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https://github.com/LadybirdBrowser/ladybird.git
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59a28febc9
When T in HashTable<T> has a potentially slow equality check, it can be very profitable to check for a matching hash before full equality. This patch adds may_have_slow_equality_check() to AK::Traits and defaults it to true. For trivial types (pointers, integers, etc) we default it to false. This means we skip the hash check when the equality check would be a single-CPU-word compare anyway. This synergizes really well with things like HashMap<String, V> where collisions previously meant we may have to churn through multiple O(n) equality checks.
70 lines
1.8 KiB
C++
70 lines
1.8 KiB
C++
/*
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* Copyright (c) 2024, the Ladybird developers.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Forward.h>
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#include <AK/Noncopyable.h>
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#include <AK/Traits.h>
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namespace AK {
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template<typename T>
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requires(!IsLvalueReference<T> && !IsRvalueReference<T>) class [[nodiscard]] NonnullRawPtr {
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AK_MAKE_DEFAULT_COPYABLE(NonnullRawPtr);
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AK_MAKE_DEFAULT_MOVABLE(NonnullRawPtr);
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public:
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using ValueType = T;
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constexpr NonnullRawPtr() = delete;
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constexpr NonnullRawPtr(T const&&) = delete;
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constexpr NonnullRawPtr(T& other)
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: m_ptr(&other)
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{
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}
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constexpr operator bool() const = delete;
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constexpr bool operator!() const = delete;
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constexpr operator T&() { return *m_ptr; }
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constexpr operator T const&() const { return *m_ptr; }
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[[nodiscard]] ALWAYS_INLINE constexpr T& value() { return *m_ptr; }
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[[nodiscard]] ALWAYS_INLINE constexpr T const& value() const { return *m_ptr; }
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[[nodiscard]] ALWAYS_INLINE constexpr T& operator*() { return value(); }
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[[nodiscard]] ALWAYS_INLINE constexpr T const& operator*() const { return value(); }
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ALWAYS_INLINE RETURNS_NONNULL constexpr T* operator->() { return &value(); }
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ALWAYS_INLINE RETURNS_NONNULL constexpr T const* operator->() const { return &value(); }
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private:
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T* m_ptr;
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};
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template<typename T>
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struct Traits<NonnullRawPtr<T>> : public DefaultTraits<NonnullRawPtr<T>> {
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static unsigned hash(NonnullRawPtr<T> const& handle) { return Traits<T>::hash(handle); }
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static constexpr bool may_have_slow_equality_check() { return false; }
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};
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namespace Detail {
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template<typename T>
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inline constexpr bool IsHashCompatible<NonnullRawPtr<T>, T> = true;
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template<typename T>
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inline constexpr bool IsHashCompatible<T, NonnullRawPtr<T>> = true;
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}
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}
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#if USING_AK_GLOBALLY
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using AK::NonnullRawPtr;
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#endif
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