util/IntrusiveHashSet: new class

Incomplete draft implementation, just enough methods for current
needs.

test/util/TestIntrusiveHashSet.cxx

@@ -0,0 +1,144 @@
+/*
+ * Copyright 2022 Max Kellermann <max.kellermann@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "util/IntrusiveHashSet.hxx"
+
+#include <gtest/gtest.h>
+
+#include <string>
+
+namespace {
+
+struct IntItem final : IntrusiveHashSetHook<IntrusiveHookMode::TRACK> {
+	int value;
+
+	IntItem(int _value) noexcept:value(_value) {}
+
+	struct Hash {
+		constexpr std::size_t operator()(const IntItem &i) noexcept {
+			return i.value;
+		}
+
+		constexpr std::size_t operator()(int i) noexcept {
+			return i;
+		}
+	};
+
+	struct Equal {
+		constexpr bool operator()(const IntItem &a,
+					  const IntItem &b) noexcept {
+			return a.value == b.value;
+		}
+	};
+};
+
+} // anonymous namespace
+
+TEST(IntrusiveHashSet, Basic)
+{
+	IntItem a{1}, b{2}, c{3}, d{4}, e{5}, f{1};
+
+	IntrusiveHashSet<IntItem, 3> set;
+
+	{
+		auto [position, inserted] = set.insert_check(2);
+		ASSERT_TRUE(inserted);
+		set.insert(position, b);
+	}
+
+	ASSERT_FALSE(set.insert_check(2).second);
+	ASSERT_FALSE(set.insert_check(b).second);
+
+	{
+		auto [position, inserted] = set.insert_check(a);
+		ASSERT_TRUE(inserted);
+		set.insert(position, a);
+	}
+
+	set.insert(c);
+
+	ASSERT_EQ(set.size(), 3);
+
+	ASSERT_NE(set.find(c), set.end());
+	ASSERT_EQ(set.find(c), set.iterator_to(c));
+	ASSERT_NE(set.find(3), set.end());
+	ASSERT_EQ(set.find(3), set.iterator_to(c));
+
+	ASSERT_EQ(set.find(4), set.end());
+	ASSERT_EQ(set.find(d), set.end());
+
+	set.erase(set.iterator_to(c));
+
+	ASSERT_EQ(set.size(), 2);
+	ASSERT_EQ(set.find(3), set.end());
+	ASSERT_EQ(set.find(c), set.end());
+
+	set.insert(c);
+	set.insert(d);
+	set.insert(e);
+
+	ASSERT_EQ(set.size(), 5);
+	ASSERT_FALSE(set.insert_check(1).second);
+	ASSERT_EQ(set.insert_check(1).first, set.iterator_to(a));
+	ASSERT_FALSE(set.insert_check(f).second);
+	ASSERT_EQ(set.insert_check(f).first, set.iterator_to(a));
+
+	ASSERT_EQ(set.find(1), set.iterator_to(a));
+	ASSERT_EQ(set.find(2), set.iterator_to(b));
+	ASSERT_EQ(set.find(3), set.iterator_to(c));
+	ASSERT_EQ(set.find(4), set.iterator_to(d));
+	ASSERT_EQ(set.find(5), set.iterator_to(e));
+
+	ASSERT_EQ(set.find(a), set.iterator_to(a));
+	ASSERT_EQ(set.find(b), set.iterator_to(b));
+	ASSERT_EQ(set.find(c), set.iterator_to(c));
+	ASSERT_EQ(set.find(d), set.iterator_to(d));
+	ASSERT_EQ(set.find(e), set.iterator_to(e));
+
+	set.erase(set.find(1));
+
+	{
+		auto [position, inserted] = set.insert_check(f);
+		ASSERT_TRUE(inserted);
+		set.insert(position, f);
+	}
+
+	ASSERT_EQ(set.find(a), set.iterator_to(f));
+	ASSERT_EQ(set.find(f), set.iterator_to(f));
+	ASSERT_EQ(set.find(1), set.iterator_to(f));
+
+	set.clear_and_dispose([](auto *i){ i->value = -1; });
+
+	ASSERT_EQ(a.value, 1);
+	ASSERT_EQ(b.value, -1);
+	ASSERT_EQ(c.value, -1);
+	ASSERT_EQ(d.value, -1);
+	ASSERT_EQ(e.value, -1);
+	ASSERT_EQ(f.value, -1);
+}

test/util/meson.build

@@ -6,6 +6,7 @@ test(
     'TestDivideString.cxx',
     'TestException.cxx',
     'TestIntrusiveForwardList.cxx',
+    'TestIntrusiveHashSet.cxx',
     'TestIntrusiveList.cxx',
     'TestMimeType.cxx',
     'TestSplitString.cxx',