--- a/ChangeLog	Fri Dec 14 23:07:39 2018 +0100
+++ b/ChangeLog	Fri Dec 14 23:07:43 2018 +0100
@@ -1,5 +1,10 @@
 2018-12-14  Bruno Haible  <bruno@clisp.org>
 
+	array-map: New module.
+	* lib/gl_array_map.h: New file.
+	* lib/gl_array_map.c: New file.
+	* modules/array-map: New file.
+
 	map: New module.
 	* lib/gl_map.h: New file.
 	* lib/gl_map.c: New file.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/gl_array_map.c	Fri Dec 14 23:07:43 2018 +0100
@@ -0,0 +1,299 @@
+/* Map data type implemented by an array.
+   Copyright (C) 2006-2018 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2018.
+
+   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 3 of the License, 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, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "gl_array_map.h"
+
+#include <stdlib.h>
+
+/* Checked size_t computations.  */
+#include "xsize.h"
+
+#ifndef uintptr_t
+# define uintptr_t unsigned long
+#endif
+
+/* --------------------------- gl_map_t Data Type --------------------------- */
+
+struct pair
+{
+  const void *key;
+  const void *value;
+};
+
+/* Concrete gl_map_impl type, valid for this file only.  */
+struct gl_map_impl
+{
+  struct gl_map_impl_base base;
+  /* An array of ALLOCATED pairs, of which the first COUNT are used.
+     0 <= COUNT <= ALLOCATED.  */
+  struct pair *pairs;
+  size_t count;
+  size_t allocated;
+};
+
+static gl_map_t
+gl_array_nx_create_empty (gl_map_implementation_t implementation,
+                          gl_mapkey_equals_fn equals_fn,
+                          gl_mapkey_hashcode_fn hashcode_fn,
+                          gl_mapkey_dispose_fn kdispose_fn,
+                          gl_mapvalue_dispose_fn vdispose_fn)
+{
+  struct gl_map_impl *map =
+    (struct gl_map_impl *) malloc (sizeof (struct gl_map_impl));
+
+  if (map == NULL)
+    return NULL;
+
+  map->base.vtable = implementation;
+  map->base.equals_fn = equals_fn;
+  map->base.kdispose_fn = kdispose_fn;
+  map->base.vdispose_fn = vdispose_fn;
+  map->pairs = NULL;
+  map->count = 0;
+  map->allocated = 0;
+
+  return map;
+}
+
+static size_t
+gl_array_size (gl_map_t map)
+{
+  return map->count;
+}
+
+static size_t
+gl_array_indexof (gl_map_t map, const void *key)
+{
+  size_t count = map->count;
+
+  if (count > 0)
+    {
+      gl_mapkey_equals_fn equals = map->base.equals_fn;
+      if (equals != NULL)
+        {
+          size_t i;
+
+          for (i = 0; i < count; i++)
+            if (equals (map->pairs[i].key, key))
+              return i;
+        }
+      else
+        {
+          size_t i;
+
+          for (i = 0; i < count; i++)
+            if (map->pairs[i].key == key)
+              return i;
+        }
+    }
+  return (size_t)(-1);
+}
+
+static bool
+gl_array_search (gl_map_t map, const void *key, const void **valuep)
+{
+  size_t index = gl_array_indexof (map, key);
+  if (index != (size_t)(-1))
+    {
+      *valuep = map->pairs[index].value;
+      return true;
+    }
+  else
+    return false;
+}
+
+/* Ensure that map->allocated > map->count.
+   Return 0 upon success, -1 upon out-of-memory.  */
+static int
+grow (gl_map_t map)
+{
+  size_t new_allocated;
+  size_t memory_size;
+  struct pair *memory;
+
+  new_allocated = xtimes (map->allocated, 2);
+  new_allocated = xsum (new_allocated, 1);
+  memory_size = xtimes (new_allocated, sizeof (struct pair));
+  if (size_overflow_p (memory_size))
+    /* Overflow, would lead to out of memory.  */
+    return -1;
+  memory = (struct pair *) realloc (map->pairs, memory_size);
+  if (memory == NULL)
+    /* Out of memory.  */
+    return -1;
+  map->pairs = memory;
+  map->allocated = new_allocated;
+  return 0;
+}
+
+static int
+gl_array_nx_getput (gl_map_t map, const void *key, const void *value,
+                    const void **oldvaluep)
+{
+  size_t index = gl_array_indexof (map, key);
+  if (index != (size_t)(-1))
+    {
+      *oldvaluep = map->pairs[index].value;
+      map->pairs[index].value = value;
+      return 0;
+    }
+  else
+    {
+      size_t count = map->count;
+      struct pair *pairs;
+
+      if (count == map->allocated)
+        if (grow (map) < 0)
+          return -1;
+      pairs = map->pairs;
+      pairs[count].key = key;
+      pairs[count].value = value;
+      map->count = count + 1;
