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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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
// See the comment at the top of mfbt/HashTable.h for a comparison between
// PLDHashTable and mozilla::HashTable.
#ifndef nsTHashtable_h__
#define nsTHashtable_h__
#include <iterator>
#include <new>
#include <type_traits>
#include <utility>
#include "PLDHashTable.h"
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/OperatorNewExtensions.h"
#include "mozilla/PodOperations.h"
#include "mozilla/fallible.h"
#include "nsPointerHashKeys.h"
#include "nsTArrayForwardDeclare.h"
template <class EntryType>
class nsTHashtable;
namespace detail {
class nsTHashtableIteratorBase {
public:
using EndIteratorTag = PLDHashTable::Iterator::EndIteratorTag;
nsTHashtableIteratorBase(nsTHashtableIteratorBase&& aOther) = default;
nsTHashtableIteratorBase& operator=(nsTHashtableIteratorBase&& aOther) {
// User-defined because the move assignment operator is deleted in
// PLDHashtable::Iterator.
return operator=(static_cast<const nsTHashtableIteratorBase&>(aOther));
}
nsTHashtableIteratorBase(const nsTHashtableIteratorBase& aOther)
: mIterator{aOther.mIterator.Clone()} {}
nsTHashtableIteratorBase& operator=(const nsTHashtableIteratorBase& aOther) {
// Since PLDHashTable::Iterator has no assignment operator, we destroy and
// recreate mIterator.
mIterator.~Iterator();
new (&mIterator) PLDHashTable::Iterator(aOther.mIterator.Clone());
return *this;
}
explicit nsTHashtableIteratorBase(PLDHashTable::Iterator aFrom)
: mIterator{std::move(aFrom)} {}
explicit nsTHashtableIteratorBase(const PLDHashTable& aTable)
: mIterator{&const_cast<PLDHashTable&>(aTable)} {}
nsTHashtableIteratorBase(const PLDHashTable& aTable, EndIteratorTag aTag)
: mIterator{&const_cast<PLDHashTable&>(aTable), aTag} {}
bool operator==(const nsTHashtableIteratorBase& aRhs) const {
return mIterator == aRhs.mIterator;
}
bool operator!=(const nsTHashtableIteratorBase& aRhs) const {
return !(*this == aRhs);
}
protected:
PLDHashTable::Iterator mIterator;
};
// STL-style iterators to allow the use in range-based for loops, e.g.
template <typename T>
class nsTHashtableEntryIterator : public nsTHashtableIteratorBase {
friend class nsTHashtable<std::remove_const_t<T>>;
public:
using iterator_category = std::forward_iterator_tag;
using value_type = T;
using difference_type = int32_t;
using pointer = value_type*;
using reference = value_type&;
using iterator_type = nsTHashtableEntryIterator;
using const_iterator_type = nsTHashtableEntryIterator<const T>;
using nsTHashtableIteratorBase::nsTHashtableIteratorBase;
value_type* operator->() const {
return static_cast<value_type*>(mIterator.Get());
}
value_type& operator*() const {
return *static_cast<value_type*>(mIterator.Get());
}
iterator_type& operator++() {
mIterator.Next();
return *this;
}
iterator_type operator++(int) {
iterator_type it = *this;
++*this;
return it;
}
operator const_iterator_type() const {
return const_iterator_type{mIterator.Clone()};
}
};
template <typename EntryType>
class nsTHashtableKeyIterator : public nsTHashtableIteratorBase {
friend class nsTHashtable<EntryType>;
public:
using iterator_category = std::forward_iterator_tag;
using value_type = const std::decay_t<typename EntryType::KeyType>;
using difference_type = int32_t;
using pointer = value_type*;
using reference = value_type&;
using iterator_type = nsTHashtableKeyIterator;
using const_iterator_type = nsTHashtableKeyIterator;
using nsTHashtableIteratorBase::nsTHashtableIteratorBase;
value_type* operator->() const {
return &static_cast<const EntryType*>(mIterator.Get())->GetKey();
}
decltype(auto) operator*() const {
return static_cast<const EntryType*>(mIterator.Get())->GetKey();
}
iterator_type& operator++() {
mIterator.Next();
return *this;
}
iterator_type operator++(int) {
iterator_type it = *this;
++*this;
return it;
}
};
template <typename EntryType>
class nsTHashtableKeyRange {
public:
using IteratorType = nsTHashtableKeyIterator<EntryType>;
using iterator = IteratorType;
explicit nsTHashtableKeyRange(const PLDHashTable& aHashtable)
: mHashtable{aHashtable} {}
auto begin() const { return IteratorType{mHashtable}; }
auto end() const {
return IteratorType{mHashtable, typename IteratorType::EndIteratorTag{}};
}
auto cbegin() const { return begin(); }
auto cend() const { return end(); }
uint32_t Count() const { return mHashtable.EntryCount(); }
private:
const PLDHashTable& mHashtable;
};
template <typename EntryType>
auto RangeSize(const ::detail::nsTHashtableKeyRange<EntryType>& aRange) {
return aRange.Count();
}
} // namespace detail
/**
* a base class for templated hashtables.
