xref: /vim-8.2.3635/src/ex_eval.c (revision ea2d8d25)
1 /* vi:set ts=8 sts=4 sw=4 noet:
2  *
3  * VIM - Vi IMproved	by Bram Moolenaar
4  *
5  * Do ":help uganda"  in Vim to read copying and usage conditions.
6  * Do ":help credits" in Vim to see a list of people who contributed.
7  * See README.txt for an overview of the Vim source code.
8  */
9 
10 /*
11  * ex_eval.c: functions for Ex command line for the +eval feature.
12  */
13 
14 #include "vim.h"
15 
16 #if defined(FEAT_EVAL) || defined(PROTO)
17 
18 static char	*get_end_emsg(cstack_T *cstack);
19 
20 /*
21  * Exception handling terms:
22  *
23  *	:try		":try" command		\
24  *	    ...		try block		|
25  *	:catch RE	":catch" command	|
26  *	    ...		catch clause		|- try conditional
27  *	:finally	":finally" command	|
28  *	    ...		finally clause		|
29  *	:endtry		":endtry" command	/
30  *
31  * The try conditional may have any number of catch clauses and at most one
32  * finally clause.  A ":throw" command can be inside the try block, a catch
33  * clause, the finally clause, or in a function called or script sourced from
34  * there or even outside the try conditional.  Try conditionals may be nested.
35  */
36 
37 /*
38  * Configuration whether an exception is thrown on error or interrupt.  When
39  * the preprocessor macros below evaluate to FALSE, an error (did_emsg) or
40  * interrupt (got_int) under an active try conditional terminates the script
41  * after the non-active finally clauses of all active try conditionals have been
42  * executed.  Otherwise, errors and/or interrupts are converted into catchable
43  * exceptions (did_throw additionally set), which terminate the script only if
44  * not caught.  For user exceptions, only did_throw is set.  (Note: got_int can
45  * be set asynchronously afterwards by a SIGINT, so did_throw && got_int is not
46  * a reliant test that the exception currently being thrown is an interrupt
47  * exception.  Similarly, did_emsg can be set afterwards on an error in an
48  * (unskipped) conditional command inside an inactive conditional, so did_throw
49  * && did_emsg is not a reliant test that the exception currently being thrown
50  * is an error exception.)  -  The macros can be defined as expressions checking
51  * for a variable that is allowed to be changed during execution of a script.
52  */
53 #if 0
54 // Expressions used for testing during the development phase.
55 # define THROW_ON_ERROR		(!eval_to_number("$VIMNOERRTHROW"))
56 # define THROW_ON_INTERRUPT	(!eval_to_number("$VIMNOINTTHROW"))
57 # define THROW_TEST
58 #else
59 // Values used for the Vim release.
60 # define THROW_ON_ERROR		TRUE
61 # define THROW_ON_ERROR_TRUE
62 # define THROW_ON_INTERRUPT	TRUE
63 # define THROW_ON_INTERRUPT_TRUE
64 #endif
65 
66 /*
67  * When several errors appear in a row, setting "force_abort" is delayed until
68  * the failing command returned.  "cause_abort" is set to TRUE meanwhile, in
69  * order to indicate that situation.  This is useful when "force_abort" was set
70  * during execution of a function call from an expression: the aborting of the
71  * expression evaluation is done without producing any error messages, but all
72  * error messages on parsing errors during the expression evaluation are given
73  * (even if a try conditional is active).
74  */
75 static int cause_abort = FALSE;
76 
77 /*
78  * Return TRUE when immediately aborting on error, or when an interrupt
79  * occurred or an exception was thrown but not caught.  Use for ":{range}call"
80  * to check whether an aborted function that does not handle a range itself
81  * should be called again for the next line in the range.  Also used for
82  * cancelling expression evaluation after a function call caused an immediate
83  * abort.  Note that the first emsg() call temporarily resets "force_abort"
84  * until the throw point for error messages has been reached.  That is, during
85  * cancellation of an expression evaluation after an aborting function call or
86  * due to a parsing error, aborting() always returns the same value.
87  * "got_int" is also set by calling interrupt().
