Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 1 | // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef V8_UTIL_H_ |
| 6 | #define V8_UTIL_H_ |
| 7 | |
| 8 | #include "v8.h" |
| 9 | #include <map> |
| 10 | #include <vector> |
| 11 | |
| 12 | /** |
| 13 | * Support for Persistent containers. |
| 14 | * |
| 15 | * C++11 embedders can use STL containers with UniquePersistent values, |
| 16 | * but pre-C++11 does not support the required move semantic and hence |
| 17 | * may want these container classes. |
| 18 | */ |
| 19 | namespace v8 { |
| 20 | |
| 21 | typedef uintptr_t PersistentContainerValue; |
| 22 | static const uintptr_t kPersistentContainerNotFound = 0; |
| 23 | enum PersistentContainerCallbackType { |
| 24 | kNotWeak, |
| 25 | kWeak |
| 26 | }; |
| 27 | |
| 28 | |
| 29 | /** |
| 30 | * A default trait implemenation for PersistentValueMap which uses std::map |
| 31 | * as a backing map. |
| 32 | * |
| 33 | * Users will have to implement their own weak callbacks & dispose traits. |
| 34 | */ |
| 35 | template<typename K, typename V> |
| 36 | class StdMapTraits { |
| 37 | public: |
| 38 | // STL map & related: |
| 39 | typedef std::map<K, PersistentContainerValue> Impl; |
| 40 | typedef typename Impl::iterator Iterator; |
| 41 | |
| 42 | static bool Empty(Impl* impl) { return impl->empty(); } |
| 43 | static size_t Size(Impl* impl) { return impl->size(); } |
| 44 | static void Swap(Impl& a, Impl& b) { std::swap(a, b); } // NOLINT |
| 45 | static Iterator Begin(Impl* impl) { return impl->begin(); } |
| 46 | static Iterator End(Impl* impl) { return impl->end(); } |
| 47 | static K Key(Iterator it) { return it->first; } |
| 48 | static PersistentContainerValue Value(Iterator it) { return it->second; } |
| 49 | static PersistentContainerValue Set(Impl* impl, K key, |
| 50 | PersistentContainerValue value) { |
| 51 | std::pair<Iterator, bool> res = impl->insert(std::make_pair(key, value)); |
| 52 | PersistentContainerValue old_value = kPersistentContainerNotFound; |
| 53 | if (!res.second) { |
| 54 | old_value = res.first->second; |
| 55 | res.first->second = value; |
| 56 | } |
| 57 | return old_value; |
| 58 | } |
| 59 | static PersistentContainerValue Get(Impl* impl, K key) { |
| 60 | Iterator it = impl->find(key); |
| 61 | if (it == impl->end()) return kPersistentContainerNotFound; |
| 62 | return it->second; |
| 63 | } |
| 64 | static PersistentContainerValue Remove(Impl* impl, K key) { |
| 65 | Iterator it = impl->find(key); |
| 66 | if (it == impl->end()) return kPersistentContainerNotFound; |
| 67 | PersistentContainerValue value = it->second; |
| 68 | impl->erase(it); |
| 69 | return value; |
| 70 | } |
| 71 | }; |
| 72 | |
| 73 | |
| 74 | /** |
| 75 | * A default trait implementation for PersistentValueMap, which inherits |
| 76 | * a std:map backing map from StdMapTraits and holds non-weak persistent |
| 77 | * objects and has no special Dispose handling. |
| 78 | * |
| 79 | * You should not derive from this class, since MapType depends on the |
| 80 | * surrounding class, and hence a subclass cannot simply inherit the methods. |
| 81 | */ |
| 82 | template<typename K, typename V> |
| 83 | class DefaultPersistentValueMapTraits : public StdMapTraits<K, V> { |
| 84 | public: |
| 85 | // Weak callback & friends: |
| 86 | static const PersistentContainerCallbackType kCallbackType = kNotWeak; |
| 87 | typedef PersistentValueMap<K, V, DefaultPersistentValueMapTraits<K, V> > |
| 88 | MapType; |
| 89 | typedef void WeakCallbackDataType; |
| 90 | |
| 91 | static WeakCallbackDataType* WeakCallbackParameter( |
