js/src/vm/WeakMapPtr.cpp
author Jan de Mooij <jdemooij@mozilla.com>
Sat, 28 Mar 2015 12:08:37 +0100
changeset 265209 0c030f97a04f4e34c138b878c4352423f5e920f9
parent 220817 a817b58630c872cfef3c9f84f7b9bd707a8147a5
child 265215 5b892d8ef4538ea84378ebe4a352c49d8b9aa366
permissions -rw-r--r--
Bug 1144366 - Switch SpiderMonkey and XPConnect style from |T *t| to |T* t|. r=jorendorff

/* -*- 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/. */

#include "js/WeakMapPtr.h"

#include "jsweakmap.h"

//
// Machinery for the externally-linkable JS::WeakMapPtr, which wraps js::WeakMap
// for a few public data types.
//

using namespace js;

namespace {

template<typename T>
struct DataType
{
};

template<>
struct DataType<JSObject*>
{
    typedef PreBarrieredObject PreBarriered;
    static JSObject* NullValue() { return nullptr; }
};

template<>
struct DataType<JS::Value>
{
    typedef PreBarrieredValue PreBarriered;
    static JS::Value NullValue() { return JS::UndefinedValue(); }
};

template <typename K, typename V>
struct Utils
{
    typedef typename DataType<K>::PreBarriered KeyType;
    typedef typename DataType<V>::PreBarriered ValueType;
    typedef WeakMap<KeyType, ValueType> Type;
    typedef Type* PtrType;
    static PtrType cast(void* ptr) { return static_cast<PtrType>(ptr); }
};

} /* namespace */

template <typename K, typename V>
void
JS::WeakMapPtr<K, V>::destroy()
{
    MOZ_ASSERT(initialized());
    auto map = Utils<K, V>::cast(ptr);
    // If this destruction happens mid-GC, we might be in the compartment's list
    // of known live weakmaps. If we are, remove ourselves before deleting.
    if (map->isInList())
        WeakMapBase::removeWeakMapFromList(map);
    js_delete(map);
    ptr = nullptr;
}

template <typename K, typename V>
bool
JS::WeakMapPtr<K, V>::init(JSContext* cx)
{
    MOZ_ASSERT(!initialized());
    typename Utils<K, V>::PtrType map = cx->runtime()->new_<typename Utils<K,V>::Type>(cx);
    if (!map || !map->init())
        return false;
    ptr = map;
    return true;
}

template <typename K, typename V>
void
JS::WeakMapPtr<K, V>::trace(JSTracer* trc)
{
    MOZ_ASSERT(initialized());
    return Utils<K, V>::cast(ptr)->trace(trc);
}

template <typename K, typename V>
V
JS::WeakMapPtr<K, V>::lookup(const K& key)
{
    MOZ_ASSERT(initialized());
    typename Utils<K, V>::Type::Ptr result = Utils<K, V>::cast(ptr)->lookup(key);
    if (!result)
        return DataType<V>::NullValue();
    return result->value();
}

template <typename K, typename V>
/* static */ void
JS::WeakMapPtr<K, V>::keyMarkCallback(JSTracer* trc, K key, void* data)
{
    auto map = static_cast< JS::WeakMapPtr<K, V>* >(data);
    K prior = key;
    JS_CallUnbarrieredObjectTracer(trc, &key, "WeakMapPtr key");
    return Utils<K, V>::cast(map->ptr)->rekeyIfMoved(prior, key);
}

template <typename K, typename V>
bool
JS::WeakMapPtr<K, V>::put(JSContext* cx, const K& key, const V& value)
{
    MOZ_ASSERT(initialized());
    if (!Utils<K, V>::cast(ptr)->put(key, value))
        return false;
    JS_StoreObjectPostBarrierCallback(cx, keyMarkCallback, key, this);
    // Values do not need to be barriered because only put() is supported,
    // which is always an initializing write.
    return true;
}

//
// Supported specializations of JS::WeakMap:
//

template class JS_PUBLIC_API(JS::WeakMapPtr)<JSObject*, JSObject*>;

#ifdef DEBUG
// Nobody's using this at the moment, but we want to make sure it compiles.
template class JS_PUBLIC_API(JS::WeakMapPtr)<JSObject*, JS::Value>;
#endif