Binary file pics/getting-info-from-the-internet.jpg has changed

--- a/progs/compile.scala	Thu Nov 14 01:21:02 2019 +0000
+++ b/progs/compile.scala	Thu Nov 14 13:17:02 2019 +0000
@@ -118,6 +118,9 @@
     def l(args: Any*): String = sc.s(args:_*) ++ ":\n"
 }
 
+// this allows you to write things like
+// i"add" and l"Lable"
+
 
 // environments 
 type Env = Map[String, Int]
@@ -132,16 +135,17 @@
 // 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 Var(s) => i"iload ${env(s)} \t\t; $s"
   case Aop(op, a1, a2) => 
     compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ compile_op(op)
 }
 
 // boolean expression compilation
+//  - the jump-label is for where to jump if the condition is not true
 def compile_bexp(b: BExp, env : Env, jmp: String) : String = b match {
   case True => ""
   case False => i"goto $jmp"
-  case Bop("=", a1, a2) => 
+  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"
@@ -153,8 +157,8 @@
 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
-    (compile_aexp(a, env) ++ i"istore $index", env + (x -> index))
+    val index = env.getOrElse(x, env.keys.size)
+    (compile_aexp(a, env) ++ i"istore $index \t\t; $x", env + (x -> index))
   } 
   case If(b, bl1, bl2) => {
     val if_else = Fresh("If_else")
@@ -179,12 +183,12 @@
      l"$loop_end", env1)
   }
   case Write(x) => 
-    (i"iload ${env(x)}" ++ 
+    (i"iload ${env(x)} \t\t; $x" ++ 
      i"invokestatic XXX/XXX/write(I)V", env)
   case Read(x) => {
-    val index = if (env.isDefinedAt(x)) env(x) else env.keys.size
+    val index = env.getOrElse(x, env.keys.size) 
     (i"invokestatic XXX/XXX/read()I" ++ 
-     i"istore $index", env + (x -> index))
+     i"istore $index \t\t; $x", env + (x -> index))
   }
 }
 
@@ -266,6 +270,11 @@
        Write("minus1"))                 //  write minus1
 
 
+// the compiled file as string
+//
+//println(compile(fib_test, "fib"))
+
+
 compile_run(fib_test, "fib")
 
