(* P2 Pascal ATG for Coco/R *)
(* Wirth/Ammann Pascal-P2 (1972-73), as implemented by pcom *)
(* Uppercase only (CDC charset); probed against pcom, never fpc *)

(* Tags: P2, PASCALP2, WIRTH *)

COMPILER P2

CHARACTERS
  eol = CHR(13) .
  letter = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" .
  digit = "0123456789" .
  noQuote1 = ANY - "'" - eol .
IGNORE CHR(9) .. CHR(13)
COMMENTS FROM "(*" TO "*)"

TOKENS
  ident = letter { letter | digit } .
  pnumber = digit { digit } | digit { digit } CONTEXT ( ".." ) .
  preal = digit { digit } "." digit { digit } [ "E" [ "+" | "-" ] digit { digit } ] .
  pstring = "'" { noQuote1 | "''" } "'" .



PRODUCTIONS

  P2 = "PROGRAM" ident [ "(" ident { "," ident } ")" ] ";" Block "." .

  Block = DeclPart [ Compound ] .
  Compound = "BEGIN" Statements "END" .

  DeclPart = { LabelSection | ConstSection | TypeSection | VarSection | ProcDecl } .
  LabelSection = "LABEL" Label { "," Label } ";" .

  ConstSection = "CONST" [ ConstDecl { ";" [ ConstDecl ] } ] .
  ConstDecl = ident "=" Value .
  Value = [ "+" | "-" ] ( pnumber | preal | pstring | ident ) .

  TypeSection = "TYPE" [ TypeDecl { ";" [ TypeDecl ] } ] .
  TypeDecl = ident "=" Type .

  VarSection = "VAR" [ VarDecl { ";" [ VarDecl ] } ] .
  VarDecl = identlist ":" Type .
  ProcDecl = ( "PROCEDURE" | "FUNCTION" ) ident [ FormalParams ] [ ":" Type ] ";" ( "FORWARD" | Block ) ";" .
  FormalParams = "(" [ FormalGroup { ";" FormalGroup } ] ")" .
  FormalGroup = [ "VAR" ] identlist ":" Type
              | ( "PROCEDURE" | "FUNCTION" ) ident [ FormalParams ] [ ":" Type ] .

  identlist = ident { "," ident } .

  Type = SimpleType | StructType | PointerType | EnumType | TypeIdent .
  EnumType = "(" ident { "," ident } ")" .
  TypeIdent = ident [ ".." ( ident | [ "-" ] pnumber ) ] | [ "-" ] pnumber [ ".." ( ident | [ "-" ] pnumber ) ] .
  PointerType = "^" Type .

  SimpleType = integertype | realtype | charType | booleanType .

  integertype = "INTEGER" .
  realtype = "REAL" .
  charType = "CHAR" .
  booleanType = "BOOLEAN" .

  StructType = [ "PACKED" ] ( ArrayType | RecordType ) | SetType .

  ArrayType = "ARRAY" "[" Bound { "," Bound } "]" "OF" Type .

  Bound = SimpleType | Expr [ ".." Expr ] .

  RecordType = "RECORD" FieldList "END" .

  FieldList = [ Field { ";" [ Field ] } ] .

  Field = FieldListPart ":" Type | VariantPart .

  FieldListPart = ident { "," ident } .

  VariantPart = "CASE" Type ":" Type "OF" [ Variant { ";" [ Variant ] } ] .
  Variant = LabelList ":" "(" FieldList ")" .

  SetType = "SET" "OF" Type .

  Statements = [ Statement { ";" [ Statement ] } ] .

  IfStatement = "IF" Expr "THEN" Statement { "ELSE" Statement } .

  Statement = [ pnumber ":" ]
            ( IfStatement
            | CaseStmt
            | WhileStmt
            | RepeatStmt
            | ForStmt
            | GotoStmt
            | WithStmt
            | StdProcCall
            | ident IdentTail
            | Compound
            | ProcDecl ) .

  StdProcCall = StdProc "(" [ ParamList ] ")" .
  StdProc = "GET" | "PUT" | "RESET" | "REWRITE" | "READ" | "WRITE"
          | "PACK" | "UNPACK" | "NEW" | "RELEASE" | "READLN" | "WRITELN" | "MARK" .

  CaseStmt = "CASE" Expr "OF" [ CaseItem { ";" [ CaseItem ] } ] "END" .

  CaseItem = CaseLabelList ":" Statement .

  CaseLabelList = CaseLabel { "," CaseLabel } .
  CaseLabel = pnumber | ident | pstring .

  LabelList = Label { "," Label } .

  Label = pnumber .

  WhileStmt = "WHILE" Expr "DO" Statement .

  RepeatStmt = "REPEAT" Statements "UNTIL" Expr .

  ForStmt = "FOR" ident ":=" Expr ( "TO" | "DOWNTO" ) Expr "DO" Statement .

  IdentTail = [ Selector { Selector } ] [ ":=" Expr | "(" [ ParamList ] ")" ] .
  Selector = "." ident | "[" Expr { "," Expr } "]" | "^" .


  ParamList = Param { "," Param } .

  Param = Expr [ ":" Expr [ ":" Expr ] ] .

  WithStmt = "WITH" WithItem { "," WithItem } "DO" Statement .
  WithItem = ident .

  GotoStmt = "GOTO" Label .

  Expr = SimpleExpr [ ( Relationship | "IN" ) SimpleExpr ] .

  Relationship = "=" | "<" | ">" | "<=" | ">=" | "<>" .

  SimpleExpr = ["+" | "-"] Term { ("+" | "-" | "OR") Term } .

  Term = Factor { ("*" | "/" | "DIV" | "MOD" | "AND") Factor } .

  Factor = ["+" | "-"] ["NOT"] Primary .

  Primary = pnumber | preal | pstring | "NIL" | StdFuncCall | "(" Expr ")" | ident { Selector } [ "(" [ ParamList ] ")" ] .
  StdFuncCall = StdFunc "(" [ ParamList ] ")" .
  StdFunc = "ABS" | "SQR" | "TRUNC" | "ODD" | "ORD" | "CHR"
          | "PRED" | "SUCC" | "EOF" | "EOLN" | "SIN" | "COS" | "EXP" | "SQRT" | "LN" | "ARCTAN" .



END P2.