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COMPILER Mod2 
/* COCO/R Grammar for Modula-2 based on "Programming in 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 
  ident   =  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                 = DefinitionModule | [ "IMPLEMENTATION" ] ProgramModule . 
  Number               = integer | real . 
  QualIdent            = ident { "." ident } . 
  ConstantDeclaration  = ident "=" ConstExpression . 
  ConstExpression      = Expression . 
  TypeDeclaration      = ident "=" Type . 
  Type                 =   SimpleType | ArrayType | RecordType | SetType 
                         | PointerType | ProcedureType . 
  SimpleType           = QualIdent | Enumeration | SubrangeType . 
  Enumeration          = "(" IdentList ")" . 
  IdentList            = ident { "," ident } . 
  SubrangeType         = [ ident ] "[" ConstExpression ".." ConstExpression "]" . 
  ArrayType            = "ARRAY" SimpleType { "," SimpleType } "OF" Type . 
  RecordType           = "RECORD" FieldListSequence "END" . 
  FieldListSequence    = FieldList { ";" FieldList } . 
  FieldList            =   [ IdentList ":" Type 
                         | "CASE" [ ident ] ":" QualIdent "OF" 
                           Variant { "|" Variant } 
                           [ "ELSE" FieldListSequence ] "END" ] . 
  Variant              = [ CaseLabelList ":" FieldListSequence ] . 
  CaseLabelList        = CaseLabels { "," CaseLabels } . 
  CaseLabels           = ConstExpression [ ".." ConstExpression ] . 
  SetType              = "SET" "OF" SimpleType . 
  PointerType          = "POINTER" "TO" Type . 
  ProcedureType        = "PROCEDURE" [ FormalTypeList ] . 
  FormalTypeList       = "(" [ [ "VAR" ] FormalType 
                         { "," [ "VAR" ] FormalType } ] ")" [ ":" QualIdent ] . 
  VariableDeclaration  = IdentList ":" Type . 
  Designator           = QualIdent { "." ident | "[" ExpList "]" | "^" } . 
  ExpList              = Expression { "," Expression } . 
  Expression           = SimpleExpression [ Relation SimpleExpression ] . 
  Relation             = "=" | "#" | "<" |"<=" | ">" | ">=" | "IN" . 
  SimpleExpression     = [ "+" | "-" ] Term { AddOperator Term } . 
  AddOperator          = "+" | "-" | "OR" . 
  Term                 = Factor { MulOperator Factor } . 
  MulOperator          = "*" |"/" | "DIV" | "MOD" | "AND" . 
  Factor               =   Number | string | Set | "NOT" Factor 
                         | Designator [ ActualParameters ] 
                         | "(" Expression ")" . 
  Set                  = [ QualIdent ] "{" [ Element { "," Element } ] "}" . 
  Element              = Expression [ ".." Expression ] . 
  ActualParameters     = "(" [ ExpList ] ")" . 
  Statement            = [  Assignment | ProcedureCall | IfStatement 
                          | CaseStatement | WhileStatement | RepeatStatement 
                          | LoopStatement | ForStatement | WithStatement 
                          | "EXIT" | "RETURN" [ Expression ] ] . 
  Assignment           = Designator ":=" Expression . 
  ProcedureCall        = Designator [ ActualParameters ] . 
  StatementSequence    = Statement { ";" Statement } . 
  IfStatement          = "IF" Expression "THEN" StatementSequence 
                         { "ELSIF" Expression "THEN" StatementSequence } 
                         [ "ELSE" StatementSequence ] "END" . 
  CaseStatement        = "CASE" Expression "OF" Case { "|" Case } 
                         [ "ELSE" StatementSequence ] "END" . 
  Case                 = [ CaseLabelList ":" StatementSequence ] . 
  WhileStatement       = "WHILE" Expression "DO" StatementSequence "END" . 
  RepeatStatement      = "REPEAT" StatementSequence "UNTIL" Expression . 
  ForStatement         = "FOR" ident ":=" Expression "TO" Expression 
                         [ "BY" ConstExpression ] "DO" StatementSequence "END" . 
  LoopStatement        = "LOOP" StatementSequence "END" . 
  WithStatement        = "WITH" Designator "DO" StatementSequence "END" . 
  ProcedureDeclaration = ProcedureHeading ";" Block ident . 
  ProcedureHeading     = "PROCEDURE" ident [ FormalParameters ] . 
  Block                = { Declaration } [ "BEGIN" StatementSequence ] "END" . 
  Declaration          =   "CONST" { ConstantDeclaration ";" } 
                         | "TYPE" { TypeDeclaration ";" } 
                         | "VAR" { VariableDeclaration ";" } 
                         | ProcedureDeclaration ";" 
                         | ModuleDeclaration ";" . 
  FormalParameters     = "(" [ FPSection { ";" FPSection } ] ")" 
                         [ ":" QualIdent ] . 
  FPSection            = [ "VAR" ] IdentList ":" FormalType . 
  FormalType           = [ "ARRAY" "OF" ] QualIdent . 
  ModuleDeclaration    = "MODULE" ident [ Priority ] ";" 
                         [ Import ] [ Export ] Block ident . 
  Priority             = "[" ConstExpression "]" . 
  Export               = "EXPORT" [ "QUALIFIED" ] IdentList ";" . 
  Import               = [ "FROM" ident ] "IMPORT" IdentList ";" . 
  DefinitionModule     = "DEFINITION" "MODULE" ident ";" 
                         { Import } { Definition } "END" ident "." . 
  Definition           =   "CONST" { ConstantDeclaration ";" } | 
                         | "TYPE" { ident [ "=" Type ] ";" } 
                         | "VAR" { VariableDeclaration ";" } 
                         | ProcedureHeading ";" . 
  ProgramModule        = "MODULE" ident [ Priority ] ";" 
                         { Import } Block ident "." . 
 
END Mod2.