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gecko-dev/js/public/HashTable.h
Terrence Cole 9cf3dabddc Bug 740153 - Don't expose Entry directly through HashMap; r=luke 
HashMap and HashSet only expose Entries through Ptr and Range, except for one
variant of put. They also don't expose the default size they use if you call
init() without an argument. These weirdnesses seem to be interface carried over
from the old jsdhash.

The first oddness is unused and can be removed, the second should simply get
exposed to make it easier to wrap HashMap and HashSet.

--HG--
extra : rebase_source : e1432a9af189229f379158ba0529956ddbf5f234
2012-03-30 11:01:58 -07:00

1397 lines
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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sw=4 et tw=99 ft=cpp:
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla SpiderMonkey JavaScript 1.9 code, released
* November 13, 2009.
*
* The Initial Developer of the Original Code is
* the Mozilla Corporation.
*
* Contributor(s):
* Brendan Eich <brendan@mozilla.org> (Original Author)
* Chris Waterson <waterson@netscape.com>
* L. David Baron <dbaron@dbaron.org>, Mozilla Corporation
* Luke Wagner <lw@mozilla.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef jshashtable_h_
#define jshashtable_h_
#include "TemplateLib.h"
#include "Utility.h"
namespace js {
class TempAllocPolicy;
/* Integral types for all hash functions. */
typedef uint32_t HashNumber;
/*****************************************************************************/
namespace detail {
template <class T, class HashPolicy, class AllocPolicy>
class HashTable;
template <class T>
class HashTableEntry {
HashNumber keyHash;
typedef typename tl::StripConst<T>::result NonConstT;
static const HashNumber sFreeKey = 0;
static const HashNumber sRemovedKey = 1;
static const HashNumber sCollisionBit = 1;
template <class, class, class> friend class HashTable;
static bool isLiveHash(HashNumber hash)
{
return hash > sRemovedKey;
}
public:
HashTableEntry() : keyHash(0), t() {}
HashTableEntry(MoveRef<HashTableEntry> rhs) : keyHash(rhs->keyHash), t(Move(rhs->t)) { }
void operator=(const HashTableEntry &rhs) { keyHash = rhs.keyHash; t = rhs.t; }
void operator=(MoveRef<HashTableEntry> rhs) { keyHash = rhs->keyHash; t = Move(rhs->t); }
NonConstT t;
bool isFree() const { return keyHash == sFreeKey; }
void setFree() { keyHash = sFreeKey; t = T(); }
bool isRemoved() const { return keyHash == sRemovedKey; }
void setRemoved() { keyHash = sRemovedKey; t = T(); }
bool isLive() const { return isLiveHash(keyHash); }
void setLive(HashNumber hn) { JS_ASSERT(isLiveHash(hn)); keyHash = hn; }
void setCollision() { JS_ASSERT(isLive()); keyHash |= sCollisionBit; }
void setCollision(HashNumber collisionBit) {
JS_ASSERT(isLive()); keyHash |= collisionBit;
}
void unsetCollision() { keyHash &= ~sCollisionBit; }
bool hasCollision() const { JS_ASSERT(isLive()); return keyHash & sCollisionBit; }
bool matchHash(HashNumber hn) { return (keyHash & ~sCollisionBit) == hn; }
HashNumber getKeyHash() const { JS_ASSERT(!hasCollision()); return keyHash; }
};
/*
* js::detail::HashTable is an implementation detail of the js::HashMap and
* js::HashSet templates. For js::Hash{Map,Set} API documentation and examples,
* skip to the end of the detail namespace.
*/
/* Reusable implementation of HashMap and HashSet. */
template <class T, class HashPolicy, class AllocPolicy>
class HashTable : private AllocPolicy
{
typedef typename tl::StripConst<T>::result NonConstT;
typedef typename HashPolicy::KeyType Key;
typedef typename HashPolicy::Lookup Lookup;
public:
typedef HashTableEntry<T> Entry;
/*
* A nullable pointer to a hash table element. A Ptr |p| can be tested
* either explicitly |if (p.found()) p->...| or using boolean conversion
* |if (p) p->...|. Ptr objects must not be used after any mutating hash
* table operations unless |generation()| is tested.
*/
class Ptr
{
friend class HashTable;
typedef void (Ptr::* ConvertibleToBool)();
void nonNull() {}
Entry *entry;
protected:
Ptr(Entry &entry) : entry(&entry) {}
public:
/* Leaves Ptr uninitialized. */
Ptr() {
#ifdef DEBUG
entry = (Entry *)0xbad;
#endif
}
bool found() const { return entry->isLive(); }
operator ConvertibleToBool() const { return found() ? &Ptr::nonNull : 0; }
bool operator==(const Ptr &rhs) const { JS_ASSERT(found() && rhs.found()); return entry == rhs.entry; }
bool operator!=(const Ptr &rhs) const { return !(*this == rhs); }
T &operator*() const { return entry->t; }
T *operator->() const { return &entry->t; }
};
/* A Ptr that can be used to add a key after a failed lookup. */
class AddPtr : public Ptr
{
friend class HashTable;
HashNumber keyHash;
DebugOnly<uint64_t> mutationCount;
AddPtr(Entry &entry, HashNumber hn) : Ptr(entry), keyHash(hn) {}
public:
/* Leaves AddPtr uninitialized. */
AddPtr() {}
};
/*
* A collection of hash table entries. The collection is enumerated by
* calling |front()| followed by |popFront()| as long as |!empty()|. As
* with Ptr/AddPtr, Range objects must not be used after any mutating hash
* table operation unless the |generation()| is tested.
