Split an allocation policy into an allocator and a deallocator.

src/hashmap.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 20 matching lines @@
 #include "allocation.h"
 #include "checks.h"
 #include "utils.h"
 
 namespace v8 {
 namespace internal {
 
 template<class AllocationPolicy>
 class TemplateHashMapImpl {
  public:
+  typedef typename AllocationPolicy::Alloc Allocator;
+  typedef typename AllocationPolicy::Dealloc Deallocator;
+
   typedef bool (*MatchFun) (void* key1, void* key2);
 
   // initial_capacity is the size of the initial hash map;
   // it must be a power of 2 (and thus must not be 0).
-  TemplateHashMapImpl(MatchFun match, uint32_t initial_capacity = 8);
+  TemplateHashMapImpl(MatchFun match,
+                      Allocator allocator = Allocator(),
+                      Deallocator deallocator = Deallocator(),
+                      uint32_t initial_capacity = 8);
 
   ~TemplateHashMapImpl();
 
   // HashMap entries are (key, value, hash) triplets.
   // Some clients may not need to use the value slot
   // (e.g. implementers of sets, where the key is the value).
   struct Entry {
     void* key;
     void* value;
     uint32_t hash;  // the full hash value for key
   };
 
   // If an entry with matching key is found, Lookup()
   // returns that entry. If no matching entry is found,
   // but insert is set, a new entry is inserted with
   // corresponding key, key hash, and NULL value.
   // Otherwise, NULL is returned.
-  Entry* Lookup(void* key, uint32_t hash, bool insert);
+  Entry* Lookup(void* key, uint32_t hash, bool insert,
+                Allocator allocator = Allocator());
 
   // Removes the entry with matching key.
   // It returns the value of the deleted entry
   // or null if there is no value for such key.
   void* Remove(void* key, uint32_t hash);
 
   // Empties the hash map (occupancy() == 0).
   void Clear();
 
   // The number of (non-empty) entries in the table.
@@ skipping 13 matching lines @@
   // If entries are inserted during iteration, the effect of
   // calling Next() is undefined.
   Entry* Start() const;
   Entry* Next(Entry* p) const;
 
  private:
   MatchFun match_;
   Entry* map_;
   uint32_t capacity_;
   uint32_t occupancy_;
+  Deallocator deallocator_;
 
   Entry* map_end() const { return map_ + capacity_; }
   Entry* Probe(void* key, uint32_t hash);
-  void Initialize(uint32_t capacity);
-  void Resize();
+  void Initialize(uint32_t capacity, Allocator allocator);
+  void Resize(Allocator allocator);
 };
 
 typedef TemplateHashMapImpl<FreeStoreAllocationPolicy> HashMap;
 
-template<class P>
-TemplateHashMapImpl<P>::TemplateHashMapImpl(MatchFun match,
-                    uint32_t initial_capacity) {
+template<class AllocationPolicy>
+TemplateHashMapImpl<AllocationPolicy>::TemplateHashMapImpl(
+    MatchFun match, Allocator allocator, Deallocator deallocator,
+    uint32_t initial_capacity) : deallocator_(deallocator) {
   match_ = match;
-  Initialize(initial_capacity);
+  Initialize(initial_capacity, allocator);
 }
 
 
-template<class P>
-TemplateHashMapImpl<P>::~TemplateHashMapImpl() {
-  P::Delete(map_);
+template<class AllocationPolicy>
+TemplateHashMapImpl<AllocationPolicy>::~TemplateHashMapImpl() {
+  deallocator_.Delete(map_);
 }
 
 
-template<class P>
-typename TemplateHashMapImpl<P>::Entry* TemplateHashMapImpl<P>::Lookup(
-    void* key, uint32_t hash, bool insert) {
+template<class AllocationPolicy>
+typename TemplateHashMapImpl<AllocationPolicy>::Entry*
+TemplateHashMapImpl<AllocationPolicy>::Lookup(
+    void* key, uint32_t hash, bool insert, Allocator allocator) {
   // Find a matching entry.
   Entry* p = Probe(key, hash);
   if (p->key != NULL) {
     return p;
   }
 
   // No entry found; insert one if necessary.
   if (insert) {
     p->key = key;
     p->value = NULL;
     p->hash = hash;
     occupancy_++;
 
     // Grow the map if we reached >= 80% occupancy.
     if (occupancy_ + occupancy_/4 >= capacity_) {
-      Resize();
+      Resize(allocator);
       p = Probe(key, hash);
     }
 
     return p;
   }
 
   // No entry found and none inserted.
   return NULL;
 }
 
 
-template<class P>
-void* TemplateHashMapImpl<P>::Remove(void* key, uint32_t hash) {
+template<class AllocationPolicy>
+void* TemplateHashMapImpl<AllocationPolicy>::Remove(void* key, uint32_t hash) {
   // Lookup the entry for the key to remove.
   Entry* p = Probe(key, hash);
   if (p->key == NULL) {
     // Key not found nothing to remove.
     return NULL;
   }
 
   void* value = p->value;
   // To remove an entry we need to ensure that it does not create an empty
   // entry that will cause the search for another entry to stop too soon. If all
@@ skipping 40 matching lines @@
     }
   }
 
   // Clear the entry which is allowed to en emptied.
   p->key = NULL;
   occupancy_--;
   return value;
 }
 
 
-template<class P>
-void TemplateHashMapImpl<P>::Clear() {
+template<class AllocationPolicy>
+void TemplateHashMapImpl<AllocationPolicy>::Clear() {
   // Mark all entries as empty.
   const Entry* end = map_end();
   for (Entry* p = map_; p < end; p++) {
     p->key = NULL;
   }
   occupancy_ = 0;
 }
 
