help/info/alt.html

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  13 <title>alt</title>
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  32 <h1>alt</h1>
  33 <hr align="left" width="75%">
  34 <p>The statement denotes branching of test behavior due to the reception and handling of communication and/or timer events and/or the termination of parallel test components. The individual
  35 alternatives (or branches) begin with a Boolean guard enabling or disabling the alternative (default is true), continue with an event or â€œreceiving operationâ€�, which can be successful or unsuccessful
  36 (&quot;condition&quot;) and end by an optional statement block.
  37 <ul>
  38   <li>When entering an alt statement, a snapshot is taken. A new snapshot is triggered by the statement <b><font face="Courier New" color="#003258" size="4">repeat</font></b>.</li>
  39   <li>It is possible to enable/disable an alternative by means of a Boolean expression placed between the brackets of the alternative.</li>
  40   <li>The last branch in an alt statement can be defined as an else branch by including the else keyword between the brackets of the alternative.</li>
  41   <li>alt statements may be nested.</li>
  42 </ul>
  43 <p>Related keywords:</p>
  44 <ul>
  45   <li><a href="repeat.html"><b><font face="Courier New" color="#003258" size="4">repeat</font></b></a></li>
  46   <li><a href="else.html"><b><font face="Courier New" color="#003258" size="4">else</font></b></a></li>
  47 </ul>
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  52     <td width="100%">
  53     <h3 align="left"><font face="Courier New" color="#003258" size="5"><b>alt {<br>
  54     &nbsp;&nbsp;&nbsp; [</b></font> [<i>guard_expression</i>] <font face="Courier New" color="#003258" size="5"><b>]</b></font> [<i>condition</i>] <font face="Courier New" color="#003258" size="5"><b>{</b></font>
  55     [<i>statement_block</i>] <font face="Courier New" color="#003258" size="5"><b>}<br>
  56     &nbsp;&nbsp;&nbsp; </b></font> ...<font face="Courier New" color="#003258" size="5"><b><br>
  57     };</b></font> &nbsp;</h3>
  58     </td>
  59   </tr>
  60 </table>
  61 </div>
  62 <ul>
  63   <li>
  64   <p>The <font face="Courier New" color="#003258" size="4"><b>alt</b></font> keyword introduces the branching definition.</p>
  65   </li>
  66   <li>
  67   <p>Each alternative begins with an optional <i>guard_expression</i> with the following options:</p>
  68   <ul>
  69     <li>empty guard (note that the brackets must be written) The <i>statement_block</i> will be executed if <i>condition</i> is met.&nbsp;</li>
  70     <li>Boolean expression. The <i>statement_block</i> will be executed if the Boolean expression evaluates to true AND <i>condition</i> is met.</li>
  71     <li>
  72     <p><font face="Courier New" color="#003258" size="4"><b>else</b></font> keyword. The <i>statement_block</i> will always be executed.&nbsp; No <i>condition</i> may appear in the branch.</p>
  73     </li>
  74   </ul>
  75   </li>
  76   <li>
  77   <p><i>condition</i> may be a communication or a timer event or the termination of a parallel test component. The following operations may be written here: <a href="receive.html"><b><font
  78     face="Courier New" color="#003258" size="4">receive</font></b></a>, <a href="trigger.html"><b><font face="Courier New" color="#003258" size="4">trigger</font></b></a>, <a href="getcall.html"><b><font
  79     face="Courier New" color="#003258" size="4">getcall</font></b></a>, <a href="getreply.html"><b><font face="Courier New" color="#003258" size="4">getreply</font></b></a>, <a href="catch.html"><b><font
  80     face="Courier New" color="#003258" size="4">catch</font></b></a>, <a href="check.html"><b><font face="Courier New" color="#003258" size="4">check</font></b></a>, <a href="timeout.html"><b><font
  81     face="Courier New" color="#003258" size="4">timeout</font></b></a> and <a href="done.html"><b><font face="Courier New" color="#003258" size="4">done</font></b></a>.</p>
  82   </li>
  83   <li>
  84   <p>The optional <i>statement_block</i> contains one or more statements separated by semicolons. When empty, the curly brackets must be written.</p>
  85   </li>
  86   <li>
  87   <p><b>...</b> indicates that&nbsp; several branches may occur in the <font face="Courier New" color="#003258" size="4"><b>alt</b></font> body. There is no separator between them.</p>
  88   </li>
  89 </ul>
  90 <hr align="left" width="50%">
  91 <p>Example:
  92 <p><font face="Courier New">alt {&nbsp;<br>
  93 &nbsp;&nbsp;&nbsp;[]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;L1_PCO.receive { setverdict(pass) }&nbsp;<br>
  94 &nbsp;&nbsp;&nbsp;[x&lt;=1] L2_PCO.receive { setverdict(inconc) }&nbsp;<br>
  95 &nbsp;&nbsp;&nbsp;[else]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{ setverdict(fail); stop }&nbsp;<br>
  96 };</font>
  97 <p>The first branch is activated if a message has been received on port L1_PCO. The verdict is set to pass. The second branch is activated if a message has been received on port L2_PCO and the
  98 variable x is not grater then one. In this case the verdict is set to inconclusive. The last branch is activated if none of the ports has received a messages. The verdict is set to fail and test
  99 execution is stopped.</p>
 100 <hr align="left" width="25%">
 101 <hr align="left" width="25%">
 102 <p><a HREF="BNF.html#altconstruct">BNF definition</a> of <font face="Courier New"> alt</font></p>
 103 </body>
 104 </html>