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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
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tree10027f336435511475e392454359edea8e25895d /js/src/ds/OrderedHashTable.h
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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 ds_OrderedHashTable_h
+#define ds_OrderedHashTable_h
+
+/*
+ * Define two collection templates, js::OrderedHashMap and js::OrderedHashSet.
+ * They are like js::HashMap and js::HashSet except that:
+ *
+ * - Iterating over an Ordered hash table visits the entries in the order in
+ * which they were inserted. This means that unlike a HashMap, the behavior
+ * of an OrderedHashMap is deterministic (as long as the HashPolicy methods
+ * are effect-free and consistent); the hashing is a pure performance
+ * optimization.
+ *
+ * - Range objects over Ordered tables remain valid even when entries are
+ * added or removed or the table is resized. (However in the case of
+ * removing entries, note the warning on class Range below.)
+ *
+ * - The API is a little different, so it's not a drop-in replacement.
+ * In particular, the hash policy is a little different.
+ * Also, the Ordered templates lack the Ptr and AddPtr types.
+ *
+ * Hash policies
+ *
+ * See the comment about "Hash policy" in HashTable.h for general features that
+ * hash policy classes must provide. Hash policies for OrderedHashMaps and Sets
+ * differ in that the hash() method takes an extra argument:
+ * static js::HashNumber hash(Lookup, const HashCodeScrambler&);
+ * They must additionally provide a distinguished "empty" key value and the
+ * following static member functions:
+ * bool isEmpty(const Key&);
+ * void makeEmpty(Key*);
+ */
+
+#include "mozilla/HashFunctions.h"
+#include "mozilla/Move.h"
+
+using mozilla::Forward;
+using mozilla::Move;
+
+namespace js {
+
+namespace detail {
+
+/*
+ * detail::OrderedHashTable is the underlying data structure used to implement both
+ * OrderedHashMap and OrderedHashSet. Programs should use one of those two
+ * templates rather than OrderedHashTable.
+ */
+template <class T, class Ops, class AllocPolicy>
+class OrderedHashTable
+{
+ public:
+ typedef typename Ops::KeyType Key;
+ typedef typename Ops::Lookup Lookup;
+
+ struct Data
+ {
+ T element;
+ Data* chain;
+
+ Data(const T& e, Data* c) : element(e), chain(c) {}
+ Data(T&& e, Data* c) : element(Move(e)), chain(c) {}
+ };
+
+ class Range;
+ friend class Range;
+
+ private:
+ Data** hashTable; // hash table (has hashBuckets() elements)
+ Data* data; // data vector, an array of Data objects
+ // data[0:dataLength] are constructed
+ uint32_t dataLength; // number of constructed elements in data
+ uint32_t dataCapacity; // size of data, in elements
+ uint32_t liveCount; // dataLength less empty (removed) entries
+ uint32_t hashShift; // multiplicative hash shift
+ Range* ranges; // list of all live Ranges on this table
+ AllocPolicy alloc;
+ mozilla::HashCodeScrambler hcs; // don't reveal pointer hash codes
+
+ public:
+ OrderedHashTable(AllocPolicy& ap, mozilla::HashCodeScrambler hcs)
+ : hashTable(nullptr), data(nullptr), dataLength(0), ranges(nullptr), alloc(ap), hcs(hcs) {}
+
+ MOZ_MUST_USE bool init() {
+ MOZ_ASSERT(!hashTable, "init must be called at most once");
+
+ uint32_t buckets = initialBuckets();
+ Data** tableAlloc = alloc.template pod_malloc<Data*>(buckets);
+ if (!tableAlloc)
+ return false;
+ for (uint32_t i = 0; i < buckets; i++)
+ tableAlloc[i] = nullptr;
+
+ uint32_t capacity = uint32_t(buckets * fillFactor());
+ Data* dataAlloc = alloc.template pod_malloc<Data>(capacity);
+ if (!dataAlloc) {
+ alloc.free_(tableAlloc);
+ return false;
+ }
+
+ // clear() requires that members are assigned only after all allocation
+ // has succeeded, and that this->ranges is left untouched.
