Fix most of the system docs and emacs mode

9 files changed, 281 insertions, 83 deletions

diff --git a/lib/sasl/doc/src/appup.xml b/lib/sasl/doc/src/appup.xml
index b54d2adb19..6fbdcb9f5b 100644
--- a/lib/sasl/doc/src/appup.xml
+++ b/lib/sasl/doc/src/appup.xml
@@ -4,7 +4,7 @@
 <fileref>
   <header>
     <copyright>
-      <year>1997</year><year>2014</year>
+      <year>1997</year><year>2016</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -137,7 +137,8 @@
       code change. If it is set to <c>{advanced,Extra}</c>, implemented
       processes using 
       <seealso marker="stdlib:gen_server"><c>gen_server</c></seealso>, 
-      <seealso marker="stdlib:gen_fsm"><c>gen_fsm</c></seealso>, or
+      <seealso marker="stdlib:gen_fsm"><c>gen_fsm</c></seealso>,
+      <seealso marker="stdlib:gen_statem"><c>gen_statem</c></seealso>, or
       <seealso marker="stdlib:gen_event"><c>gen_event</c></seealso> 
       transform their internal state by calling the callback function
       <c>code_change</c>. Special processes call the callback
diff --git a/lib/sasl/doc/src/error_logging.xml b/lib/sasl/doc/src/error_logging.xml
index 46b12f3872..8464a41ff9 100644
--- a/lib/sasl/doc/src/error_logging.xml
+++ b/lib/sasl/doc/src/error_logging.xml
@@ -4,7 +4,7 @@
 <chapter>
   <header>
     <copyright>
-      <year>1997</year><year>2013</year>
+      <year>1997</year><year>2016</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -90,8 +90,9 @@
       a process terminates with an unexpected reason, which is any reason 
       other than <c>normal</c>, <c>shutdown</c>, or <c>{shutdown,Term}</c>.
       Processes using behaviors
-      <seealso marker="stdlib:gen_server"><c>gen_server</c></seealso> or 
-      <seealso marker="stdlib:gen_fsm"><c>gen_fsm</c></seealso> 
+      <seealso marker="stdlib:gen_server"><c>gen_server</c></seealso>,
+      <seealso marker="stdlib:gen_fsm"><c>gen_fsm</c></seealso> or
+      <seealso marker="stdlib:gen_statem"><c>gen_statem</c></seealso>
       are examples of such processes. A crash report contains the following items:</p>
     <taglist>
       <tag><c>Crasher</c></tag>
diff --git a/lib/stdlib/doc/src/gen_statem.xml b/lib/stdlib/doc/src/gen_statem.xml
index 01be3099c1..db6a4e03ea 100644
--- a/lib/stdlib/doc/src/gen_statem.xml
+++ b/lib/stdlib/doc/src/gen_statem.xml
@@ -407,7 +407,7 @@ ok
       <name name="state" />
       <desc>
 	<p>
-	  After a state change (<c>NewState =/= State</c>)
+	  After a state change (<c>NextState =/= State</c>)
 	  all postponed events are retried.
 	</p>
       </desc>
@@ -566,7 +566,7 @@ ok
 	<p>
 	  If <c>true</c> postpone the current event and retry
 	  it when the state changes that is:
-	  <c>NewState =/= State</c>.
+	  <c>NextState =/= State</c>.
 	</p>
       </desc>
     </datatype>
@@ -701,7 +701,47 @@ ok
       </desc>
     </datatype>
     <datatype>
-      <name name="state_callback_result" />
+      <name name="state_function_result" />
+      <desc>
+	<taglist>
+	  <tag><c>next_state</c></tag>
+	  <item>
+	    The <c>gen_statem</c> will do a state transition to
+	    <c><anno>NextStateName</anno></c>
+	    (which may be the same as the current state),
+	    set <c><anno>NewData</anno></c>
+	    and execute all <c><anno>Actions</anno></c>
+	  </item>
+	</taglist>
+	<p>
+	  All these terms are tuples or atoms and this property
+	  will hold in any future version of <c>gen_statem</c>,
+	  just in case you need such a promise.
+	</p>
+      </desc>
+    </datatype>
+    <datatype>
+      <name name="handle_event_result" />
+      <desc>
+	<taglist>
+	  <tag><c>next_state</c></tag>
+	  <item>
+	    The <c>gen_statem</c> will do a state transition to
+	    <c><anno>NextState</anno></c>
+	    (which may be the same as the current state),
+	    set <c><anno>NewData</anno></c>
+	    and execute all <c><anno>Actions</anno></c>
+	  </item>
+	</taglist>
+	<p>
+	  All these terms are tuples or atoms and this property
+	  will hold in any future version of <c>gen_statem</c>,
+	  just in case you need such a promise.
