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(define-module (ice-9 exceptions) |
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#:re-export (&exception |
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make-exception |
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make-exception-type |
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simple-exceptions |
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exception? |
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exception-type? |
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exception-predicate |
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exception-accessor |
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exception-kind |
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exception-args |
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&error |
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&programming-error |
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&quit-exception |
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&non-continuable |
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raise-exception |
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with-exception-handler) |
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#:export (define-exception-type |
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&message |
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make-exception-with-message |
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exception-with-message? |
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exception-message |
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&warning |
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make-warning |
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warning? |
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make-error |
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error? |
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&external-error |
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make-external-error |
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external-error? |
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make-quit-exception |
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quit-exception? |
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make-programming-error |
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programming-error? |
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&assertion-failure |
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make-assertion-failure |
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assertion-failure? |
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&irritants |
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make-exception-with-irritants |
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exception-with-irritants? |
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exception-irritants |
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&origin |
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make-exception-with-origin |
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exception-with-origin? |
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exception-origin |
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make-non-continuable-error |
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non-continuable-error? |
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&implementation-restriction |
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make-implementation-restriction-error |
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implementation-restriction-error? |
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&lexical |
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make-lexical-error |
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lexical-error? |
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&syntax |
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make-syntax-error |
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syntax-error? |
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syntax-error-form |
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syntax-error-subform |
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&undefined-variable |
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make-undefined-variable-error |
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undefined-variable-error? |
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raise-continuable |
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guard)) |
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(define-syntax define-exception-type-procedures |
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(syntax-rules () |
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((_ exception-type supertype constructor predicate |
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(field accessor) ...) |
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(begin |
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(define constructor (record-constructor exception-type)) |
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(define predicate (exception-predicate exception-type)) |
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(define accessor |
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(exception-accessor exception-type |
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(record-accessor exception-type 'field))) |
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...)))) |
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(define-syntax define-exception-type |
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(syntax-rules () |
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((_ exception-type supertype constructor predicate |
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(field accessor) ...) |
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(begin |
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(define exception-type |
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(make-record-type 'exception-type '((immutable field) ...) |
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#:parent supertype #:extensible? #t)) |
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(define-exception-type-procedures exception-type supertype |
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constructor predicate (field accessor) ...))))) |
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(define-exception-type-procedures &error &exception |
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make-error error?) |
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(define-exception-type-procedures &programming-error &error |
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make-programming-error programming-error?) |
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(define-exception-type &assertion-failure &programming-error |
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make-assertion-failure assertion-failure?) |
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(define-exception-type &message &exception |
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make-exception-with-message exception-with-message? |
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(message exception-message)) |
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(define-exception-type &warning &exception |
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make-warning warning?) |
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(define-exception-type &external-error &error |
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make-external-error external-error?) |
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(define-exception-type &irritants &exception |
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make-exception-with-irritants exception-with-irritants? |
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(irritants exception-irritants)) |
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(define-exception-type &origin &exception |
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make-exception-with-origin exception-with-origin? |
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(origin exception-origin)) |
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(define-exception-type-procedures &non-continuable &programming-error |
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make-non-continuable-error |
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non-continuable-error?) |
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(define-exception-type &implementation-restriction &programming-error |
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make-implementation-restriction-error |
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implementation-restriction-error?) |
