qtdeclarative/src/qml/jsruntime/qv4engine_p.h

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**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtQml module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
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** accordance with the commercial license agreement provided with the
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** information use the contact form at https://www.qt.io/contact-us.
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** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
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#ifndef QV4ENGINE_H
#define QV4ENGINE_H

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//

#include "qv4global_p.h"
#include "private/qv4isel_p.h"
#include "qv4managed_p.h"
#include "qv4context_p.h"
#include "qv4runtimeapi_p.h"
#include <private/qintrusivelist_p.h>

#ifndef V4_BOOTSTRAP
#  include <private/qv8engine_p.h>
#endif

namespace WTF {
class BumpPointerAllocator;
class PageAllocation;
}

QT_BEGIN_NAMESPACE

class QV8Engine;
class QQmlError;
class QJSEngine;
class QQmlEngine;
class QQmlContextData;

namespace QV4 {
namespace Debugging {
class Debugger;
} // namespace Debugging
namespace Profiling {
class Profiler;
} // namespace Profiling
namespace CompiledData {
struct CompilationUnit;
}

struct InternalClass;
struct InternalClassPool;

struct Q_QML_EXPORT ExecutionEngine
{
private:
    static qint32 maxCallDepth;

    friend struct ExecutionContextSaver;
    friend struct ExecutionContext;
    friend struct Heap::ExecutionContext;
public:
    Heap::ExecutionContext *current;

    Value *jsStackTop;
    quint8 hasException;
    quint8 writeBarrierActive = false;
    quint16 unused = 0;
    qint32 callDepth;

    MemoryManager *memoryManager;
    ExecutableAllocator *executableAllocator;
    ExecutableAllocator *regExpAllocator;
    QScopedPointer<EvalISelFactory> iselFactory;

    ExecutionContext *currentContext;

    Value *jsStackLimit;

    Runtime runtime;

    WTF::BumpPointerAllocator *bumperPointerAllocator; // Used by Yarr Regex engine.

    enum { JSStackLimit = 4*1024*1024 };
    WTF::PageAllocation *jsStack;
    Value *jsStackBase;

    void pushForGC(Heap::Base *m) {
        *jsStackTop = m;
        ++jsStackTop;
    }
    Heap::Base *popForGC() {
        --jsStackTop;
        return jsStackTop->heapObject();
    }

    QML_NEARLY_ALWAYS_INLINE Value *jsAlloca(int nValues) {
        Value *ptr = jsStackTop;
        jsStackTop = ptr + nValues;
        for (int i = 0; i < nValues; ++i)
            ptr[i] = Primitive::undefinedValue();
        return ptr;
    }

    IdentifierTable *identifierTable;

    Object *globalObject;

    Function *globalCode;

#ifdef V4_BOOTSTRAP
    QJSEngine *jsEngine() const;
    QQmlEngine *qmlEngine() const;
#else // !V4_BOOTSTRAP
    QJSEngine *jsEngine() const { return v8Engine->publicEngine(); }
    QQmlEngine *qmlEngine() const { return v8Engine ? v8Engine->engine() : nullptr; }
#endif // V4_BOOTSTRAP
    QV8Engine *v8Engine;

    enum JSObjects {
        RootContext,
        IntegerNull, // Has to come after the RootContext to make the context stack safe
        ObjectProto,
        ArrayProto,
        PropertyListProto,
        StringProto,
        NumberProto,
        BooleanProto,
        DateProto,
        FunctionProto,
        RegExpProto,
        ErrorProto,
        EvalErrorProto,
        RangeErrorProto,
        ReferenceErrorProto,
        SyntaxErrorProto,
        TypeErrorProto,
        URIErrorProto,
        VariantProto,
        SequenceProto,
        ArrayBufferProto,
        DataViewProto,
        ValueTypeProto,
        SignalHandlerProto,

        Object_Ctor,
        String_Ctor,
        Number_Ctor,
        Boolean_Ctor,
        Array_Ctor,
        Function_Ctor,
        Date_Ctor,
        RegExp_Ctor,
        Error_Ctor,
        EvalError_Ctor,
        RangeError_Ctor,
        ReferenceError_Ctor,
        SyntaxError_Ctor,
        TypeError_Ctor,
        URIError_Ctor,
        ArrayBuffer_Ctor,
        DataView_Ctor,

        Eval_Function,
        GetStack_Function,
        ThrowerObject,
        NJSObjects
    };
    Value *jsObjects;
    enum { NTypedArrayTypes = 9 }; // == TypedArray::NValues, avoid header dependency