*
* Clients will rarely need to use this class directly. Check the derived
* classes first, to see if they will meet your needs.
*
* @param EntryType the templated entry-type class that is managed by the
* hashtable. <code>EntryType</code> must extend the following declaration,
* and <strong>must not declare any virtual functions or derive from classes
* with virtual functions.</strong> Any vtable pointer would break the
* PLDHashTable code.
*<pre> class EntryType : public PLDHashEntryHdr
* {
* public: or friend nsTHashtable<EntryType>;
* // KeyType is what we use when Get()ing or Put()ing this entry
* // this should either be a simple datatype (uint32_t, nsISupports*) or
* // a const reference (const nsAString&)
* typedef something KeyType;
* // KeyTypePointer is the pointer-version of KeyType, because
* // PLDHashTable.h requires keys to cast to <code>const void*</code>
* typedef const something* KeyTypePointer;
*
* EntryType(KeyTypePointer aKey);
*
* // A copy or C++11 Move constructor must be defined, even if
* // AllowMemMove() == true, otherwise you will cause link errors.
* EntryType(const EntryType& aEnt); // Either this...
* EntryType(EntryType&& aEnt); // ...or this
*
* // the destructor must be defined... or you will cause link errors!
* ~EntryType();
*
* // KeyEquals(): does this entry match this key?
* bool KeyEquals(KeyTypePointer aKey) const;
*
* // KeyToPointer(): Convert KeyType to KeyTypePointer
* static KeyTypePointer KeyToPointer(KeyType aKey);
*
* // HashKey(): calculate the hash number
* static PLDHashNumber HashKey(KeyTypePointer aKey);
*
* // ALLOW_MEMMOVE can we move this class with memmove(), or do we have
* // to use the copy constructor?
* enum { ALLOW_MEMMOVE = true/false };
* }</pre>
*
* @see nsInterfaceHashtable
* @see nsClassHashtable
* @see nsTHashMap
* @author "Benjamin Smedberg <bsmedberg@covad.net>"
*/
template <class EntryType>
class MOZ_NEEDS_NO_VTABLE_TYPE nsTHashtable {
typedef mozilla::fallible_t fallible_t;
static_assert(std::is_pointer_v<typename EntryType::KeyTypePointer>,
"KeyTypePointer should be a pointer");
public:
// Separate constructors instead of default aInitLength parameter since
// otherwise the default no-arg constructor isn't found.
nsTHashtable()
: mTable(Ops(), sizeof(EntryType), PLDHashTable::kDefaultInitialLength) {}
explicit nsTHashtable(uint32_t aInitLength)
: mTable(Ops(), sizeof(EntryType), aInitLength) {}
/**
* destructor, cleans up and deallocates
*/
~nsTHashtable() = default;
nsTHashtable(nsTHashtable<EntryType>&& aOther);
nsTHashtable<EntryType>& operator=(nsTHashtable<EntryType>&& aOther);
nsTHashtable(const nsTHashtable<EntryType>&) = delete;
nsTHashtable& operator=(const nsTHashtable<EntryType>&) = delete;
/**
* Return the generation number for the table. This increments whenever
* the table data items are moved.
*/
uint32_t GetGeneration() const { return mTable.Generation(); }
/**
* KeyType is typedef'ed for ease of use.
*/
typedef typename EntryType::KeyType KeyType;
/**
* KeyTypePointer is typedef'ed for ease of use.
*/
typedef typename EntryType::KeyTypePointer KeyTypePointer;
/**
* Return the number of entries in the table.
* @return number of entries
*/
uint32_t Count() const { return mTable.EntryCount(); }
/**
* Return true if the hashtable is empty.
*/
bool IsEmpty() const { return Count() == 0; }
/**
* Get the entry associated with a key.
