projects / deliverable / titan.core.git / blame
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|---|---|---|
| 970ed795 | 1 | <!-- |
| 3abe9331 | 2 | Copyright (c) 2000-2015 Ericsson Telecom AB |
| 970ed795 EL |
3 | |
| 4 | All rights reserved. This program and the accompanying materials | |
| 5 | are made available under the terms of the Eclipse Public License v1.0 | |
| 6 | which accompanies this distribution, and is available at | |
| 7 | http://www.eclipse.org/legal/epl-v10.html | |
| 8 | --> | |
| 9 | <html> | |
| 10 | <head> | |
| 11 | <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> | |
| 12 | <meta http-equiv="Content-Language" content="en-us"> | |
| 13 | <title>omit</title> | |
| 14 | </head> | |
| 15 | <body bgcolor="#DAD3C5" vlink="#0094D2" link="#003258"> | |
| 16 | <table align="left" border="0" cellspacing="0" cellpadding="0" valign=top> | |
| 17 | <tr> | |
| 18 | <td width=105 height=40><a href="https://projects.eclipse.org/projects/tools.titan"><img src="../images/titan_transparent.gif" border=0 width=105 height=40 align="left" alt="Titan"></a></td> | |
| 19 | </tr> | |
| 20 | </table> | |
| 21 | <table border="0" align="right" cellpadding="0" cellspacing="0"> | |
| 22 | <tr> | |
| 23 | <td><a href="../titan_main.html" alt="contents"><img border="0" src="../images/ao.jpg" width="53" height="40"></a></td> | |
| 24 | <td><a href="../titan_index.html" alt="index"><img border="0" src="../images/up.jpg" width="53" height="40"></a></td> | |
| 25 | <td><a href="of.html" alt="previous"><img border="0" src="../images/left.jpg" width="53" height="40"></a></td> | |
| 26 | <td><a href="on.html" alt="next"><img border="0" src="../images/right.jpg" width="53" height="40"></a></td> | |
| 27 | </tr> | |
| 28 | </table> | |
| 29 | <p><br clear="all"> | |
| 30 | </p> | |
| 31 | <hr> | |
| 32 | <h1>omit</h1> | |
| 33 | <hr align="left" width="75%"> | |
| 34 | <p>The <code>omit</code> keyword denotes the missing value. The <code>omit</code> can only be assigned to optional fields of <code>record</code> and <code>set</code> types to indicate that an | |
| 35 | optional field is not present. | |
| 36 | <hr align="left" width="50%"> | |
| 37 | <p>Related keywords:</p> | |
| 38 | <ul> | |
| 39 | <li><a href="optional.html"><b><font face="Courier New" color="#003258" size="4">optional</font></b></a></li> | |
| 40 | <li><a href="record.html"><b><font face="Courier New" color="#003258" size="4">record</font></b></a></li> | |
| 41 | <li><a href="set.html"><b><font face="Courier New" color="#003258" size="4">set</font></b></a></li> | |
| 42 | </ul> | |
| 43 | <hr align="left" width="50%"> | |
| 44 | <div align="center"> | |
| 45 | <center> | |
| 46 | <table border="0" width="90%" bgcolor="#FFB599" cellpadding="4"> | |
| 47 | <tr> | |
| 48 | <td width="100%"> | |
| 49 | <h3 align="center"><font face="Courier New" color="#003258" size="5"><b>omit</b></font></h3> | |
| 50 | </td> | |
| 51 | </tr> | |
| 52 | </table> | |
| 53 | </center> | |
| 54 | </div> | |
| 55 | <hr align="left" width="25%"> | |
| 56 | Example: | |
| 57 | <p><code> module m {<br> | |
| 58 | type record R { integer field1 optional, boolean field2 }<br> | |
| 59 | type set S { integer field1 optional, boolean field2 }<br> | |
| 60 | <br> | |
| 61 | control {<br> | |
| 62 | var R r1 := { omit, false };<br> | |
| 63 | var S s1 := { field1 := omit, field2 := true };<br> | |
| 64 | var S s2;<br> | |
| 65 | <br> | |
| 66 | s2.field1 := omit;<br> | |
| 67 | s2.field2 := false;<br> | |
| 68 | }<br> | |
| 69 | } </code> | |
| 70 | <p>Both type S and R contain an optional field1 element. Variable r1 is initialized using the value list notation; the optional field is omitted. Variable s1 is initialized using the value | |
| 71 | assignment notation; the optional field1 is not present. Finally, variable s2 is not initialized. Its fields are set via normal assignments through field references (i.e. using the dot notation); | |
| 72 | field1 is absent, again. | |
| 73 | <hr align="left" width="25%"> | |
| 74 | <p><a HREF="BNF.html#omitvalue">BNF definition</a> of <font face="Courier New">omit</font></p> | |
| 75 | </body> | |
| 76 | </html> |