+	</p>
+      </desc>
+    </datatype>
+    <datatype>
+      <name name="common_state_callback_result" />
       <desc>
 	<taglist>
 	  <tag><c>stop</c></tag>
@@ -723,14 +763,6 @@ ok
 	    with <c>Reason</c> and
 	    <c><anno>NewData</anno></c>, if given.
 	  </item>
-	  <tag><c>next_state</c></tag>
-	  <item>
-	    The <c>gen_statem</c> will do a state transition to
-	    <c><anno>NewState</anno></c>
-	    (which may be the same as the current state),
-	    set <c><anno>NewData</anno></c>
-	    and execute all <c><anno>Actions</anno></c>
-	  </item>
 	  <tag><c>keep_state</c></tag>
 	  <item>
 	    The <c>gen_statem</c> will keep the current state, or
@@ -1209,10 +1241,11 @@ ok
     </func>
 
     <func>
-      <name>Module:StateName(EventType, EventContent, Data) -> Result
+      <name>Module:StateName(EventType, EventContent, Data) ->
+      StateFunctionResult
       </name>
       <name>Module:handle_event(EventType, EventContent,
-      State, Data) -> Result
+      State, Data) -> HandleEventResult
       </name>
       <fsummary>Handle an event</fsummary>
       <type>
@@ -1222,7 +1255,7 @@ ok
 	</v>
 	<v>EventContent = term()</v>
 	<v>
-	  State = NewState =
+	  State =
 	  <seealso marker="#type-state">state()</seealso>
 	</v>
 	<v>
@@ -1230,9 +1263,15 @@ ok
 	  <seealso marker="#type-data">data()</seealso>
 	</v>
 	<v>
-	  Result =
-	  <seealso marker="#type-state_callback_result">
-	    state_callback_result()
+	  StateFunctionResult =
+	  <seealso marker="#type-state_function_result">
+	    state_function_result()
+	  </seealso>
+	</v>
+	<v>
+	  HandleEventResult =
+	  <seealso marker="#type-handle_event_result">
+	    handle_event_result()
 	  </seealso>
 	</v>
       </type>
@@ -1260,9 +1299,15 @@ ok
 	  <seealso marker="#reply/2"><c>reply(Caller, Reply)</c></seealso>.
 	</p>
 	<p>
-	  If this function returns with a new state that
+	  If this function returns with a next state that
 	  does not match equal (<c>=/=</c>) to the current state
-	  all postponed events will be retried in the new state.
+	  all postponed events will be retried in the next state.
+	</p>
+	<p>
+	  The only difference between <c>StateFunctionResult</c> and
+	  <c>HandleEventResult</c> is that for <c>StateFunctionResult</c>
+	  the next state has to be an atom but for <c>HandleEventResult</c>
+	  there is no restriction on the next state.
 	</p>
 	<p>
 	  See <seealso marker="#type-action">action()</seealso>
@@ -1272,7 +1317,7 @@ ok
 	<p>
 	  These functions may use
 	  <seealso marker="erts:erlang#throw/1"><c>throw</c></seealso>,
-	  to return <c>Result</c>.
+	  to return the result.
 	</p>
       </desc>
     </func>
@@ -1401,7 +1446,7 @@ ok
         <p>
 	  If successful, the function shall return the updated
           internal state in an
-	  <c>{ok,{NewState,NewData}}</c> tuple.
+	  <c>{ok,NewState,NewData}</c> tuple.
 	</p>
 	<p>
 	  If the function returns <c>Reason</c>, the ongoing
diff --git a/lib/stdlib/doc/src/proc_lib.xml b/lib/stdlib/doc/src/proc_lib.xml
index 85f0c0c908..245580b1ba 100644
--- a/lib/stdlib/doc/src/proc_lib.xml
+++ b/lib/stdlib/doc/src/proc_lib.xml
@@ -4,7 +4,7 @@
 <erlref>
   <header>
     <copyright>
-      <year>1996</year><year>2014</year>
+      <year>1996</year><year>2016</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -34,9 +34,9 @@
     <p>This module is used to start processes adhering to
       the <seealso marker="doc/design_principles:des_princ">OTP Design Principles</seealso>. Specifically, the functions in this
       module are used by the OTP standard behaviors (<c>gen_server</c>,
-      <c>gen_fsm</c>, ...) when starting new processes. The functions
-      can also be used to start <em>special processes</em>, user
-      defined processes which comply to the OTP design principles. See
+      <c>gen_fsm</c>, <c>gen_statem</c>, ...) when starting new processes.
