--- a/progs/comb2.scala	Sun Jul 28 17:29:53 2019 +0100
+++ b/progs/comb2.scala	Sun Jul 28 21:10:39 2019 +0100
@@ -76,6 +76,8 @@
 case class If(a: BExp, bl1: Block, bl2: Block) extends Stmt
 case class While(b: BExp, bl: Block) extends Stmt
 case class Assign(s: String, a: AExp) extends Stmt
+case class Write(s: String) extends Stmt
+
 
 case class Var(s: String) extends AExp
 case class Num(i: Int) extends AExp
@@ -84,7 +86,8 @@
 case object True extends BExp
 case object False extends BExp
 case class Bop(o: String, a1: AExp, a2: AExp) extends BExp
-
+case class And(b1: BExp, b2: BExp) extends BExp
+case class Or(b1: BExp, b2: BExp) extends BExp
 
 case object IdParser extends Parser[String, String] {
   val reg = "[a-z][a-z,0-9]*".r
@@ -95,28 +98,33 @@
 }
 
 lazy val AExp: Parser[String, AExp] = 
-  ((Te ~ "+" ~ AExp) ==> { case ((x, y), z) => Aop("+", x, z):AExp } ||
-   (Te ~ "-" ~ AExp) ==> { case ((x, y), z) => Aop("-", x, z):AExp } || Te)  
+  (Te ~ "+" ~ AExp) ==> { case ((x, y), z) => Aop("+", x, z): AExp } ||
+  (Te ~ "-" ~ AExp) ==> { case ((x, y), z) => Aop("-", x, z): AExp } || Te 
 lazy val Te: Parser[String, AExp] = 
-  (Fa ~ "*" ~ Te) ==> { case ((x, y), z) => Aop("*", x, z):AExp } || Fa
+  (Fa ~ "*" ~ Te) ==> { case ((x, y), z) => Aop("*", x, z): AExp } || 
+  (Fa ~ "/" ~ Te) ==> { case ((x, y), z) => Aop("/", x, z): AExp } || Fa  
 lazy val Fa: Parser[String, AExp] = 
-  (("(" ~ AExp ~ ")") ==> { case ((x, y), z) => y } || 
+   ("(" ~ AExp ~ ")") ==> { case ((x, y), z) => y } || 
    IdParser ==> Var || 
-   NumParser ==> Num)
+   NumParser ==> Num
 
-// boolean expressions
+// boolean expressions with some simple nesting
 lazy val BExp: Parser[String, BExp] = 
-  ((AExp ~ "=" ~ AExp) ==> { case ((x, y), z) => Bop("=", x, z):BExp } || 
-   (AExp ~ "!=" ~ AExp) ==> { case ((x, y), z) => Bop("!=", x, z):BExp } || 
-   (AExp ~ "<" ~ AExp) ==> { case ((x, y), z) => Bop("<", x, z):BExp } || 
-   (AExp ~ ">" ~ AExp) ==> { case ((x, y), z) => Bop(">", x, z):BExp } || 
-   ("true" ==> ((_) => True:BExp )) || 
-   ("false" ==> ((_) => False:BExp )) ||
-   ("(" ~ BExp ~ ")") ==> { case ((x, y), z) => y})
+   (AExp ~ "==" ~ AExp) ==> { case ((x, y), z) => Bop("==", x, z) }: Bexp || 
+   (AExp ~ "!=" ~ AExp) ==> { case ((x, y), z) => Bop("!=", x, z): BExp } || 
+   (AExp ~ "<" ~ AExp) ==> { case ((x, y), z) => Bop("<", x, z): BExp } || 
+   (AExp ~ ">" ~ AExp) ==> { case ((x, y), z) => Bop(">", x, z): BExp } ||
+   ("(" ~ BExp ~ ")" ~ "&&" ~ BExp) ==> { case ((((x, y), z), u), v) => And(y, v): BExp } ||
+   ("(" ~ BExp ~ ")" ~ "||" ~ BExp) ==> { case ((((x, y), z), u), v) => Or(y, v): BExp } ||
+   ("true" ==> ((_) => True: BExp )) || 
+   ("false" ==> ((_) => False: BExp )) ||
+   ("(" ~ BExp ~ ")") ==> { case ((x, y), z) => y}
 
+// statements
 lazy val Stmt: Parser[String, Stmt] =
   (("skip" ==> ((_) => Skip: Stmt)) ||
    (IdParser ~ ":=" ~ AExp) ==> { case ((x, y), z) => Assign(x, z): Stmt } ||
+   ("write(" ~ IdParser ~ ")") ==> { case ((x, y), z) => Write(y): Stmt } ||
    ("if" ~ BExp ~ "then" ~ Block ~ "else" ~ Block) ==>
     { case (((((x,y),z),u),v),w) => If(y, u, w): Stmt } ||
    ("while" ~ BExp ~ "do" ~ Block) ==> { case (((x, y), z), w) => While(y, w) }) 
@@ -134,7 +142,17 @@
 Block.parse_all("{x:=5;y:=8}")
 Block.parse_all("if(false)then{x:=5}else{x:=10}")
 
