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 "Identifier.h"
  26 #include "JSGlobalObject.h"
  27 #include "JSObject.h"
  28 #include "PropertySlot.h"
  29 #include <stdio.h>
  30 #include <wtf/Assertions.h>
  31
  32 // Bug #26843: Work around Metrowerks compiler bug
  33 #if COMPILER(WINSCW)
  34 #define JSC_CONST_HASHTABLE
  35 #else
  36 #define JSC_CONST_HASHTABLE const
  37 #endif
  38
  39 namespace JSC {
  40     // Hash table generated by the create_hash_table script.
  41     struct HashTableValue {
  42         const char* key; // property name
  43         unsigned char attributes; // JSObject attributes
  44         intptr_t value1;
  45         intptr_t value2;
  46 #if ENABLE(JIT)
  47         ThunkGenerator generator;
  48 #endif
  49     };
  50
  51     // FIXME: There is no reason this get function can't be simpler.
  52     // ie. typedef JSValue (*GetFunction)(ExecState*, JSObject* baseObject)
  53     typedef PropertySlot::GetValueFunc GetFunction;
  54     typedef void (*PutFunction)(ExecState*, JSObject* baseObject, JSValue value);
  55
  56     class HashEntry : public FastAllocBase {
  57     public:
  58         void initialize(UString::Rep* key, unsigned char attributes, intptr_t v1, intptr_t v2
  59 #if ENABLE(JIT)
  60                         , ThunkGenerator generator = 0
  61 #endif
  62                         )
  63         {
  64             m_key = key;
  65             m_attributes = attributes;
  66             m_u.store.value1 = v1;
  67             m_u.store.value2 = v2;
  68 #if ENABLE(JIT)
  69             m_u.function.generator = generator;
  70 #endif
  71             m_next = 0;
  72         }
  73
  74         void setKey(UString::Rep* key) { m_key = key; }
  75         UString::Rep* key() const { return m_key; }
  76
  77         unsigned char attributes() const { return m_attributes; }
  78
  79 #if ENABLE(JIT)
  80         ThunkGenerator generator() const { ASSERT(m_attributes & Function); return m_u.function.generator; }
  81 #endif
  82         NativeFunction function() const { ASSERT(m_attributes & Function); return m_u.function.functionValue; }
  83         unsigned char functionLength() const { ASSERT(m_attributes & Function); return static_cast<unsigned char>(m_u.function.length); }
  84
  85         GetFunction propertyGetter() const { ASSERT(!(m_attributes & Function)); return m_u.property.get; }
  86         PutFunction propertyPutter() const { ASSERT(!(m_attributes & Function)); return m_u.property.put; }
  87
  88         intptr_t lexerValue() const { ASSERT(!m_attributes); return m_u.lexer.value; }
  89
  90         void setNext(HashEntry *next) { m_next = next; }
  91         HashEntry* next() const { return m_next; }
  92
  93     private:
  94         UString::Rep* m_key;
  95         unsigned char m_attributes; // JSObject attributes
  96
  97         union {
  98             struct {
  99                 intptr_t value1;
 100                 intptr_t value2;
 101             } store;
 102             struct {
 103                 NativeFunction functionValue;
 104                 intptr_t length; // number of arguments for function
 105 #if ENABLE(JIT)
 106                 ThunkGenerator generator;
 107 #endif
 108             } function;
 109             struct {
 110                 GetFunction get;
 111                 PutFunction put;
 112             } property;
 113             struct {
 114                 intptr_t value;
 115                 intptr_t unused;
 116             } lexer;
 117         } m_u;
 118
 119         HashEntry* m_next;
 120     };
 121
 122     struct HashTable {
 123
 124         int compactSize;
 125         int compactHashSizeMask;
 126
 127         const HashTableValue* values; // Fixed values generated by script.
 128         mutable const HashEntry* table; // Table allocated at runtime.
 129
 130         ALWAYS_INLINE void initializeIfNeeded(JSGlobalData* globalData) const
 131         {
 132             if (!table)
 133                 createTable(globalData);
 134         }
 135
 136         ALWAYS_INLINE void initializeIfNeeded(ExecState* exec) const
 137         {
 138             if (!table)
 139                 createTable(&exec->globalData());
 140         }
 141
 142         void deleteTable() const;
 143
 144         // Find an entry in the table, and return the entry.
