COMPILER MAda
/* A micro subset of Ada as used by H Dobler in "Compilerbau I". */

IGNORE CASE

CHARACTERS
  letter      = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".
  digit       = "0123456789".
  eol         = CHR(10) .
  anyButQuote = ANY - '"' - eol .

COMMENTS
  FROM "--" TO eol

TOKENS
  id     = letter { ["_"] (letter | digit) }.
  number = digit { ["_"] digit }.
  string = '"' { anyButQuote | '""' } '"'.

PRODUCTIONS
  MAda        =  "PACKAGE" id "IS" {Declaration} "BEGIN" {Stat} "END" [id] ";".
  Declaration =  ObjsDecl | ProcDecl.
  ObjsDecl    =  IdList ":" Type.
  IdList      =  id {"," id}.
  Type        =  "ARRAY" "(" Range ")" "OF" SimpleType.
  SimpleType  =  "INTEGER" | "CHARACTER" | "BOOLEAN".
  ProcDecl    =  "PROCEDURE" id FormalPart 
                 ["IS" {Declaration} "BEGIN" {Stat} "END" [id]] ";".
  FormalPart  =  ["(" ParamDecl {";" ParamDecl} ")"].
  ParamDecl   =  IdList ":" [ParamMode] ["ARRAY" "OF"] SimpleType.
  ParamMode   =  "IN" ["OUT"] | "OUT".
  Stat        =    Name ":=" Expr ";"
                 | Name ";"
                 | "IF" Expr "THEN" {Stat}
                     ["ELSIF" Expr "THEN" {Stat}] ["ELSE" {Stat}] "END" "IF" ";"
                 | [id ":"] [IterClause] "LOOP" {Stat} "END" "LOOP" ";"
                 | "EXIT" [id] ["WHEN" Expr] ";"
                 | "RETURN" ";"
                 | "NULL" ";"
                 | "READ" "(" Name "," Name ")" ";"
                 | "READLN" "(" Name ")" ";"
                 | "WRITE" "(" Expr ["," Expr] ")" ";"
                 | "WRITELN" ";".
  IterClause  =  "WHILE" Expr | "FOR" id "IN" ["REVERSE"] Range.
  Range       =  Expr ".." Expr.
  Name        =  id [NameSuffix] | SimpleType "'" "VAL" "(" Expr ")".
  NameSuffix  =    "(" Expr {"," Expr} ")" | "'" "CHAR"
                 | "'" "FIRST" | "'" "LAST".
  Expr        =  Relation [ ( "AND" ["THEN"] | "OR" ["ELSE"] ) Relation].
  Relation    =  SimpleExpr [RelOp SimpleExpr].
  SimpleExpr  =  [AddOp] Term {AddOp Term}.
  Term        =  Factor {MulOp Factor}.
  Factor      =  [ "NOT" | "ABS" ] Primary.
  Primary     =  Name | number | string | "TRUE" | "FALSE" | "(" Expr ")".
  RelOp       =  "<" | "<=" | "=" | "/=" | ">=" | ">".
  AddOp       =  "+" | "-".
  MulOp       =  "*" | "/" | "MOD".

END MAda.