progs/fun/fun-bare.scala
changeset 735 fc2e3609d5e5
parent 734 5d860ff01938
child 736 d3e477fe6c66
--- a/progs/fun/fun-bare.scala	Sat Jul 04 22:12:18 2020 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,187 +0,0 @@
-// A Small Compiler for a Simple Functional Language
-// (it does not include a parser and lexer)
-
-// abstract syntax trees
-abstract class Exp
-abstract class BExp 
-abstract class Decl
-
-// functions and declarations
-case class Def(name: String, args: List[String], body: Exp) extends Decl
-case class Main(e: Exp) extends Decl
-
-// expressions
-case class Call(name: String, args: List[Exp]) extends Exp
-case class If(a: BExp, e1: Exp, e2: Exp) extends Exp
-case class Write(e: Exp) extends Exp
-case class Var(s: String) extends Exp
-case class Num(i: Int) extends Exp
-case class Aop(o: String, a1: Exp, a2: Exp) extends Exp
-case class Sequ(e1: Exp, e2: Exp) extends Exp
-
-// boolean expressions
-case class Bop(o: String, a1: Exp, a2: Exp) extends BExp
-
-// calculating the maximal needed stack size
-def max_stack_exp(e: Exp): Int = e match {
-  case Call(_, args) => args.map(max_stack_exp).sum
-  case If(a, e1, e2) => max_stack_bexp(a) + (List(max_stack_exp(e1), max_stack_exp(e2)).max)
-  case Write(e) => max_stack_exp(e) + 1
-  case Var(_) => 1
-  case Num(_) => 1
-  case Aop(_, a1, a2) => max_stack_exp(a1) + max_stack_exp(a2)
-  case Sequ(e1, e2) => List(max_stack_exp(e1), max_stack_exp(e2)).max
-}
-def max_stack_bexp(e: BExp): Int = e match {
-  case Bop(_, a1, a2) => max_stack_exp(a1) + max_stack_exp(a2)
-}
-
-// compiler - built-in functions 
-// copied from http://www.ceng.metu.edu.tr/courses/ceng444/link/jvm-cpm.html
-//
-
-val library = """
-.class public XXX.XXX
-.super java/lang/Object
-
-.method public static write(I)V 
-        .limit locals 5 
-        .limit stack 5 
-        iload 0 
-        getstatic java/lang/System/out Ljava/io/PrintStream; 
-        swap 
-        invokevirtual java/io/PrintStream/println(I)V 
-        return 
-.end method
-
-"""
-
-// for generating new labels
-var counter = -1
-
-def Fresh(x: String) = {
-  counter += 1
-  x ++ "_" ++ counter.toString()
-}
-
-// convenient string interpolations for
-// generating instructions, labels etc
-import scala.language.implicitConversions
-import scala.language.reflectiveCalls
-
-// convenience for code-generation (string interpolations)
-implicit def sring_inters(sc: StringContext) = new {
-  def i(args: Any*): String = "   " ++ sc.s(args:_*) ++ "\n"  // instructions
-  def l(args: Any*): String = sc.s(args:_*) ++ ":\n"          // labels
-  def m(args: Any*): String = sc.s(args:_*) ++ "\n"           // methods
-}
-
-// variable / index environments
-type Env = Map[String, Int]
-
-// compile expressions
-def compile_exp(a: Exp, env : Env) : String = a match {
-  case Num(i) => i"ldc $i"
-  case Var(s) => i"iload ${env(s)}"
-  case Aop("+", a1, a2) => compile_exp(a1, env) ++ compile_exp(a2, env) ++ i"iadd"
-  case Aop("-", a1, a2) => compile_exp(a1, env) ++ compile_exp(a2, env) ++ i"isub"
-  case Aop("*", a1, a2) => compile_exp(a1, env) ++ compile_exp(a2, env) ++ i"imul"