*/
class Range
{
protected:
friend class HashTable;
Range(Entry *c, Entry *e) : cur(c), end(e) {
while (cur < end && !cur->isLive())
++cur;
}
Entry *cur, *end;
public:
Range() : cur(NULL), end(NULL) {}
bool empty() const {
return cur == end;
}
T &front() const {
JS_ASSERT(!empty());
return cur->t;
}
void popFront() {
JS_ASSERT(!empty());
while (++cur < end && !cur->isLive())
continue;
}
};
/*
* A Range whose lifetime delimits a mutating enumeration of a hash table.
* Since rehashing when elements were removed during enumeration would be
* bad, it is postponed until |endEnumeration()| is called. If
* |endEnumeration()| is not called before an Enum's constructor, it will
* be called automatically. Since |endEnumeration()| touches the hash
* table, the user must ensure that the hash table is still alive when this
* happens.
*/
class Enum : public Range
{
friend class HashTable;
HashTable &table;
bool added;
bool removed;
/* Not copyable. */
Enum(const Enum &);
void operator=(const Enum &);
public:
template<class Map> explicit
Enum(Map &map) : Range(map.all()), table(map.impl), added(false), removed(false) {}
/*
* Removes the |front()| element from the table, leaving |front()|
* invalid until the next call to |popFront()|. For example:
*
* HashSet<int> s;
* for (HashSet<int>::Enum e(s); !e.empty(); e.popFront())
* if (e.front() == 42)
* e.removeFront();
*/
void removeFront() {
table.remove(*this->cur);
removed = true;
}
/*
* Removes the |front()| element and re-inserts it into the table with
* a new key at the new Lookup position. |front()| is invalid after
* this operation until the next call to |popFront()|.
*/
void rekeyFront(Key &k) {
JS_ASSERT(&k != &HashPolicy::getKey(this->cur->t));
JS_ASSERT(!table.match(*this->cur, k));
Entry e = *this->cur;
HashPolicy::setKey(e.t, k);
table.remove(*this->cur);
table.add(k, e);
added = true;
}
/* Potentially rehashes the table. */
~Enum() {
if (added)
table.checkOverloaded();
if (removed)
table.checkUnderloaded();
}
/* Can be used to end the enumeration before the destructor. */
void endEnumeration() {
if (added) {
table.checkOverloaded();
added = false;
}
if (removed) {
table.checkUnderloaded();
removed = false;
}
}
};
private:
uint32_t hashShift; /* multiplicative hash shift */
uint32_t entryCount; /* number of entries in table */
uint32_t gen; /* entry storage generation number */
uint32_t removedCount; /* removed entry sentinels in table */
Entry *table; /* entry storage */
void setTableSizeLog2(unsigned sizeLog2) {
hashShift = sHashBits - sizeLog2;
}
#ifdef DEBUG
mutable struct Stats {
uint32_t searches; /* total number of table searches */
uint32_t steps; /* hash chain links traversed */
uint32_t hits; /* searches that found key */
uint32_t misses; /* searches that didn't find key */
uint32_t addOverRemoved; /* adds that recycled a removed entry */
uint32_t removes; /* calls to remove */
uint32_t removeFrees; /* calls to remove that freed the entry */
uint32_t grows; /* table expansions */
uint32_t shrinks; /* table contractions */
uint32_t compresses; /* table compressions */
} stats;
# define METER(x) x
#else
# define METER(x)
#endif
friend class js::ReentrancyGuard;
mutable DebugOnly<bool> entered;
DebugOnly<uint64_t> mutationCount;
/* The default initial capacity is 16, but you can ask for as small as 4. */
static const unsigned sMinSizeLog2 = 2;
static const unsigned sMinSize = 1 << sMinSizeLog2;
static const unsigned sDefaultInitSizeLog2 = 4;
public:
static const unsigned sDefaultInitSize = 1 << sDefaultInitSizeLog2;
private:
static const unsigned sMaxInit = JS_BIT(23);
static const unsigned sMaxCapacity = JS_BIT(24);
static const unsigned sHashBits = tl::BitSize<HashNumber>::result;
static const uint8_t sMinAlphaFrac = 64; /* (0x100 * .25) taken from jsdhash.h */
static const uint8_t sMaxAlphaFrac = 192; /* (0x100 * .75) taken from jsdhash.h */
static const uint8_t sInvMaxAlpha = 171; /* (ceil(0x100 / .75) >> 1) */
static const HashNumber sGoldenRatio = 0x9E3779B9U; /* taken from jsdhash.h */
static const HashNumber sFreeKey = Entry::sFreeKey;
static const HashNumber sRemovedKey = Entry::sRemovedKey;
static const HashNumber sCollisionBit = Entry::sCollisionBit;
static void staticAsserts()
{
/* Rely on compiler "constant overflow warnings". */
