From 602f571c1d72293d773ff9ea9f4a88d2e271dc7d Mon Sep 17 00:00:00 2001
From: PancakeTAS <pancake@mgnet.work>
Date: Sat, 25 Apr 2026 19:42:42 +0200
Subject: [PATCH] feat(bindless): Backport inplace_vector for constexpr

---
 .../modules/pipeline/signature/helpers.hpp    | 93 +++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 lsfg-vk-backend/src/modules/pipeline/signature/helpers.hpp

diff --git a/lsfg-vk-backend/src/modules/pipeline/signature/helpers.hpp b/lsfg-vk-backend/src/modules/pipeline/signature/helpers.hpp
new file mode 100644
index 0000000..2674ea5
--- /dev/null
+++ b/lsfg-vk-backend/src/modules/pipeline/signature/helpers.hpp
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+
+#pragma once
+
+#include <algorithm>
+#include <array>
+#include <cstddef>
+#include <initializer_list>
+#include <new>
+#include <stdexcept>
+#include <utility>
+#include <vector>
+
+namespace lsfgvk::pipeline {
+
+    /// C++26 backported inplace_vector
+    template<typename T, size_t N>
+    class inplace_vector {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunknown-warning-option"
+#pragma clang diagnostic ignored "-Wunsafe-buffer-usage"
+    public:
+        // Constructors
+        constexpr inplace_vector() = default;
+        constexpr inplace_vector(std::initializer_list<T> init) {
+            if (init.size() > N) throw std::bad_alloc();
+            for (auto& elem : init)
+                this->m_data.at(this->m_size++) = elem;
+        }
+        constexpr inplace_vector(const std::vector<T>& vec) {
+            if (vec.size() > N) throw std::bad_alloc();
+            for (const auto& elem : vec)
+                this->m_data.at(this->m_size++) = elem;
+        }
+
+        // Appending elements
+        constexpr void push_back(const T& value) {
+            if (this->m_size >= N) throw std::bad_alloc();
+            this->m_data.at(this->m_size++) = value;
+        }
+        constexpr void push_back(T&& value) {
+            if (this->m_size >= N) throw std::bad_alloc();
+            this->m_data.at(this->m_size++) = std::move(value);
+        }
+        template<typename... Args>
+        constexpr T& emplace_back(Args&&... args) {
+            if (this->m_size >= N) throw std::bad_alloc();
+            this->m_data.at(this->m_size) = T(std::forward<Args>(args)...);
+            return this->m_data.at(this->m_size++);
+        }
+        constexpr void clear() { this->m_size = 0; }
+
+        // Accessing elements
+        constexpr T& operator[](size_t idx) { return this->m_data.at(idx); }
+        constexpr const T& operator[](size_t idx) const { return this->m_data.at(idx); }
+        [[nodiscard]] constexpr T& at(size_t idx) {
+            if (idx >= this->m_size) throw std::out_of_range("Index out of range");
+            return this->m_data.at(idx);
+        }
+        [[nodiscard]] constexpr const T& at(size_t idx) const {
+            if (idx >= this->m_size) throw std::out_of_range("Index out of range");
+            return this->m_data.at(idx);
+        }
+        [[nodiscard]] constexpr T& front() { return this->m_data.front(); }
+        [[nodiscard]] constexpr const T& front() const { return this->m_data.front(); }
+        [[nodiscard]] constexpr T& back() { return this->m_data.at(this->m_size - 1); }
+        [[nodiscard]] constexpr const T& back() const { return this->m_data.at(this->m_size - 1); }
+
+        // Iterating elements
+        [[nodiscard]] constexpr T* begin() { return this->m_data.data(); }
+        [[nodiscard]] constexpr const T* begin() const { return this->m_data.data(); }
+        [[nodiscard]] constexpr const T* cbegin() const { return this->m_data.data(); }
+        [[nodiscard]] constexpr T* end() { return this->m_data.data() + this->m_size; } // NOLINT (pointer arithmetic)
+        [[nodiscard]] constexpr const T* end() const { return this->m_data.data() + this->m_size; } // NOLINT (pointer arithmetic)
+        [[nodiscard]] constexpr const T* cend() const { return this->m_data.data() + this->m_size; } // NOLINT (pointer arithmetic)
+
+        // Removing elements
+        constexpr void pop_back() {
+            if (this->m_size == 0) throw std::out_of_range("Vector is empty");
+            this->m_size--;
+        }
+
+        // Query capacity
+        [[nodiscard]] constexpr size_t size() const { return this->m_size; }
+        [[nodiscard]] constexpr size_t capacity() const { return N; }
+        [[nodiscard]] constexpr bool empty() const { return this->m_size == 0; }
+    private:
+        std::array<T, N> m_data{};
+        size_t m_size{0};
+#pragma clang diagnostic pop
+    };
+
+}