Nasal-Interpreter/test/turingmachine.nas

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import("lib.nas");
var table=[
['q0','0','1','R','q1'],
['q1','1','1','R','q1'],
['q1','0','0','S','q2'],
['q2','0','1','R','q3'],
['q3',nil,nil,'S','q3']
];
var prt=func(state,pointer,paper,act=nil){
print(state,':',pointer,':',act!=nil?act:'','\n\t');
var s='';
foreach(var i;paper)
s~=i;
s~='\n\t';
for(var i=0;i<pointer;i+=1)
for(var j=0;j<size(paper[i]);j+=1)
s~=' ';
print(s,'^\n');
}
var run=func(table,node,start,stop){
var paper=['0','1','1','1','0','1','0','a'];
var pointer=0;
foreach(var action;table){
if(!contains(node,action[0]))
node[action[0]]=nil;
if(!contains(node,action[4]))
node[action[4]]=nil;
}
print("nodes: ",keys(node),'\n');
if(!contains(node,start))
die(start~" is not a valid node");
if(!contains(node,stop))
die(stop~" is not a valid node");
var state=start;
prt(state,pointer,paper);
while(state!=stop){
foreach(var action;table)
if(action[0]==state and (action[1]==paper[pointer] or action[1]==' ')){
paper[pointer]=action[2]==nil?paper[pointer]:action[2];
if(action[3]=='L') pointer-=1;
elsif(action[3]=='R') pointer+=1;
elsif(action[3]!='S') die("invalid action <"~action[3]~'>');
state=action[4];
break;
}
prt(state,pointer,paper,action);
}
}
run(table,{},'q0','q3');