* @param aKey the key to retrieve
* @return pointer to the entry class, if the key exists; nullptr if the
* key doesn't exist
*/
EntryType* GetEntry(KeyType aKey) const {
return static_cast<EntryType*>(
mTable.Search(EntryType::KeyToPointer(aKey)));
}
/**
* Return true if an entry for the given key exists, false otherwise.
* @param aKey the key to retrieve
* @return true if the key exists, false if the key doesn't exist
*/
bool Contains(KeyType aKey) const { return !!GetEntry(aKey); }
/**
* Infallibly get the entry associated with a key, or create a new entry,
* @param aKey the key to retrieve
* @return pointer to the entry retrieved; never nullptr
*/
EntryType* PutEntry(KeyType aKey) {
// Infallible WithEntryHandle.
return WithEntryHandle(
aKey, [](auto entryHandle) { return entryHandle.OrInsert(); });
}
/**
* Fallibly get the entry associated with a key, or create a new entry,
* @param aKey the key to retrieve
* @return pointer to the entry retrieved; nullptr only if memory can't
* be allocated
*/
[[nodiscard]] EntryType* PutEntry(KeyType aKey, const fallible_t& aFallible) {
return WithEntryHandle(aKey, aFallible, [](auto maybeEntryHandle) {
return maybeEntryHandle ? maybeEntryHandle->OrInsert() : nullptr;
});
}
/**
* Get the entry associated with a key, or create a new entry using infallible
* allocation and insert that.
* @param aKey the key to retrieve
* @param aEntry will be assigned (if non-null) to the entry that was
* found or created
* @return true if a new entry was created, or false if an existing entry
* was found
*/
[[nodiscard]] bool EnsureInserted(KeyType aKey,
EntryType** aEntry = nullptr) {
auto oldCount = Count();
EntryType* entry = PutEntry(aKey);
if (aEntry) {
*aEntry = entry;
}
return oldCount != Count();
}
/**
* Remove the entry associated with a key.
* @param aKey of the entry to remove
*/
void RemoveEntry(KeyType aKey) {
mTable.Remove(EntryType::KeyToPointer(aKey));
}
/**
* Lookup the entry associated with aKey and remove it if found, otherwise
* do nothing.
* @param aKey of the entry to remove
* @return true if an entry was found and removed, or false if no entry
* was found for aKey
*/
bool EnsureRemoved(KeyType aKey) {
auto* entry = GetEntry(aKey);
if (entry) {
RemoveEntry(entry);
return true;
}
return false;
}
/**
* Remove the entry associated with a key.
* @param aEntry the entry-pointer to remove (obtained from GetEntry)
*/
void RemoveEntry(EntryType* aEntry) { mTable.RemoveEntry(aEntry); }
/**
* Remove the entry associated with a key, but don't resize the hashtable.
* This is a low-level method, and is not recommended unless you know what
* you're doing. If you use it, please add a comment explaining why you
* didn't use RemoveEntry().
* @param aEntry the entry-pointer to remove (obtained from GetEntry)
*/
void RawRemoveEntry(EntryType* aEntry) { mTable.RawRemove(aEntry); }
protected:
class EntryHandle {
public:
EntryHandle(EntryHandle&& aOther) = default;
~EntryHandle() = default;
EntryHandle(const EntryHandle&) = delete;
EntryHandle& operator=(const EntryHandle&) = delete;
EntryHandle& operator=(const EntryHandle&&) = delete;
KeyType Key() const { return mKey; }
bool HasEntry() const { return mEntryHandle.HasEntry(); }
explicit operator bool() const { return mEntryHandle.operator bool(); }
EntryType* Entry() { return static_cast<EntryType*>(mEntryHandle.Entry()); }
void Insert() { InsertInternal(); }
EntryType* OrInsert() {
if (!HasEntry()) {
Insert();
}
return Entry();
}
void Remove() { mEntryHandle.Remove(); }
void OrRemove() { mEntryHandle.OrRemove(); }
protected:
template <typename... Args>
void InsertInternal(Args&&... aArgs) {
MOZ_RELEASE_ASSERT(!HasEntry());
mEntryHandle.Insert([&](PLDHashEntryHdr* entry) {
new (mozilla::KnownNotNull, entry) EntryType(
EntryType::KeyToPointer(mKey), std::forward<Args>(aArgs)...);
});
}
private:
friend class nsTHashtable;
