From 79429b68701e306caa609c4940ae06e058e1ec2a Mon Sep 17 00:00:00 2001
From: jeffro256 <jeffro256@tutanota.com>
Date: Mon, 28 Apr 2025 12:31:01 -0500
Subject: [PATCH] upstream: add vector erase if container helper

---
 src/common/container_helpers.h | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/src/common/container_helpers.h b/src/common/container_helpers.h
index 421d195..48642c5 100644
--- a/src/common/container_helpers.h
+++ b/src/common/container_helpers.h
@@ -167,6 +167,38 @@ void for_all_in_map_erase_if(std::unordered_map<KeyT, ValueT> &map_inout, PredT
     }
 }
 
+/// convenience erasor for vectors, with total O(N) runtime. Erases all elements X when predicate(X)
+/// returns true. No guarantees are made about order of resulting vector if predicate(X) returns
+// true for any element X in vec_inout. Otherwise, vec_inout is not modified
+template <typename ValueT, typename PredT>
+void for_all_in_vector_erase_no_preserve_order_if(std::vector<ValueT> &vec_inout, PredT predicate)
+{
+    static_assert(
+            std::is_same<
+                    bool,
+                    decltype(predicate(std::declval<std::remove_cv_t<ValueT>>()))
+                >::value,
+            "invalid callable - expected callable in form bool(Value)"
+        );
+
+    for (auto vec_it = vec_inout.begin(); vec_it != vec_inout.end();)
+    {
+        if (predicate(*vec_it))
+        {
+            const auto it_to_last = vec_inout.end() - 1;
+            if (vec_it != it_to_last) // i.e. not last element
+            {
+                *vec_it = std::move(*it_to_last);
+            }
+            vec_inout.pop_back();
+        }
+        else
+        {
+            ++vec_it;
+        }
+    }
+}
+
 /// erase with a reverse iterator
 /// returned iterator is (pos + 1) if pos hadn't been erased
 template <typename ContainerT, typename FwdIterT>