diff options
Diffstat (limited to 'src/script/api/qscriptcontext.cpp')
| -rw-r--r-- | src/script/api/qscriptcontext.cpp | 764 |
1 files changed, 764 insertions, 0 deletions
diff --git a/src/script/api/qscriptcontext.cpp b/src/script/api/qscriptcontext.cpp new file mode 100644 index 000000000..0b1ca33f4 --- /dev/null +++ b/src/script/api/qscriptcontext.cpp @@ -0,0 +1,764 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the QtScript module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain +** additional rights. These rights are described in the Nokia Qt LGPL +** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at http://qt.nokia.com/contact. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "config.h" +#include "qscriptcontext.h" + +#include "qscriptcontext_p.h" +#include "qscriptcontextinfo.h" +#include "qscriptengine.h" +#include "qscriptengine_p.h" +#include "../bridge/qscriptactivationobject_p.h" + +#include "Arguments.h" +#include "CodeBlock.h" +#include "Error.h" +#include "JSFunction.h" +#include "JSObject.h" +#include "JSGlobalObject.h" + +#include <QtCore/qstringlist.h> + +QT_BEGIN_NAMESPACE + +/*! + \since 4.3 + \class QScriptContext + + \brief The QScriptContext class represents a Qt Script function invocation. + + \ingroup script + \mainclass + + A QScriptContext provides access to the `this' object and arguments + passed to a script function. You typically want to access this + information when you're writing a native (C++) function (see + QScriptEngine::newFunction()) that will be called from script + code. For example, when the script code + + \snippet doc/src/snippets/code/src_script_qscriptcontext.cpp 0 + + is evaluated, a QScriptContext will be created, and the context will + carry the arguments as QScriptValues; in this particular case, the + arguments will be one QScriptValue containing the number 20.5, a second + QScriptValue containing the string \c{"hello"}, and a third QScriptValue + containing a Qt Script object. + + Use argumentCount() to get the number of arguments passed to the + function, and argument() to get an argument at a certain index. The + argumentsObject() function returns a Qt Script array object + containing all the arguments; you can use the QScriptValueIterator + to iterate over its elements, or pass the array on as arguments to + another script function using QScriptValue::call(). + + Use thisObject() to get the `this' object associated with the function call, + and setThisObject() to set the `this' object. If you are implementing a + native "instance method", you typically fetch the thisObject() and access + one or more of its properties: + + \snippet doc/src/snippets/code/src_script_qscriptcontext.cpp 1 + + Use isCalledAsConstructor() to determine if the function was called + as a constructor (e.g. \c{"new foo()"} (as constructor) or just + \c{"foo()"}). When a function is called as a constructor, the + thisObject() contains the newly constructed object that the function + is expected to initialize. + + Use throwValue() or throwError() to throw an exception. + + Use callee() to obtain the QScriptValue that represents the function being + called. This can for example be used to call the function recursively. + + Use parentContext() to get a pointer to the context that precedes + this context in the activation stack. This is mostly useful for + debugging purposes (e.g. when constructing some form of backtrace). + + The activationObject() function returns the object that is used to + hold the local variables associated with this function call. You can + replace the activation object by calling setActivationObject(). A + typical usage of these functions is when you want script code to be + evaluated in the context of the parent context, e.g. to implement an + include() function: + + \snippet doc/src/snippets/code/src_script_qscriptcontext.cpp 2 + + Use backtrace() to get a human-readable backtrace associated with + this context. This can be useful for debugging purposes when + implementing native functions. The toString() function provides a + string representation of the context. (QScriptContextInfo provides + more detailed debugging-related information about the + QScriptContext.) + + Use engine() to obtain a pointer to the QScriptEngine that this context + resides in. + + \sa QScriptContextInfo, QScriptEngine::newFunction(), QScriptable +*/ + +/*! + \enum QScriptContext::ExecutionState + + This enum specifies the frameution state of the context. + + \value NormalState The context is in a normal state. + + \value ExceptionState The context is in an exceptional state. +*/ + +/*! + \enum QScriptContext::Error + + This enum specifies types of error. + + \value ReferenceError A reference error. + + \value SyntaxError A syntax error. + + \value TypeError A type error. + + \value