1 // A Transpiler for the Brainf*** language

     2 //=========================================

     3 

     4 import io.Source

     5 import scala.util._

     6 

     7 

     8 // loding a bf-file 

     9 def load_bff(name: String) : String = 

    10   Try(Source.fromFile(name)("ISO-8859-1").mkString).getOrElse("")

    11 

    12 

    13 // simple instructions

    14 def instr(c: Char) : String = c match {

    15   case '>' => "ptr++;"

    16   case '<' => "ptr--;"

    17   case '+' => "(*ptr)++;"

    18   case '-' => "(*ptr)--;"

    19   case '.' => "putchar(*ptr);"

    20   case ',' => "*ptr = getchar();\n"

    21   case '['  => "while(*ptr){"

    22   case ']'  => "}"

    23   case _ => ""

    24 }

    25 

    26 def instrs(prog: String) : String =

    27   prog.toList.map(instr(_)).mkString

    28 

    29 

    30 def compile_str(prog: String) : String = {

    31   "#include <string.h>\n" ++

    32   "#include <stdio.h>\n" ++

    33   "char field[30000];\n" ++

    34   "char *ptr = &field[15000];" ++

    35   "int main()\n{\n" ++

    36   "memset(field, '\\0', 30000);\n" ++

    37   instrs(prog) ++

    38   "\n return 0;\n}"

    39 }

    40 

    41 def compile(name: String, prog: String) = {

    42   val fw = new java.io.FileWriter(name + ".c") 

    43   val is = compile_str(prog)

    44   //println(is)

    45   fw.write(is) 

    46   fw.close()

    47 }

    48 

    49 // running the c-compiler over the transpiled

    50 // BF program and running the result

    51 import sys.process._

    52 

    53 def compile_run(prog: String) = {

    54   compile("tmp", prog)

    55   "gcc -O3 -o tmp tmp.c".!

    56   "./tmp".!

    57   ()

    58 }

    59 

    60 def time_needed[T](n: Int, code: => T) = {

    61   val start = System.nanoTime()

    62   for (i <- 0 until n) code

    63   val end = System.nanoTime()

    64   (end - start)/(n * 1.0e9)

    65 }

    66 

    67 // the mandelbrot program

    68 val b0 = load_bff("mandelbrot.bf")

    69 

    70 println(s"${time_needed(1, compile_run(b0))} secs")

    71 

    72 

    73 

    74 // a benchmark program (counts down from 'Z' to 'A')

    75 val b1 = """>++[<+++++++++++++>-]<[[>+>+<<-]>[<+>-]++++++++

    76             [>++++++++<-]>.[-]<<>++++++++++[>++++++++++[>++

    77             ++++++++[>++++++++++[>++++++++++[>++++++++++[>+

    78             +++++++++[-]<-]<-]<-]<-]<-]<-]<-]++++++++++."""

    79 

    80 println(s"${time_needed(1, compile_run(b1))} secs")

    81 

    82 

    83 

    84