diff -r 31a9f89776a3 -r d47041b23498 progs/while-arrays/compile_bfc.sc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/while-arrays/compile_bfc.sc	Mon Oct 26 10:27:01 2020 +0000
@@ -0,0 +1,310 @@
+// Some more interesting testcases for the 
+// WHILE compiler with arrays, it includes: 
+//
+//  - a small parser for WHILE programs
+//
+//  - transpiles BF programs into WHILE programs
+//    and then compiles and runs them
+//
+//  - the power-example is the Mandelbrot set:
+//       
+//       * 65k for the transpiled WHILE program 
+//       * parsing uses around 30 secs using fastparse
+//       * the jasmin assembly file is 236k
+//       * the resulting Java program takes about 20 secs 
+//
+// Call with (X being 0,1,..,4)
+//
+//  amm compile_bfc.sc all
+//  amm compile_bfc.sc bfcX
+
+
+// load the compiler
+import $file.compile_arrays
+import compile_arrays._ 
+
+def time_needed[T](i: Int, code: => T) = {
+  val start = System.nanoTime()
+  for (j <- 2 to i) code
+  val result = code
+  val end = System.nanoTime()
+  ((end - start) / (i * 1.0e9), result)
+}
+
+// for BF we have to change the write library-function,
+// because in BF integers are written out as characters
+val beginning = """
+.class public XXX.XXX
+.super java/lang/Object
+
+.method public static write(I)V 
+    .limit locals 1 
+    .limit stack 2 
+    getstatic java/lang/System/out Ljava/io/PrintStream; 
+    iload 0
+    i2c                                           ; Int => Char
+    invokevirtual java/io/PrintStream/print(C)V   ; println(I)V => print(C)V    
+    return 
+.end method
+
+.method public static main([Ljava/lang/String;)V
+   .limit locals 200
+   .limit stack 200
+
+; COMPILED CODE STARTS   
+
+"""
+
+
+// modified main compilation function for blocks
+def compile(bl: Block, class_name: String) : String = {
+  val instructions = compile_block(bl, Map())._1
+  (beginning ++ instructions ++ ending).replace("XXX", class_name)
+}
+
+// automating the above
+import ammonite.ops._
+
+def compile_to_file(bl: Block, class_name: String) : Unit = 
+  write.over(pwd / s"$class_name.j", compile(bl, class_name))  
+
+def compile_and_run(bl: Block, class_name: String) : Unit = {
+  println(s"Start of compilation")
+  compile_to_file(bl, class_name)
+  println(s"generated $class_name.j file")
+  val (jasmin_time, _) = 
+    time_needed(1, os.proc("java", "-jar", "jasmin.jar", s"$class_name.j").call())
+  println(s"generated $class_name.class file (in $jasmin_time secs).")
+  val (running_time, output) = 
+    time_needed(1, os.proc("java", s"${class_name}/${class_name}").call().out.text())
+  println(output)
+  println(s"done (in $running_time secs).")
+}
+
+
+//=====================================
+// Grammar Rules for WHILE with arrays
+//=====================================
+
+import fastparse._
+import MultiLineWhitespace._
+
+def lowercase [_ : P] = P( CharIn("a-z") )
+def uppercase[_ : P]  = P( CharIn("A-Z") )
+def letter[_ : P]     = P( lowercase | uppercase )
+def digit [_ : P]     = P( CharIn("0-9") )
+
+def Number[_ : P]: P[Int] =  P( digit.rep(1) ).!.map(_.toInt)
+def Ident[_ : P]: P[String] = P( letter ~ (letter | digit | "_").rep ).!
