libobjc/objc/objc-exception.h

   1 /* GNU Objective C Runtime native exceptions
   2    Copyright (C) 2010-2018 Free Software Foundation, Inc.
   3    Contributed by Nicola Pero <nicola.pero@meta-innovation.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 #ifndef __objc_exception_INCLUDE_GNU
  27 #define __objc_exception_INCLUDE_GNU
  28
  29 #include "objc.h"
  30 #include "objc-decls.h"
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36 /* 'objc_exception_throw' throws the exception 'exception', which is
  37    an exception object.
  38
  39    Calls to 'objc_exception_throw' are automatically generated by the
  40    compiler: an Objective-C "@throw exception;" statement gets
  41    compiled into the equivalent of "objc_exception_throw
  42    (exception);".
  43
  44    'objc_exception_throw' searches for a @catch() that can catch the
  45    exception.  By default, @catch (MyClass object) will catch all
  46    exception objects that are of class MyClass or of a subclass of
  47    MyClass; if the exception object is 'nil', then the exception can
  48    only be caught with a catch-all exception handler where no
  49    exception class is specified (such as @catch(id object)).  This
  50    behaviour can be customized by setting an 'objc_exception_matcher'
  51    function (using objc_set_exception_matcher(), see below); if one is
  52    set, it is used instead of the default one.
  53
  54    If the exception is uncaught (there is no @catch() to catch it),
  55    the program aborts.  It is possible to customize this behaviour by
  56    setting an 'objc_uncaught_exception_handler' function (using
  57    objc_set_uncaught_exception_handler(), see below); if one is set,
  58    it is executed before abort() is called.  An uncaught exception
  59    handler is expected to never return.  */
  60 objc_EXPORT void objc_exception_throw (id exception);
  61
  62 /* Compatibility note: the Apple/NeXT runtime seems to also have
  63    objc_exception_rethrow(), objc_begin_catch() and objc_end_catch().
  64    Currently the GNU runtime does not use them.  */
  65
  66 /* The following functions allow customizing to a certain extent the
  67    exception handling.  They are not thread safe and should be called
  68    during the program initialization before threads are started.  They
  69    are mostly reserved for "Foundation" libraries; in the case of
  70    GNUstep, GNUstep Base may be using these functions to improve the
  71    standard exception handling.  You probably shouldn't use these
  72    functions unless you are writing your own Foundation library.  */
  73
  74 /* Compatibility note: objc_set_exception_preprocessor() (available on
  75    the Apple/NeXT runtime) is not available on the GNU runtime.  */
  76
  77 /* An 'objc_exception_matcher' function is used to match an exception
  78    to a @catch clause.  'catch_class' is the class of objects caught
  79    by the @catch clause (for example, in "@catch (Object *o)", the
  80    catch_class is Object).  It should return 1 if the exception should
  81    be caught by a @catch with a catch_class argument, and 0 if
  82    not.  */
  83 typedef int (*objc_exception_matcher)(Class catch_class, id exception);
  84
  85 /* Sets a new exception matcher function, and returns the previous
  86    exception matcher function.  This function is not safe to call in a
  87    multi-threaded environment because other threads may be trying to
  88    invoke the exception matcher while you change it!  */
  89 objc_EXPORT objc_exception_matcher
  90 objc_setExceptionMatcher (objc_exception_matcher new_matcher);
  91
  92
  93 /* An 'objc_uncaught_exception_handler' function is a function that
  94    handles uncaught exceptions.  It should never return.  */
  95 typedef void (*objc_uncaught_exception_handler)(id exception);
  96
  97 /* Sets a new uncaught exception handler function, and returns the
  98    previous exception handler function.  This function is not safe to
  99    call in a multi-threaded environment because other threads may be
 100    trying to invoke the uncaught exception handler while you change
 101    it.  */
 102 objc_EXPORT objc_uncaught_exception_handler
 103 objc_setUncaughtExceptionHandler (objc_uncaught_exception_handler new_handler);
 104
 105 #ifdef __cplusplus
 106 }
 107 #endif
 108
 109 #endif /* not __objc_exception_INCLUDE_GNU */