+ hashTable = tableAlloc;
+ data = dataAlloc;
+ dataLength = 0;
+ dataCapacity = capacity;
+ liveCount = 0;
+ hashShift = HashNumberSizeBits - initialBucketsLog2();
+ MOZ_ASSERT(hashBuckets() == buckets);
+ return true;
+ }
+
+ ~OrderedHashTable() {
+ for (Range* r = ranges; r; ) {
+ Range* next = r->next;
+ r->onTableDestroyed();
+ r = next;
+ }
+ alloc.free_(hashTable);
+ freeData(data, dataLength);
+ }
+
+ /* Return the number of elements in the table. */
+ uint32_t count() const { return liveCount; }
+
+ /* True if any element matches l. */
+ bool has(const Lookup& l) const {
+ return lookup(l) != nullptr;
+ }
+
+ /* Return a pointer to the element, if any, that matches l, or nullptr. */
+ T* get(const Lookup& l) {
+ Data* e = lookup(l, prepareHash(l));
+ return e ? &e->element : nullptr;
+ }
+
+ /* Return a pointer to the element, if any, that matches l, or nullptr. */
+ const T* get(const Lookup& l) const {
+ return const_cast<OrderedHashTable*>(this)->get(l);
+ }
+
+ /*
+ * If the table already contains an entry that matches |element|,
+ * replace that entry with |element|. Otherwise add a new entry.
+ *
+ * On success, return true, whether there was already a matching element or
+ * not. On allocation failure, return false. If this returns false, it
+ * means the element was not added to the table.
+ */
+ template <typename ElementInput>
+ MOZ_MUST_USE bool put(ElementInput&& element) {
+ HashNumber h = prepareHash(Ops::getKey(element));
+ if (Data* e = lookup(Ops::getKey(element), h)) {
+ e->element = Forward<ElementInput>(element);
+ return true;
+ }
+
+ if (dataLength == dataCapacity) {
+ // If the hashTable is more than 1/4 deleted data, simply rehash in
+ // place to free up some space. Otherwise, grow the table.
+ uint32_t newHashShift = liveCount >= dataCapacity * 0.75 ? hashShift - 1 : hashShift;
+ if (!rehash(newHashShift))
+ return false;
+ }
+
+ h >>= hashShift;
+ liveCount++;
+ Data* e = &data[dataLength++];
+ new (e) Data(Forward<ElementInput>(element), hashTable[h]);
+ hashTable[h] = e;
+ return true;
+ }
+
+ /*
+ * If the table contains an element matching l, remove it and set *foundp
+ * to true. Otherwise set *foundp to false.
+ *
+ * Return true on success, false if we tried to shrink the table and hit an
+ * allocation failure. Even if this returns false, *foundp is set correctly
+ * and the matching element was removed. Shrinking is an optimization and
+ * it's OK for it to fail.
+ */
+ bool remove(const Lookup& l, bool* foundp) {
+ // Note: This could be optimized so that removing the last entry,
+ // data[dataLength - 1], decrements dataLength. LIFO use cases would
+ // benefit.
+
+ // If a matching entry exists, empty it.
+ Data* e = lookup(l, prepareHash(l));
+ if (e == nullptr) {
+ *foundp = false;
+ return true;
+ }
+
+ *foundp = true;
+ liveCount--;
+ Ops::makeEmpty(&e->element);
+
+ // Update active Ranges.
+ uint32_t pos = e - data;
+ for (Range* r = ranges; r; r = r->next)
+ r->onRemove(pos);
+
+ // If many entries have been removed, try to shrink the table.
+ if (hashBuckets() > initialBuckets() && liveCount < dataLength * minDataFill()) {
+ if (!rehash(hashShift + 1))
+ return false;
+ }
+ return true;
+ }
+
+ /*
+ * Remove all entries.
+ *
+ * Returns false on OOM, leaving the OrderedHashTable and any live Ranges
+ * in the old state.
+ *
+ * The effect on live Ranges is the same as removing all entries; in
+ * particular, those Ranges are still live and will see any entries added
+ * after a successful clear().
+ */
+ MOZ_MUST_USE bool clear() {
+ if (dataLength != 0) {
+ Data** oldHashTable = hashTable;
+ Data* oldData = data;
+ uint32_t oldDataLength = dataLength;
+
+ hashTable = nullptr;
+ if (!init()) {
+ // init() only mutates members on success; see comment above.
