M2compiler-V3/compiler/tests/showcase12.mod

MODULE Showcase12;
// Step-8.2/8.3 showcase. Exercises, in one small session:
//   - named-CONST folding in an array bound (M = N*2-1)
//   - a forward pointer type (Link = POINTER TO Node; Node later)
//   - a trailing ';' before a record's END
//   - empty statements (';;' and a lone ';')
//   - 1-character string literals passed to ARRAY OF CHAR
//   - a qualified type name (Showcase12Lib.Point) and qualified call
// Expected ExitCode: 42.
IMPORT Showcase12Lib;

CONST
  N = 4;              // folded: N used below
  M = N * 2 - 1;      // folds to 7 — the bound of Vec

TYPE
  Vec  = ARRAY [0 .. M] OF INTEGER;   // 8 elements
  Link = POINTER TO Node;             // forward: Node is declared later
  Node = RECORD
    value : INTEGER;
    next  : Link;      // trailing ';' before END is accepted
  END;

VAR
  ExitCode : INTEGER;
  v        : Vec;
  head     : Link;
  pt       : Showcase12Lib.Point;     // qualified type name
  i, sum   : INTEGER;

BEGIN
  sum := 0;
  FOR i := 0 TO M DO v[i] := i; sum := sum + v[i] END;;  // 0+..+7 = 28
  ;                                                     // empty statement
  NEW(head); head^.value := 9; head^.next := NIL;
  sum := sum + head^.value;                             // 37
  sum := sum + Showcase12Lib.Score("A")
            + Showcase12Lib.Score("B");                 // +2+3 = 42
  pt.x := 42;
  IF sum = pt.x THEN ExitCode := sum ELSE ExitCode := 1 END
END Showcase12.