| <html><head><META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>4.3.4. Random Rule</title><link href="style.css" rel="stylesheet" type="text/css"><meta content="DocBook XSL Stylesheets V1.72.0" name="generator"><link rel="start" href="index.html" title="The VIATRA2 Model Transformation Framework"><link rel="up" href="sec_ASMCompoundRules.html" title="4.3. Compound ASM Rules"><link rel="prev" href="def_ParallelRule.html" title="4.3.3. Parallel Rule"><link rel="next" href="def_LetRule.html" title="4.3.5. Let Rule"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table summary="Navigation header" width="100%"><tr><th align="center" colspan="3">4.3.4. Random Rule</th></tr><tr><td align="left" width="20%"><a accesskey="p" href="def_ParallelRule.html">Prev</a> </td><th align="center" width="60%">4.3. Compound ASM Rules</th><td align="right" width="20%"> <a accesskey="n" href="def_LetRule.html">Next</a></td></tr></table><hr></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="def_RandomRule"></a>4.3.4. Random Rule</h4></div></div></div><div class="tip" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Tip: Description"><tr><td valign="top" align="center" rowspan="2" width="25"><img alt="[Tip]" src="images/tip.png"></td><th align="left"><a name="def_RandomRule_Description"></a>Description</th></tr><tr><td valign="top" align="left"><p> | |
| The <span class="strong"><strong>random rule</strong></span><a name="N1163C" class="indexterm"></a>is a rule-container; it executes a | |
| non-deterministically chosen rule from the rules listed inside. | |
| </p></td></tr></table></div><div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Important: Syntax"><tr><td valign="top" align="center" rowspan="2" width="25"><img alt="[Important]" src="images/important.png"></td><th align="left"><a name="def_RandomRule_Syntax"></a>Syntax</th></tr><tr><td valign="top" align="left"><pre class="programlisting"> | |
| RandomRuleAST ::= <span class="token">random</span> <span class="token">{</span> <a href="def_AsmRuleInvoc.html" title="4.1.2. ASM Rule Invocation">AsmRulesAST</a> <span class="token">}</span> OptSemicolonAST | |
| </pre><p> | |
| A <span class="strong"><strong>random rule</strong></span> contains an arbitrary number of other | |
| <a href="def_AsmRuleInvoc.html" title="4.1.2. ASM Rule Invocation">ASM rules</a>. | |
| </p></td></tr></table></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note: Semantics"><tr><td valign="top" align="center" rowspan="2" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left"><a name="def_RandomRule_Semantics"></a>Semantics</th></tr><tr><td valign="top" align="left"><p> | |
| The <span class="strong"><strong>random rule</strong></span> executes <span class="emphasis"><em>exactly one</em></span> rule from the nested rules. | |
| </p><p> | |
| The <span class="strong"><strong>random rule</strong></span> fails if the executed rule fails. | |
| No backtracking is provided upon failure, i.e. no other rules are selected if the previous rule fails. | |
| The previous state of local variables are not restored after failure. | |
| </p></td></tr></table></div><div class="highlights"><a name="def_RandomRule_DefinedIn"></a><p><b>Defined In: </b> | |
| <a href="def_CompoundRule.html" title="4.3.1. Compound Rule">compound rule</a> | |
| </p></div><div class="highlights"><a name="def_RandomRule_SeeAlso"></a><p><b>See Also: </b> | |
| <a href="def_SequentialRule.html" title="4.3.2. Sequential Rule">sequential rule</a>, <a href="def_ParallelRule.html" title="4.3.3. Parallel Rule">parallel rule</a> | |
| </p></div></div><div class="navfooter"><hr><table summary="Navigation footer" width="100%"><tr><td align="left" width="40%"><a accesskey="p" href="def_ParallelRule.html">Prev</a> </td><td align="center" width="20%"><a accesskey="u" href="sec_ASMCompoundRules.html">Up</a></td><td align="right" width="40%"> <a accesskey="n" href="def_LetRule.html">Next</a></td></tr><tr><td valign="top" align="left" width="40%">4.3.3. Parallel Rule </td><td align="center" width="20%"><a accesskey="h" href="index.html">Home</a></td><td valign="top" align="right" width="40%"> 4.3.5. Let Rule</td></tr></table></div></body></html> |