//===- StringMap.h - String Hash table map interface ------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file defines the StringMap class.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_STRINGMAP_H
#define LLVM_ADT_STRINGMAP_H
#include "llvm/ADT/StringMapEntry.h"
#include "llvm/ADT/iterator.h"
#include "llvm/Support/AllocatorBase.h"
#include "llvm/Support/PointerLikeTypeTraits.h"
#include <initializer_list>
#include <iterator>
namespace llvm {
template <typename ValueTy> class StringMapConstIterator;
template <typename ValueTy> class StringMapIterator;
template <typename ValueTy> class StringMapKeyIterator;
/// StringMapImpl - This is the base class of StringMap that is shared among
/// all of its instantiations.
class StringMapImpl {
protected:
// Array of NumBuckets pointers to entries, null pointers are holes.
// TheTable[NumBuckets] contains a sentinel value for easy iteration. Followed
// by an array of the actual hash values as unsigned integers.
StringMapEntryBase **TheTable = nullptr;
unsigned NumBuckets = 0;
unsigned NumItems = 0;
unsigned NumTombstones = 0;
unsigned ItemSize;
protected:
explicit StringMapImpl(unsigned itemSize) : ItemSize(itemSize) {}
StringMapImpl(StringMapImpl &&RHS)
: TheTable(RHS.TheTable), NumBuckets(RHS.NumBuckets),
NumItems(RHS.NumItems), NumTombstones(RHS.NumTombstones),
ItemSize(RHS.ItemSize) {
RHS.TheTable = nullptr;
RHS.NumBuckets = 0;
RHS.NumItems = 0;
RHS.NumTombstones = 0;
}
StringMapImpl(unsigned InitSize, unsigned ItemSize);
unsigned RehashTable(unsigned BucketNo = 0);
/// LookupBucketFor - Look up the bucket that the specified string should end
/// up in. If it already exists as a key in the map, the Item pointer for the
/// specified bucket will be non-null. Otherwise, it will be null. In either
/// case, the FullHashValue field of the bucket will be set to the hash value
/// of the string.
unsigned LookupBucketFor(StringRef Key);
/// FindKey - Look up the bucket that contains the specified key. If it exists
/// in the map, return the bucket number of the key. Otherwise return -1.
/// This does not modify the map.
int FindKey(StringRef Key) const;
/// RemoveKey - Remove the specified StringMapEntry from the table, but do not
/// delete it. This aborts if the value isn't in the table.
void RemoveKey(StringMapEntryBase *V);
/// RemoveKey - Remove the StringMapEntry for the specified key from the
/// table, returning it. If the key is not in the table, this returns null.
StringMapEntryBase *RemoveKey(StringRef Key);
/// Allocate the table with the specified number of buckets and otherwise
/// setup the map as empty.
void init(unsigned Size);
public:
static constexpr uintptr_t TombstoneIntVal =
static_cast<uintptr_t>(-1)
<< PointerLikeTypeTraits<StringMapEntryBase *>::NumLowBitsAvailable;
static StringMapEntryBase *getTombstoneVal() {
return reinterpret_cast<StringMapEntryBase *>(TombstoneIntVal);
}
unsigned getNumBuckets() const { return NumBuckets; }
unsigned getNumItems() const { return NumItems; }
bool empty() const { return NumItems == 0; }
unsigned size() const { return NumItems; }
void swap(StringMapImpl &Other) {
std::swap(TheTable, Other.TheTable);
std::swap(NumBuckets, Other.NumBuckets);
std::swap(NumItems, Other.NumItems);
std::swap(NumTombstones, Other.NumTombstones);
}
};
/// StringMap - This is an unconventional map that is specialized for handling
/// keys that are "strings", which are basically ranges of bytes. This does some
/// funky memory allocation and hashing things to make it extremely efficient,
/// storing the string data *after* the value in the map.
