Lookup.h   [plain text]

/*
 *  Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
 *  Copyright (C) 2003, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#ifndef Lookup_h
#define Lookup_h

#include "BatchedTransitionOptimizer.h"
#include "CallFrame.h"
#include "CustomGetterSetter.h"
#include "Identifier.h"
#include "IdentifierInlines.h"
#include "Intrinsic.h"
#include "JSGlobalObject.h"
#include "PropertySlot.h"
#include "PutPropertySlot.h"
#include <wtf/Assertions.h>

namespace JSC {
    struct CompactHashIndex {
        const int16_t value;
        const int16_t next;
    };

    // FIXME: There is no reason this get function can't be simpler.
    // ie. typedef JSValue (*GetFunction)(ExecState*, JSObject* baseObject)
    typedef PropertySlot::GetValueFunc GetFunction;
    typedef PutPropertySlot::PutValueFunc PutFunction;
    typedef FunctionExecutable* (*BuiltinGenerator)(VM&);

    // Hash table generated by the create_hash_table script.
    struct HashTableValue {
        const char* m_key; // property name
        unsigned m_attributes; // JSObject attributes
        Intrinsic m_intrinsic;
        intptr_t m_value1;
        intptr_t m_value2;

        unsigned attributes() const { return m_attributes; }

        Intrinsic intrinsic() const { ASSERT(m_attributes & Function); return m_intrinsic; }
        BuiltinGenerator builtinGenerator() const { ASSERT(m_attributes & Builtin); return reinterpret_cast<BuiltinGenerator>(m_value1); }
        NativeFunction function() const { ASSERT(m_attributes & Function); return reinterpret_cast<NativeFunction>(m_value1); }
        unsigned char functionLength() const { ASSERT(m_attributes & Function); return static_cast<unsigned char>(m_value2); }

        GetFunction propertyGetter() const { ASSERT(!(m_attributes & BuiltinOrFunctionOrConstant)); return reinterpret_cast<GetFunction>(m_value1); }
        PutFunction propertyPutter() const { ASSERT(!(m_attributes & BuiltinOrFunctionOrConstant)); return reinterpret_cast<PutFunction>(m_value2); }

        intptr_t constantInteger() const { ASSERT(m_attributes & ConstantInteger); return m_value1; }

        intptr_t lexerValue() const { ASSERT(!m_attributes); return m_value1; }
    };

    struct HashTable {
        mutable int numberOfValues;
        int indexMask;
        bool hasSetterOrReadonlyProperties;

        const HashTableValue* values; // Fixed values generated by script.
        mutable const char** keys; // Table allocated at runtime.
        const CompactHashIndex* index;

        ALWAYS_INLINE HashTable copy() const
        {
            // Don't copy dynamic table since it's thread specific.
            HashTable result = { numberOfValues, indexMask, hasSetterOrReadonlyProperties, values, 0, index };
            return result;
        }

        ALWAYS_INLINE void initializeIfNeeded(VM& vm) const
        {
            if (!keys)
                createTable(vm);
        }

        ALWAYS_INLINE void initializeIfNeeded(ExecState* exec) const
        {
            if (!keys)
                createTable(exec->vm());
        }

        JS_EXPORT_PRIVATE void deleteTable() const;

        // Find an entry in the table, and return the entry.
        ALWAYS_INLINE const HashTableValue* entry(VM& vm, PropertyName identifier) const
        {
            initializeIfNeeded(vm);
            return entry(identifier);
        }

        ALWAYS_INLINE const HashTableValue* entry(ExecState* exec, PropertyName identifier) const
        {
            initializeIfNeeded(exec);
            return entry(identifier);
        }

        class ConstIterator {
        public:
            ConstIterator(const HashTable* table, int position)
                : m_table(table)
                , m_position(position)
            {
                skipInvalidKeys();
            }

            const HashTableValue* value()
            {
                return &m_table->values[m_position];
            }

            const char* key()
            {
                return m_table->keys[m_position];
            }

            const HashTableValue* operator->()
            {
                return value();
            }

            bool operator!=(const ConstIterator& other)
            {
                ASSERT(m_table == other.m_table);
                return m_position != other.m_position;
            }
            
            ConstIterator& operator++()
            {
                ASSERT(m_position < m_table->numberOfValues);
                ++m_position;
                skipInvalidKeys();
                return *this;
            }

        private:
            void skipInvalidKeys()
            {
                ASSERT(m_position <= m_table->numberOfValues);
                while (m_position < m_table->numberOfValues && !m_table->keys[m_position])
                    ++m_position;
                ASSERT(m_position <= m_table->numberOfValues);
            }
            
            const HashTable* m_table;
            int m_position;
        };

        ConstIterator begin(VM& vm) const
        {
            initializeIfNeeded(vm);
            return ConstIterator(this, 0);
        }
        ConstIterator end(VM& vm) const
        {
            initializeIfNeeded(vm);
            return ConstIterator(this, numberOfValues);
        }

    private:
        ALWAYS_INLINE const HashTableValue* entry(PropertyName propertyName) const
        {
            StringImpl* impl = propertyName.uid();
            if (!impl)
                return 0;
        
            ASSERT(keys);

            int indexEntry = impl->existingHash() & indexMask;
            int valueIndex = index[indexEntry].value;
            if (valueIndex == -1)
                return 0;

            while (true) {
                if (WTF::equal(impl, keys[valueIndex]))
                    return &values[valueIndex];

                indexEntry = index[indexEntry].next;
                if (indexEntry == -1)
                    return nullptr;
                valueIndex = index[indexEntry].value;
                ASSERT(valueIndex != -1);
            };
        }

