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// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#ifndef RUNTIME_VM_HASH_TABLE_H_
#define RUNTIME_VM_HASH_TABLE_H_
#include "platform/assert.h"
#include "vm/object.h"
namespace dart {
// OVERVIEW:
//
// Hash maps and hash sets all use RawArray as backing storage. At the lowest
// level is a generic open-addressing table that supports deletion.
// - HashTable
// The next layer provides ordering and iteration functionality:
// - UnorderedHashTable
// - LinkedListHashTable (TODO(koda): Implement.)
// The utility class HashTables handles growth and conversion.
// The next layer fixes the payload size and provides a natural interface:
// - HashMap
// - HashSet
// Combining either of these with an iteration strategy, we get the templates
// intended for use outside this file:
// - UnorderedHashMap
// - LinkedListHashMap
// - UnorderedHashSet
// - LinkedListHashSet
// Each of these can be finally specialized with KeyTraits to support any set of
// lookup key types (e.g., look up a char* in a set of String objects), and
// any equality and hash code computation.
//
// The classes all wrap an Array handle, and methods like HashSet::Insert can
// trigger growth into a new RawArray, updating the handle. Debug mode asserts
// that 'Release' was called once to access the final array before destruction.
// NOTE: The handle returned by 'Release' is cleared by ~HashTable.
//
// Example use:
// typedef UnorderedHashMap<FooTraits> FooMap;
// ...
// FooMap cache(get_foo_cache());
// cache.UpdateOrInsert(name0, obj0);
// cache.UpdateOrInsert(name1, obj1);
// ...
// set_foo_cache(cache.Release());
//
// If you *know* that no mutating operations were called, you can optimize:
// ...
// obj ^= cache.GetOrNull(name);
// ASSERT(cache.Release().raw() == get_foo_cache());
//
// TODO(koda): When exposing these to Dart code, document and assert that
// KeyTraits methods must not run Dart code (since the C++ code doesn't check
// for concurrent modification).
// Open-addressing hash table template using a RawArray as backing storage.
//
// The elements of the array are partitioned into entries:
// [ header | metadata | entry0 | entry1 | ... | entryN ]
// Each entry contains a key, followed by zero or more payload components,
// and has 3 possible states: unused, occupied, or deleted.
// The header tracks the number of entries in each state.
// Any object except the backing storage array and Object::transition_sentinel()
// may be stored as a key. Any object may be stored in a payload.
//
// Parameters
// KeyTraits: defines static methods
// bool IsMatch(const Key& key, const Object& obj) and
// uword Hash(const Key& key) for any number of desired lookup key types.
// kPayloadSize: number of components of the payload in each entry.
// kMetaDataSize: number of elements reserved (e.g., for iteration order data).
template <typename KeyTraits, intptr_t kPayloadSize, intptr_t kMetaDataSize>
class HashTable : public ValueObject {
public:
typedef KeyTraits Traits;
// Uses the passed in handles for all handle operations.
// 'Release' must be called at the end to obtain the final table
// after potential growth/shrinkage.
HashTable(Object* key, Smi* index, Array* data)
: key_handle_(key),
smi_handle_(index),
data_(data),
released_data_(NULL) {}
// Uses 'zone' for handle allocation. 'Release' must be called at the end
// to obtain the final table after potential growth/shrinkage.
HashTable(Zone* zone, ArrayPtr data)
: key_handle_(&Object::Handle(zone)),
smi_handle_(&Smi::Handle(zone)),
data_(&Array::Handle(zone, data)),
released_data_(NULL) {}
// Returns the final table. The handle is cleared when this HashTable is
// destroyed.
Array& Release() {
ASSERT(data_ != NULL);
ASSERT(released_data_ == NULL);
// Ensure that no methods are called after 'Release'.
released_data_ = data_;
data_ = NULL;
return *released_data_;
}
~HashTable() {
// In DEBUG mode, calling 'Release' is mandatory.
