Anonymous user
Finite state machine: Difference between revisions
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=={{header|zkl}}==
A lame FSM, we just convert text to a [hopefully valid] zkl program, compile and run it.
<lang zkl></lang>▼
<lang zkl></lang>▼
If we need true state to state hops, we could use tail recursion (another name for goto).
<lang zkl></lang>▼
<lang zkl>class FSM{ // our Finite State Machine
var bank=0, item=Void;
fcn deposit(coin){ bank=coin }
fcn select(item){
if(bank){ bank=0; self.item=item; }
else print("Depost coin, then select ")
}
fcn take { if(item) item=Void; else print("Select first "); }
fcn refund { coin:=bank; bank=0; return(coin) }
// couple of wrappers to state changes
fcn state{ println("Bank(%4d), Item(%s)".fmt(bank,item)) }
fcn act(f){ print("%-10s-->".fmt(f.name)); f(); state(); }
}
Vault.add(FSM); // put class FSM where I can find it</lang>
<lang zkl>fcn run(program){ // convert text to FSM instructions and run them
program=program.replace("(",".fp("); // deposit(10)-->deposit.fp(10)
a,b,p := 0,0,Sink("class P(FSM){ state(); ");
while(Void!=(b=program.find(";",a)))
{ p.write("act(",program[a,b-a],");"); a=b + 1; }
program=p.write(program[a,*],"}").close();
// println(program); // WTH did I just do?
Compiler.Compiler.compileText(program)(); // compile and run our little FSM
<lang zkl>run("select(); take(); deposit(10); select(\"snickers\"); take();");</lang>
The above is converted to:
state();
act(select.fp());
act( take.fp());
act( deposit.fp(10));
act( select.fp("snickers"));
act( take.fp());
The .fp() is function application (ie deferred execution) so I can extract the
function name and print it.
{{out}}
<pre>
Bank( 0), Item(Void)
select -->Depost coin, then select Bank( 0), Item(Void)
take -->Select first Bank( 0), Item(Void)
deposit -->Bank( 10), Item(Void)
select -->Bank( 0), Item(snickers)
take -->Bank( 0), Item(Void)
</pre>
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