changeset 6979:17657e80a184

Sequential list data type implemented by a hash table with a linked list.
author Bruno Haible <bruno@clisp.org>
date Mon, 17 Jul 2006 11:30:30 +0000
parents ec26419f7c0b
children 9ccb96800d02
files lib/gl_linkedhash_list.c lib/gl_linkedhash_list.h modules/linkedhash-list modules/linkedhash-list-tests tests/test-linkedhash_list.c
diffstat 5 files changed, 618 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
new file mode 100644
--- /dev/null
+++ b/lib/gl_linkedhash_list.c
@@ -0,0 +1,123 @@
+/* Sequential list data type implemented by a hash table with a linked list.
+   Copyright (C) 2006 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2006.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+/* Specification.  */
+#include "gl_linked_list.h"
+
+#include <stdlib.h>
+
+#include "xalloc.h"
+#include "xsize.h"
+#include "size_max.h"
+
+#ifndef uintptr_t
+# define uintptr_t unsigned long
+#endif
+
+#define WITH_HASHTABLE 1
+
+/* -------------------------- gl_list_t Data Type -------------------------- */
+
+/* Generic hash-table code.  */
+#include "gl_anyhash_list1.h"
+
+/* Generic linked list code.  */
+#include "gl_anylinked_list1.h"
+
+/* Generic hash-table code.  */
+#include "gl_anyhash_list2.h"
+
+/* Resize the hash table if needed, after list->count was incremented.  */
+static inline void
+hash_resize_after_add (gl_list_t list)
+{
+  size_t count = list->count;
+  size_t estimate = xsum (count, count / 2); /* 1.5 * count */
+  if (estimate > list->table_size)
+    hash_resize (list, estimate);
+}
+
+/* Add a node to the hash table structure.  */
+static inline void
+add_to_bucket (gl_list_t list, gl_list_node_t node)
+{
+  size_t index = node->h.hashcode % list->table_size;
+
+  node->h.hash_next = list->table[index];
+  list->table[index] = &node->h;
+}
+
+/* Remove a node from the hash table structure.  */
+static inline void
+remove_from_bucket (gl_list_t list, gl_list_node_t node)
+{
+  size_t index = node->h.hashcode % list->table_size;
+  gl_hash_entry_t *p;
+
+  for (p = &list->table[index]; ; p = &(*p)->hash_next)
+    {
+      if (*p == &node->h)
+	{
+	  *p = node->h.hash_next;
+	  break;
+	}
+      if (*p == NULL)
+	/* node is not in the right bucket.  Did the hash codes
+	   change inadvertently?  */
+	abort ();
+    }
+}
+
+/* Generic linked list code.  */
+#include "gl_anylinked_list2.h"
+
+
+const struct gl_list_implementation gl_linkedhash_list_implementation =
+  {
+    gl_linked_create_empty,
+    gl_linked_create,
+    gl_linked_size,
+    gl_linked_node_value,
+    gl_linked_next_node,
+    gl_linked_previous_node,
+    gl_linked_get_at,
+    gl_linked_set_at,
+    gl_linked_search,
+    gl_linked_indexof,
+    gl_linked_add_first,
+    gl_linked_add_last,
+    gl_linked_add_before,
+    gl_linked_add_after,
+    gl_linked_add_at,
+    gl_linked_remove_node,
+    gl_linked_remove_at,
+    gl_linked_remove,
+    gl_linked_list_free,
+    gl_linked_iterator,
+    gl_linked_iterator_from_to,
+    gl_linked_iterator_next,
+    gl_linked_iterator_free,
+    gl_linked_sortedlist_search,
+    gl_linked_sortedlist_indexof,
+    gl_linked_sortedlist_add,
+    gl_linked_sortedlist_remove
+  };
new file mode 100644
--- /dev/null
+++ b/lib/gl_linkedhash_list.h
@@ -0,0 +1,35 @@
+/* Sequential list data type implemented by a hash table with a linked list.
+   Copyright (C) 2006 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2006.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#ifndef _GL_LINKEDHASH_LIST_H
+#define _GL_LINKEDHASH_LIST_H
+
+#include "gl_list.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern const struct gl_list_implementation gl_linkedhash_list_implementation;
+#define GL_LINKEDHASH_LIST &gl_linkedhash_list_implementation
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _GL_LINKEDHASH_LIST_H */
new file mode 100644
--- /dev/null
+++ b/modules/linkedhash-list
@@ -0,0 +1,31 @@
+Description:
+Sequential list data type implemented by a hash table with a linked list.