JS_STATIC_ASSERT(((sMaxInit * sInvMaxAlpha) >> 7) < sMaxCapacity);
JS_STATIC_ASSERT((sMaxCapacity * sInvMaxAlpha) <= UINT32_MAX);
JS_STATIC_ASSERT((sMaxCapacity * sizeof(Entry)) <= UINT32_MAX);
}
static bool isLiveHash(HashNumber hash)
{
return Entry::isLiveHash(hash);
}
static HashNumber prepareHash(const Lookup& l)
{
HashNumber keyHash = HashPolicy::hash(l);
/* Improve keyHash distribution. */
keyHash *= sGoldenRatio;
/* Avoid reserved hash codes. */
if (!isLiveHash(keyHash))
keyHash -= (sRemovedKey + 1);
return keyHash & ~sCollisionBit;
}
static Entry *createTable(AllocPolicy &alloc, uint32_t capacity)
{
Entry *newTable = (Entry *)alloc.malloc_(capacity * sizeof(Entry));
if (!newTable)
return NULL;
for (Entry *e = newTable, *end = e + capacity; e < end; ++e)
new(e) Entry();
return newTable;
}
static void destroyTable(AllocPolicy &alloc, Entry *oldTable, uint32_t capacity)
{
for (Entry *e = oldTable, *end = e + capacity; e < end; ++e)
e->~Entry();
alloc.free_(oldTable);
}
public:
HashTable(AllocPolicy ap)
: AllocPolicy(ap),
hashShift(sHashBits),
entryCount(0),
gen(0),
removedCount(0),
table(NULL),
entered(false),
mutationCount(0)
{}
bool init(uint32_t length)
{
/* Make sure that init isn't called twice. */
JS_ASSERT(table == NULL);
/*
* Correct for sMaxAlphaFrac such that the table will not resize
* when adding 'length' entries.
*/
if (length > sMaxInit) {
this->reportAllocOverflow();
return false;
}
uint32_t capacity = (length * sInvMaxAlpha) >> 7;
if (capacity < sMinSize)
capacity = sMinSize;
/* FIXME: use JS_CEILING_LOG2 when PGO stops crashing (bug 543034). */
uint32_t roundUp = sMinSize, roundUpLog2 = sMinSizeLog2;
while (roundUp < capacity) {
roundUp <<= 1;
++roundUpLog2;
}
capacity = roundUp;
JS_ASSERT(capacity <= sMaxCapacity);
table = createTable(*this, capacity);
if (!table)
return false;
setTableSizeLog2(roundUpLog2);
METER(memset(&stats, 0, sizeof(stats)));
return true;
}
bool initialized() const
{
return !!table;
}
~HashTable()
{
if (table)
destroyTable(*this, table, capacity());
}
private:
static HashNumber hash1(HashNumber hash0, uint32_t shift) {
return hash0 >> shift;
}
struct DoubleHash {
HashNumber h2;
HashNumber sizeMask;
};
DoubleHash hash2(HashNumber curKeyHash, uint32_t hashShift) const {
unsigned sizeLog2 = sHashBits - hashShift;
DoubleHash dh = {
((curKeyHash << sizeLog2) >> hashShift) | 1,
(HashNumber(1) << sizeLog2) - 1
};
return dh;
}
static HashNumber applyDoubleHash(HashNumber h1, const DoubleHash &dh) {
return (h1 - dh.h2) & dh.sizeMask;
}
bool overloaded() {
return entryCount + removedCount >= ((sMaxAlphaFrac * capacity()) >> 8);
}
bool underloaded() {
uint32_t tableCapacity = capacity();
return tableCapacity > sMinSize &&
entryCount <= ((sMinAlphaFrac * tableCapacity) >> 8);
}
static bool match(Entry &e, const Lookup &l) {
return HashPolicy::match(HashPolicy::getKey(e.t), l);
}
Entry &lookup(const Lookup &l, HashNumber keyHash, unsigned collisionBit) const
{
JS_ASSERT(isLiveHash(keyHash));
JS_ASSERT(!(keyHash & sCollisionBit));
JS_ASSERT(collisionBit == 0 || collisionBit == sCollisionBit);
JS_ASSERT(table);
METER(stats.searches++);
/* Compute the primary hash address. */
HashNumber h1 = hash1(keyHash, hashShift);
Entry *entry = &table[h1];
/* Miss: return space for a new entry. */
if (entry->isFree()) {
METER(stats.misses++);
return *entry;
}
/* Hit: return entry. */
if (entry->matchHash(keyHash) && match(*entry, l)) {
METER(stats.hits++);
return *entry;
}
/* Collision: double hash. */
DoubleHash dh = hash2(keyHash, hashShift);
/* Save the first removed entry pointer so we can recycle later. */
Entry *firstRemoved = NULL;
while(true) {
if (JS_UNLIKELY(entry->isRemoved())) {
if (!firstRemoved)
firstRemoved = entry;
} else {
entry->setCollision(collisionBit);
}
METER(stats.steps++);
h1 = applyDoubleHash(h1, dh);
entry = &table[h1];
if (entry->isFree()) {
METER(stats.misses++);
return firstRemoved ? *firstRemoved : *entry;
}
if (entry->matchHash(keyHash) && match(*entry, l)) {
METER(stats.hits++);
return *entry;
}
}
}
/*
* This is a copy of lookup hardcoded to the assumptions:
* 1. the lookup is a lookupForAdd
* 2. the key, whose |keyHash| has been passed is not in the table,
* 3. no entries have been removed from the table.
