path: root/src/scxml/qscxmlnulldatamodel.cpp

// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#include "qscxmlnulldatamodel.h"
#include "qscxmlevent.h"
#include "qscxmlstatemachine_p.h"
#include "qscxmltabledata.h"
#include "qscxmldatamodel_p.h"

QT_BEGIN_NAMESPACE

class QScxmlNullDataModelPrivate : public QScxmlDataModelPrivate
{
    Q_DECLARE_PUBLIC(QScxmlNullDataModel)

    struct ResolvedEvaluatorInfo {
        bool error;
        QString str;

        ResolvedEvaluatorInfo()
            : error(false)
        {}
    };

public:
    bool evalBool(QScxmlExecutableContent::EvaluatorId id, bool *ok)
    {
        Q_Q(QScxmlNullDataModel);
        Q_ASSERT(ok);

        ResolvedEvaluatorInfo info;
        Resolved::const_iterator it = resolved.find(id);
        if (it == resolved.end()) {
            info = prepare(id);
        } else {
            info = it.value();
        }

        if (info.error) {
            *ok = false;
            QScxmlStateMachinePrivate::get(q->stateMachine())->submitError(QStringLiteral("error.execution"), info.str);
            return false;
        }

        *ok = true;
        return q->stateMachine()->isActive(info.str);
    }

    ResolvedEvaluatorInfo prepare(QScxmlExecutableContent::EvaluatorId id)
    {
        auto td = m_stateMachine->tableData();
        const QScxmlExecutableContent::EvaluatorInfo &info = td->evaluatorInfo(id);
        QString expr = td->string(info.expr);
        for (int i = 0; i < expr.size(); ) {
            QChar ch = expr.at(i);
            if (ch.isSpace()) {
                expr.remove(i, 1);
            } else {
                ++i;
            }
        }

        ResolvedEvaluatorInfo resolved;
        if (expr.startsWith(QStringLiteral("In(")) && expr.endsWith(QLatin1Char(')'))) {
            resolved.error = false;
            resolved.str =  expr.mid(3, expr.size() - 4);
        } else {
            resolved.error = true;
            resolved.str =  QStringLiteral("%1 in %2").arg(expr, td->string(info.context));
        }
        return resolved;
    }

private:
    typedef QHash<QScxmlExecutableContent::EvaluatorId, ResolvedEvaluatorInfo> Resolved;
    Resolved resolved;
};

/*!
 * \class QScxmlNullDataModel
 * \brief The QScxmlNullDataModel class is the null data model for a Qt SCXML
 * stateMachine.
 * \since 5.7
 * \inmodule QtScxml
 *
 * This class implements the null data model as described in the
 * \l {SCXML Specification - B.1 The Null Data Model}. Using the value \c "null"
 * for the \e datamodel attribute of the \c <scxml> element means that there is
 * no underlying data model, but some executable content, like \c In(...) or
 * \c <log> can still be used.
 *
 * \sa QScxmlStateMachine QScxmlDataModel
 */

/*!
 * Creates a new Qt SCXML null data model, with the parent object \a parent.
 */
QScxmlNullDataModel::QScxmlNullDataModel(QObject *parent)
    : QScxmlDataModel(*(new QScxmlNullDataModelPrivate), parent)
{}

/*!
  Destroys the data model.
 */
QScxmlNullDataModel::~QScxmlNullDataModel()
{
}

/*!
  \reimp
 */
bool QScxmlNullDataModel::setup(const QVariantMap &initialDataValues)
{
    Q_UNUSED(initialDataValues);

    return true;
}

/*!
  \reimp
  Evaluates the executable content pointed to by \a id and records in \a ok
  whether there was an error. Returns the result of the evaluation as a string.
  The null data model can evaluate the \c <log> element, so this might result in
  an actual value, rather than an error
 */
QString QScxmlNullDataModel::evaluateToString(QScxmlExecutableContent::EvaluatorId id, bool *ok)
{
    Q_D(QScxmlNullDataModel);
    // We do implement this, because <log> is allowed in the Null data model,
    // and <log> has an expr attribute that needs "evaluation" for it to generate the log message.
    *ok = true;
    auto td = d->m_stateMachine->tableData();
    const QScxmlExecutableContent::EvaluatorInfo &info = td->evaluatorInfo(id);
    return td->string(info.expr);
}

