<html><head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Back-end</title><link rel="stylesheet" href="boostbook.css" type="text/css"><meta name="generator" content="DocBook XSL-NS Stylesheets V1.75.2"><link rel="home" href="index.html" title="Meta State Machine (MSM) V2.10"><link rel="up" href="pt02.html" title="Part II. Reference"><link rel="prev" href="re01.html" title="Common headers"><link rel="next" href="re03.html" title="Front-end"></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">Back-end</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re01.html">Prev</a> </td><th width="60%" align="center">Part II. Reference</th><td width="20%" align="right"> <a accesskey="n" href="re03.html">Next</a></td></tr></table><hr></div><div class="refentry" title="Back-end"><a name="d0e5802"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>Back-end — The back-end headers</p></div><div class="refsect1" title="msm/back/state_machine.hpp"><a name="d0e5808"></a><h2>msm/back/state_machine.hpp</h2><p> This header provides one type, state_machine, MSM's state machine engine implementation.</p><pre class="classsynopsis"> <span class="ooclass"><span class="classname">template <class Derived,class HistoryPolicy=NoHistory,class CompilePolicy=favor_runtime_speed> state_machine</span></span> {<br>}</pre><div class="refsect2" title="Template arguments"><a name="d0e5817"></a><h3> Template arguments </h3><div class="refsect3" title="Derived"><a name="d0e5820"></a><h4> Derived </h4><p>The name of the front-end state machine definition. All three front-ends are possible.</p></div><div class="refsect3" title="HistoryPolicy"><a name="d0e5825"></a><h4> HistoryPolicy </h4><p>The desired history. This can be: AlwaysHistory, NoHistory, ShallowHistory. Default is NoHistory.</p></div><div class="refsect3" title="CompilePolicy"><a name="d0e5830"></a><h4> CompilePolicy </h4><p>The trade-off performance / compile-time. There are two predefined policies, favor_runtime_speed and favor_compile_time. Default is favor_runtime_speed, best performance, longer compile-time. See <a class="link" href="ch03s05.html#backend-tradeof-rt-ct">the backend</a>.</p></div></div><div class="refsect2" title="methods"><a name="d0e5838"></a><h3> methods </h3><div class="refsect3" title="start"><a name="d0e5841"></a><h4>start</h4><p> The start methods must be called before any call to process_event. It activates the entry action of the initial state(s). This allows you to choose when a state machine can start. See <a class="link" href="ch03s05.html#backend-start">backend</a>.</p><code class="methodsynopsis"><span class="methodname">void start</span>(<span class="methodparam"></span>);</code></div><div class="refsect3" title="process_event"><a name="d0e5854"></a><h4>process_event</h4><p>The event processing method implements the double-dispatch. Each call to this function with a new event type instantiates a new dispatch algorithm and increases compile-time.</p><code class="methodsynopsis"><span class="methodname">template <class Event> HandledEnum process_event</span>(<span class="methodparam">Event const&</span>);</code></div><div class="refsect3" title="current_state"><a name="d0e5865"></a><h4>current_state</h4><p>Returns the ids of currently active states. You will typically need it only for debugging or logging purposes.</p><code class="methodsynopsis"><span class="methodname">const int* current_state const</span>(<span class="methodparam"></span>);</code></div><div class="refsect3" title="get_state_by_id"><a name="d0e5875"></a><h4>get_state_by_id</h4><p>Returns the state whose id is given. As all states of a concrete state machine share a common base state, the return value is a base state. If the id corresponds to no state, a null pointer is returned.</p><code class="methodsynopsis"><span class="methodname">const BaseState* get_state_by_id const</span>(<span class="methodparam">int id</span>);</code></div><div class="refsect3" title="is_contained"><a name="d0e5886"></a><h4>is_contained</h4><p>Helper returning true if the state machine is contained as a submachine of another state machine.</p><code class="methodsynopsis"><span class="methodname">bool is_contained const</span>(<span class="methodparam"></span>);</code></div><div class="refsect3" title="get_state"><a name="d0e5896"></a><h4>get_state</h4><p>Returns the required state of the state machine as a pointer. A compile error will occur if the state is not to be found in the state machine.