cdecl.atg

一个Pascal语言分析器

COMPILER Decl
(* Translate simple C declarations into English
   Based on Kernighan and Ritchie: "C Programming language", page 122
   See also: Parr et.al. "PCCTS reference manual", page 53 in ACM SIGPLAN
   Notices 27(2), 88-165, 1992 *)

PROCEDURE GetNumber (VAR Int : INTEGER);
  VAR
    Error : INTEGER;
    S : STRING;
  BEGIN
    LexString(S);
    Int := 0; Val(S, Int, Error)
  END;

VAR
  Name, Tipe : STRING;
  Size : INTEGER;

CHARACTERS
  digit =  "0123456789" .
  letter = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyx_" .

IGNORE CHR(1) .. CHR(31)

TOKENS
  number = digit { digit } .
  name = letter { letter } .

PRODUCTIONS

  Decl = { name                               (. LexName(Tipe) .)
           Dcl                                (. WriteLn(' ', Tipe) .)
           ";" } .

  Dcl =     "*" Dcl                           (. Write(' pointer to') .)
           | DirectDcl .

  DirectDcl =   name                          (. LexName(Name);
                                                 Write(' ', Name, ' is') .)
                Descriptor
              | "(" Dcl ")" Descriptor .

  Descriptor = [  "["                         (. Write(' array ') .)
                  ( number                    (. GetNumber(Size);
                                                Write('[', Size, '] ') .)
                    | (* no dimension *)
                  )
                  "]"                         (. Write('of') .)
                  Descriptor
                | "(" ")"                     (. Write(' function returning') .)
               ] .

END Decl.