        // Convert the hash table keys to identifiers.
        JS_EXPORT_PRIVATE void createTable(VM&) const;
    };

    JS_EXPORT_PRIVATE bool setUpStaticFunctionSlot(ExecState*, const HashTableValue*, JSObject* thisObject, PropertyName, PropertySlot&);

    /**
     * This method does it all (looking in the hashtable, checking for function
     * overrides, creating the function or retrieving from cache, calling
     * getValueProperty in case of a non-function property, forwarding to parent if
     * unknown property).
     */
    template <class ThisImp, class ParentImp>
    inline bool getStaticPropertySlot(ExecState* exec, const HashTable& table, ThisImp* thisObj, PropertyName propertyName, PropertySlot& slot)
    {
        const HashTableValue* entry = table.entry(exec, propertyName);

        if (!entry) // not found, forward to parent
            return ParentImp::getOwnPropertySlot(thisObj, exec, propertyName, slot);

        if (entry->attributes() & BuiltinOrFunction)
            return setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);

        if (entry->attributes() & ConstantInteger) {
            slot.setValue(thisObj, entry->attributes(), jsNumber(entry->constantInteger()));
            return true;
        }
    
        slot.setCacheableCustom(thisObj, entry->attributes(), entry->propertyGetter());
        return true;
    }

    /**
     * Simplified version of getStaticPropertySlot in case there are only functions.
     * Using this instead of getStaticPropertySlot allows 'this' to avoid implementing
     * a dummy getValueProperty.
     */
    template <class ParentImp>
    inline bool getStaticFunctionSlot(ExecState* exec, const HashTable& table, JSObject* thisObj, PropertyName propertyName, PropertySlot& slot)
    {
        if (ParentImp::getOwnPropertySlot(thisObj, exec, propertyName, slot))
            return true;

        const HashTableValue* entry = table.entry(exec, propertyName);
        if (!entry)
            return false;

        return setUpStaticFunctionSlot(exec, entry, thisObj, propertyName, slot);
    }

    /**
     * Simplified version of getStaticPropertySlot in case there are no functions, only "values".
     * Using this instead of getStaticPropertySlot removes the need for a FuncImp class.
     */
    template <class ThisImp, class ParentImp>
    inline bool getStaticValueSlot(ExecState* exec, const HashTable& table, ThisImp* thisObj, PropertyName propertyName, PropertySlot& slot)
    {
        const HashTableValue* entry = table.entry(exec, propertyName);

        if (!entry) // not found, forward to parent
            return ParentImp::getOwnPropertySlot(thisObj, exec, propertyName, slot);

        ASSERT(!(entry->attributes() & BuiltinOrFunction));

        if (entry->attributes() & ConstantInteger) {
            slot.setValue(thisObj, entry->attributes(), jsNumber(entry->constantInteger()));
            return true;
        }

        slot.setCacheableCustom(thisObj, entry->attributes(), entry->propertyGetter());
        return true;
    }

    inline void putEntry(ExecState* exec, const HashTableValue* entry, JSObject* base, PropertyName propertyName, JSValue value, PutPropertySlot& slot)
    {
        // If this is a function put it as an override property.
        if (entry->attributes() & BuiltinOrFunction) {
            if (JSObject* thisObject = jsDynamicCast<JSObject*>(slot.thisValue()))
                thisObject->putDirect(exec->vm(), propertyName, value);
        } else if (!(entry->attributes() & ReadOnly)) {
            entry->propertyPutter()(exec, base, JSValue::encode(slot.thisValue()), JSValue::encode(value));
            slot.setCustomProperty(base, entry->propertyPutter());
        } else if (slot.isStrictMode())
            throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
    }

    /**
     * This one is for "put".
     * It looks up a hash entry for the property to be set.  If an entry
     * is found it sets the value and returns true, else it returns false.
     */
    inline bool lookupPut(ExecState* exec, PropertyName propertyName, JSObject* base, JSValue value, const HashTable& table, PutPropertySlot& slot)
    {
        const HashTableValue* entry = table.entry(exec, propertyName);

        if (!entry)
            return false;

        putEntry(exec, entry, base, propertyName, value, slot);
        return true;
    }

    template<unsigned numberOfValues>
    inline void reifyStaticProperties(VM& vm, const HashTableValue (&values)[numberOfValues], JSObject& thisObj)
    {
        BatchedTransitionOptimizer transitionOptimizer(vm, &thisObj);
        for (auto& value : values) {
            if (!value.m_key)
                continue;                
        
            Identifier propertyName(&vm, reinterpret_cast<const LChar*>(value.m_key), strlen(value.m_key));
            if (value.attributes() & Builtin) {
                thisObj.putDirectBuiltinFunction(vm, thisObj.globalObject(), propertyName, value.builtinGenerator()(vm), value.attributes());
                continue;
            }

            if (value.attributes() & Function) {
                thisObj.putDirectNativeFunction(vm, thisObj.globalObject(), propertyName, value.functionLength(),
                    value.function(), value.intrinsic(), value.attributes());
                continue;
            }

            if (value.attributes() & ConstantInteger) {
                thisObj.putDirect(vm, propertyName, jsNumber(value.constantInteger()), value.attributes());
                continue;
            }

            if (value.attributes() & Accessor) {
                RELEASE_ASSERT_NOT_REACHED();
                continue;
            }

            CustomGetterSetter* customGetterSetter = CustomGetterSetter::create(vm, value.propertyGetter(), value.propertyPutter());
            thisObj.putDirectCustomAccessor(vm, propertyName, customGetterSetter, value.attributes());
        }
    }

} // namespace JSC

#endif // Lookup_h