* This specialized search avoids the need for recovering lookup values
* from entries, which allows more flexible Lookup/Key types.
*/
Entry &findFreeEntry(HashNumber keyHash)
{
METER(stats.searches++);
JS_ASSERT(!(keyHash & sCollisionBit));
/* N.B. the |keyHash| has already been distributed. */
/* Compute the primary hash address. */
HashNumber h1 = hash1(keyHash, hashShift);
Entry *entry = &table[h1];
/* Miss: return space for a new entry. */
if (entry->isFree()) {
METER(stats.misses++);
return *entry;
}
/* Collision: double hash. */
DoubleHash dh = hash2(keyHash, hashShift);
while(true) {
JS_ASSERT(!entry->isRemoved());
entry->setCollision();
METER(stats.steps++);
h1 = applyDoubleHash(h1, dh);
entry = &table[h1];
if (entry->isFree()) {
METER(stats.misses++);
return *entry;
}
}
}
bool changeTableSize(int deltaLog2)
{
/* Look, but don't touch, until we succeed in getting new entry store. */
Entry *oldTable = table;
uint32_t oldCap = capacity();
uint32_t newLog2 = sHashBits - hashShift + deltaLog2;
uint32_t newCapacity = JS_BIT(newLog2);
if (newCapacity > sMaxCapacity) {
this->reportAllocOverflow();
return false;
}
Entry *newTable = createTable(*this, newCapacity);
if (!newTable)
return false;
/* We can't fail from here on, so update table parameters. */
setTableSizeLog2(newLog2);
removedCount = 0;
gen++;
table = newTable;
/* Copy only live entries, leaving removed ones behind. */
for (Entry *src = oldTable, *end = src + oldCap; src < end; ++src) {
if (src->isLive()) {
src->unsetCollision();
findFreeEntry(src->getKeyHash()) = Move(*src);
}
}
destroyTable(*this, oldTable, oldCap);
return true;
}
void add(const Lookup &l, const Entry &e)
{
HashNumber keyHash = prepareHash(l);
Entry &entry = lookup(l, keyHash, sCollisionBit);
if (entry.isRemoved()) {
METER(stats.addOverRemoved++);
removedCount--;
keyHash |= sCollisionBit;
}
entry.t = e.t;
entry.setLive(keyHash);
entryCount++;
mutationCount++;
}
bool checkOverloaded()
{
if (overloaded()) {
/* Compress if a quarter or more of all entries are removed. */
int deltaLog2;
if (removedCount >= (capacity() >> 2)) {
METER(stats.compresses++);
deltaLog2 = 0;
} else {
METER(stats.grows++);
deltaLog2 = 1;
}
(void) changeTableSize(deltaLog2);
return true;
}
return false;
}
void remove(Entry &e)
{
METER(stats.removes++);
if (e.hasCollision()) {
e.setRemoved();
removedCount++;
} else {
METER(stats.removeFrees++);
e.setFree();
}
entryCount--;
mutationCount++;
}
void checkUnderloaded()
{
if (underloaded()) {
METER(stats.shrinks++);
(void) changeTableSize(-1);
}
}
public:
void clear()
{
if (tl::IsPodType<Entry>::result) {
memset(table, 0, sizeof(*table) * capacity());
} else {
uint32_t tableCapacity = capacity();
for (Entry *e = table, *end = table + tableCapacity; e < end; ++e)
*e = Move(Entry());
}
removedCount = 0;
entryCount = 0;
mutationCount++;
}
void finish()
{
JS_ASSERT(!entered);
if (!table)
return;
destroyTable(*this, table, capacity());
table = NULL;
gen++;
entryCount = 0;
removedCount = 0;
mutationCount++;
}
Range all() const {
return Range(table, table + capacity());
}
bool empty() const {
return !entryCount;
}
uint32_t count() const {
return entryCount;
}
uint32_t capacity() const {
return JS_BIT(sHashBits - hashShift);
}
uint32_t generation() const {
return gen;
}
size_t sizeOfExcludingThis(JSMallocSizeOfFun mallocSizeOf) const {
return mallocSizeOf(table);
}
size_t sizeOfIncludingThis(JSMallocSizeOfFun mallocSizeOf) const {
return mallocSizeOf(this) + sizeOfExcludingThis(mallocSizeOf);
}
Ptr lookup(const Lookup &l) const {
ReentrancyGuard g(*this);
HashNumber keyHash = prepareHash(l);
return Ptr(lookup(l, keyHash, 0));
}
AddPtr lookupForAdd(const Lookup &l) const {
ReentrancyGuard g(*this);
HashNumber keyHash = prepareHash(l);
Entry &entry = lookup(l, keyHash, sCollisionBit);
AddPtr p(entry, keyHash);
p.mutationCount = mutationCount;
return p;
}
bool add(AddPtr &p)
{
ReentrancyGuard g(*this);
JS_ASSERT(mutationCount == p.mutationCount);
JS_ASSERT(table);
JS_ASSERT(!p.found());
JS_ASSERT(!(p.keyHash & sCollisionBit));
/*
* Changing an entry from removed to live does not affect whether we
* are overloaded and can be handled separately.
