From 57f74fa836b4ce3eac3bf0710d1cc0e7f5207e2b Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Wed, 19 Dec 2018 13:28:34 -0500
Subject: [PATCH] Initial file

---
 hashset.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 145 insertions(+)
 create mode 100644 hashset.c

diff --git a/hashset.c b/hashset.c
new file mode 100644
index 00000000..d0dcc7af
--- /dev/null
+++ b/hashset.c
@@ -0,0 +1,145 @@
+/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+/*
+ *     Copyright 2012 Couchbase, Inc.
+ *
+ *   Licensed under the Apache License, Version 2.0 (the "License");
+ *   you may not use this file except in compliance with the License.
+ *   You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *   Unless required by applicable law or agreed to in writing, software
+ *   distributed under the License is distributed on an "AS IS" BASIS,
+ *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *   See the License for the specific language governing permissions and
+ *   limitations under the License.
+ */
+
+#include "cyclone/hashset.h"
+#include <assert.h>
+
+static const unsigned int prime_1 = 73;
+static const unsigned int prime_2 = 5009;
+
+hashset_t hashset_create()
+{
+    hashset_t set = calloc(1, sizeof(struct hashset_st));
+
+    if (set == NULL) {
+        return NULL;
+    }
+    set->nbits = 3;
+    set->capacity = (size_t)(1 << set->nbits);
+    set->mask = set->capacity - 1;
+    set->items = calloc(set->capacity, sizeof(size_t));
+    if (set->items == NULL) {
+        hashset_destroy(set);
+        return NULL;
+    }
+    set->nitems = 0;
+    set->n_deleted_items = 0;
+    return set;
+}
+
+size_t hashset_num_items(hashset_t set)
+{
+    return set->nitems;
+}
+
+void hashset_destroy(hashset_t set)
+{
+    if (set) {
+        free(set->items);
+    }
+    free(set);
+}
+
+static int hashset_add_member(hashset_t set, void *item)
+{
+    size_t value = (size_t)item;
+    size_t ii;
+
+    if (value == 0 || value == 1) {
+        return -1;
+    }
+
+    ii = set->mask & (prime_1 * value);
+
+    while (set->items[ii] != 0 && set->items[ii] != 1) {
+        if (set->items[ii] == value) {
+            return 0;
+        } else {
+            /* search free slot */
+            ii = set->mask & (ii + prime_2);
+        }
+    }
+    set->nitems++;
+    if (set->items[ii] == 1) {
+        set->n_deleted_items--;
+    }
+    set->items[ii] = value;
+    return 1;
+}
+
+static void maybe_rehash(hashset_t set)
+{
+    size_t *old_items;
+    size_t old_capacity, ii;
+
+
+    if (set->nitems + set->n_deleted_items >= (double)set->capacity * 0.85) {
+        old_items = set->items;
+        old_capacity = set->capacity;
+        set->nbits++;
+        set->capacity = (size_t)(1 << set->nbits);
+        set->mask = set->capacity - 1;
+        set->items = calloc(set->capacity, sizeof(size_t));
+        set->nitems = 0;
+        set->n_deleted_items = 0;
+        assert(set->items);
+        for (ii = 0; ii < old_capacity; ii++) {
+            hashset_add_member(set, (void *)old_items[ii]);
+        }
+        free(old_items);
+    }
+}
+
+int hashset_add(hashset_t set, void *item)
+{
+    int rv = hashset_add_member(set, item);
+    maybe_rehash(set);
+    return rv;
+}
+
+int hashset_remove(hashset_t set, void *item)
+{
+    size_t value = (size_t)item;
+    size_t ii = set->mask & (prime_1 * value);
+
+    while (set->items[ii] != 0) {
+        if (set->items[ii] == value) {
+            set->items[ii] = 1;
+            set->nitems--;
+            set->n_deleted_items++;
+            return 1;
+        } else {
+            ii = set->mask & (ii + prime_2);
+        }
+    }
+    return 0;
+}
+
+int hashset_is_member(hashset_t set, void *item)
+{
+    size_t value = (size_t)item;
+    size_t ii = set->mask & (prime_1 * value);
+
+    while (set->items[ii] != 0) {
+        if (set->items[ii] == value) {
+            return 1;
+        } else {
+            ii = set->mask & (ii + prime_2);
+        }
+    }
+    return 0;
+}