    GlobalContext *rootContext() const { return reinterpret_cast<GlobalContext *>(jsObjects + RootContext); }
    FunctionObject *objectCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + Object_Ctor); }
    FunctionObject *stringCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + String_Ctor); }
    FunctionObject *numberCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + Number_Ctor); }
    FunctionObject *booleanCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + Boolean_Ctor); }
    FunctionObject *arrayCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + Array_Ctor); }
    FunctionObject *functionCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + Function_Ctor); }
    FunctionObject *dateCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + Date_Ctor); }
    FunctionObject *regExpCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + RegExp_Ctor); }
    FunctionObject *errorCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + Error_Ctor); }
    FunctionObject *evalErrorCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + EvalError_Ctor); }
    FunctionObject *rangeErrorCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + RangeError_Ctor); }
    FunctionObject *referenceErrorCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + ReferenceError_Ctor); }
    FunctionObject *syntaxErrorCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + SyntaxError_Ctor); }
    FunctionObject *typeErrorCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + TypeError_Ctor); }
    FunctionObject *uRIErrorCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + URIError_Ctor); }
    FunctionObject *arrayBufferCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + ArrayBuffer_Ctor); }
    FunctionObject *dataViewCtor() const { return reinterpret_cast<FunctionObject *>(jsObjects + DataView_Ctor); }
    FunctionObject *typedArrayCtors;

    Object *objectPrototype() const { return reinterpret_cast<Object *>(jsObjects + ObjectProto); }
    Object *arrayPrototype() const { return reinterpret_cast<Object *>(jsObjects + ArrayProto); }
    Object *propertyListPrototype() const { return reinterpret_cast<Object *>(jsObjects + PropertyListProto); }
    Object *stringPrototype() const { return reinterpret_cast<Object *>(jsObjects + StringProto); }
    Object *numberPrototype() const { return reinterpret_cast<Object *>(jsObjects + NumberProto); }
    Object *booleanPrototype() const { return reinterpret_cast<Object *>(jsObjects + BooleanProto); }
    Object *datePrototype() const { return reinterpret_cast<Object *>(jsObjects + DateProto); }
    Object *functionPrototype() const { return reinterpret_cast<Object *>(jsObjects + FunctionProto); }
    Object *regExpPrototype() const { return reinterpret_cast<Object *>(jsObjects + RegExpProto); }
    Object *errorPrototype() const { return reinterpret_cast<Object *>(jsObjects + ErrorProto); }
    Object *evalErrorPrototype() const { return reinterpret_cast<Object *>(jsObjects + EvalErrorProto); }
    Object *rangeErrorPrototype() const { return reinterpret_cast<Object *>(jsObjects + RangeErrorProto); }
    Object *referenceErrorPrototype() const { return reinterpret_cast<Object *>(jsObjects + ReferenceErrorProto); }
    Object *syntaxErrorPrototype() const { return reinterpret_cast<Object *>(jsObjects + SyntaxErrorProto); }
    Object *typeErrorPrototype() const { return reinterpret_cast<Object *>(jsObjects + TypeErrorProto); }
    Object *uRIErrorPrototype() const { return reinterpret_cast<Object *>(jsObjects + URIErrorProto); }
    Object *variantPrototype() const { return reinterpret_cast<Object *>(jsObjects + VariantProto); }
    Object *sequencePrototype() const { return reinterpret_cast<Object *>(jsObjects + SequenceProto); }

    Object *arrayBufferPrototype() const { return reinterpret_cast<Object *>(jsObjects + ArrayBufferProto); }
    Object *dataViewPrototype() const { return reinterpret_cast<Object *>(jsObjects + DataViewProto); }
    Object *typedArrayPrototype;

    Object *valueTypeWrapperPrototype() const { return reinterpret_cast<Object *>(jsObjects + ValueTypeProto); }
    Object *signalHandlerPrototype() const { return reinterpret_cast<Object *>(jsObjects + SignalHandlerProto); }

    InternalClassPool *classPool;
    InternalClass *emptyClass;

    InternalClass *arrayClass;
    InternalClass *stringClass;

    InternalClass *functionClass;
    InternalClass *scriptFunctionClass;
    InternalClass *protoClass;

    InternalClass *regExpExecArrayClass;
    InternalClass *regExpObjectClass;

    InternalClass *argumentsObjectClass;
    InternalClass *strictArgumentsObjectClass;

    InternalClass *errorClass;
    InternalClass *errorClassWithMessage;
    InternalClass *errorProtoClass;

