From b5d224496ffb1649026944f73989c4a97f6283bd Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Fri, 11 Nov 2022 09:18:15 +0100
Subject: [PATCH] util/IntrusiveList: iterators are bidirectional

---
 src/util/IntrusiveList.hxx | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/util/IntrusiveList.hxx b/src/util/IntrusiveList.hxx
index 76d2ae1b7..3910dab09 100644
--- a/src/util/IntrusiveList.hxx
+++ b/src/util/IntrusiveList.hxx
@@ -372,7 +372,7 @@ public:
 			:cursor(_cursor) {}
 
 	public:
-		using iterator_category = std::forward_iterator_tag;
+		using iterator_category = std::bidirectional_iterator_tag;
 		using value_type = T;
 		using difference_type = std::ptrdiff_t;
 		using pointer = value_type *;
@@ -400,6 +400,17 @@ public:
 			cursor = cursor->next;
 			return *this;
 		}
+
+		iterator &operator--() noexcept {
+			cursor = cursor->prev;
+			return *this;
+		}
+
+		iterator &operator--(int) noexcept {
+			auto old = *this;
+			cursor = cursor->prev;
+			return old;
+		}
 	};
 
 	constexpr iterator begin() noexcept {
@@ -423,7 +434,7 @@ public:
 			:cursor(_cursor) {}
 
 	public:
-		using iterator_category = std::forward_iterator_tag;
+		using iterator_category = std::bidirectional_iterator_tag;
 		using value_type = const T;
 		using difference_type = std::ptrdiff_t;
 		using pointer = value_type *;
@@ -454,6 +465,17 @@ public:
 			cursor = cursor->next;
 			return *this;
 		}
+
+		iterator &operator--() noexcept {
+			cursor = cursor->prev;
+			return *this;
+		}
+
+		iterator &operator--(int) noexcept {
+			auto old = *this;
+			cursor = cursor->prev;
+			return old;
+		}
 	};
 
 	constexpr const_iterator begin() const noexcept {