+
+Files:
+lib/gl_linkedhash_list.h
+lib/gl_linkedhash_list.c
+lib/gl_anyhash_list1.h
+lib/gl_anyhash_list2.h
+lib/gl_anylinked_list1.h
+lib/gl_anylinked_list2.h
+
+Depends-on:
+list
+size_max
+xalloc
+xsize
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += gl_linkedhash_list.h gl_linkedhash_list.c gl_anyhash_list1.h gl_anyhash_list2.h gl_anylinked_list1.h gl_anylinked_list2.h
+
+Include:
+"gl_linkedhash_list.h"
+
+License:
+GPL
+
+Maintainer:
+Bruno Haible
+
new file mode 100644
--- /dev/null
+++ b/modules/linkedhash-list-tests
@@ -0,0 +1,12 @@
+Files:
+tests/test-linkedhash_list.c
+
+Depends-on:
+array-list
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-linkedhash_list$(EXEEXT)
+check_PROGRAMS += test-linkedhash_list
+
new file mode 100644
--- /dev/null
+++ b/tests/test-linkedhash_list.c
@@ -0,0 +1,417 @@
+/* Test of sequential list data type implementation.
+   Copyright (C) 2006 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2006.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "gl_array_list.h"
+#include "gl_linkedhash_list.h"
+
+static const char *objects[15] =
+  {
+    "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o"
+  };
+
+#define SIZE_BITS (sizeof (size_t) * CHAR_BIT)
+
+static bool
+string_equals (const void *x1, const void *x2)
+{
+  const char *s1 = x1;
+  const char *s2 = x2;
+  return strcmp (s1, s2) == 0;
+}
+
+/* A hash function for NUL-terminated char* strings using
+   the method described by Bruno Haible.
+   See http://www.haible.de/bruno/hashfunc.html.  */
+static size_t
+string_hash (const void *x)
+{
+  const char *s = x;
+  size_t h = 0;
+
+  for (; *s; s++)
+    h = *s + ((h << 9) | (h >> (SIZE_BITS - 9)));
+
+  return h;
+}
+
+#define SIZEOF(array) (sizeof (array) / sizeof (array[0]))
+#define ASSERT(condition) if (!(condition)) abort ()
+#define RANDOM(n) (rand () % (n))
+#define RANDOM_OBJECT() objects[RANDOM (SIZEOF (objects))]
+
+static void
+check_equals (gl_list_t list1, gl_list_t list2)
+{
+  size_t n, i;
+
+  n = gl_list_size (list1);
+  ASSERT (n == gl_list_size (list2));
+  for (i = 0; i < n; i++)
+    {
+      ASSERT (gl_list_get_at (list1, i) == gl_list_get_at (list2, i));
+    }
+}
+
+static void
+check_all (gl_list_t list1, gl_list_t list2, gl_list_t list3)
+{
+  check_equals (list1, list2);
+  check_equals (list1, list3);
+}
+
+int
+main (int argc, char *argv[])
+{
+  gl_list_t list1, list2, list3;
+
+  /* Allow the user to provide a non-default random seed on the command line.  */
+  if (argc > 1)
+    srand (atoi (argv[1]));
+
+  {
+    size_t initial_size = RANDOM (50);
+    const void **contents =
+      (const void **) malloc (initial_size * sizeof (const void *));
+    size_t i;
+    unsigned int repeat;
+
+    for (i = 0; i < initial_size; i++)
+      contents[i] = RANDOM_OBJECT ();
+
+    /* Create list1.  */
+    list1 = gl_list_create (GL_ARRAY_LIST,
+                            string_equals, string_hash, true,
+                            initial_size, contents);
+    /* Create list2.  */
+    list2 = gl_list_create_empty (GL_LINKEDHASH_LIST,
+                                  string_equals, string_hash, true);
+    for (i = 0; i < initial_size; i++)
+      gl_list_add_last (list2, contents[i]);
+
+    /* Create list3.  */
+    list3 = gl_list_create (GL_LINKEDHASH_LIST,
+                            string_equals, string_hash, true,
+                            initial_size, contents);
+
+    check_all (list1, list2, list3);
+
+    for (repeat = 0; repeat < 10000; repeat++)
+      {
+        unsigned int operation = RANDOM (16);
+        switch (operation)
+          {
+          case 0:
+            if (gl_list_size (list1) > 0)
+              {
+                size_t index = RANDOM (gl_list_size (list1));
+                const char *obj = RANDOM_OBJECT ();
+                gl_list_node_t node1, node2, node3;
+
+                node1 = gl_list_set_at (list1, index, obj);
+                ASSERT (gl_list_get_at (list1, index) == obj);
+                ASSERT (gl_list_node_value (list1, node1) == obj);
+
+                node2 = gl_list_set_at (list2, index, obj);
+                ASSERT (gl_list_get_at (list2, index) == obj);
+                ASSERT (gl_list_node_value (list2, node2) == obj);
+
+                node3 = gl_list_set_at (list3, index, obj);