/*!
  \reimp
  Evaluates the executable content pointed to by \a id and records in \a ok
  whether there was an error. Returns the result of the evaluation as a boolean
  value. The null data model can evaluate the instruction \c In(...), so this
  might result in an actual value, rather than an error.
 */
bool QScxmlNullDataModel::evaluateToBool(QScxmlExecutableContent::EvaluatorId id, bool *ok)
{
    Q_D(QScxmlNullDataModel);
    return d->evalBool(id, ok);
}

/*!
  \reimp
  Evaluates the executable content pointed to by \a id and records in \a ok
  whether there was an error. As this is the null data model, any evaluation will in
  fact result in an error, with \a ok set to \c false. Returns an empty QVariant.
 */
QVariant QScxmlNullDataModel::evaluateToVariant(QScxmlExecutableContent::EvaluatorId id, bool *ok)
{
    Q_UNUSED(id);
    *ok = false;
    QScxmlStateMachinePrivate::get(stateMachine())->submitError(
                QStringLiteral("error.execution"),
                QStringLiteral("Cannot evaluate expressions on a null data model"));
    return QVariant();
}

/*!
  \reimp
  Evaluates the executable content pointed to by \a id and records in \a ok
  whether there was an error. As this is the null data model, any evaluation will in
  fact result in an error, with \a ok set to \c false.
 */
void QScxmlNullDataModel::evaluateToVoid(QScxmlExecutableContent::EvaluatorId id, bool *ok)
{
    Q_UNUSED(id);
    *ok = false;
    QScxmlStateMachinePrivate::get(stateMachine())->submitError(
                QStringLiteral("error.execution"),
                QStringLiteral("Cannot evaluate expressions on a null data model"));
}

/*!
  \reimp
  Throws an error and sets \a ok to \c false, because the null data model cannot evaluate
  assignments.
 */
void QScxmlNullDataModel::evaluateAssignment(QScxmlExecutableContent::EvaluatorId id, bool *ok)
{
    Q_UNUSED(id);
    *ok = false;
    QScxmlStateMachinePrivate::get(stateMachine())->submitError(
                QStringLiteral("error.execution"),
                QStringLiteral("Cannot assign values on a null data model"));
}

/*!
  \reimp
  Throws an error and sets \a ok to \c false, because the null data model cannot
  initialize data.
 */
void QScxmlNullDataModel::evaluateInitialization(QScxmlExecutableContent::EvaluatorId id, bool *ok)
{
    Q_UNUSED(id);
    *ok = false;
    QScxmlStateMachinePrivate::get(stateMachine())->submitError(
                QStringLiteral("error.execution"),
                QStringLiteral("Cannot initialize values on a null data model"));
}

/*!
  \reimp
  Throws an error and sets \a ok to \c false, because the null data model cannot
  evaluate \c <foreach> blocks.
 */
void QScxmlNullDataModel::evaluateForeach(QScxmlExecutableContent::EvaluatorId id, bool *ok,
                                          ForeachLoopBody *body)
{
    Q_UNUSED(id);
    Q_UNUSED(body);
    *ok = false;
    QScxmlStateMachinePrivate::get(stateMachine())->submitError(
                QStringLiteral("error.execution"),
                QStringLiteral("Cannot run foreach on a null data model"));
}

/*!
 * \reimp
 * Does not actually set the \a event, because the null data model does not handle events.
 */
void QScxmlNullDataModel::setScxmlEvent(const QScxmlEvent &event)
{
    Q_UNUSED(event);
}

/*!
 * \reimp
 * Returns an invalid variant, because the null data model does not support
 * properties.
 */
QVariant QScxmlNullDataModel::scxmlProperty(const QString &name) const
{
    Q_UNUSED(name);
    return QVariant();
}

/*!
 * \reimp
 * Returns \c false, because the null data model does not support properties.
 */
bool QScxmlNullDataModel::hasScxmlProperty(const QString &name) const
{
    Q_UNUSED(name);
    return false;
}

/*!
 * \reimp
 * Returns \c false, because the null data model does not support properties.
 */
bool QScxmlNullDataModel::setScxmlProperty(const QString &name, const QVariant &value, const QString &context)
{
    Q_UNUSED(name);
    Q_UNUSED(value);
    Q_UNUSED(context);
    return false;
}

QT_END_NAMESPACE