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(define-exception-type &lexical &programming-error |
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make-lexical-error lexical-error?) |
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(define-exception-type &syntax &programming-error |
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make-syntax-error syntax-error? |
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(form syntax-error-form) |
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(subform syntax-error-subform)) |
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(define-exception-type &undefined-variable &programming-error |
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make-undefined-variable-error undefined-variable-error?) |
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(define make-exception-with-kind-and-args |
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(record-constructor &exception-with-kind-and-args)) |
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(define make-quit-exception |
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(record-constructor &quit-exception)) |
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(define quit-exception? |
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(exception-predicate &quit-exception)) |
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(define (default-guile-exception-converter key args) |
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(make-exception (make-error) |
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(guile-common-exceptions key args))) |
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(define (guile-common-exceptions key args) |
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(apply (case-lambda |
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((subr msg margs . _) |
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(make-exception |
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(make-exception-with-origin subr) |
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(make-exception-with-message msg) |
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(make-exception-with-irritants margs))) |
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(_ (make-exception-with-irritants args))) |
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args)) |
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(define (convert-guile-exception key args) |
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(let ((converter (assv-ref guile-exception-converters key))) |
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(make-exception (or (and converter (converter key args)) |
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(default-guile-exception-converter key args)) |
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(make-exception-with-kind-and-args key args)))) |
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(define (raise-continuable obj) |
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(raise-exception obj #:continuable? #t)) |
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(define (exception-printer port key args punt) |
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(cond ((and (= 1 (length args)) |
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(exception? (car args))) |
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(display "ERROR:\n" port) |
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(format-exception port (car args))) |
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(else |
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(punt)))) |
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(define (format-exception port exception) |
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(let ((components (simple-exceptions exception))) |
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(if (null? components) |
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(format port "Empty exception object") |
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(let loop ((i 1) (components components)) |
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(cond ((pair? components) |
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(format port " ~a. " i) |
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(format-simple-exception port (car components)) |
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(when (pair? (cdr components)) |
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(newline port)) |
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(loop (+ i 1) (cdr components)))))))) |
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(define (format-simple-exception port exception) |
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(let* ((type (struct-vtable exception)) |
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(name (record-type-name type)) |
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(fields (record-type-fields type))) |
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(cond |
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((null? fields) |
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(format port "~a" name)) |
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((null? (cdr fields)) |
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(format port "~a: ~s" name (struct-ref exception 0))) |
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(else |
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(format port "~a:\n" name) |
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(let lp ((fields fields) (i 0)) |
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(let ((field (car fields)) |
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(fields (cdr fields))) |
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(format port " ~a: ~s" field (struct-ref exception i)) |
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(unless (null? fields) |
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(newline port) |
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(lp fields (+ i 1))))))))) |
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(set-exception-printer! '%exception exception-printer) |
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(define (guile-syntax-error-converter key args) |
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(apply (case-lambda |
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((who what where form subform . extra) |
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(make-exception (make-syntax-error form subform) |
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(make-exception-with-origin who) |
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(make-exception-with-message what))) |
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(_ #f)) |
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args)) |
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(define make-quit-exception (record-constructor &quit-exception)) |
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(define (guile-quit-exception-converter key args) |
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(define code |
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(cond |
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((not (pair? args)) 0) |
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((integer? (car args)) (car args)) |
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((not (car args)) 1) |
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(else 0))) |
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(make-exception (make-quit-exception code) |
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(guile-common-exceptions key args))) |
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(define (guile-lexical-error-converter key args) |
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(make-exception (make-lexical-error) |
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(guile-common-exceptions key args))) |
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(define (guile-assertion-failure-converter key args) |
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(make-exception (make-assertion-failure) |
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(guile-common-exceptions key args))) |
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(define (guile-undefined-variable-error-converter key args) |
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(make-exception (make-undefined-variable-error) |
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(guile-common-exceptions key args))) |
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(define (guile-implementation-restriction-converter key args) |
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(make-exception (make-implementation-restriction-error) |
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(guile-common-exceptions key args))) |