 145         ALWAYS_INLINE const HashEntry* entry(JSGlobalData* globalData, const Identifier& identifier) const
 146         {
 147             initializeIfNeeded(globalData);
 148             return entry(identifier);
 149         }
 150
 151         ALWAYS_INLINE const HashEntry* entry(ExecState* exec, const Identifier& identifier) const
 152         {
 153             initializeIfNeeded(exec);
 154             return entry(identifier);
 155         }
 156
 157     private:
 158         ALWAYS_INLINE const HashEntry* entry(const Identifier& identifier) const
 159         {
 160             ASSERT(table);
 161
 162             const HashEntry* entry = &table[identifier.ustring().rep()->existingHash() & compactHashSizeMask];
 163
 164             if (!entry->key())
 165                 return 0;
 166
 167             do {
 168                 if (entry->key() == identifier.ustring().rep())
 169                     return entry;
 170                 entry = entry->next();
 171             } while (entry);
 172
 173             return 0;
 174         }
 175
 176         // Convert the hash table keys to identifiers.
 177         void createTable(JSGlobalData*) const;
 178     };
 179
 180     void setUpStaticFunctionSlot(ExecState*, const HashEntry*, JSObject* thisObject, const Identifier& propertyName, PropertySlot&);
 181
 182     /**
 183      * This method does it all (looking in the hashtable, checking for function
 184      * overrides, creating the function or retrieving from cache, calling
 185      * getValueProperty in case of a non-function property, forwarding to parent if
 186      * unknown property).
 187      */
 188     template <class ThisImp, class ParentImp>
 189     inline bool getStaticPropertySlot(ExecState* exec, const HashTable* table, ThisImp* thisObj, const Identifier& propertyName, PropertySlot& slot)
 190     {
 191         const HashEntry* entry = table->entry(exec, propertyName);
 192
 193         if (!entry) // not found, forward to parent
 194             return thisObj->ParentImp::getOwnPropertySlot(exec, propertyName, slot);
 195
 196         if (entry->attributes() & Function)
 197             setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
 198         else
 199             slot.setCacheableCustom(thisObj, entry->propertyGetter());
 200
 201         return true;
 202     }
 203
 204     template <class ThisImp, class ParentImp>
 205     inline bool getStaticPropertyDescriptor(ExecState* exec, const HashTable* table, ThisImp* thisObj, const Identifier& propertyName, PropertyDescriptor& descriptor)
 206     {
 207         const HashEntry* entry = table->entry(exec, propertyName);
 208
 209         if (!entry) // not found, forward to parent
 210             return thisObj->ParentImp::getOwnPropertyDescriptor(exec, propertyName, descriptor);
 211
 212         PropertySlot slot;
 213         if (entry->attributes() & Function)
 214             setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
 215         else
 216             slot.setCustom(thisObj, entry->propertyGetter());
 217
 218         descriptor.setDescriptor(slot.getValue(exec, propertyName), entry->attributes());
 219         return true;
 220     }
 221
 222     /**
 223      * Simplified version of getStaticPropertySlot in case there are only functions.
 224      * Using this instead of getStaticPropertySlot allows 'this' to avoid implementing
 225      * a dummy getValueProperty.
 226      */
 227     template <class ParentImp>
 228     inline bool getStaticFunctionSlot(ExecState* exec, const HashTable* table, JSObject* thisObj, const Identifier& propertyName, PropertySlot& slot)
 229     {
 230         if (static_cast<ParentImp*>(thisObj)->ParentImp::getOwnPropertySlot(exec, propertyName, slot))
 231             return true;
 232
 233         const HashEntry* entry = table->entry(exec, propertyName);
 234         if (!entry)
 235             return false;
 236
 237         setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
 238         return true;
 239     }
 240
 241     /**
 242      * Simplified version of getStaticPropertyDescriptor in case there are only functions.
 243      * Using this instead of getStaticPropertyDescriptor allows 'this' to avoid implementing
 244      * a dummy getValueProperty.