</p><code class="methodsynopsis"><span class="methodname">template <class State> State* get_state</span>(<span class="methodparam"></span>);</code></div><div class="refsect3" title="get_state"><a name="d0e5906"></a><h4>get_state</h4><p>Returns the required state of the state machine as a reference. A compile error will occur if the state is not to be found in the state machine.</p><code class="methodsynopsis"><span class="methodname">template <class State> State& get_state</span>(<span class="methodparam"></span>);</code></div><div class="refsect3" title="is_flag_active"><a name="d0e5916"></a><h4>is_flag_active</h4><p>Returns true if the given flag is currently active. A flag is active if the active state of one region is tagged with this flag (using OR as BinaryOp) or active states of <span class="underline">all</span> regions (using AND as BinaryOp)</p><code class="methodsynopsis"><span class="methodname">template <class Flag,class BinaryOp> bool is_flag_active</span>(<span class="methodparam"></span>);</code></div><div class="refsect3" title="is_flag_active"><a name="d0e5929"></a><h4>is_flag_active</h4><p>Returns true if the given flag is currently active. A flag is active if the active state of one region is tagged with this flag.</p><code class="methodsynopsis"><span class="methodname">template <class Flag> bool is_flag_active</span>(<span class="methodparam"></span>);</code></div><div class="refsect3" title="visit_current_states"><a name="d0e5939"></a><h4>visit_current_states</h4><p>Visits all active states and their substates. A state is visited using the <code class="code">accept</code> method without argument. The base class of all states must provide an <code class="code">accept_sig</code> type.</p><code class="methodsynopsis"><span class="methodname">void visit_current_states</span>(<span class="methodparam"></span>);</code></div><div class="refsect3" title="visit_current_states"><a name="d0e5955"></a><h4>visit_current_states</h4><p>Visits all active states and their substates. A state is visited using the <code class="code">accept</code> method with arguments. The base class of all states must provide an <code class="code">accept_sig</code> type defining the signature and thus the number and type of the parameters.</p><code class="methodsynopsis"><span class="methodname">void visit_current_states</span>(<span class="methodparam">any-type param1, any-type param2,...</span>);</code></div><div class="refsect3" title="defer_event"><a name="d0e5972"></a><h4>defer_event</h4><p> Defers the provided event. This method can be called only if at least one state defers an event or if the state machine provides the <code class="code">activate_deferred_events</code>(see <a class="link" href="examples/Orthogonal-deferred2.cpp" target="_top">example</a>) type either directly or using the deferred_events configuration of eUML (<code class="code">configure_ << deferred_events</code>)</p><code class="methodsynopsis"><span class="methodname">template <class Event> void defer_event</span>(<span class="methodparam">Event const&</span>);</code></div></div><div class="refsect2" title="Types"><a name="d0e5992"></a><h3>Types</h3><div class="refsect3" title="nr_regions"><a name="d0e5995"></a><h4>nr_regions </h4><p>The number of orthogonal regions contained in the state machine</p></div><div class="refsect3" title="entry_pt"><a name="d0e6000"></a><h4>entry_pt</h4><p>This nested type provides the necessary typedef for entry point pseudostates. <code class="code">state_machine<...>::entry_pt<state_name></code> is a transition's valid target inside the containing state machine's transition table.</p><pre class="classsynopsis"> <span class="ooclass"><span class="classname">entry_pt</span></span> {<br>}</pre></div><div class="refsect3" title="exit_pt"><a name="d0e6012"></a><h4>exit_pt</h4><p>This nested type provides the necessary typedef for exit point pseudostates. <code class="code">state_machine<...>::exit_pt<state_name></code> is a transition's valid source inside the containing state machine's transition table.</p><pre class="classsynopsis"> <span class="ooclass"><span class="classname">exit_pt</span></span> {<br>}</pre></div><div class="refsect3" title="direct"><a name="d0e6024"></a><h4>direct</h4><p>This nested type provides the necessary typedef for an explicit entry inside a submachine. <code class="code">state_machine<...>::direct<state_name></code> is a transition's valid target inside the containing state machine's transition table.</p><pre class="classsynopsis"> <span class="ooclass"><span class="classname">direct</span></span> {<br>}</pre></div><div class="refsect3" title="stt"><a name="d0e6036"></a><h4>stt</h4><p>Calling state_machine<frontend>::stt returns a mpl::vector containing the transition table of the state machine. This type can then be used with generate_state_set or generate_event_set.