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(define (guile-external-error-converter key args) |
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(make-exception (make-external-error) |
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(guile-common-exceptions key args))) |
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(define (guile-system-error-converter key args) |
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(apply (case-lambda |
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((subr msg msg-args errno . rest) |
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(make-exception (make-external-error) |
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(guile-common-exceptions key args))) |
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(_ (guile-external-error-converter key args))) |
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args)) |
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(define guile-exception-converters |
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`((quit . ,guile-quit-exception-converter) |
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(read-error . ,guile-lexical-error-converter) |
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(syntax-error . ,guile-syntax-error-converter) |
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(unbound-variable . ,guile-undefined-variable-error-converter) |
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(wrong-number-of-args . ,guile-assertion-failure-converter) |
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(wrong-type-arg . ,guile-assertion-failure-converter) |
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(keyword-argument-error . ,guile-assertion-failure-converter) |
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(out-of-range . ,guile-assertion-failure-converter) |
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(regular-expression-syntax . ,guile-assertion-failure-converter) |
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(program-error . ,guile-assertion-failure-converter) |
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(goops-error . ,guile-assertion-failure-converter) |
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(null-pointer-error . ,guile-assertion-failure-converter) |
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(system-error . ,guile-system-error-converter) |
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(host-not-found . ,guile-external-error-converter) |
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(getaddrinfo-error . ,guile-external-error-converter) |
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(no-data . ,guile-external-error-converter) |
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(no-recovery . ,guile-external-error-converter) |
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(try-again . ,guile-external-error-converter) |
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(stack-overflow . ,guile-implementation-restriction-converter) |
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(numerical-overflow . ,guile-implementation-restriction-converter) |
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(memory-allocation-error . ,guile-implementation-restriction-converter))) |
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(define (set-guile-exception-converter! key proc) |
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(set! guile-exception-converters |
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(acons key proc guile-exception-converters))) |
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(set! make-exception-from-throw convert-guile-exception) |
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(define-syntax guard |
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(lambda (stx) |
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"Establish an exception handler during the evaluation of an expression. |
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@example |
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(guard (@var{exn} @var{clause1} @var{clause2} ...) |
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@var{body} @var{body*} ...) |
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@end example |
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Each @var{clause} should have the same form as a @code{cond} clause. |
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The @code{(begin body body* ...)} is evaluated with an exception |
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handler that binds the raised object to @var{exn} and within the scope of |
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that binding evaluates the clauses as if they were the clauses of a cond |
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expression. |
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When a clause of that implicit cond expression matches, its consequent |
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is evaluated with the continuation and dynamic environment of the |
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@code{guard} expression. |
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If every clause's test evaluates to false and there is no @code{else} |
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clause, then @code{raise-continuable} is re-invoked on the raised |
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object, within the dynamic environment of the original call to raise |
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except that the current exception handler is that of the guard |
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expression. |
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Note that in a slight deviation from SRFI-34, R6RS, and R7RS, Guile |
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evaluates the clause tests within the continuation of the exception |
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handler, not the continuation of the @code{guard}. This allows |
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unhandled exceptions to continue to dispatch within the original |
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continuation, without unwinding then rewinding any intermediate |
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@code{dynamic-wind} invocations." |
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(define (dispatch tag exn clauses) |
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(define (build-clause test handler clauses) |
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#`(let ((t #,test)) |
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(if t |
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(abort-to-prompt #,tag #,handler t) |
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#,(dispatch tag exn clauses)))) |
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(syntax-case clauses (=> else) |
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(() #`(raise-continuable #,exn)) |
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(((test => f) . clauses) |
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(build-clause #'test #'(lambda (res) (f res)) #'clauses)) |
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(((else e e* ...) . clauses) |
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(build-clause #'#t #'(lambda (res) e e* ...) #'clauses)) |
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(((test) . clauses) |
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(build-clause #'test #'(lambda (res) res) #'clauses)) |
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(((test e* ...) . clauses) |
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(build-clause #'test #'(lambda (res) e* ...) #'clauses)))) |
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(syntax-case stx () |
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((guard (exn clause clause* ...) body body* ...) |
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(identifier? #'exn) |
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#`(let ((tag (make-prompt-tag))) |
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(call-with-prompt |
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tag |
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(lambda () |
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(with-exception-handler |
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(lambda (exn) |
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#,(dispatch #'tag #'exn #'(clause clause* ...))) |
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(lambda () body body* ...))) |
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(lambda (_ h v) |
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(h v)))))))) |
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