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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 http://mozilla.org/MPL/2.0/. */
#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())
{}
DependentAddPtr(DependentAddPtr&& other)
: addPtr(other.addPtr)
, originalGcNumber(other.originalGcNumber)
{}
template <class KeyInput, class ValueInput>
bool add(ExclusiveContext* cx, T& table, const KeyInput& key, const ValueInput& value) {
refreshAddPtr(cx, table, key);
if (!table.relookupOrAdd(addPtr, key, value)) {
ReportOutOfMemory(cx);
return false;
}
return true;
}
template <class KeyInput>
void remove(ExclusiveContext* cx, T& table, const KeyInput& key) {
refreshAddPtr(cx, table, key);
table.remove(addPtr);
}
bool found() const { return addPtr.found(); }
explicit operator bool() const { return found(); }
const Entry& operator*() const { return *addPtr; }
const Entry* operator->() const { return &*addPtr; }
private:
AddPtr addPtr ;
const uint64_t originalGcNumber;
template <class KeyInput>
void refreshAddPtr(ExclusiveContext* cx, T& table, const KeyInput& key) {
bool gcHappened = originalGcNumber != cx->zone()->gcNumber();
if (gcHappened)
addPtr = table.lookupForAdd(key);
}
DependentAddPtr() = delete;
DependentAddPtr(const DependentAddPtr&) = delete;
DependentAddPtr& operator=(const DependentAddPtr&) = delete;
};
template <typename T, typename Lookup>
inline auto
MakeDependentAddPtr(const ExclusiveContext* cx, T& table, const Lookup& lookup)
-> DependentAddPtr<typename mozilla::RemoveReference<decltype(table)>::Type>
{
using Ptr = DependentAddPtr<typename mozilla::RemoveReference<decltype(table)>::Type>;
return Ptr(cx, table, lookup);
}
} // namespace js
#endif
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