BLI: new C++ hash table data structures

This commit adds some new hashing based data structures to blenlib.
All of them use open addressing with probing currently.
Furthermore, they support small object optimization, but it is not
customizable yet. I'll add support for this when necessary.
The following main data structures are included:

**Set**
A collection of values, where every value must exist at most once.
This is similar to a Python `set`.

**SetVector**
A combination of a Set and a Vector. It supports fast search for
elements and maintains insertion order when there are no deletes.
All elements are stored in a continuous array. So they can be
iterated over using a normal `ArrayRef`.

**Map**
A set of key-value-pairs, where every key must exist at most once.
This is similar to a Python `dict`.

**StringMap**
A special map for the case when the keys are strings. This case is
fairly common and allows for some optimizations. Most importantly,
many unnecessary allocations can be avoided by storing strings in
a single buffer. Furthermore, the interface of this class uses
`StringRef` to avoid unnecessary conversions.

This commit is a continuation of rB369d5e8ad2bb7.

1 files changed, 243 insertions, 0 deletions

diff --git a/tests/gtests/blenlib/BLI_map_test.cc b/tests/gtests/blenlib/BLI_map_test.cc
new file mode 100644
index 00000000000..a7711fb3985
--- /dev/null
+++ b/tests/gtests/blenlib/BLI_map_test.cc
@@ -0,0 +1,243 @@
+#include "testing/testing.h"
+#include "BLI_map.h"
+#include "BLI_set.h"
+
+using IntFloatMap = BLI::Map<int, float>;
+
+TEST(map, DefaultConstructor)
+{
+  IntFloatMap map;
+  EXPECT_EQ(map.size(), 0);
+}
+
+TEST(map, AddIncreasesSize)
+{
+  IntFloatMap map;
+  EXPECT_EQ(map.size(), 0);
+  map.add(2, 5.0f);
+  EXPECT_EQ(map.size(), 1);
+  map.add(6, 2.0f);
+  EXPECT_EQ(map.size(), 2);
+}
+
+TEST(map, Contains)
+{
+  IntFloatMap map;
+  EXPECT_FALSE(map.contains(4));
+  map.add(5, 6.0f);
+  EXPECT_FALSE(map.contains(4));
+  map.add(4, 2.0f);
+  EXPECT_TRUE(map.contains(4));
+}
+
+TEST(map, LookupExisting)
+{
+  IntFloatMap map;
+  map.add(2, 6.0f);
+  map.add(4, 1.0f);
+  EXPECT_EQ(map.lookup(2), 6.0f);
+  EXPECT_EQ(map.lookup(4), 1.0f);
+}
+
+TEST(map, LookupNotExisting)
+{
+  IntFloatMap map;
+  map.add(2, 4.0f);
+  map.add(1, 1.0f);
+  EXPECT_EQ(map.lookup_ptr(0), nullptr);
+  EXPECT_EQ(map.lookup_ptr(5), nullptr);
+}
+
+TEST(map, AddMany)
+{
+  IntFloatMap map;
+  for (int i = 0; i < 100; i++) {
+    map.add(i, i);
+  }
+}
+
+TEST(map, PopItem)
+{
+  IntFloatMap map;
+  map.add(2, 3.0f);
+  map.add(1, 9.0f);
+  EXPECT_TRUE(map.contains(2));
+  EXPECT_TRUE(map.contains(1));
+
+  EXPECT_EQ(map.pop(1), 9.0f);
+  EXPECT_TRUE(map.contains(2));
+  EXPECT_FALSE(map.contains(1));
+
+  EXPECT_EQ(map.pop(2), 3.0f);
+  EXPECT_FALSE(map.contains(2));
+  EXPECT_FALSE(map.contains(1));
+}
+
+TEST(map, PopItemMany)
+{
+  IntFloatMap map;
+  for (uint i = 0; i < 100; i++) {
+    map.add_new(i, i);
+  }
+  for (uint i = 25; i < 80; i++) {
+    EXPECT_EQ(map.pop(i), i);
+  }
+  for (uint i = 0; i < 100; i++) {
+    EXPECT_EQ(map.contains(i), i < 25 || i >= 80);
+  }
+}
+
+TEST(map, ValueIterator)
+{
+  IntFloatMap map;
+  map.add(3, 5.0f);
+  map.add(1, 2.0f);
+  map.add(7, -2.0f);
+
+  BLI::Set<float> values;
+
+  uint iterations = 0;
+  for (float value : map.values()) {
