Language/OS - Multiplatform Resource Library/LANGUAGE OS.iso/txl/modula2.lha/Modula2/Modula2.Grammar

Text File | 1993-07-19 | 8KB | 485 lines

% Die Syntax von Modula-2
%    aus Anhang 1, Niklaus Wirth,
%    "Programmieren in Modula-2", Springer Verlag 1985
% J.R. Cordy, GMD Karlsruhe, 23.10.90

compounds
    <>  <=  >=  ..  :=
end compounds

comments
      (* *)
end comments

keys
    IN  OR  DIV  MOD  AND  NOT
    ARRAY  OF  RECORD  END  CASE  ELSE  SET  POINTER  TO  PROCEDURE
    VAR  EXIT  RETURN  IF  THEN  WHILE  DO  REPEAT  UNTIL  FOR  BY
    LOOP  WITH  BEGIN  MODULE  EXPORT  QUALIFIED
    FROM  IMPORT  DEFINITION  IMPLEMENTATION
end keys

define program
    [CompilationUnit]
end define

define qualident
    [id] [repeat dot_Ident]
end define

define dot_Ident
    . [id]
end define

define ConstantDeclaration
    [id] = [ConstExpression]
end define

define ConstExpression
    [SimpleConstExpr] [repeat relation_SimpleConstExpr]
end define

define relation_SimpleConstExpr
      [relation] [SimpleConstExpr]
end define

define relation
    = | # | <> | < | <= | > | >= | IN
end define

define SimpleConstExpr
      [opt sign]  [ConstTerm] [repeat AddOperator_ConstTerm]
end define

define sign
    + | -
end define

define AddOperator_ConstTerm
    [AddOperator] [ConstTerm]
end define

define AddOperator
    + | - | OR
end define

define ConstTerm
    [ConstFactor] [repeat MulOperator_ConstFactor]
end define

define MulOperator_ConstFactor
    [MulOperator] [ConstFactor]
end define

define MulOperator
    * | / | DIV | MOD | AND | &
end define

define ConstFactor
    [qualident]
    |    [number]
    |    [stringlit]
    |    [ConstSet]
    |    ( [ConstExpression] )
    |    NOT [ConstFactor]
end define

define ConstSet
    [qualident] { [list ConstElement] }
end define

define ConstElement
    [ConstExpression] [opt dotdot_ConstExpression]
end define

define dotdot_ConstExpression
    .. [ConstExpression]
end define

define TypeDeclaration
    [id] = [type]
end define

define type
    [SimpleType]
    |    [ArrayType]
    |    [RecordType]
    |    [SetType]
    |    [PointerType]
    |    [ProcedureType]
end define

define SimpleType
    [qualident]
    |    [enumeration]
    |    [SubrangeType]
end define

define enumeration
    ( [IdentList] )
end define

define IdentList
    [list id+]
end define

define SubrangeType
    [opt id] '[ [ConstExpression] .. [ConstExpression] ']
end define

define ArrayType
    ARRAY [list SimpleType+] OF [type]
end define

define RecordType
                    [IN][NL]
    RECORD             [NL][IN]
        [FieldListSequence]    [NL][EX]
    END            [EX]
end define

define FieldListSequence
    [FieldList] [repeat semi_FieldList]
end define

define semi_FieldList
    ;        [NL]
    [FieldList]
end define

define FieldList
    [IdentList] : [type]
    |    CASE [opt id] : [qualident] OF         [IN][NL]
        [variant]
        [repeat or_variant]
        [opt else_FieldListSequence]    [EX]
    END
end define

define or_variant
    OR [variant]
end define

define else_FieldListSequence
    ELSE             [IN][NL]
        [FieldListSequence]    [EX][NL]
end define

define variant
    [CaseLabelList] :     [IN][NL]
        [FieldListSequence]    [EX][NL]
end define

define CaseLabelList
    [list CaseLabels+]
end define

define CaseLabels
    [ConstExpression] [opt dotdot_ConstExpression]
end define

define SetType
    SET OF [SimpleType]
end define

define PointerType
    POINTER TO [type]
end define

define ProcedureType
    PROCEDURE [FormalTypeList]
end define

define FormalTypeList
    ( [list optVar_FormalType+] ) [opt ProcedureResult]
end define

define optVar_FormalType
    [opt 'VAR] [FormalType]
end define

define VariableDeclaration
    [IdentList] : [type]
end define

define designator
    [qualident] [repeat dotSubscriptOrArrow]
end define

define dotSubscriptOrArrow
    . [id]
    |    '[ [ExpList] ']
    |    ^
end define

define ExpList
    [list expression+]
end define

define expression
    [SimpleExpression] [opt relation_SimpleExpression]
end define

define relation_SimpleExpression
    [relation] [SimpleExpression]
end define

define SimpleExpression
    [opt sign] [term] [repeat AddOperator_term]
end define

define AddOperator_term
    [AddOperator] [term]
end define

define term
    [factor] [repeat MulOperator_factor]
end define

define MulOperator_factor
    [MulOperator] [factor]
end define

define factor
    [number]
    |    [stringlit]
    |    [set]
    |    [designator] [opt ActualParameters]
    |    ( [expression] )
    |    NOT [factor]
end define