RangeError A range error. + + \value URIError A URI error. + + \value UnknownError An unknown error. +*/ + +/*! + \internal +*/ +QScriptContext::QScriptContext() +{ + //QScriptContext doesn't exist, pointer to QScriptContext are just pointer to JSC::CallFrame + Q_ASSERT(false); +} + +/*! + Throws an exception with the given \a value. + Returns the value thrown (the same as the argument). + + \sa throwError(), state() +*/ +QScriptValue QScriptContext::throwValue(const QScriptValue &value) +{ + JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + JSC::JSValue jscValue = QScript::scriptEngineFromExec(frame)->scriptValueToJSCValue(value); + frame->setException(jscValue); + return value; +} + +/*! + Throws an \a error with the given \a text. + Returns the created error object. + + The \a text will be stored in the \c{message} property of the error + object. + + The error object will be initialized to contain information about + the location where the error occurred; specifically, it will have + properties \c{lineNumber}, \c{fileName} and \c{stack}. These + properties are described in \l {QtScript Extensions to ECMAScript}. + + \sa throwValue(), state() +*/ +QScriptValue QScriptContext::throwError(Error error, const QString &text) +{ + JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + JSC::ErrorType jscError = JSC::GeneralError; + switch (error) { + case UnknownError: + break; + case ReferenceError: + jscError = JSC::ReferenceError; + break; + case SyntaxError: + jscError = JSC::SyntaxError; + break; + case TypeError: + jscError = JSC::TypeError; + break; + case RangeError: + jscError = JSC::RangeError; + break; + case URIError: + jscError = JSC::URIError; + break; + } + JSC::JSObject *result = JSC::throwError(frame, jscError, text); + return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(result); +} + +/*! + \overload + + Throws an error with the given \a text. + Returns the created error object. + + \sa throwValue(), state() +*/ +QScriptValue QScriptContext::throwError(const QString &text) +{ + JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + JSC::JSObject *result = JSC::throwError(frame, JSC::GeneralError, text); + return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(result); +} + +/*! + Destroys this QScriptContext. +*/ +QScriptContext::~QScriptContext() +{ + //QScriptContext doesn't exist, pointer to QScriptContext are just pointer to JSC::CallFrame + Q_ASSERT(false); +} + +/*! + Returns the QScriptEngine that this QScriptContext belongs to. +*/ +QScriptEngine *QScriptContext::engine() const +{ + const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + return QScriptEnginePrivate::get(QScript::scriptEngineFromExec(frame)); +} + +/*! + Returns the function argument at the given \a index. + + If \a index >= argumentCount(), a QScriptValue of + the primitive type Undefined is returned. + + \sa argumentCount() +*/ +QScriptValue QScriptContext::argument(int index) const +{ + if (index < 0) + return QScriptValue(); + if (index >= argumentCount()) + return QScriptValue(QScriptValue::UndefinedValue); + QScriptValue v = argumentsObject().property(index); + return v; +} + +/*! + Returns the callee. The callee is the function object that this + QScriptContext represents an invocation of. +*/ +QScriptValue QScriptContext::callee() const +{ + const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(frame->callee()); +} + +/*! + Returns the arguments object of this QScriptContext. + + The arguments object has properties \c callee (equal to callee()) + and \c length (equal to argumentCount()), and properties \c 0, \c 1, + ..., argumentCount() - 1 that provide access to the argument + values. Initially, property \c P (0 <= \c P < argumentCount()) has + the same value as argument(\c P). In the case when \c P is less + than the number of formal parameters of the function, \c P shares + its value with the corresponding property of the activation object + (activationObject()). This means that changing this property changes + the corresponding property of the activation object and vice versa. + + \sa argument(), activationObject() +*/ +QScriptValue QScriptContext::argumentsObject() const +{ + JSC::CallFrame *frame = const_cast<JSC::ExecState*>(QScriptEnginePrivate::frameForContext(this)); + + if (frame == frame->lexicalGlobalObject()->globalExec() || frame->callerFrame()->hasHostCallFrameFlag()) { + // <global> or <eval> context doesn't have arguments. return an empty object + return QScriptEnginePrivate::get(QScript::scriptEngineFromExec(frame))->newObject(); + } + + //for a js function + if (frame->codeBlock() && frame->callee()) { + JSC::JSValue result = frame->interpreter()->retrieveArguments(frame, JSC::asFunction(frame->callee())); + return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(result); + } + + //for