</p></div></div></div><div class="refsect1" title="args.hpp"><a name="d0e6041"></a><h2>args.hpp</h2><p>This header provides one type, args. which provides the necessary types for a visitor implementation.</p></div><div class="refsect1" title="msm/back/history_policies.hpp"><a name="d0e6046"></a><h2><span class="command"><strong><a name="history-interface"></a></strong></span>msm/back/history_policies.hpp</h2><p>This header provides the out-of-the-box history policies supported by MSM. There are 3 such policies.</p><div class="refsect2" title="Every history policy must implement the following methods:"><a name="d0e6052"></a><h3>Every history policy must implement the following methods: </h3><div class="refsect3" title="set_initial_states"><a name="d0e6055"></a><h4> set_initial_states </h4><p> This method is called by msm::back::state_machine when constructed. It gives the policy a chance to save the ids of all initial states (passed as array).</p><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void set_initial_states(</code></td><td><code>)</code>;</td><td> </td></tr></table><div class="paramdef-list"><code> <code>(</code>int* const<code>)</code> </code>;</div><div class="funcprototype-spacer"> </div></div></div><div class="refsect3" title="history_exit"><a name="d0e6069"></a><h4> history_exit </h4><p>This method is called by msm::back::state_machine when the submachine is exited. It gives the policy a chance to remember the ids of the last active substates of this submachine (passed as array).</p><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void history_exit(</code></td><td><code>)</code>;</td><td> </td></tr></table><div class="paramdef-list"><code> <code>(</code>int* const<code>)</code> </code>;</div><div class="funcprototype-spacer"> </div></div></div><div class="refsect3" title="history_entry"><a name="d0e6083"></a><h4> history_entry </h4><p>This method is called by msm::back::state_machine when the submachine is entered. It gives the policy a chance to set the active states according to the policy's aim. The policy gets as parameter the event which activated the submachine and returns an array of active states ids.</p><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">template <class Event> int* const history_exit(</code></td><td><code>)</code>;</td><td> </td></tr></table><div class="paramdef-list"><code> <code>(</code>Event const&<code>)</code> </code>;</div><div class="funcprototype-spacer"> </div></div></div></div><div class="refsect2" title="Out-of-the-box policies:"><a name="d0e6097"></a><h3>Out-of-the-box policies: </h3><div class="refsect3" title="NoHistory"><a name="d0e6100"></a><h4>NoHistory</h4><p>This policy is the default used by state_machine. No active state of a submachine is remembered and at every new activation of the submachine, the initial state(s) are activated. </p></div><div class="refsect3" title="AlwaysHistory"><a name="d0e6105"></a><h4>AlwaysHistory</h4><p>This policy is a non-UML-standard extension. The active state(s) of a submachine is (are) always remembered at every new activation of the submachine. </p></div><div class="refsect3" title="ShallowHistory"><a name="d0e6110"></a><h4>ShallowHistory</h4><p>This policy activates the active state(s) of a submachine if the event is found in the policy's event list. </p></div></div></div><div class="refsect1" title="msm/back/default_compile_policy.hpp"><a name="d0e6115"></a><h2>msm/back/default_compile_policy.hpp</h2><p>This header contains the definition of favor_runtime_speed. This policy has two settings:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Submachines dispatch faster because their transitions are added into their containing machine's transition table instead of simply forwarding events.</p></li><li class="listitem"><p>It solves transition conflicts at compile-time</p></li></ul></div></div><div class="refsect1" title="msm/back/favor_compile_time.hpp"><a name="d0e6127"></a><h2>msm/back/favor_compile_time.hpp</h2><p>This header contains the definition of favor_compile_time. This policy has two settings:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Submachines dispatch is slower because all events, even those with no dispatch chance, are forwarded to submachines. In exchange, no row is added into the containing machine's transition table, which reduces compile-time.</p></li><li class="listitem"><p>It solves transition conflicts at run-time.