Finite state machine: Difference between revisions
Include the state in the prompt
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Refunding money
Machine ready: (d)eposit, or (q)uit?q
</pre>
=={{header|ALGOL 68}}==
<syntaxhighlight lang="algol68">
BEGIN # finite state machine #
# mode representing a state in the FSM #
MODE FSMSTATE = STRUCT( INT state # code for the state #
, PROC INT next state # routine to change state #
);
# executes the FSM defined by states, starting from the initial state #
# and terminating when the exit state is reached #
PROC run fsm = ( []FSMSTATE states, INT initial state, exit state )VOID:
BEGIN
INT state := initial state;
WHILE state /= exit state DO
BOOL found := FALSE;
FOR s pos FROM LWB states TO UPB states WHILE NOT found DO
IF found := state OF states[ s pos ] = state THEN
state := next state OF states[ s pos ]
FI
OD;
IF NOT found THEN
# in an invalid state - restart #
print( ( "(resetting)", newline ) );
state := initial state
FI
OD
END # run fsm # ;
BEGIN # test FSM #
# possible states #
INT exit = 0, ready = 1, waiting = 2, dispense = 3, refunding = 4;
# prompts the user for a single character code and returns it #
# the user is re-prompted until they enter one of the characters in #
# answers #
PROC get code = ( STRING prompt, answers )CHAR:
BEGIN
CHAR response;
WHILE print( ( prompt, ": " ) );
STRING answer;
read( ( answer, newline ) );
response := IF answer = "" THEN REPR 0 ELSE answer[ LWB answer ] FI;
IF response >= "a" AND response <= "z" THEN
# convert lowercase response to upper #
response := REPR ( ABS response + ( ABS "A" - ABS "a" ) )
FI;
NOT char in string( response, NIL, answers )
DO SKIP OD;
response
END # get code # ;
run fsm( ( ( ready
, INT: IF "Q" = get code( "Ready : Enter D to deposit, Q to Quit", "DQ" )
THEN exit
ELSE waiting
FI
)
, ( waiting
, INT: IF "S" = get code( "Waiting : Enter S to Select, R to Refund", "SR" )
THEN dispense
ELSE refunding
FI
)
, ( dispense
, INT: BEGIN get code( "Dispensing: Remove your product and Enter R", "R" );
ready
END
)
, ( refunding
, INT: BEGIN print( ( "Refunding", newline ) ); ready END
)
)
, ready
, exit
)
END
END
</syntaxhighlight>
{{out}}
<pre>
Ready : Enter D to deposit, Q to Quit: d
Waiting : Enter S to Select, R to Refund: s
Dispensing: Remove your product and Enter R: r
Ready : Enter D to deposit, Q to Quit: d
Waiting : Enter S to Select, R to Refund: r
Refunding
Ready : Enter D to deposit, Q to Quit: q
</pre>
Line 2,634 ⟶ 2,725:
{{trans|Kotlin}}
{{libheader|Wren-str}}
<syntaxhighlight lang="
import "io" for Stdin, Stdout
Line 2,705 ⟶ 2,796:
(D)ispense or (Q)uit : q
OK, quitting
</pre>
=={{header|XPL0}}==
<syntaxhighlight lang "XPL0">int State, Trans, Table, Msg;
def \State\ Ready, Waiting, Dispense, Refunding, Exit;
def \Trans\ Deposit, Select, Refund, Collect, Quit; \State:
[Table:=[[Waiting, Ready, Ready, Ready, Exit], \Ready
[Waiting, Dispense, Refunding, Waiting, Waiting], \Waiting
[Dispense, Dispense, Dispense, Ready, Dispense], \Dispense
[Ready, Ready, Ready, Ready, Ready], \Refunding
[Exit, Exit, Exit, Exit, Exit]]; \Exit
State:= Ready;
loop [Msg:= ["Ready, choose (D)eposit or (Q)uit: ",
"Waiting, choose (S)elect or (R)efund: ",
"Dispensing, please (C)ollect product: ",
"Refunding, please collect refund.",
"Shutting down."];
Text(0, Msg(State));
case State of
Exit: quit;
Refunding: Trans:= Refund \implicit transition
other case ChIn(1) of \explicit transitions
^D,^d: Trans:= Deposit;
^S,^s: Trans:= Select;
^R,^r: Trans:= Refund;
^C,^c: Trans:= Collect;
^Q,^q: Trans:= Quit
other []; \illegal entries don't change state
CrLf(0);
State:= Table(State, Trans);
];
CrLf(0);
]</syntaxhighlight>
{{out}}
<pre>
Ready, choose (D)eposit or (Q)uit: D
Waiting, choose (S)elect or (R)efund: S
Dispensing, please (C)ollect product: C
Ready, choose (D)eposit or (Q)uit: D
Waiting, choose (S)elect or (R)efund: R
Refunding, please collect refund.
Ready, choose (D)eposit or (Q)uit: Q
Shutting down.
</pre>
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