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// Copyright (c) 2012, 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_PLATFORM_HASHMAP_H_
#define RUNTIME_PLATFORM_HASHMAP_H_
#include "platform/globals.h"
namespace dart {
class SimpleHashMap {
public:
typedef bool (*MatchFun)(void* key1, void* key2);
typedef void (*ClearFun)(void* value);
// initial_capacity is the size of the initial hash map;
// it must be a power of 2 (and thus must not be 0).
SimpleHashMap(MatchFun match, uint32_t initial_capacity);
~SimpleHashMap();
static bool SamePointerValue(void* key1, void* key2) { return key1 == key2; }
static uint32_t StringHash(const char* key) {
uint32_t hash_ = 0;
if (key == nullptr) return hash_;
int len = strlen(key);
for (int i = 0; i < len; i++) {
hash_ += key[i];
hash_ += hash_ << 10;
hash_ ^= hash_ >> 6;
}
hash_ += hash_ << 3;
hash_ ^= hash_ >> 11;
hash_ += hash_ << 15;
return hash_ == 0 ? 1 : hash_;
}
static bool SameStringValue(void* key1, void* key2) {
return strcmp(reinterpret_cast<char*>(key1),
reinterpret_cast<char*>(key2)) == 0;
}
// SimpleHashMap 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 {
Entry() : key(nullptr), value(nullptr), hash(0) {}
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 nullptr value.
// Otherwise, nullptr is returned.
Entry* Lookup(void* key, uint32_t hash, bool insert);
// Removes the entry with matching key.
//
// WARNING: This method cannot be called while iterating a `SimpleHashMap`
// otherwise the iteration might step over elements!
void Remove(void* key, uint32_t hash);
// Empties the hash map (occupancy() == 0), and calls the function 'clear' on
// each of the values if given.
void Clear(ClearFun clear = nullptr);
// The number of entries stored in the table.
intptr_t size() const { return occupancy_; }
// The capacity of the table. The implementation
// makes sure that occupancy is at most 80% of
// the table capacity.
intptr_t capacity() const { return capacity_; }
// Iteration
//
// for (Entry* p = map.Start(); p != nullptr; p = map.Next(p)) {
// ...
// }
//
// 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_;
Entry* map_end() const { return map_ + capacity_; }
Entry* Probe(void* key, uint32_t hash);
void Initialize(uint32_t capacity);
void Resize();
friend class IntSet; // From hashmap_test.cc
DISALLOW_COPY_AND_ASSIGN(SimpleHashMap);
};
} // namespace dart
#endif // RUNTIME_PLATFORM_HASHMAP_H_