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!