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<td >Qt 5.12</td><td ><a href="qtscxml-index.html">Qt SCXML</a></td><td ><a href="qtscxml-module.html">C++ Classes</a></td><td >QScxmlCppDataModel</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right"><a href="qtscxml-index.html">Qt 5.12.6 Reference Documentation</a></td>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#reimplemented-public-functions">Reimplemented Public Functions</a></li>
<li class="level1"><a href="#static-public-members">Static Public Members</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">QScxmlCppDataModel Class</h1>
<!-- $$$QScxmlCppDataModel-brief -->
<p>The <a href="qscxmlcppdatamodel.html">QScxmlCppDataModel</a> class is a C++ data model for a Qt SCXML state machine. <a href="#details">More...</a></p>
<!-- @@@QScxmlCppDataModel -->
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> Header:</td><td class="memItemRight bottomAlign"> <span class="preprocessor">#include <QScxmlCppDataModel></span>
</td></tr><tr><td class="memItemLeft rightAlign topAlign"> qmake:</td><td class="memItemRight bottomAlign"> QT += scxml</td></tr><tr><td class="memItemLeft rightAlign topAlign"> Since:</td><td class="memItemRight bottomAlign"> Qt 5.7</td></tr><tr><td class="memItemLeft rightAlign topAlign"> Inherits:</td><td class="memItemRight bottomAlign"> <a href="qscxmldatamodel.html">QScxmlDataModel</a></td></tr></table></div><ul>
<li><a href="qscxmlcppdatamodel-members.html">List of all members, including inherited members</a></li>
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<a name="public-functions"></a>
<h2 id="public-functions">Public Functions</h2>
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#QScxmlCppDataModel">QScxmlCppDataModel</a></b>(QObject *<i>parent</i> = nullptr)</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#inState">inState</a></b>(const QString &<i>stateName</i>) const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const QScxmlEvent &</td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#scxmlEvent">scxmlEvent</a></b>() const</td></tr>
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<a name="reimplemented-public-functions"></a>
<h2 id="reimplemented-public-functions">Reimplemented Public Functions</h2>
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> virtual void </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#evaluateAssignment">evaluateAssignment</a></b>(QScxmlExecutableContent::EvaluatorId <i>id</i>, bool *<i>ok</i>) override</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual void </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#evaluateForeach">evaluateForeach</a></b>(QScxmlExecutableContent::EvaluatorId <i>id</i>, bool *<i>ok</i>, QScxmlDataModel::ForeachLoopBody *<i>body</i>) override</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual void </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#evaluateInitialization">evaluateInitialization</a></b>(QScxmlExecutableContent::EvaluatorId <i>id</i>, bool *<i>ok</i>) override</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual bool </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#hasScxmlProperty">hasScxmlProperty</a></b>(const QString &<i>name</i>) const override</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual QVariant </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#scxmlProperty">scxmlProperty</a></b>(const QString &<i>name</i>) const override</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual void </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#setScxmlEvent">setScxmlEvent</a></b>(const QScxmlEvent &<i>event</i>) override</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual bool </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#setScxmlProperty">setScxmlProperty</a></b>(const QString &<i>name</i>, const QVariant &<i>value</i>, const QString &<i>context</i>) override</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual bool </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#setup">setup</a></b>(const QVariantMap &<i>initialDataValues</i>) override</td></tr>