+ hashTable = oldHashTable;
+ return false;
+ }
+
+ alloc.free_(oldHashTable);
+ freeData(oldData, oldDataLength);
+ for (Range* r = ranges; r; r = r->next)
+ r->onClear();
+ }
+
+ MOZ_ASSERT(hashTable);
+ MOZ_ASSERT(data);
+ MOZ_ASSERT(dataLength == 0);
+ MOZ_ASSERT(liveCount == 0);
+ return true;
+ }
+
+ /*
+ * Ranges are used to iterate over OrderedHashTables.
+ *
+ * Suppose 'Map' is some instance of OrderedHashMap, and 'map' is a Map.
+ * Then you can walk all the key-value pairs like this:
+ *
+ * for (Map::Range r = map.all(); !r.empty(); r.popFront()) {
+ * Map::Entry& pair = r.front();
+ * ... do something with pair ...
+ * }
+ *
+ * Ranges remain valid for the lifetime of the OrderedHashTable, even if
+ * entries are added or removed or the table is resized. Don't do anything
+ * to a Range, except destroy it, after the OrderedHashTable has been
+ * destroyed. (We support destroying the two objects in either order to
+ * humor the GC, bless its nondeterministic heart.)
+ *
+ * Warning: The behavior when the current front() entry is removed from the
+ * table is subtly different from js::HashTable<>::Enum::removeFront()!
+ * HashTable::Enum doesn't skip any entries when you removeFront() and then
+ * popFront(). OrderedHashTable::Range does! (This is useful for using a
+ * Range to implement JS Map.prototype.iterator.)
+ *
+ * The workaround is to call popFront() as soon as possible,
+ * before there's any possibility of modifying the table:
+ *
+ * for (Map::Range r = map.all(); !r.empty(); ) {
+ * Key key = r.front().key; // this won't modify map
+ * Value val = r.front().value; // this won't modify map
+ * r.popFront();
+ * // ...do things that might modify map...
+ * }
+ */
+ class Range
+ {
+ friend class OrderedHashTable;
+
+ // Cannot be a reference since we need to be able to do
+ // |offsetof(Range, ht)|.
+ OrderedHashTable* ht;
+
+ /* The index of front() within ht->data. */
+ uint32_t i;
+
+ /*
+ * The number of nonempty entries in ht->data to the left of front().
+ * This is used when the table is resized or compacted.
+ */
+ uint32_t count;
+
+ /*
+ * Links in the doubly-linked list of active Ranges on ht.
+ *
+ * prevp points to the previous Range's .next field;
+ * or to ht->ranges if this is the first Range in the list.
+ * next points to the next Range;
+ * or nullptr if this is the last Range in the list.
+ *
+ * Invariant: *prevp == this.
+ */
+ Range** prevp;
+ Range* next;
+
+ /*
+ * Create a Range over all the entries in ht.
+ * (This is private on purpose. End users must use ht->all().)
+ */
+ explicit Range(OrderedHashTable* ht) : ht(ht), i(0), count(0), prevp(&ht->ranges), next(ht->ranges) {
+ *prevp = this;
+ if (next)
+ next->prevp = &next;
+ seek();
+ }
+
+ public:
+ Range(const Range& other)
+ : ht(other.ht), i(other.i), count(other.count), prevp(&ht->ranges), next(ht->ranges)
+ {
+ *prevp = this;
+ if (next)
+ next->prevp = &next;
+ }
+
+ ~Range() {
+ *prevp = next;
+ if (next)
+ next->prevp = prevp;
+ }
+
+ private:
+ // Prohibit copy assignment.
+ Range& operator=(const Range& other) = delete;
+
+ void seek() {
+ while (i < ht->dataLength && Ops::isEmpty(Ops::getKey(ht->data[i].element)))
+ i++;
+ }
+
+ /*
+ * The hash table calls this when an entry is removed.
+ * j is the index of the removed entry.
+ */
+ void onRemove(uint32_t j) {
+ MOZ_ASSERT(valid());
+ if (j < i)
+ count--;
+ if (j == i)
+ seek();
+ }
+
+ /*
+ * The hash table calls this when the table is resized or compacted.