define set
    [opt qualident] { [list element] }
end define

define element
    [expression] [opt dotdot_expression]
end define

define dotdot_expression
    .. [expression]
end define

define ActualParameters
    ( [opt ExpList] )
end define

define statement
    [assignment]
    |    [ProcedureCall]
    |    [IfStatement]
    |    [CaseStatement]
    |    [WhileStatement]
    |    [RepeatStatement]
    |    [LoopStatement]
    |    [ForStatement]
    |    [WithStatement]
    |    EXIT
    |    RETURN [opt expression]
end define

define assignment
    [designator] := [expression]
end define

define ProcedureCall
    [designator] [opt ActualParameters]
end define

define StatementSequence
    [statement] [repeat semi_statement] [opt ';]    [NL]
end define

define semi_statement
    ;         [NL]
    [statement]
end define

define IfStatement
    IF [expression] THEN        [IN][NL]
        [StatementSequence]        [EX]
    [repeat elsif_clause]
    [opt else_StatementSequence]
    END
end define

define elsif_clause
    ELSIF [expression] THEN     [IN][NL]
        [StatementSequence]        [EX]
end define

define else_StatementSequence
    ELSE                 [IN][NL]
        [StatementSequence]        [EX]
end define

define CaseStatement
    CASE [expression] OF            [IN][NL]
        [case]
        [repeat or_case]
        [opt else_StatementSequence]    [EX]
    END
end define

define or_case
    '| [case]
end define

define case
    [CaseLabelList] :     [IN][NL]
        [StatementSequence]    [EX]
end define

define WhileStatement
    WHILE [expression] DO    [IN][NL]
        [StatementSequence]    [EX]
    END
end define

define RepeatStatement
    REPEAT            [IN][NL]
        [StatementSequence]    [EX]
    UNTIL [expression]
end define

define ForStatement
    FOR [id] := [expression] TO [expression] [opt by_ConstExpression] DO    [IN][NL]
        [StatementSequence]    [EX]
    END
end define

define by_ConstExpression
    BY [ConstExpression]
end define

define LoopStatement
    LOOP            [IN][NL]
        [StatementSequence]    [EX]
    END
end define

define WithStatement
    WITH [designator] DO    [IN][NL]
        [StatementSequence]    [EX]
    END
end define

define ProcedureDeclaration
                [NL]
    [ProcedureHeading] ;
    [block] [id]
end define

define ProcedureHeading
    PROCEDURE [id] [opt FormalParameters]
end define

define block
                [NL]
    [repeat declaration]
    BEGIN            [IN][NL]
        [StatementSequence]    [EX]
    END
end define

define declaration
    CONST                     [IN][NL]
        [repeat ConstantDeclaration_semi]    [EX]
    |    TYPE                     [IN][NL]
        [repeat TypeDeclaration_semi]    [EX]
    |    VAR                     [IN][NL]
        [repeat VariableDeclaration_semi]    [EX]
    |    [ProcedureDeclaration] ;        [NL][NL]
    |    [ModuleDeclaration] ;            [NL][NL]
end define

define ConstantDeclaration_semi
    [ConstantDeclaration] ;    [NL]
end define

define TypeDeclaration_semi
    [TypeDeclaration] ;    [NL]
end define

define VariableDeclaration_semi
    [VariableDeclaration] ;    [NL]
end define

define FormalParameters
    ( [FPSection] [repeat semi_FPSection] ) [opt ProcedureResult]
end define

define semi_FPSection
    ; [FPSection]
end define

define FPSection
    [opt 'VAR] [IdentList] : [FormalType]
end define

define FormalType
    [opt array_of] [qualident]
end define

define ProcedureResult
    : [qualident]
end define

define array_of
    ARRAY OF
end define

define ModuleDeclaration
                    [NL]
    MODULE [id] [opt priority] ;    [NL][NL]
        [repeat import]
        [opt export]
        [block] [id] ;        [NL]
end define

define priority
    '[ [ConstExpression] ']
end define

define export
    EXPORT [opt 'QUALIFIED] [IdentList] ;    [NL]
end define

define import
    [opt from_ident] IMPORT [IdentList] ;    [NL]
end define

define from_ident
    FROM [id]
end define

define DefinitionModule
                    [NL]
    DEFINITION MODULE [id] ;    [NL][NL]
        [repeat import]
        [repeat definition]
    END [id] .            [NL]
end define

define definition
    CONST                     [IN][NL]
        [repeat ConstantDeclaration_semi]    [EX]
    |    TYPE                     [IN][NL]
        [repeat TypeDeclaration_semi]    [EX]
    |    VAR                     [IN][NL]
        [repeat VariableDeclaration_semi]    [EX]
    |    [ProcedureHeading] ;            [NL]
end define

define ProgramModule
    MODULE [id] [opt priority] ;    [NL][NL]
        [repeat import]
        [block] [id] .
end define

define CompilationUnit
    [DefinitionModule]
    |    [opt 'IMPLEMENTATION] [ProgramModule]
end define