</table></div>
<ul>
<li class="fn">14 public functions inherited from <a href="qscxmldatamodel.html#public-functions">QScxmlDataModel</a></li>
</ul>
<a name="static-public-members"></a>
<h2 id="static-public-members">Static Public Members</h2>
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> const QMetaObject </td><td class="memItemRight bottomAlign"><b><a href="qscxmlcppdatamodel.html#staticMetaObject-var">staticMetaObject</a></b></td></tr>
</table></div>
<h3>Additional Inherited Members</h3>
<ul>
<li class="fn">1 property inherited from <a href="qscxmldatamodel.html#properties">QScxmlDataModel</a></li>
<li class="fn">1 signal inherited from <a href="qscxmldatamodel.html#signals">QScxmlDataModel</a></li>
</ul>
<a name="details"></a>
<!-- $$$QScxmlCppDataModel-description -->
<div class="descr">
<h2 id="details">Detailed Description</h2>
<p>The <a href="qscxmlcppdatamodel.html">QScxmlCppDataModel</a> class is a C++ data model for a Qt SCXML state machine.</p>
<p>The C++ data model for SCXML lets you write C++ code for <i>expr</i> attributes and <code><script></code> elements. The <i>data part</i> of the data model is backed by a subclass of <a href="qscxmlcppdatamodel.html">QScxmlCppDataModel</a>, for which the Qt SCXML compiler (<code>qscxmlc</code>) will generate the dispatch methods. It cannot be used when loading an SCXML file at runtime.</p>
<p>Usage is through the <i>datamodel</i> attribute of the <code><scxml></code> element:</p>
<pre class="cpp">
<span class="operator"><</span>scxml datamodel<span class="operator">=</span><span class="string">"cplusplus:TheDataModel:thedatamodel.h"</span> <span class="operator">.</span><span class="operator">.</span><span class="operator">.</span><span class="operator">.</span><span class="operator">></span>
</pre>
<p>The format of the <i>datamodel</i> attribute is: <code>cplusplus:<class-name>:<classdef-header></code>. So, for the example above, there should be a file <i>thedatamodel.h</i> containing a subclass of <a href="qscxmlcppdatamodel.html">QScxmlCppDataModel</a>, containing at least the following:</p>
<pre class="cpp">
<span class="preprocessor">#include "qscxmlcppdatamodel.h"</span>
<span class="keyword">class</span> TheDataModel: <span class="keyword">public</span> <span class="type"><a href="qscxmlcppdatamodel.html#QScxmlCppDataModel">QScxmlCppDataModel</a></span>
{
Q_OBJECT
Q_SCXML_DATAMODEL
};
</pre>
<p>The Q_SCXML_DATAMODEL has to appear in the private section of the class definition, for example right after the opening bracket, or after a Q_OBJECT macro. This macro expands to the declaration of some virtual methods whose implementation is generated by the Qt SCXML compiler.</p>
<p>The Qt SCXML compiler will generate the various <code>evaluateTo</code> methods, and convert expressions and scripts into lambdas inside those methods. For example:</p>
<pre class="cpp">
<span class="operator"><</span>scxml datamodel<span class="operator">=</span><span class="string">"cplusplus:TheDataModel:thedatamodel.h"</span> xmlns<span class="operator">=</span><span class="string">"http://www.w3.org/2005/07/scxml"</span> version<span class="operator">=</span><span class="string">"1.0"</span> name<span class="operator">=</span><span class="string">"MediaPlayerStateMachine"</span><span class="operator">></span>
<span class="operator"><</span>state id<span class="operator">=</span><span class="string">"stopped"</span><span class="operator">></span>
<span class="operator"><</span>transition event<span class="operator">=</span><span class="string">"tap"</span> <span class="type">cond</span><span class="operator">=</span><span class="string">"isValidMedia()"</span> target<span class="operator">=</span><span class="string">"playing"</span><span class="operator">/</span><span class="operator">></span>
<span class="operator"><</span><span class="operator">/</span>state<span class="operator">></span>
<span class="operator"><</span>state id<span class="operator">=</span><span class="string">"playing"</span><span class="operator">></span>
