BLI: new C++ ArrayRef, Vector, Stack, ... data structures

Many generic C++ data structures have been developed in the
functions branch. This commit merges a first chunk of them into
master. The following new data structures are included:

Array: Owns a memory buffer with a fixed size. It is different
  from std::array in that the size is not part of the type.

ArrayRef: References an array owned by someone else. All elements
  in the referenced array are considered to be const. This should
  be the preferred parameter type for functions that take arrays
  as input.

MutableArrayRef: References an array owned by someone else. The
  elements in the referenced array can be changed.

IndexRange: Specifies a continuous range of integers with a start
  and end index.

IntrusiveListBaseWrapper: A utility class that allows iterating
  over ListBase instances where the prev and next pointer are
  stored in the objects directly.

Stack: A stack implemented on top of a vector.

Vector: An array that can grow dynamically.

Allocators: Three allocator types are included that can be used
  by the container types to support different use cases.

The Stack and Vector support small object optimization. So when
the amount of elements in them is below a certain threshold, no
memory allocation is performed.

Additionally, most methods have unit tests.

I'm merging this without normal code review, after I checked the
code roughly with Sergey, and after we talked about it with Brecht.

1 files changed, 131 insertions, 0 deletions

diff --git a/tests/gtests/blenlib/BLI_index_range_test.cc b/tests/gtests/blenlib/BLI_index_range_test.cc
new file mode 100644
index 00000000000..1944279999d
--- /dev/null
+++ b/tests/gtests/blenlib/BLI_index_range_test.cc
@@ -0,0 +1,131 @@
+#include "testing/testing.h"
+#include "BLI_index_range.h"
+#include "BLI_vector.h"
+
+using BLI::ArrayRef;
+using BLI::IndexRange;
+using IntVector = BLI::Vector<int>;
+
+TEST(index_range, DefaultConstructor)
+{
+  IndexRange range;
+  EXPECT_EQ(range.size(), 0);
+
+  IntVector vector;
+  for (int value : range) {
+    vector.append(value);
+  }
+  EXPECT_EQ(vector.size(), 0);
+}
+
+TEST(index_range, SingleElementRange)
+{
+  IndexRange range(4, 1);
+  EXPECT_EQ(range.size(), 1);
+  EXPECT_EQ(*range.begin(), 4);
+
+  IntVector vector;
+  for (int value : range) {
+    vector.append(value);
+  }
+
+  EXPECT_EQ(vector.size(), 1);
+  EXPECT_EQ(vector[0], 4);
+}
+
+TEST(index_range, MultipleElementRange)
+{
+  IndexRange range(6, 4);
+  EXPECT_EQ(range.size(), 4);
+
+  IntVector vector;
+  for (int value : range) {
+    vector.append(value);
+  }
+
+  EXPECT_EQ(vector.size(), 4);
+  for (uint i = 0; i < 4; i++) {
+    EXPECT_EQ(vector[i], i + 6);
+  }
+}
+
+TEST(index_range, SubscriptOperator)
+{
+  IndexRange range(5, 5);
+  EXPECT_EQ(range[0], 5);
+  EXPECT_EQ(range[1], 6);
+  EXPECT_EQ(range[2], 7);
+}
+
+TEST(index_range, Before)
+{
+  IndexRange range = IndexRange(5, 5).before(3);
+  EXPECT_EQ(range[0], 2);
+  EXPECT_EQ(range[1], 3);
+  EXPECT_EQ(range[2], 4);
+  EXPECT_EQ(range.size(), 3);
+}
+
+TEST(index_range, After)
+{
+  IndexRange range = IndexRange(5, 5).after(4);
+  EXPECT_EQ(range[0], 10);
+  EXPECT_EQ(range[1], 11);
+  EXPECT_EQ(range[2], 12);
+  EXPECT_EQ(range[3], 13);
+  EXPECT_EQ(range.size(), 4);
+}
+
+TEST(index_range, Contains)
+{
+  IndexRange range = IndexRange(5, 3);
+  EXPECT_TRUE(range.contains(5));
+  EXPECT_TRUE(range.contains(6));
+  EXPECT_TRUE(range.contains(7));
+  EXPECT_FALSE(range.contains(4));
+  EXPECT_FALSE(range.contains(8));
+}
+
+TEST(index_range, First)
+{
+  IndexRange range = IndexRange(5, 3);
+  EXPECT_EQ(range.first(), 5);
+}
+
+TEST(index_range, Last)
+{
+  IndexRange range = IndexRange(5, 3);
+  EXPECT_EQ(range.last(), 7);
+}
+
+TEST(index_range, OneAfterEnd)
+{
+  IndexRange range = IndexRange(5, 3);
+  EXPECT_EQ(range.one_after_last(), 8);
+}
+
+TEST(index_range, Start)
+{
+  IndexRange range = IndexRange(6, 2);
+  EXPECT_EQ(range.start(), 6);
+}
+
+TEST(index_range, Slice)
+{
+  IndexRange range = IndexRange(5, 15);
+  IndexRange slice = range.slice(2, 6);
+  EXPECT_EQ(slice.size(), 6);
+  EXPECT_EQ(slice.first(), 7);
+  EXPECT_EQ(slice.last(), 12);
+}
+
+TEST(index_range, AsArrayRef)
+{
+  IndexRange range = IndexRange(4, 6);
+  ArrayRef<uint> ref = range.as_array_ref();
+  EXPECT_EQ(ref.size(), 6);
+  EXPECT_EQ(ref[0], 4);
+  EXPECT_EQ(ref[1], 5);
+  EXPECT_EQ(ref[2], 6);
+  EXPECT_EQ(ref[3], 7);
+}