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
  41     // Hash table generated by the create_hash_table script.
  42     struct HashTableValue {
  43         const char* key; // property name
  44         unsigned char attributes; // JSObject attributes
  45         intptr_t value1;
  46         intptr_t value2;
  47     };
  48
  49     // FIXME: There is no reason this get function can't be simpler.
  50     // ie. typedef JSValue (*GetFunction)(ExecState*, JSObject* baseObject)
  51     typedef PropertySlot::GetValueFunc GetFunction;
  52     typedef void (*PutFunction)(ExecState*, JSObject* baseObject, JSValue value);
  53
  54     class HashEntry {
  55     public:
  56         void initialize(UString::Rep* key, unsigned char attributes, intptr_t v1, intptr_t v2)
  57         {
  58             m_key = key;
  59             m_attributes = attributes;
  60             m_u.store.value1 = v1;
  61             m_u.store.value2 = v2;
  62             m_next = 0;
  63         }
  64
  65         void setKey(UString::Rep* key) { m_key = key; }
  66         UString::Rep* key() const { return m_key; }
  67
  68         unsigned char attributes() const { return m_attributes; }
  69
  70         NativeFunction function() const { ASSERT(m_attributes & Function); return m_u.function.functionValue; }
  71         unsigned char functionLength() const { ASSERT(m_attributes & Function); return static_cast<unsigned char>(m_u.function.length); }
  72
  73         GetFunction propertyGetter() const { ASSERT(!(m_attributes & Function)); return m_u.property.get; }
  74         PutFunction propertyPutter() const { ASSERT(!(m_attributes & Function)); return m_u.property.put; }
  75
  76         intptr_t lexerValue() const { ASSERT(!m_attributes); return m_u.lexer.value; }
  77
  78         void setNext(HashEntry *next) { m_next = next; }
  79         HashEntry* next() const { return m_next; }
  80
  81     private:
  82         UString::Rep* m_key;
  83         unsigned char m_attributes; // JSObject attributes
  84
  85         union {
  86             struct {
  87                 intptr_t value1;
  88                 intptr_t value2;
  89             } store;
  90             struct {
  91                 NativeFunction functionValue;
  92                 intptr_t length; // number of arguments for function
  93             } function;
  94             struct {
  95                 GetFunction get;
  96                 PutFunction put;
  97             } property;
  98             struct {
  99                 intptr_t value;
 100                 intptr_t unused;
 101             } lexer;
 102         } m_u;
 103
 104         HashEntry* m_next;
 105     };
 106
 107     struct HashTable {
 108
 109         int compactSize;
 110         int compactHashSizeMask;
 111
 112         const HashTableValue* values; // Fixed values generated by script.
 113         mutable const HashEntry* table; // Table allocated at runtime.
 114
 115         ALWAYS_INLINE void initializeIfNeeded(JSGlobalData* globalData) const
 116         {
 117             if (!table)
 118                 createTable(globalData);
 119         }
 120
 121         ALWAYS_INLINE void initializeIfNeeded(ExecState* exec) const
 122         {
 123             if (!table)
 124                 createTable(&exec->globalData());
 125         }
 126
 127         void deleteTable() const;
 128
 129         // Find an entry in the table, and return the entry.
 130         ALWAYS_INLINE const HashEntry* entry(JSGlobalData* globalData, const Identifier& identifier) const
 131         {
 132             initializeIfNeeded(globalData);
 133             return entry(identifier);
 134         }
 135
 136         ALWAYS_INLINE const HashEntry* entry(ExecState* exec, const Identifier& identifier) const
 137         {
 138             initializeIfNeeded(exec);
 139             return entry(identifier);
 140         }
 141
 142     private:
 143         ALWAYS_INLINE const HashEntry* entry(const Identifier& identifier) const
 144         {
 145             ASSERT(table);
 146
 147             const HashEntry* entry = &table[identifier.ustring().rep()->computedHash() & compactHashSizeMask];
 148
 149             if (!entry->key())
 150                 return 0;
 151
 152             do {
 153                 if (entry->key() == identifier.ustring().rep())
 154                     return entry;
 155                 entry = entry->next();
 156             } while (entry);
 157
 158             return 0;
 159         }
 160
 161         // Convert the hash table keys to identifiers.