+ * Since |count| is the number of nonempty entries to the left of
+ * front(), discarding the empty entries will not affect count, and it
+ * will make i and count equal.
+ */
+ void onCompact() {
+ MOZ_ASSERT(valid());
+ i = count;
+ }
+
+ /* The hash table calls this when cleared. */
+ void onClear() {
+ MOZ_ASSERT(valid());
+ i = count = 0;
+ }
+
+ bool valid() const {
+ return next != this;
+ }
+
+ void onTableDestroyed() {
+ MOZ_ASSERT(valid());
+ prevp = &next;
+ next = this;
+ }
+
+ public:
+ bool empty() const {
+ MOZ_ASSERT(valid());
+ return i >= ht->dataLength;
+ }
+
+ /*
+ * Return the first element in the range. This must not be called if
+ * this->empty().
+ *
+ * Warning: Removing an entry from the table also removes it from any
+ * live Ranges, and a Range can become empty that way, rendering
+ * front() invalid. If in doubt, check empty() before calling front().
+ */
+ T& front() {
+ MOZ_ASSERT(valid());
+ MOZ_ASSERT(!empty());
+ return ht->data[i].element;
+ }
+
+ /*
+ * Remove the first element from this range.
+ * This must not be called if this->empty().
+ *
+ * Warning: Removing an entry from the table also removes it from any
+ * live Ranges, and a Range can become empty that way, rendering
+ * popFront() invalid. If in doubt, check empty() before calling
+ * popFront().
+ */
+ void popFront() {
+ MOZ_ASSERT(valid());
+ MOZ_ASSERT(!empty());
+ MOZ_ASSERT(!Ops::isEmpty(Ops::getKey(ht->data[i].element)));
+ count++;
+ i++;
+ seek();
+ }
+
+ /*
+ * Change the key of the front entry.
+ *
+ * This calls Ops::hash on both the current key and the new key.
+ * Ops::hash on the current key must return the same hash code as
+ * when the entry was added to the table.
+ */
+ void rekeyFront(const Key& k) {
+ MOZ_ASSERT(valid());
+ Data& entry = ht->data[i];
+ HashNumber oldHash = ht->prepareHash(Ops::getKey(entry.element)) >> ht->hashShift;
+ HashNumber newHash = ht->prepareHash(k) >> ht->hashShift;
+ Ops::setKey(entry.element, k);
+ if (newHash != oldHash) {
+ // Remove this entry from its old hash chain. (If this crashes
+ // reading nullptr, it would mean we did not find this entry on
+ // the hash chain where we expected it. That probably means the
+ // key's hash code changed since it was inserted, breaking the
+ // hash code invariant.)
+ Data** ep = &ht->hashTable[oldHash];
+ while (*ep != &entry)
+ ep = &(*ep)->chain;
+ *ep = entry.chain;
+
+ // Add it to the new hash chain. We could just insert it at the
+ // beginning of the chain. Instead, we do a bit of work to
+ // preserve the invariant that hash chains always go in reverse
+ // insertion order (descending memory order). No code currently
+ // depends on this invariant, so it's fine to kill it if
+ // needed.
+ ep = &ht->hashTable[newHash];
+ while (*ep && *ep > &entry)
+ ep = &(*ep)->chain;
+ entry.chain = *ep;
+ *ep = &entry;
+ }
+ }
+
+ static size_t offsetOfHashTable() {
+ return offsetof(Range, ht);
+ }
+ static size_t offsetOfI() {
+ return offsetof(Range, i);
+ }
+ static size_t offsetOfCount() {
+ return offsetof(Range, count);
+ }
+ static size_t offsetOfPrevP() {
+ return offsetof(Range, prevp);
+ }
+ static size_t offsetOfNext() {
+ return offsetof(Range, next);
+ }
+ };
+
+ Range all() { return Range(this); }
+
+ /*
+ * Change the value of the given key.
+ *
+ * This calls Ops::hash on both the current key and the new key.
+ * Ops::hash on the current key must return the same hash code as
+ * when the entry was added to the table.