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/toks.scala	Thu Nov 14 13:17:02 2019 +0000
@@ -0,0 +1,136 @@
+abstract class Token
+case object T_SEMI extends Token
+case object T_LPAREN extends Token
+case object T_RPAREN extends Token
+case class T_ID(s: String) extends Token
+case class T_OP(s: String) extends Token
+case class T_NUM(n: Int) extends Token
+case class T_KWD(s: String) extends Token
+case class T_STR(s: String) extends Token
+
+
+// Loops program
+//===============
+
+/*
+start := 1000; 
+x := start;
+y := start;
+z := start;
+while 0 < x do {
+ while 0 < y do {
+  while 0 < z do { z := z - 1 };
+  z := start;
+  y := y - 1
+ };     
+ y := start;
+ x := x - 1
+}
+*/
+
+val loops =
+  List(T_ID("start"), T_OP(":="), T_NUM(1000), T_SEMI, T_ID("x"), T_OP(":="), 
+       T_ID("start"), T_SEMI, T_ID("y"), T_OP(":="), T_ID("start"), T_SEMI, 
+       T_ID("z"), T_OP(":="), T_ID("start"), T_SEMI, T_KWD("while"), T_NUM(0), 
+       T_OP("<"), T_ID("x"), T_KWD("do"), T_LPAREN, T_KWD("while"), T_NUM(0), 
+       T_OP("<"), T_ID("y"), T_KWD("do"), T_LPAREN, T_KWD("while"), T_NUM(0), 
+       T_OP("<"), T_ID("z"), T_KWD("do"), T_LPAREN, T_ID("z"), T_OP(":="), 
+       T_ID("z"), T_OP("-"), T_NUM(1), T_RPAREN, T_SEMI, T_ID("z"), T_OP(":="),
+       T_ID("start"), T_SEMI, T_ID("y"), T_OP(":="), T_ID("y"), T_OP("-"), 
+       T_NUM(1), T_RPAREN, T_SEMI, T_ID("y"), T_OP(":="), T_ID("start"), 
+       T_SEMI, T_ID("x"), T_OP(":="), T_ID("x"), T_OP("-"), T_NUM(1), T_RPAREN) 
+
+
+// Fib program
+//=============
+
+/*
+write "Fib";
+read n;  
+minus1 := 0;
+minus2 := 1;
+while n > 0 do {
+       temp := minus2;
+       minus2 := minus1 + minus2;
+       minus1 := temp;
+       n := n - 1
+};
+write "Result";
+write minus2
+*/
+
+val fib =
+  List(T_KWD("write"), T_STR("Fib"), T_SEMI, T_KWD("read"), T_ID("n"), 
+       T_SEMI, T_ID("minus1"), T_OP(":="), T_NUM(0), T_SEMI, T_ID("minus2"), 
+       T_OP(":="), T_NUM(1), T_SEMI, T_KWD("while"), T_ID("n"), T_OP(">"), 
+       T_NUM(0), T_KWD("do"), T_LPAREN, T_ID("temp"), T_OP(":="), 
+       T_ID("minus2"), T_SEMI, T_ID("minus2"), T_OP(":="), T_ID("minus1"), 
+       T_OP("+"), T_ID("minus2"), T_SEMI, T_ID("minus1"), T_OP(":="), 
+       T_ID("temp"), T_SEMI, T_ID("n"), T_OP(":="), T_ID("n"), T_OP("-"), 
+       T_NUM(1), T_RPAREN, T_SEMI, T_KWD("write"), T_STR("Result"), T_SEMI, 
+       T_KWD("write"), T_ID("minus2"))
+
+
+
+// Factors program
+//=================
+
+/*
+write "Input n please";
+read n;
+write "The factors of n are";
+f := 2;
+while n != 1 do {
+    while (n / f) * f == n do {
+        write f;
+        n := n / f
+    };
+    f := f + 1
+}
+*/
+
+val factors = 
+  List(T_KWD("write"), T_STR("Input n please"), T_SEMI, T_KWD("read"), 
+       T_ID("n"), T_SEMI, T_KWD("write"), T_STR("The factors of n are"), 
+       T_SEMI, T_ID("f"), T_OP(":="), T_NUM(2), T_SEMI, T_KWD("while"), 
+       T_ID("n"), T_OP("!="), T_NUM(1), T_KWD("do"), T_LPAREN, 
+       T_KWD("while"), T_ID("n"), T_OP("/"), T_ID("f"), T_OP("*"), 
+       T_ID("f"), T_OP("=="), T_ID("n"), T_KWD("do"), T_LPAREN, 
+       T_KWD("write"), T_ID("f"), T_SEMI, T_ID("n"), T_OP(":="), 
+       T_ID("n"), T_OP("/"), T_ID("f"), T_RPAREN, T_SEMI, T_ID("f"), 
+       T_OP(":="), T_ID("f"), T_OP("+"), T_NUM(1), T_RPAREN)
+
+
+// Primes program
+//================
+
+/*
+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
+}
+*/
+
+val primes =
+  List(T_ID("end"), T_OP(":="), T_NUM(100), T_SEMI, T_ID("n"), T_OP(":="), 
+       T_NUM(2), T_SEMI, T_KWD("while"), T_ID("n"), T_OP("<"), T_ID("end"), 
+       T_KWD("do"), T_LPAREN, T_ID("f"), T_OP(":="), T_NUM(2), T_SEMI, 
+       T_ID("tmp"), T_OP(":="), T_NUM(0), T_SEMI, T_KWD("while"), T_ID("f"), 
+       T_OP("<"), T_ID("n"), T_OP("/"), T_NUM(2), T_OP("+"), T_NUM(1), 
+       T_OP("&&"), T_ID("tmp"), T_OP("=="), T_NUM(0), T_KWD("do"), T_LPAREN, 
+       T_KWD("if"), T_ID("n"), T_OP("/"), T_ID("f"), T_OP("*"), T_ID("f"), 
+       T_OP("=="), T_ID("n"), T_KWD("then"), T_LPAREN, T_ID("tmp"), T_OP(":="),
+       T_NUM(1), T_RPAREN, T_KWD("else"), T_LPAREN, T_KWD("skip"), T_RPAREN, 
+       T_SEMI, T_ID("f"), T_OP(":="), T_ID("f"), T_OP("+"), T_NUM(1), 
+       T_RPAREN, T_SEMI, T_KWD("if"), T_ID("tmp"), T_OP("=="), T_NUM(0), 
+       T_KWD("then"), T_LPAREN, T_KWD("write"), T_ID("n"), T_RPAREN, 
+       T_KWD("else"), T_LPAREN, T_KWD("skip"), T_RPAREN, T_SEMI, T_ID("n"), 
+       T_OP(":="), T_ID("n"), T_OP("+"), T_NUM(1), T_RPAREN)

Binary file slides/getting-info-from-the-internet.jpg has changed

Binary file slides/slides07.pdf has changed

--- a/slides/slides07.tex	Thu Nov 14 01:21:02 2019 +0000
+++ b/slides/slides07.tex	Thu Nov 14 13:17:02 2019 +0000
@@ -66,7 +66,8 @@
 \begin{itemize}
 \item you consume one or more token from the\\ 
   input (stream)
-\item \bl{\texttt{T\_NUM(1), T\_OP(+), T\_NUM(2)}}
+\item \bl{\texttt{T\_NUM(1), T\_OP(+), T\_NUM(2)}}\bigskip
+\item a good starting point would be \texttt{comb2.scala}
 \end{itemize}
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%