ASSERT(data_ == NULL);
if (released_data_ != NULL) {
*released_data_ = Array::null();
}
}
// Returns a backing storage size such that 'num_occupied' distinct keys can
// be inserted into the table.
static intptr_t ArrayLengthForNumOccupied(intptr_t num_occupied) {
// Because we use quadratic (actually triangle number) probing it is
// important that the size is a power of two (otherwise we could fail to
// find an empty slot). This is described in Knuth's The Art of Computer
// Programming Volume 2, Chapter 6.4, exercise 20 (solution in the
// appendix, 2nd edition).
intptr_t num_entries = Utils::RoundUpToPowerOfTwo(num_occupied + 1);
return kFirstKeyIndex + (kEntrySize * num_entries);
}
// Initializes an empty table.
void Initialize() const {
ASSERT(data_->Length() >= ArrayLengthForNumOccupied(0));
*smi_handle_ = Smi::New(0);
data_->SetAt(kOccupiedEntriesIndex, *smi_handle_);
data_->SetAt(kDeletedEntriesIndex, *smi_handle_);
#if !defined(PRODUCT)
data_->SetAt(kNumGrowsIndex, *smi_handle_);
data_->SetAt(kNumLT5LookupsIndex, *smi_handle_);
data_->SetAt(kNumLT25LookupsIndex, *smi_handle_);
data_->SetAt(kNumGT25LookupsIndex, *smi_handle_);
data_->SetAt(kNumProbesIndex, *smi_handle_);
#endif // !defined(PRODUCT)
for (intptr_t i = kHeaderSize; i < data_->Length(); ++i) {
data_->SetAt(i, UnusedMarker());
}
}
// Returns whether 'key' matches any key in the table.
template <typename Key>
bool ContainsKey(const Key& key) const {
return FindKey(key) != -1;
}
// Returns the entry that matches 'key', or -1 if none exists.
template <typename Key>
intptr_t FindKey(const Key& key) const {
const intptr_t num_entries = NumEntries();
ASSERT(NumOccupied() < num_entries);
// TODO(koda): Add salt.
NOT_IN_PRODUCT(intptr_t collisions = 0;)
uword hash = KeyTraits::Hash(key);
ASSERT(Utils::IsPowerOfTwo(num_entries));
intptr_t probe = hash & (num_entries - 1);
int probe_distance = 1;
while (true) {
if (IsUnused(probe)) {
NOT_IN_PRODUCT(UpdateCollisions(collisions);)
return -1;
} else if (!IsDeleted(probe)) {
*key_handle_ = GetKey(probe);
if (KeyTraits::IsMatch(key, *key_handle_)) {
NOT_IN_PRODUCT(UpdateCollisions(collisions);)
return probe;
}
NOT_IN_PRODUCT(collisions += 1;)
}
// Advance probe. See ArrayLengthForNumOccupied comment for
// explanation of how we know this hits all slots.
probe = (probe + probe_distance) & (num_entries - 1);
probe_distance++;
}
UNREACHABLE();
return -1;
}
// Sets *entry to either:
// - an occupied entry matching 'key', and returns true, or
// - an unused/deleted entry where a matching key may be inserted,
// and returns false.
template <typename Key>
bool FindKeyOrDeletedOrUnused(const Key& key, intptr_t* entry) const {
const intptr_t num_entries = NumEntries();
ASSERT(entry != NULL);
ASSERT(NumOccupied() < num_entries);
NOT_IN_PRODUCT(intptr_t collisions = 0;)
uword hash = KeyTraits::Hash(key);
ASSERT(Utils::IsPowerOfTwo(num_entries));
intptr_t probe = hash & (num_entries - 1);
int probe_distance = 1;
intptr_t deleted = -1;
while (true) {
if (IsUnused(probe)) {
*entry = (deleted != -1) ? deleted : probe;
NOT_IN_PRODUCT(UpdateCollisions(collisions);)
return false;
} else if (IsDeleted(probe)) {
if (deleted == -1) {
deleted = probe;
}
} else {
*key_handle_ = GetKey(probe);
if (KeyTraits::IsMatch(key, *key_handle_)) {
*entry = probe;
NOT_IN_PRODUCT(UpdateCollisions(collisions);)
return true;
}
NOT_IN_PRODUCT(collisions += 1;)
}
// Advance probe. See ArrayLengthForNumOccupied comment for
// explanation of how we know this hits all slots.