 
-template<class P>
-typename TemplateHashMapImpl<P>::Entry* TemplateHashMapImpl<P>::Start() const {
+template<class AllocationPolicy>
+typename TemplateHashMapImpl<AllocationPolicy>::Entry*
+    TemplateHashMapImpl<AllocationPolicy>::Start() const {
   return Next(map_ - 1);
 }
 
 
-template<class P>
-typename TemplateHashMapImpl<P>::Entry* TemplateHashMapImpl<P>::Next(Entry* p)
-    const {
+template<class AllocationPolicy>
+typename TemplateHashMapImpl<AllocationPolicy>::Entry*
+    TemplateHashMapImpl<AllocationPolicy>::Next(Entry* p) const {
   const Entry* end = map_end();
   ASSERT(map_ - 1 <= p && p < end);
   for (p++; p < end; p++) {
     if (p->key != NULL) {
       return p;
     }
   }
   return NULL;
 }
 
 
-template<class P>
-typename TemplateHashMapImpl<P>::Entry* TemplateHashMapImpl<P>::Probe(void* key,
-                                                            uint32_t hash) {
+template<class AllocationPolicy>
+typename TemplateHashMapImpl<AllocationPolicy>::Entry*
+    TemplateHashMapImpl<AllocationPolicy>::Probe(void* key, uint32_t hash) {
   ASSERT(key != NULL);
 
   ASSERT(IsPowerOf2(capacity_));
   Entry* p = map_ + (hash & (capacity_ - 1));
   const Entry* end = map_end();
   ASSERT(map_ <= p && p < end);
 
   ASSERT(occupancy_ < capacity_);  // Guarantees loop termination.
   while (p->key != NULL && (hash != p->hash || !match_(key, p->key))) {
     p++;
     if (p >= end) {
       p = map_;
     }
   }
 
   return p;
 }
 
 
-template<class P>
-void TemplateHashMapImpl<P>::Initialize(uint32_t capacity) {
+template<class AllocationPolicy>
+void TemplateHashMapImpl<AllocationPolicy>::Initialize(uint32_t capacity,
+                                                       Allocator allocator) {
   ASSERT(IsPowerOf2(capacity));
-  map_ = reinterpret_cast<Entry*>(P::New(capacity * sizeof(Entry)));
+  map_ = reinterpret_cast<Entry*>(allocator.New(capacity * sizeof(Entry)));
   if (map_ == NULL) {
     v8::internal::FatalProcessOutOfMemory("HashMap::Initialize");
     return;
   }
   capacity_ = capacity;
   Clear();
 }
 
 
-template<class P>
-void TemplateHashMapImpl<P>::Resize() {
+template<class AllocationPolicy>
+void TemplateHashMapImpl<AllocationPolicy>::Resize(Allocator allocator) {
   Entry* map = map_;
   uint32_t n = occupancy_;
 
   // Allocate larger map.
-  Initialize(capacity_ * 2);
+  Initialize(capacity_ * 2, allocator);
 
   // Rehash all current entries.
   for (Entry* p = map; n > 0; p++) {
     if (p->key != NULL) {
       Lookup(p->key, p->hash, true)->value = p->value;
       n--;
     }
   }
 
   // Delete old map.
-  P::Delete(map);
+  deallocator_.Delete(map);
 }
 
 
 // A hash map for pointer keys and values with an STL-like interface.
 template<class Key, class Value, class AllocationPolicy>
 class TemplateHashMap: private TemplateHashMapImpl<AllocationPolicy> {
  public:
   STATIC_ASSERT(sizeof(Key*) == sizeof(void*));  // NOLINT
   STATIC_ASSERT(sizeof(Value*) == sizeof(void*));  // NOLINT
+  typedef typename AllocationPolicy::Alloc Allocator;
+  typedef typename AllocationPolicy::Dealloc Deallocator;
+
   struct value_type {
     Key* first;
     Value* second;
   };
 
   class Iterator {
    public:
     Iterator& operator++() {
       entry_ = map_->Next(entry_);
       return *this;
     }
 
     value_type* operator->() { return reinterpret_cast<value_type*>(entry_); }
     bool operator!=(const Iterator& other) { return  entry_ != other.entry_; }
 
    private:
     Iterator(const TemplateHashMapImpl<AllocationPolicy>* map,
              typename TemplateHashMapImpl<AllocationPolicy>::Entry* entry) :
         map_(map), entry_(entry) { }
 
     const TemplateHashMapImpl<AllocationPolicy>* map_;
     typename TemplateHashMapImpl<AllocationPolicy>::Entry* entry_;
 
     friend class TemplateHashMap;
   };
 
   TemplateHashMap(
-      typename TemplateHashMapImpl<AllocationPolicy>::MatchFun match)
-    : TemplateHashMapImpl<AllocationPolicy>(match) { }
+      typename TemplateHashMapImpl<AllocationPolicy>::MatchFun match,
+      Allocator allocator = Allocator(),
+      Deallocator deallocator = Deallocator())
+      : TemplateHashMapImpl<AllocationPolicy>(match, allocator, deallocator) { }
 
   Iterator begin() const { return Iterator(this, this->Start()); }
   Iterator end() const { return Iterator(this, NULL); }
   Iterator find(Key* key, bool insert = false) {
     return Iterator(this, this->Lookup(key, key->Hash(), insert));
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_HASHMAP_H_