+      The functions can also be used to start <em>special processes</em>,
+      user defined processes which comply to the OTP design principles. See
       <seealso marker="doc/design_principles:spec_proc">Sys and Proc_Lib</seealso> in OTP Design Principles for an example.</p>
     <p>Some useful information is initialized when a process starts.
       The registered names, or the process identifiers, of the parent
diff --git a/lib/stdlib/doc/src/supervisor.xml b/lib/stdlib/doc/src/supervisor.xml
index 24ff251ce3..9d81fb0db7 100644
--- a/lib/stdlib/doc/src/supervisor.xml
+++ b/lib/stdlib/doc/src/supervisor.xml
@@ -4,7 +4,7 @@
 <erlref>
   <header>
     <copyright>
-      <year>1996</year><year>2014</year>
+      <year>1996</year><year>2016</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -34,8 +34,8 @@
     <p>A behaviour module for implementing a supervisor, a process which
       supervises other processes called child processes. A child
       process can either be another supervisor or a worker process.
-      Worker processes are normally implemented using one of
-      the <c>gen_event</c>, <c>gen_fsm</c>, or <c>gen_server</c>
+      Worker processes are normally implemented using one of the
+      <c>gen_event</c>, <c>gen_fsm</c>, <c>gen_statem</c> or <c>gen_server</c>
       behaviours. A supervisor implemented using this module will have
       a standard set of interface functions and include functionality
       for tracing and error reporting. Supervisors are used to build a
@@ -221,7 +221,8 @@
         <p><c>modules</c> is used by the release handler during code
           replacement to determine which processes are using a certain
           module. As a rule of thumb, if the child process is a
-          <c>supervisor</c>, <c>gen_server</c>, or <c>gen_fsm</c>,
+          <c>supervisor</c>, <c>gen_server</c>,
+	  <c>gen_fsm</c> or <c>gen_statem</c>
 	  this should be a list with one element <c>[Module]</c>,
 	  where <c>Module</c> is the callback module. If the child
 	  process is an event manager (<c>gen_event</c>) with a
@@ -633,6 +634,7 @@
     <title>SEE ALSO</title>
     <p><seealso marker="gen_event">gen_event(3)</seealso>, 
       <seealso marker="gen_fsm">gen_fsm(3)</seealso>, 
+      <seealso marker="gen_statem">gen_statem(3)</seealso>,
       <seealso marker="gen_server">gen_server(3)</seealso>, 
       <seealso marker="sys">sys(3)</seealso></p>
   </section>
diff --git a/lib/stdlib/doc/src/sys.xml b/lib/stdlib/doc/src/sys.xml
index d400f72e1d..2255395f46 100644
--- a/lib/stdlib/doc/src/sys.xml
+++ b/lib/stdlib/doc/src/sys.xml
@@ -4,7 +4,7 @@
 <erlref>
   <header>
     <copyright>
-      <year>1996</year><year>2014</year>
+      <year>1996</year><year>2016</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -217,14 +217,18 @@
           processes. For example, a <c>gen_server</c> process returns
           the callback module's state, a <c>gen_fsm</c> process
           returns information such as its current state name and state data,
-          and a <c>gen_event</c> process returns information about each of its
+	  a <c>gen_statem</c> process returns information about
+	  its current state and data, and a <c>gen_event</c> process
+	  returns information about each of its
           registered handlers. Callback modules for <c>gen_server</c>,
-          <c>gen_fsm</c>, and <c>gen_event</c> can also customise the value
+          <c>gen_fsm</c>, <c>gen_statem</c> and <c>gen_event</c>
+	  can also customise the value
           of <c><anno>Misc</anno></c> by exporting a <c>format_status/2</c>
           function that contributes module-specific information;
-          see <seealso marker="gen_server#Module:format_status/2">gen_server:format_status/2</seealso>,
-          <seealso marker="gen_fsm#Module:format_status/2">gen_fsm:format_status/2</seealso>, and
-          <seealso marker="gen_event#Module:format_status/2">gen_event:format_status/2</seealso>
+          see <seealso marker="gen_server#Module:format_status/2">gen_server format_status/2</seealso>,
+          <seealso marker="gen_fsm#Module:format_status/2">gen_fsm format_status/2</seealso>,
+          <seealso marker="gen_statem#Module:format_status/2">gen_statem format_status/2</seealso>, and
+          <seealso marker="gen_event#Module:format_status/2">gen_event format_status/2</seealso>
           for more details.</p>
       </desc>
     </func>
@@ -245,6 +249,8 @@
           processes. For a <c>gen_server</c> process, the returned <c><anno>State</anno></c>
           is simply the callback module's state. For a <c>gen_fsm</c> process,
           <c><anno>State</anno></c> is the tuple <c>{CurrentStateName, CurrentStateData}</c>.