probe = (probe + probe_distance) & (num_entries - 1);
probe_distance++;
}
UNREACHABLE();
return false;
}
// Sets the key of a previously unoccupied entry. This must not be the last
// unoccupied entry.
void InsertKey(intptr_t entry, const Object& key) const {
ASSERT(key.raw() != UnusedMarker().raw());
ASSERT(key.raw() != DeletedMarker().raw());
ASSERT(!IsOccupied(entry));
AdjustSmiValueAt(kOccupiedEntriesIndex, 1);
if (IsDeleted(entry)) {
AdjustSmiValueAt(kDeletedEntriesIndex, -1);
} else {
ASSERT(IsUnused(entry));
}
InternalSetKey(entry, key);
ASSERT(IsOccupied(entry));
ASSERT(NumOccupied() < NumEntries());
}
const Object& UnusedMarker() const { return Object::transition_sentinel(); }
const Object& DeletedMarker() const { return *data_; }
bool IsUnused(intptr_t entry) const {
return InternalGetKey(entry) == UnusedMarker().raw();
}
bool IsOccupied(intptr_t entry) const {
return !IsUnused(entry) && !IsDeleted(entry);
}
bool IsDeleted(intptr_t entry) const {
return InternalGetKey(entry) == DeletedMarker().raw();
}
ObjectPtr GetKey(intptr_t entry) const {
ASSERT(IsOccupied(entry));
return InternalGetKey(entry);
}
ObjectPtr GetPayload(intptr_t entry, intptr_t component) const {
ASSERT(IsOccupied(entry));
return data_->At(PayloadIndex(entry, component));
}
void UpdatePayload(intptr_t entry,
intptr_t component,
const Object& value) const {
ASSERT(IsOccupied(entry));
ASSERT(0 <= component && component < kPayloadSize);
data_->SetAt(PayloadIndex(entry, component), value);
}
// Deletes both the key and payload of the specified entry.
void DeleteEntry(intptr_t entry) const {
ASSERT(IsOccupied(entry));
for (intptr_t i = 0; i < kPayloadSize; ++i) {
UpdatePayload(entry, i, DeletedMarker());
}
InternalSetKey(entry, DeletedMarker());
AdjustSmiValueAt(kOccupiedEntriesIndex, -1);
AdjustSmiValueAt(kDeletedEntriesIndex, 1);
}
intptr_t NumEntries() const {
return (data_->Length() - kFirstKeyIndex) / kEntrySize;
}
intptr_t NumUnused() const {
return NumEntries() - NumOccupied() - NumDeleted();
}
intptr_t NumOccupied() const { return GetSmiValueAt(kOccupiedEntriesIndex); }
intptr_t NumDeleted() const { return GetSmiValueAt(kDeletedEntriesIndex); }
Object& KeyHandle() const { return *key_handle_; }
Smi& SmiHandle() const { return *smi_handle_; }
#if !defined(PRODUCT)
intptr_t NumGrows() const { return GetSmiValueAt(kNumGrowsIndex); }
intptr_t NumLT5Collisions() const {
return GetSmiValueAt(kNumLT5LookupsIndex);
}
intptr_t NumLT25Collisions() const {
return GetSmiValueAt(kNumLT25LookupsIndex);
}
intptr_t NumGT25Collisions() const {
return GetSmiValueAt(kNumGT25LookupsIndex);
}
intptr_t NumProbes() const { return GetSmiValueAt(kNumProbesIndex); }
void UpdateGrowth() const {
if (KeyTraits::ReportStats()) {
AdjustSmiValueAt(kNumGrowsIndex, 1);
}
}
void UpdateCollisions(intptr_t collisions) const {
if (KeyTraits::ReportStats()) {
if (data_->raw()->ptr()->InVMIsolateHeap()) {
return;
}
AdjustSmiValueAt(kNumProbesIndex, collisions + 1);
if (collisions < 5) {
AdjustSmiValueAt(kNumLT5LookupsIndex, 1);
} else if (collisions < 25) {
AdjustSmiValueAt(kNumLT25LookupsIndex, 1);
} else {
AdjustSmiValueAt(kNumGT25LookupsIndex, 1);