+
+// arithmetic expressions
+def AExp[_ : P]: P[AExp] = 
+  P(  P(Te ~ "+" ~ AExp).map{ case (l, r) => Aop("+", l, r)} 
+    | P(Te ~ "-" ~ AExp).map{ case (l, r) => Aop("-", l, r)}
+    | Te )
+def Te[_ : P]: P[AExp] = 
+  P(  P(Fa ~ "*" ~ Te).map{ case (l, r) => Aop("*", l, r)} 
+    | Fa )   
+def Fa[_ : P]: P[AExp] = 
+  P( "(" ~ AExp ~ ")" 
+     | P (Ident ~ "[" ~ AExp ~ "]").map{Ref.tupled}
+     | P(Number).map{Num} 
+     | P(Ident).map{Var} )
+
+// boolean expressions
+def BExp[_ : P]: P[BExp] = 
+  P(  P(AExp ~ "=" ~ AExp).map{ case (x, z) => Bop("=", x, z)} 
+    | P(AExp ~ "!=" ~ AExp).map{ case (x, z) => Bop("!=", x, z)}  
+    | P(AExp ~ "<" ~ AExp).map{ case (x, z) => Bop("<", x, z)}  
+    | P(AExp ~ ">" ~ AExp).map{ case (x, z) => Bop("<", z, x)}  
+    | P("true").map{ _ => True} 
+    | P("false").map{ _ => False} 
+    | "(" ~ BExp ~ ")" )
+
+// statements and blocks
+def Stmt[_ : P]: P[Stmt] =
+  P(  P("skip").map( _ => Skip) 
+    | P(Ident ~ ":=" ~ AExp).map{Assign.tupled} 
+    | P(Ident ~ "[" ~ AExp ~ "]" ~ ":=" ~ AExp).map{AssignA.tupled} 
+    | P("if" ~ BExp ~ "then" ~ Block ~ "else" ~ Block).map{If.tupled} 
+    | P("while" ~ BExp ~ "do" ~ Block).map{While.tupled} 
+    | P("new(" ~ Ident ~ "[" ~ Number ~ "])").map{ArrayDef.tupled} 
+    | P("write(" ~ Ident ~ ")").map{Write} ) 
+
+def Stmts[_ : P]: P[Block] =
+  P(  P(Stmt ~ ";" ~ Stmts).map{ case (x, z) => x :: z } 
+    | P(Stmt).map{s => List(s)} ) 
+
+def Block[_ : P]: P[Block] =
+  P(  "{" ~ Stmts ~ "}" 
+    | P(Stmt).map(s => List(s)) )
+
+// some test cases for the parser
+
+//println(fastparse.parse("(1 + (2 + 5)) + 4", AExp(_)).get)
+//println(fastparse.parse("1 + 2 + 3 + 45", AExp(_)))
+//println(fastparse.parse("1 + 2 * 3", AExp(_)))
+//println(fastparse.parse("x + 2 * 3", AExp(_)))
+//println(fastparse.parse("x2 := 5 + a", Stmts(_)))
+//println(fastparse.parse("x2 := 5 + a[3+a]", Stmts(_)))
+//println(fastparse.parse("a[x2+3] := 5 + a[3+a]", Stmts(_)))
+//println(fastparse.parse("{x := 5; y := 8}", Block(_)))
+//println(fastparse.parse("if (false) then {x := 5} else {x := 10}", Block(_)))
+
+val fib = 
+ """n := 10;
+    minus1 := 0;
+    minus2 := 1;
+    temp:=0;
+    while (n > 0) do {
+      temp := minus2; 
+      minus2 := minus1 + minus2;
+      minus1 := temp;
+      n := n - 1};
+    result := minus2;
+    write(result)
+   """
+
+//println(fastparse.parse(fib, Stmts(_)).get.value)
+
+
+
+//======================================
+// BF transpiler into WHILE with arrays
+//======================================
+
+// simple BF instructions translation
+def instr(c: Char) : String = c match {
+  case '>' => "ptr := ptr + 1;"
+  case '<' => "ptr := ptr - 1;"
+  case '+' => "mem[ptr] := mem[ptr] + 1;"
+  case '-' => "mem[ptr] := mem[ptr] - 1;"
+  case '.' => "x := mem[ptr]; write x;"
+  //case ',' => "XXX" // "ptr = getchar();\n"
+  case '['  => "while (mem[ptr] != 0) do {"
+  case ']'  => "skip};"
+  case _ => ""
+}
+
+def instrs(prog: String) : String =
+  prog.toList.map(instr).mkString
+
+
+// Note: Unfortunately, the transpiled mandelbrot.bf program 
+// is so large that it does not fit inside the limitations of 
+// what the JVM imposes on methods (only 64K of instructions).
+// Therefore some optimisations are first applied to 
+// BF programs before WHILE programs are created. The
+// optimisations are 
+//  
+//  - replacing BF-loops of the form [-] with a new 0-instruction 
+//  - combining single increment/decrement instructions
+//
+// The size of the resulting .j-file is 270K.
