From e3ef0929f1a05862336aad7a55713dcfdfcb06fb Mon Sep 17 00:00:00 2001
From: Max Kellermann <mk@cm4all.com>
Date: Wed, 30 Nov 2022 09:04:56 +0100
Subject: [PATCH] util/IntrusiveHashSet: add `const` overloads

---
 src/util/IntrusiveHashSet.hxx | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/util/IntrusiveHashSet.hxx b/src/util/IntrusiveHashSet.hxx
index dc10674c9..fe512272e 100644
--- a/src/util/IntrusiveHashSet.hxx
+++ b/src/util/IntrusiveHashSet.hxx
@@ -134,6 +134,7 @@ class IntrusiveHashSet {
 	std::array<Bucket, table_size> table;
 
 	using bucket_iterator = typename Bucket::iterator;
+	using const_bucket_iterator = typename Bucket::const_iterator;
 
 public:
 	using value_type = T;
@@ -248,10 +249,24 @@ public:
 		return end();
 	}
 
+	[[nodiscard]] [[gnu::pure]]
+	constexpr const_bucket_iterator find(const auto &key) const noexcept {
+		auto &bucket = GetBucket(key);
+		for (auto &i : bucket)
+			if (equal(key, i))
+				return bucket.iterator_to(i);
+
+		return end();
+	}
+
 	constexpr bucket_iterator end() noexcept {
 		return table.front().end();
 	}
 
+	constexpr const_bucket_iterator end() const noexcept {
+		return table.front().end();
+	}
+
 	constexpr void for_each(auto &&f) {
 		for (auto &bucket : table)
 			for (auto &i : bucket)
@@ -272,4 +287,12 @@ private:
 		const auto h = hash(std::forward<K>(key));
 		return table[h % table_size];
 	}
+
+	template<typename K>
+	[[gnu::pure]]
+	[[nodiscard]]
+	constexpr const auto &GetBucket(K &&key) const noexcept {
+		const auto h = hash(std::forward<K>(key));
+		return table[h % table_size];
+	}
 };