From 1ebc26fb787cf0f713b2df95ed80f7d715443be5 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Thu, 16 Jul 2026 11:45:24 +0200
Subject: kstd: implement erase and erase_if for vector

---
 libs/kstd/kstd/vector.hpp       | 34 +++++++++++++++++
 libs/kstd/kstd/vector.tests.cpp | 85 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 119 insertions(+)

(limited to 'libs/kstd')

diff --git a/libs/kstd/kstd/vector.hpp b/libs/kstd/kstd/vector.hpp
index d6ad232a..71c380fc 100644
--- a/libs/kstd/kstd/vector.hpp
+++ b/libs/kstd/kstd/vector.hpp
@@ -1078,6 +1078,40 @@ namespace kstd
   template<std::ranges::input_range Range, typename Allocator = kstd::allocator<std::ranges::range_value_t<Range>>>
   vector(kstd::from_range_t, Range &&, Allocator = Allocator()) -> vector<std::ranges::range_value_t<Range>, Allocator>;
 
+  //! Erase all occurrences of a given element from a vector.
+  //!
+  //! @tparam ValueType The value type of the vector.
+  //! @tparam Allocator The allocator type used by the vector.
+  //! @tparam NeedleType The type of the element to erase.
+  //! @param haystack The vector to erase all occurrences of the element from.
+  //! @param needle The element to erase from the vector.
+  //! @return The number of erased elements.
+  template<typename ValueType, typename Allocator, typename NeedleType = ValueType>
+  constexpr auto erase(vector<ValueType, Allocator> & haystack, NeedleType const & needle)
+      -> std::remove_cvref_t<decltype(haystack)>::size_type
+  {
+    auto removed = std::ranges::remove(haystack, needle);
+    haystack.erase(removed.begin(), removed.end());
+    return std::ranges::distance(removed);
+  }
+
+  //! Erase all element fulfilling a given predicate from the vector.
+  //!
+  //! @tparam ValueType The value type of the vector.
+  //! @tparam Allocator The allocator type used by the vector.
+  //! @tparam Predicate The type of the predicate to check for the elements.
+  //! @param haystack The vector to erase all occurrences of the element from.
+  //! @param predicate The predicate to check for the element.
+  //! @return The number of erased elements.
+  template<typename ValueType, typename Allocator, typename Predicate>
+  constexpr auto erase_if(vector<ValueType, Allocator> & haystack, Predicate predicate)
+      -> std::remove_cvref_t<decltype(haystack)>::size_type
+  {
+    auto removed = std::ranges::remove_if(haystack, predicate);
+    haystack.erase(removed.begin(), removed.end());
+    return std::ranges::distance(removed);
+  }
+
 }  // namespace kstd
 
 #endif
diff --git a/libs/kstd/kstd/vector.tests.cpp b/libs/kstd/kstd/vector.tests.cpp
index 72c1127a..24598bf9 100644
--- a/libs/kstd/kstd/vector.tests.cpp
+++ b/libs/kstd/kstd/vector.tests.cpp
@@ -1043,6 +1043,91 @@ SCENARIO("Vector modifiers", "[vector]")
       }
     }
 
+    WHEN("erasing an element using free erase")
+    {
+      auto erased = kstd::erase(v, 20);
+
+      THEN("the number of erased elements is 1")
+      {
+        REQUIRE(erased == 1);
+      }
+
+      THEN("the size is reduced")
+      {
+        REQUIRE(v.size() == 2);
+      }
+
+      THEN("the element is erased")
+      {
+        REQUIRE(v[0] == 10);
+        REQUIRE(v[1] == 30);
+      }
+    }
+
+    WHEN("erasing a non-existing element using free erase")
+    {
+      auto erased = kstd::erase(v, 40);
+
+      THEN("the number of erased elements is 0")
+      {
+        REQUIRE(erased == 0);
+      }
+
+      THEN("the size stays the same")
+      {
+        REQUIRE(v.size() == 3);
+      }
+
+      THEN("no element is erased")
+      {
+        REQUIRE(v[0] == 10);
+        REQUIRE(v[1] == 20);
+        REQUIRE(v[2] == 30);
+      }
+    }
+
+    WHEN("erasing a elements using free erase_if")
+    {
+      auto erased = kstd::erase_if(v, [](auto x) { return x >= 20; });
+
+      THEN("the number of erased elements is 2")
+      {
+        REQUIRE(erased == 2);
+      }
+
+      THEN("the size is reduced")
+      {
+        REQUIRE(v.size() == 1);
+      }
+
+      THEN("the elements are erased")
+      {
+        REQUIRE(v[0] == 10);
+      }
+    }
+
+    WHEN("erasing non-existing elements using free erase_if")
+    {
+      auto erased = kstd::erase_if(v, [](auto x) { return x >= 40; });
+
+      THEN("the number of erased elements is 0")
+      {
+        REQUIRE(erased == 0);
+      }
+
+      THEN("the size stays the same")
+      {
+        REQUIRE(v.size() == 3);
+      }
+
+      THEN("no element is erased")
+      {
+        REQUIRE(v[0] == 10);
+        REQUIRE(v[1] == 20);
+        REQUIRE(v[2] == 30);
+      }
+    }
+
     WHEN("appending a range")
     {
       auto initial_size = v.size();
-- 
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