Execute Brain****/Elena
<lang elena>import system'collections. import system'routines. import system'dynamic.
import extensions. import extensions'scripting.
class BFTape {
object theArray. object thePointer. object theBrackets. constructor new:aLength [ theArray := Array new:aLength; populate(:n) [ Integer new:0 ]. thePointer := Integer new:0. theBrackets := Stack new. ] append [ theArray[thePointer] append:1. ] reduce [ theArray[thePointer] reduce:1. ] next [ thePointer append:1. ] previous [ thePointer reduce:1. ] push : bookmark [ theBrackets push:bookmark. ] pop => theBrackets. input [ theArray[thePointer] := console readChar; toInt. ] output [ console write(theArray[thePointer] toChar). ] check = theArray[thePointer] != 0.
}
const bf_program = "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.".
program = [
console writeLine:bf_program. var program := scriptEngine load path:"rules.es"; eval:bf_program. program eval:(BFTape new:1024).
].</lang> The grammar: <lang elena>[[
#grammar transform #grammar cf
#define start ::= <= ( > += " 2" += " %""system'dynamic'tapeOp.tape_var[]""" => commands <= " *" "system'dynamic'Tape" "=" # ) =>;
#define commands ::= command commands; #define commands ::= comment commands; #define commands ::= $eof;
#define command ::= <= += " %""output[0]"" " => "."; #define command ::= <= += " %""input[0]"" " => ","; #define command ::= <= += " %""previous[0]"" " => "<"; #define command ::= <= += " %""next[0]"" " => ">"; #define command ::= <= += " %""append[0]"" " => "+"; #define command ::= <= += " %""reduce[0]"" " => "-"; #define command ::= <= += " -2" += " %""system'dynamic'tapeOp.tape_ptr[]"" " += " 1" += " %""system'dynamic'tapeOp.tape_stack[]"" " += "%""push[1]"" " => "["; #define command ::= <= += " 0" += " %""system'dynamic'tapeOp.tape_stack[]"" " += " %""check[0]"" " += " 1" += " %""system'dynamic'tapeOp.tape_stack[]"" " += " %""pop[0]"" " += " %""system'dynamic'tapeOp.tape_jumpif[]"" " => "]";
#define comment ::= " " comments; #define comment ::= "'" comments; #define comment ::= "!" comments; #define comment ::= $eol;
#define comments ::= $chr comments; #define comments ::= $eps;
#mode symbolic;
]]</lang>
- Output:
ELENA VM 3.2.15 (C)2005-2017 by Alex Rakov Initializing... Debug mode... Done... ++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>. Hello World!