*/
if (p.entry->isRemoved()) {
METER(stats.addOverRemoved++);
removedCount--;
p.keyHash |= sCollisionBit;
} else {
if (checkOverloaded())
/* Preserve the validity of |p.entry|. */
p.entry = &findFreeEntry(p.keyHash);
}
p.entry->setLive(p.keyHash);
entryCount++;
mutationCount++;
return true;
}
/*
* There is an important contract between the caller and callee for this
* function: if add() returns true, the caller must assign the T value
* which produced p before using the hashtable again.
*/
bool add(AddPtr &p, T** pentry)
{
if (!add(p))
return false;
*pentry = &p.entry->t;
return true;
}
bool add(AddPtr &p, const T &t)
{
if (!add(p))
return false;
p.entry->t = t;
return true;
}
bool relookupOrAdd(AddPtr& p, const Lookup &l, const T& t)
{
p.mutationCount = mutationCount;
{
ReentrancyGuard g(*this);
p.entry = &lookup(l, p.keyHash, sCollisionBit);
}
return p.found() || add(p, t);
}
void remove(Ptr p)
{
ReentrancyGuard g(*this);
JS_ASSERT(p.found());
remove(*p.entry);
checkUnderloaded();
}
#undef METER
};
} /* namespace detail */
/*****************************************************************************/
/*
* Hash policy
*
* A hash policy P for a hash table with key-type Key must provide:
* - a type |P::Lookup| to use to lookup table entries;
* - a static member function |P::hash| with signature
*
* static js::HashNumber hash(Lookup)
*
* to use to hash the lookup type; and
* - a static member function |P::match| with signature
*
* static bool match(Key, Lookup)
*
* to use to test equality of key and lookup values.
*
* Normally, Lookup = Key. In general, though, different values and types of
* values can be used to lookup and store. If a Lookup value |l| is != to the
* added Key value |k|, the user must ensure that |P::match(k,l)|. E.g.:
*
* js::HashSet<Key, P>::AddPtr p = h.lookup(l);
* if (!p) {
* assert(P::match(k, l)); // must hold
* h.add(p, k);
* }
*/
/* Default hashing policies. */
template <class Key>
struct DefaultHasher
{
typedef Key Lookup;
static HashNumber hash(const Lookup &l) {
/* Hash if can implicitly cast to hash number type. */
return l;
}
static bool match(const Key &k, const Lookup &l) {
/* Use builtin or overloaded operator==. */
return k == l;
}
};
/*
* Pointer hashing policy that strips the lowest zeroBits when calculating the
* hash to improve key distribution.
*/
template <typename Key, size_t zeroBits>
struct PointerHasher
{
typedef Key Lookup;
static HashNumber hash(const Lookup &l) {
size_t word = reinterpret_cast<size_t>(l) >> zeroBits;
JS_STATIC_ASSERT(sizeof(HashNumber) == 4);
#if JS_BYTES_PER_WORD == 4
return HashNumber(word);
#else
JS_STATIC_ASSERT(sizeof word == 8);
return HashNumber((word >> 32) ^ word);
#endif
}
static bool match(const Key &k, const Lookup &l) {
return k == l;
}
};
template <typename Key, size_t zeroBits>
struct TaggedPointerHasher
{
typedef Key Lookup;
static HashNumber hash(const Lookup &l) {
return PointerHasher<Key, zeroBits>::hash(l);
}
static const uintptr_t COMPARE_MASK = uintptr_t(-1) - 1;
static bool match(const Key &k, const Lookup &l) {
return (uintptr_t(k) & COMPARE_MASK) == uintptr_t(l);
}
};
/*
* Specialized hashing policy for pointer types. It assumes that the type is
* at least word-aligned. For types with smaller size use PointerHasher.
