From 195f20ff1706b2ae9aeb3a991245dd23f692eeea Mon Sep 17 00:00:00 2001
From: Steven Le Rouzic <steven.lerouzic@gmail.com>
Date: Thu, 26 Jun 2025 18:36:24 +0200
Subject: Add SparseHandlePool

---
 asl/handle_pool/sparse_handle_pool.hpp | 158 +++++++++++++++++++++++++++++++++
 1 file changed, 158 insertions(+)
 create mode 100644 asl/handle_pool/sparse_handle_pool.hpp

(limited to 'asl/handle_pool/sparse_handle_pool.hpp')

diff --git a/asl/handle_pool/sparse_handle_pool.hpp b/asl/handle_pool/sparse_handle_pool.hpp
new file mode 100644
index 0000000..3f4535d
--- /dev/null
+++ b/asl/handle_pool/sparse_handle_pool.hpp
@@ -0,0 +1,158 @@
+// Copyright 2025 Steven Le Rouzic
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+#pragma once
+
+#include "asl/handle_pool/index_pool.hpp"
+#include "asl/memory/allocator.hpp"
+#include "asl/containers/chunked_buffer.hpp"
+
+
+namespace asl
+{
+
+// @Todo If we want the allocator to be non-copyable, we could
+// introduce a reference allocator type that is copyable, and store
+// the "main" allocator in the pool.
+
+template<
+    is_object T,
+    int kIndexBits,
+    int kGenBits,
+    typename UserType = empty,
+    int kUserBits = 0,
+    isize_t kChunkSize = 32,
+    allocator Allocator = DefaultAllocator>
+requires copyable<Allocator>
+class SparseHandlePool
+{
+    using ThisIndexPool = IndexPool<kIndexBits, kGenBits, UserType, kUserBits, empty, Allocator>;
+
+    struct Slot
+    {
+        ThisIndexPool::handle h;
+        maybe_uninit<T> obj;
+
+        Slot() = default;
+        ASL_DELETE_COPY_MOVE(Slot);
+
+        ~Slot()
+        {
+            if (!h.is_null())
+            {
+                obj.destroy_unsafe();
+            }
+        }
+    };
+
+    using Buffer = chunked_buffer<Slot, kChunkSize, Allocator>;
+
+    ThisIndexPool m_index_pool{};
+    Buffer        m_buffer{};
+
+    using config = ThisIndexPool::handle::config;
+
+    template<typename... Args>
+    void set_object(ThisIndexPool::handle h, Args&&... args)
+    {
+        const auto index = static_cast<isize_t>(h.index());
+        if (m_buffer.size() <= index)
+        {
+            m_buffer.resize(index + 1);
+        }
+        m_buffer[index].h = h;
+        m_buffer[index].obj.construct_unsafe(std::forward<Args>(args)...);
+    }
+
+public:
+    using handle = ThisIndexPool::handle;
+
+    SparseHandlePool() requires default_constructible<Allocator> = default;
+
+    explicit SparseHandlePool(const Allocator& allocator)
+        : m_index_pool(allocator)
+        , m_buffer(allocator)
+    {}
+
+    ASL_DELETE_COPY(SparseHandlePool);
+    ASL_DEFAULT_MOVE(SparseHandlePool);
+    ~SparseHandlePool() = default;
+
+    [[nodiscard]] bool is_full() const
+    {
+        return m_index_pool.is_full();
+    }
+
+    bool is_valid(handle h) const
+    {
+        return m_index_pool.is_valid(h);
+    }
+
+    template<typename... Args>
+    option<handle> acquire(config::UserType user, Args&&... args)
+        requires config::kHasUser && constructible_from<T, Args&&...>
+    {
+        if (is_full()) { return nullopt; }
+        const auto handle = m_index_pool.acquire_ensure(user);
+        set_object(handle, std::forward<Args>(args)...);
+        return handle;
+    }
+
+    template<typename... Args>
+    option<handle> acquire(Args&&... args)
+        requires (!config::kHasUser) && constructible_from<T, Args&&...>
+    {
+        if (is_full()) { return nullopt; }
+        const auto handle = m_index_pool.acquire_ensure();
+        set_object(handle, std::forward<Args>(args)...);
+        return handle;
+    }
+
+    template<typename... Args>
+    handle acquire_ensure(config::UserType user, Args&&... args)
+        requires config::kHasUser && constructible_from<T, Args&&...>
+    {
+        ASL_ASSERT_RELEASE(!is_full());
+        const auto handle = m_index_pool.acquire_ensure(user);
+        set_object(handle, std::forward<Args>(args)...);
+        return handle;
+    }
+
+    template<typename... Args>
+    handle acquire_ensure(Args&&... args)
+        requires (!config::kHasUser) && constructible_from<T, Args&&...>
+    {
+        ASL_ASSERT_RELEASE(!is_full());
+        const auto handle = m_index_pool.acquire_ensure();
+        set_object(handle, std::forward<Args>(args)...);
+        return handle;
+    }
+
+    void release(handle h)
+    {
+        if (!is_valid(h)) { return; }
+        auto& slot = m_buffer[static_cast<isize_t>(h.index())];
+        slot.h = {};
+        slot.obj.destroy_unsafe();
+        m_index_pool.release(h);
+    }
+
+    auto get(this auto&& self, handle h)
+        -> copy_const_t<un_ref_t<decltype(self)>, T>*
+    {
+        if (!self.is_valid(h)) { return nullptr; }
+        return &std::forward<decltype(self)>(self).m_buffer[static_cast<isize_t>(h.index())]
+            .obj.as_init_unsafe();
+    }
+
+    auto get_ensure(this auto&& self, handle h)
+        -> copy_cref_t<decltype(self), T>
+    {
+        ASL_ASSERT_RELEASE(self.is_valid(h));
+        return std::forward<decltype(self)>(self).m_buffer[static_cast<isize_t>(h.index())]
+            .obj.as_init_unsafe();
+    }
+};
+
+} // namespace asl
-- 
cgit