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//===- ScopedHashTable.h - A simple scoped hash table ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements an efficient scoped hash table, which is useful for
// things like dominator-based optimizations. This allows clients to do things
// like this:
//
// ScopedHashTable<int, int> HT;
// {
// ScopedHashTableScope<int, int> Scope1(HT);
// HT.insert(0, 0);
// HT.insert(1, 1);
// {
// ScopedHashTableScope<int, int> Scope2(HT);
// HT.insert(0, 42);
// }
// }
//
// Looking up the value for "0" in the Scope2 block will return 42. Looking
// up the value for 0 before 42 is inserted or after Scope2 is popped will
// return 0.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_SCOPEDHASHTABLE_H
#define LLVM_ADT_SCOPEDHASHTABLE_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/Allocator.h"
namespace llvm {
template <typename K, typename V, typename KInfo = DenseMapInfo<K>, typename AllocatorTy = MallocAllocator> class ScopedHashTable;
template <typename K, typename V> class ScopedHashTableVal { ScopedHashTableVal *NextInScope; ScopedHashTableVal *NextForKey; K Key; V Val; ScopedHashTableVal(const K &key, const V &val) : Key(key), Val(val) {} public:
const K &getKey() const { return Key; } const V &getValue() const { return Val; } V &getValue() { return Val; }
ScopedHashTableVal *getNextForKey() { return NextForKey; } const ScopedHashTableVal *getNextForKey() const { return NextForKey; } ScopedHashTableVal *getNextInScope() { return NextInScope; } template <typename AllocatorTy> static ScopedHashTableVal *Create(ScopedHashTableVal *nextInScope, ScopedHashTableVal *nextForKey, const K &key, const V &val, AllocatorTy &Allocator) { ScopedHashTableVal *New = Allocator.template Allocate<ScopedHashTableVal>(); // Set up the value.
new (New) ScopedHashTableVal(key, val); New->NextInScope = nextInScope; New->NextForKey = nextForKey; return New; } template <typename AllocatorTy> void Destroy(AllocatorTy &Allocator) { // Free memory referenced by the item.
this->~ScopedHashTableVal(); Allocator.Deallocate(this); } };
template <typename K, typename V, typename KInfo = DenseMapInfo<K>, typename AllocatorTy = MallocAllocator> class ScopedHashTableScope { /// HT - The hashtable that we are active for.
ScopedHashTable<K, V, KInfo, AllocatorTy> &HT;
/// PrevScope - This is the scope that we are shadowing in HT.
ScopedHashTableScope *PrevScope;
/// LastValInScope - This is the last value that was inserted for this scope
/// or null if none have been inserted yet.
ScopedHashTableVal<K, V> *LastValInScope; void operator=(ScopedHashTableScope&) LLVM_DELETED_FUNCTION; ScopedHashTableScope(ScopedHashTableScope&) LLVM_DELETED_FUNCTION; public: ScopedHashTableScope(ScopedHashTable<K, V, KInfo, AllocatorTy> &HT); ~ScopedHashTableScope();
ScopedHashTableScope *getParentScope() { return PrevScope; } const ScopedHashTableScope *getParentScope() const { return PrevScope; } private: friend class ScopedHashTable<K, V, KInfo, AllocatorTy>; ScopedHashTableVal<K, V> *getLastValInScope() { return LastValInScope; } void setLastValInScope(ScopedHashTableVal<K, V> *Val) { LastValInScope = Val; } };
template <typename K, typename V, typename KInfo = DenseMapInfo<K> > class ScopedHashTableIterator { ScopedHashTableVal<K, V> *Node; public: ScopedHashTableIterator(ScopedHashTableVal<K, V> *node) : Node(node) {}
V &operator*() const { assert(Node && "Dereference end()"); return Node->getValue(); } V *operator->() const { return &Node->getValue(); }
bool operator==(const ScopedHashTableIterator &RHS) const { return Node == RHS.Node; } bool operator!=(const ScopedHashTableIterator &RHS) const { return Node != RHS.Node; }
inline ScopedHashTableIterator& operator++() { // Preincrement
assert(Node && "incrementing past end()"); Node = Node->getNextForKey(); return *this; } ScopedHashTableIterator operator++(int) { // Postincrement
ScopedHashTableIterator tmp = *this; ++*this; return tmp; } };
template <typename K, typename V, typename KInfo, typename AllocatorTy> class ScopedHashTable { public: /// ScopeTy - This is a helpful typedef that allows clients to get easy access
/// to the name of the scope for this hash table.