*/
template <class T>
struct DefaultHasher<T *>: PointerHasher<T *, tl::FloorLog2<sizeof(void *)>::result> { };
/* Looking for a hasher for jsid? Try the DefaultHasher<jsid> in jsatom.h. */
template <class Key, class Value>
class HashMapEntry
{
template <class, class, class> friend class detail::HashTable;
template <class> friend class detail::HashTableEntry;
void operator=(const HashMapEntry &rhs) {
const_cast<Key &>(key) = rhs.key;
value = rhs.value;
}
public:
HashMapEntry() : key(), value() {}
template<typename KeyInput, typename ValueInput>
HashMapEntry(const KeyInput &k, const ValueInput &v) : key(k), value(v) {}
HashMapEntry(MoveRef<HashMapEntry> rhs)
: key(Move(rhs->key)), value(Move(rhs->value)) { }
void operator=(MoveRef<HashMapEntry> rhs) {
const_cast<Key &>(key) = Move(rhs->key);
value = Move(rhs->value);
}
const Key key;
Value value;
};
namespace tl {
template <class T>
struct IsPodType<detail::HashTableEntry<T> > {
static const bool result = IsPodType<T>::result;
};
template <class K, class V>
struct IsPodType<HashMapEntry<K, V> >
{
static const bool result = IsPodType<K>::result && IsPodType<V>::result;
};
} /* namespace tl */
/*
* JS-friendly, STL-like container providing a hash-based map from keys to
* values. In particular, HashMap calls constructors and destructors of all
* objects added so non-PODs may be used safely.
*
* Key/Value requirements:
* - default constructible, copyable, destructible, assignable
* HashPolicy requirements:
* - see "Hash policy" above (default js::DefaultHasher<Key>)
* AllocPolicy:
* - see "Allocation policies" in jsalloc.h
*
* N.B: HashMap is not reentrant: Key/Value/HashPolicy/AllocPolicy members
* called by HashMap must not call back into the same HashMap object.
* N.B: Due to the lack of exception handling, the user must call |init()|.
*/
template <class Key,
class Value,
class HashPolicy = DefaultHasher<Key>,
class AllocPolicy = TempAllocPolicy>
class HashMap
{
public:
typedef typename HashPolicy::Lookup Lookup;
typedef HashMapEntry<Key, Value> Entry;
private:
/* Implement HashMap using HashTable. Lift |Key| operations to |Entry|. */
struct MapHashPolicy : HashPolicy
{
typedef Key KeyType;
static const Key &getKey(Entry &e) { return e.key; }
static void setKey(Entry &e, Key &k) { const_cast<Key &>(e.key) = k; }
};
typedef detail::HashTable<Entry, MapHashPolicy, AllocPolicy> Impl;
friend class Impl::Enum;
/* Not implicitly copyable (expensive). May add explicit |clone| later. */
HashMap(const HashMap &);
HashMap &operator=(const HashMap &);
Impl impl;
public:
const static unsigned sDefaultInitSize = Impl::sDefaultInitSize;
/*
* HashMap construction is fallible (due to OOM); thus the user must call
* init after constructing a HashMap and check the return value.
*/
HashMap(AllocPolicy a = AllocPolicy()) : impl(a) {}
bool init(uint32_t len = sDefaultInitSize) { return impl.init(len); }
bool initialized() const { return impl.initialized(); }
/*
* Return whether the given lookup value is present in the map. E.g.:
*
* typedef HashMap<int,char> HM;
* HM h;
* if (HM::Ptr p = h.lookup(3)) {
* const HM::Entry &e = *p; // p acts like a pointer to Entry
* assert(p->key == 3); // Entry contains the key
* char val = p->value; // and value
* }
*
* Also see the definition of Ptr in HashTable above (with T = Entry).
*/
typedef typename Impl::Ptr Ptr;
Ptr lookup(const Lookup &l) const { return impl.lookup(l); }
/* Assuming |p.found()|, remove |*p|. */
void remove(Ptr p) { impl.remove(p); }
/*
* Like |lookup(l)|, but on miss, |p = lookupForAdd(l)| allows efficient
* insertion of Key |k| (where |HashPolicy::match(k,l) == true|) using
* |add(p,k,v)|. After |add(p,k,v)|, |p| points to the new Entry. E.g.:
*
* typedef HashMap<int,char> HM;
* HM h;
* HM::AddPtr p = h.lookupForAdd(3);
* if (!p) {
* if (!h.add(p, 3, 'a'))
* return false;
* }
* const HM::Entry &e = *p; // p acts like a pointer to Entry
* assert(p->key == 3); // Entry contains the key
* char val = p->value; // and value
*
* Also see the definition of AddPtr in HashTable above (with T = Entry).
*
* N.B. The caller must ensure that no mutating hash table operations
* occur between a pair of |lookupForAdd| and |add| calls. To avoid
* looking up the key a second time, the caller may use the more efficient
* relookupOrAdd method. This method reuses part of the hashing computation
* to more efficiently insert the key if it has not been added. For
* example, a mutation-handling version of the previous example:
*
* HM::AddPtr p = h.lookupForAdd(3);
* if (!p) {
* call_that_may_mutate_h();
* if (!h.relookupOrAdd(p, 3, 'a'))
* return false;
* }
* const HM::Entry &e = *p;
* assert(p->key == 3);
* char val = p->value;
*/
typedef typename Impl::AddPtr AddPtr;
AddPtr lookupForAdd(const Lookup &l) const {
return impl.lookupForAdd(l);
}
template<typename KeyInput, typename ValueInput>
bool add(AddPtr &p, const KeyInput &k, const ValueInput &v) {
Entry *pentry;
if (!impl.add(p, &pentry))
return false;
const_cast<Key &>(pentry->key) = k;
pentry->value = v;
return true;
}
bool add(AddPtr &p, const Key &k, MoveRef<Value> v) {
Entry *pentry;
if (!impl.add(p, &pentry))
return false;
const_cast<Key &>(pentry->key) = k;
pentry->value = v;
return true;
}
bool add(AddPtr &p, const Key &k) {
Entry *pentry;
if (!impl.add(p, &pentry))
return false;
const_cast<Key &>(pentry->key) = k;
return true;
}
template<typename KeyInput, typename ValueInput>
bool relookupOrAdd(AddPtr &p, const KeyInput &k, const ValueInput &v) {
return impl.relookupOrAdd(p, k, Entry(k, v));
}
/*
* |all()| returns a Range containing |count()| elements. E.g.:
*
* typedef HashMap<int,char> HM;
* HM h;
* for (HM::Range r = h.all(); !r.empty(); r.popFront())
* char c = r.front().value;
*
* Also see the definition of Range in HashTable above (with T = Entry).