88  */
89     int
90 aborting(void)
91 {
92     return (did_emsg && force_abort) || got_int || did_throw;
93 }
94 
95 /*
96  * The value of "force_abort" is temporarily reset by the first emsg() call
97  * during an expression evaluation, and "cause_abort" is used instead.  It might
98  * be necessary to restore "force_abort" even before the throw point for the
99  * error message has been reached.  update_force_abort() should be called then.
100  */
101     void
102 update_force_abort(void)
103 {
104     if (cause_abort)
105 	force_abort = TRUE;
106 }
107 
108 /*
109  * Return TRUE if a command with a subcommand resulting in "retcode" should
110  * abort the script processing.  Can be used to suppress an autocommand after
111  * execution of a failing subcommand as long as the error message has not been
112  * displayed and actually caused the abortion.
113  */
114     int
115 should_abort(int retcode)
116 {
117     return ((retcode == FAIL && trylevel != 0 && !emsg_silent) || aborting());
118 }
119 
120 /*
121  * Return TRUE if a function with the "abort" flag should not be considered
122  * ended on an error.  This means that parsing commands is continued in order
123  * to find finally clauses to be executed, and that some errors in skipped
124  * commands are still reported.
125  */
126     int
127 aborted_in_try(void)
128 {
129     // This function is only called after an error.  In this case, "force_abort"
130     // determines whether searching for finally clauses is necessary.
131     return force_abort;
132 }
133 
134 /*
135  * cause_errthrow(): Cause a throw of an error exception if appropriate.
136  * Return TRUE if the error message should not be displayed by emsg().
137  * Sets "ignore", if the emsg() call should be ignored completely.
138  *
139  * When several messages appear in the same command, the first is usually the
140  * most specific one and used as the exception value.  The "severe" flag can be
141  * set to TRUE, if a later but severer message should be used instead.
142  */
143     int
144 cause_errthrow(
145     char_u	*mesg,
146     int		severe,
147     int		*ignore)
148 {
149     msglist_T	*elem;
150     msglist_T	**plist;
151 
152     /*
153      * Do nothing when displaying the interrupt message or reporting an
154      * uncaught exception (which has already been discarded then) at the top
155      * level.  Also when no exception can be thrown.  The message will be
156      * displayed by emsg().
157      */
158     if (suppress_errthrow)
159 	return FALSE;
160 
161     /*
162      * If emsg() has not been called previously, temporarily reset
163      * "force_abort" until the throw point for error messages has been
164      * reached.  This ensures that aborting() returns the same value for all
165      * errors that appear in the same command.  This means particularly that
166      * for parsing errors during expression evaluation emsg() will be called
167      * multiply, even when the expression is evaluated from a finally clause
168      * that was activated due to an aborting error, interrupt, or exception.
169      */
170     if (!did_emsg)
171     {
172 	cause_abort = force_abort;
173 	force_abort = FALSE;
174     }
175 
176     /*
177      * If no try conditional is active and no exception is being thrown and
178      * there has not been an error in a try conditional or a throw so far, do
179      * nothing (for compatibility of non-EH scripts).  The message will then
180      * be displayed by emsg().  When ":silent!" was used and we are not
181      * currently throwing an exception, do nothing.  The message text will
182      * then be stored to v:errmsg by emsg() without displaying it.
183      */
184     if (((trylevel == 0 && !cause_abort) || emsg_silent) && !did_throw)
185 	return FALSE;
186 
187     /*
188      * Ignore an interrupt message when inside a try conditional or when an
189      * exception is being thrown or when an error in a try conditional or
190      * throw has been detected previously.  This is important in order that an
191      * interrupt exception is catchable by the innermost try conditional and
192      * not replaced by an interrupt message error exception.
193      */
194     if (mesg == (char_u *)_(e_interr))
195     {
196 	*ignore = TRUE;
197 	return TRUE;
198     }
199 
200     /*
201      * Ensure that all commands in nested function calls and sourced files
202      * are aborted immediately.