typedef ScopedHashTableScope<K, V, KInfo, AllocatorTy> ScopeTy; private: typedef ScopedHashTableVal<K, V> ValTy; DenseMap<K, ValTy*, KInfo> TopLevelMap; ScopeTy *CurScope; AllocatorTy Allocator; ScopedHashTable(const ScopedHashTable&); // NOT YET IMPLEMENTED
void operator=(const ScopedHashTable&); // NOT YET IMPLEMENTED
friend class ScopedHashTableScope<K, V, KInfo, AllocatorTy>; public: ScopedHashTable() : CurScope(0) {} ScopedHashTable(AllocatorTy A) : CurScope(0), Allocator(A) {} ~ScopedHashTable() { assert(CurScope == 0 && TopLevelMap.empty() && "Scope imbalance!"); }
/// Access to the allocator.
typedef typename ReferenceAdder<AllocatorTy>::result AllocatorRefTy; typedef typename ReferenceAdder<const AllocatorTy>::result AllocatorCRefTy; AllocatorRefTy getAllocator() { return Allocator; } AllocatorCRefTy getAllocator() const { return Allocator; }
bool count(const K &Key) const { return TopLevelMap.count(Key); }
V lookup(const K &Key) { typename DenseMap<K, ValTy*, KInfo>::iterator I = TopLevelMap.find(Key); if (I != TopLevelMap.end()) return I->second->getValue(); return V(); }
void insert(const K &Key, const V &Val) { insertIntoScope(CurScope, Key, Val); }
typedef ScopedHashTableIterator<K, V, KInfo> iterator;
iterator end() { return iterator(0); }
iterator begin(const K &Key) { typename DenseMap<K, ValTy*, KInfo>::iterator I = TopLevelMap.find(Key); if (I == TopLevelMap.end()) return end(); return iterator(I->second); } ScopeTy *getCurScope() { return CurScope; } const ScopeTy *getCurScope() const { return CurScope; }
/// insertIntoScope - This inserts the specified key/value at the specified
/// (possibly not the current) scope. While it is ok to insert into a scope
/// that isn't the current one, it isn't ok to insert *underneath* an existing
/// value of the specified key.
void insertIntoScope(ScopeTy *S, const K &Key, const V &Val) { assert(S && "No scope active!"); ScopedHashTableVal<K, V> *&KeyEntry = TopLevelMap[Key]; KeyEntry = ValTy::Create(S->getLastValInScope(), KeyEntry, Key, Val, Allocator); S->setLastValInScope(KeyEntry); } };
/// ScopedHashTableScope ctor - Install this as the current scope for the hash
/// table.
template <typename K, typename V, typename KInfo, typename Allocator> ScopedHashTableScope<K, V, KInfo, Allocator>:: ScopedHashTableScope(ScopedHashTable<K, V, KInfo, Allocator> &ht) : HT(ht) { PrevScope = HT.CurScope; HT.CurScope = this; LastValInScope = 0; }
template <typename K, typename V, typename KInfo, typename Allocator> ScopedHashTableScope<K, V, KInfo, Allocator>::~ScopedHashTableScope() { assert(HT.CurScope == this && "Scope imbalance!"); HT.CurScope = PrevScope;
// Pop and delete all values corresponding to this scope.
while (ScopedHashTableVal<K, V> *ThisEntry = LastValInScope) { // Pop this value out of the TopLevelMap.
if (ThisEntry->getNextForKey() == 0) { assert(HT.TopLevelMap[ThisEntry->getKey()] == ThisEntry && "Scope imbalance!"); HT.TopLevelMap.erase(ThisEntry->getKey()); } else { ScopedHashTableVal<K, V> *&KeyEntry = HT.TopLevelMap[ThisEntry->getKey()]; assert(KeyEntry == ThisEntry && "Scope imbalance!"); KeyEntry = ThisEntry->getNextForKey(); }
// Pop this value out of the scope.
LastValInScope = ThisEntry->getNextInScope();
// Delete this entry.
ThisEntry->Destroy(HT.getAllocator()); } }
} // end namespace llvm
#endif
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