*/
typedef typename Impl::Range Range;
Range all() const { return impl.all(); }
uint32_t count() const { return impl.count(); }
size_t capacity() const { return impl.capacity(); }
size_t sizeOfExcludingThis(JSMallocSizeOfFun mallocSizeOf) const {
return impl.sizeOfExcludingThis(mallocSizeOf);
}
size_t sizeOfIncludingThis(JSMallocSizeOfFun mallocSizeOf) const {
/*
* Don't just call |impl.sizeOfExcludingThis()| because there's no
* guarantee that |impl| is the first field in HashMap.
*/
return mallocSizeOf(this) + impl.sizeOfExcludingThis(mallocSizeOf);
}
/*
* Typedef for the enumeration class. An Enum may be used to examine and
* remove table entries:
*
* typedef HashMap<int,char> HM;
* HM s;
* for (HM::Enum e(s); !e.empty(); e.popFront())
* if (e.front().value == 'l')
* e.removeFront();
*
* Table resize may occur in Enum's destructor. Also see the definition of
* Enum in HashTable above (with T = Entry).
*/
typedef typename Impl::Enum Enum;
/*
* Remove all entries. This does not shrink the table. For that consider
* using the finish() method.
*/
void clear() { impl.clear(); }
/*
* Remove all the entries and release all internal buffers. The map must
* be initialized again before any use.
*/
void finish() { impl.finish(); }
/* Does the table contain any entries? */
bool empty() const { return impl.empty(); }
/*
* If |generation()| is the same before and after a HashMap operation,
* pointers into the table remain valid.
*/
unsigned generation() const { return impl.generation(); }
/* Shorthand operations: */
bool has(const Lookup &l) const {
return impl.lookup(l) != NULL;
}
/* Overwrite existing value with v. Return NULL on oom. */
template<typename KeyInput, typename ValueInput>
bool put(const KeyInput &k, const ValueInput &v) {
AddPtr p = lookupForAdd(k);
if (p) {
p->value = v;
return true;
}
return add(p, k, v);
}
/* Like put, but assert that the given key is not already present. */
bool putNew(const Key &k, const Value &v) {
AddPtr p = lookupForAdd(k);
JS_ASSERT(!p);
return add(p, k, v);
}
/* Add (k,defaultValue) if k no found. Return false-y Ptr on oom. */
Ptr lookupWithDefault(const Key &k, const Value &defaultValue) {
AddPtr p = lookupForAdd(k);
if (p)
return p;
(void)add(p, k, defaultValue); /* p is left false-y on oom. */
return p;
}
/* Remove if present. */
void remove(const Lookup &l) {
if (Ptr p = lookup(l))
remove(p);
}
};
/*
* JS-friendly, STL-like container providing a hash-based set of values. In
* particular, HashSet calls constructors and destructors of all objects added
* so non-PODs may be used safely.
*
* T requirements:
* - default constructible, copyable, destructible, assignable
* HashPolicy requirements:
* - see "Hash policy" above (default js::DefaultHasher<Key>)
* AllocPolicy:
* - see "Allocation policies" in jsalloc.h
*
* N.B: HashSet is not reentrant: T/HashPolicy/AllocPolicy members called by
* HashSet must not call back into the same HashSet object.
* N.B: Due to the lack of exception handling, the user must call |init()|.
*/
template <class T, class HashPolicy = DefaultHasher<T>, class AllocPolicy = TempAllocPolicy>
class HashSet
{
typedef typename HashPolicy::Lookup Lookup;
/* Implement HashSet in terms of HashTable. */
struct SetOps : HashPolicy {
typedef T KeyType;
static const KeyType &getKey(const T &t) { return t; }
static void setKey(T &t, KeyType &k) { t = k; }
};
typedef detail::HashTable<const T, SetOps, AllocPolicy> Impl;
friend class Impl::Enum;
/* Not implicitly copyable (expensive). May add explicit |clone| later. */
HashSet(const HashSet &);
HashSet &operator=(const HashSet &);
Impl impl;
public:
const static unsigned sDefaultInitSize = Impl::sDefaultInitSize;
/*
* HashSet construction is fallible (due to OOM); thus the user must call
* init after constructing a HashSet and check the return value.