    EvalFunction *evalFunction() const { return reinterpret_cast<EvalFunction *>(jsObjects + Eval_Function); }
    FunctionObject *getStackFunction() const { return reinterpret_cast<FunctionObject *>(jsObjects + GetStack_Function); }
    FunctionObject *thrower() const { return reinterpret_cast<FunctionObject *>(jsObjects + ThrowerObject); }

    Property *argumentsAccessors;
    int nArgumentsAccessors;

    enum JSStrings {
        String_Empty,
        String_undefined,
        String_null,
        String_true,
        String_false,
        String_boolean,
        String_number,
        String_string,
        String_object,
        String_function,
        String_length,
        String_prototype,
        String_constructor,
        String_arguments,
        String_caller,
        String_callee,
        String_this,
        String___proto__,
        String_enumerable,
        String_configurable,
        String_writable,
        String_value,
        String_get,
        String_set,
        String_eval,
        String_uintMax,
        String_name,
        String_index,
        String_input,
        String_toString,
        String_destroy,
        String_valueOf,
        String_byteLength,
        String_byteOffset,
        String_buffer,
        String_lastIndex,
        NJSStrings
    };
    Value *jsStrings;

    String *id_empty() const { return reinterpret_cast<String *>(jsStrings + String_Empty); }
    String *id_undefined() const { return reinterpret_cast<String *>(jsStrings + String_undefined); }
    String *id_null() const { return reinterpret_cast<String *>(jsStrings + String_null); }
    String *id_true() const { return reinterpret_cast<String *>(jsStrings + String_true); }
    String *id_false() const { return reinterpret_cast<String *>(jsStrings + String_false); }
    String *id_boolean() const { return reinterpret_cast<String *>(jsStrings + String_boolean); }
    String *id_number() const { return reinterpret_cast<String *>(jsStrings + String_number); }
    String *id_string() const { return reinterpret_cast<String *>(jsStrings + String_string); }
    String *id_object() const { return reinterpret_cast<String *>(jsStrings + String_object); }
    String *id_function() const { return reinterpret_cast<String *>(jsStrings + String_function); }
    String *id_length() const { return reinterpret_cast<String *>(jsStrings + String_length); }
    String *id_prototype() const { return reinterpret_cast<String *>(jsStrings + String_prototype); }
    String *id_constructor() const { return reinterpret_cast<String *>(jsStrings + String_constructor); }
    String *id_arguments() const { return reinterpret_cast<String *>(jsStrings + String_arguments); }
    String *id_caller() const { return reinterpret_cast<String *>(jsStrings + String_caller); }
    String *id_callee() const { return reinterpret_cast<String *>(jsStrings + String_callee); }
    String *id_this() const { return reinterpret_cast<String *>(jsStrings + String_this); }
    String *id___proto__() const { return reinterpret_cast<String *>(jsStrings + String___proto__); }
    String *id_enumerable() const { return reinterpret_cast<String *>(jsStrings + String_enumerable); }
    String *id_configurable() const { return reinterpret_cast<String *>(jsStrings + String_configurable); }
    String *id_writable() const { return reinterpret_cast<String *>(jsStrings + String_writable); }
    String *id_value() const { return reinterpret_cast<String *>(jsStrings + String_value); }
    String *id_get() const { return reinterpret_cast<String *>(jsStrings + String_get); }
    String *id_set() const { return reinterpret_cast<String *>(jsStrings + String_set); }
    String *id_eval() const { return reinterpret_cast<String *>(jsStrings + String_eval); }
    String *id_uintMax() const { return reinterpret_cast<String *>(jsStrings + String_uintMax); }
    String *id_name() const { return reinterpret_cast<String *>(jsStrings + String_name); }
    String *id_index() const { return reinterpret_cast<String *>(jsStrings + String_index); }
    String *id_input() const { return reinterpret_cast<String *>(jsStrings + String_input); }
    String *id_toString() const { return reinterpret_cast<String *>(jsStrings + String_toString); }
    String *id_destroy() const { return reinterpret_cast<String *>(jsStrings + String_destroy); }
    String *id_valueOf() const { return reinterpret_cast<String *>(jsStrings + String_valueOf); }
    String *id_byteLength() const { return reinterpret_cast<String *>(jsStrings + String_byteLength); }
    String *id_byteOffset() const { return reinterpret_cast<String *>(jsStrings + String_byteOffset); }
    String *id_buffer() const { return reinterpret_cast<String *>(jsStrings + String_buffer); }
    String *id_lastIndex() const { return reinterpret_cast<String *>(jsStrings + String_lastIndex); }

