[Bf-blender-cvs] [8dd4082b27e] functions: easy access of first and last element in array ref

[Jacques Lucke]

Commit: 8dd4082b27e8f39a7c9c823f6f8ba97da29aab65
Author: Jacques Lucke
Date:   Sat Jun 29 15:36:13 2019 +0200
Branches: functions
https://developer.blender.org/rB8dd4082b27e8f39a7c9c823f6f8ba97da29aab65

easy access of first and last element in array ref

===================================================================

M	source/blender/blenlib/BLI_array_ref.hpp
M	tests/gtests/blenlib/BLI_array_ref_test.cc

===================================================================

diff --git a/source/blender/blenlib/BLI_array_ref.hpp b/source/blender/blenlib/BLI_array_ref.hpp
index 1cfd2cfdac7..b41c2e78782 100644
--- a/source/blender/blenlib/BLI_array_ref.hpp
+++ b/source/blender/blenlib/BLI_array_ref.hpp
@@ -210,6 +210,26 @@ template<typename T> class ArrayRef {
     }
     return counter;
   }
+
+  /**
+   * Return a reference to the first element in the array.
+   * Asserts when the array is empty.
+   */
+  T &first()
+  {
+    BLI_assert(m_size > 0);
+    return m_start[0];
+  }
+
+  /**
+   * Return a reference to the last elemeent in the array.
+   * Asserts when the array is empty.
+   */
+  T &last()
+  {
+    BLI_assert(m_size > 0);
+    return m_start[m_size - 1];
+  }
 };
 
 template<typename ArrayT, typename ValueT, ValueT (*GetValue)(ArrayT &item)> class MappedArrayRef {
diff --git a/tests/gtests/blenlib/BLI_array_ref_test.cc b/tests/gtests/blenlib/BLI_array_ref_test.cc
index af4c31c6018..b73dd60fd3f 100644
--- a/tests/gtests/blenlib/BLI_array_ref_test.cc
+++ b/tests/gtests/blenlib/BLI_array_ref_test.cc
@@ -211,3 +211,19 @@ TEST(array_ref, CopyTo)
   EXPECT_EQ(b[1], 6);
   EXPECT_EQ(b[2], 7);
 }
+
+TEST(array_ref, FirstLast)
+{
+  std::array<int, 4> a = {6, 7, 8, 9};
+  IntArrayRef a_ref(a);
+  EXPECT_EQ(a_ref.first(), 6);
+  EXPECT_EQ(a_ref.last(), 9);
+}
+
+TEST(array_ref, FirstLast_OneElement)
+{
+  int a = 3;
+  IntArrayRef a_ref(a);
+  EXPECT_EQ(a_ref.first(), 3);
+  EXPECT_EQ(a_ref.last(), 3);
+}