*/
HashSet(AllocPolicy a = AllocPolicy()) : impl(a) {}
bool init(uint32_t len = sDefaultInitSize) { return impl.init(len); }
bool initialized() const { return impl.initialized(); }
/*
* Return whether the given lookup value is present in the map. E.g.:
*
* typedef HashSet<int> HS;
* HS h;
* if (HS::Ptr p = h.lookup(3)) {
* assert(*p == 3); // p acts like a pointer to int
* }
*
* Also see the definition of Ptr in HashTable above.
*/
typedef typename Impl::Ptr Ptr;
Ptr lookup(const Lookup &l) const { return impl.lookup(l); }
/* Assuming |p.found()|, remove |*p|. */
void remove(Ptr p) { impl.remove(p); }
/*
* Like |lookup(l)|, but on miss, |p = lookupForAdd(l)| allows efficient
* insertion of T value |t| (where |HashPolicy::match(t,l) == true|) using
* |add(p,t)|. After |add(p,t)|, |p| points to the new element. E.g.:
*
* typedef HashSet<int> HS;
* HS h;
* HS::AddPtr p = h.lookupForAdd(3);
* if (!p) {
* if (!h.add(p, 3))
* return false;
* }
* assert(*p == 3); // p acts like a pointer to int
*
* Also see the definition of AddPtr in HashTable above.
*
* N.B. The caller must ensure that no mutating hash table operations
* occur between a pair of |lookupForAdd| and |add| calls. To avoid
* looking up the key a second time, the caller may use the more efficient
* relookupOrAdd method. This method reuses part of the hashing computation
* to more efficiently insert the key if it has not been added. For
* example, a mutation-handling version of the previous example:
*
* HS::AddPtr p = h.lookupForAdd(3);
* if (!p) {
* call_that_may_mutate_h();
* if (!h.relookupOrAdd(p, 3, 3))
* return false;
* }
* assert(*p == 3);
*
* Note that relookupOrAdd(p,l,t) performs Lookup using l and adds the
* entry t, where the caller ensures match(l,t).
*/
typedef typename Impl::AddPtr AddPtr;
AddPtr lookupForAdd(const Lookup &l) const {
return impl.lookupForAdd(l);
}
bool add(AddPtr &p, const T &t) {
return impl.add(p, t);
}
bool relookupOrAdd(AddPtr &p, const Lookup &l, const T &t) {
return impl.relookupOrAdd(p, l, t);
}
/*
* |all()| returns a Range containing |count()| elements:
*
* typedef HashSet<int> HS;
* HS h;
* for (HS::Range r = h.all(); !r.empty(); r.popFront())
* int i = r.front();
*
* Also see the definition of Range in HashTable above.
*/
typedef typename Impl::Range Range;
Range all() const { return impl.all(); }
uint32_t count() const { return impl.count(); }
size_t capacity() const { return impl.capacity(); }
size_t sizeOfExcludingThis(JSMallocSizeOfFun mallocSizeOf) const {
return impl.sizeOfExcludingThis(mallocSizeOf);
}
size_t sizeOfIncludingThis(JSMallocSizeOfFun mallocSizeOf) const {
/*
* Don't just call |impl.sizeOfExcludingThis()| because there's no
* guarantee that |impl| is the first field in HashSet.
*/
return mallocSizeOf(this) + impl.sizeOfExcludingThis(mallocSizeOf);
}
/*
* Typedef for the enumeration class. An Enum may be used to examine and
* remove table entries:
*
* typedef HashSet<int> HS;
* HS s;
* for (HS::Enum e(s); !e.empty(); e.popFront())
* if (e.front() == 42)
* e.removeFront();
*
* Table resize may occur in Enum's destructor. Also see the definition of
* Enum in HashTable above.
*/
typedef typename Impl::Enum Enum;
/*
* Remove all entries. This does not shrink the table. For that consider
* using the finish() method.
*/
void clear() { impl.clear(); }
/*
* Remove all the entries and release all internal buffers. The set must
* be initialized again before any use.
*/
void finish() { impl.finish(); }
/* Does the table contain any entries? */
bool empty() const { return impl.empty(); }
/*
* If |generation()| is the same before and after a HashSet operation,
* pointers into the table remain valid.
*/
unsigned generation() const { return impl.generation(); }
/* Shorthand operations: */
bool has(const Lookup &l) const {
return impl.lookup(l) != NULL;
}
/* Overwrite existing value with v. Return false on oom. */
bool put(const T &t) {
AddPtr p = lookupForAdd(t);
return p ? true : add(p, t);
}
/* Like put, but assert that the given key is not already present. */
bool putNew(const T &t) {
AddPtr p = lookupForAdd(t);
JS_ASSERT(!p);
return add(p, t);
}
bool putNew(const Lookup &l, const T &t) {
AddPtr p = lookupForAdd(l);
JS_ASSERT(!p);
return add(p, t);
}
void remove(const Lookup &l) {
if (Ptr p = lookup(l))
remove(p);
}
};
} /* namespace js */
#endif
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