a native function + if (!frame->optionalCalleeArguments()) { + Q_ASSERT(frame->argumentCount() > 0); //we need at least 'this' otherwise we'll crash later + JSC::Arguments* arguments = new (&frame->globalData())JSC::Arguments(frame, JSC::Arguments::NoParameters); + frame->setCalleeArguments(arguments); + } + return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(frame->optionalCalleeArguments()); +} + +/*! + Returns true if the function was called as a constructor + (e.g. \c{"new foo()"}); otherwise returns false. + + When a function is called as constructor, the thisObject() + contains the newly constructed object to be initialized. +*/ +bool QScriptContext::isCalledAsConstructor() const +{ + JSC::CallFrame *frame = const_cast<JSC::ExecState*>(QScriptEnginePrivate::frameForContext(this)); + + //For native functions, look up flags. + uint flags = QScriptEnginePrivate::contextFlags(frame); + if (flags & QScriptEnginePrivate::NativeContext) + return flags & QScriptEnginePrivate::CalledAsConstructorContext; + + //Not a native function, try to look up in the bytecode if we where called from op_construct + JSC::Instruction* returnPC = frame->returnPC(); + + if (!returnPC) + return false; + + JSC::CallFrame *callerFrame = QScriptEnginePrivate::frameForContext(parentContext()); + if (!callerFrame) + return false; + + if (returnPC[-JSC::op_construct_length].u.opcode == frame->interpreter()->getOpcode(JSC::op_construct)) { + //We are maybe called from the op_construct opcode which has 6 opperands. + //But we need to check we are not called from op_call with 4 opperands + + //we make sure that the returnPC[-1] (thisRegister) is smaller than the returnPC[-3] (registerOffset) + //as if it was an op_call, the returnPC[-1] would be the registerOffset, bigger than returnPC[-3] (funcRegister) + return returnPC[-1].u.operand < returnPC[-3].u.operand; + } + return false; +} + +/*! + Returns the parent context of this QScriptContext. +*/ +QScriptContext *QScriptContext::parentContext() const +{ + const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + JSC::CallFrame *callerFrame = frame->callerFrame()->removeHostCallFrameFlag(); + if (callerFrame && callerFrame->callerFrame()->hasHostCallFrameFlag() + && callerFrame->callerFrame()->removeHostCallFrameFlag() == QScript::scriptEngineFromExec(frame)->globalExec()) { + //skip the "fake" context created in Interpreter::execute. + callerFrame = callerFrame->callerFrame()->removeHostCallFrameFlag(); + } + return reinterpret_cast<QScriptContext *>(callerFrame); +} + +/*! + Returns the number of arguments passed to the function + in this invocation. + + Note that the argument count can be different from the + formal number of arguments (the \c{length} property of + callee()). + + \sa argument() +*/ +int QScriptContext::argumentCount() const +{ + const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + int argc = frame->argumentCount(); + if (argc != 0) + --argc; // -1 due to "this" + return argc; +} + +/*! + \internal +*/ +QScriptValue QScriptContext::returnValue() const +{ + qWarning("QScriptContext::returnValue() not implemented"); + return QScriptValue(); +} + +/*! + \internal +*/ +void QScriptContext::setReturnValue(const QScriptValue &result) +{ + JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + JSC::CallFrame *callerFrame = frame->callerFrame(); + if (!callerFrame->codeBlock()) + return; + Q_ASSERT_X(false, Q_FUNC_INFO, "check me"); + int dst = frame->registers()[JSC::RegisterFile::ReturnValueRegister].i(); // returnValueRegister() is private + callerFrame[dst] = QScript::scriptEngineFromExec(frame)->scriptValueToJSCValue(result); +} + +/*! + Returns the activation object of this QScriptContext. The activation + object provides access to the local variables associated with this + context. + + \sa argument(), argumentsObject() +*/ + +QScriptValue QScriptContext::activationObject() const +{ + JSC::CallFrame *frame = const_cast<JSC::ExecState*>(QScriptEnginePrivate::frameForContext(this)); + JSC::JSObject *result = 0; + + uint flags = QScriptEnginePrivate::contextFlags(frame); + if ((flags & QScriptEnginePrivate::NativeContext) && !