V8Binding.h   [plain text]

/*
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#ifndef V8Binding_h
#define V8Binding_h

#include "BindingSecurity.h"
#include "MathExtras.h"
#include "PlatformString.h"
#include "V8DOMWrapper.h"
#include <wtf/text/AtomicString.h>

#include <v8.h>

namespace WebCore {

    class DOMStringList;
    class EventListener;
    class EventTarget;

    // FIXME: Remove V8Binding.
    class V8Binding {
    };
    typedef BindingSecurity<V8Binding> V8BindingSecurity;

    enum ExternalMode {
        Externalize,
        DoNotExternalize
    };

    template <typename StringType>
    StringType v8StringToWebCoreString(v8::Handle<v8::String> v8String, ExternalMode external);

    // Convert v8 types to a WTF::String. If the V8 string is not already
    // an external string then it is transformed into an external string at this
    // point to avoid repeated conversions.
    inline String v8StringToWebCoreString(v8::Handle<v8::String> v8String)
    {
        return v8StringToWebCoreString<String>(v8String, Externalize);
    }
    String v8NonStringValueToWebCoreString(v8::Handle<v8::Value>);
    String v8ValueToWebCoreString(v8::Handle<v8::Value> value);

    // Convert v8 types to a WTF::AtomicString.
    inline AtomicString v8StringToAtomicWebCoreString(v8::Handle<v8::String> v8String)
    {
        return v8StringToWebCoreString<AtomicString>(v8String, Externalize);
    }
    AtomicString v8NonStringValueToAtomicWebCoreString(v8::Handle<v8::Value>);
    AtomicString v8ValueToAtomicWebCoreString(v8::Handle<v8::Value> value);

    // Note: RefPtr is a must as we cache by StringImpl* equality, not identity
    // hence lastStringImpl might be not a key of the cache (in sense of identity)
    // and hence it's not refed on addition.
    extern RefPtr<StringImpl> lastStringImpl;
    extern v8::Persistent<v8::String> lastV8String;
    v8::Local<v8::String> v8ExternalStringSlow(StringImpl* stringImpl);

    // Return a V8 external string that shares the underlying buffer with the given
    // WebCore string. The reference counting mechanism is used to keep the
    // underlying buffer alive while the string is still live in the V8 engine.
    inline v8::Local<v8::String> v8ExternalString(const String& string)
    {
        StringImpl* stringImpl = string.impl();
        if (!stringImpl)
            return v8::String::Empty();

        if (lastStringImpl.get() == stringImpl) {
            ASSERT(!lastV8String.IsNearDeath());
            ASSERT(!lastV8String.IsEmpty());
            return v8::Local<v8::String>::New(lastV8String);
        }

        return v8ExternalStringSlow(stringImpl);
    }

    // Convert a string to a V8 string.
    inline v8::Handle<v8::String> v8String(const String& string)
    {
        return v8ExternalString(string);
    }

    // Enables caching v8 wrappers created for WTF::StringImpl.  Currently this cache requires
    // all the calls (both to convert WTF::String to v8::String and to GC the handle)
    // to be performed on the main thread.
    void enableStringImplCache();

    // Convert a value to a 32-bit integer.  The conversion fails if the
    // value cannot be converted to an integer or converts to nan or to an infinity.
    int toInt32(v8::Handle<v8::Value> value, bool& ok);

    // Convert a value to a 32-bit integer assuming the conversion cannot fail.
    inline int toInt32(v8::Handle<v8::Value> value)
    {
        bool ok;
        return toInt32(value, ok);
    }

    // Convert a value to a 32-bit unsigned integer.  The conversion fails if the
    // value cannot be converted to an unsigned integer or converts to nan or to an infinity.
    uint32_t toUInt32(v8::Handle<v8::Value> value, bool& ok);

    // Convert a value to a 32-bit unsigned integer assuming the conversion cannot fail.
    inline uint32_t toUInt32(v8::Handle<v8::Value> value)
    {
        bool ok;
        return toUInt32(value, ok);
    }

    inline float toFloat(v8::Local<v8::Value> value)
    {
        return static_cast<float>(value->NumberValue());
    }

    inline long long toInt64(v8::Local<v8::Value> value)
    {
        return static_cast<long long>(value->IntegerValue());
    }

    // FIXME: Drop this in favor of the type specific v8ValueToWebCoreString when we rework the code generation.
    inline String toWebCoreString(v8::Handle<v8::Value> object)
    {
        return v8ValueToWebCoreString(object);
    }

    String toWebCoreString(const v8::Arguments&, int index);

    // The string returned by this function is still owned by the argument
    // and will be deallocated when the argument is deallocated.
    inline const uint16_t* fromWebCoreString(const String& str)
    {
        return reinterpret_cast<const uint16_t*>(str.characters());
    }

    bool isUndefinedOrNull(v8::Handle<v8::Value> value);

    v8::Handle<v8::Boolean> v8Boolean(bool value);

