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GCC 14 emits a warning when an always succeeding `dynamic_cast`'s return value is compared to NULL inside the `AK::is<T>(U)` template when `T` == `U`. While warning on tautological `is` calls seems useful, it's a bit awkward when it comes from a function template where the cast may fail in some instantiation. There is a GCC bug open for it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115664 Work around the warning by performing the algorithm on the base type (`EventTarget`), with a wrapper that casts it to the more specialized input type.
48 lines
1.3 KiB
C++
48 lines
1.3 KiB
C++
/*
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* Copyright (c) 2020, Luke Wilde <lukew@serenityos.org>
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* Copyright (c) 2024, circl <circl.lastname@gmail.com>
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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 <LibWeb/DOM/Node.h>
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#include <LibWeb/DOM/ShadowRoot.h>
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namespace Web::DOM {
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// https://dom.spec.whatwg.org/#retarget
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inline EventTarget* retarget_impl(EventTarget* a, EventTarget* b)
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{
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// To retarget an object A against an object B, repeat these steps until they return an object:
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for (;;) {
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// 1. If one of the following is true then return A.
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// - A is not a node
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if (!is<Node>(a))
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return a;
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// - A’s root is not a shadow root
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auto* a_node = verify_cast<Node>(a);
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auto& a_root = a_node->root();
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if (!is<ShadowRoot>(a_root))
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return a;
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// - B is a node and A’s root is a shadow-including inclusive ancestor of B
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if (is<Node>(b) && a_root.is_shadow_including_inclusive_ancestor_of(verify_cast<Node>(*b)))
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return a;
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// 2. Set A to A’s root’s host.
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auto& a_shadow_root = verify_cast<ShadowRoot>(a_root);
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a = a_shadow_root.host();
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}
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}
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// https://dom.spec.whatwg.org/#retarget
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template<typename T>
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T* retarget(T* a, T* b)
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{
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return static_cast<T*>(retarget_impl(a, b));
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}
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}
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