EntryHandle(KeyType aKey, PLDHashTable::EntryHandle&& aEntryHandle)
: mKey(aKey), mEntryHandle(std::move(aEntryHandle)) {}
KeyType mKey;
PLDHashTable::EntryHandle mEntryHandle;
};
template <class F>
auto WithEntryHandle(KeyType aKey, F&& aFunc)
-> std::invoke_result_t<F, EntryHandle&&> {
return this->mTable.WithEntryHandle(
EntryType::KeyToPointer(aKey),
[&aKey, &aFunc](auto entryHandle) -> decltype(auto) {
return std::forward<F>(aFunc)(
EntryHandle{aKey, std::move(entryHandle)});
});
}
template <class F>
auto WithEntryHandle(KeyType aKey, const mozilla::fallible_t& aFallible,
F&& aFunc)
-> std::invoke_result_t<F, mozilla::Maybe<EntryHandle>&&> {
return this->mTable.WithEntryHandle(
EntryType::KeyToPointer(aKey), aFallible,
[&aKey, &aFunc](auto maybeEntryHandle) {
return std::forward<F>(aFunc)(
maybeEntryHandle
? mozilla::Some(EntryHandle{aKey, maybeEntryHandle.extract()})
: mozilla::Nothing());
});
}
public:
class ConstIterator {
public:
explicit ConstIterator(nsTHashtable* aTable)
: mBaseIterator(&aTable->mTable) {}
~ConstIterator() = default;
KeyType Key() const { return Get()->GetKey(); }
const EntryType* Get() const {
return static_cast<const EntryType*>(mBaseIterator.Get());
}
bool Done() const { return mBaseIterator.Done(); }
void Next() { mBaseIterator.Next(); }
ConstIterator() = delete;
ConstIterator(const ConstIterator&) = delete;
ConstIterator(ConstIterator&& aOther) = delete;
ConstIterator& operator=(const ConstIterator&) = delete;
ConstIterator& operator=(ConstIterator&&) = delete;
protected:
PLDHashTable::Iterator mBaseIterator;
};
// This is an iterator that also allows entry removal. Example usage:
//
// for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {
// Entry* entry = iter.Get();
// // ... do stuff with |entry| ...
// // ... possibly call iter.Remove() once ...
// }
//
class Iterator final : public ConstIterator {
public:
using ConstIterator::ConstIterator;
using ConstIterator::Get;
EntryType* Get() const {
return static_cast<EntryType*>(this->mBaseIterator.Get());
}
void Remove() { this->mBaseIterator.Remove(); }
};
Iterator Iter() { return Iterator(this); }
ConstIterator ConstIter() const {
return ConstIterator(const_cast<nsTHashtable*>(this));
}
using const_iterator = ::detail::nsTHashtableEntryIterator<const EntryType>;
using iterator = ::detail::nsTHashtableEntryIterator<EntryType>;
iterator begin() { return iterator{mTable}; }
const_iterator begin() const { return const_iterator{mTable}; }
const_iterator cbegin() const { return begin(); }
iterator end() {
return iterator{mTable, typename iterator::EndIteratorTag{}};
}
const_iterator end() const {
return const_iterator{mTable, typename const_iterator::EndIteratorTag{}};
}
const_iterator cend() const { return end(); }
void Remove(const_iterator& aIter) { aIter.mIterator.Remove(); }
/**
* Return a range of the keys (of KeyType). Note this range iterates over the
* keys in place, so modifications to the nsTHashtable invalidate the range
* while it's iterated, except when calling Remove() with a key iterator
* derived from that range.
*/
auto Keys() const {
return ::detail::nsTHashtableKeyRange<EntryType>{mTable};
}
/**
* Remove an entry from a key range, specified via a key iterator, e.g.
*
* for (auto it = hash.Keys().begin(), end = hash.Keys().end();
* it != end; * ++it) {
* if (*it > 42) { hash.Remove(it); }
* }
*/
void Remove(::detail::nsTHashtableKeyIterator<EntryType>& aIter) {
aIter.mIterator.Remove();
}
/**
* Remove all entries, return hashtable to "pristine" state. It's
* conceptually the same as calling the destructor and then re-calling the
* constructor.
*/
void Clear() { mTable.Clear(); }
/**
* Measure the size of the table's entry storage. Does *not* measure anything
* hanging off table entries; hence the "Shallow" prefix. To measure that,
* either use SizeOfExcludingThis() or iterate manually over the entries,
* calling SizeOfExcludingThis() on each one.
