a better k parser for joy

stevan apter — 2000-06-03 23:43:41

my original joy parser was a horror.  i can't imagine what i was thinking

when i wrote that code.  in any case, those who are using my interpreter

can replace that block with this one:



\d Parse

N:"_.0123456789"

A:"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

O:("&|~+-*/%=<>";`and`or`not`plus`minus`mul`idiv`div`eq`lt`gt)



in:{r:(x;());while[#*r;r:i.next . r];r 1}

i.next:{:[" "=c:*x;i.blank;"["=c;i.list;"\""=c;i.string;c _in*O;i.oper;c _in N;i.num;i.name][x;y]}

i.blank:{n:(x=" ")?0;(n _ x;y)}

i.list:{n:(=/+\'x=/:"[]")?1;((n+1)_ x;y,,in 1_ n#x)}

i.string:{n:(t:1_ x)?"\"";((n+1)_ t;y,,n#t)}

i.num:{n:+/&\x _lin N;(n _ x;y,._ssr[n#x;"_";"-"])}

i.oper:{(1_ x;y,,O[1;O[0]?*x])}

i.name:{n:+/&\x _lin A,N;(n _ x;y,`$n#x)}



out:{(1_,/(" ",o.term@)'|x),"\n"}

o.term:{:[-3=t:4:x;"\"",x,"\"";1>t;o.list@_f'x;t=3;"'",x;t=5;_f(+($!x;x[]);`dict);$(O[0],,x)O[1]?x]}

o.list:{"[",(1_,/" ",'$x),"]"}



\d ^