+	  For a <c>gen_statem</c> process <c><anno>State</anno></c> is
+	  the tuple <c>{CurrentState,CurrentData}.</c>
           For a <c>gen_event</c> process, <c><anno>State</anno></c> a list of tuples,
           where each tuple corresponds to an event handler registered in the process and contains
           <c>{Module, Id, HandlerState}</c>, where <c>Module</c> is the event handler's module name,
@@ -263,8 +269,9 @@
           details of the exception.</p>
         <p>The <c>system_get_state/1</c> function is primarily useful for user-defined
           behaviours and modules that implement OTP <seealso marker="#special_process">special
-          processes</seealso>. The <c>gen_server</c>, <c>gen_fsm</c>, and <c>gen_event</c> OTP
-          behaviour modules export this function, and so callback modules for those behaviours
+          processes</seealso>. The <c>gen_server</c>, <c>gen_fsm</c>,
+	  <c>gen_statem</c> and <c>gen_event</c> OTP
+          behaviour modules export this function, so callback modules for those behaviours
           need not supply their own.</p>
         <p>To obtain more information about a process, including its state, see
           <seealso marker="#get_status-1">get_status/1</seealso> and
@@ -290,6 +297,8 @@
           <c>gen_fsm</c> process, <c><anno>State</anno></c> is the tuple
           <c>{CurrentStateName, CurrentStateData}</c>, and <c><anno>NewState</anno></c>
           is a similar tuple that may contain a new state name, new state data, or both.
+	  The same applies for a <c>gen_statem</c> process but
+	  it names the tuple fields <c>{CurrentState,CurrentData}</c>.
           For a <c>gen_event</c> process, <c><anno>State</anno></c> is the tuple
           <c>{Module, Id, HandlerState}</c> where <c>Module</c> is the event handler's module name,
           <c>Id</c> is the handler's ID (which is the value <c>false</c> if it was registered without
@@ -304,7 +313,8 @@
           state, then regardless of process type, it may simply return its <c><anno>State</anno></c>
           argument.</p>
         <p>If a <c><anno>StateFun</anno></c> function crashes or throws an exception, then
-          for <c>gen_server</c> and <c>gen_fsm</c> processes, the original state of the process is
+          for <c>gen_server</c>, <c>gen_fsm</c> or <c>gen_statem</c> processes,
+	  the original state of the process is
           unchanged. For <c>gen_event</c> processes, a crashing or failing <c><anno>StateFun</anno></c>
           function means that only the state of the particular event handler it was working on when it
           failed or crashed is unchanged; it can still succeed in changing the states of other event
@@ -329,7 +339,8 @@
           <c>{callback_failed, StateFun, {Class, Reason}}</c>.</p>
         <p>The <c>system_replace_state/2</c> function is primarily useful for user-defined behaviours and
           modules that implement OTP <seealso marker="#special_process">special processes</seealso>. The
-          <c>gen_server</c>, <c>gen_fsm</c>, and <c>gen_event</c> OTP behaviour modules export this function,
+          <c>gen_server</c>, <c>gen_fsm</c>, <c>gen_statem</c> and
+	  <c>gen_event</c> OTP behaviour modules export this function,
           and so callback modules for those behaviours need not supply their own.</p>
       </desc>
     </func>
diff --git a/lib/stdlib/src/gen_statem.erl b/lib/stdlib/src/gen_statem.erl
index cc09efc140..438c366f8e 100644
--- a/lib/stdlib/src/gen_statem.erl
+++ b/lib/stdlib/src/gen_statem.erl
@@ -44,8 +44,16 @@
 -export(
    [wakeup_from_hibernate/3]).
 
+%% Type exports for templates
+-export_type(
+   [event_type/0,
+    callback_mode/0,
+    state_function_result/0,
+    handle_event_result/0,
+    action/0]).