*
* @param aMallocSizeOf the function used to measure heap-allocated blocks
* @return the measured shallow size of the table
*/
size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
return mTable.ShallowSizeOfExcludingThis(aMallocSizeOf);
}
/**
* Like ShallowSizeOfExcludingThis, but includes sizeof(*this).
*/
size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
}
/**
* This is a "deep" measurement of the table. To use it, |EntryType| must
* define SizeOfExcludingThis, and that method will be called on all live
* entries.
*/
size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
size_t n = ShallowSizeOfExcludingThis(aMallocSizeOf);
for (auto iter = ConstIter(); !iter.Done(); iter.Next()) {
n += (*iter.Get()).SizeOfExcludingThis(aMallocSizeOf);
}
return n;
}
/**
* Like SizeOfExcludingThis, but includes sizeof(*this).
*/
size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
}
/**
* Swap the elements in this hashtable with the elements in aOther.
*/
void SwapElements(nsTHashtable<EntryType>& aOther) {
MOZ_ASSERT_IF(this->mTable.Ops() && aOther.mTable.Ops(),
this->mTable.Ops() == aOther.mTable.Ops());
std::swap(this->mTable, aOther.mTable);
}
/**
* Mark the table as constant after initialization.
*
* This will prevent assertions when a read-only hash is accessed on multiple
* threads without synchronization.
*/
void MarkImmutable() { mTable.MarkImmutable(); }
protected:
PLDHashTable mTable;
static PLDHashNumber s_HashKey(const void* aKey);
static bool s_MatchEntry(const PLDHashEntryHdr* aEntry, const void* aKey);
static void s_CopyEntry(PLDHashTable* aTable, const PLDHashEntryHdr* aFrom,
PLDHashEntryHdr* aTo);
static void s_ClearEntry(PLDHashTable* aTable, PLDHashEntryHdr* aEntry);
private:
// copy constructor, not implemented
nsTHashtable(nsTHashtable<EntryType>& aToCopy) = delete;
/**
* Gets the table's ops.
*/
static const PLDHashTableOps* Ops();
// assignment operator, not implemented
nsTHashtable<EntryType>& operator=(nsTHashtable<EntryType>& aToEqual) =
delete;
};
namespace mozilla {
namespace detail {
// Like PLDHashTable::MoveEntryStub, but specialized for fixed N (i.e. the size
// of the entries in the hashtable). Saves a memory read to figure out the size
// from the table and gives the compiler the opportunity to inline the memcpy.
//
// We define this outside of nsTHashtable so only one copy exists for every N,
// rather than separate copies for every EntryType used with nsTHashtable.
template <size_t N>
static void FixedSizeEntryMover(PLDHashTable*, const PLDHashEntryHdr* aFrom,
PLDHashEntryHdr* aTo) {
memcpy(aTo, aFrom, N);
}
} // namespace detail
} // namespace mozilla
//
// template definitions
//
template <class EntryType>
nsTHashtable<EntryType>::nsTHashtable(nsTHashtable<EntryType>&& aOther)
: mTable(std::move(aOther.mTable)) {}
template <class EntryType>
nsTHashtable<EntryType>& nsTHashtable<EntryType>::operator=(
nsTHashtable<EntryType>&& aOther) {
mTable = std::move(aOther.mTable);
return *this;
}
template <class EntryType>
/* static */ const PLDHashTableOps* nsTHashtable<EntryType>::Ops() {
// If this variable is a global variable, we get strange start-up failures on
// function avoids that problem.
static const PLDHashTableOps sOps = {
s_HashKey, s_MatchEntry,
EntryType::ALLOW_MEMMOVE
? mozilla::detail::FixedSizeEntryMover<sizeof(EntryType)>
: s_CopyEntry,
// Simplify hashtable clearing in case our entries are trivially
// destructible.
std::is_trivially_destructible_v<EntryType> ? nullptr : s_ClearEntry,
// We don't use a generic initEntry hook because we want to allow
// initialization of data members defined in derived classes directly
// in the entry constructor (for example when a member can't be default
// constructed).