-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}"""
+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}""".replaceAll("\\s+", "")
 
 Block.parse_all(fib)
 
@@ -147,15 +165,18 @@
   case Aop("+", a1, a2) => eval_aexp(a1, env) + eval_aexp(a2, env)
   case Aop("-", a1, a2) => eval_aexp(a1, env) - eval_aexp(a2, env)
   case Aop("*", a1, a2) => eval_aexp(a1, env) * eval_aexp(a2, env)
+  case Aop("/", a1, a2) => eval_aexp(a1, env) / eval_aexp(a2, env)
 }
 
 def eval_bexp(b: BExp, env: Env) : Boolean = b match {
   case True => true
   case False => false
-  case Bop("=", a1, a2) => eval_aexp(a1, env) == eval_aexp(a2, env)
+  case Bop("==", a1, a2) => eval_aexp(a1, env) == eval_aexp(a2, env)
   case Bop("!=", a1, a2) => !(eval_aexp(a1, env) == eval_aexp(a2, env))
   case Bop(">", a1, a2) => eval_aexp(a1, env) > eval_aexp(a2, env)
   case Bop("<", a1, a2) => eval_aexp(a1, env) < eval_aexp(a2, env)
+  case And(b1, b2) => eval_bexp(b1, env) && eval_bexp(b2, env)
+  case Or(b1, b2) => eval_bexp(b1, env) || eval_bexp(b2, env)
 }
 
 def eval_stmt(s: Stmt, env: Env) : Env = s match {
@@ -165,6 +186,7 @@
   case While(b, bl) => 
     if (eval_bexp(b, env)) eval_stmt(While(b, bl), eval_bl(bl, env))
     else env
+  case Write(x) => { println(env(x)) ; env }  
 }
 
