NUMBER;
}

static char* string_list_rev_iter_get_str (StringListIter* iter)
{
	StringListRevIter* rev_iter;

	rev_iter = (StringListRevIter*)iter;
	return rev_iter->parent.str_list->str_array[iter->index];
}

static void string_list_rev_iter_next (StringListIter* iter)
{
	StringListRevIter* rev_iter;

	rev_iter = (StringListRevIter*)iter;
	rev_iter->parent.index--;
}

static int string_list_rev_iter_is_done (StringListIter* iter)
{
	StringListRevIter* rev_iter;

	rev_iter = (StringListRevIter*)iter;
	return rev_iter->parent.index < 0;
}

char* string_list_iter_get_str (StringListIter* iter)
{
	return iter->iface.iter_get_str (iter);
}

void string_list_iter_next (StringListIter* iter)
{
	iter->iface.iter_next (iter);
}

int string_list_iter_is_done (StringListIter* iter)
{
	return iter->iface.iter_is_done (iter);
}

StringListNormIter* string_list_get_norm_iter (StringList* list)
{
	StringListNormIter* iter;

	iter = (StringListNormIter*) malloc (sizeof (StringListNormIter));
	iter->parent.str_list = list;
	iter->parent.index = 0;
	iter->parent.iface.iter_get_str  = string_list_norm_iter_get_str;
	iter->parent.iface.iter_next	 = string_list_norm_iter_next;
	iter->parent.iface.iter_is_done  = string_list_norm_iter_is_done;
	return iter;
}

StringListRevIter* string_list_get_rev_iter (StringList* list)
{
	StringListRevIter* riter;

	riter = (StringListRevIter*) malloc (sizeof (StringListRevIter));
	riter->parent.str_list = list;
	riter->parent.index = STRV_NUMBER - 1;
	riter->parent.iface.iter_get_str = string_list_rev_iter_get_str;
	riter->parent.iface.iter_next	 = string_list_rev_iter_next;
	riter->parent.iface.iter_is_done = string_list_rev_iter_is_done;
	return riter;
}

static void list_all_string (StringListIter* iter)
{
	for (; !string_list_iter_is_done (iter); string_list_iter_next (iter))
	{
		printf ("%s\n", string_list_iter_get_str (iter));
	}
}

int main (int argc, char **argv)
{
	StringList* str_list;
	StringListNormIter* iter;
	StringListRevIter*  riter;

	str_list = string_list_new ();

	printf ("Print all string:\n");
	iter = string_list_get_norm_iter (str_list);
	list_all_string ((StringListIter*)iter);

	printf ("\nReverse print all string:\n");
	riter = string_list_get_rev_iter (str_list);
	list_all_string ((StringListIter*)riter);
}