diff -r 2d91b2107656 -r f5214da1976e progs/compile_arrays.scala
--- /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")