+
 %% Fix problem for doc build
--export_type([transition_option/0,state_callback_result/0]).
+-export_type([transition_option/0]).
 
 %%%==========================================================================
 %%% Interface functions.
@@ -84,7 +92,7 @@
 
 -type action() ::
 	%% During a state change:
-	%% * NewState and NewData are set.
+	%% * NextState and NewData are set.
 	%% * All action()s are executed in order of apperance.
 	%% * Postponing the current event is performed
 	%%   iff 'postpone' is 'true'.
@@ -119,7 +127,25 @@
 	{'reply', % Reply to a caller
 	 Caller :: caller(), Reply :: term()}.
 
--type state_callback_result() ::
+-type state_function_result() ::
+	{'next_state', % {next_state,NextStateName,NewData,[]}
+	 NextStateName :: state_name(),
+	 NewData :: data()} |
+	{'next_state', % State transition, maybe to the same state
+	 NextStateName :: state_name(),
+	 NewData :: data(),
+	 Actions :: [action()] | action()} |
+	common_state_callback_result().
+-type handle_event_result() ::
+	{'next_state', % {next_state,NextState,NewData,[]}
+	 NextState :: state(),
+	 NewData :: data()} |
+	{'next_state', % State transition, maybe to the same state
+	 NextState :: state(),
+	 NewData :: data(),
+	 Actions :: [action()] | action()} |
+	common_state_callback_result().
+-type common_state_callback_result() ::
 	'stop' | % {stop,normal}
 	{'stop', % Stop the server
 	 Reason :: term()} |
@@ -133,13 +159,6 @@
 	 Reason :: term(),
 	 Replies :: [reply_action()] | reply_action(),
 	 NewData :: data()} |
-	{'next_state', % {next_state,NewState,NewData,[]}
-	 NewState :: state(),
-	 NewData :: data()} |
-	{'next_state', % State transition, maybe to the same state
-	 NewState :: state(),
-	 NewData :: data(),
-	 Actions :: [action()] | action()} |
 	{'keep_state', % {keep_state,NewData,[]}
 	 NewData :: data()} |
 	{'keep_state', % Keep state, change data
@@ -171,7 +190,7 @@
 	    event_type(),
 	    EventContent :: term(),
 	    Data :: data()) ->
-    state_callback_result().
+    state_function_result().
 %%
 %% State callback for callback_mode() =:= handle_event_function.
 %%
@@ -182,7 +201,7 @@
 	    EventContent :: term(),
 	    State :: state(), % Current state
 	    Data :: data()) ->
-    state_callback_result().
+    handle_event_result().
 
 %% Clean up before the server terminates.
 -callback terminate(
@@ -514,7 +533,7 @@ enter(Module, Opts, CallbackMode, State, Data, Server, Actions, Parent) ->
     %% The values should already have been type checked
     Name = gen:get_proc_name(Server),
     Debug = gen:debug_options(Name, Opts),
-    OldState = make_ref(), % Will be discarded by loop_event_actions/9
+    PrevState = make_ref(), % Will be discarded by loop_event_actions/9
     NewActions =
 	if
 	    is_list(Actions) ->
@@ -526,7 +545,7 @@ enter(Module, Opts, CallbackMode, State, Data, Server, Actions, Parent) ->
       callback_mode => CallbackMode,
       module => Module,
       name => Name,
-      state => OldState,
+      state => PrevState,
       data => Data,
       timer => undefined,
       postponed => [],
@@ -534,7 +553,7 @@ enter(Module, Opts, CallbackMode, State, Data, Server, Actions, Parent) ->
     loop_event_actions(
       Parent, Debug, S, [],
       {event,undefined}, % Will be discarded thanks to {postpone,false}
-      OldState, State, Data, NewActions).
+      PrevState, State, Data, NewActions).