(flags & QScriptEnginePrivate::HasScopeContext)) { + //For native functions, lazily create it if needed + QScript::QScriptActivationObject *scope = new (frame) QScript::QScriptActivationObject(frame); + frame->setScopeChain(frame->scopeChain()->copy()->push(scope)); + result = scope; + QScriptEnginePrivate::setContextFlags(frame, flags | QScriptEnginePrivate::HasScopeContext); + } else { + // look in scope chain + JSC::ScopeChainNode *node = frame->scopeChain(); + JSC::ScopeChainIterator it(node); + for (it = node->begin(); it != node->end(); ++it) { + if ((*it) && (*it)->isVariableObject()) { + result = *it; + break; + } + } + } + if (!result) { + if (!parentContext()) + return engine()->globalObject(); + + qWarning("QScriptContext::activationObject: could not get activation object for frame"); + return QScriptValue(); + /*JSC::CodeBlock *codeBlock = frame->codeBlock(); + if (!codeBlock) { + // non-Qt native function + Q_ASSERT(true); //### this should in theorry not happen + result = new (frame)QScript::QScriptActivationObject(frame); + } else { + // ### this is wrong + JSC::FunctionBodyNode *body = static_cast<JSC::FunctionBodyNode*>(codeBlock->ownerNode()); + result = new (frame)JSC::JSActivation(frame, body); + }*/ + } + + if (result && result->isObject(&QScript::QScriptActivationObject::info) + && (static_cast<QScript::QScriptActivationObject*>(result)->delegate() != 0)) { + // Return the object that property access is being delegated to + result = static_cast<QScript::QScriptActivationObject*>(result)->delegate(); + } + + return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(result); +} + +/*! + Sets the activation object of this QScriptContext to be the given \a + activation. + + If \a activation is not an object, this function does nothing. +*/ +void QScriptContext::setActivationObject(const QScriptValue &activation) +{ + if (!activation.isObject()) + return; + else if (activation.engine() != engine()) { + qWarning("QScriptContext::setActivationObject() failed: " + "cannot set an object created in " + "a different engine"); + return; + } + JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame); + JSC::JSObject *object = JSC::asObject(engine->scriptValueToJSCValue(activation)); + if (object == engine->originalGlobalObjectProxy) + object = engine->originalGlobalObject(); + + uint flags = QScriptEnginePrivate::contextFlags(frame); + if ((flags & QScriptEnginePrivate::NativeContext) && !(flags & QScriptEnginePrivate::HasScopeContext)) { + //For native functions, we create a scope node + JSC::JSObject *scope = object; + if (!scope->isVariableObject()) { + // Create a QScriptActivationObject that acts as a proxy + scope = new (frame) QScript::QScriptActivationObject(frame, scope); + } + frame->setScopeChain(frame->scopeChain()->copy()->push(scope)); + QScriptEnginePrivate::setContextFlags(frame, flags | QScriptEnginePrivate::HasScopeContext); + return; + } + + // else replace the first activation object in the scope chain + JSC::ScopeChainNode *node = frame->scopeChain(); + while (node != 0) { + if (node->object && node->object->isVariableObject()) { + if (!object->isVariableObject()) { + if (node->object->isObject(&QScript::QScriptActivationObject::info)) { + static_cast<QScript::QScriptActivationObject*>(node->object)->setDelegate(object); + } else { + // Create a QScriptActivationObject that acts as a proxy + node->object = new (frame) QScript::QScriptActivationObject(frame, object); + } + } else { + node->object = object; + } + break; + } + node = node->next; + } +} + +/*! + Returns the `this' object associated with this QScriptContext. +*/ +QScriptValue QScriptContext::thisObject() const +{ + JSC::CallFrame *frame = const_cast<JSC::ExecState*>(QScriptEnginePrivate::frameForContext(this)); + QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame); + JSC::JSValue result = engine->thisForContext(frame); + if (!result || result.isNull()) + result = frame->globalThisValue(); + return engine->scriptValueFromJSCValue(result); +} + +/*! + Sets the `this' object associated with this QScriptContext to be + \a thisObject. + + If \a thisObject is not an object, this function does nothing. +*/ +void QScriptContext::setThisObject(const QScriptValue &thisObject) +{ + JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + if (!thisObject.isObject()) + return; + if (thisObject.engine() != engine()) { + qWarning("QScriptContext::setThisObject() failed: " + "cannot set an object created in " + "a different engine"); + return; + } + if (frame == frame->lexicalGlobalObject()->globalExec()) { + engine()->setGlobalObject(thisObject); + return; + } + JSC::JSValue jscThisObject = QScript::scriptEngineFromExec(frame)->scriptValueToJSCValue(thisObject); + JSC::CodeBlock *cb = frame->codeBlock(); + if (cb != 0) { + frame[cb->thisRegister()] = jscThisObject; + } else { + JSC::Register* thisRegister = frame->registers() - JSC::RegisterFile::CallFrameHeaderSize - frame->argumentCount(); + thisRegister[0] = jscThisObject; + } +} + +/*! + Returns the frameution state of this QScriptContext. +*/ +QScriptContext::ExecutionState QScriptContext::state() const +{ + const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + if (frame->hadException()) + return QScriptContext::ExceptionState; + return QScriptContext::NormalState; +} + +/*! + Returns a human-readable backtrace of this QScriptContext. + + Each line is of the form \c{<function-name>(<arguments>)@<file-name>:<line-number>}. + + To