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;;; -*- Mode: Lisp; Syntax: Common-Lisp; Package: "CONDITIONS"; Base: 10 -*-
(IN-PACKAGE "CONDITIONS")
(DEFVAR *HANDLER-CLUSTERS* NIL)
(DEFMACRO HANDLER-BIND (BINDINGS &BODY FORMS)
(UNLESS (EVERY #'(LAMBDA (X) (AND (LISTP X) (= (LENGTH X) 2))) BINDINGS)
(ERROR "Ill-formed handler bindings."))
`(LET ((*HANDLER-CLUSTERS* (CONS (LIST ,@(MAPCAR #'(LAMBDA (X) `(CONS ',(CAR X) ,(CADR X)))
BINDINGS))
*HANDLER-CLUSTERS*)))
,@FORMS))
(DEFVAR *BREAK-ON-SIGNALS* NIL)
(DEFUN SIGNAL (DATUM &REST ARGUMENTS)
(LET ((CONDITION (COERCE-TO-CONDITION DATUM ARGUMENTS 'SIMPLE-CONDITION 'SIGNAL))
(*HANDLER-CLUSTERS* *HANDLER-CLUSTERS*))
(IF (TYPEP CONDITION *BREAK-ON-SIGNALS*)
(BREAK "~A~%Break entered because of *BREAK-ON-SIGNALS*."
CONDITION))
(LOOP (IF (NOT *HANDLER-CLUSTERS*) (RETURN))
(LET ((CLUSTER (POP *HANDLER-CLUSTERS*)))
(DOLIST (HANDLER CLUSTER)
(WHEN (TYPEP CONDITION (CAR HANDLER))
(FUNCALL (CDR HANDLER) CONDITION)
(RETURN NIL) ;?
))))
NIL))
;;; COERCE-TO-CONDITION
;;; Internal routine used in ERROR, CERROR, BREAK, and WARN for parsing the
;;; hairy argument conventions into a single argument that's directly usable
;;; by all the other routines.
(DEFUN COERCE-TO-CONDITION (DATUM ARGUMENTS DEFAULT-TYPE FUNCTION-NAME)
#+LISPM (SETQ ARGUMENTS (COPY-LIST ARGUMENTS))
(COND ((CONDITIONP DATUM)
(IF ARGUMENTS
(CERROR "Ignore the additional arguments."
'SIMPLE-TYPE-ERROR
:DATUM ARGUMENTS
:EXPECTED-TYPE 'NULL
:FORMAT-STRING "You may not supply additional arguments ~
when giving ~S to ~S."
:FORMAT-ARGUMENTS (LIST DATUM FUNCTION-NAME)))
DATUM)
((OR (SYMBOLP DATUM) (CONDITION-CLASS-P DATUM))
(APPLY #'MAKE-CONDITION DATUM ARGUMENTS))
((STRINGP DATUM)
(MAKE-CONDITION DEFAULT-TYPE
:FORMAT-STRING DATUM
:FORMAT-ARGUMENTS ARGUMENTS))
(T
(ERROR 'SIMPLE-TYPE-ERROR
:DATUM DATUM
:EXPECTED-TYPE '(OR SYMBOL STRING)
:FORMAT-STRING "Bad argument to ~S: ~S"
:FORMAT-ARGUMENTS (LIST FUNCTION-NAME DATUM)))))
(DEFUN ERROR (DATUM &REST ARGUMENTS)
(LET ((CONDITION (COERCE-TO-CONDITION DATUM ARGUMENTS 'SIMPLE-ERROR 'ERROR)))
(SIGNAL CONDITION)
(INVOKE-DEBUGGER CONDITION)))
(DEFUN CERROR (CONTINUE-STRING DATUM &REST ARGUMENTS)
(WITH-SIMPLE-RESTART (CONTINUE "~A" (APPLY #'FORMAT NIL CONTINUE-STRING ARGUMENTS))
(APPLY #'ERROR DATUM ARGUMENTS))
NIL)
(DEFUN BREAK (&OPTIONAL (FORMAT-STRING "Break") &REST FORMAT-ARGUMENTS)
(WITH-SIMPLE-RESTART (CONTINUE "Return from BREAK.")
(INVOKE-DEBUGGER
(MAKE-CONDITION 'SIMPLE-CONDITION
:FORMAT-STRING FORMAT-STRING
:FORMAT-ARGUMENTS FORMAT-ARGUMENTS)))
NIL)
(DEFUN WARN (DATUM &REST ARGUMENTS)
(LET ((CONDITION
(COERCE-TO-CONDITION DATUM ARGUMENTS 'SIMPLE-WARNING 'WARN)))
(CHECK-TYPE CONDITION WARNING "a warning condition")
(IF *BREAK-ON-WARNINGS*
(BREAK "~A~%Break entered because of *BREAK-ON-WARNINGS*."
CONDITION))
(RESTART-CASE (SIGNAL CONDITION)
(MUFFLE-WARNING ()
:REPORT "Skip warning."
(RETURN-FROM WARN NIL)))
(FORMAT *ERROR-OUTPUT* "~&Warning:~%~A~%" CONDITION)
NIL))
(DEFMACRO HANDLER-CASE (FORM &REST CASES)
(LET ((NO-ERROR-CLAUSE (ASSOC ':NO-ERROR CASES)))
(IF NO-ERROR-CLAUSE
(LET ((NORMAL-RETURN (MAKE-SYMBOL "NORMAL-RETURN"))
(ERROR-RETURN (MAKE-SYMBOL "ERROR-RETURN")))
`(BLOCK ,ERROR-RETURN
(MULTIPLE-VALUE-CALL #'(LAMBDA ,@(CDR NO-ERROR-CLAUSE))
(BLOCK ,NORMAL-RETURN
(RETURN-FROM ,ERROR-RETURN
(HANDLER-CASE (RETURN-FROM ,NORMAL-RETURN ,FORM)
,@(REMOVE NO-ERROR-CLAUSE CASES)))))))
(LET ((TAG (GENSYM))
(VAR (GENSYM))
(ANNOTATED-CASES (MAPCAR #'(LAMBDA (CASE) (CONS (GENSYM) CASE))
CASES)))
`(BLOCK ,TAG
(LET ((,VAR NIL))
,VAR ;ignorable
(TAGBODY
(HANDLER-BIND ,(MAPCAR #'(LAMBDA (ANNOTATED-CASE)
(LIST (CADR ANNOTATED-CASE)
`#'(LAMBDA (TEMP)
,@(IF (CADDR ANNOTATED-CASE)
`((SETQ ,VAR TEMP)))
(GO ,(CAR ANNOTATED-CASE)))))
ANNOTATED-CASES)
(RETURN-FROM ,TAG ,FORM))
,@(MAPCAN #'(LAMBDA (ANNOTATED-CASE)
(LIST (CAR ANNOTATED-CASE)
(LET ((BODY (CDDDR ANNOTATED-CASE)))
`(RETURN-FROM ,TAG
,(COND ((CADDR ANNOTATED-CASE)
`(LET ((,(CAADDR ANNOTATED-CASE)
,VAR))
,@BODY))
((NOT (CDR BODY))
(CAR BODY))
(T
`(PROGN ,@BODY)))))))
ANNOTATED-CASES))))))))
(DEFMACRO IGNORE-ERRORS (&REST FORMS)
`(HANDLER-CASE (PROGN ,@FORMS)
(ERROR (CONDITION) (VALUES NIL CONDITION))))
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