(reset_var_on_error): New fun.
(signal_before_change, signal_after_change): Use it to reset (after|before)-change-functions to nil in case of error. Bind inhibit-modification-hooks to t. Don't bind (after|before)-change-functions to nil while they run.
This commit is contained in:
Stefan Monnier
parent
d5dac3b9bd
commit
97c4ef2a20
4 changed files with 57 additions and 90 deletions
5
etc/NEWS
5
etc/NEWS
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@ -79,6 +79,11 @@ in to make it use the scrollbars from the system theme.
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* Lisp Changes in Emacs 22.2.
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+++
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** inhibit-modification-hooks is bound to t while running modification hooks.
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As a happy consequence, after-change-functions and before-change-functions
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are not bound to nil any more while running an (after|before)-change-function.
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** New function `window-full-width-p' returns t if a window is as wide
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as its frame.
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@ -4364,35 +4364,6 @@ because it may lead to inefficient behavior for some change hook
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functions.
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@end defmac
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The two variables above are temporarily bound to @code{nil} during the
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time that any of these functions is running. This means that if one of
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these functions changes the buffer, that change won't run these
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functions. If you do want a hook function to make changes that run
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these functions, make it bind these variables back to their usual
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values.
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One inconvenient result of this protective feature is that you cannot
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have a function in @code{after-change-functions} or
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@code{before-change-functions} which changes the value of that variable.
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But that's not a real limitation. If you want those functions to change
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the list of functions to run, simply add one fixed function to the hook,
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and code that function to look in another variable for other functions
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to call. Here is an example:
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@example
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(setq my-own-after-change-functions nil)
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(defun indirect-after-change-function (beg end len)
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(let ((list my-own-after-change-functions))
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(while list
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(funcall (car list) beg end len)
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(setq list (cdr list)))))
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@group
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(add-hooks 'after-change-functions
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'indirect-after-change-function)
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@end group
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@end example
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@defvar first-change-hook
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This variable is a normal hook that is run whenever a buffer is changed
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that was previously in the unmodified state.
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@ -4404,6 +4375,13 @@ disabled; none of them run. This affects all the hook variables
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described above in this section, as well as the hooks attached to
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certain special text properties (@pxref{Special Properties}) and overlay
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properties (@pxref{Overlay Properties}).
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Also, this variable is bound to non-@code{nil} while running those
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same hook variables, so that by default modifying the buffer from
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a modification hook does not cause other modification hooks to be run.
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If you do want modification hooks to be run in a particular piece of
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code that is itself run from a modification hook, then rebind locally
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@code{inhibit-modification-hooks} to @code{nil}.
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@end defvar
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@ignore
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@ -1,3 +1,11 @@
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2007-08-21 Stefan Monnier <monnier@iro.umontreal.ca>
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* insdel.c (reset_var_on_error): New fun.
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(signal_before_change, signal_after_change):
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Use it to reset (after|before)-change-functions to nil in case of error.
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Bind inhibit-modification-hooks to t.
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Don't bind (after|before)-change-functions to nil while they run.
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2007-08-19 Andreas Schwab <schwab@suse.de>
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* alloc.c (pure): Round PURESIZE up.
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98
src/insdel.c
98
src/insdel.c
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@ -2137,6 +2137,21 @@ prepare_to_modify_buffer (start, end, preserve_ptr)
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#define FETCH_END \
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(! NILP (end_marker) ? Fmarker_position (end_marker) : end)
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/* Set a variable to nil if an error occurred.
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Don't change the variable if there was no error.
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VAL is a cons-cell (VARIABLE . NO-ERROR-FLAG).
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VARIABLE is the variable to maybe set to nil.
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NO-ERROR-FLAG is nil if there was an error,
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anything else meaning no error (so this function does nothing). */
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Lisp_Object
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reset_var_on_error (val)
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Lisp_Object val;
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{
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if (NILP (XCDR (val)))
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Fset (XCAR (val), Qnil);
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return Qnil;
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}
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/* Signal a change to the buffer immediately before it happens.
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START_INT and END_INT are the bounds of the text to be changed.
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@ -2152,6 +2167,7 @@ signal_before_change (start_int, end_int, preserve_ptr)
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Lisp_Object start_marker, end_marker;
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Lisp_Object preserve_marker;
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struct gcpro gcpro1, gcpro2, gcpro3;
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int count = SPECPDL_INDEX ();
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if (inhibit_modification_hooks)
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return;
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@ -2163,6 +2179,8 @@ signal_before_change (start_int, end_int, preserve_ptr)
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end_marker = Qnil;
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GCPRO3 (preserve_marker, start_marker, end_marker);
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specbind (Qinhibit_modification_hooks, Qt);
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/* If buffer is unmodified, run a special hook for that case. */
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if (SAVE_MODIFF >= MODIFF
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&& !NILP (Vfirst_change_hook)
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@ -2177,46 +2195,22 @@ signal_before_change (start_int, end_int, preserve_ptr)
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if (!NILP (Vbefore_change_functions))
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{
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Lisp_Object args[3];
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Lisp_Object before_change_functions;
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Lisp_Object after_change_functions;
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struct gcpro gcpro1, gcpro2;
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struct buffer *old = current_buffer;
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struct buffer *new;
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Lisp_Object rvoe_arg = Fcons (Qbefore_change_functions, Qnil);
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PRESERVE_VALUE;
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PRESERVE_START_END;
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/* "Bind" before-change-functions and after-change-functions
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to nil--but in a way that errors don't know about.
