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;;; File: parser/typedecl-parser Author: John
(define (parse-type-decl interface?)
(save-parser-context
(let* ((sig (parse-signature))
(contexts (signature-context sig))
(simple (signature-type sig))
(deriving '())
(constrs '()))
;; #t = builtins ([] (,,) ->) not allowed
(check-simple simple '#t "type declaration")
(let ((annotations (parse-constr-annotations)))
(token-case
(= (setf constrs (parse-constrs))
(token-case
(|deriving|
(setf deriving
(token-case
(\(
(token-case
(\) '())
(else (parse-class-list))))
(tycon (list (class->ast)))
(else (signal-invalid-syntax "a deriving clause")))))))
(else
(when (not interface?)
(signal-missing-constructors))))
(make data-decl (context contexts) (simple simple)
(constrs constrs) (deriving deriving)
(annotations annotations))))))
(define (signal-missing-constructors)
(parser-error 'missing-constructors
"Data type definition requires constructors"))
(define (check-simple simple fresh? where)
(when (not (tycon? simple))
(signal-not-simple where))
(when (and fresh? (not (eq? (tycon-def simple) *undefined-def*)))
(signal-not-simple where))
(let ((tyvars (map (lambda (arg)
(when (not (tyvar? arg))
(signal-not-simple where))
(tyvar-name arg))
(tycon-args simple))))
(when (not (null? (find-duplicates tyvars)))
(signal-unique-tyvars-required))))
(define (signal-unique-tyvars-required)
(parser-error 'unique-tyvars-required
"Duplicate type variables appear in simple."))
(define (signal-not-simple where)
(parser-error 'not-simple "Simple type required in ~a." where))
(define (parse-constrs)
(let ((constr (parse-constr)))
(token-case
(\| (cons constr (parse-constrs)))
(else (list constr)))))
(define (parse-constr)
(save-parser-context
(let ((saved-excursion (save-scanner-state)))
(token-case
(consym/paren
(parse-prefix-constr))
(else
(let ((type1 (parse-btype))
(anns (parse-constr-annotations)))
(token-case
(conop
(parse-infix-constr (tuple type1 anns)))
(else
(restore-excursion saved-excursion)
(parse-prefix-constr)))))))))
(define (parse-prefix-constr)
(token-case
(con
(let* ((con (con->ast))
(types (parse-constr-type-list)))
(make constr (constructor con) (types types))))
(else
(signal-missing-token "<con>" "constrs list"))))
(define (parse-constr-type-list)
(token-case
(atype-start
(let* ((atype (parse-atype))
(anns (parse-constr-annotations)))
(cons (tuple atype anns)
(parse-constr-type-list))))
(else '())))
(define (parse-infix-constr t+a1)
(let* ((con (conop->ast))
(type2 (parse-btype))
(anns (parse-constr-annotations)))
(make constr (constructor con) (types (list t+a1 (tuple type2 anns))))))
(define (parse-class-list)
(token-case
(tycon (let ((class (class->ast)))
(token-case
(\, (cons class (parse-class-list)))
(\) (list class))
(else (signal-missing-token "`)' or `,'" "deriving clause")))))
(else (signal-missing-token "<tycon>" "deriving clause"))))
(define (parse-constr-annotations)
(token-case
((begin-annotation no-advance)
(let ((annotations (parse-annotations)))
(append annotations (parse-constr-annotations))))
(else '())))
(define (parse-synonym-decl)
(save-parser-context
(let* ((sig (parse-signature))
(contexts (signature-context sig))
(simple (signature-type sig)))
(check-simple simple '#t "type synonym declaration")
(when (not (null? contexts))
(signal-no-context-in-synonym))
(require-token = (signal-missing-token "`='" "type synonym declaration"))
(let ((body (parse-type)))
(make synonym-decl (simple simple) (body body))))))
(define (signal-no-context-in-synonym)
(parser-error 'no-context-in-synonym
"Context is not permitted in type synonym declaration."))
(define (parse-class-decl)
(save-parser-context
(let ((supers (parse-optional-context)))
(token-case
(tycon
(let ((class (class->ast)))
(token-case
(tyvar
(let* ((class-var (token->symbol))
(decls (parse-where-decls)))
(make class-decl (class class) (super-classes supers)
(class-var class-var) (decls decls))))
(else
(signal-missing-token "<tyvar>" "class declaration")))))
(else (signal-missing-token "<tycon>" "class declaration"))))))
(define (parse-instance-decl interface?)
(save-parser-context
(let ((contexts (parse-optional-context))
(decls '()))
(token-case
(tycon
(let* ((class (class->ast))
(simple (parse-type)))
(when (not interface?)
(setf decls (parse-where-decls)))
(check-simple simple '#f "instance declaration")
(make instance-decl (context contexts) (class class)
(simple simple) (decls decls))))
(else (signal-missing-token "<tycon>" "instance declaration"))))))
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