+                ASSERT (gl_list_get_at (list3, index) == obj);
+                ASSERT (gl_list_node_value (list3, node3) == obj);
+
+                if (index > 0)
+                  {
+                    ASSERT (gl_list_node_value (list1, gl_list_previous_node (list1, node1))
+                            == gl_list_get_at (list1, index - 1));
+                    ASSERT (gl_list_node_value (list2, gl_list_previous_node (list3, node3))
+                            == gl_list_get_at (list2, index - 1));
+                    ASSERT (gl_list_node_value (list3, gl_list_previous_node (list3, node3))
+                            == gl_list_get_at (list2, index - 1));
+                  }
+                if (index + 1 < gl_list_size (list1))
+                  {
+                    ASSERT (gl_list_node_value (list1, gl_list_next_node (list1, node1))
+                            == gl_list_get_at (list1, index + 1));
+                    ASSERT (gl_list_node_value (list2, gl_list_next_node (list3, node3))
+                            == gl_list_get_at (list2, index + 1));
+                    ASSERT (gl_list_node_value (list3, gl_list_next_node (list3, node3))
+                            == gl_list_get_at (list2, index + 1));
+                  }
+              }
+            break;
+          case 1:
+            {
+              const char *obj = RANDOM_OBJECT ();
+              gl_list_node_t node1, node2, node3;
+              node1 = gl_list_search (list1, obj);
+              node2 = gl_list_search (list2, obj);
+              node3 = gl_list_search (list3, obj);
+              if (node1 == NULL)
+                {
+                  ASSERT (node2 == NULL);
+                  ASSERT (node3 == NULL);
+                }
+              else
+                {
+                  ASSERT (node2 != NULL);
+                  ASSERT (node3 != NULL);
+                  ASSERT (gl_list_node_value (list1, node1) == obj);
+                  ASSERT (gl_list_node_value (list2, node2) == obj);
+                  ASSERT (gl_list_node_value (list3, node3) == obj);
+                }
+            }
+            break;
+          case 2:
+            {
+              const char *obj = RANDOM_OBJECT ();
+              size_t index1, index2, index3;
+              index1 = gl_list_indexof (list1, obj);
+              index2 = gl_list_indexof (list2, obj);
+              index3 = gl_list_indexof (list3, obj);
+              if (index1 == (size_t)(-1))
+                {
+                  ASSERT (index2 == (size_t)(-1));
+                  ASSERT (index3 == (size_t)(-1));
+                }
+              else
+                {
+                  ASSERT (index2 != (size_t)(-1));
+                  ASSERT (index3 != (size_t)(-1));
+                  ASSERT (gl_list_get_at (list1, index1) == obj);
+                  ASSERT (gl_list_get_at (list2, index2) == obj);
+                  ASSERT (gl_list_get_at (list3, index3) == obj);
+                  ASSERT (index2 == index1);
+                  ASSERT (index3 == index1);
+                }
+            }
+            break;
+          case 3: /* add 1 element */
+            {
+              const char *obj = RANDOM_OBJECT ();
+              gl_list_node_t node1, node2, node3;
+              node1 = gl_list_add_first (list1, obj);
+              node2 = gl_list_add_first (list2, obj);
+              node3 = gl_list_add_first (list3, obj);
+              ASSERT (gl_list_node_value (list1, node1) == obj);
+              ASSERT (gl_list_node_value (list2, node2) == obj);
+              ASSERT (gl_list_node_value (list3, node3) == obj);
+              ASSERT (gl_list_get_at (list1, 0) == obj);
+              ASSERT (gl_list_get_at (list2, 0) == obj);
+              ASSERT (gl_list_get_at (list3, 0) == obj);
+            }
+            break;
+          case 4: /* add 1 element */
+            {
+              const char *obj = RANDOM_OBJECT ();
+              gl_list_node_t node1, node2, node3;
+              node1 = gl_list_add_last (list1, obj);
+              node2 = gl_list_add_last (list2, obj);
+              node3 = gl_list_add_last (list3, obj);
+              ASSERT (gl_list_node_value (list1, node1) == obj);
+              ASSERT (gl_list_node_value (list2, node2) == obj);
+              ASSERT (gl_list_node_value (list3, node3) == obj);