<span class="operator"><</span>onentry<span class="operator">></span>
<span class="operator"><</span>script<span class="operator">></span>
media <span class="operator">=</span> eventData()<span class="operator">.</span>value(<span class="type">QStringLiteral</span>(<span class="operator">&</span>quot;media<span class="operator">&</span>quot;))<span class="operator">.</span>toString();
<span class="operator"><</span><span class="operator">/</span>script<span class="operator">></span>
<span class="operator"><</span>send event<span class="operator">=</span><span class="string">"playbackStarted"</span><span class="operator">></span>
<span class="operator"><</span>param name<span class="operator">=</span><span class="string">"media"</span> expr<span class="operator">=</span><span class="string">"media"</span><span class="operator">/</span><span class="operator">></span>
<span class="operator"><</span><span class="operator">/</span>send<span class="operator">></span>
<span class="operator"><</span><span class="operator">/</span>onentry<span class="operator">></span>
<span class="operator"><</span><span class="operator">/</span>state<span class="operator">></span>
<span class="operator"><</span><span class="operator">/</span>scxml<span class="operator">></span>
</pre>
<p>This will result in:</p>
<pre class="cpp">
bool TheDataModel<span class="operator">::</span>evaluateToBool(<span class="type">QScxmlExecutableContent</span><span class="operator">::</span>EvaluatorId id<span class="operator">,</span> bool <span class="operator">*</span>ok) {
<span class="comment">// ....</span>
<span class="keyword">return</span> <span class="operator">[</span><span class="keyword">this</span><span class="operator">]</span>()<span class="operator">-</span><span class="operator">></span>bool{ <span class="keyword">return</span> isValidMedia(); }();
<span class="comment">// ....</span>
}
<span class="type">QVariant</span> TheDataModel<span class="operator">::</span>evaluateToVariant(<span class="type">QScxmlExecutableContent</span><span class="operator">::</span>EvaluatorId id<span class="operator">,</span> bool <span class="operator">*</span>ok) {
<span class="comment">// ....</span>
<span class="keyword">return</span> <span class="operator">[</span><span class="keyword">this</span><span class="operator">]</span>()<span class="operator">-</span><span class="operator">></span><span class="type">QVariant</span>{ <span class="keyword">return</span> media; }();
<span class="comment">// ....</span>
}
<span class="type">void</span> TheDataModel<span class="operator">::</span>evaluateToVoid(<span class="type">QScxmlExecutableContent</span><span class="operator">::</span>EvaluatorId id<span class="operator">,</span> bool <span class="operator">*</span>ok) {
<span class="comment">// ....</span>
<span class="operator">[</span><span class="keyword">this</span><span class="operator">]</span>()<span class="operator">-</span><span class="operator">></span><span class="type">void</span>{ media <span class="operator">=</span> eventData()<span class="operator">.</span>value(<span class="type">QStringLiteral</span>(<span class="string">"media"</span>))<span class="operator">.</span>toString(); }();
<span class="comment">// ....</span>
}
</pre>
<p>So, you are not limited to call functions. In a <code><script></code> element you can put zero or more C++ statements, and in <i>cond</i> or <i>expr</i> attributes you can use any C++ expression that can be converted to the respective bool or QVariant. And, as the <code>this</code> pointer is also captured, you can call or access the data model (the <i>media</i> attribute in the example above). For the full example, see <a href="qtscxml-mediaplayer-qml-cppdatamodel-example.html">Qt SCXML: Media Player QML Example (C++ Data Model)</a>.</p>
</div>
<p><b>See also </b><a href="qscxmlstatemachine.html">QScxmlStateMachine</a> and <a href="qscxmldatamodel.html">QScxmlDataModel</a>.</p>
<!-- @@@QScxmlCppDataModel -->
<div class="func">
