Project-Oberon-BlackBox/BlackBox/Po/Files/OberonSyntax.Text

digit  =   "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9".
hexDigit  =  digit | "A" | "B" | "C" | "D" | "E" | "F".
ident  =  letter {letter | digit}.
qualident  =  [ident "."] ident.
identdef = ident ["*"].
integer  =  digit {digit} | digit {hexDigit} "H".
real  =  digit {digit} "." {digit} [ScaleFactor].
ScaleFactor  =  ("E" |"D") ["+" | "-"] digit {digit}.
number  =  integer | real.
string  =  "'" {character} "'" | digit {hexdigit} "X".
ConstDeclaration  =  identdef "=" ConstExpression.
ConstExpression  =  expression.
TypeDeclaration  =  identdef "=" StrucType.
StrucType  =  ArrayType | RecordType | PointerType | ProcedureType.
type  =  qualident | StrucType.
ArrayType  =  "ARRAY" length {"," length} "OF" type.
length  =  ConstExpression.
RecordType  =  "RECORD" ["(" BaseType ")"] [FieldListSequence] "END".
BaseType  =  qualident.
FieldListSequence  =  FieldList {";" FieldList}.
FieldList  =  IdentList ":" type.
IdentList  =  identdef {"," identdef}.
PointerType  =  "POINTER" "TO" type.
ProcedureType  =  "PROCEDURE" [FormalParameters].
VariableDeclaration  =  IdentList ":" type.
expression  =  SimpleExpression [relation SimpleExpression].
relation  =  "=" | "#" | "<" | "<=" | ">" | ">=" | "IN" | "IS".
SimpleExpression  =  ["+" | "-"] term {AddOperator term}.
AddOperator  =  "+" | "-" | "OR".
term  =  factor {MulOperator factor}.
MulOperator  =  "*" | "/" | "DIV" | "MOD" | "&".
factor  =  number | string | "NIL" | "TRUE" | "FALSE" |
  set | designator [ActualParameters] | "(" expression ")" | "~" factor.
designator  =  qualident {selector}.
selector  =  "." ident | "[" ExpList "]" | "^" |  "(" qualident ")".
set  =  "{" [element {"," element}] "}".
element  =  expression [".." expression].
ExpList  =  expression {"," expression}.
ActualParameters  =  "(" [ExpList] ")" .
statement  =  [assignment | ProcedureCall | IfStatement | CaseStatement |
  WhileStatement | RepeatStatement | ForStatement].
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} "END".
Case  =  CaseLabelList ":"  StatementSequence.
CaseLabelList  = LabelRange {"," LabelRange}.
LabelRange  =  label [".." label].
label  =  integer | string | ident.
WhileStatement  =  "WHILE" expression "DO" StatementSequence
{"ELSIF" expression "DO" StatementSequence} "END".
RepeatStatement  =  "REPEAT" StatementSequence "UNTIL" expression.
ForStatement  =  "FOR" ident ":=" expression "TO" expression ["BY" ConstExpression]
"DO" StatementSequence "END".
ProcedureDeclaration  =  ProcedureHeading ";" ProcedureBody ident.
ProcedureHeading  =  "PROCEDURE" identdef [FormalParameters].
ProcedureBody  =  DeclarationSequence ["BEGIN" StatementSequence]
    ["RETURN" expression] "END".
DeclarationSequence  =  ["CONST" {ConstDeclaration ";"}]
  ["TYPE" {TypeDeclaration ";"}]
  ["VAR" {VariableDeclaration ";"}]
  {ProcedureDeclaration ";"}.
FormalParameters  =  "(" [FPSection {";" FPSection}] ")" [":" qualident].
FPSection  =  ["CONST" | "VAR"] ident {"," ident} ":" FormalType.
FormalType  =  ["ARRAY" "OF"] qualident.
module  =  "MODULE" ident ";" [ImportList] DeclarationSequence
  ["BEGIN" StatementSequence] "END" ident "." .
ImportList  =  "IMPORT" import {"," import} ";".
import  =  ident [":=" ident].