utils: introduce RangeMap container and unit test.

This will allow the Vulkan backend to efficiently track the subresource
image layouts for each texture.

This is a sparse container for a series of ordered non-overlapping
integer intervals, where each interval maps to a concrete value.

libs/utils/test/test_RangeMap.cpp

@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * 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 <gtest/gtest.h>
+
+#include <utils/RangeMap.h>
+
+using namespace utils;
+
+TEST(RangeMapTest, Simple) {
+    RangeMap<int, char> map;
+    map.add(45, 104, 'c');
+    EXPECT_FALSE(map.has(104));
+    EXPECT_EQ(map.get(45), 'c');
+    EXPECT_EQ(map.get(103), 'c');
+    EXPECT_EQ(map.range_count(), 1);
+
+    // Perform a no-op.
+    map.set(103, 'c');
+    EXPECT_EQ(map.range_count(), 1);
+
+    // Extend a neighboring interval.
+    map.set(104, 'c');
+    EXPECT_TRUE(map.has(104));
+    EXPECT_EQ(map.get(104), 'c');
+    EXPECT_EQ(map.range_count(), 1);
+
+    // Add a second interval.
+    map.set(105, 'd');
+    EXPECT_EQ(map.get(105), 'd');
+    EXPECT_EQ(map.range_count(), 2);
+
+    // Extend an existing interval and wipe out the interval we just added.
+    map.set(105, 'c');
+    EXPECT_EQ(map.get(105), 'c');
+    EXPECT_EQ(map.range_count(), 1);
+
+    // Clip the endpoint of an existing interval.
+    map.set(105, 'd');
+    EXPECT_EQ(map.get(104), 'c');
+    EXPECT_EQ(map.get(105), 'd');
+    EXPECT_EQ(map.range_count(), 2);
+
+    // Extend the second interval backwards while clipping the first one.
+    map.set(104, 'd');
+    EXPECT_EQ(map.get(104), 'd');
+    EXPECT_EQ(map.get(103), 'c');
+    EXPECT_EQ(map.range_count(), 2);
+
+    // Insert a range into the middle of the first range.
+    map.add(46, 50, 'e');
+    EXPECT_EQ(map.range_count(), 4);
+    EXPECT_EQ(map.get(45), 'c');
+    EXPECT_EQ(map.get(46), 'e');
+    EXPECT_EQ(map.get(49), 'e');
+    EXPECT_EQ(map.get(50), 'c');
+
+    // Extend the range that we just added backwards, wiping out its leftward neighbor.
+    map.add(44, 50, 'e');
+    EXPECT_EQ(map.range_count(), 3);
+
+    map.reset(45);
+    EXPECT_FALSE(map.has(45));
+    EXPECT_TRUE(map.has(46));
+
+    map.clear(44, 47);
+    EXPECT_EQ(map.range_count(), 3);
+    EXPECT_FALSE(map.has(46));
+    EXPECT_TRUE(map.has(47));
+    map.clear(47, 50);
+    EXPECT_EQ(map.range_count(), 2);
+
+    // Clearing the middle of an existing interval should split it.
+    map.reset(55);
+    EXPECT_EQ(map.range_count(), 3);
+    EXPECT_TRUE(map.has(54));
+    EXPECT_FALSE(map.has(55));
+    EXPECT_TRUE(map.has(56));
+}