nullptr};
return &sOps;
}
// static definitions
template <class EntryType>
PLDHashNumber nsTHashtable<EntryType>::s_HashKey(const void* aKey) {
return EntryType::HashKey(static_cast<KeyTypePointer>(aKey));
}
template <class EntryType>
bool nsTHashtable<EntryType>::s_MatchEntry(const PLDHashEntryHdr* aEntry,
const void* aKey) {
return (static_cast<const EntryType*>(aEntry))
->KeyEquals(static_cast<KeyTypePointer>(aKey));
}
template <class EntryType>
void nsTHashtable<EntryType>::s_CopyEntry(PLDHashTable* aTable,
const PLDHashEntryHdr* aFrom,
PLDHashEntryHdr* aTo) {
auto* fromEntry = const_cast<std::remove_const_t<EntryType>*>(
static_cast<const EntryType*>(aFrom));
new (mozilla::KnownNotNull, aTo) EntryType(std::move(*fromEntry));
fromEntry->~EntryType();
}
template <class EntryType>
void nsTHashtable<EntryType>::s_ClearEntry(PLDHashTable* aTable,
PLDHashEntryHdr* aEntry) {
static_cast<EntryType*>(aEntry)->~EntryType();
}
class nsCycleCollectionTraversalCallback;
template <class EntryType>
inline void ImplCycleCollectionUnlink(nsTHashtable<EntryType>& aField) {
aField.Clear();
}
template <class EntryType>
inline void ImplCycleCollectionTraverse(
nsCycleCollectionTraversalCallback& aCallback,
nsTHashtable<EntryType>& aField, const char* aName, uint32_t aFlags = 0) {
for (auto iter = aField.Iter(); !iter.Done(); iter.Next()) {
EntryType* entry = iter.Get();
ImplCycleCollectionTraverse(aCallback, *entry, aName, aFlags);
}
}
/**
* For nsTHashtable with pointer entries, we can have a template specialization
* that layers a typed T* interface on top of a common implementation that
* works internally with void pointers. This arrangement saves code size and
* might slightly improve performance as well.
*/
/**
* We need a separate entry type class for the inheritance structure of the
* nsTHashtable specialization below; nsVoidPtrHashKey is simply typedefed to a
* specialization of nsPtrHashKey, and the formulation:
*
* class nsTHashtable<nsPtrHashKey<T>> :
* protected nsTHashtable<nsPtrHashKey<const void>
*
* is not going to turn out very well, since we'd wind up with an nsTHashtable
* instantiation that is its own base class.
*/
namespace detail {
class VoidPtrHashKey : public nsPtrHashKey<const void> {
typedef nsPtrHashKey<const void> Base;
public:
explicit VoidPtrHashKey(const void* aKey) : Base(aKey) {}
};
} // namespace detail
/**
* See the main nsTHashtable documentation for descriptions of this class's
* methods.
*/
template <typename T>
class nsTHashtable<nsPtrHashKey<T>>
: protected nsTHashtable<::detail::VoidPtrHashKey> {
typedef nsTHashtable<::detail::VoidPtrHashKey> Base;
typedef nsPtrHashKey<T> EntryType;
// We play games with reinterpret_cast'ing between these two classes, so
// try to ensure that playing said games is reasonable.
static_assert(sizeof(nsPtrHashKey<T>) == sizeof(::detail::VoidPtrHashKey),
"hash keys must be the same size");
nsTHashtable(const nsTHashtable& aOther) = delete;
nsTHashtable& operator=(const nsTHashtable& aOther) = delete;
public:
nsTHashtable() = default;
explicit nsTHashtable(uint32_t aInitLength) : Base(aInitLength) {}
~nsTHashtable() = default;
nsTHashtable(nsTHashtable&&) = default;
using Base::Clear;
using Base::Count;
using Base::GetGeneration;
using Base::IsEmpty;
using Base::MarkImmutable;
using Base::ShallowSizeOfExcludingThis;
using Base::ShallowSizeOfIncludingThis;
/* Wrapper functions */
EntryType* GetEntry(T* aKey) const {
return reinterpret_cast<EntryType*>(Base::GetEntry(aKey));
}
bool Contains(T* aKey) const { return Base::Contains(aKey); }
EntryType* PutEntry(T* aKey) {
return reinterpret_cast<EntryType*>(Base::PutEntry(aKey));
}
[[nodiscard]] EntryType* PutEntry(T* aKey,
const mozilla::fallible_t& aFallible) {
