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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* 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 */
#ifndef jsatom_h
#define jsatom_h
#include "mozilla/HashFunctions.h"
#include "jsalloc.h"
#include "gc/Barrier.h"
#include "gc/Marking.h"
#include "gc/Rooting.h"
#include "js/GCAPI.h"
#include "js/GCHashTable.h"
#include "vm/CommonPropertyNames.h"
class JSAtom;
class JSAutoByteString;
namespace js {
JS_STATIC_ASSERT(sizeof(HashNumber) == 4);
static MOZ_ALWAYS_INLINE js::HashNumber
HashId(jsid id)
return mozilla::HashGeneric(JSID_BITS(id));
struct JsidHasher
typedef jsid Lookup;
static HashNumber hash(const Lookup& l) {
return HashNumber(JSID_BITS(l));
static bool match(const jsid& id, const Lookup& l) {
return id == l;
* Return a printable, lossless char[] representation of a string-type atom.
* The lifetime of the result matches the lifetime of bytes.
extern const char*
AtomToPrintableString(ExclusiveContext* cx, JSAtom* atom, JSAutoByteString* bytes);
class AtomStateEntry
uintptr_t bits;
static const uintptr_t NO_TAG_MASK = uintptr_t(-1) - 1;
AtomStateEntry() : bits(0) {}
AtomStateEntry(const AtomStateEntry& other) : bits(other.bits) {}
AtomStateEntry(JSAtom* ptr, bool tagged)
: bits(uintptr_t(ptr) | uintptr_t(tagged))
MOZ_ASSERT((uintptr_t(ptr) & 0x1) == 0);
bool isPinned() const {
return bits & 0x1;
* Non-branching code sequence. Note that the const_cast is safe because
* the hash function doesn't consider the tag to be a portion of the key.
void setPinned(bool pinned) const {
const_cast<AtomStateEntry*>(this)->bits |= uintptr_t(pinned);
JSAtom* asPtr() const;
JSAtom* asPtrUnbarriered() const;
bool needsSweep() {
JSAtom* atom = asPtrUnbarriered();
return gc::IsAboutToBeFinalizedUnbarriered(&atom);
struct AtomHasher
struct Lookup
union {
const JS::Latin1Char* latin1Chars;
const char16_t* twoByteChars;
bool isLatin1;
size_t length;
const JSAtom* atom; /* Optional. */
JS::AutoCheckCannotGC nogc;
HashNumber hash;
Lookup(const char16_t* chars, size_t length)
: twoByteChars(chars), isLatin1(false), length(length), atom(nullptr)
hash = mozilla::HashString(chars, length);
Lookup(const JS::Latin1Char* chars, size_t length)
: latin1Chars(chars), isLatin1(true), length(length), atom(nullptr)
hash = mozilla::HashString(chars, length);
inline explicit Lookup(const JSAtom* atom);
static HashNumber hash(const Lookup& l) { return l.hash; }
static inline bool match(const AtomStateEntry& entry, const Lookup& lookup);
static void rekey(AtomStateEntry& k, const AtomStateEntry& newKey) { k = newKey; }
using AtomSet = js::GCHashSet<AtomStateEntry, AtomHasher, SystemAllocPolicy>;
// This class is a wrapper for AtomSet that is used to ensure the AtomSet is
// not modified. It should only expose read-only methods from AtomSet.
// Note however that the atoms within the table can be marked during GC.
class FrozenAtomSet
AtomSet* mSet;
// This constructor takes ownership of the passed-in AtomSet.
explicit FrozenAtomSet(AtomSet* set) { mSet = set; }
~FrozenAtomSet() { js_delete(mSet); }
AtomSet::Ptr readonlyThreadsafeLookup(const AtomSet::Lookup& l) const;
size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
return mSet->sizeOfIncludingThis(mallocSizeOf);
typedef AtomSet::Range Range;
AtomSet::Range all() const { return mSet->all(); }
class PropertyName;
} /* namespace js */
extern bool
AtomIsPinned(JSContext* cx, JSAtom* atom);
/* Well-known predefined C strings. */
#define DECLARE_PROTO_STR(name,code,init,clasp) extern const char js_##name##_str[];
#define DECLARE_CONST_CHAR_STR(idpart, id, text) extern const char js_##idpart##_str[];
/* Constant strings that are not atomized. */
extern const char js_break_str[];
extern const char js_case_str[];
extern const char js_catch_str[];
extern const char js_class_str[];
extern const char js_close_str[];
extern const char js_const_str[];
extern const char js_continue_str[];
extern const char js_debugger_str[];
extern const char js_default_str[];
extern const char js_do_str[];
extern const char js_else_str[];
extern const char js_enum_str[];
extern const char js_export_str[];
extern const char js_extends_str[];
extern const char js_finally_str[];
extern const char js_for_str[];
extern const char js_getter_str[];
extern const char js_if_str[];
extern const char js_implements_str[];
extern const char js_import_str[];
extern const char js_in_str[];
extern const char js_instanceof_str[];
extern const char js_interface_str[];
extern const char js_package_str[];
extern const char js_private_str[];
extern const char js_protected_str[];
extern const char js_public_str[];
extern const char js_send_str[];
extern const char js_setter_str[];
extern const char js_static_str[];
extern const char js_super_str[];
extern const char js_switch_str[];
extern const char js_this_str[];
extern const char js_try_str[];
extern const char js_typeof_str[];
extern const char js_void_str[];
extern const char js_while_str[];
extern const char js_with_str[];
namespace js {
* Atom tracing and garbage collection hooks.
MarkAtoms(JSTracer* trc);
MarkPermanentAtoms(JSTracer* trc);
MarkWellKnownSymbols(JSTracer* trc);
/* N.B. must correspond to boolean tagging behavior. */
enum PinningBehavior
DoNotPinAtom = false,
PinAtom = true
extern JSAtom*
Atomize(ExclusiveContext* cx, const char* bytes, size_t length,
js::PinningBehavior pin = js::DoNotPinAtom);
template <typename CharT>
extern JSAtom*
AtomizeChars(ExclusiveContext* cx, const CharT* chars, size_t length,
js::PinningBehavior pin = js::DoNotPinAtom);
extern JSAtom*
AtomizeString(ExclusiveContext* cx, JSString* str, js::PinningBehavior pin = js::DoNotPinAtom);
template <AllowGC allowGC>
extern JSAtom*
ToAtom(ExclusiveContext* cx, typename MaybeRooted<Value, allowGC>::HandleType v);
enum XDRMode {
template <XDRMode mode>
class XDRState;
template<XDRMode mode>
XDRAtom(XDRState<mode>* xdr, js::MutableHandleAtom atomp);
} /* namespace js */
#endif /* jsatom_h */