 
 %%%==========================================================================
 %%%  gen callbacks
@@ -868,18 +887,18 @@ loop_event_result(
 		  exit, Reason, ?STACKTRACE(), Debug, NewS, Q, Replies),
 	    %% Since we got back here Replies was bad
 	    terminate(Class, NewReason, Stacktrace, NewDebug, NewS, Q);
-	{next_state,NewState,NewData}
-	  when CallbackMode =:= state_functions, is_atom(NewState);
+	{next_state,NextState,NewData}
+	  when CallbackMode =:= state_functions, is_atom(NextState);
 	       CallbackMode =/= state_functions ->
 	    loop_event_actions(
 	      Parent, Debug, S, Events, Event,
-	      State, NewState, NewData, []);
-	{next_state,NewState,NewData,Actions}
-	  when CallbackMode =:= state_functions, is_atom(NewState);
+	      State, NextState, NewData, []);
+	{next_state,NextState,NewData,Actions}
+	  when CallbackMode =:= state_functions, is_atom(NextState);
 	       CallbackMode =/= state_functions ->
 	    loop_event_actions(
 	      Parent, Debug, S, Events, Event,
-	      State, NewState, NewData, Actions);
+	      State, NextState, NewData, Actions);
 	{keep_state,NewData} ->
 	    loop_event_actions(
 	      Parent, Debug, S, Events, Event,
@@ -902,13 +921,13 @@ loop_event_result(
     end.
 
 loop_event_actions(
-  Parent, Debug, S, Events, Event, State, NewState, NewData, Actions) ->
+  Parent, Debug, S, Events, Event, State, NextState, NewData, Actions) ->
     Postpone = false, % Shall we postpone this event, true or false
     Hibernate = false,
     Timeout = undefined,
     NextEvents = [],
     loop_event_actions(
-      Parent, Debug, S, Events, Event, State, NewState, NewData,
+      Parent, Debug, S, Events, Event, State, NextState, NewData,
       if
 	  is_list(Actions) ->
 	      Actions;
@@ -920,19 +939,19 @@ loop_event_actions(
 %% Process all action()s
 loop_event_actions(
   Parent, Debug, S, Events, Event,
-  State, NewState, NewData, [Action|Actions],
+  State, NextState, NewData, [Action|Actions],
   Postpone, Hibernate, Timeout, NextEvents) ->
     case Action of
 	%% Actions that set options
 	postpone ->
 	    loop_event_actions(
 	      Parent, Debug, S, Events, Event,
-	      State, NewState, NewData, Actions,
+	      State, NextState, NewData, Actions,
 	      true, Hibernate, Timeout, NextEvents);
 	{postpone,NewPostpone} when is_boolean(NewPostpone) ->
 	    loop_event_actions(
 	      Parent, Debug, S, Events, Event,
-	      State, NewState, NewData, Actions,
+	      State, NextState, NewData, Actions,
 	      NewPostpone, Hibernate, Timeout, NextEvents);
 	{postpone,_} ->
 	    ?TERMINATE(
@@ -940,12 +959,12 @@ loop_event_actions(
 	hibernate ->
 	    loop_event_actions(
 	      Parent, Debug, S, Events, Event,
-	      State, NewState, NewData, Actions,
+	      State, NextState, NewData, Actions,
 	      Postpone, true, Timeout, NextEvents);
 	{hibernate,NewHibernate} when is_boolean(NewHibernate) ->
 	    loop_event_actions(
 	      Parent, Debug, S, Events, Event,
-	      State, NewState, NewData, Actions,
+	      State, NextState, NewData, Actions,
 	      Postpone, NewHibernate, Timeout, NextEvents);
 	{hibernate,_} ->
 	    ?TERMINATE(
@@ -953,12 +972,12 @@ loop_event_actions(
 	{timeout,infinity,_} -> % Clear timer - it will never trigger
 	    loop_event_actions(
 	      Parent, Debug, S, Events, Event,
-	      State, NewState, NewData, Actions,
+	      State, NextState, NewData, Actions,
 	      Postpone, Hibernate, undefined, NextEvents);
 	{timeout,Time,_} = NewTimeout when is_integer(Time), Time >= 0 ->
 	    loop_event_actions(
 	      Parent, Debug, S, Events, Event,
-	      State, NewState, NewData, Actions,
+	      State, NextState, NewData, Actions,
 	      Postpone, Hibernate, NewTimeout, NextEvents);
 	{timeout,_,_} ->
 	    ?TERMINATE(
@@ -970,7 +989,7 @@ loop_event_actions(
 		    NewDebug = do_reply(Debug, S, Caller, Reply),
 		    loop_event_actions(
 		      Parent, NewDebug, S, Events, Event,
-		      State, NewState, NewData, Actions,
+		      State, NextState, NewData, Actions,
 		      Postpone, Hibernate, Timeout, NextEvents);
 		false ->
 		    ?TERMINATE(
@@ -981,7 +1000,7 @@ loop_event_actions(
 		true ->
 		    loop_event_actions(
 		      Parent, Debug, S, Events, Event,
-		      State, NewState, NewData, Actions,
+		      State, NextState, NewData, Actions,
 		      Postpone, Hibernate, Timeout,
 		      [{Type,Content}|NextEvents]);
 		false ->
@@ -996,7 +1015,7 @@ loop_event_actions(
 %% End of actions list
 loop_event_actions(
   Parent, Debug, #{postponed := P0} = S, Events, Event,
-  State, NewState, NewData, [],
+  State, NextState, NewData, [],
   Postpone, Hibernate, Timeout, NextEvents) ->
     %%
     %% All options have been collected and next_events are buffered.