+
+
+def splice(cs: List[Char], acc: List[(Char, Int)]) : List[(Char, Int)] = (cs, acc) match {
+  case (Nil, acc) => acc
+  case (c :: cs, Nil) => splice(cs, List((c, 1)))
+  case (c :: cs, (d, n) :: acc) => 
+    if (c == d) splice(cs, (c, n + 1) :: acc)
+    else splice(cs, (c, 1) :: (d, n) :: acc)
+}
+
+def spl(s: String) = splice(s.toList, Nil).reverse
+
+def instr2(c: Char, n: Int) : String = c match {
+  case '>' => s"ptr := ptr + $n;"
+  case '<' => s"ptr := ptr - $n;"
+  case '0' => s"mem[ptr] := 0;"
+  case '+' => s"mem[ptr] := mem[ptr] + $n;"
+  case '-' => s"mem[ptr] := mem[ptr] - $n;"
+  case '.' => s"x := mem[ptr]; write(x);" 
+  case '['  => "while (mem[ptr] != 0) do {" * n 
+  case ']'  => "skip};" * n
+  case _ => ""
+}
+
+def instrs2(prog: String) : String =
+  spl(prog.replaceAll("""\[-\]""", "0")).map{ case (c, n) => instr2(c, n) }.mkString
+
+// adding the "header" to the BF program
+def bf_str(prog: String) : String = {
+  "new(mem[30000]);" ++
+  "ptr := 15000;" ++
+  instrs2(prog) ++
+  "skip"
+}
+
+
+def bf_run(prog: String, name: String) = {
+  println(s"BF pre-processing of $name")
+  val bf_string = bf_str(prog)
+  println(s"BF parsing (program length ${bf_string.length} characters)")
+  val (time, bf_prog) = 
+    time_needed(1, fastparse.parse(bf_string, Stmts(_)).get.value)
+  println(s"BF generated WHILE program (needed $time secs for parsing)")
+  compile_and_run(bf_prog, name)
+}
+
+// a benchmark program (counts down from 'Z' to 'A')
+@doc(" Benchmark 'Z' to 'A'.")
+@main
+def bfc0() = bf_run(read(pwd / "benchmark.bf"), "bench")
+
+
+@doc(" Sierpinski triangle.")
+@main
+def bfc1() = bf_run(read(pwd / "sierpinski.bf"), "sier")
+
+// Hello World
+val bf2 = """++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]
+      >>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++."""
+
+@doc(" Hello world.")
+@main
+def bfc2() = bf_run(bf2, "hello")
+
+// Fibonacci 
+val bf3 = """+++++++++++
+      >+>>>>++++++++++++++++++++++++++++++++++++++++++++
+      >++++++++++++++++++++++++++++++++<<<<<<[>[>>>>>>+>
+      +<<<<<<<-]>>>>>>>[<<<<<<<+>>>>>>>-]<[>++++++++++[-
+      <-[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]>[<<[>>>+<<<
+      -]>>[-]]<<]>>>[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]
+      >[<<+>>[-]]<<<<<<<]>>>>>[+++++++++++++++++++++++++
+      +++++++++++++++++++++++.[-]]++++++++++<[->-<]>++++
+      ++++++++++++++++++++++++++++++++++++++++++++.[-]<<
+      <<<<<<<<<<[>>>+>+<<<<-]>>>>[<<<<+>>>>-]<-[>>.>.<<<
+      [-]]<<[>>+>+<<<-]>>>[<<<+>>>-]<<[<+>-]>[<+>-]<<<-]
+      [-]++++++++++."""
+
+@doc(" Fibonacci numbers.")
+@main
+def bfc3() = bf_run(bf3, "fibs")
+
+// Mandelbrot Set
+//----------------
+//
+// Note: Parsing of the generated WHILE program (around 60K in size)
+// takes approximately 10 minutes to parse with our parser combinators,
+// and approximately 30 seconds with Ammonite's fastparse.
+
+@doc(" Mandelbrot set.")
+@main
+def bfc4() = bf_run(read(pwd / "mandelbrot.bf"), "mandelbrot")
+
+
+// this unfortunately hits the capacity of the JVM, even with optimisations
+//@doc(" Coolatz serries up to 30.")
+//@main
+//def bfc5() = bf_run(read(pwd / "collatz.bf"), "coll")
+
+
+//
+@doc(" All benchmarks.")
+@main
+def all() = { bfc0(); bfc1(); bfc2(); bfc3(); bfc4() } 
+
+
+