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That way, if there's an error in them, they will stay nil. */
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before_change_functions = Vbefore_change_functions;
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after_change_functions = Vafter_change_functions;
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Vbefore_change_functions = Qnil;
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Vafter_change_functions = Qnil;
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GCPRO2 (before_change_functions, after_change_functions);
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/* Mark before-change-functions to be reset to nil in case of error. */
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record_unwind_protect (reset_var_on_error, rvoe_arg);
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/* Actually run the hook functions. */
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args[0] = Qbefore_change_functions;
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args[1] = FETCH_START;
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args[2] = FETCH_END;
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run_hook_list_with_args (before_change_functions, 3, args);
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Frun_hook_with_args (3, args);
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/* "Unbind" the variables we "bound" to nil. Beware a
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buffer-local hook which changes the buffer when run (e.g. W3). */
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if (old != current_buffer)
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{
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new = current_buffer;
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set_buffer_internal (old);
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Vbefore_change_functions = before_change_functions;
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Vafter_change_functions = after_change_functions;
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set_buffer_internal (new);
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}
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else
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{
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Vbefore_change_functions = before_change_functions;
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Vafter_change_functions = after_change_functions;
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}
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UNGCPRO;
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/* There was no error: unarm the reset_on_error. */
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XSETCDR (rvoe_arg, Qt);
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}
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if (current_buffer->overlays_before || current_buffer->overlays_after)
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@ -2232,6 +2226,8 @@ signal_before_change (start_int, end_int, preserve_ptr)
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free_marker (end_marker);
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RESTORE_VALUE;
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UNGCPRO;
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unbind_to (count, Qnil);
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}
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/* Signal a change immediately after it happens.
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@ -2245,6 +2241,7 @@ void
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signal_after_change (charpos, lendel, lenins)
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int charpos, lendel, lenins;
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{
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int count = SPECPDL_INDEX ();
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if (inhibit_modification_hooks)
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return;
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@ -2275,48 +2272,25 @@ signal_after_change (charpos, lendel, lenins)
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if (!NILP (combine_after_change_list))
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Fcombine_after_change_execute ();
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specbind (Qinhibit_modification_hooks, Qt);
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if (!NILP (Vafter_change_functions))
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{
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Lisp_Object args[4];
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Lisp_Object before_change_functions;
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Lisp_Object after_change_functions;
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struct buffer *old = current_buffer;
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struct buffer *new;
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struct gcpro gcpro1, gcpro2;
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Lisp_Object rvoe_arg = Fcons (Qafter_change_functions, Qnil);
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/* "Bind" before-change-functions and after-change-functions
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to nil--but in a way that errors don't know about.
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That way, if there's an error in them, they will stay nil. */
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before_change_functions = Vbefore_change_functions;
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after_change_functions = Vafter_change_functions;
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Vbefore_change_functions = Qnil;
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Vafter_change_functions = Qnil;
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GCPRO2 (before_change_functions, after_change_functions);
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/* Mark after-change-functions to be reset to nil in case of error. */
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record_unwind_protect (reset_var_on_error, rvoe_arg);
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/* Actually run the hook functions. */
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args[0] = Qafter_change_functions;
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XSETFASTINT (args[1], charpos);
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XSETFASTINT (args[2], charpos + lenins);
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XSETFASTINT (args[3], lendel);
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run_hook_list_with_args (after_change_functions,
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4, args);
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Frun_hook_with_args (4, args);
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/* "Unbind" the variables we "bound" to nil. Beware a
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buffer-local hook which changes the buffer when run (e.g. W3). */
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if (old != current_buffer)
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{
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new = current_buffer;
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set_buffer_internal (old);
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Vbefore_change_functions = before_change_functions;
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Vafter_change_functions = after_change_functions;
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set_buffer_internal (new);
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}
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else
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{
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Vbefore_change_functions = before_change_functions;
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Vafter_change_functions = after_change_functions;
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}
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UNGCPRO;
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/* There was no error: unarm the reset_on_error. */
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XSETCDR (rvoe_arg, Qt);
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}
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if (current_buffer->overlays_before || current_buffer->overlays_after)
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@ -2332,6 +2306,8 @@ signal_after_change (charpos, lendel, lenins)
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if (lendel == 0)
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report_interval_modification (make_number (charpos),
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make_number (charpos + lenins));
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unbind_to (count, Qnil);
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}
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Lisp_Object
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