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<title>Metaprogramming tools</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.75.2"><link rel="home" href="index.html" title="Meta State Machine (MSM)"><link rel="up" href="ch06.html" title="Chapter 6. Internals"><link rel="prev" href="ch06s03.html" title="Generated state ids"><link rel="next" href="ch07.html" title="Chapter 7. Acknowledgements"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Metaprogramming tools</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch06s03.html">Prev</a> </td><th width="60%" align="center">Chapter 6. Internals</th><td width="20%" align="right"> <a accesskey="n" href="ch07.html">Next</a></td></tr></table><hr></div><div class="sect1" title="Metaprogramming tools"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="d0e3258"></a>Metaprogramming tools</h2></div></div></div><p>We can find for the transition table more uses than what we have seen so far.
Let's suppose you need to write a coverage tool. A state machine would be
perfect for such a job, if only it could provide some information about its
structure. Thanks to the transition table and Boost.MPL, it does.</p><p>What is needed for a coverage tool? You need to know how many states are
defined in the state machine, and how many events can be fired. This way you can
log the fired events and the states visited in the life of a concrete machine
and be able to perform some coverage analysis, like “fired 65% of all possible
events and visited 80% of the states defined in the state machine”. To achieve
this, MSM provides a few useful tools:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>generate_state_set<transition table>: returns a mpl::set of all
the states defined in the table.</p></li><li class="listitem"><p>generate_event_set<transition table>: returns a mpl::set of all
the events defined in the table.</p></li><li class="listitem"><p>using mpl::size<>::value you can get the number of elements in
the set.</p></li><li class="listitem"><p>display_type defines an operator() sending typeid(Type).name() to
cout.</p></li><li class="listitem"><p>fill_state_names fills an array of char const* with names of all
states (found by typeid)</p></li><li class="listitem"><p>using mpl::for_each on the result of generate_state_set and
generate_event_set passing display_type as argument will display all
the states of the state machine.</p></li><li class="listitem"><p>let's suppose you need to recursively find the states and events
defined in the composite states and thus also having a transition
table. Calling recursive_get_transition_table<Composite> will
return you the transition table of the composite state, recursively
adding the transition tables of all sub-state machines and
sub-sub...-sub-state machines. Then call generate_state_set or
generate_event_set on the result to get the full list of states and
events. </p></li></ul></div><p> An <a class="link" href="examples/BoostCon09Full.cpp" target="_top">example</a> shows the
tools in action. </p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch06s03.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch06.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch07.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"> Generated state ids </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 7. Acknowledgements</td></tr></table></div></body></html>
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