+    values.add(value);
+    iterations++;
+  }
+
+  EXPECT_EQ(iterations, 3);
+  EXPECT_TRUE(values.contains(5.0f));
+  EXPECT_TRUE(values.contains(-2.0f));
+  EXPECT_TRUE(values.contains(2.0f));
+}
+
+TEST(map, KeyIterator)
+{
+  IntFloatMap map;
+  map.add(6, 3.0f);
+  map.add(2, 4.0f);
+  map.add(1, 3.0f);
+
+  BLI::Set<int> keys;
+
+  uint iterations = 0;
+  for (int key : map.keys()) {
+    keys.add(key);
+    iterations++;
+  }
+
+  EXPECT_EQ(iterations, 3);
+  EXPECT_TRUE(keys.contains(1));
+  EXPECT_TRUE(keys.contains(2));
+  EXPECT_TRUE(keys.contains(6));
+}
+
+TEST(map, ItemIterator)
+{
+  IntFloatMap map;
+  map.add(5, 3.0f);
+  map.add(2, 9.0f);
+  map.add(1, 0.0f);
+
+  BLI::Set<int> keys;
+  BLI::Set<float> values;
+
+  uint iterations = 0;
+  for (auto item : map.items()) {
+    keys.add(item.key);
+    values.add(item.value);
+    iterations++;
+  }
+
+  EXPECT_EQ(iterations, 3);
+  EXPECT_TRUE(keys.contains(5));
+  EXPECT_TRUE(keys.contains(2));
+  EXPECT_TRUE(keys.contains(1));
+  EXPECT_TRUE(values.contains(3.0f));
+  EXPECT_TRUE(values.contains(9.0f));
+  EXPECT_TRUE(values.contains(0.0f));
+}
+
+float return_42()
+{
+  return 42.0f;
+}
+
+TEST(map, LookupOrAdd_SeparateFunction)
+{
+  IntFloatMap map;
+  EXPECT_EQ(map.lookup_or_add(0, return_42), 42.0f);
+  EXPECT_EQ(map.lookup(0), 42);
+}
+
+TEST(map, LookupOrAdd_Lambdas)
+{
+  IntFloatMap map;
+  auto lambda1 = []() { return 11.0f; };
+  EXPECT_EQ(map.lookup_or_add(0, lambda1), 11.0f);
+  auto lambda2 = []() { return 20.0f; };
+  EXPECT_EQ(map.lookup_or_add(1, lambda2), 20.0f);
+
+  EXPECT_EQ(map.lookup_or_add(0, lambda2), 11.0f);
+  EXPECT_EQ(map.lookup_or_add(1, lambda1), 20.0f);
+}
+
+TEST(map, InsertOrModify)
+{
+  IntFloatMap map;
+  auto create_func = []() { return 10.0f; };
+  auto modify_func = [](float &value) { value += 5; };
+  EXPECT_TRUE(map.add_or_modify(1, create_func, modify_func));
+  EXPECT_EQ(map.lookup(1), 10.0f);
+  EXPECT_FALSE(map.add_or_modify(1, create_func, modify_func));
+  EXPECT_EQ(map.lookup(1), 15.0f);
+}
+
+TEST(map, AddOverride)
+{
+  IntFloatMap map;
+  EXPECT_FALSE(map.contains(3));
+  EXPECT_TRUE(map.add_override(3, 6.0f));
+  EXPECT_EQ(map.lookup(3), 6.0f);
+  EXPECT_FALSE(map.add_override(3, 7.0f));
+  EXPECT_EQ(map.lookup(3), 7.0f);
+  EXPECT_FALSE(map.add(3, 8.0f));
+  EXPECT_EQ(map.lookup(3), 7.0f);
+}
+
+TEST(map, MoveConstructorSmall)
+{
+  IntFloatMap map1;
+  map1.add(1, 2.0f);
+  map1.add(4, 1.0f);
+  IntFloatMap map2(std::move(map1));
+  EXPECT_EQ(map2.size(), 2);
+  EXPECT_EQ(map2.lookup(1), 2.0f);
+  EXPECT_EQ(map2.lookup(4), 1.0f);
+  EXPECT_EQ(map1.size(), 0);
+  EXPECT_EQ(map1.lookup_ptr(4), nullptr);
+}
+
+TEST(map, MoveConstructorLarge)
+{
+  IntFloatMap map1;
+  for (uint i = 0; i < 100; i++) {
+    map1.add_new(i, i);
+  }
+  IntFloatMap map2(std::move(map1));
+  EXPECT_EQ(map2.size(), 100);
+  EXPECT_EQ(map2.lookup(1), 1.0f);
+  EXPECT_EQ(map2.lookup(4), 4.0f);
+  EXPECT_EQ(map1.size(), 0);
+  EXPECT_EQ(map1.lookup_ptr(4), nullptr);
+}
+
+TEST(map, MoveAssignment)
+{
+  IntFloatMap map1;
+  map1.add(1, 2.0f);
+  map1.add(4, 1.0f);
+  IntFloatMap map2 = std::move(map1);
+  EXPECT_EQ(map2.size(), 2);
+  EXPECT_EQ(map2.lookup(1), 2.0f);
+  EXPECT_EQ(map2.lookup(4), 1.0f);
+  EXPECT_EQ(map1.size(), 0);
+  EXPECT_EQ(map1.lookup_ptr(4), nullptr);
+}