Use insertion sort for small lists, new list test.

4 files changed, 105 insertions, 9 deletions

diff --git a/bench/libdimension/list.c b/bench/libdimension/list.c
index b177d47..be75aa1 100644
--- a/bench/libdimension/list.c
+++ b/bench/libdimension/list.c
@@ -61,6 +61,7 @@ main(void)
 
   for (size_t i = 0; i < count; ++i) {
     sandglass_bench_noprecache(&sandglass, dmnsn_list_push(list, &object));
+    ++object;
     printf(" %ld", sandglass.grains);
   }
   printf("\n");
diff --git a/libdimension/list.c b/libdimension/list.c
index 421a56e..3eaaa12 100644
--- a/libdimension/list.c
+++ b/libdimension/list.c
@@ -56,8 +56,8 @@ void
 dmnsn_delete_list(dmnsn_list *list)
 {
   if (list) {
-    while (list->first) {
-      dmnsn_list_remove(list, list->first);
+    while (dmnsn_list_first(list)) {
+      dmnsn_list_remove(list, dmnsn_list_first(list));
     }
     dmnsn_free(list);
   }
@@ -97,23 +97,39 @@ dmnsn_list_split(dmnsn_list *list)
 void
 dmnsn_list_sort(dmnsn_list *list, dmnsn_list_comparator_fn *comparator)
 {
-  /* Recursive merge sort */
   if (dmnsn_list_size(list) < 2) {
     return;
-  } else if (dmnsn_list_size(list) == 2) {
-    if ((*comparator)(list->last, list->first)) {
-      dmnsn_list_swap(list->first, list->last);
-    }
+  } else if (dmnsn_list_size(list) <= 16) {
+    /* Use insertion sort on small lists */
+    dmnsn_list_iterator *current = dmnsn_list_next(dmnsn_list_first(list));
+    do {
+      dmnsn_list_iterator *next = dmnsn_list_next(current);
+      dmnsn_list_iterator_remove(list, current);
+
+      dmnsn_list_iterator *i = next;
+      do {
+        dmnsn_list_iterator *prev = i ? dmnsn_list_prev(i)
+                                      : dmnsn_list_last(list);
+        if (!(*comparator)(current, prev))
+          break;
+        i = prev;
+      } while (i != dmnsn_list_first(list));
+      dmnsn_list_iterator_insert(list, i, current);
+
+      current = next;
+    } while (current);
   } else {
+    /* Recursive merge sort */
     dmnsn_list half;
     dmnsn_list_split_impl(list, &half);
     dmnsn_list_sort(list, comparator);
     dmnsn_list_sort(&half, comparator);
 
-    dmnsn_list_iterator *i = list->first, *j = half.first;
+    dmnsn_list_iterator *i = dmnsn_list_first(list);
+    dmnsn_list_iterator *j = dmnsn_list_first(&half);
     while (i || j) {
       if (!i) {
-        j->prev = list->last;
+        j->prev = dmnsn_list_last(list);
         list->last->next = j;
         list->last = half.last;
         list->length += half.length;
diff --git a/tests/libdimension/Makefile.am b/tests/libdimension/Makefile.am
index 4dbe761..651fbaa 100644
--- a/tests/libdimension/Makefile.am
+++ b/tests/libdimension/Makefile.am
@@ -22,6 +22,7 @@ INCLUDES = -I$(top_srcdir)/libdimension
 check_LTLIBRARIES = libdimension-tests.la
 check_PROGRAMS    = error-test                                                 \
                     warning-test                                               \
+                    list-test                                                  \
                     polynomial-test                                            \
                     prtree-test                                                \
                     png-test                                                   \
@@ -60,6 +61,9 @@ error_test_LDADD   = libdimension-tests.la
 warning_test_SOURCES = warning.c
 warning_test_LDADD   = libdimension-tests.la
 
+list_test_SOURCES = list.c
+list_test_LDADD   = libdimension-tests.la
+
 polynomial_test_SOURCES = polynomial.c
 polynomial_test_LDADD   = libdimension-tests.la
 
diff --git a/tests/libdimension/list.c b/tests/libdimension/list.c
new file mode 100644
index 0000000..6a98fda
--- /dev/null
+++ b/tests/libdimension/list.c
@@ -0,0 +1,75 @@
+/*************************************************************************
+ * Copyright (C) 2010 Tavian Barnes <tavianator@gmail.com>               *
+ *                                                                       *
+ * This file is part of The Dimension Test Suite.                        *
+ *                                                                       *
+ * The Dimension Test Suite 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.                       *
+ *                                                                       *
+ * The Dimension Test Suite 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 <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+/*
+ * Basic tests of linked lists
+ */
+
+#include "dimension.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct dmnsn_item {
+  int value;
+  size_t seq;
+} dmnsn_item;
+
+static bool
+dmnsn_comparator(const dmnsn_list_iterator *i, const dmnsn_list_iterator *j)
+{
+  dmnsn_item *a = dmnsn_list_at(i), *b = dmnsn_list_at(j);
+  return a->value < b->value;
+}
+
+int
+main()
+{
+  dmnsn_list *list = dmnsn_new_list(sizeof(dmnsn_item));
+
+  /* Fill up the list with random numbers */
+  srand(1);
+  const size_t list_size = 10000;
+  for (size_t i = 0; i < list_size; ++i) {
+    dmnsn_item item;
+    item.value = rand()%(list_size/10);
+    item.seq = i;
+    dmnsn_list_push(list, &item);
+  }
+
+  /* Ensure that sorting works */
+  dmnsn_list_sort(list, &dmnsn_comparator);
+  for (dmnsn_list_iterator *i = dmnsn_list_first(list);
+       i != dmnsn_list_last(list);
+       i = dmnsn_list_next(i))
+  {
+    dmnsn_item *a = dmnsn_list_at(i), *b = dmnsn_list_at(dmnsn_list_next(i));
+    if (a->value > b->value) {
+      fprintf(stderr, "--- Sorting failed (%d > %d)! ---\n",
+              a->value, b->value);
+      return EXIT_FAILURE;
+    } else if (a->value == b->value && a->seq > b->seq) {
+      fprintf(stderr, "--- Sorting was unstable (%zu > %zu)! ---\n",
+              a->seq, b->seq);
+      return EXIT_FAILURE;
+    }
+  }
+
+  dmnsn_delete_list(list);
+  return EXIT_SUCCESS;
+}