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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 jshashutil_h
#define jshashutil_h
#include "jscntxt.h"
#include "gc/Zone.h"
namespace js {
* Used to add entries to a js::HashMap or HashSet where the key depends on a GC
* thing that may be moved by generational or compacting GC between the call to
* lookupForAdd() and relookupOrAdd().
template <class T>
struct DependentAddPtr
typedef typename T::AddPtr AddPtr;
typedef typename T::Entry Entry;
template <class Lookup>
DependentAddPtr(const ExclusiveContext* cx, const T& table, const Lookup& lookup)
: addPtr(table.lookupForAdd(lookup))
, originalGcNumber(cx->zone()->gcNumber())
template <class KeyInput, class ValueInput>
bool add(ExclusiveContext* cx, T& table, const KeyInput& key, const ValueInput& value) {
bool gcHappened = originalGcNumber != cx->zone()->gcNumber();
if (gcHappened)
addPtr = table.lookupForAdd(key);
if (!table.relookupOrAdd(addPtr, key, value)) {
return false;
return true;
bool found() const { return addPtr.found(); }
explicit operator bool() const { return found(); }
const Entry& operator*() const { return *addPtr; }
const Entry* operator->() const { return &*addPtr; }
AddPtr addPtr ;
const uint64_t originalGcNumber;
DependentAddPtr() = delete;
DependentAddPtr(const DependentAddPtr&) = delete;
DependentAddPtr& operator=(const DependentAddPtr&) = delete;
} // namespace js