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-rw-r--r--dom/bindings/ProxyHandlerUtils.h62
1 files changed, 62 insertions, 0 deletions
diff --git a/dom/bindings/ProxyHandlerUtils.h b/dom/bindings/ProxyHandlerUtils.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ProxyHandlerUtils_h
+#define mozilla_dom_ProxyHandlerUtils_h
+
+#include "mozilla/Likely.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/TextUtils.h"
+
+#include "js/Id.h"
+#include "js/Object.h" // JS::GetClass
+#include "js/PropertyDescriptor.h"
+#include "js/String.h" // JS::AtomToLinearString, JS::GetLinearString{CharAt,Length}
+#include "js/TypeDecls.h"
+
+#include "jsfriendapi.h" // js::StringIsArrayIndex
+
+namespace mozilla::dom {
+
+extern jsid s_length_id;
+
+// A return value of UINT32_MAX indicates "not an array index". Note, in
+// particular, that UINT32_MAX itself is not a valid array index in general.
+inline uint32_t GetArrayIndexFromId(JS::Handle<jsid> id) {
+ // Much like js::IdIsIndex, except with a fast path for "length" and another
+ // fast path for starting with a lowercase ascii char. Is that second one
+ // really needed? I guess it is because StringIsArrayIndex is out of line...
+ // as of now, use id.get() instead of id otherwise operands mismatch error
+ // occurs.
+ if (MOZ_LIKELY(id.isInt())) {
+ return id.toInt();
+ }
+ if (MOZ_LIKELY(id.get() == s_length_id)) {
+ return UINT32_MAX;
+ }
+ if (MOZ_UNLIKELY(!id.isAtom())) {
+ return UINT32_MAX;
+ }
+
+ JSLinearString* str = JS::AtomToLinearString(id.toAtom());
+ if (MOZ_UNLIKELY(JS::GetLinearStringLength(str) == 0)) {
+ return UINT32_MAX;
+ }
+
+ char16_t firstChar = JS::GetLinearStringCharAt(str, 0);
+ if (MOZ_LIKELY(IsAsciiLowercaseAlpha(firstChar))) {
+ return UINT32_MAX;
+ }
+
+ uint32_t i;
+ return js::StringIsArrayIndex(str, &i) ? i : UINT32_MAX;
+}
+
+inline bool IsArrayIndex(uint32_t index) { return index < UINT32_MAX; }
+
+} // namespace mozilla::dom
+
+#endif /* mozilla_dom_ProxyHandlerUtils_h */