www.pudn.com > 12cocorc.zip > MOD2.ATG

COMPILER Mod2 
/* Alternative grammar for Modula-2 */ 
 
CHARACTERS 
  eol      = CHR(10) . 
  letter   = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" . 
  octDigit = "01234567" . 
  digit    = octDigit + '89'. 
  hexDigit = digit + 'ABCDEF'. 
  noQuote1 = ANY - "'" - eol . 
  noQuote2 = ANY - '"' - eol . 
 
IGNORE  CHR(9) .. CHR(13) 
 
COMMENTS 
  FROM '(*' TO '*)' NESTED 
 
TOKENS 
  id      =  letter { letter | digit }. 
  integer =    digit { digit } 
             | digit { digit }  CONTEXT ("..") 
             | octDigit { octDigit } ("B" | "C") 
             | digit { hexDigit } "H". 
  real    =  digit { digit } "." { digit } 
             [ "E" [ "+" | "-" ] digit { digit } ]. 
  string  =    "'" { noQuote1 } "'" 
             | '"' { noQuote2 } '"'. 
 
PRODUCTIONS 
  Mod2         =  DefMod | [ "IMPLEMENTATION" ] ProgMod . 
  ProgMod      =  "MODULE" id [ Priority ] ";" { Import } Block id "." . 
  Def          =    "CONST" { ConstDecl ";" } 
                  | "TYPE"  { id [ "=" Type ] ";" } 
                  | "VAR"   { VarDecl ";" } 
                  | ProcHead ";" . 
  DefMod       =  "DEFINITION" "MODULE" id ";" { Import } { Def } "END" id "." . 
  Import       =  "FROM" id "IMPORT" IdList ";" | "IMPORT" id { "," id } ";" . 
  Export       =  "EXPORT" [ "QUALIFIED" ] IdList ";" . 
  Priority     =  "[" ConstExpr "]" . 
  ModDecl      =  "MODULE" id [ Priority ] ";" { Import } [ Export ] Block id . 
  FormType     =  [ "ARRAY" "OF" ] QualId . 
  QualId       =  id { "." id } . 
  FPSect       =  [ "VAR" ] IdList ":" FormType . 
  FormPar      =  "(" [ FPSect { ";" FPSect } ] ")" [ ":" QualId ] . 
  Decl         =    "CONST" { ConstDecl ";" } 
                  | "TYPE"  { TypeDecl  ";" } 
                  | "VAR"   { VarDecl   ";" } 
                  | ProcDecl ";" 
                  | ModDecl  ";" . 
  Block        =  { Decl } [ "BEGIN"  StatSeq ] "END" . 
  StatSeq      =  Stat { ";" Stat } . 
  Stat         =  [ Design ( ":=" Expr | [ ActPar ] ) 
                  | IfStat  | CaseStat | LoopStat | ForStat 
                  | RepeatStat | WhileStat | WithStat 
                  | "EXIT" | "RETURN" [ Expr ] 
                  ] . 
  ProcHead     =  "PROCEDURE" id [ FormPar ] . 
  ProcDecl     =  ProcHead ";" ( Block id | "FORWARD" ) . 
  WithStat     =  "WITH" Design "DO" StatSeq "END" . 
  LoopStat     =  "LOOP" StatSeq "END" . 
  ForStat      =  "FOR" id ":=" Expr "TO" Expr [ "BY" ConstExpr ] 
                  "DO" StatSeq "END". 
  RepeatStat   =  "REPEAT" StatSeq "UNTIL" Expr  . 
  WhileStat    =  "WHILE" Expr "DO" StatSeq "END" . 
  Case         =  [ CaseLabList ":" StatSeq ] . 
  CaseStat     =  "CASE" Expr "OF" Case { "|" Case } [ "ELSE" StatSeq ] "END" . 
  IfStat       =  "IF" Expr "THEN" StatSeq 
                  { "ELSIF" Expr "THEN" StatSeq } 
                  [ "ELSE" StatSeq ] 
                  "END" . 
  ActPar       =  "(" [ ExpList ] ")" . 
  Elem         =  ConstExpr [ ".." ConstExpr ] . 
  Fact         =    integer | real | string | SetRest 
                  | id { SetRest | "." id | "[" ExpList "]" | "^" } [ ActPar ] 
                  | "(" Expr ")" 
                  | ( "NOT" | "~" ) Fact. 
  SetRest      =  "{" [ Elem { "," Elem } ] "}" . 
  MulOp        =  "*" | "/" | "DIV" | "REM" | "MOD" | "AND" | "&" . 
  Term         =  Fact { MulOp Fact }. 
  AddOp        =  "+" | "-" | "OR" . 
  SimExpr      =  [ "+" | "-" ] Term { AddOp Term }. 
  Rel          =  "=" | "#" | "<>" | "<" | "<=" | ">" | ">=" | "IN" . 
  Expr         =  SimExpr [ Rel SimExpr ] . 
  ConstDecl    =  id "=" ConstExpr . 
  ConstExpr    =  Expr. 
  TypeDecl     =  id "=" Type . 
  Type         =    SimType | ArrayType | RecType 
                  | SetType | PointerType | ProcType . 
  SimType      =    QualId [ "[" ConstExpr ".." ConstExpr "]" ] 
                  | Enum | "[" ConstExpr ".." ConstExpr "]" . 
  Enum         =  "(" IdList ")" . 
  IdList       =  id { "," id } . 
  ArrayType    =  "ARRAY" SimType { "," SimType } "OF" Type. 
  RecType      =  "RECORD" FieldListSeq "END" . 
  FieldListSeq =  FieldList { ";" FieldList } . 
  FieldList    =  [ IdList ":" Type 
                   | "CASE" [ id ] ":" QualId "OF" Variant { "|" Variant } 
                     [ "ELSE" FieldListSeq ] "END" 
                  ]. 
  Variant      =  [ CaseLabList ":" FieldListSeq ] . 
  CaseLabList  =  CaseLabs { "," CaseLabs } . 
  CaseLabs     =  ConstExpr [ ".." ConstExpr ] . 
  SetType      =  "SET" "OF" SimType . 
  PointerType  =  "POINTER" "TO" Type . 
  ProcType     =  "PROCEDURE" [ FormTypeList ] . 
  FormTypeList =  "(" [ [ "VAR" ] FormType { "," [ "VAR" ] FormType } ] ")" 
                  [ ":" QualId ] . 
  VarDecl      =  IdList ":" Type . 
  Design       =  id { "[" ExpList "]" | "^" | "." id }. 
  ExpList      =  Expr { "," Expr }. 
 
END Mod2.