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https://github.com/mozilla-firefox/firefox
synced 2026-08-12 12:35:33 +00:00
Chris Peterson
9df75ae8c1
[[likely]] and [[unlikely]] are standard C++, allow us to reduce the number of headers included (Likely.h), and simplify the if statement's expressions. https://en.cppreference.com/w/cpp/language/attributes/likely Differential Revision: https://phabricator.services.mozilla.com/D299297
57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_dom_ProxyHandlerUtils_h
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#define mozilla_dom_ProxyHandlerUtils_h
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#include "js/Id.h"
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#include "js/Object.h" // JS::GetClass
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#include "js/PropertyDescriptor.h"
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#include "js/String.h" // JS::AtomToLinearString, JS::GetLinearString{CharAt,Length}
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#include "js/TypeDecls.h"
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#include "jsfriendapi.h" // js::StringIsArrayIndex
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#include "mozilla/TextUtils.h"
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namespace mozilla::dom {
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extern jsid s_length_id;
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// A return value of UINT32_MAX indicates "not an array index". Note, in
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// particular, that UINT32_MAX itself is not a valid array index in general.
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inline uint32_t GetArrayIndexFromId(JS::Handle<jsid> id) {
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// Much like js::IdIsIndex, except with a fast path for "length" and another
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// fast path for starting with a lowercase ascii char. Is that second one
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// really needed? I guess it is because StringIsArrayIndex is out of line...
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// as of now, use id.get() instead of id otherwise operands mismatch error
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// occurs.
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if (id.isInt()) [[likely]] {
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return id.toInt();
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}
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if (id.get() == s_length_id) [[likely]] {
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return UINT32_MAX;
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}
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if (!id.isAtom()) [[unlikely]] {
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return UINT32_MAX;
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}
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JSLinearString* str = JS::AtomToLinearString(id.toAtom());
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if (JS::GetLinearStringLength(str) == 0) [[unlikely]] {
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return UINT32_MAX;
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}
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char16_t firstChar = JS::GetLinearStringCharAt(str, 0);
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if (IsAsciiLowercaseAlpha(firstChar)) [[likely]] {
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return UINT32_MAX;
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}
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uint32_t i;
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return js::StringIsArrayIndex(str, &i) ? i : UINT32_MAX;
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}
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inline bool IsArrayIndex(uint32_t index) { return index < UINT32_MAX; }
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} // namespace mozilla::dom
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#endif /* mozilla_dom_ProxyHandlerUtils_h */
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