template <typename ValueTy, typename AllocatorTy = MallocAllocator>
class StringMap : public StringMapImpl,
private detail::AllocatorHolder<AllocatorTy> {
using AllocTy = detail::AllocatorHolder<AllocatorTy>;
public:
using MapEntryTy = StringMapEntry<ValueTy>;
StringMap() : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {}
explicit StringMap(unsigned InitialSize)
: StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))) {}
explicit StringMap(AllocatorTy A)
: StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))), AllocTy(A) {}
StringMap(unsigned InitialSize, AllocatorTy A)
: StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))),
AllocTy(A) {}
StringMap(std::initializer_list<std::pair<StringRef, ValueTy>> List)
: StringMapImpl(List.size(), static_cast<unsigned>(sizeof(MapEntryTy))) {
insert(List);
}
StringMap(StringMap &&RHS)
: StringMapImpl(std::move(RHS)), AllocTy(std::move(RHS.getAllocator())) {}
StringMap(const StringMap &RHS)
: StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))),
AllocTy(RHS.getAllocator()) {
if (RHS.empty())
return;
// Allocate TheTable of the same size as RHS's TheTable, and set the
// sentinel appropriately (and NumBuckets).
init(RHS.NumBuckets);
unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1),
*RHSHashTable = (unsigned *)(RHS.TheTable + NumBuckets + 1);
NumItems = RHS.NumItems;
NumTombstones = RHS.NumTombstones;
for (unsigned I = 0, E = NumBuckets; I != E; ++I) {
StringMapEntryBase *Bucket = RHS.TheTable[I];
if (!Bucket || Bucket == getTombstoneVal()) {
TheTable[I] = Bucket;
continue;
}
TheTable[I] = MapEntryTy::create(
static_cast<MapEntryTy *>(Bucket)->getKey(), getAllocator(),
static_cast<MapEntryTy *>(Bucket)->getValue());
HashTable[I] = RHSHashTable[I];
}
// Note that here we've copied everything from the RHS into this object,
// tombstones included. We could, instead, have re-probed for each key to
// instantiate this new object without any tombstone buckets. The
// assumption here is that items are rarely deleted from most StringMaps,
// and so tombstones are rare, so the cost of re-probing for all inputs is
// not worthwhile.
}
StringMap &operator=(StringMap RHS) {
StringMapImpl::swap(RHS);
std::swap(getAllocator(), RHS.getAllocator());
return *this;
}
~StringMap() {
// Delete all the elements in the map, but don't reset the elements
// to default values. This is a copy of clear(), but avoids unnecessary
// work not required in the destructor.
if (!empty()) {
for (unsigned I = 0, E = NumBuckets; I != E; ++I) {
StringMapEntryBase *Bucket = TheTable[I];
if (Bucket && Bucket != getTombstoneVal()) {
static_cast<MapEntryTy *>(Bucket)->Destroy(getAllocator());
}
}
}
free(TheTable);
}
using AllocTy::getAllocator;
using key_type = const char *;
using mapped_type = ValueTy;
using value_type = StringMapEntry<ValueTy>;
using size_type = size_t;
using const_iterator = StringMapConstIterator<ValueTy>;
using iterator = StringMapIterator<ValueTy>;
iterator begin() { return iterator(TheTable, NumBuckets == 0); }
iterator end() { return iterator(TheTable + NumBuckets, true); }
const_iterator begin() const {
return const_iterator(TheTable, NumBuckets == 0);
}
const_iterator end() const {
return const_iterator(TheTable + NumBuckets, true);
}
iterator_range<StringMapKeyIterator<ValueTy>> keys() const {
return make_range(StringMapKeyIterator<ValueTy>(begin()),
StringMapKeyIterator<ValueTy>(end()));
}
iterator find(StringRef Key) {
int Bucket = FindKey(Key);
if (Bucket == -1)
return end();
return iterator(TheTable + Bucket, true);
}
const_iterator find(StringRef Key) const {
int Bucket = FindKey(Key);
if (Bucket == -1)
return end();
return const_iterator(TheTable + Bucket, true);
}
/// lookup - Return the entry for the specified key, or a default
/// constructed value if no such entry exists.
ValueTy lookup(StringRef Key) const {
const_iterator it = find(Key);
if (it != end())
return it->second;
return ValueTy();
}
/// Lookup the ValueTy for the \p Key, or create a default constructed value
/// if the key is not in the map.