    QSet<CompiledData::CompilationUnit*> compilationUnits;

    quint32 m_engineId;

    RegExpCache *regExpCache;

    // Scarce resources are "exceptionally high cost" QVariant types where allowing the
    // normal JavaScript GC to clean them up is likely to lead to out-of-memory or other
    // out-of-resource situations.  When such a resource is passed into JavaScript we
    // add it to the scarceResources list and it is destroyed when we return from the
    // JavaScript execution that created it.  The user can prevent this behavior by
    // calling preserve() on the object which removes it from this scarceResource list.
    class ScarceResourceData {
    public:
        ScarceResourceData(const QVariant &data = QVariant()) : data(data) {}
        QVariant data;
        QIntrusiveListNode node;
    };
    QIntrusiveList<ScarceResourceData, &ScarceResourceData::node> scarceResources;

    // Normally the JS wrappers for QObjects are stored in the QQmlData/QObjectPrivate,
    // but any time a QObject is wrapped a second time in another engine, we have to do
    // bookkeeping.
    MultiplyWrappedQObjectMap *m_multiplyWrappedQObjects;

    ExecutionEngine(EvalISelFactory *iselFactory = 0);
    ~ExecutionEngine();

#ifdef QT_NO_QML_DEBUGGER
    QV4::Debugging::Debugger *debugger() const { return nullptr; }
    QV4::Profiling::Profiler *profiler() const { return nullptr; }

    void setDebugger(Debugging::Debugger *) {}
    void setProfiler(Profiling::Profiler *) {}
#else
    QV4::Debugging::Debugger *debugger() const { return m_debugger; }
    QV4::Profiling::Profiler *profiler() const { return m_profiler; }

    void setDebugger(Debugging::Debugger *debugger);
    void setProfiler(Profiling::Profiler *profiler);
#endif // QT_NO_QML_DEBUGGER

    ExecutionContext *pushGlobalContext();
    void pushContext(Heap::ExecutionContext *context);
    void pushContext(ExecutionContext *context);
    void popContext();
    ExecutionContext *parentContext(ExecutionContext *context) const;

    Heap::Object *newObject();
    Heap::Object *newObject(InternalClass *internalClass, Object *prototype);

    Heap::String *newString(const QString &s = QString());
    Heap::String *newIdentifier(const QString &text);

    Heap::Object *newStringObject(const String *string);
    Heap::Object *newNumberObject(double value);
    Heap::Object *newBooleanObject(bool b);

    Heap::ArrayObject *newArrayObject(int count = 0);
    Heap::ArrayObject *newArrayObject(const Value *values, int length);
    Heap::ArrayObject *newArrayObject(const QStringList &list);
    Heap::ArrayObject *newArrayObject(InternalClass *ic, Object *prototype);

    Heap::ArrayBuffer *newArrayBuffer(const QByteArray &array);
    Heap::ArrayBuffer *newArrayBuffer(size_t length);

    Heap::DateObject *newDateObject(const Value &value);
    Heap::DateObject *newDateObject(const QDateTime &dt);
    Heap::DateObject *newDateObjectFromTime(const QTime &t);

    Heap::RegExpObject *newRegExpObject(const QString &pattern, int flags);
    Heap::RegExpObject *newRegExpObject(RegExp *re, bool global);
    Heap::RegExpObject *newRegExpObject(const QRegExp &re);

    Heap::Object *newErrorObject(const Value &value);
    Heap::Object *newSyntaxErrorObject(const QString &message, const QString &fileName, int line, int column);
    Heap::Object *newSyntaxErrorObject(const QString &message);
    Heap::Object *newReferenceErrorObject(const QString &message);
    Heap::Object *newReferenceErrorObject(const QString &message, const QString &fileName, int line, int column);
    Heap::Object *newTypeErrorObject(const QString &message);
    Heap::Object *newRangeErrorObject(const QString &message);
    Heap::Object *newURIErrorObject(const Value &message);

    Heap::Object *newVariantObject(const QVariant &v);

    Heap::Object *newForEachIteratorObject(Object *o);

    Heap::QmlContext *qmlContext() const;
    QObject *qmlScopeObject() const;
    ReturnedValue qmlSingletonWrapper(String *name);
    QQmlContextData *callingQmlContext() const;


    StackTrace stackTrace(int frameLimit = -1) const;
    StackFrame currentStackFrame() const;
    QUrl resolvedUrl(const QString &file);

    void requireArgumentsAccessors(int n);

    void markObjects();

    void initRootContext();