return reinterpret_cast<EntryType*>(Base::PutEntry(aKey, aFallible));
}
[[nodiscard]] bool EnsureInserted(T* aKey, EntryType** aEntry = nullptr) {
return Base::EnsureInserted(
aKey, reinterpret_cast<::detail::VoidPtrHashKey**>(aEntry));
}
void RemoveEntry(T* aKey) { Base::RemoveEntry(aKey); }
bool EnsureRemoved(T* aKey) { return Base::EnsureRemoved(aKey); }
void RemoveEntry(EntryType* aEntry) {
Base::RemoveEntry(reinterpret_cast<::detail::VoidPtrHashKey*>(aEntry));
}
void RawRemoveEntry(EntryType* aEntry) {
Base::RawRemoveEntry(reinterpret_cast<::detail::VoidPtrHashKey*>(aEntry));
}
protected:
class EntryHandle : protected Base::EntryHandle {
public:
using Base = nsTHashtable::Base::EntryHandle;
EntryHandle(EntryHandle&& aOther) = default;
~EntryHandle() = default;
EntryHandle(const EntryHandle&) = delete;
EntryHandle& operator=(const EntryHandle&) = delete;
EntryHandle& operator=(const EntryHandle&&) = delete;
using Base::Key;
using Base::HasEntry;
using Base::operator bool;
EntryType* Entry() { return reinterpret_cast<EntryType*>(Base::Entry()); }
using Base::Insert;
EntryType* OrInsert() {
if (!HasEntry()) {
Insert();
}
return Entry();
}
using Base::Remove;
using Base::OrRemove;
private:
friend class nsTHashtable;
explicit EntryHandle(Base&& aBase) : Base(std::move(aBase)) {}
};
template <class F>
auto WithEntryHandle(KeyType aKey, F aFunc)
-> std::invoke_result_t<F, EntryHandle&&> {
return Base::WithEntryHandle(aKey, [&aFunc](auto entryHandle) {
return aFunc(EntryHandle{std::move(entryHandle)});
});
}
template <class F>
auto WithEntryHandle(KeyType aKey, const mozilla::fallible_t& aFallible,
F aFunc)
-> std::invoke_result_t<F, mozilla::Maybe<EntryHandle>&&> {
return Base::WithEntryHandle(
aKey, aFallible, [&aFunc](auto maybeEntryHandle) {
return aFunc(maybeEntryHandle ? mozilla::Some(EntryHandle{
maybeEntryHandle.extract()})
: mozilla::Nothing());
});
}
public:
class ConstIterator {
public:
explicit ConstIterator(nsTHashtable* aTable)
: mBaseIterator(&aTable->mTable) {}
~ConstIterator() = default;
KeyType Key() const { return Get()->GetKey(); }
const EntryType* Get() const {
return static_cast<const EntryType*>(mBaseIterator.Get());
}
bool Done() const { return mBaseIterator.Done(); }
void Next() { mBaseIterator.Next(); }
ConstIterator() = delete;
ConstIterator(const ConstIterator&) = delete;
ConstIterator(ConstIterator&& aOther) = delete;
ConstIterator& operator=(const ConstIterator&) = delete;
ConstIterator& operator=(ConstIterator&&) = delete;
protected:
PLDHashTable::Iterator mBaseIterator;
};
class Iterator final : public ConstIterator {
public:
using ConstIterator::ConstIterator;
using ConstIterator::Get;
EntryType* Get() const {
return static_cast<EntryType*>(this->mBaseIterator.Get());
}
void Remove() { this->mBaseIterator.Remove(); }
};
Iterator Iter() { return Iterator(this); }
ConstIterator ConstIter() const {
return ConstIterator(const_cast<nsTHashtable*>(this));
}
using const_iterator = ::detail::nsTHashtableEntryIterator<const EntryType>;
using iterator = ::detail::nsTHashtableEntryIterator<EntryType>;
iterator begin() { return iterator{mTable}; }
const_iterator begin() const { return const_iterator{mTable}; }
const_iterator cbegin() const { return begin(); }
iterator end() {
return iterator{mTable, typename iterator::EndIteratorTag{}};
}
const_iterator end() const {
return const_iterator{mTable, typename const_iterator::EndIteratorTag{}};
}
const_iterator cend() const { return end(); }
auto Keys() const {
return ::detail::nsTHashtableKeyRange<nsPtrHashKey<T>>{mTable};
}
void Remove(::detail::nsTHashtableKeyIterator<EntryType>& aIter) {
aIter.mIterator.Remove();
}
void SwapElements(nsTHashtable& aOther) { Base::SwapElements(aOther); }
};
#endif // nsTHashtable_h__