ValueTy &operator[](StringRef Key) { return try_emplace(Key).first->second; }
/// count - Return 1 if the element is in the map, 0 otherwise.
size_type count(StringRef Key) const { return find(Key) == end() ? 0 : 1; }
template <typename InputTy>
size_type count(const StringMapEntry<InputTy> &MapEntry) const {
return count(MapEntry.getKey());
}
/// equal - check whether both of the containers are equal.
bool operator==(const StringMap &RHS) const {
if (size() != RHS.size())
return false;
for (const auto &KeyValue : *this) {
auto FindInRHS = RHS.find(KeyValue.getKey());
if (FindInRHS == RHS.end())
return false;
if (!(KeyValue.getValue() == FindInRHS->getValue()))
return false;
}
return true;
}
bool operator!=(const StringMap &RHS) const { return !(*this == RHS); }
/// insert - Insert the specified key/value pair into the map. If the key
/// already exists in the map, return false and ignore the request, otherwise
/// insert it and return true.
bool insert(MapEntryTy *KeyValue) {
unsigned BucketNo = LookupBucketFor(KeyValue->getKey());
StringMapEntryBase *&Bucket = TheTable[BucketNo];
if (Bucket && Bucket != getTombstoneVal())
return false; // Already exists in map.
if (Bucket == getTombstoneVal())
--NumTombstones;
Bucket = KeyValue;
++NumItems;
assert(NumItems + NumTombstones <= NumBuckets);
RehashTable();
return true;
}
/// insert - Inserts the specified key/value pair into the map if the key
/// isn't already in the map. The bool component of the returned pair is true
/// if and only if the insertion takes place, and the iterator component of
/// the pair points to the element with key equivalent to the key of the pair.
std::pair<iterator, bool> insert(std::pair<StringRef, ValueTy> KV) {
return try_emplace(KV.first, std::move(KV.second));
}
/// Inserts elements from range [first, last). If multiple elements in the
/// range have keys that compare equivalent, it is unspecified which element
/// is inserted .
template <typename InputIt> void insert(InputIt First, InputIt Last) {
for (InputIt It = First; It != Last; ++It)
insert(*It);
}
/// Inserts elements from initializer list ilist. If multiple elements in
/// the range have keys that compare equivalent, it is unspecified which
/// element is inserted
void insert(std::initializer_list<std::pair<StringRef, ValueTy>> List) {
insert(List.begin(), List.end());
}
/// Inserts an element or assigns to the current element if the key already
/// exists. The return type is the same as try_emplace.
template <typename V>
std::pair<iterator, bool> insert_or_assign(StringRef Key, V &&Val) {
auto Ret = try_emplace(Key, std::forward<V>(Val));
if (!Ret.second)
Ret.first->second = std::forward<V>(Val);
return Ret;
}
/// Emplace a new element for the specified key into the map if the key isn't
/// already in the map. The bool component of the returned pair is true
/// if and only if the insertion takes place, and the iterator component of
/// the pair points to the element with key equivalent to the key of the pair.
template <typename... ArgsTy>
std::pair<iterator, bool> try_emplace(StringRef Key, ArgsTy &&...Args) {
unsigned BucketNo = LookupBucketFor(Key);
StringMapEntryBase *&Bucket = TheTable[BucketNo];
if (Bucket && Bucket != getTombstoneVal())
return std::make_pair(iterator(TheTable + BucketNo, false),
false); // Already exists in map.
if (Bucket == getTombstoneVal())
--NumTombstones;
Bucket =
MapEntryTy::create(Key, getAllocator(), std::forward<ArgsTy>(Args)...);
++NumItems;
assert(NumItems + NumTombstones <= NumBuckets);
BucketNo = RehashTable(BucketNo);
return std::make_pair(iterator(TheTable + BucketNo, false), true);
}
// clear - Empties out the StringMap
void clear() {
if (empty())
return;
// Zap all values, resetting the keys back to non-present (not tombstone),
// which is safe because we're removing all elements.