| 92 | MapType* map, const K& key, Local<V> value) { |
| 93 | return NULL; |
| 94 | } |
| 95 | static MapType* MapFromWeakCallbackData( |
| 96 | const WeakCallbackData<V, WeakCallbackDataType>& data) { |
| 97 | return NULL; |
| 98 | } |
| 99 | static K KeyFromWeakCallbackData( |
| 100 | const WeakCallbackData<V, WeakCallbackDataType>& data) { |
| 101 | return K(); |
| 102 | } |
| 103 | static void DisposeCallbackData(WeakCallbackDataType* data) { } |
| 104 | static void Dispose(Isolate* isolate, UniquePersistent<V> value, K key) { } |
| 105 | }; |
| 106 | |
| 107 | |
| 108 | /** |
| 109 | * A map wrapper that allows using UniquePersistent as a mapped value. |
| 110 | * C++11 embedders don't need this class, as they can use UniquePersistent |
| 111 | * directly in std containers. |
| 112 | * |
| 113 | * The map relies on a backing map, whose type and accessors are described |
| 114 | * by the Traits class. The backing map will handle values of type |
| 115 | * PersistentContainerValue, with all conversion into and out of V8 |
| 116 | * handles being transparently handled by this class. |
| 117 | */ |
| 118 | template<typename K, typename V, typename Traits> |
| 119 | class PersistentValueMap { |
| 120 | public: |
| 121 | explicit PersistentValueMap(Isolate* isolate) : isolate_(isolate) {} |
| 122 | |
| 123 | ~PersistentValueMap() { Clear(); } |
| 124 | |
| 125 | Isolate* GetIsolate() { return isolate_; } |
| 126 | |
| 127 | /** |
| 128 | * Return size of the map. |
| 129 | */ |
| 130 | size_t Size() { return Traits::Size(&impl_); } |
| 131 | |
| 132 | /** |
| 133 | * Return whether the map holds weak persistents. |
| 134 | */ |
| 135 | bool IsWeak() { return Traits::kCallbackType != kNotWeak; } |
| 136 | |
| 137 | /** |
| 138 | * Get value stored in map. |
| 139 | */ |
| 140 | Local<V> Get(const K& key) { |
| 141 | return Local<V>::New(isolate_, FromVal(Traits::Get(&impl_, key))); |
| 142 | } |
| 143 | |
| 144 | /** |
| 145 | * Check whether a value is contained in the map. |
| 146 | */ |
| 147 | bool Contains(const K& key) { |
| 148 | return Traits::Get(&impl_, key) != kPersistentContainerNotFound; |
| 149 | } |
| 150 | |
| 151 | /** |
| 152 | * Get value stored in map and set it in returnValue. |
| 153 | * Return true if a value was found. |
| 154 | */ |
| 155 | bool SetReturnValue(const K& key, |
| 156 | ReturnValue<Value> returnValue) { |
| 157 | return SetReturnValueFromVal(&returnValue, Traits::Get(&impl_, key)); |
| 158 | } |
| 159 | |
| 160 | /** |
| 161 | * Call Isolate::SetReference with the given parent and the map value. |
| 162 | */ |
| 163 | void SetReference(const K& key, |
| 164 | const Persistent<Object>& parent) { |
| 165 | GetIsolate()->SetReference( |
| 166 | reinterpret_cast<internal::Object**>(parent.val_), |
| 167 | reinterpret_cast<internal::Object**>(FromVal(Traits::Get(&impl_, key)))); |
| 168 | } |
| 169 | |
| 170 | /** |
| 171 | * Put value into map. Depending on Traits::kIsWeak, the value will be held |
| 172 | * by the map strongly or weakly. |
| 173 | * Returns old value as UniquePersistent. |
| 174 | */ |
| 175 | UniquePersistent<V> Set(const K& key, Local<V> value) { |
| 176 | UniquePersistent<V> persistent(isolate_, value); |
| 177 | return SetUnique(key, &persistent); |
| 178 | } |
| 179 | |
| 180 | /** |
| 181 | * Put value into map, like Set(const K&, Local<V>). |
| 182 | */ |
| 183 | UniquePersistent<V> Set(const K& key, UniquePersistent<V> value) { |
| 184 | return SetUnique(key, &value); |
| 185 | } |
| 186 | |
| 187 | /** |
| 188 | * Return value for key and remove it from the map. |
| 189 | */ |