-  case Aop("/", a1, a2) => compile_exp(a1, env) ++ compile_exp(a2, env) ++ i"idiv"
-  case Aop("%", a1, a2) => compile_exp(a1, env) ++ compile_exp(a2, env) ++ i"irem"
-  case If(b, a1, a2) => {
-    val if_else = Fresh("If_else")
-    val if_end = Fresh("If_end")
-    compile_bexp(b, env, if_else) ++
-    compile_exp(a1, env) ++
-    i"goto $if_end" ++
-    l"$if_else" ++
-    compile_exp(a2, env) ++
-    l"$if_end"
-  }
-  case Call(name, args) => {
-    val is = "I" * args.length
-    args.map(a => compile_exp(a, env)).mkString ++
-    i"invokestatic XXX/XXX/$name($is)I"
-  }
-  case Sequ(a1, a2) => {
-    compile_exp(a1, env) ++ i"pop" ++ compile_exp(a2, env)
-  }
-  case Write(a1) => {
-    compile_exp(a1, env) ++
-    i"dup" ++
-    i"invokestatic XXX/XXX/write(I)V"
-  }
-}
-
-// compile boolean expressions
-def compile_bexp(b: BExp, env : Env, jmp: String) : String = b match {
-  case Bop("==", a1, a2) => 
-    compile_exp(a1, env) ++ compile_exp(a2, env) ++ i"if_icmpne $jmp"
-  case Bop("!=", a1, a2) => 
-    compile_exp(a1, env) ++ compile_exp(a2, env) ++ i"if_icmpeq $jmp"
-  case Bop("<", a1, a2) => 
-    compile_exp(a1, env) ++ compile_exp(a2, env) ++ i"if_icmpge $jmp"
-  case Bop("<=", a1, a2) => 
-    compile_exp(a1, env) ++ compile_exp(a2, env) ++ i"if_icmpgt $jmp"
-}
-
-// compile functions and declarations
-def compile_decl(d: Decl) : String = d match {
-  case Def(name, args, a) => { 
-    val env = args.zipWithIndex.toMap
-    val is = "I" * args.length
-    m".method public static $name($is)I" ++
-    m".limit locals ${args.length.toString}" ++
-    m".limit stack ${1 + max_stack_exp(a)}" ++
-    l"${name}_Start" ++   
-    compile_exp(a, env) ++
-    i"ireturn" ++
-    m".end method\n"
-  }
-  case Main(a) => {
-    m".method public static main([Ljava/lang/String;)V" ++
-    m".limit locals 200" ++
-    m".limit stack 200" ++
-    compile_exp(a, Map()) ++
-    i"invokestatic XXX/XXX/write(I)V" ++
-    i"return" ++
-    m".end method\n"
-  }
-}
-
-// the main compilation function
-def compile(prog: List[Decl], class_name: String) : String = {
-  val instructions = prog.map(compile_decl).mkString
-  (library + instructions).replaceAllLiterally("XXX", class_name)
-}
-
-
-
-
-// An example program (factorials)
-//
-// def fact(n) = if n == 0 then 1 else n * fact(n - 1);
-// def facT(n, acc) = if n == 0 then acc else facT(n - 1, n * acc);
-// 
-// fact(10) ; facT(15, 1)
-// 
-
-
-val test_prog = 
-  List(Def("fact", List("n"),
-         If(Bop("==",Var("n"),Num(0)),
-            Num(1),
-            Aop("*",Var("n"),
-                    Call("fact",List(Aop("-",Var("n"),Num(1))))))),
-
-       Def("facT",List("n", "acc"),
-         If(Bop("==",Var("n"),Num(0)),
-            Var("acc"),
-            Call("facT",List(Aop("-",Var("n"),Num(1)), 
-                             Aop("*",Var("n"),Var("acc")))))),
-
-       Main(Sequ(Write(Call("fact",List(Num(10)))),
-                 Write(Call("facT",List(Num(10), Num(1)))))))
-
-// prints out the JVM instructions
-println(compile(test_prog, "fact"))