 def eval_bl(bl: Block, env: Env) : Env = bl match {
@@ -177,3 +199,39 @@
 // parse + evaluate fib program; then lookup what is
 // stored under the variable result 
 println(eval(Block.parse_all(fib).head)("result"))
+
+
+// more examles
+
+// calculate and print all factors bigger 
+// than 1 and smaller than n
+println("Factors")
+
+val factors =  
+   """{n := 12;
+      f := 2;
+      while (f < n / 2 + 1) do {
+        if ((n / f) * f == n) then  { write(f) } else { skip };
+        f := f + 1
+      }}""".replaceAll("\\s+", "")
+
+eval(Block.parse_all(factors).head)
+
+// calculate all prime numbers up to a number 
+println("Primes")
+
+val primes =  
+   """{end := 100;
+      n := 2;
+      while (n < end) do {
+        f := 2;
+        tmp := 0;
+        while ((f < n / 2 + 1) && (tmp == 0)) do {
+          if ((n / f) * f == n) then  { tmp := 1 } else { skip };
+          f := f + 1
+        };
+        if (tmp == 0) then { write(n) } else { skip };
+        n  := n + 1
+      }}""".replaceAll("\\s+", "")
+
+eval(Block.parse_all(primes).head)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/compile_arrays.scala	Sun Jul 28 21:10:39 2019 +0100
@@ -0,0 +1,317 @@
+// A Small Compiler for the WHILE Language with Arrays
+// (it does not use a parser and lexer)
+
+// the new parts are
+//    - declaring an array
+//    - references an array cell
+//    - assigning an array cell
+
+// the abstract syntax trees
+abstract class Stmt
+abstract class AExp
+abstract class BExp 
+type Block = List[Stmt]
+
+// statements
+case object Skip extends Stmt
+case class If(a: BExp, bl1: Block, bl2: Block) extends Stmt
+case class While(b: BExp, bl: Block) extends Stmt
+case class Assign(s: String, a: AExp) extends Stmt
+case class AssignA(s: String, a1: AExp, a2: AExp) extends Stmt
+case class Write(s: String) extends Stmt
+case class Array(s: String, n: Int) extends Stmt 
+
+// arithmetic expressions
+case class Var(s: String) extends AExp
+case class Num(i: Int) extends AExp
+case class Aop(o: String, a1: AExp, a2: AExp) extends AExp
+case class Ref(s: String, a1: AExp) extends AExp
+
+// boolean expressions
+case object True extends BExp
+case object False extends BExp
+case class Bop(o: String, a1: AExp, a2: AExp) extends BExp
+
+
+// compiler headers needed for the JVM
+// (contains an init method, as well as methods for read and write)
+val beginning = """
+.class public XXX.XXX
+.super java/lang/Object
+
+.method public <init>()V
+   aload_0
+   invokenonvirtual java/lang/Object/<init>()V
+   return
+.end method
+
+.method public static write(I)V 
+    .limit locals 1 
+    .limit stack 2 
+    getstatic java/lang/System/out Ljava/io/PrintStream; 
+    iload 0
+    invokevirtual java/io/PrintStream/println(I)V 
+    return 
+.end method
+
+.method public static main([Ljava/lang/String;)V
+   .limit locals 200
+   .limit stack 200
+
+; COMPILED CODE STARTS
+
+"""
+
+val ending = """
+; COMPILED CODE ENDS
+   return
+
+.end method
+"""
+
+// Compiler functions
+
+
+// for generating new labels
+var counter = -1
+
+def Fresh(x: String) = {
+  counter += 1
+  x ++ "_" ++ counter.toString()
+}
+
+// convenient string interpolations 
+// for instructions and labels
+import scala.language.implicitConversions
+import scala.language.reflectiveCalls
+
+implicit def sring_inters(sc: StringContext) = new {
+    def i(args: Any*): String = "   " ++ sc.s(args:_*) ++ "\n"
+    def l(args: Any*): String = sc.s(args:_*) ++ ":\n"
+}
+
+
+// environments 
+type Env = Map[String, String]
+
+// arithmetic expression compilation
+def compile_aexp(a: AExp, env : Env) : String = a match {
+  case Num(i) => i"ldc $i"
+  case Var(s) => i"iload ${env(s)}"
+  case Aop("+", a1, a2) => 
+    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"iadd"
+  case Aop("-", a1, a2) => 
+    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"isub"
+  case Aop("*", a1, a2) => 
+    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"imul"
+  case Ref(s, a1) => 
+    i"aload ${env(s)}" ++ compile_aexp(a1, env) ++ i"iaload"  
+}
+
+// boolean expression compilation
+def compile_bexp(b: BExp, env : Env, jmp: String) : String = b match {
+  case True => ""
+  case False => i"goto $jmp"
+  case Bop("=", a1, a2) => 
+    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"if_icmpne $jmp"
+  case Bop("!=", a1, a2) => 
+    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"if_icmpeq $jmp"
+  case Bop("<", a1, a2) => 
+    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ i"if_icmpge $jmp"
+}
+
+// statement compilation
+def compile_stmt(s: Stmt, env: Env) : (String, Env) = s match {
+  case Skip => ("", env)
+  case Assign(x, a) => {
+    val index = if (env.isDefinedAt(x)) env(x) else 
+                    env.keys.size.toString
+    (compile_aexp(a, env) ++ i"istore $index", env + (x -> index))
+  } 
+  case If(b, bl1, bl2) => {
+    val if_else = Fresh("If_else")
+    val if_end = Fresh("If_end")
+    val (instrs1, env1) = compile_block(bl1, env)
+    val (instrs2, env2) = compile_block(bl2, env1)