</p></li></ul></div></div><div class="refsect1" title="msm/back/metafunctions.hpp"><a name="d0e6139"></a><h2>msm/back/metafunctions.hpp </h2><p>This header contains metafunctions for use by the library. Three metafunctions can be useful for the user:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="code">generate_state_set< stt ></code>: generates the list of all states referenced by the transition table stt. If stt is a recursive table (generated by <code class="code">recursive_get_transition_table</code>), the metafunction finds recursively all states of the submachines. A non-recursive table can be obtained with some_backend_fsm::stt.</p></li><li class="listitem"><p><code class="code">generate_event_set< stt></code>: generates the list of all events referenced by the transition table stt. If stt is a recursive table (generated by <code class="code">recursive_get_transition_table</code>), the metafunction finds recursively all events of the submachines. A non-recursive table can be obtained with some_backend_fsm::stt.</p></li><li class="listitem"><p><code class="code">recursive_get_transition_table<fsm></code>: recursively extends the transition table of the state machine fsm with tables from the submachines.</p></li></ul></div></div><div class="refsect1" title="msm/back/tools.hpp"><a name="d0e6166"></a><h2>msm/back/tools.hpp </h2><p> This header contains a few metaprogramming tools to get some information out of a state machine.</p><div class="refsect2" title="fill_state_names"><a name="d0e6171"></a><h3>fill_state_names </h3><div class="refsect3" title="attributes"><a name="d0e6174"></a><h4>attributes </h4><p> fill_state_names has for attribute:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="code">char const** m_names</code>: an already allocated array of const char* where the typeid-generated names of a state machine states will be witten.</p></li></ul></div></div><div class="refsect3" title="constructor"><a name="d0e6185"></a><h4>constructor </h4><code class="constructorsynopsis"><span class="methodparam">char const** names_to_fill</span>(<span class="methodparam">char const** names_to_fill</span>);</code></div><div class="refsect3" title="usage"><a name="d0e6192"></a><h4>usage</h4><p> fill_state_names is made for use in a mpl::for_each iterating on a state list and writing inside a pre-allocated array the state names. Example:</p><pre class="programlisting">typedef some_fsm::stt Stt; typedef msm::back::generate_state_set<Stt>::type all_states; //states static char const* state_names[mpl::size<all_states>::value]; // array to fill with names // fill the names of the states defined in the state machine mpl::for_each<all_states,boost::msm::wrap<mpl::placeholders::_1> > (msm::back::fill_state_names<Stt>(state_names)); // display all active states for (unsigned int i=0;i<some_fsm::nr_regions::value;++i) { std::cout << " -> " << state_names[my_fsm_instance.current_state()[i]] << std::endl; }</pre></div></div><div class="refsect2" title="get_state_name"><a name="d0e6199"></a><h3>get_state_name </h3><div class="refsect3" title="attributes"><a name="d0e6202"></a><h4> attributes </h4><p>get_state_name has for attributes:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>std::string& m_name: the return value of the iteration</p></li><li class="listitem"><p>int m_state_id: the searched state's id</p></li></ul></div></div><div class="refsect3" title="constructor"><a name="d0e6214"></a><h4>constructor</h4><p>The constructor takes as argument a reference to the string to fill with the state name and the id which must be searched.</p><code class="constructorsynopsis"><span class="methodparam">string& name_to_fill,int state_id</span>(<span class="methodparam">string& name_to_fill,int state_id</span>);</code></div><div class="refsect3" title="usage"><a name="d0e6223"></a><h4> usage</h4><p>This type is made for the same search as in the previous example, using a mpl::for_each to iterate on states. After the iteration, the state name reference has been set.</p></div></div><div class="refsect2" title="display_type"><a name="d0e6228"></a><h3>display_type </h3><div class="refsect3" title="attributes"><a name="d0e6231"></a><h4> attributes </h4><p>none</p></div><div class="refsect3" title="usage"><a name="d0e6236"></a><h4> usage</h4><p>Reusing the state list from the previous example, we can output all state names:</p><p><code class="code">mpl::for_each<all_states,boost::msm::wrap<mpl::placeholders::_1> >(msm::back::display_type ());</code></p></div></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re01.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="pt02.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re03.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Common headers </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Front-end</td></tr></table></div></body></html>