+              ASSERT (gl_list_get_at (list1, gl_list_size (list1) - 1) == obj);
+              ASSERT (gl_list_get_at (list2, gl_list_size (list2) - 1) == obj);
+              ASSERT (gl_list_get_at (list3, gl_list_size (list3) - 1) == obj);
+            }
+            break;
+          case 5: /* add 3 elements */
+            {
+              const char *obj0 = RANDOM_OBJECT ();
+              const char *obj1 = RANDOM_OBJECT ();
+              const char *obj2 = RANDOM_OBJECT ();
+              gl_list_node_t node1, node2, node3;
+              node1 = gl_list_add_first (list1, obj2);
+              node1 = gl_list_add_before (list1, node1, obj0);
+              node1 = gl_list_add_after (list1, node1, obj1);
+              node2 = gl_list_add_first (list2, obj2);
+              node2 = gl_list_add_before (list2, node2, obj0);
+              node2 = gl_list_add_after (list2, node2, obj1);
+              node3 = gl_list_add_first (list3, obj2);
+              node3 = gl_list_add_before (list3, node3, obj0);
+              node3 = gl_list_add_after (list3, node3, obj1);
+              ASSERT (gl_list_node_value (list1, node1) == obj1);
+              ASSERT (gl_list_node_value (list2, node2) == obj1);
+              ASSERT (gl_list_node_value (list3, node3) == obj1);
+              ASSERT (gl_list_get_at (list1, 0) == obj0);
+              ASSERT (gl_list_get_at (list1, 1) == obj1);
+              ASSERT (gl_list_get_at (list1, 2) == obj2);
+              ASSERT (gl_list_get_at (list2, 0) == obj0);
+              ASSERT (gl_list_get_at (list2, 1) == obj1);
+              ASSERT (gl_list_get_at (list2, 2) == obj2);
+              ASSERT (gl_list_get_at (list3, 0) == obj0);
+              ASSERT (gl_list_get_at (list3, 1) == obj1);
+              ASSERT (gl_list_get_at (list3, 2) == obj2);
+            }
+            break;
+          case 6: /* add 1 element */
+            {
+              size_t index = RANDOM (gl_list_size (list1) + 1);
+              const char *obj = RANDOM_OBJECT ();
+              gl_list_node_t node1, node2, node3;
+              node1 = gl_list_add_at (list1, index, obj);
+              node2 = gl_list_add_at (list2, index, obj);
+              node3 = gl_list_add_at (list3, index, obj);
+              ASSERT (gl_list_get_at (list1, index) == obj);
+              ASSERT (gl_list_node_value (list1, node1) == obj);
+              ASSERT (gl_list_get_at (list2, index) == obj);
+              ASSERT (gl_list_node_value (list2, node2) == obj);
+              ASSERT (gl_list_get_at (list3, index) == obj);
+              ASSERT (gl_list_node_value (list3, node3) == obj);
+              if (index > 0)
+                {
+                  ASSERT (gl_list_node_value (list1, gl_list_previous_node (list1, node1))
+                          == gl_list_get_at (list1, index - 1));
+                  ASSERT (gl_list_node_value (list2, gl_list_previous_node (list3, node3))
+                          == gl_list_get_at (list2, index - 1));
+                  ASSERT (gl_list_node_value (list3, gl_list_previous_node (list3, node3))
+                          == gl_list_get_at (list2, index - 1));
+                }
+              if (index + 1 < gl_list_size (list1))
+                {
+                  ASSERT (gl_list_node_value (list1, gl_list_next_node (list1, node1))
+                          == gl_list_get_at (list1, index + 1));
+                  ASSERT (gl_list_node_value (list2, gl_list_next_node (list3, node3))
+                          == gl_list_get_at (list2, index + 1));
+                  ASSERT (gl_list_node_value (list3, gl_list_next_node (list3, node3))
+                          == gl_list_get_at (list2, index + 1));
+                }
+            }
+            break;
+          case 7: case 8: /* remove 1 element */
+            if (gl_list_size (list1) > 0)
+              {
+                size_t n = gl_list_size (list1);
+                const char *obj = gl_list_get_at (list1, RANDOM (n));
+                gl_list_node_t node1, node2, node3;
+                node1 = gl_list_search (list1, obj);
+                node2 = gl_list_search (list2, obj);
+                node3 = gl_list_search (list3, obj);
+                ASSERT (node1 != NULL);
+                ASSERT (node2 != NULL);
+                ASSERT (node3 != NULL);