 245      */
 246     template <class ParentImp>
 247     inline bool getStaticFunctionDescriptor(ExecState* exec, const HashTable* table, JSObject* thisObj, const Identifier& propertyName, PropertyDescriptor& descriptor)
 248     {
 249         if (static_cast<ParentImp*>(thisObj)->ParentImp::getOwnPropertyDescriptor(exec, propertyName, descriptor))
 250             return true;
 251
 252         const HashEntry* entry = table->entry(exec, propertyName);
 253         if (!entry)
 254             return false;
 255
 256         PropertySlot slot;
 257         setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
 258         descriptor.setDescriptor(slot.getValue(exec, propertyName), entry->attributes());
 259         return true;
 260     }
 261
 262     /**
 263      * Simplified version of getStaticPropertySlot in case there are no functions, only "values".
 264      * Using this instead of getStaticPropertySlot removes the need for a FuncImp class.
 265      */
 266     template <class ThisImp, class ParentImp>
 267     inline bool getStaticValueSlot(ExecState* exec, const HashTable* table, ThisImp* thisObj, const Identifier& propertyName, PropertySlot& slot)
 268     {
 269         const HashEntry* entry = table->entry(exec, propertyName);
 270
 271         if (!entry) // not found, forward to parent
 272             return thisObj->ParentImp::getOwnPropertySlot(exec, propertyName, slot);
 273
 274         ASSERT(!(entry->attributes() & Function));
 275
 276         slot.setCacheableCustom(thisObj, entry->propertyGetter());
 277         return true;
 278     }
 279
 280     /**
 281      * Simplified version of getStaticPropertyDescriptor in case there are no functions, only "values".
 282      * Using this instead of getStaticPropertyDescriptor removes the need for a FuncImp class.
 283      */
 284     template <class ThisImp, class ParentImp>
 285     inline bool getStaticValueDescriptor(ExecState* exec, const HashTable* table, ThisImp* thisObj, const Identifier& propertyName, PropertyDescriptor& descriptor)
 286     {
 287         const HashEntry* entry = table->entry(exec, propertyName);
 288
 289         if (!entry) // not found, forward to parent
 290             return thisObj->ParentImp::getOwnPropertyDescriptor(exec, propertyName, descriptor);
 291
 292         ASSERT(!(entry->attributes() & Function));
 293         PropertySlot slot;
 294         slot.setCustom(thisObj, entry->propertyGetter());
 295         descriptor.setDescriptor(slot.getValue(exec, propertyName), entry->attributes());
 296         return true;
 297     }
 298
 299     /**
 300      * This one is for "put".
 301      * It looks up a hash entry for the property to be set.  If an entry
 302      * is found it sets the value and returns true, else it returns false.
 303      */
 304     template <class ThisImp>
 305     inline bool lookupPut(ExecState* exec, const Identifier& propertyName, JSValue value, const HashTable* table, ThisImp* thisObj)
 306     {
 307         const HashEntry* entry = table->entry(exec, propertyName);
 308
 309         if (!entry)
 310             return false;
 311
 312         if (entry->attributes() & Function) { // function: put as override property
 313             if (LIKELY(value.isCell()))
 314                 thisObj->putDirectFunction(propertyName, value.asCell());
 315             else
 316                 thisObj->putDirect(propertyName, value);
 317         } else if (!(entry->attributes() & ReadOnly))
 318             entry->propertyPutter()(exec, thisObj, value);
 319
 320         return true;
 321     }
 322
 323     /**
 324      * This one is for "put".
 325      * It calls lookupPut<ThisImp>() to set the value.  If that call
 326      * returns false (meaning no entry in the hash table was found),
 327      * then it calls put() on the ParentImp class.
 328      */
 329     template <class ThisImp, class ParentImp>
 330     inline void lookupPut(ExecState* exec, const Identifier& propertyName, JSValue value, const HashTable* table, ThisImp* thisObj, PutPropertySlot& slot)
 331     {
 332         if (!lookupPut<ThisImp>(exec, propertyName, value, table, thisObj))
 333             thisObj->ParentImp::put(exec, propertyName, value, slot); // not found: forward to parent
 334     }
 335
 336 } // namespace JSC
 337
 338 #endif // Lookup_h