diff -r 71ef7d9ef635 -r d27d35a0164a progs/while-compiler-arrays/compile_arrays.sc
--- a/progs/while-compiler-arrays/compile_arrays.sc	Mon Oct 26 10:24:59 2020 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,239 +0,0 @@
-// A Small Compiler for the WHILE Language
-//
-// - this compiler contains support for "static" integer 
-//   arrays (they are mutable but cannot be re-sized)
-//
-// Call with 
-//
-// amm compile_arrays.sc
-  
-
-// the abstract syntax trees for WHILE
-
-abstract class Stmt
-abstract class AExp
-abstract class BExp 
-type Block = List[Stmt]
-
-// statements
-case object Skip extends Stmt
-case class ArrayDef(s: String, n: Int) extends Stmt            // array definition
-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             // var := exp
-case class AssignA(s: String, a1: AExp, a2: AExp) extends Stmt // arr[exp1] := exp2
-case class Write(s: String) 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, a: 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 a main method and a method for writing out an integer
-//
-// - the stack and locals are hard-coded
-//
-
-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
-    invokevirtual java/io/PrintStream/print(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
-"""
-
-
-
-// for generating new labels
-var counter = -1
-
-def Fresh(x: String) = {
-  counter += 1
-  x ++ "_" ++ counter.toString()
-}
-
-// environments for variables and indices
-type Env = Map[String, Int]
-
-// convenient string interpolations 
-// for generating instructions and labels
-
-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"
-}
-
-def compile_op(op: String) = op match {
-  case "+" => i"iadd"
-  case "-" => i"isub"
-  case "*" => i"imul"
-}
-
-// 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(op, a1, a2) => 
-    compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ compile_op(op)
-  case Ref(s, a) =>
-    i"aload ${env(s)}" ++ compile_aexp(a, 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 = env.getOrElse(x, env.keys.size)
-    (compile_aexp(a, env) ++ i"istore $index \t\t; $x", 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)} \t\t; $x" ++ 
-     i"invokestatic XXX/XXX/write(I)V", env)
-  case ArrayDef(s: String, n: Int) => {
-    val index = if (env.isDefinedAt(s)) throw new Exception("array def error") else 
-                    env.keys.size
-    (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 defined")
-    (i"aload ${env(s)}" ++
-     compile_aexp(a1, env) ++
-     compile_aexp(a2, env) ++
-     i"iastore", env)
-  } 
-}
-
-// compile a block (i.e. list of statements)
-def compile_block(bl: Block, env: Env) : (String, Env) = bl match {
-  case Nil => ("", env)
-  case s::bl => {
-    val (instrs1, env1) = compile_stmt(s, env)
-    val (instrs2, env2) = compile_block(bl, env1)
-    (instrs1 ++ instrs2, env2)
-  }
-}
-
-
-// main compile function for blocks (adds headers and proper JVM names)
-def compile(bl: Block, class_name: String) : String = {
-  val instructions = compile_block(bl, Map())._1
-  (beginning ++ instructions ++ ending).replace("XXX", class_name)
-}
-
-
-
-// contrived example involving arrays
-val array_test = 
-  List(ArrayDef("a", 10),               // array a[10]
-       ArrayDef("b", 2),                // array b[2]
-       AssignA("a", Num(0), Num(10)),   // a[0] := 10
-       Assign("x", Ref("a", Num(0))),   // x := a[0]
-       Write("x"),            
-       AssignA("b", Num(1), Num(5)),    // b[1] := 5
-       Assign("x", Ref("b", Num(1))),   // x := b[1] 
-       Write("x"))                     
-
-
-// prints out the JVM-assembly instructions for fib above
-//
-//    println(compile(array_test, "arr"))
-//
-// can be assembled by hand with 
-//
-//    java -jar jasmin.jar arr.j
-//
-// and run with
-//
-//    java arr/arr
-
-// automating the above
-import ammonite.ops._
-
-def compile_to_file(bl: Block, class_name: String) : Unit = 
-  write.over(pwd / s"$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 $class_name.j file")
-  os.proc("java", "-jar", "jasmin.jar", s"$class_name.j").call()
-  println(s"generated $class_name.class file ")
-  //println(os.proc("java", s"${class_name}/${class_name}").call().out.text())
-  os.proc("java", s"${class_name}/${class_name}").call(stdout = os.Inherit)
-  println(s"done.")
-}
-
-
-   
-@main def main() = {
-  compile_and_run(array_test, "arr")
-}
-
-