203      */
204     cause_abort = TRUE;
205 
206     /*
207      * When an exception is being thrown, some commands (like conditionals) are
208      * not skipped.  Errors in those commands may affect what of the subsequent
209      * commands are regarded part of catch and finally clauses.  Catching the
210      * exception would then cause execution of commands not intended by the
211      * user, who wouldn't even get aware of the problem.  Therefor, discard the
212      * exception currently being thrown to prevent it from being caught.  Just
213      * execute finally clauses and terminate.
214      */
215     if (did_throw)
216     {
217 	// When discarding an interrupt exception, reset got_int to prevent the
218 	// same interrupt being converted to an exception again and discarding
219 	// the error exception we are about to throw here.
220 	if (current_exception->type == ET_INTERRUPT)
221 	    got_int = FALSE;
222 	discard_current_exception();
223     }
224 
225 #ifdef THROW_TEST
226     if (!THROW_ON_ERROR)
227     {
228 	/*
229 	 * Print error message immediately without searching for a matching
230 	 * catch clause; just finally clauses are executed before the script
231 	 * is terminated.
232 	 */
233 	return FALSE;
234     }
235     else
236 #endif
237     {
238 	/*
239 	 * Prepare the throw of an error exception, so that everything will
240 	 * be aborted (except for executing finally clauses), until the error
241 	 * exception is caught; if still uncaught at the top level, the error
242 	 * message will be displayed and the script processing terminated
243 	 * then.  -  This function has no access to the conditional stack.
244 	 * Thus, the actual throw is made after the failing command has
245 	 * returned.  -  Throw only the first of several errors in a row, except
246 	 * a severe error is following.
247 	 */
248 	if (msg_list != NULL)
249 	{
250 	    plist = msg_list;
251 	    while (*plist != NULL)
252 		plist = &(*plist)->next;
253 
254 	    elem = ALLOC_CLEAR_ONE(msglist_T);
255 	    if (elem == NULL)
256 	    {
257 		suppress_errthrow = TRUE;
258 		emsg(_(e_outofmem));
259 	    }
260 	    else
261 	    {
262 		elem->msg = (char *)vim_strsave(mesg);
263 		if (elem->msg == NULL)
264 		{
265 		    vim_free(elem);
266 		    suppress_errthrow = TRUE;
267 		    emsg(_(e_outofmem));
268 		}
269 		else
270 		{
271 		    elem->next = NULL;
272 		    elem->throw_msg = NULL;
273 		    *plist = elem;
274 		    if (plist == msg_list || severe)
275 		    {
276 			char	    *tmsg;
277 
278 			// Skip the extra "Vim " prefix for message "E458".
279 			tmsg = elem->msg;
280 			if (STRNCMP(tmsg, "Vim E", 5) == 0
281 				&& VIM_ISDIGIT(tmsg[5])
282 				&& VIM_ISDIGIT(tmsg[6])
283 				&& VIM_ISDIGIT(tmsg[7])
284 				&& tmsg[8] == ':'
285 				&& tmsg[9] == ' ')
286 			    (*msg_list)->throw_msg = &tmsg[4];
287 			else
288 			    (*msg_list)->throw_msg = tmsg;
289 		    }
290 
291 		    // Get the source name and lnum now, it may change before
292 		    // reaching do_errthrow().
293 		    elem->sfile = estack_sfile(FALSE);
294 		    elem->slnum = SOURCING_LNUM;
295 		}
296 	    }
297 	}
298 	return TRUE;
299     }
300 }
301 
302 /*
303  * Free a "msg_list" and the messages it contains.
304  */
305     static void
306 free_msglist(msglist_T *l)
307 {
308     msglist_T  *messages, *next;
309 
310     messages = l;
311     while (messages != NULL)
312     {
313 	next = messages->next;
314 	vim_free(messages->msg);
315 	vim_free(messages->sfile);
316 	vim_free(messages);
317 	messages = next;
318     }
319 }
320 
321 /*
322  * Free global "*msg_list" and the messages it contains, then set "*msg_list"
323  * to NULL.
324  */
325     void
326 free_global_msglist(void)
327 {
328     free_msglist(*msg_list);
329     *msg_list = NULL;
330 }
331 
332 /*
333  * Throw the message specified in the call to cause_errthrow() above as an
334  * error exception.  If cstack is NULL, postpone the throw until do_cmdline()
335  * has returned (see do_one_cmd()).
