libutil: Introduce LinearMap

Change-Id: I68ce4c1dc17b0742690e49f62206c65f5a1a4a30

tests/unit/libutil/linear-map.cc

@@ -0,0 +1,72 @@
+#include "lix/libutil/linear-map.hh"
+
+#include <gtest/gtest.h>
+
+namespace nix {
+    TEST(LinearMap, Insert) {
+        LinearMap<size_t, int> map;
+        ASSERT_EQ(map.insert_or_assign(1, 1).second, false);
+        ASSERT_EQ(map.insert_or_assign(3, 5).second, false);
+        ASSERT_EQ(map.insert_or_assign(2, 2).second, false);
+        ASSERT_EQ(map.insert_or_assign(3, 3).second, true);
+        ASSERT_EQ(map.insert_or_assign(4, 4).second, false);
+
+        ASSERT_EQ(map.size(), 4);
+        ASSERT_EQ(map.begin()[0], std::pair((size_t) 1, 1));
+        ASSERT_EQ(map.begin()[1], std::pair((size_t) 2, 2));
+        ASSERT_EQ(map.begin()[2], std::pair((size_t) 3, 3));
+        ASSERT_EQ(map.begin()[3], std::pair((size_t) 4, 4));
+    }
+
+    TEST(LinearMap, InsertRangeSorted) {
+        LinearMap<size_t, int> map;
+        std::map<int, int> items = {
+            {3, 3},
+            {2, 2},
+            {1, 1},
+            {4, 4},
+        };
+        map.insert_range_sorted(std::begin(items), std::end(items));
+
+        ASSERT_EQ(map.size(), 4);
+        ASSERT_EQ(map.begin()[0], std::pair((size_t) 1, 1));
+        ASSERT_EQ(map.begin()[1], std::pair((size_t) 2, 2));
+        ASSERT_EQ(map.begin()[2], std::pair((size_t) 3, 3));
+        ASSERT_EQ(map.begin()[3], std::pair((size_t) 4, 4));
+    }
+
+    TEST(LinearMap, InsertRangeUnsorted) {
+        LinearMap<size_t, int> map;
+        std::vector<std::pair<int, int>> items = {
+            {3, 3},
+            {2, 2},
+            {1, 1},
+            {4, 4},
+        };
+        map.insert_range(std::begin(items), std::end(items));
+
+        ASSERT_EQ(map.size(), 4);
+        ASSERT_EQ(map.begin()[0], std::pair((size_t) 1, 1));
+        ASSERT_EQ(map.begin()[1], std::pair((size_t) 2, 2));
+        ASSERT_EQ(map.begin()[2], std::pair((size_t) 3, 3));
+        ASSERT_EQ(map.begin()[3], std::pair((size_t) 4, 4));
+    }
+
+    TEST(LinearMap, InsertRangeDuplicates) {
+        LinearMap<size_t, int> map;
+        map.insert_or_assign(2, 5);
+        std::vector<std::pair<int, int>> items = {
+            {3, 3},
+            {2, 2},
+            {1, 1},
+            {4, 4},
+        };
+        map.insert_range(std::begin(items), std::end(items));
+
+        ASSERT_EQ(map.size(), 4);
+        ASSERT_EQ(map.begin()[0], std::pair((size_t) 1, 1));
+        ASSERT_EQ(map.begin()[1], std::pair((size_t) 2, 2));
+        ASSERT_EQ(map.begin()[2], std::pair((size_t) 3, 3));
+        ASSERT_EQ(map.begin()[3], std::pair((size_t) 4, 4));
+    }
+}

tests/unit/meson.build

@@ -60,6 +60,7 @@ libutil_tests_sources = files(
   'libutil/hash.cc',
   'libutil/hilite.cc',
   'libutil/json-utils.cc',
+  'libutil/linear-map.cc',
   'libutil/logging.cc',
   'libutil/lru-cache.cc',
   'libutil/monitor-fd.cc',