for (unsigned I = 0, E = NumBuckets; I != E; ++I) {
StringMapEntryBase *&Bucket = TheTable[I];
if (Bucket && Bucket != getTombstoneVal()) {
static_cast<MapEntryTy *>(Bucket)->Destroy(getAllocator());
}
Bucket = nullptr;
}
NumItems = 0;
NumTombstones = 0;
}
/// remove - Remove the specified key/value pair from the map, but do not
/// erase it. This aborts if the key is not in the map.
void remove(MapEntryTy *KeyValue) { RemoveKey(KeyValue); }
void erase(iterator I) {
MapEntryTy &V = *I;
remove(&V);
V.Destroy(getAllocator());
}
bool erase(StringRef Key) {
iterator I = find(Key);
if (I == end())
return false;
erase(I);
return true;
}
};
template <typename DerivedTy, typename ValueTy>
class StringMapIterBase
: public iterator_facade_base<DerivedTy, std::forward_iterator_tag,
ValueTy> {
protected:
StringMapEntryBase **Ptr = nullptr;
public:
StringMapIterBase() = default;
explicit StringMapIterBase(StringMapEntryBase **Bucket,
bool NoAdvance = false)
: Ptr(Bucket) {
if (!NoAdvance)
AdvancePastEmptyBuckets();
}
DerivedTy &operator=(const DerivedTy &Other) {
Ptr = Other.Ptr;
return static_cast<DerivedTy &>(*this);
}
friend bool operator==(const DerivedTy &LHS, const DerivedTy &RHS) {
return LHS.Ptr == RHS.Ptr;
}
DerivedTy &operator++() { // Preincrement
++Ptr;
AdvancePastEmptyBuckets();
return static_cast<DerivedTy &>(*this);
}
DerivedTy operator++(int) { // Post-increment
DerivedTy Tmp(Ptr);
++*this;
return Tmp;
}
private:
void AdvancePastEmptyBuckets() {
while (*Ptr == nullptr || *Ptr == StringMapImpl::getTombstoneVal())
++Ptr;
}
};
template <typename ValueTy>
class StringMapConstIterator
: public StringMapIterBase<StringMapConstIterator<ValueTy>,
const StringMapEntry<ValueTy>> {
using base = StringMapIterBase<StringMapConstIterator<ValueTy>,
const StringMapEntry<ValueTy>>;
public:
StringMapConstIterator() = default;
explicit StringMapConstIterator(StringMapEntryBase **Bucket,
bool NoAdvance = false)
: base(Bucket, NoAdvance) {}
const StringMapEntry<ValueTy> &operator*() const {
return *static_cast<const StringMapEntry<ValueTy> *>(*this->Ptr);
}
};
template <typename ValueTy>
class StringMapIterator : public StringMapIterBase<StringMapIterator<ValueTy>,
StringMapEntry<ValueTy>> {
using base =
StringMapIterBase<StringMapIterator<ValueTy>, StringMapEntry<ValueTy>>;
public:
StringMapIterator() = default;
explicit StringMapIterator(StringMapEntryBase **Bucket,
bool NoAdvance = false)
: base(Bucket, NoAdvance) {}
StringMapEntry<ValueTy> &operator*() const {
return *static_cast<StringMapEntry<ValueTy> *>(*this->Ptr);
}
operator StringMapConstIterator<ValueTy>() const {
return StringMapConstIterator<ValueTy>(this->Ptr, true);
}
};
template <typename ValueTy>
class StringMapKeyIterator
: public iterator_adaptor_base<StringMapKeyIterator<ValueTy>,
StringMapConstIterator<ValueTy>,
std::forward_iterator_tag, StringRef> {
using base = iterator_adaptor_base<StringMapKeyIterator<ValueTy>,
StringMapConstIterator<ValueTy>,
std::forward_iterator_tag, StringRef>;
public:
StringMapKeyIterator() = default;
explicit StringMapKeyIterator(StringMapConstIterator<ValueTy> Iter)
: base(std::move(Iter)) {}
StringRef operator*() const { return this->wrapped()->getKey(); }
};
} // end namespace llvm
#endif // LLVM_ADT_STRINGMAP_H