access individual pieces of debugging-related information (for + example, to construct your own backtrace representation), use + QScriptContextInfo. + + \sa QScriptEngine::uncaughtExceptionBacktrace(), QScriptContextInfo, toString() +*/ +QStringList QScriptContext::backtrace() const +{ + QStringList result; + const QScriptContext *ctx = this; + while (ctx) { + result.append(ctx->toString()); + ctx = ctx->parentContext(); + } + return result; +} + +/*! + \since 4.4 + + Returns a string representation of this context. + This is useful for debugging. + + \sa backtrace() +*/ +QString QScriptContext::toString() const +{ + QScriptContextInfo info(this); + QString result; + + QString functionName = info.functionName(); + if (functionName.isEmpty()) { + if (parentContext()) { + const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + if (info.functionType() == QScriptContextInfo::ScriptFunction) + result.append(QLatin1String("<anonymous>")); + else if(frame->callerFrame()->hasHostCallFrameFlag()) + result.append(QLatin1String("<eval>")); + else + result.append(QLatin1String("<native>")); + } else { + result.append(QLatin1String("<global>")); + } + } else { + result.append(functionName); + } + + QStringList parameterNames = info.functionParameterNames(); + result.append(QLatin1Char('(')); + for (int i = 0; i < argumentCount(); ++i) { + if (i > 0) + result.append(QLatin1String(", ")); + if (i < parameterNames.count()) { + result.append(parameterNames.at(i)); + result.append(QLatin1String(" = ")); + } + QScriptValue arg = argument(i); + if (arg.isString()) + result.append(QLatin1Char('\'')); + result.append(arg.toString()); + if (arg.isString()) + result.append(QLatin1Char('\'')); + + } + result.append(QLatin1Char(')')); + + QString fileName = info.fileName(); + int lineNumber = info.lineNumber(); + result.append(QLatin1String(" at ")); + if (!fileName.isEmpty()) { + result.append(fileName); + result.append(QLatin1Char(':')); + } + result.append(QString::number(lineNumber)); + return result; +} + +/*! + \internal + \since 4.5 + + Returns the scope chain of this QScriptContext. +*/ +QScriptValueList QScriptContext::scopeChain() const +{ + activationObject(); //ensure the creation of the normal scope for native context + const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame); + QScriptValueList result; + JSC::ScopeChainNode *node = frame->scopeChain(); + JSC::ScopeChainIterator it(node); + for (it = node->begin(); it != node->end(); ++it) { + JSC::JSObject *object = *it; + if (!object) + continue; + if (object->isObject(&QScript::QScriptActivationObject::info) + && (static_cast<QScript::QScriptActivationObject*>(object)->delegate() != 0)) { + // Return the object that property access is being delegated to + object = static_cast<QScript::QScriptActivationObject*>(object)->delegate(); + } + result.append(engine->scriptValueFromJSCValue(object)); + } + return result; +} + +/*! + \internal + \since 4.5 + + Adds the given \a object to the front of this context's scope chain. + + If \a object is not an object, this function does nothing. +*/ +void QScriptContext::pushScope(const QScriptValue &object) +{ + activationObject(); //ensure the creation of the normal scope for native context + if (!object.isObject()) + return; + else if (object.engine() != engine()) { + qWarning("QScriptContext::pushScope() failed: " + "cannot push an object created in " + "a different engine"); + return; + } + JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame); + JSC::JSObject *jscObject = JSC::asObject(engine->scriptValueToJSCValue(object)); + if (jscObject == engine->originalGlobalObjectProxy) + jscObject = engine->originalGlobalObject(); + JSC::ScopeChainNode *scope = frame->scopeChain(); + Q_ASSERT(scope != 0); + if (!scope->object) { + // pushing to an "empty" chain + if (!jscObject->isGlobalObject()) { + qWarning("QScriptContext::pushScope() failed: initial object in scope chain has to be the Global Object"); + return; + } + scope->object = jscObject; + } + else + frame->setScopeChain(scope->push(jscObject)); +} + +/*! + \internal + \since 4.5 + + Removes the front object from this context's scope chain, and + returns the removed object. + + If the scope chain is already empty, this function returns an + invalid QScriptValue. +*/ +QScriptValue QScriptContext::popScope() +{ + JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this); + JSC::ScopeChainNode *scope = frame->scopeChain(); + Q_ASSERT(scope != 0); + QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame); + QScriptValue result = engine->scriptValueFromJSCValue(scope->object); + if (!scope->next) { + // We cannot have a null scope chain, so just zap the object pointer. + scope->object = 0; + } else { + frame->setScopeChain(scope->pop()); + } + return result; +} + +QT_END_NAMESPACE |