diff -r 1e6eca42d90b -r 8778d23fef92 cw2_marking/c4.sc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cw2_marking/c4.sc	Mon Feb 03 12:34:38 2025 +0000
@@ -0,0 +1,123 @@
+// for testing tokenisation
+
+import scala.util.{Try, Success, Failure}
+import $file.cw024_add
+import cw024_add._
+
+def listcmp[A](xs: List[A], ys: List[A]): List[A] = (xs, ys) match {
+  case (Nil, Nil) => Nil
+  case (x::xs, y::ys) => if (x == y) listcmp(xs, ys) else (x::xs)
+  case _ => xs
+} 
+
+
+// some students eliminated "..." therefore a specific comparison function
+def lsteq(xs: List[Token], ys: List[Token]): Boolean = (xs, ys) match {
+  case (Nil, Nil) => true
+  case (T_STRING(s1)::xs, T_STRING(s2)::ys) => 
+    (s1 == s2 || s2.drop(1).dropRight(1) == s1) && lsteq(xs, ys)
+  case (x::xs, y::ys) => x == y && lsteq(xs, ys)
+  case _ => false
+} 
+
+// some students kept string T_Num
+import scala.language.implicitConversions
+given Conversion[Int, String] = (n => n.toString)
+given Conversion[String,Char] = (s => s.head)
+
+// programs to test (and number of toplevel definitions)
+//val uregs = List((RECD("x", PLUS(CHAR('a'))), "aaa")) 
+
+val tks = 
+  List(T_ID("bnd"), 
+       T_OP(":="), 
+       T_NUM(1), 
+       T_SEMI, 
+       T_KEYWORD("while"), 
+       T_ID("bnd"), 
+       T_OP("<"), 
+       T_NUM(101), 
+       T_KEYWORD("do"), 
+       T_PAREN("{"), 
+       T_KEYWORD("write"), 
+       T_ID("bnd"), 
+       T_SEMI, 
+       T_KEYWORD("write"), 
+       T_STRING("\": \""), 
+       T_SEMI, 
+       T_ID("n"), 
+       T_OP(":="), 
+       T_ID("bnd"), 
+       T_SEMI, 
+       T_ID("cnt"), 
+       T_OP(":="), 
+       T_NUM(0), 
+       T_SEMI, 
+       T_KEYWORD("while"), 
+       T_ID("n"), 
+       T_OP(">"), 
+       T_NUM(1), 
+       T_KEYWORD("do"), 
+       T_PAREN("{"), 
+       T_KEYWORD("write"), 
+       T_ID("n"), 
+       T_SEMI, 
+       T_KEYWORD("write"), 
+       T_STRING("\",\""), 
+       T_SEMI, 
+       T_KEYWORD("if"), 
+       T_ID("n"), 
+       T_OP("%"), 
+       T_NUM(2), 
+       T_OP("=="), 
+       T_NUM(0), 
+       T_KEYWORD("then"), 
+       T_ID("n"), 
+       T_OP(":="), 
+       T_ID("n"), 
+       T_OP("/"), 
+       T_NUM(2), 
+       T_KEYWORD("else"), 
+       T_ID("n"), 
+       T_OP(":="), 
+       T_NUM(3), 
+       T_OP("*"), 
+       T_ID("n"), 
+       T_OP("+"), 
+       T_NUM(1), 
+       T_SEMI, 
+       T_ID("cnt"), 
+       T_OP(":="), 
+       T_ID("cnt"), 
+       T_OP("+"), 
+       T_NUM(1), 
+       T_PAREN("}"), 
+       T_SEMI, 
+       T_KEYWORD("write"), 
+       T_STRING("\" => \""), 
+       T_SEMI, 
+       T_KEYWORD("write"), 
+       T_ID("cnt"), 
+       T_SEMI, 
+       T_KEYWORD("write"), 
+       T_STRING("\"\\n\""), 
+       T_SEMI, 
+       T_ID("bnd"), 
+       T_OP(":="), 
+       T_ID("bnd"), 
+       T_OP("+"), 
+       T_NUM(1), 
+       T_PAREN("}"))
+
+
+
+  //print(s"  Testing lexing of ${file.padTo(16, ' ')} ")
+val str = os.read(os.pwd / "collatz2.while")
+  
+Try(test_string(str)) match {
+  case Success(v) if lsteq(v, tks) 
+                  => println(s"   Generated the correct token sequence.")
+  case Success(v) => println(s"   Generated $v\n instead of\n $tks\n\n${listcmp(v, tks)}).") ; throw new Exception("Different")
+  case Failure(e) => println(s"   Exception raised.") ; throw(e)
+}
+