AK: Implement minimum BinaryHeap

This enables efficient implementations of priority queues,
and will also be used in LibCompress for efficient huffman
tree generation.

2 files changed, 90 insertions, 0 deletions

diff --git a/AK/Tests/CMakeLists.txt b/AK/Tests/CMakeLists.txt
index c7057d5a9d..3d5bc360a2 100644
--- a/AK/Tests/CMakeLists.txt
+++ b/AK/Tests/CMakeLists.txt
@@ -7,6 +7,7 @@ set(AK_TEST_SOURCES
     TestAtomic.cpp
     TestBadge.cpp
     TestBase64.cpp
+    TestBinaryHeap.cpp
     TestBinarySearch.cpp
     TestBitmap.cpp
     TestByteBuffer.cpp
diff --git a/AK/Tests/TestBinaryHeap.cpp b/AK/Tests/TestBinaryHeap.cpp
new file mode 100644
index 0000000000..43d542123a
--- /dev/null
+++ b/AK/Tests/TestBinaryHeap.cpp
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2021, Idan Horowitz <idan.horowitz@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. 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 COPYRIGHT HOLDER 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 <AK/TestSuite.h>
+
+#include <AK/BinaryHeap.h>
+#include <AK/String.h>
+
+TEST_CASE(construct)
+{
+    BinaryHeap<int, int, 5> empty;
+    EXPECT(empty.is_empty());
+    EXPECT(empty.size() == 0);
+}
+
+TEST_CASE(construct_from_existing)
+{
+    int keys[] = { 3, 2, 1 };
+    char values[] = { 'c', 'b', 'a' };
+    BinaryHeap<int, char, 5> from_existing(keys, values, 3);
+    EXPECT(from_existing.size() == 3);
+    EXPECT_EQ(from_existing.pop_min(), 'a');
+    EXPECT_EQ(from_existing.pop_min(), 'b');
+    EXPECT_EQ(from_existing.pop_min(), 'c');
+}
+
+TEST_CASE(populate_int)
+{
+    BinaryHeap<int, int, 5> ints;
+    ints.insert(1, 10);
+    ints.insert(3, 20);
+    ints.insert(2, 30);
+    EXPECT_EQ(ints.size(), 3u);
+    EXPECT_EQ(ints.pop_min(), 10);
+    EXPECT_EQ(ints.size(), 2u);
+    EXPECT_EQ(ints.pop_min(), 30);
+    EXPECT_EQ(ints.size(), 1u);
+    EXPECT_EQ(ints.pop_min(), 20);
+    EXPECT_EQ(ints.size(), 0u);
+}
+
+TEST_CASE(populate_string)
+{
+    BinaryHeap<int, String, 5> strings;
+    strings.insert(1, "ABC");
+    strings.insert(2, "DEF");
+    EXPECT_EQ(strings.size(), 2u);
+    EXPECT_EQ(strings.pop_min(), "ABC");
+    EXPECT_EQ(strings.pop_min(), "DEF");
+    EXPECT(strings.is_empty());
+}
+
+TEST_CASE(large_populate_reverse)
+{
+    BinaryHeap<int, int, 1024> ints;
+    for (int i = 1023; i >= 0; i--) {
+        ints.insert(i, i);
+    }
+    EXPECT_EQ(ints.size(), 1024u);
+    for (int i = 0; i < 1024; i++) {
+        EXPECT_EQ(ints.peek_min(), i);
+        EXPECT_EQ(ints.pop_min(), i);
+    }
+}
+
+TEST_MAIN(BinaryHeap)