| 190 | UniquePersistent<V> Remove(const K& key) { |
| 191 | return Release(Traits::Remove(&impl_, key)).Pass(); |
| 192 | } |
| 193 | |
| 194 | /** |
| 195 | * Traverses the map repeatedly, |
| 196 | * in case side effects of disposal cause insertions. |
| 197 | **/ |
| 198 | void Clear() { |
| 199 | typedef typename Traits::Iterator It; |
| 200 | HandleScope handle_scope(isolate_); |
| 201 | // TODO(dcarney): figure out if this swap and loop is necessary. |
| 202 | while (!Traits::Empty(&impl_)) { |
| 203 | typename Traits::Impl impl; |
| 204 | Traits::Swap(impl_, impl); |
| 205 | for (It i = Traits::Begin(&impl); i != Traits::End(&impl); ++i) { |
| 206 | Traits::Dispose(isolate_, Release(Traits::Value(i)).Pass(), |
| 207 | Traits::Key(i)); |
| 208 | } |
| 209 | } |
| 210 | } |
| 211 | |
| 212 | /** |
| 213 | * Helper class for GetReference/SetWithReference. Do not use outside |
| 214 | * that context. |
| 215 | */ |
| 216 | class PersistentValueReference { |
| 217 | public: |
| 218 | PersistentValueReference() : value_(kPersistentContainerNotFound) { } |
| 219 | PersistentValueReference(const PersistentValueReference& other) |
| 220 | : value_(other.value_) { } |
| 221 | |
| 222 | Local<V> NewLocal(Isolate* isolate) const { |
| 223 | return Local<V>::New(isolate, FromVal(value_)); |
| 224 | } |
| 225 | bool IsEmpty() const { |
| 226 | return value_ == kPersistentContainerNotFound; |
| 227 | } |
| 228 | template<typename T> |
| 229 | bool SetReturnValue(ReturnValue<T> returnValue) { |
| 230 | return SetReturnValueFromVal(&returnValue, value_); |
| 231 | } |
| 232 | void Reset() { |
| 233 | value_ = kPersistentContainerNotFound; |
| 234 | } |
| 235 | void operator=(const PersistentValueReference& other) { |
| 236 | value_ = other.value_; |
| 237 | } |
| 238 | |
| 239 | private: |
| 240 | friend class PersistentValueMap; |
| 241 | |
| 242 | explicit PersistentValueReference(PersistentContainerValue value) |
| 243 | : value_(value) { } |
| 244 | |
| 245 | void operator=(PersistentContainerValue value) { |
| 246 | value_ = value; |
| 247 | } |
| 248 | |
| 249 | PersistentContainerValue value_; |
| 250 | }; |
| 251 | |
| 252 | /** |
| 253 | * Get a reference to a map value. This enables fast, repeated access |
| 254 | * to a value stored in the map while the map remains unchanged. |
| 255 | * |
| 256 | * Careful: This is potentially unsafe, so please use with care. |
| 257 | * The value will become invalid if the value for this key changes |
| 258 | * in the underlying map, as a result of Set or Remove for the same |
| 259 | * key; as a result of the weak callback for the same key; or as a |
| 260 | * result of calling Clear() or destruction of the map. |
| 261 | */ |
| 262 | PersistentValueReference GetReference(const K& key) { |
| 263 | return PersistentValueReference(Traits::Get(&impl_, key)); |
| 264 | } |
| 265 | |
| 266 | /** |
| 267 | * Put a value into the map and update the reference. |
| 268 | * Restrictions of GetReference apply here as well. |
| 269 | */ |
| 270 | UniquePersistent<V> Set(const K& key, UniquePersistent<V> value, |
| 271 | PersistentValueReference* reference) { |
| 272 | *reference = Leak(&value); |
| 273 | return SetUnique(key, &value); |
| 274 | } |
| 275 | |
| 276 | private: |
| 277 | PersistentValueMap(PersistentValueMap&); |
| 278 | void operator=(PersistentValueMap&); |
| 279 | |
| 280 | /** |
| 281 | * Put the value into the map, and set the 'weak' callback when demanded |
| 282 | * by the Traits class. |
| 283 | */ |
| 284 | UniquePersistent<V> SetUnique(const K& key, UniquePersistent<V>* persistent) { |