+ */
+ void rekeyOneEntry(const Key& current, const Key& newKey, const T& element) {
+ if (current == newKey)
+ return;
+
+ Data* entry = lookup(current, prepareHash(current));
+ if (!entry)
+ return;
+
+ HashNumber oldHash = prepareHash(current) >> hashShift;
+ HashNumber newHash = prepareHash(newKey) >> hashShift;
+
+ entry->element = element;
+
+ // Remove this entry from its old hash chain. (If this crashes
+ // reading nullptr, it would mean we did not find this entry on
+ // the hash chain where we expected it. That probably means the
+ // key's hash code changed since it was inserted, breaking the
+ // hash code invariant.)
+ Data** ep = &hashTable[oldHash];
+ while (*ep != entry)
+ ep = &(*ep)->chain;
+ *ep = entry->chain;
+
+ // Add it to the new hash chain. We could just insert it at the
+ // beginning of the chain. Instead, we do a bit of work to
+ // preserve the invariant that hash chains always go in reverse
+ // insertion order (descending memory order). No code currently
+ // depends on this invariant, so it's fine to kill it if
+ // needed.
+ ep = &hashTable[newHash];
+ while (*ep && *ep > entry)
+ ep = &(*ep)->chain;
+ entry->chain = *ep;
+ *ep = entry;
+ }
+
+ static size_t offsetOfDataLength() {
+ return offsetof(OrderedHashTable, dataLength);
+ }
+ static size_t offsetOfData() {
+ return offsetof(OrderedHashTable, data);
+ }
+ static constexpr size_t offsetOfDataElement() {
+ return offsetof(Data, element);
+ }
+ static constexpr size_t sizeofData() {
+ return sizeof(Data);
+ }
+
+ private:
+ /* Logarithm base 2 of the number of buckets in the hash table initially. */
+ static uint32_t initialBucketsLog2() { return 1; }
+ static uint32_t initialBuckets() { return 1 << initialBucketsLog2(); }
+
+ /*
+ * The maximum load factor (mean number of entries per bucket).
+ * It is an invariant that
+ * dataCapacity == floor(hashBuckets() * fillFactor()).
+ *
+ * The fill factor should be between 2 and 4, and it should be chosen so that
+ * the fill factor times sizeof(Data) is close to but <= a power of 2.
+ * This fixed fill factor was chosen to make the size of the data
+ * array, in bytes, close to a power of two when sizeof(T) is 16.
+ */
+ static double fillFactor() { return 8.0 / 3.0; }
+
+ /*
+ * The minimum permitted value of (liveCount / dataLength).
+ * If that ratio drops below this value, we shrink the table.
+ */
+ static double minDataFill() { return 0.25; }
+
+ public:
+ HashNumber prepareHash(const Lookup& l) const {
+ return ScrambleHashCode(Ops::hash(l, hcs));
+ }
+
+ private:
+ /* The size of hashTable, in elements. Always a power of two. */
+ uint32_t hashBuckets() const {
+ return 1 << (HashNumberSizeBits - hashShift);
+ }
+
+ static void destroyData(Data* data, uint32_t length) {
+ for (Data* p = data + length; p != data; )
+ (--p)->~Data();
+ }
+
+ void freeData(Data* data, uint32_t length) {
+ destroyData(data, length);
+ alloc.free_(data);
+ }
+
+ Data* lookup(const Lookup& l, HashNumber h) {
+ for (Data* e = hashTable[h >> hashShift]; e; e = e->chain) {
+ if (Ops::match(Ops::getKey(e->element), l))
+ return e;
+ }
+ return nullptr;
+ }
+
+ const Data* lookup(const Lookup& l) const {
+ return const_cast<OrderedHashTable*>(this)->lookup(l, prepareHash(l));
+ }
+
+ /* This is called after rehashing the table. */
+ void compacted() {
+ // If we had any empty entries, compacting may have moved live entries
+ // to the left within |data|. Notify all live Ranges of the change.