}
}
}
void PrintStats() const {
if (!KeyTraits::ReportStats()) {
return;
}
const intptr_t num5 = NumLT5Collisions();
const intptr_t num25 = NumLT25Collisions();
const intptr_t num_more = NumGT25Collisions();
// clang-format off
OS::PrintErr("Stats for %s table :\n"
" Size of table = %" Pd ",Number of Occupied entries = %" Pd "\n"
" Number of Grows = %" Pd "\n"
" Number of lookups with < 5 collisions = %" Pd "\n"
" Number of lookups with < 25 collisions = %" Pd "\n"
" Number of lookups with > 25 collisions = %" Pd "\n"
" Average number of probes = %g\n",
KeyTraits::Name(),
NumEntries(), NumOccupied(), NumGrows(),
num5, num25, num_more,
static_cast<double>(NumProbes()) / (num5 + num25 + num_more));
// clang-format on
}
#endif // !PRODUCT
protected:
static const intptr_t kOccupiedEntriesIndex = 0;
static const intptr_t kDeletedEntriesIndex = 1;
#if defined(PRODUCT)
static const intptr_t kHeaderSize = kDeletedEntriesIndex + 1;
#else
static const intptr_t kNumGrowsIndex = 2;
static const intptr_t kNumLT5LookupsIndex = 3;
static const intptr_t kNumLT25LookupsIndex = 4;
static const intptr_t kNumGT25LookupsIndex = 5;
static const intptr_t kNumProbesIndex = 6;
static const intptr_t kHeaderSize = kNumProbesIndex + 1;
#endif
static const intptr_t kMetaDataIndex = kHeaderSize;
static const intptr_t kFirstKeyIndex = kHeaderSize + kMetaDataSize;
static const intptr_t kEntrySize = 1 + kPayloadSize;
intptr_t KeyIndex(intptr_t entry) const {
ASSERT(0 <= entry && entry < NumEntries());
return kFirstKeyIndex + (kEntrySize * entry);
}
intptr_t PayloadIndex(intptr_t entry, intptr_t component) const {
ASSERT(0 <= component && component < kPayloadSize);
return KeyIndex(entry) + 1 + component;
}
ObjectPtr InternalGetKey(intptr_t entry) const {
return data_->At(KeyIndex(entry));
}
void InternalSetKey(intptr_t entry, const Object& key) const {
data_->SetAt(KeyIndex(entry), key);
}
intptr_t GetSmiValueAt(intptr_t index) const {
ASSERT(!data_->IsNull());
ASSERT(!data_->At(index)->IsHeapObject());
return Smi::Value(Smi::RawCast(data_->At(index)));
}
void SetSmiValueAt(intptr_t index, intptr_t value) const {
*smi_handle_ = Smi::New(value);
data_->SetAt(index, *smi_handle_);
}
void AdjustSmiValueAt(intptr_t index, intptr_t delta) const {
SetSmiValueAt(index, (GetSmiValueAt(index) + delta));
}
Object* key_handle_;
Smi* smi_handle_;
// Exactly one of these is non-NULL, depending on whether Release was called.
Array* data_;
Array* released_data_;
friend class HashTables;
};
// Table with unspecified iteration order. No payload overhead or metadata.
template <typename KeyTraits, intptr_t kUserPayloadSize>
class UnorderedHashTable : public HashTable<KeyTraits, kUserPayloadSize, 0> {
public:
typedef HashTable<KeyTraits, kUserPayloadSize, 0> BaseTable;
static const intptr_t kPayloadSize = kUserPayloadSize;
explicit UnorderedHashTable(ArrayPtr data)
: BaseTable(Thread::Current()->zone(), data) {}
UnorderedHashTable(Zone* zone, ArrayPtr data) : BaseTable(zone, data) {}
UnorderedHashTable(Object* key, Smi* value, Array* data)
: BaseTable(key, value, data) {}
// Note: Does not check for concurrent modification.