+      return 1;
+    }
+}
+
+/* Remove the pair at the given position,
+   0 <= position < gl_map_size (map).  */
+static void
+gl_array_remove_at (gl_map_t map, size_t position)
+{
+  size_t count = map->count;
+  struct pair *pairs;
+  size_t i;
+
+  pairs = map->pairs;
+  if (map->base.kdispose_fn != NULL)
+    map->base.kdispose_fn (pairs[position].key);
+  for (i = position + 1; i < count; i++)
+    pairs[i - 1] = pairs[i];
+  map->count = count - 1;
+}
+
+static bool
+gl_array_getremove (gl_map_t map, const void *key, const void **oldvaluep)
+{
+  size_t index = gl_array_indexof (map, key);
+  if (index != (size_t)(-1))
+    {
+      *oldvaluep = map->pairs[index].value;
+      gl_array_remove_at (map, index);
+      return true;
+    }
+  else
+    return false;
+}
+
+static void
+gl_array_free (gl_map_t map)
+{
+  if (map->pairs != NULL)
+    {
+      if (map->base.kdispose_fn != NULL || map->base.vdispose_fn != NULL)
+        {
+          size_t count = map->count;
+
+          if (count > 0)
+            {
+              gl_mapkey_dispose_fn kdispose = map->base.kdispose_fn;
+              gl_mapvalue_dispose_fn vdispose = map->base.vdispose_fn;
+              struct pair *pairs = map->pairs;
+
+              do
+                {
+                  if (vdispose)
+                    vdispose (pairs->value);
+                  if (kdispose)
+                    kdispose (pairs->key);
+                  pairs++;
+                }
+              while (--count > 0);
+            }
+        }
+      free (map->pairs);
+    }
+  free (map);
+}
+
+/* ---------------------- gl_map_iterator_t Data Type ---------------------- */
+
+static gl_map_iterator_t
+gl_array_iterator (gl_map_t map)
+{
+  gl_map_iterator_t result;
+
+  result.vtable = map->base.vtable;
+  result.map = map;
+  result.count = map->count;
+  result.p = map->pairs + 0;
+  result.q = map->pairs + map->count;
+#if defined GCC_LINT || defined lint
+  result.i = 0;
+  result.j = 0;
+#endif
+
+  return result;
+}
+
+static bool
+gl_array_iterator_next (gl_map_iterator_t *iterator,
+                        const void **keyp, const void **valuep)
+{
+  gl_map_t map = iterator->map;
+  if (iterator->count != map->count)
+    {
+      if (iterator->count != map->count + 1)
+        /* Concurrent modifications were done on the map.  */
+        abort ();
+      /* The last returned pair was removed.  */
+      iterator->count--;
+      iterator->p = (struct pair *) iterator->p - 1;
+      iterator->q = (struct pair *) iterator->q - 1;
+    }
+  if (iterator->p < iterator->q)
+    {
+      struct pair *p = (struct pair *) iterator->p;
+      *keyp = p->key;
+      *valuep = p->value;
+      iterator->p = p + 1;
+      return true;
+    }
+  else
+    return false;
+}
+
+static void
+gl_array_iterator_free (gl_map_iterator_t *iterator)
+{
+}
+
+
+const struct gl_map_implementation gl_array_map_implementation =
+  {
+    gl_array_nx_create_empty,
+    gl_array_size,
+    gl_array_search,
+    gl_array_nx_getput,
+    gl_array_getremove,
+    gl_array_free,
+    gl_array_iterator,
+    gl_array_iterator_next,
+    gl_array_iterator_free
+  };

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/gl_array_map.h	Fri Dec 14 23:07:43 2018 +0100
@@ -0,0 +1,34 @@
+/* Map data type implemented by an array.
+   Copyright (C) 2006, 2009-2018 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2018.
+
+   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 3 of the License, 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, see <https://www.gnu.org/licenses/>.  */
+
+#ifndef _GL_ARRAY_MAP_H
+#define _GL_ARRAY_MAP_H
+
+#include "gl_map.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern const struct gl_map_implementation gl_array_map_implementation;
+#define GL_ARRAY_MAP &gl_array_map_implementation
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _GL_ARRAY_MAP_H */

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/modules/array-map	Fri Dec 14 23:07:43 2018 +0100
@@ -0,0 +1,24 @@
+Description:
+Set data type implemented by an array.
+
+Files:
+lib/gl_array_map.h
+lib/gl_array_map.c
+
+Depends-on:
+map
+xsize
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += gl_array_map.h gl_array_map.c
+
+Include:
+"gl_array_map.h"
+
+License:
+GPL
+
+Maintainer:
+all