+ for (Range* r = ranges; r; r = r->next)
+ r->onCompact();
+ }
+
+ /* Compact the entries in |data| and rehash them. */
+ void rehashInPlace() {
+ for (uint32_t i = 0, N = hashBuckets(); i < N; i++)
+ hashTable[i] = nullptr;
+ Data* wp = data;
+ Data* end = data + dataLength;
+ for (Data* rp = data; rp != end; rp++) {
+ if (!Ops::isEmpty(Ops::getKey(rp->element))) {
+ HashNumber h = prepareHash(Ops::getKey(rp->element)) >> hashShift;
+ if (rp != wp)
+ wp->element = Move(rp->element);
+ wp->chain = hashTable[h];
+ hashTable[h] = wp;
+ wp++;
+ }
+ }
+ MOZ_ASSERT(wp == data + liveCount);
+
+ while (wp != end)
+ (--end)->~Data();
+ dataLength = liveCount;
+ compacted();
+ }
+
+ /*
+ * Grow, shrink, or compact both |hashTable| and |data|.
+ *
+ * On success, this returns true, dataLength == liveCount, and there are no
+ * empty elements in data[0:dataLength]. On allocation failure, this
+ * leaves everything as it was and returns false.
+ */
+ MOZ_MUST_USE bool rehash(uint32_t newHashShift) {
+ // If the size of the table is not changing, rehash in place to avoid
+ // allocating memory.
+ if (newHashShift == hashShift) {
+ rehashInPlace();
+ return true;
+ }
+
+ size_t newHashBuckets =
+ size_t(1) << (HashNumberSizeBits - newHashShift);
+ Data** newHashTable = alloc.template pod_malloc<Data*>(newHashBuckets);
+ if (!newHashTable)
+ return false;
+ for (uint32_t i = 0; i < newHashBuckets; i++)
+ newHashTable[i] = nullptr;
+
+ uint32_t newCapacity = uint32_t(newHashBuckets * fillFactor());
+ Data* newData = alloc.template pod_malloc<Data>(newCapacity);
+ if (!newData) {
+ alloc.free_(newHashTable);
+ return false;
+ }
+
+ Data* wp = newData;
+ Data* end = data + dataLength;
+ for (Data* p = data; p != end; p++) {
+ if (!Ops::isEmpty(Ops::getKey(p->element))) {
+ HashNumber h = prepareHash(Ops::getKey(p->element)) >> newHashShift;
+ new (wp) Data(Move(p->element), newHashTable[h]);
+ newHashTable[h] = wp;
+ wp++;
+ }
+ }
+ MOZ_ASSERT(wp == newData + liveCount);
+
+ alloc.free_(hashTable);
+ freeData(data, dataLength);
+
+ hashTable = newHashTable;
+ data = newData;
+ dataLength = liveCount;
+ dataCapacity = newCapacity;
+ hashShift = newHashShift;
+ MOZ_ASSERT(hashBuckets() == newHashBuckets);
+
+ compacted();
+ return true;
+ }
+
+ // Not copyable.
+ OrderedHashTable& operator=(const OrderedHashTable&) = delete;
+ OrderedHashTable(const OrderedHashTable&) = delete;
+};
+
+} // namespace detail
+
+template <class Key, class Value, class OrderedHashPolicy, class AllocPolicy>
+class OrderedHashMap
+{
+ public:
+ class Entry
+ {
+ template <class, class, class> friend class detail::OrderedHashTable;
+ void operator=(const Entry& rhs) {
+ const_cast<Key&>(key) = rhs.key;
+ value = rhs.value;
+ }
+
+ void operator=(Entry&& rhs) {
+ MOZ_ASSERT(this != &rhs, "self-move assignment is prohibited");
+ const_cast<Key&>(key) = Move(rhs.key);
+ value = Move(rhs.value);
+ }
+
+ public:
+ Entry() : key(), value() {}
+ template <typename V>
+ Entry(const Key& k, V&& v) : key(k), value(Forward<V>(v)) {}
+ Entry(Entry&& rhs) : key(Move(rhs.key)), value(Move(rhs.value)) {}
+
+ const Key key;
+ Value value;
+
+ static size_t offsetOfKey() {
+ return offsetof(Entry, key);
+ }
+ static size_t offsetOfValue() {
+ return offsetof(Entry, value);
+ }
+ };
+
+ private:
+ struct MapOps : OrderedHashPolicy
+ {
+ typedef Key KeyType;
+ static void makeEmpty(Entry* e) {
+ OrderedHashPolicy::makeEmpty(const_cast<Key*>(&e->key));
+
+ // Clear the value. Destroying it is another possibility, but that
+ // would complicate class Entry considerably.
