зеркало из https://github.com/mozilla/gecko-dev.git
63 строки
2.0 KiB
C++
63 строки
2.0 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* 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 "mozilla/Likely.h"
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#include "mozilla/Maybe.h"
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#include "mozilla/TextUtils.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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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 (MOZ_LIKELY(id.isInt())) {
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return id.toInt();
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}
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if (MOZ_LIKELY(id.get() == s_length_id)) {
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return UINT32_MAX;
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}
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if (MOZ_UNLIKELY(!id.isAtom())) {
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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 (MOZ_UNLIKELY(JS::GetLinearStringLength(str) == 0)) {
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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 (MOZ_LIKELY(IsAsciiLowercaseAlpha(firstChar))) {
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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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