class Iterator {
public:
explicit Iterator(const UnorderedHashTable* table)
: table_(table), entry_(-1) {}
bool MoveNext() {
while (entry_ < (table_->NumEntries() - 1)) {
++entry_;
if (table_->IsOccupied(entry_)) {
return true;
}
}
return false;
}
intptr_t Current() { return entry_; }
private:
const UnorderedHashTable* table_;
intptr_t entry_;
};
// No extra book-keeping needed for Initialize, InsertKey, DeleteEntry.
};
class HashTables : public AllStatic {
public:
// Allocates and initializes a table.
template <typename Table>
static ArrayPtr New(intptr_t initial_capacity,
Heap::Space space = Heap::kNew) {
Table table(
Thread::Current()->zone(),
Array::New(Table::ArrayLengthForNumOccupied(initial_capacity), space));
table.Initialize();
return table.Release().raw();
}
template <typename Table>
static ArrayPtr New(const Array& array) {
Table table(Thread::Current()->zone(), array.raw());
table.Initialize();
return table.Release().raw();
}
// Clears 'to' and inserts all elements from 'from', in iteration order.
// The tables must have the same user payload size.
template <typename From, typename To>
static void Copy(const From& from, const To& to) {
COMPILE_ASSERT(From::kPayloadSize == To::kPayloadSize);
to.Initialize();
ASSERT(from.NumOccupied() < to.NumEntries());
typename From::Iterator it(&from);
Object& obj = Object::Handle();
while (it.MoveNext()) {
intptr_t from_entry = it.Current();
obj = from.GetKey(from_entry);
intptr_t to_entry = -1;
const Object& key = obj;
bool present = to.FindKeyOrDeletedOrUnused(key, &to_entry);
ASSERT(!present);
to.InsertKey(to_entry, obj);
for (intptr_t i = 0; i < From::kPayloadSize; ++i) {
obj = from.GetPayload(from_entry, i);
to.UpdatePayload(to_entry, i, obj);
}
}
}
template <typename Table>
static void EnsureLoadFactor(double high, const Table& table) {
// We count deleted elements because they take up space just
// like occupied slots in order to cause a rehashing.
const double current = (1 + table.NumOccupied() + table.NumDeleted()) /
static_cast<double>(table.NumEntries());
const bool too_many_deleted = table.NumOccupied() <= table.NumDeleted();
if (current < high && !too_many_deleted) {
return;
}
// Normally we double the size here, but if less than half are occupied
// then it won't grow (this would imply that there were quite a lot of
// deleted slots). We don't want to constantly rehash if we are adding
// and deleting entries at just under the load factor limit, so we may
// double the size even though the number of occupied slots would not
// necessarily justify it. For example if the max load factor is 71% and
// the table is 70% full we will double the size to avoid a rehash every
// time 1% has been added and deleted.
const intptr_t new_capacity = table.NumOccupied() * 2 + 1;
ASSERT(table.NumOccupied() == 0 ||
((1.0 + table.NumOccupied()) /
Utils::RoundUpToPowerOfTwo(new_capacity)) <= high);
Table new_table(New<Table>(new_capacity, // Is rounded up to power of 2.
table.data_->IsOld() ? Heap::kOld : Heap::kNew));
Copy(table, new_table);
*table.data_ = new_table.Release().raw();
NOT_IN_PRODUCT(table.UpdateGrowth(); table.PrintStats();)
}
// Serializes a table by concatenating its entries as an array.