+ e->value = Value();
+ }
+ static const Key& getKey(const Entry& e) { return e.key; }
+ static void setKey(Entry& e, const Key& k) { const_cast<Key&>(e.key) = k; }
+ };
+
+ typedef detail::OrderedHashTable<Entry, MapOps, AllocPolicy> Impl;
+ Impl impl;
+
+ public:
+ typedef typename Impl::Range Range;
+
+ OrderedHashMap(AllocPolicy ap, mozilla::HashCodeScrambler hcs) : impl(ap, hcs) {}
+ MOZ_MUST_USE bool init() { return impl.init(); }
+ uint32_t count() const { return impl.count(); }
+ bool has(const Key& key) const { return impl.has(key); }
+ Range all() { return impl.all(); }
+ const Entry* get(const Key& key) const { return impl.get(key); }
+ Entry* get(const Key& key) { return impl.get(key); }
+ bool remove(const Key& key, bool* foundp) { return impl.remove(key, foundp); }
+ MOZ_MUST_USE bool clear() { return impl.clear(); }
+
+ template <typename V>
+ MOZ_MUST_USE bool put(const Key& key, V&& value) {
+ return impl.put(Entry(key, Forward<V>(value)));
+ }
+
+ HashNumber hash(const Key& key) const { return impl.prepareHash(key); }
+
+ void rekeyOneEntry(const Key& current, const Key& newKey) {
+ const Entry* e = get(current);
+ if (!e)
+ return;
+ return impl.rekeyOneEntry(current, newKey, Entry(newKey, e->value));
+ }
+
+ static size_t offsetOfEntryKey() {
+ return Entry::offsetOfKey();
+ }
+ static size_t offsetOfImplDataLength() {
+ return Impl::offsetOfDataLength();
+ }
+ static size_t offsetOfImplData() {
+ return Impl::offsetOfData();
+ }
+ static constexpr size_t offsetOfImplDataElement() {
+ return Impl::offsetOfDataElement();
+ }
+ static constexpr size_t sizeofImplData() {
+ return Impl::sizeofData();
+ }
+};
+
+template <class T, class OrderedHashPolicy, class AllocPolicy>
+class OrderedHashSet
+{
+ private:
+ struct SetOps : OrderedHashPolicy
+ {
+ typedef const T KeyType;
+ static const T& getKey(const T& v) { return v; }
+ static void setKey(const T& e, const T& v) { const_cast<T&>(e) = v; }
+ };
+
+ typedef detail::OrderedHashTable<T, SetOps, AllocPolicy> Impl;
+ Impl impl;
+
+ public:
+ typedef typename Impl::Range Range;
+
+ explicit OrderedHashSet(AllocPolicy ap, mozilla::HashCodeScrambler hcs) : impl(ap, hcs) {}
+ MOZ_MUST_USE bool init() { return impl.init(); }
+ uint32_t count() const { return impl.count(); }
+ bool has(const T& value) const { return impl.has(value); }
+ Range all() { return impl.all(); }
+ MOZ_MUST_USE bool put(const T& value) { return impl.put(value); }
+ bool remove(const T& value, bool* foundp) { return impl.remove(value, foundp); }
+ MOZ_MUST_USE bool clear() { return impl.clear(); }
+
+ HashNumber hash(const T& value) const { return impl.prepareHash(value); }
+
+ void rekeyOneEntry(const T& current, const T& newKey) {
+ return impl.rekeyOneEntry(current, newKey, newKey);
+ }
+
+ static size_t offsetOfEntryKey() {
+ return 0;
+ }
+ static size_t offsetOfImplDataLength() {
+ return Impl::offsetOfDataLength();
+ }
+ static size_t offsetOfImplData() {
+ return Impl::offsetOfData();
+ }
+ static constexpr size_t offsetOfImplDataElement() {
+ return Impl::offsetOfDataElement();
+ }
+ static constexpr size_t sizeofImplData() {
+ return Impl::sizeofData();
+ }
+};
+
+} // namespace js
+
+#endif /* ds_OrderedHashTable_h */