From 84846a5619584d574e02e6e710bf537de1a668d2 Mon Sep 17 00:00:00 2001
From: karl <karl.bittner@hexaquo.at>
Date: Mon, 15 Mar 2021 14:22:04 +0100
Subject: [PATCH] Add erase by swap

---
 Vector.h | 12 ++++++++++++
 test.cpp | 21 +++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/Vector.h b/Vector.h
index 44f86e6..5cd8690 100644
--- a/Vector.h
+++ b/Vector.h
@@ -105,6 +105,18 @@ class Vector {
         }
     }
 
+    // Erase an element by swapping the previously last element to its place
+    void erase_by_swap(unsigned int position) {
+        assert(position < element_count);
+
+        // Swap the last element to this position
+        std::swap(data[position], data[element_count - 1]);
+
+        // Delete the previous element at this position (now last)
+        data[element_count - 1].~T();
+        element_count--;
+    }
+
     T *as_array() const {
         return data;
     }
diff --git a/test.cpp b/test.cpp
index c95ad61..69f0f7c 100644
--- a/test.cpp
+++ b/test.cpp
@@ -275,4 +275,25 @@ SCENARIO("Non-default constructor", "[vector]") {
             }
         }
     }
+}
+
+SCENARIO("Erase by swap", "[vector]") {
+    GIVEN("A vector with some elements") {
+        Vector<int> v(3);
+        v.push_back(1);
+        v.push_back(2);
+        v.push_back(3);
+
+        WHEN("Erasing-by-swap the first element") {
+            v.erase_by_swap(0);
+
+            THEN("The size should have decrease by one") {
+                REQUIRE(v.size() == 2);
+            }
+
+            THEN("The previously last element should now be the first") {
+                REQUIRE(v[0] == 3);
+            }
+        }
+    }
 }
\ No newline at end of file