template <typename Table>
static ArrayPtr ToArray(const Table& table, bool include_payload) {
const intptr_t entry_size = include_payload ? (1 + Table::kPayloadSize) : 1;
Array& result = Array::Handle(Array::New(table.NumOccupied() * entry_size));
typename Table::Iterator it(&table);
Object& obj = Object::Handle();
intptr_t result_index = 0;
while (it.MoveNext()) {
intptr_t entry = it.Current();
obj = table.GetKey(entry);
result.SetAt(result_index++, obj);
if (include_payload) {
for (intptr_t i = 0; i < Table::kPayloadSize; ++i) {
obj = table.GetPayload(entry, i);
result.SetAt(result_index++, obj);
}
}
}
return result.raw();
}
};
template <typename BaseIterTable>
class HashMap : public BaseIterTable {
public:
explicit HashMap(ArrayPtr data)
: BaseIterTable(Thread::Current()->zone(), data) {}
HashMap(Zone* zone, ArrayPtr data) : BaseIterTable(zone, data) {}
HashMap(Object* key, Smi* value, Array* data)
: BaseIterTable(key, value, data) {}
template <typename Key>
ObjectPtr GetOrNull(const Key& key, bool* present = NULL) const {
intptr_t entry = BaseIterTable::FindKey(key);
if (present != NULL) {
*present = (entry != -1);
}
return (entry == -1) ? Object::null() : BaseIterTable::GetPayload(entry, 0);
}
template <typename Key>
ObjectPtr GetOrDie(const Key& key) const {
intptr_t entry = BaseIterTable::FindKey(key);
if (entry == -1) UNREACHABLE();
return BaseIterTable::GetPayload(entry, 0);
}
bool UpdateOrInsert(const Object& key, const Object& value) const {
EnsureCapacity();
intptr_t entry = -1;
bool present = BaseIterTable::FindKeyOrDeletedOrUnused(key, &entry);
if (!present) {
BaseIterTable::InsertKey(entry, key);
}
BaseIterTable::UpdatePayload(entry, 0, value);
return present;
}
// Update the value of an existing key. Note that 'key' need not be an Object.
template <typename Key>
void UpdateValue(const Key& key, const Object& value) const {
intptr_t entry = BaseIterTable::FindKey(key);
ASSERT(entry != -1);
BaseIterTable::UpdatePayload(entry, 0, value);
}
// If 'key' is not present, maps it to 'value_if_absent'. Returns the final
// value in the map.
ObjectPtr InsertOrGetValue(const Object& key,
const Object& value_if_absent) const {
EnsureCapacity();
intptr_t entry = -1;
if (!BaseIterTable::FindKeyOrDeletedOrUnused(key, &entry)) {
BaseIterTable::InsertKey(entry, key);
BaseIterTable::UpdatePayload(entry, 0, value_if_absent);
return value_if_absent.raw();
} else {
return BaseIterTable::GetPayload(entry, 0);
}
}
// Like InsertOrGetValue, but calls NewKey to allocate a key object if needed.
template <typename Key>
ObjectPtr InsertNewOrGetValue(const Key& key,
const Object& value_if_absent) const {
EnsureCapacity();
intptr_t entry = -1;
if (!BaseIterTable::FindKeyOrDeletedOrUnused(key, &entry)) {
BaseIterTable::KeyHandle() =
BaseIterTable::BaseTable::Traits::NewKey(key);
BaseIterTable::InsertKey(entry, BaseIterTable::KeyHandle());
BaseIterTable::UpdatePayload(entry, 0, value_if_absent);
return value_if_absent.raw();
} else {
return BaseIterTable::GetPayload(entry, 0);
}
}
template <typename Key>
bool Remove(const Key& key) const {
intptr_t entry = BaseIterTable::FindKey(key);
if (entry == -1) {
return false;
} else {
BaseIterTable::DeleteEntry(entry);
return true;
}
}
void Clear() const { BaseIterTable::Initialize(); }
protected:
void EnsureCapacity() const {
static const double kMaxLoadFactor = 0.71;
HashTables::EnsureLoadFactor(kMaxLoadFactor, *this);
}
};
template <typename KeyTraits>
class UnorderedHashMap : public HashMap<UnorderedHashTable<KeyTraits, 1> > {
public:
typedef HashMap<UnorderedHashTable<KeyTraits, 1> > BaseMap;
explicit UnorderedHashMap(ArrayPtr data)
: BaseMap(Thread::Current()->zone(), data) {}
UnorderedHashMap(Zone* zone, ArrayPtr data) : BaseMap(zone, data) {}
UnorderedHashMap(Object* key, Smi* value, Array* data)
: BaseMap(key, value, data) {}
};
template <typename BaseIterTable>
class HashSet : public BaseIterTable {
public:
explicit HashSet(ArrayPtr data)
: BaseIterTable(Thread::Current()->zone(), data) {}
HashSet(Zone* zone, ArrayPtr data) : BaseIterTable(zone, data) {}
HashSet(Object* key, Smi* value, Array* data)
: BaseIterTable(key, value, data) {}
bool Insert(const Object& key) {
EnsureCapacity();
intptr_t entry = -1;
bool present = BaseIterTable::FindKeyOrDeletedOrUnused(key, &entry);
if (!present) {
BaseIterTable::InsertKey(entry, key);
}
return present;
}
// If 'key' is not present, insert and return it. Else, return the existing
// key in the set (useful for canonicalization).
