runtime/Lookup.h

   1 /*
   2  *  Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
   3  *  Copyright (C) 2003, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
   4  *
   5  *  This library is free software; you can redistribute it and/or
   6  *  modify it under the terms of the GNU Lesser General Public
   7  *  License as published by the Free Software Foundation; either
   8  *  version 2 of the License, or (at your option) any later version.
   9  *
  10  *  This library is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  *  Lesser General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU Lesser General Public
  16  *  License along with this library; if not, write to the Free Software
  17  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  18  *
  19  */
  20
  21 #ifndef Lookup_h
  22 #define Lookup_h
  23
  24 #include "CallFrame.h"
  25 #include "Intrinsic.h"
  26 #include "Identifier.h"
  27 #include "JSGlobalObject.h"
  28 #include "PropertySlot.h"
  29 #include <stdio.h>
  30 #include <wtf/Assertions.h>
  31
  32 namespace JSC {
  33     // Hash table generated by the create_hash_table script.
  34     struct HashTableValue {
  35         const char* key; // property name
  36         unsigned char attributes; // JSObject attributes
  37         intptr_t value1;
  38         intptr_t value2;
  39         Intrinsic intrinsic;
  40     };
  41
  42     // FIXME: There is no reason this get function can't be simpler.
  43     // ie. typedef JSValue (*GetFunction)(ExecState*, JSObject* baseObject)
  44     typedef PropertySlot::GetValueFunc GetFunction;
  45     typedef void (*PutFunction)(ExecState*, JSObject* baseObject, JSValue value);
  46
  47     class HashEntry {
  48         WTF_MAKE_FAST_ALLOCATED;
  49     public:
  50         void initialize(StringImpl* key, unsigned char attributes, intptr_t v1, intptr_t v2, Intrinsic intrinsic)
  51         {
  52             m_key = key;
  53             m_attributes = attributes;
  54             m_u.store.value1 = v1;
  55             m_u.store.value2 = v2;
  56             m_u.function.intrinsic = intrinsic;
  57             m_next = 0;
  58         }
  59
  60         void setKey(StringImpl* key) { m_key = key; }
  61         StringImpl* key() const { return m_key; }
  62
  63         unsigned char attributes() const { return m_attributes; }
  64
  65         Intrinsic intrinsic() const
  66         {
  67             ASSERT(m_attributes & Function);
  68             return m_u.function.intrinsic;
  69         }
  70
  71         NativeFunction function() const { ASSERT(m_attributes & Function); return m_u.function.functionValue; }
  72         unsigned char functionLength() const { ASSERT(m_attributes & Function); return static_cast<unsigned char>(m_u.function.length); }
  73
  74         GetFunction propertyGetter() const { ASSERT(!(m_attributes & Function)); return m_u.property.get; }
  75         PutFunction propertyPutter() const { ASSERT(!(m_attributes & Function)); return m_u.property.put; }
  76
  77         intptr_t lexerValue() const { ASSERT(!m_attributes); return m_u.lexer.value; }
  78
  79         void setNext(HashEntry *next) { m_next = next; }
  80         HashEntry* next() const { return m_next; }
  81
  82     private:
  83         StringImpl* m_key;
  84         unsigned char m_attributes; // JSObject attributes
  85
  86         union {
  87             struct {
  88                 intptr_t value1;
  89                 intptr_t value2;
  90             } store;
  91             struct {
  92                 NativeFunction functionValue;
  93                 intptr_t length; // number of arguments for function
  94                 Intrinsic intrinsic;
  95             } function;
  96             struct {
  97                 GetFunction get;
  98                 PutFunction put;
  99             } property;
 100             struct {
 101                 intptr_t value;
 102                 intptr_t unused;
 103             } lexer;
 104         } m_u;
 105
 106         HashEntry* m_next;
 107     };
 108
 109     struct HashTable {
 110
 111         int compactSize;
 112         int compactHashSizeMask;
 113
 114         const HashTableValue* values; // Fixed values generated by script.
 115         mutable const HashEntry* table; // Table allocated at runtime.
 116
 117         ALWAYS_INLINE void initializeIfNeeded(JSGlobalData* globalData) const
 118         {
 119             if (!table)
 120                 createTable(globalData);
 121         }
 122
 123         ALWAYS_INLINE void initializeIfNeeded(ExecState* exec) const
 124         {
 125             if (!table)
 126                 createTable(&exec->globalData());
 127         }
 128
 129         JS_EXPORT_PRIVATE void deleteTable() const;
 130
 131         // Find an entry in the table, and return the entry.