@@ -1011,7 +1030,7 @@ loop_event_actions(
 	end,
     {Q2,P} = % Move all postponed events to queue if state change
 	if
-	    NewState =:= State ->
+	    NextState =:= State ->
 		{Events,P1};
 	    true ->
 		{lists:reverse(P1, Events),[]}
@@ -1024,9 +1043,9 @@ loop_event_actions(
 	  Debug, S,
 	  case Postpone of
 	      true ->
-		  {postpone,Event,NewState};
+		  {postpone,Event,NextState};
 	      false ->
-		  {consume,Event,NewState}
+		  {consume,Event,NextState}
 	  end),
     %% Have a peek on the event queue so we can avoid starting
     %% the state timer unless we have to
@@ -1057,7 +1076,7 @@ loop_event_actions(
     loop_events(
       Parent, NewDebug,
       S#{
-	state := NewState,
+	state := NextState,
 	data := NewData,
 	timer := Timer,
 	postponed := P,
diff --git a/lib/tools/doc/src/erlang_mode.xml b/lib/tools/doc/src/erlang_mode.xml
index 4ecb8feadd..00cf5196b4 100644
--- a/lib/tools/doc/src/erlang_mode.xml
+++ b/lib/tools/doc/src/erlang_mode.xml
@@ -4,7 +4,7 @@
 <erlref>
   <header>
     <copyright>
-      <year>2003</year><year>2013</year>
+      <year>2003</year><year>2016</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -252,6 +252,7 @@
        behavior</item>
       <item>gen_event - skeleton for the OTP gen_event behavior</item>
       <item>gen_fsm - skeleton for the OTP gen_fsm behavior</item>
+      <item>gen_statem - skeleton for the OTP gen_statem behavior</item>
       <item>Library module - skeleton for a module that does not
        implement a process.</item>
       <item>Corba callback - skeleton for a Corba callback module.</item>
diff --git a/lib/tools/emacs/erlang-skels.el b/lib/tools/emacs/erlang-skels.el
index 6880ec733c..cdf09ad502 100644
--- a/lib/tools/emacs/erlang-skels.el
+++ b/lib/tools/emacs/erlang-skels.el
@@ -1,7 +1,7 @@
 ;;
 ;; %CopyrightBegin%
 ;;
-;; Copyright Ericsson AB 2010-2014. All Rights Reserved.
+;; Copyright Ericsson AB 2010-2016. All Rights Reserved.
 ;;
 ;; Licensed under the Apache License, Version 2.0 (the "License");
 ;; you may not use this file except in compliance with the License.
@@ -56,6 +56,8 @@
      erlang-skel-gen-event erlang-skel-header)
     ("gen_fsm" "gen-fsm"
      erlang-skel-gen-fsm erlang-skel-header)
+    ("gen_statem" "gen-statem"
+     erlang-skel-gen-statem erlang-skel-header)
     ("wx_object" "wx-object"
      erlang-skel-wx-object erlang-skel-header)
     ("Library module" "gen-lib"
@@ -858,6 +860,122 @@ Please see the function `tempo-define-template'.")
   "*The template of a gen_fsm.
 Please see the function `tempo-define-template'.")