    InternalClass *newClass(const InternalClass &other);

    // Exception handling
    Value *exceptionValue;
    StackTrace exceptionStackTrace;

    ReturnedValue throwError(const Value &value);
    ReturnedValue catchException(StackTrace *trace = 0);

    ReturnedValue throwError(const QString &message);
    ReturnedValue throwSyntaxError(const QString &message);
    ReturnedValue throwSyntaxError(const QString &message, const QString &fileName, int lineNumber, int column);
    ReturnedValue throwTypeError();
    ReturnedValue throwTypeError(const QString &message);
    ReturnedValue throwReferenceError(const Value &value);
    ReturnedValue throwReferenceError(const QString &value, const QString &fileName, int lineNumber, int column);
    ReturnedValue throwRangeError(const Value &value);
    ReturnedValue throwRangeError(const QString &message);
    ReturnedValue throwURIError(const Value &msg);
    ReturnedValue throwUnimplemented(const QString &message);

    // Use only inside catch(...) -- will re-throw if no JS exception
    QQmlError catchExceptionAsQmlError();

    // variant conversions
    QVariant toVariant(const QV4::Value &value, int typeHint, bool createJSValueForObjects = true);
    QV4::ReturnedValue fromVariant(const QVariant &);

    QVariantMap variantMapFromJS(const QV4::Object *o);

    bool metaTypeFromJS(const Value *value, int type, void *data);
    QV4::ReturnedValue metaTypeToJS(int type, const void *data);

    void assertObjectBelongsToEngine(const Heap::Base &baseObject);

    bool checkStackLimits(Scope &scope);

private:
    void failStackLimitCheck(Scope &scope);

#ifndef QT_NO_QML_DEBUGGER
    QV4::Debugging::Debugger *m_debugger;
    QV4::Profiling::Profiler *m_profiler;
#endif
};

// This is a trick to tell the code generators that functions taking a NoThrowContext won't
// throw exceptions and therefore don't need a check after the call.
#ifndef V4_BOOTSTRAP
struct NoThrowEngine : public ExecutionEngine
{
};
#else
struct NoThrowEngine;
#endif


inline void ExecutionEngine::pushContext(Heap::ExecutionContext *context)
{
    Q_ASSERT(currentContext && context);
    Value *v = jsAlloca(2);
    v[0] = Encode(context);
    v[1] = Encode((int)(v - static_cast<Value *>(currentContext)));
    currentContext = static_cast<ExecutionContext *>(v);
    current = currentContext->d();
}

inline void ExecutionEngine::pushContext(ExecutionContext *context)
{
    pushContext(context->d());
}


inline void ExecutionEngine::popContext()
{
    Q_ASSERT(jsStackTop > currentContext);
    QV4::Value *offset = (currentContext + 1);
    Q_ASSERT(offset->isInteger());
    int o = offset->integerValue();
    Q_ASSERT(o);
    currentContext -= o;
    current = currentContext->d();
}

inline ExecutionContext *ExecutionEngine::parentContext(ExecutionContext *context) const
{
    Value *offset = static_cast<Value *>(context) + 1;
    Q_ASSERT(offset->isInteger());
    int o = offset->integerValue();
    return o ? context - o : 0;
}

inline
void Heap::Base::mark(QV4::ExecutionEngine *engine)
{
    Q_ASSERT(inUse());
    if (isMarked())
        return;
#ifndef QT_NO_DEBUG
    engine->assertObjectBelongsToEngine(*this);
#endif
    setMarkBit();
    engine->pushForGC(this);
}

inline void Value::mark(ExecutionEngine *e)
{
    Heap::Base *o = heapObject();
    if (o)
        o->mark(e);
}

#define CHECK_STACK_LIMITS(v4, scope) if ((v4)->checkStackLimits(scope)) return; \
    ExecutionEngineCallDepthRecorder _executionEngineCallDepthRecorder(v4);

struct ExecutionEngineCallDepthRecorder
{
    ExecutionEngine *ee;

    ExecutionEngineCallDepthRecorder(ExecutionEngine *e): ee(e) { ++ee->callDepth; }
    ~ExecutionEngineCallDepthRecorder() { --ee->callDepth; }
};

inline bool ExecutionEngine::checkStackLimits(Scope &scope)
{
    if (Q_UNLIKELY((jsStackTop > jsStackLimit) || (callDepth >= maxCallDepth))) {
        failStackLimitCheck(scope);
        return true;
    }

    return false;
}

} // namespace QV4

QT_END_NAMESPACE

#endif // QV4ENGINE_H