 132         ALWAYS_INLINE const HashEntry* entry(JSGlobalData* globalData, const Identifier& identifier) const
 133         {
 134             initializeIfNeeded(globalData);
 135             return entry(identifier);
 136         }
 137
 138         ALWAYS_INLINE const HashEntry* entry(ExecState* exec, const Identifier& identifier) const
 139         {
 140             initializeIfNeeded(exec);
 141             return entry(identifier);
 142         }
 143
 144         class ConstIterator {
 145         public:
 146             ConstIterator(const HashTable* table, int position)
 147                 : m_table(table)
 148                 , m_position(position)
 149             {
 150                 skipInvalidKeys();
 151             }
 152
 153             const HashEntry* operator->()
 154             {
 155                 return &m_table->table[m_position];
 156             }
 157
 158             const HashEntry* operator*()
 159             {
 160                 return &m_table->table[m_position];
 161             }
 162
 163             bool operator!=(const ConstIterator& other)
 164             {
 165                 ASSERT(m_table == other.m_table);
 166                 return m_position != other.m_position;
 167             }
 168
 169             ConstIterator& operator++()
 170             {
 171                 ASSERT(m_position < m_table->compactSize);
 172                 ++m_position;
 173                 skipInvalidKeys();
 174                 return *this;
 175             }
 176
 177         private:
 178             void skipInvalidKeys()
 179             {
 180                 ASSERT(m_position <= m_table->compactSize);
 181                 while (m_position < m_table->compactSize && !m_table->table[m_position].key())
 182                     ++m_position;
 183                 ASSERT(m_position <= m_table->compactSize);
 184             }
 185
 186             const HashTable* m_table;
 187             int m_position;
 188         };
 189
 190         ConstIterator begin(JSGlobalData& globalData) const
 191         {
 192             initializeIfNeeded(&globalData);
 193             return ConstIterator(this, 0);
 194         }
 195         ConstIterator end(JSGlobalData& globalData) const
 196         {
 197             initializeIfNeeded(&globalData);
 198             return ConstIterator(this, compactSize);
 199         }
 200
 201     private:
 202         ALWAYS_INLINE const HashEntry* entry(const Identifier& identifier) const
 203         {
 204             ASSERT(table);
 205
 206             const HashEntry* entry = &table[identifier.impl()->existingHash() & compactHashSizeMask];
 207
 208             if (!entry->key())
 209                 return 0;
 210
 211             do {
 212                 if (entry->key() == identifier.impl())
 213                     return entry;
 214                 entry = entry->next();
 215             } while (entry);
 216
 217             return 0;
 218         }
 219
 220         // Convert the hash table keys to identifiers.
 221         JS_EXPORT_PRIVATE void createTable(JSGlobalData*) const;
 222     };
 223
 224     JS_EXPORT_PRIVATE bool setUpStaticFunctionSlot(ExecState*, const HashEntry*, JSObject* thisObject, const Identifier& propertyName, PropertySlot&);
 225
 226     /**
 227      * This method does it all (looking in the hashtable, checking for function
 228      * overrides, creating the function or retrieving from cache, calling
 229      * getValueProperty in case of a non-function property, forwarding to parent if
 230      * unknown property).
 231      */
 232     template <class ThisImp, class ParentImp>
 233     inline bool getStaticPropertySlot(ExecState* exec, const HashTable* table, ThisImp* thisObj, const Identifier& propertyName, PropertySlot& slot)
 234     {
 235         const HashEntry* entry = table->entry(exec, propertyName);
 236
 237         if (!entry) // not found, forward to parent
 238             return ParentImp::getOwnPropertySlot(thisObj, exec, propertyName, slot);
 239
 240         if (entry->attributes() & Function)
 241             return setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
 242
 243         slot.setCacheableCustom(thisObj, entry->propertyGetter());
 244         return true;
 245     }
 246
 247     template <class ThisImp, class ParentImp>
 248     inline bool getStaticPropertyDescriptor(ExecState* exec, const HashTable* table, ThisImp* thisObj, const Identifier& propertyName, PropertyDescriptor& descriptor)
 249     {
 250         const HashEntry* entry = table->entry(exec, propertyName);
 251
 252         if (!entry) // not found, forward to parent
 253             return ParentImp::getOwnPropertyDescriptor(thisObj, exec, propertyName, descriptor);
 254
 255         PropertySlot slot;
 256         if (entry->attributes() & Function) {
 257             bool present = setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
 258             if (present)
 259                 descriptor.setDescriptor(slot.getValue(exec, propertyName), entry->attributes());
 260             return present;
 261         }
 262
 263         slot.setCustom(thisObj, entry->propertyGetter());
 264         descriptor.setDescriptor(slot.getValue(exec, propertyName), entry->attributes());
 265         return true;
 266     }
 267
 268     /**
 269      * Simplified version of getStaticPropertySlot in case there are only functions.
 270      * Using this instead of getStaticPropertySlot allows 'this' to avoid implementing
 271      * a dummy getValueProperty.
