From 0e50b6529cf8b43d4ff7a738bf201e6058ca5ba6 Mon Sep 17 00:00:00 2001
From: Jacques Lucke <jacques@blender.org>
Date: Wed, 26 Aug 2020 10:52:35 +0200
Subject: [PATCH] BLI: support removing multiple elements from a vector

---
 source/blender/blenlib/BLI_vector.hh          | 21 ++++++++++++
 .../blender/blenlib/tests/BLI_vector_test.cc  | 32 +++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/source/blender/blenlib/BLI_vector.hh b/source/blender/blenlib/BLI_vector.hh
index 392b6cd9f47..3c90e1ab755 100644
--- a/source/blender/blenlib/BLI_vector.hh
+++ b/source/blender/blenlib/BLI_vector.hh
@@ -741,6 +741,27 @@ class Vector {
     UPDATE_VECTOR_SIZE(this);
   }
 
+  /**
+   * Remove a contiguous chunk of elements and move all values coming after it towards the front.
+   * This takes O(n) time.
+   *
+   * This is similar to std::vector::erase.
+   */
+  void remove(const int64_t start_index, const int64_t amount)
+  {
+    const int64_t old_size = this->size();
+    BLI_assert(start_index >= 0);
+    BLI_assert(amount >= 0);
+    BLI_assert(start_index + amount <= old_size);
+    const int64_t move_amount = old_size - start_index - amount;
+    for (int64_t i = 0; i < move_amount; i++) {
+      begin_[start_index + i] = std::move(begin_[start_index + amount + i]);
+    }
+    destruct_n(end_ - amount, amount);
+    end_ -= amount;
+    UPDATE_VECTOR_SIZE(this);
+  }
+
   /**
    * Do a linear search to find the value in the vector.
    * When found, return the first index, otherwise return -1.
diff --git a/source/blender/blenlib/tests/BLI_vector_test.cc b/source/blender/blenlib/tests/BLI_vector_test.cc
index 056a7aa3924..6dfab0d9e6f 100644
--- a/source/blender/blenlib/tests/BLI_vector_test.cc
+++ b/source/blender/blenlib/tests/BLI_vector_test.cc
@@ -793,4 +793,36 @@ TEST(vector, RemoveExceptions)
   EXPECT_EQ(vec.size(), 10);
 }
 
+TEST(vector, RemoveChunk)
+{
+  Vector<int> vec = {2, 3, 4, 5, 6, 7, 8};
+  EXPECT_EQ(vec.size(), 7);
+  vec.remove(2, 4);
+  EXPECT_EQ(vec.size(), 3);
+  EXPECT_EQ(vec[0], 2);
+  EXPECT_EQ(vec[1], 3);
+  EXPECT_EQ(vec[2], 8);
+  vec.remove(0, 1);
+  EXPECT_EQ(vec.size(), 2);
+  EXPECT_EQ(vec[0], 3);
+  EXPECT_EQ(vec[1], 8);
+  vec.remove(1, 1);
+  EXPECT_EQ(vec.size(), 1);
+  EXPECT_EQ(vec[0], 3);
+  vec.remove(0, 1);
+  EXPECT_EQ(vec.size(), 0);
+  vec.remove(0, 0);
+  EXPECT_EQ(vec.size(), 0);
+}
+
+TEST(vector, RemoveChunkExceptitons)
+{
+  Vector<ExceptionThrower> vec(10);
+  vec.remove(1, 3);
+  EXPECT_EQ(vec.size(), 7);
+  vec[5].throw_during_move = true;
+  EXPECT_ANY_THROW({ vec.remove(2, 3); });
+  EXPECT_EQ(vec.size(), 7);
+}
+
 }  // namespace blender::tests