1 /****************************************************************************

     2 **

     3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

     4 ** All rights reserved.

     5 ** Contact: Nokia Corporation (qt-info@nokia.com)

     6 **

     7 ** This file is part of the documentation of the Qt Toolkit.

     8 **

     9 ** $QT_BEGIN_LICENSE:LGPL$

    10 ** No Commercial Usage

    11 ** This file contains pre-release code and may not be distributed.

    12 ** You may use this file in accordance with the terms and conditions

    13 ** contained in the Technology Preview License Agreement accompanying

    14 ** this package.

    15 **

    16 ** GNU Lesser General Public License Usage

    17 ** Alternatively, this file may be used under the terms of the GNU Lesser

    18 ** General Public License version 2.1 as published by the Free Software

    19 ** Foundation and appearing in the file LICENSE.LGPL included in the

    20 ** packaging of this file.  Please review the following information to

    21 ** ensure the GNU Lesser General Public License version 2.1 requirements

    22 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.

    23 **

    24 ** In addition, as a special exception, Nokia gives you certain additional

    25 ** rights.  These rights are described in the Nokia Qt LGPL Exception

    26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.

    27 **

    28 ** If you have questions regarding the use of this file, please contact

    29 ** Nokia at qt-info@nokia.com.

    30 **

    31 **

    32 **

    33 **

    34 **

    35 **

    36 **

    37 **

    38 ** $QT_END_LICENSE$

    39 **

    40 ****************************************************************************/

    41 

    42 /*!

    43     \example statemachine/factorial

    44     \title Factorial States Example

    45 

    46     The Factorial States example shows how to use \l{The State Machine

    47     Framework} to calculate the factorial of an integer.

    48 

    49     The statechart for calculating the factorial looks as follows:

    50 

    51     \img factorial-example.png

    52     \omit

    53     \caption This is a caption

    54     \endomit

    55 

    56     In other words, the state machine calculates the factorial of 6 and prints

    57     the result.

    58 

    59     \snippet examples/statemachine/factorial/main.cpp 0

    60 

    61     The Factorial class is used to hold the data of the computation, \c x and

    62     \c fac. It also provides a signal that's emitted whenever the value of \c

    63     x changes.

    64 

    65     \snippet examples/statemachine/factorial/main.cpp 1

    66 

    67     The FactorialLoopTransition class implements the guard (\c x > 1) and

    68     calculations (\c fac = \c x * \c fac; \c x = \c x - 1) of the factorial

    69     loop.

    70 

    71     \snippet examples/statemachine/factorial/main.cpp 2

    72 

    73     The FactorialDoneTransition class implements the guard (\c x <= 1) that

    74     terminates the factorial computation. It also prints the final result to

    75     standard output.

    76 

    77     \snippet examples/statemachine/factorial/main.cpp 3

    78 

    79     The application's main() function first creates the application object, a

    80     Factorial object and a state machine.

    81 

    82     \snippet examples/statemachine/factorial/main.cpp 4

    83 

    84     The \c compute state is created, and the initial values of \c x and \c fac

    85     are defined. A FactorialLoopTransition object is created and added to the

    86     state.

    87 

    88     \snippet examples/statemachine/factorial/main.cpp 5

    89 

    90     A final state, \c done, is created, and a FactorialDoneTransition object

    91     is created with \c done as its target state. The transition is then added

    92     to the \c compute state.

    93 

    94     \snippet examples/statemachine/factorial/main.cpp 6

    95 

    96     The machine's initial state is set to be the \c compute state. We connect

    97     the QStateMachine::finished() signal to the QCoreApplication::quit() slot,

    98     so the application will quit when the state machine's work is

    99     done. Finally, the state machine is started, and the application's event

   100     loop is entered.

   101 

   102  */