 272      */
 273     template <class ParentImp>
 274     inline bool getStaticFunctionSlot(ExecState* exec, const HashTable* table, JSObject* thisObj, const Identifier& propertyName, PropertySlot& slot)
 275     {
 276         if (ParentImp::getOwnPropertySlot(thisObj, exec, propertyName, slot))
 277             return true;
 278
 279         const HashEntry* entry = table->entry(exec, propertyName);
 280         if (!entry)
 281             return false;
 282
 283         return setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
 284     }
 285
 286     /**
 287      * Simplified version of getStaticPropertyDescriptor in case there are only functions.
 288      * Using this instead of getStaticPropertyDescriptor allows 'this' to avoid implementing
 289      * a dummy getValueProperty.
 290      */
 291     template <class ParentImp>
 292     inline bool getStaticFunctionDescriptor(ExecState* exec, const HashTable* table, JSObject* thisObj, const Identifier& propertyName, PropertyDescriptor& descriptor)
 293     {
 294         if (ParentImp::getOwnPropertyDescriptor(static_cast<ParentImp*>(thisObj), exec, propertyName, descriptor))
 295             return true;
 296
 297         const HashEntry* entry = table->entry(exec, propertyName);
 298         if (!entry)
 299             return false;
 300
 301         PropertySlot slot;
 302         bool present = setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
 303         if (present)
 304             descriptor.setDescriptor(slot.getValue(exec, propertyName), entry->attributes());
 305         return present;
 306     }
 307
 308     /**
 309      * Simplified version of getStaticPropertySlot in case there are no functions, only "values".
 310      * Using this instead of getStaticPropertySlot removes the need for a FuncImp class.
 311      */
 312     template <class ThisImp, class ParentImp>
 313     inline bool getStaticValueSlot(ExecState* exec, const HashTable* table, ThisImp* thisObj, const Identifier& propertyName, PropertySlot& slot)
 314     {
 315         const HashEntry* entry = table->entry(exec, propertyName);
 316
 317         if (!entry) // not found, forward to parent
 318             return ParentImp::getOwnPropertySlot(thisObj, exec, propertyName, slot);
 319
 320         ASSERT(!(entry->attributes() & Function));
 321
 322         slot.setCacheableCustom(thisObj, entry->propertyGetter());
 323         return true;
 324     }
 325
 326     /**
 327      * Simplified version of getStaticPropertyDescriptor in case there are no functions, only "values".
 328      * Using this instead of getStaticPropertyDescriptor removes the need for a FuncImp class.
 329      */
 330     template <class ThisImp, class ParentImp>
 331     inline bool getStaticValueDescriptor(ExecState* exec, const HashTable* table, ThisImp* thisObj, const Identifier& propertyName, PropertyDescriptor& descriptor)
 332     {
 333         const HashEntry* entry = table->entry(exec, propertyName);
 334
 335         if (!entry) // not found, forward to parent
 336             return ParentImp::getOwnPropertyDescriptor(thisObj, exec, propertyName, descriptor);
 337
 338         ASSERT(!(entry->attributes() & Function));
 339         PropertySlot slot;
 340         slot.setCustom(thisObj, entry->propertyGetter());
 341         descriptor.setDescriptor(slot.getValue(exec, propertyName), entry->attributes());
 342         return true;
 343     }
 344
 345     /**
 346      * This one is for "put".
 347      * It looks up a hash entry for the property to be set.  If an entry
 348      * is found it sets the value and returns true, else it returns false.
 349      */
 350     template <class ThisImp>
 351     inline bool lookupPut(ExecState* exec, const Identifier& propertyName, JSValue value, const HashTable* table, ThisImp* thisObj, bool shouldThrow = false)
 352     {
 353         const HashEntry* entry = table->entry(exec, propertyName);
 354
 355         if (!entry)
 356             return false;
 357
 358         // If this is a function put it as an override property.
 359         if (entry->attributes() & Function)
 360             thisObj->putDirect(exec->globalData(), propertyName, value);
 361         else if (!(entry->attributes() & ReadOnly))
 362             entry->propertyPutter()(exec, thisObj, value);
 363         else if (shouldThrow)
 364             throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
 365
 366         return true;
 367     }
 368
 369     /**
 370      * This one is for "put".
 371      * It calls lookupPut<ThisImp>() to set the value.  If that call
 372      * returns false (meaning no entry in the hash table was found),
 373      * then it calls put() on the ParentImp class.
 374      */
 375     template <class ThisImp, class ParentImp>
 376     inline void lookupPut(ExecState* exec, const Identifier& propertyName, JSValue value, const HashTable* table, ThisImp* thisObj, PutPropertySlot& slot)
 377     {
 378         if (!lookupPut<ThisImp>(exec, propertyName, value, table, thisObj, slot.isStrictMode()))
 379             ParentImp::put(thisObj, exec, propertyName, value, slot); // not found: forward to parent
 380     }
 381
 382 } // namespace JSC
 383
 384 #endif // Lookup_h