+    (compile_bexp(b, env, if_else) ++
+     instrs1 ++
+     i"goto $if_end" ++
+     l"$if_else" ++
+     instrs2 ++
+     l"$if_end", env2)
+  }
+  case While(b, bl) => {
+    val loop_begin = Fresh("Loop_begin")
+    val loop_end = Fresh("Loop_end")
+    val (instrs1, env1) = compile_block(bl, env)
+    (l"$loop_begin" ++
+     compile_bexp(b, env, loop_end) ++
+     instrs1 ++
+     i"goto $loop_begin" ++
+     l"$loop_end", env1)
+  }
+  case Write(x) => 
+    (i"iload ${env(x)}" ++ 
+     i"invokestatic XXX/XXX/write(I)V", env)
+  case Array(s, n) => {
+    val index = if (env.isDefinedAt(s)) throw new Exception("Array already defined") else 
+                    env.keys.size.toString
+    (i"ldc $n" ++
+     i"newarray int" ++
+     i"astore $index", env + (s -> index))
+  } 
+  case AssignA(s, a1, a2) => {
+    val index = if (env.isDefinedAt(s)) env(s) else 
+                    throw new Exception("Array not yet defined")
+    (i"aload $index" ++
+     compile_aexp(a1, env) ++
+     compile_aexp(a2, env) ++
+     i"iastore", env)
+  } 
+}
+
+// compilation of a block (i.e. list of instructions)
+def compile_block(bl: Block, env: Env) : (String, Env) = bl match {
+  case Nil => ("", env)
+  case s::bl => {
+    val (instrs1, env1) = compile_stmt(s, env)
+    val (instrs2, env2) = compile_block(bl, env1)
+    (instrs1 ++ instrs2, env2)
+  }
+}
+
+// main compilation function for blocks
+def compile(bl: Block, class_name: String) : String = {
+  val instructions = compile_block(bl, Map.empty)._1
+  (beginning ++ instructions.mkString ++ ending).replaceAllLiterally("XXX", class_name)
+}
+
+// compiling and running files
+//
+// JVM files can be assembled with 
+//
+//    java -jar jvm/jasmin-2.4/jasmin.jar fib.j
+//
+// and started with
+//
+//    java fib/fib
+
+
+
+import scala.util._
+import scala.sys.process._
+import scala.io
+
+def compile_tofile(bl: Block, class_name: String) = {
+  val output = compile(bl, class_name)
+  val fw = new java.io.FileWriter(class_name + ".j") 
+  fw.write(output) 
+  fw.close()
+}
+
+def compile_all(bl: Block, class_name: String) : Unit = {
+  compile_tofile(bl, class_name)
+  println("compiled ")
+  val test = ("java -jar jvm/jasmin-2.4/jasmin.jar " + class_name + ".j").!!
+  println("assembled ")
+}
+
+def time_needed[T](i: Int, code: => T) = {
+  val start = System.nanoTime()
+  for (j <- 1 to i) code
+  val end = System.nanoTime()
+  (end - start)/(i * 1.0e9)
+}
+
+
+def compile_run(bl: Block, class_name: String) : Unit = {
+  println("Start compilation")
+  compile_all(bl, class_name)
+  println("running")
+  println("Time: " + time_needed(1, ("java " + class_name + "/" + class_name).!))
+}
+
+
+// BF Part
+
+// simple instructions
+def instr(c: Char) : String = c match {
+  case '>' => "ptr := ptr + 1;"
+  case '<' => "ptr := ptr - 1;"
+  case '+' => "field[ptr] := field[ptr] + 1;"
+  case '-' => "field[ptr] := field[ptr] - 1;"
+  case '.' => "x := field[ptr]; write x;"
+  case '['  => "while (field[ptr] != 0) do {"
+  case ']'  => "skip};"
+  case _ => ""
+}
+
+def instrs(prog: String) : String =
+  prog.toList.map(instr).mkString
+
+
+// compound instructions
+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 '+' => s"field[ptr] := field[ptr] + $n;"
+  case '-' => s"field[ptr] := field[ptr] - $n;"
+  case '.' => s"x := field[ptr]; write x;" 
+  case '['  => s"while (field[ptr] != 0) do {" * n 
+  case ']'  => s"skip};" * n
+  case _ => ""
+}
+
+def instrs2(prog: String) : String =
+  spl(prog).map{ case (c, n) => instr2(c, n) }.mkString
+
+
+def bf_str(prog: String) : String = {
+  "\n" ++
+  //"new field[30000];\n" ++
+  "ptr := 15000;" ++
+  instrs2(prog) ++
+  "skip"
+}
+
+def bf_run(bfprog: String, name: String) = {
+  println("BF processing start")
+  val bf_string = bf_str(bfprog).replaceAll("\\s", "")
+  println(s"BF parsing start (string length ${bf_string.length})")
+  val bf_prog = Stmts.parse_all(bf_string).toList.head
+  println("BF Compile start")
+  compile_run(Array("field", 30000) :: bf_prog, name)
+}
+
+
+
+val bf1 = """++++++++[>+>++++<<-]>++>>+<[-[>>+<<-]+>>]>+[-<<<[
+      ->[+[-]+>++>>>-<<]<[<]>>++++++[<<+++++>>-]+<<++.[-]<<
+      ]>.>+[>>]>+]"""
+
+bf_run(bf1, "sier")
+
+bf_run("""++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++
+       ..+++.>>.<-.<.+++.------.--------.>>+.>++.""", "hello")
+
+bf_run("""+++++++++++
+      >+>>>>++++++++++++++++++++++++++++++++++++++++++++
+      >++++++++++++++++++++++++++++++++<<<<<<[>[>>>>>>+>
+      +<<<<<<<-]>>>>>>>[<<<<<<<+>>>>>>>-]<[>++++++++++[-
+      <-[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]>[<<[>>>+<<<
+      -]>>[-]]<<]>>>[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]
+      >[<<+>>[-]]<<<<<<<]>>>>>[+++++++++++++++++++++++++
+      +++++++++++++++++++++++.[-]]++++++++++<[->-<]>++++
+      ++++++++++++++++++++++++++++++++++++++++++++.[-]<<
+      <<<<<<<<<<[>>>+>+<<<<-]>>>>[<<<<+>>>>-]<-[>>.>.<<<
+      [-]]<<[>>+>+<<<-]>>>[<<<+>>>-]<<[<+>-]>[<+>-]<<<-]""", "fibs")