#|[
Author: Juergen Lorenz
ju (at) jugilo (dot) de

Copyright (c) 2014-2019, Juergen Lorenz
All rights reserved.

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modification, are permitted provided that the following conditions are
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used to endorse or promote products derived from this software without
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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]|#


(module simple-exceptions
  (simple-exceptions exception? exception-of? make-exception
   assert-exception argument-exception result-exception
   exn? exn-of? make-exn argument-exn result-exn assert-exn
   location message arguments raise with-exn-handler guard)

  (import scheme (only (chicken base) assert void print case-lambda error)
                 (chicken condition)
                 (chicken module)
                 (chicken continuation))
  (reexport (only (chicken condition)
                  current-exception-handler
                  handle-exceptions
                  condition-case))

;;; (exception? xpr)
;;; ----------------
;;; type predicate
(define (exception? xpr)
  (and (condition? xpr)
       ((condition-predicate 'exn) xpr)))

;;; (exception-of? kind-key)
;;; ------------------------
;;; returns a predicate which checks, if its argument is an exception of
;;; kind kind-key
(define (exception-of? kind-key)
  (lambda (xpr)
    (and (exception? xpr)
         ((condition-predicate kind-key) xpr))))


;;; (make-exception msg . kind-keys)
;;; ---------------------------------
;;; returns a procedure with arguments loc and args
;;; to construct composite-conditions of kind 'exn and kind-keys.
;;; Note, that msg and kind-keys are independent of a concrete use of
;;; this exception, while loc and args depend exactly on that use.
(define (make-exception msg . kind-keys)
  (lambda (loc . args)
    (if (null? kind-keys)
      (make-property-condition 'exn 
                               'location loc
                               'message msg
                               'arguments args)
      (apply make-composite-condition
             (make-property-condition 'exn 
                                      'location loc
                                      'message msg
                                      'arguments args)
             (map (lambda (kind) (make-property-condition kind))
                  kind-keys)))))

;;; exceptions
;;; ----------
(define argument-exception
  (make-exception "precondition violated" 'argument))
(define result-exception
  (make-exception "postcondition violated" 'result))
(define assert-exception
  (make-exception "assertion violated" 'assert))

;;;; some aliases
(define exn? exception?)
(define exn-of? exception-of?)
(define make-exn make-exception)
(define argument-exn argument-exception)
(define result-exn result-exception)
(define assert-exn assert-exception)

;;; (guard (exn cond-clause . cond-clauses) xpr . xprs)
;;; ---------------------------------------------------
;;; R6RS and R7RS high-level exception-handler
(define-syntax guard
  (syntax-rules ()
    ((_ (exn cond-clause . cond-clauses) xpr . xprs)
     (handle-exceptions exn (cond cond-clause . cond-clauses)
                        xpr . xprs))))
;;; (location exn)
;;; --------------
;;; returns the location property of its exception argument
(define (location exn)
  (assert (exception? exn)
    'location "assertion failed" '(exception?  exn))
  (get-condition-property exn 'exn 'location 'unknown))

;;; (message exn)
;;; -------------
;;; returns the message property of its exception argument
(define (message exn)
  (assert (exception? exn)
    'message "assertion failed" '(exception?  exn))
  (get-condition-property exn 'exn 'message "no message supplied"))

;;; (arguments exn)
;;; ---------------
;;; returns the arguments property of its exception argument
(define (arguments exn)
  (assert (exception? exn)
    'arguments "assertion failed" '(exception?  exn))
  (get-condition-property exn 'exn 'arguments '()))

(define (##sys#raise x)
  (##sys#current-exception-handler x)
  (##sys#abort
   (##sys#make-structure
    'condition
    '(exn)
    (list '(exn . message)"exception handler returned"
          '(exn . arguments) (arguments x)
          '(exn . location) (location x)))))

;;; (raise exn)
;;; -----------
;;; raises a non-continuable exception
(define (raise exn)
  (if (exception? exn)
    (##sys#raise exn)
    ;(##sys#abort exn)))
    (abort exn)))

;;; (with-exn-handler handler thunk)
;;; ----------------------------
;;; wrapping Chicken's with-exception-handler into pop-and-call
;;; to avoid the generation of infinite loops
(define (with-exn-handler handler thunk)
  ((call-with-current-continuation
     (lambda (k)
       (with-exception-handler ; Chicken's handler
         (lambda (exn)
           (k (lambda () (handler exn))))
         thunk)))))

;;; (simple-exceptions [sym])
;;; -------------------------
;;; documentation procedure
(define simple-exceptions
  (let ((als '(
    (simple-exceptions
      procedure:
      (simple-exceptions sym ..)
      "documentation procedure")
    (exception?
      procedure:
      (exception? xpr)
      "type predicate")
    (exn?
      procedure:
      (exn? xpr)
      "alias to exception?")
    (exception-of?
      procedure:
      (exception-of? kind-key)
      "returns a predicate which checks, if its argument"
      "is an exception of kind kind-key")
    (exn-of?
      procedure:
      (exn-of? kind-key)
      "alias to exception-of?")
    (make-exception
      procedure:
      (make-exception msg . kind-keys)
      "returns a procedure with arguments loc and args"
      "Note, that msg and kind-keys are independent of a concrete use of"
      "this exception, while loc and args depend exactly on that use.")
    (make-exn
      procedure:
      (make-exn msg . kind-keys)
      "alias to make-exception")
    (location
      procedure:
      (location exn)
      "returns the location property of its exception argument")
    (message
      procedure:
      (message exn)
      "returns the message property of its exception argument")
    (arguments
      procedure:
      (arguments exn)
      "returns the arguments property of its exception argument")
    (raise
      procedure:
      (raise exn)
      "raises a non-continuable exception")
    (with-exn-handler
      procedure:
      (with-exn-handler handler thunk)
      "wraps Chicken's with-exception-handler into pop-and-call"
      "to avoid the generation of infinite loops")
    (guard
      macro:
      (guard (exn cond-clause . cond-clauses) xpr . xprs)
      "R6RS and R7RS high-level exception-handler")
    (handle-exception
      macro:
      (handle-exceptions exn handle-xpr xpr . xprs)
      "reexport of Chicken's routine")
    (condition-case
      macro:
      (condition-case xpr ([var] (kind ...) body) . other-clauses)
      "reexport of Chicken's macro")
    (argument-exception
      exception:
      (argument-exception loc arg ...)
      "raised when a precondition is violated"
      "catched with (exn argument)")
    (argument-exn
      exception:
      (argument-exn loc arg ...)
      "alias to argument-exception")
    (result-exception
      exception:
      (result-exception loc arg ...)
      "raised when a postcondition is violated"
      "catched with (exn result)")
    (result-exn
      exception:
      (result-exn loc arg ...)
      "alias to result-exception")
    (assert-exception
      exception:
      (assert-exception loc arg ...)
      "raised when an assertion is violated"
      "catched with (exn assert)")
    (assert-exn
      exception:
      (assert-exn loc arg ...)
      "alias to assert-exception")
    )))
    (case-lambda
      (()
       (map car als))
      ((sym)
       (let ((pair (assq sym als)))
         (if pair
           (for-each print (cdr pair))
           (error "Not in list"
                  sym
                  (map car als))))))))

) ; module simple-exceptions