| 285 | if (Traits::kCallbackType != kNotWeak) { |
| 286 | Local<V> value(Local<V>::New(isolate_, *persistent)); |
| 287 | persistent->template SetWeak<typename Traits::WeakCallbackDataType>( |
| 288 | Traits::WeakCallbackParameter(this, key, value), WeakCallback); |
| 289 | } |
| 290 | PersistentContainerValue old_value = |
| 291 | Traits::Set(&impl_, key, ClearAndLeak(persistent)); |
| 292 | return Release(old_value).Pass(); |
| 293 | } |
| 294 | |
| 295 | static void WeakCallback( |
| 296 | const WeakCallbackData<V, typename Traits::WeakCallbackDataType>& data) { |
| 297 | if (Traits::kCallbackType != kNotWeak) { |
| 298 | PersistentValueMap<K, V, Traits>* persistentValueMap = |
| 299 | Traits::MapFromWeakCallbackData(data); |
| 300 | K key = Traits::KeyFromWeakCallbackData(data); |
| 301 | Traits::Dispose(data.GetIsolate(), |
| 302 | persistentValueMap->Remove(key).Pass(), key); |
| 303 | Traits::DisposeCallbackData(data.GetParameter()); |
| 304 | } |
| 305 | } |
| 306 | |
| 307 | static V* FromVal(PersistentContainerValue v) { |
| 308 | return reinterpret_cast<V*>(v); |
| 309 | } |
| 310 | |
| 311 | static bool SetReturnValueFromVal( |
| 312 | ReturnValue<Value>* returnValue, PersistentContainerValue value) { |
| 313 | bool hasValue = value != kPersistentContainerNotFound; |
| 314 | if (hasValue) { |
| 315 | returnValue->SetInternal( |
| 316 | *reinterpret_cast<internal::Object**>(FromVal(value))); |
| 317 | } |
| 318 | return hasValue; |
| 319 | } |
| 320 | |
| 321 | static PersistentContainerValue ClearAndLeak( |
| 322 | UniquePersistent<V>* persistent) { |
| 323 | V* v = persistent->val_; |
| 324 | persistent->val_ = 0; |
| 325 | return reinterpret_cast<PersistentContainerValue>(v); |
| 326 | } |
| 327 | |
| 328 | static PersistentContainerValue Leak( |
| 329 | UniquePersistent<V>* persistent) { |
| 330 | return reinterpret_cast<PersistentContainerValue>(persistent->val_); |
| 331 | } |
| 332 | |
| 333 | /** |
| 334 | * Return a container value as UniquePersistent and make sure the weak |
| 335 | * callback is properly disposed of. All remove functionality should go |
| 336 | * through this. |
| 337 | */ |
| 338 | static UniquePersistent<V> Release(PersistentContainerValue v) { |
| 339 | UniquePersistent<V> p; |
| 340 | p.val_ = FromVal(v); |
| 341 | if (Traits::kCallbackType != kNotWeak && p.IsWeak()) { |
| 342 | Traits::DisposeCallbackData( |
| 343 | p.template ClearWeak<typename Traits::WeakCallbackDataType>()); |
| 344 | } |
| 345 | return p.Pass(); |
| 346 | } |
| 347 | |
| 348 | Isolate* isolate_; |
| 349 | typename Traits::Impl impl_; |
| 350 | }; |
| 351 | |
| 352 | |
| 353 | /** |
| 354 | * A map that uses UniquePersistent as value and std::map as the backing |
| 355 | * implementation. Persistents are held non-weak. |
| 356 | * |
| 357 | * C++11 embedders don't need this class, as they can use |
| 358 | * UniquePersistent directly in std containers. |
| 359 | */ |
| 360 | template<typename K, typename V, |
| 361 | typename Traits = DefaultPersistentValueMapTraits<K, V> > |
| 362 | class StdPersistentValueMap : public PersistentValueMap<K, V, Traits> { |
| 363 | public: |
| 364 | explicit StdPersistentValueMap(Isolate* isolate) |
| 365 | : PersistentValueMap<K, V, Traits>(isolate) {} |
| 366 | }; |
| 367 | |
| 368 | |
| 369 | class DefaultPersistentValueVectorTraits { |
| 370 | public: |
| 371 | typedef std::vector<PersistentContainerValue> Impl; |
| 372 | |
| 373 | static void Append(Impl* impl, PersistentContainerValue value) { |
| 374 | impl->push_back(value); |
| 375 | } |
| 376 | static bool IsEmpty(const Impl* impl) { |
