From 0850af33e201aff596520a937b84d4b4e233668f Mon Sep 17 00:00:00 2001
From: Bailey Thompson <bkthomps@edu.uwaterloo.ca>
Date: Tue, 12 Dec 2017 20:05:05 -0500
Subject: [PATCH] Clear should cause memory size to shrink

Calling clear on an unordered (multi) set or map not only clears all elements but reduces the hash table size.
---
 src/unordered_map.c      | 13 ++++++++++++-
 src/unordered_map.h      |  2 +-
 src/unordered_multiset.c | 13 ++++++++++++-
 src/unordered_multiset.h |  2 +-
 src/unordered_set.c      | 13 ++++++++++++-
 src/unordered_set.h      |  2 +-
 6 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/src/unordered_map.c b/src/unordered_map.c
index 724d402..6a9a4aa 100644
--- a/src/unordered_map.c
+++ b/src/unordered_map.c
@@ -350,8 +350,11 @@ bool unordered_map_remove(unordered_map me, void *const key)
  * Clears the elements from the unordered map.
  *
  * @param me The unordered map to clear.
+ *
+ * @return 0       No error.
+ *         -ENOMEM Out of memory.
  */
-void unordered_map_clear(unordered_map me)
+int unordered_map_clear(unordered_map me)
 {
     for (int i = 0; i < me->capacity; i++) {
         struct node *traverse = me->buckets[i];
@@ -365,6 +368,14 @@ void unordered_map_clear(unordered_map me)
         me->buckets[i] = NULL;
     }
     me->size = 0;
+    me->capacity = STARTING_BUCKETS;
+    struct node **temp = calloc((size_t) me->capacity, sizeof(struct node *));
+    if (temp == NULL) {
+        return -ENOMEM;
+    }
+    free(me->buckets);
+    me->buckets = temp;
+    return 0;
 }
 
 /**
diff --git a/src/unordered_map.h b/src/unordered_map.h
index 857b250..610608a 100644
--- a/src/unordered_map.h
+++ b/src/unordered_map.h
@@ -46,7 +46,7 @@ bool unordered_map_contains(unordered_map me, void *key);
 bool unordered_map_remove(unordered_map me, void *key);
 
 // Ending
-void unordered_map_clear(unordered_map me);
+int unordered_map_clear(unordered_map me);
 unordered_map unordered_map_destroy(unordered_map me);
 
 #endif /* CONTAINERS_UNORDERED_MAP_H */
diff --git a/src/unordered_multiset.c b/src/unordered_multiset.c
index cb10644..e5a9051 100644
--- a/src/unordered_multiset.c
+++ b/src/unordered_multiset.c
@@ -346,8 +346,11 @@ bool unordered_multiset_remove(unordered_multiset me, void *const key)
  * Clears the elements from the unordered multi-set.
  *
  * @param me The unordered multi-set to clear.
+ *
+ * @return 0       No error.
+ *         -ENOMEM Out of memory.
  */
-void unordered_multiset_clear(unordered_multiset me)
+int unordered_multiset_clear(unordered_multiset me)
 {
     for (int i = 0; i < me->capacity; i++) {
         struct node *traverse = me->buckets[i];
@@ -361,6 +364,14 @@ void unordered_multiset_clear(unordered_multiset me)
     }
     me->size = 0;
     me->used = 0;
+    me->capacity = STARTING_BUCKETS;
+    struct node **temp = calloc((size_t) me->capacity, sizeof(struct node *));
+    if (temp == NULL) {
+        return -ENOMEM;
+    }
+    free(me->buckets);
+    me->buckets = temp;
+    return 0;
 }
 
 /**
diff --git a/src/unordered_multiset.h b/src/unordered_multiset.h
index ae920ce..92b3b53 100644
--- a/src/unordered_multiset.h
+++ b/src/unordered_multiset.h
@@ -46,7 +46,7 @@ bool unordered_multiset_contains(unordered_multiset me, void *key);
 bool unordered_multiset_remove(unordered_multiset me, void *key);
 
 // Ending
-void unordered_multiset_clear(unordered_multiset me);
+int unordered_multiset_clear(unordered_multiset me);
 unordered_multiset unordered_multiset_destroy(unordered_multiset me);
 
 #endif /* CONTAINERS_UNORDERED_MULTISET_H */
diff --git a/src/unordered_set.c b/src/unordered_set.c
index 3172d1c..80b6ee2 100644
--- a/src/unordered_set.c
+++ b/src/unordered_set.c
@@ -313,8 +313,11 @@ bool unordered_set_remove(unordered_set me, void *const key)
  * Clears the elements from the unordered set.
  *
  * @param me The unordered set to clear.
+ *
+ * @return 0       No error.
+ *         -ENOMEM Out of memory.
  */
-void unordered_set_clear(unordered_set me)
+int unordered_set_clear(unordered_set me)
 {
     for (int i = 0; i < me->capacity; i++) {
         struct node *traverse = me->buckets[i];
@@ -327,6 +330,14 @@ void unordered_set_clear(unordered_set me)
         me->buckets[i] = NULL;
     }
     me->size = 0;
+    me->capacity = STARTING_BUCKETS;
+    struct node **temp = calloc((size_t) me->capacity, sizeof(struct node *));
+    if (temp == NULL) {
+        return -ENOMEM;
+    }
+    free(me->buckets);
+    me->buckets = temp;
+    return 0;
 }
 
 /**
diff --git a/src/unordered_set.h b/src/unordered_set.h
index 330ba20..eb9dcff 100644
--- a/src/unordered_set.h
+++ b/src/unordered_set.h
@@ -44,7 +44,7 @@ bool unordered_set_contains(unordered_set me, void *key);
 bool unordered_set_remove(unordered_set me, void *key);
 
 // Ending
-void unordered_set_clear(unordered_set me);
+int unordered_set_clear(unordered_set me);
 unordered_set unordered_set_destroy(unordered_set me);
 
 #endif /* CONTAINERS_UNORDERED_SET_H */