<h2>Member Function Documentation</h2>
<!-- $$$QScxmlCppDataModel[overload1]$$$QScxmlCppDataModelQObject* -->
<h3 class="fn" id="QScxmlCppDataModel"><a name="QScxmlCppDataModel"></a>QScxmlCppDataModel::<span class="name">QScxmlCppDataModel</span>(<span class="type">QObject</span> *<i>parent</i> = nullptr)</h3>
<p>Creates a new C++ data model with the parent object <i>parent</i>.</p>
<!-- @@@QScxmlCppDataModel -->
<!-- $$$evaluateAssignment[overload1]$$$evaluateAssignmentQScxmlExecutableContent::EvaluatorIdbool* -->
<h3 class="fn" id="evaluateAssignment"><a name="evaluateAssignment"></a><code>[override virtual] </code><span class="type">void</span> QScxmlCppDataModel::<span class="name">evaluateAssignment</span>(<span class="type"><a href="qscxmlexecutablecontent.html#EvaluatorId-typedef">QScxmlExecutableContent::EvaluatorId</a></span> <i>id</i>, <span class="type">bool</span> *<i>ok</i>)</h3>
<p>Reimplemented from <a href="qscxmldatamodel.html#evaluateAssignment">QScxmlDataModel::evaluateAssignment</a>().</p>
<p>This method does not perform any action, ignores <i>id</i>, and sets <i>ok</i> to <code>false</code>. Override it in your specific data model in order to implement <code><assign></code>.</p>
<!-- @@@evaluateAssignment -->
<!-- $$$evaluateForeach[overload1]$$$evaluateForeachQScxmlExecutableContent::EvaluatorIdbool*QScxmlDataModel::ForeachLoopBody* -->
<h3 class="fn" id="evaluateForeach"><a name="evaluateForeach"></a><code>[override virtual] </code><span class="type">void</span> QScxmlCppDataModel::<span class="name">evaluateForeach</span>(<span class="type"><a href="qscxmlexecutablecontent.html#EvaluatorId-typedef">QScxmlExecutableContent::EvaluatorId</a></span> <i>id</i>, <span class="type">bool</span> *<i>ok</i>, <span class="type"><a href="qscxmldatamodel-foreachloopbody.html">QScxmlDataModel::ForeachLoopBody</a></span> *<i>body</i>)</h3>
<p>Reimplemented from <a href="qscxmldatamodel.html#evaluateForeach">QScxmlDataModel::evaluateForeach</a>().</p>
<p>This method does not perform any action, ignores <i>id</i> and <i>body</i>, and sets <i>ok</i> to <code>false</code>. Override it in your specific data model in order to implement <code><foreach></code>.</p>
<!-- @@@evaluateForeach -->
<!-- $$$evaluateInitialization[overload1]$$$evaluateInitializationQScxmlExecutableContent::EvaluatorIdbool* -->
<h3 class="fn" id="evaluateInitialization"><a name="evaluateInitialization"></a><code>[override virtual] </code><span class="type">void</span> QScxmlCppDataModel::<span class="name">evaluateInitialization</span>(<span class="type"><a href="qscxmlexecutablecontent.html#EvaluatorId-typedef">QScxmlExecutableContent::EvaluatorId</a></span> <i>id</i>, <span class="type">bool</span> *<i>ok</i>)</h3>
<p>Reimplemented from <a href="qscxmldatamodel.html#evaluateInitialization">QScxmlDataModel::evaluateInitialization</a>().</p>
<p>This method does not perform any action, ignores <i>id</i>, and sets <i>ok</i> to <code>false</code>. Override it in your specific data model in order to implement <code><data></code>.</p>
<!-- @@@evaluateInitialization -->
<!-- $$$hasScxmlProperty[overload1]$$$hasScxmlPropertyconstQString& -->
<h3 class="fn" id="hasScxmlProperty"><a name="hasScxmlProperty"></a><code>[override virtual] </code><span class="type">bool</span> QScxmlCppDataModel::<span class="name">hasScxmlProperty</span>(const <span class="type">QString</span> &<i>name</i>) const</h3>
<p>Reimplemented from <a href="qscxmldatamodel.html#hasScxmlProperty">QScxmlDataModel::hasScxmlProperty</a>().</p>
<p>This method always returns <code>false</code> and ignores <i>name</i>. Override it to implement the lookup of data model properties via the <code>location</code> attribute of various elements.</p>
<!-- @@@hasScxmlProperty -->
<!-- $$$inState[overload1]$$$inStateconstQString& -->
<h3 class="fn" id="inState"><a name="inState"></a><span class="type">bool</span> QScxmlCppDataModel::<span class="name">inState</span>(const <span class="type">QString</span> &<i>stateName</i>) const</h3>