| 377 | return impl->empty(); |
| 378 | } |
| 379 | static size_t Size(const Impl* impl) { |
| 380 | return impl->size(); |
| 381 | } |
| 382 | static PersistentContainerValue Get(const Impl* impl, size_t i) { |
| 383 | return (i < impl->size()) ? impl->at(i) : kPersistentContainerNotFound; |
| 384 | } |
| 385 | static void ReserveCapacity(Impl* impl, size_t capacity) { |
| 386 | impl->reserve(capacity); |
| 387 | } |
| 388 | static void Clear(Impl* impl) { |
| 389 | impl->clear(); |
| 390 | } |
| 391 | }; |
| 392 | |
| 393 | |
| 394 | /** |
| 395 | * A vector wrapper that safely stores UniquePersistent values. |
| 396 | * C++11 embedders don't need this class, as they can use UniquePersistent |
| 397 | * directly in std containers. |
| 398 | * |
| 399 | * This class relies on a backing vector implementation, whose type and methods |
| 400 | * are described by the Traits class. The backing map will handle values of type |
| 401 | * PersistentContainerValue, with all conversion into and out of V8 |
| 402 | * handles being transparently handled by this class. |
| 403 | */ |
| 404 | template<typename V, typename Traits = DefaultPersistentValueVectorTraits> |
| 405 | class PersistentValueVector { |
| 406 | public: |
| 407 | explicit PersistentValueVector(Isolate* isolate) : isolate_(isolate) { } |
| 408 | |
| 409 | ~PersistentValueVector() { |
| 410 | Clear(); |
| 411 | } |
| 412 | |
| 413 | /** |
| 414 | * Append a value to the vector. |
| 415 | */ |
| 416 | void Append(Local<V> value) { |
| 417 | UniquePersistent<V> persistent(isolate_, value); |
| 418 | Traits::Append(&impl_, ClearAndLeak(&persistent)); |
| 419 | } |
| 420 | |
| 421 | /** |
| 422 | * Append a persistent's value to the vector. |
| 423 | */ |
| 424 | void Append(UniquePersistent<V> persistent) { |
| 425 | Traits::Append(&impl_, ClearAndLeak(&persistent)); |
| 426 | } |
| 427 | |
| 428 | /** |
| 429 | * Are there any values in the vector? |
| 430 | */ |
| 431 | bool IsEmpty() const { |
| 432 | return Traits::IsEmpty(&impl_); |
| 433 | } |
| 434 | |
| 435 | /** |
| 436 | * How many elements are in the vector? |
| 437 | */ |
| 438 | size_t Size() const { |
| 439 | return Traits::Size(&impl_); |
| 440 | } |
| 441 | |
| 442 | /** |
| 443 | * Retrieve the i-th value in the vector. |
| 444 | */ |
| 445 | Local<V> Get(size_t index) const { |
| 446 | return Local<V>::New(isolate_, FromVal(Traits::Get(&impl_, index))); |
| 447 | } |
| 448 | |
| 449 | /** |
| 450 | * Remove all elements from the vector. |
| 451 | */ |
| 452 | void Clear() { |
| 453 | size_t length = Traits::Size(&impl_); |
| 454 | for (size_t i = 0; i < length; i++) { |
| 455 | UniquePersistent<V> p; |
| 456 | p.val_ = FromVal(Traits::Get(&impl_, i)); |
| 457 | } |
| 458 | Traits::Clear(&impl_); |
| 459 | } |
| 460 | |
| 461 | /** |
| 462 | * Reserve capacity in the vector. |
| 463 | * (Efficiency gains depend on the backing implementation.) |
| 464 | */ |
| 465 | void ReserveCapacity(size_t capacity) { |
| 466 | Traits::ReserveCapacity(&impl_, capacity); |
| 467 | } |
| 468 | |
| 469 | private: |
| 470 | static PersistentContainerValue ClearAndLeak( |
| 471 | UniquePersistent<V>* persistent) { |
| 472 | V* v = persistent->val_; |
| 473 | persistent->val_ = 0; |
| 474 | return reinterpret_cast<PersistentContainerValue>(v); |
| 475 | } |
| 476 | |
| 477 | static V* FromVal(PersistentContainerValue v) { |
| 478 | return reinterpret_cast<V*>(v); |
| 479 | } |
| 480 | |
| 481 | Isolate* isolate_; |
| 482 | typename Traits::Impl impl_; |
| 483 | }; |
| 484 | |
| 485 | } // namespace v8 |
| 486 | |
| 487 | #endif // V8_UTIL_H_ |