ObjectPtr InsertOrGet(const Object& key) const {
EnsureCapacity();
intptr_t entry = -1;
if (!BaseIterTable::FindKeyOrDeletedOrUnused(key, &entry)) {
BaseIterTable::InsertKey(entry, key);
return key.raw();
} else {
return BaseIterTable::GetKey(entry);
}
}
// Like InsertOrGet, but calls NewKey to allocate a key object if needed.
template <typename Key>
ObjectPtr InsertNewOrGet(const Key& key) const {
EnsureCapacity();
intptr_t entry = -1;
if (!BaseIterTable::FindKeyOrDeletedOrUnused(key, &entry)) {
BaseIterTable::KeyHandle() =
BaseIterTable::BaseTable::Traits::NewKey(key);
BaseIterTable::InsertKey(entry, BaseIterTable::KeyHandle());
return BaseIterTable::KeyHandle().raw();
} else {
return BaseIterTable::GetKey(entry);
}
}
template <typename Key>
ObjectPtr GetOrNull(const Key& key, bool* present = NULL) const {
intptr_t entry = BaseIterTable::FindKey(key);
if (present != NULL) {
*present = (entry != -1);
}
return (entry == -1) ? Object::null() : BaseIterTable::GetKey(entry);
}
template <typename Key>
bool Remove(const Key& key) const {
intptr_t entry = BaseIterTable::FindKey(key);
if (entry == -1) {
return false;
} else {
BaseIterTable::DeleteEntry(entry);
return true;
}
}
void Clear() const { BaseIterTable::Initialize(); }
protected:
void EnsureCapacity() const {
static const double kMaxLoadFactor = 0.71;
HashTables::EnsureLoadFactor(kMaxLoadFactor, *this);
}
};
template <typename KeyTraits>
class UnorderedHashSet : public HashSet<UnorderedHashTable<KeyTraits, 0> > {
public:
typedef HashSet<UnorderedHashTable<KeyTraits, 0> > BaseSet;
explicit UnorderedHashSet(ArrayPtr data)
: BaseSet(Thread::Current()->zone(), data) {
ASSERT(data != Array::null());
}
UnorderedHashSet(Zone* zone, ArrayPtr data) : BaseSet(zone, data) {}
UnorderedHashSet(Object* key, Smi* value, Array* data)
: BaseSet(key, value, data) {}
void Dump() const {
Object& entry = Object::Handle();
for (intptr_t i = 0; i < this->data_->Length(); i++) {
entry = this->data_->At(i);
if (entry.raw() == BaseSet::UnusedMarker().raw() ||
entry.raw() == BaseSet::DeletedMarker().raw() || entry.IsSmi()) {
// empty, deleted, num_used/num_deleted
OS::PrintErr("%" Pd ": %s\n", i, entry.ToCString());
} else {
intptr_t hash = KeyTraits::Hash(entry);
OS::PrintErr("%" Pd ": %" Pd ", %s\n", i, hash, entry.ToCString());
}
}
}
};
} // namespace dart
#endif // RUNTIME_VM_HASH_TABLE_H_