 162         void createTable(JSGlobalData*) const;
 163     };
 164
 165     void setUpStaticFunctionSlot(ExecState*, const HashEntry*, JSObject* thisObject, const Identifier& propertyName, PropertySlot&);
 166
 167     /**
 168      * This method does it all (looking in the hashtable, checking for function
 169      * overrides, creating the function or retrieving from cache, calling
 170      * getValueProperty in case of a non-function property, forwarding to parent if
 171      * unknown property).
 172      */
 173     template <class ThisImp, class ParentImp>
 174     inline bool getStaticPropertySlot(ExecState* exec, const HashTable* table, ThisImp* thisObj, const Identifier& propertyName, PropertySlot& slot)
 175     {
 176         const HashEntry* entry = table->entry(exec, propertyName);
 177
 178         if (!entry) // not found, forward to parent
 179             return thisObj->ParentImp::getOwnPropertySlot(exec, propertyName, slot);
 180
 181         if (entry->attributes() & Function)
 182             setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
 183         else
 184             slot.setCustom(thisObj, entry->propertyGetter());
 185
 186         return true;
 187     }
 188
 189     /**
 190      * Simplified version of getStaticPropertySlot in case there are only functions.
 191      * Using this instead of getStaticPropertySlot allows 'this' to avoid implementing
 192      * a dummy getValueProperty.
 193      */
 194     template <class ParentImp>
 195     inline bool getStaticFunctionSlot(ExecState* exec, const HashTable* table, JSObject* thisObj, const Identifier& propertyName, PropertySlot& slot)
 196     {
 197         if (static_cast<ParentImp*>(thisObj)->ParentImp::getOwnPropertySlot(exec, propertyName, slot))
 198             return true;
 199
 200         const HashEntry* entry = table->entry(exec, propertyName);
 201         if (!entry)
 202             return false;
 203
 204         setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
 205         return true;
 206     }
 207
 208     /**
 209      * Simplified version of getStaticPropertySlot in case there are no functions, only "values".
 210      * Using this instead of getStaticPropertySlot removes the need for a FuncImp class.
 211      */
 212     template <class ThisImp, class ParentImp>
 213     inline bool getStaticValueSlot(ExecState* exec, const HashTable* table, ThisImp* thisObj, const Identifier& propertyName, PropertySlot& slot)
 214     {
 215         const HashEntry* entry = table->entry(exec, propertyName);
 216
 217         if (!entry) // not found, forward to parent
 218             return thisObj->ParentImp::getOwnPropertySlot(exec, propertyName, slot);
 219
 220         ASSERT(!(entry->attributes() & Function));
 221
 222         slot.setCustom(thisObj, entry->propertyGetter());
 223         return true;
 224     }
 225
 226     /**
 227      * This one is for "put".
 228      * It looks up a hash entry for the property to be set.  If an entry
 229      * is found it sets the value and returns true, else it returns false.
 230      */
 231     template <class ThisImp>
 232     inline bool lookupPut(ExecState* exec, const Identifier& propertyName, JSValue value, const HashTable* table, ThisImp* thisObj)
 233     {
 234         const HashEntry* entry = table->entry(exec, propertyName);
 235
 236         if (!entry)
 237             return false;
 238
 239         if (entry->attributes() & Function) { // function: put as override property
 240             if (LIKELY(value.isCell()))
 241                 thisObj->putDirectFunction(propertyName, value.asCell());
 242             else
 243                 thisObj->putDirect(propertyName, value);
 244         } else if (!(entry->attributes() & ReadOnly))
 245             entry->propertyPutter()(exec, thisObj, value);
 246
 247         return true;
 248     }
 249
 250     /**
 251      * This one is for "put".
 252      * It calls lookupPut<ThisImp>() to set the value.  If that call
 253      * returns false (meaning no entry in the hash table was found),
 254      * then it calls put() on the ParentImp class.
 255      */
 256     template <class ThisImp, class ParentImp>
 257     inline void lookupPut(ExecState* exec, const Identifier& propertyName, JSValue value, const HashTable* table, ThisImp* thisObj, PutPropertySlot& slot)
 258     {
 259         if (!lookupPut<ThisImp>(exec, propertyName, value, table, thisObj))
 260             thisObj->ParentImp::put(exec, propertyName, value, slot); // not found: forward to parent
 261     }
 262
 263 } // namespace JSC
 264
 265 #endif // Lookup_h