 
+(defvar erlang-skel-gen-statem
+  '((erlang-skel-include erlang-skel-large-header)
+    "-behaviour(gen_statem)." n n
+
+    "%% API" n
+    "-export([start_link/0])." n
+    n
+    "%% gen_statem callbacks" n
+    "-export([init/1, terminate/3, code_change/4])." n
+    "-export([state_name/3])." n
+    "-export([handle_event/4])." n
+    n
+    "-define(SERVER, ?MODULE)." n
+    n
+    "-record(data, {})." n
+    n
+    (erlang-skel-double-separator-start 3)
+    "%%% API" n
+    (erlang-skel-double-separator-end 3) n
+    (erlang-skel-separator-start 2)
+    "%% @doc" n
+    "%% Creates a gen_statem process which calls Module:init/1 to" n
+    "%% initialize. To ensure a synchronized start-up procedure, this" n
+    "%% function does not return until Module:init/1 has returned." n
+    "%%" n
+    (erlang-skel-separator-end 2)
+    "-spec start_link() ->" n>
+    "{ok, Pid :: pid()} |" n>
+    "ignore |" n>
+    "{error, Error :: term()}." n
+    "start_link() ->" n>
+    "gen_statem:start_link({local, ?SERVER}, ?MODULE, [], [])." n
+    n
+    (erlang-skel-double-separator-start 3)
+    "%%% gen_statem callbacks" n
+    (erlang-skel-double-separator-end 3) n
+    (erlang-skel-separator-start 2)
+    "%% @private" n
+    "%% @doc" n
+    "%% Whenever a gen_statem is started using gen_statem:start/[3,4] or" n
+    "%% gen_statem:start_link/[3,4], this function is called by the new" n
+    "%% process to initialize." n
+    (erlang-skel-separator-end 2)
+    "-spec init(Args :: term()) -> " n>
+    "{gen_statem:callback_mode()," n>
+    "State :: term(), Data :: term()} |" n>
+    "{gen_statem:callback_mode()," n>
+    "State :: term(), Data :: term()," n>
+    "[gen_statem:action()] | gen_statem:action()} |" n>
+    "ignore |" n>
+    "{stop, Reason :: term()}." n
+    "init([]) ->" n>
+    "{state_functions, state_name, #data{}}." n
+    n
+    (erlang-skel-separator-start 2)
+    "%% @private" n
+    "%% @doc" n
+    "%% If the gen_statem runs with CallbackMode =:= state_functions" n
+    "%% there should be one instance of this function for each possible" n
+    "%% state name. Whenever a gen_statem receives an event," n
+    "%% the instance of this function with the same name" n
+    "%% as the current state name StateName is called to" n
+    "%% handle the event." n
+    (erlang-skel-separator-end 2)
+    "-spec state_name(" n>
+    "gen_statem:event_type(), Msg :: term()," n>
+    "Data :: term()) ->" n>
+    "gen_statem:state_function_result(). " n
+    "state_name({call,Caller}, _Msg, Data) ->" n>
+    "{next_state, state_name, Data, [{reply,Caller,ok}]}." n
+    n
+    (erlang-skel-separator-start 2)
+    "%% @private" n
+    "%% @doc" n
+    "%% If the gen_statem runs with CallbackMode =:= handle_event_function" n
+    "%% this function is called for every event a gen_statem receives." n
+    (erlang-skel-separator-end 2)
+    "-spec handle_event(" n>
+    "gen_statem:event_type(), Msg :: term()," n>
+    "State :: term(), Data :: term()) ->" n>
+    "gen_statem:handle_event_result(). " n
+    "handle_event({call,From}, _Msg, State, Data) ->" n>
+    "{next_state, State, Data, [{reply,From,ok}]}." n
+    n
+    (erlang-skel-separator-start 2)
+    "%% @private" n
+    "%% @doc" n
+    "%% This function is called by a gen_statem when it is about to" n
+    "%% terminate. It should be the opposite of Module:init/1 and do any" n
+    "%% necessary cleaning up. When it returns, the gen_statem terminates with" n
+    "%% Reason. The return value is ignored." n
+    (erlang-skel-separator-end 2)
+    "-spec terminate(Reason :: term(), State :: term(), Data :: term()) ->" n>
+    "any()." n
+    "terminate(_Reason, _State, _Data) ->" n>
+    "void." n
+    n
+    (erlang-skel-separator-start 2)
+    "%% @private" n
+    "%% @doc" n
+    "%% Convert process state when code is changed" n
+    (erlang-skel-separator-end 2)
+    "-spec code_change(" n>
+    "OldVsn :: term() | {down,term()}," n>
+    "State :: term(), Data :: term(), Extra :: term()) ->" n>
+    "{ok, NewState :: term(), NewData :: term()}." n
+    "code_change(_OldVsn, State, Data, _Extra) ->" n>
+    "{ok, State, Data}." n
+    n
+    (erlang-skel-double-separator-start 3)
+    "%%% Internal functions" n
+    (erlang-skel-double-separator-end 3)
+    )
+  "*The template of a gen_statem.
+Please see the function `tempo-define-template'.")
+
 (defvar erlang-skel-wx-object
   '((erlang-skel-include erlang-skel-large-header)
     "-behaviour(wx_object)." n n