<p>Returns <code>true</code> if the state machine is in the state specified by <i>stateName</i>, <code>false</code> otherwise.</p>
<!-- @@@inState -->
<!-- $$$scxmlEvent[overload1]$$$scxmlEvent -->
<h3 class="fn" id="scxmlEvent"><a name="scxmlEvent"></a>const <span class="type"><a href="qscxmlevent.html">QScxmlEvent</a></span> &QScxmlCppDataModel::<span class="name">scxmlEvent</span>() const</h3>
<p>Holds the current event that is being processed by the state machine.</p>
<p>See also <a href="https://www.w3.org/TR/scxml/#SystemVariables">SCXML Specification - 5.10 System Variables</a> for the description of the <code>_event</code> variable.</p>
<p>Returns the event currently being processed.</p>
<p><b>See also </b><a href="qscxmlcppdatamodel.html#setScxmlEvent">setScxmlEvent</a>().</p>
<!-- @@@scxmlEvent -->
<!-- $$$scxmlProperty[overload1]$$$scxmlPropertyconstQString& -->
<h3 class="fn" id="scxmlProperty"><a name="scxmlProperty"></a><code>[override virtual] </code><span class="type">QVariant</span> QScxmlCppDataModel::<span class="name">scxmlProperty</span>(const <span class="type">QString</span> &<i>name</i>) const</h3>
<p>Reimplemented from <a href="qscxmldatamodel.html#scxmlProperty">QScxmlDataModel::scxmlProperty</a>().</p>
<p>This method always returns an empty QVariant and ignores <i>name</i>. Override it to implement the lookup of data model properties via the <code>location</code> attribute of various elements.</p>
<p><b>See also </b><a href="qscxmlcppdatamodel.html#setScxmlProperty">setScxmlProperty</a>().</p>
<!-- @@@scxmlProperty -->
<!-- $$$setScxmlEvent[overload1]$$$setScxmlEventconstQScxmlEvent& -->
<h3 class="fn" id="setScxmlEvent"><a name="setScxmlEvent"></a><code>[override virtual] </code><span class="type">void</span> QScxmlCppDataModel::<span class="name">setScxmlEvent</span>(const <span class="type"><a href="qscxmlevent.html">QScxmlEvent</a></span> &<i>event</i>)</h3>
<p>Reimplemented from <a href="qscxmldatamodel.html#setScxmlEvent">QScxmlDataModel::setScxmlEvent</a>().</p>
<p>Sets the <i>event</i> that will be processed next.</p>
<p><b>See also </b><a href="qscxmlcppdatamodel.html#scxmlEvent">QScxmlCppDataModel::scxmlEvent</a>.</p>
<!-- @@@setScxmlEvent -->
<!-- $$$setScxmlProperty[overload1]$$$setScxmlPropertyconstQString&constQVariant&constQString& -->
<h3 class="fn" id="setScxmlProperty"><a name="setScxmlProperty"></a><code>[override virtual] </code><span class="type">bool</span> QScxmlCppDataModel::<span class="name">setScxmlProperty</span>(const <span class="type">QString</span> &<i>name</i>, const <span class="type">QVariant</span> &<i>value</i>, const <span class="type">QString</span> &<i>context</i>)</h3>
<p>Reimplemented from <a href="qscxmldatamodel.html#setScxmlProperty">QScxmlDataModel::setScxmlProperty</a>().</p>
<p>This method always returns <code>false</code> and ignores <i>name</i>, <i>value</i>, and <i>context</i>. Override it to implement the lookup of data model properties via the <code>location</code> attribute of various elements.</p>
<p><b>See also </b><a href="qscxmlcppdatamodel.html#scxmlProperty">scxmlProperty</a>().</p>
<!-- @@@setScxmlProperty -->
<!-- $$$setup[overload1]$$$setupconstQVariantMap& -->
<h3 class="fn" id="setup"><a name="setup"></a><code>[override virtual] </code><span class="type">bool</span> QScxmlCppDataModel::<span class="name">setup</span>(const <span class="type">QVariantMap</span> &<i>initialDataValues</i>)</h3>
<p>Reimplemented from <a href="qscxmldatamodel.html#setup">QScxmlDataModel::setup</a>().</p>
<p>Called during state machine initialization to set up a state machine using the initial values for data model variables specified by their keys, <i>initialDataValues</i>. These are the values specified by <code><param></code> tags in an <code><invoke></code> element.</p>
<p><b>Note: </b>This function can be invoked via the meta-object system and from QML. See Q_INVOKABLE.</p>
<p><b>See also </b><a href="qscxmlstatemachine.html#init">QScxmlStateMachine::init</a>.</p>
<!-- @@@setup -->
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