    String toWebCoreStringWithNullCheck(v8::Handle<v8::Value> value);

    AtomicString toAtomicWebCoreStringWithNullCheck(v8::Handle<v8::Value> value);

    String toWebCoreStringWithNullOrUndefinedCheck(v8::Handle<v8::Value> value);

    v8::Handle<v8::String> v8UndetectableString(const String& str);

    v8::Handle<v8::Value> v8StringOrNull(const String& str);

    v8::Handle<v8::Value> v8StringOrUndefined(const String& str);

    v8::Handle<v8::Value> v8StringOrFalse(const String& str);

    double toWebCoreDate(v8::Handle<v8::Value> object);

    v8::Handle<v8::Value> v8DateOrNull(double value);

    v8::Persistent<v8::FunctionTemplate> createRawTemplate();

    struct BatchedAttribute;
    struct BatchedCallback;

    v8::Local<v8::Signature> configureTemplate(v8::Persistent<v8::FunctionTemplate>,
                                               const char* interfaceName,
                                               v8::Persistent<v8::FunctionTemplate> parentClass,
                                               int fieldCount,
                                               const BatchedAttribute*,
                                               size_t attributeCount,
                                               const BatchedCallback*,
                                               size_t callbackCount);

    v8::Handle<v8::Value> getElementStringAttr(const v8::AccessorInfo&,
                                               const QualifiedName&);
    void setElementStringAttr(const v8::AccessorInfo&,
                              const QualifiedName&,
                              v8::Local<v8::Value>);


    v8::Persistent<v8::String> getToStringName();
    v8::Persistent<v8::FunctionTemplate> getToStringTemplate();

    String int32ToWebCoreString(int value);

    PassRefPtr<DOMStringList> v8ValueToWebCoreDOMStringList(v8::Handle<v8::Value>);

    class V8ParameterBase {
    public:
        operator String() { return toString<String>(); }
        operator AtomicString() { return toString<AtomicString>(); }

    protected:
        V8ParameterBase(v8::Local<v8::Value> object) : m_v8Object(object), m_mode(Externalize), m_string() { }

        bool prepareBase()
        {
            if (LIKELY(m_v8Object->IsString()))
                return true;

            if (LIKELY(m_v8Object->IsInt32())) {
                setString(int32ToWebCoreString(m_v8Object->Int32Value()));
                return true;
            }

            m_mode = DoNotExternalize;
            v8::TryCatch block;
            m_v8Object = m_v8Object->ToString();
            // Handle the case where an exception is thrown as part of invoking toString on the object.
            if (block.HasCaught()) {
                block.ReThrow();
                return false;
            }

            // This path is unexpected.  However there is hypothesis that it
            // might be combination of v8 and v8 bindings bugs.  For now
            // just bailout as we'll crash if attempt to convert empty handle into a string.
            if (m_v8Object.IsEmpty()) {
                ASSERT_NOT_REACHED();
                return false;
            }

            return true;
        }

        v8::Local<v8::Value> object() { return m_v8Object; }

        void setString(String string)
        {
            m_string = string;
            m_v8Object.Clear(); // To signal that String is ready.
        }

     private:
        v8::Local<v8::Value> m_v8Object;
        ExternalMode m_mode;
        String m_string;

        template <class StringType>
        StringType toString()
        {
            if (LIKELY(!m_v8Object.IsEmpty()))
                return v8StringToWebCoreString<StringType>(m_v8Object.As<v8::String>(), m_mode);

            return StringType(m_string);
        }
    };

    // V8Parameter is an adapter class that converts V8 values to Strings
    // or AtomicStrings as appropriate, using multiple typecast operators.
    enum V8ParameterMode {
        DefaultMode,
        WithNullCheck,
        WithUndefinedOrNullCheck
    };
    template <V8ParameterMode MODE = DefaultMode>
    class V8Parameter: public V8ParameterBase {
    public:
        V8Parameter(v8::Local<v8::Value> object) : V8ParameterBase(object) { }
        V8Parameter(v8::Local<v8::Value> object, bool) : V8ParameterBase(object) { prepare(); }

        bool prepare();
    };

    template<> inline bool V8Parameter<DefaultMode>::prepare()
    {
        return V8ParameterBase::prepareBase();
    }

    template<> inline bool V8Parameter<WithNullCheck>::prepare()
    {
        if (object()->IsNull()) {
            setString(String());
            return true;
        }

        return V8ParameterBase::prepareBase();
    }

    template<> inline bool V8Parameter<WithUndefinedOrNullCheck>::prepare()
    {
        if (object()->IsNull() || object()->IsUndefined()) {
            setString(String());
            return true;
        }

        return V8ParameterBase::prepareBase();
    }

} // namespace WebCore

#endif // V8Binding_h