+                ASSERT (gl_list_remove_node (list1, node1));
+                ASSERT (gl_list_remove_node (list2, node2));
+                ASSERT (gl_list_remove_node (list3, node3));
+                ASSERT (gl_list_size (list1) == n - 1);
+              }
+            break;
+          case 9: case 10: /* remove 1 element */
+            if (gl_list_size (list1) > 0)
+              {
+                size_t n = gl_list_size (list1);
+                size_t index = RANDOM (n);
+                ASSERT (gl_list_remove_at (list1, index));
+                ASSERT (gl_list_remove_at (list2, index));
+                ASSERT (gl_list_remove_at (list3, index));
+                ASSERT (gl_list_size (list1) == n - 1);
+              }
+            break;
+          case 11: case 12: /* remove 1 element */
+            if (gl_list_size (list1) > 0)
+              {
+                size_t n = gl_list_size (list1);
+                const char *obj = gl_list_get_at (list1, RANDOM (n));
+                ASSERT (gl_list_remove (list1, obj));
+                ASSERT (gl_list_remove (list2, obj));
+                ASSERT (gl_list_remove (list3, obj));
+                ASSERT (gl_list_size (list1) == n - 1);
+              }
+            break;
+          case 13:
+            if (gl_list_size (list1) > 0)
+              {
+                size_t n = gl_list_size (list1);
+                const char *obj = "xyzzy";
+                ASSERT (!gl_list_remove (list1, obj));
+                ASSERT (!gl_list_remove (list2, obj));
+                ASSERT (!gl_list_remove (list3, obj));
+                ASSERT (gl_list_size (list1) == n);
+              }
+            break;
+          case 14:
+            {
+              size_t n = gl_list_size (list1);
+              gl_list_iterator_t iter1, iter2, iter3;
+              const void *elt;
+              iter1 = gl_list_iterator (list1);
+              iter2 = gl_list_iterator (list2);
+              iter3 = gl_list_iterator (list3);
+              for (i = 0; i < n; i++)
+                {
+                  ASSERT (gl_list_iterator_next (&iter1, &elt, NULL));
+                  ASSERT (gl_list_get_at (list1, i) == elt);
+                  ASSERT (gl_list_iterator_next (&iter2, &elt, NULL));
+                  ASSERT (gl_list_get_at (list2, i) == elt);
+                  ASSERT (gl_list_iterator_next (&iter3, &elt, NULL));
+                  ASSERT (gl_list_get_at (list3, i) == elt);
+                }
+              ASSERT (!gl_list_iterator_next (&iter1, &elt, NULL));
+              ASSERT (!gl_list_iterator_next (&iter2, &elt, NULL));
+              ASSERT (!gl_list_iterator_next (&iter3, &elt, NULL));
+              gl_list_iterator_free (&iter1);
+              gl_list_iterator_free (&iter2);
+              gl_list_iterator_free (&iter3);
+            }
+            break;
+          case 15:
+            {
+              size_t end = RANDOM (gl_list_size (list1) + 1);
+              size_t start = RANDOM (end + 1);
+              gl_list_iterator_t iter1, iter2, iter3;
+              const void *elt;
+              iter1 = gl_list_iterator_from_to (list1, start, end);
+              iter2 = gl_list_iterator_from_to (list2, start, end);
+              iter3 = gl_list_iterator_from_to (list3, start, end);
+              for (i = start; i < end; i++)
+                {
+                  ASSERT (gl_list_iterator_next (&iter1, &elt, NULL));
+                  ASSERT (gl_list_get_at (list1, i) == elt);
+                  ASSERT (gl_list_iterator_next (&iter2, &elt, NULL));
+                  ASSERT (gl_list_get_at (list2, i) == elt);
+                  ASSERT (gl_list_iterator_next (&iter3, &elt, NULL));
+                  ASSERT (gl_list_get_at (list3, i) == elt);
+                }
+              ASSERT (!gl_list_iterator_next (&iter1, &elt, NULL));
+              ASSERT (!gl_list_iterator_next (&iter2, &elt, NULL));
+              ASSERT (!gl_list_iterator_next (&iter3, &elt, NULL));
+              gl_list_iterator_free (&iter1);
+              gl_list_iterator_free (&iter2);
+              gl_list_iterator_free (&iter3);
+            }
+            break;
+          }
+        check_all (list1, list2, list3);
+      }
+
+    gl_list_free (list1);
+    gl_list_free (list2);
+    gl_list_free (list3);
+    free (contents);
+  }
+
+  return 0;
+}