336  */
337     void
338 do_errthrow(cstack_T *cstack, char_u *cmdname)
339 {
340     /*
341      * Ensure that all commands in nested function calls and sourced files
342      * are aborted immediately.
343      */
344     if (cause_abort)
345     {
346 	cause_abort = FALSE;
347 	force_abort = TRUE;
348     }
349 
350     // If no exception is to be thrown or the conversion should be done after
351     // returning to a previous invocation of do_one_cmd(), do nothing.
352     if (msg_list == NULL || *msg_list == NULL)
353 	return;
354 
355     if (throw_exception(*msg_list, ET_ERROR, cmdname) == FAIL)
356 	free_msglist(*msg_list);
357     else
358     {
359 	if (cstack != NULL)
360 	    do_throw(cstack);
361 	else
362 	    need_rethrow = TRUE;
363     }
364     *msg_list = NULL;
365 }
366 
367 /*
368  * do_intthrow(): Replace the current exception by an interrupt or interrupt
369  * exception if appropriate.  Return TRUE if the current exception is discarded,
370  * FALSE otherwise.
371  */
372     int
373 do_intthrow(cstack_T *cstack)
374 {
375     /*
376      * If no interrupt occurred or no try conditional is active and no exception
377      * is being thrown, do nothing (for compatibility of non-EH scripts).
378      */
379     if (!got_int || (trylevel == 0 && !did_throw))
380 	return FALSE;
381 
382 #ifdef THROW_TEST	// avoid warning for condition always true
383     if (!THROW_ON_INTERRUPT)
384     {
385 	/*
386 	 * The interrupt aborts everything except for executing finally clauses.
387 	 * Discard any user or error or interrupt exception currently being
388 	 * thrown.
389 	 */
390 	if (did_throw)
391 	    discard_current_exception();
392     }
393     else
394 #endif
395     {
396 	/*
397 	 * Throw an interrupt exception, so that everything will be aborted
398 	 * (except for executing finally clauses), until the interrupt exception
399 	 * is caught; if still uncaught at the top level, the script processing
400 	 * will be terminated then.  -  If an interrupt exception is already
401 	 * being thrown, do nothing.
402 	 *
403 	 */
404 	if (did_throw)
405 	{
406 	    if (current_exception->type == ET_INTERRUPT)
407 		return FALSE;
408 
409 	    // An interrupt exception replaces any user or error exception.
410 	    discard_current_exception();
411 	}
412 	if (throw_exception("Vim:Interrupt", ET_INTERRUPT, NULL) != FAIL)
413 	    do_throw(cstack);
414     }
415 
416     return TRUE;
417 }
418 
419 /*
420  * Get an exception message that is to be stored in current_exception->value.
421  */
422     char *
423 get_exception_string(
424     void	*value,
425     except_type_T type,
426     char_u	*cmdname,
427     int		*should_free)
428 {
429     char	*ret;
430     char	*mesg;
431     int		cmdlen;
432     char	*p, *val;
433 
434     if (type == ET_ERROR)
435     {
436 	*should_free = TRUE;
437 	mesg = ((msglist_T *)value)->throw_msg;
438 	if (cmdname != NULL && *cmdname != NUL)
439 	{
440 	    cmdlen = (int)STRLEN(cmdname);
441 	    ret = (char *)vim_strnsave((char_u *)"Vim(",
442 						4 + cmdlen + 2 + STRLEN(mesg));
443 	    if (ret == NULL)
444 		return ret;
445 	    STRCPY(&ret[4], cmdname);
446 	    STRCPY(&ret[4 + cmdlen], "):");
447 	    val = ret + 4 + cmdlen + 2;
448 	}
449 	else
450 	{
451 	    ret = (char *)vim_strnsave((char_u *)"Vim:", 4 + STRLEN(mesg));
452 	    if (ret == NULL)
453 		return ret;
454 	    val = ret + 4;
455 	}
456 
457 	// msg_add_fname may have been used to prefix the message with a file
458 	// name in quotes.  In the exception value, put the file name in
459 	// parentheses and move it to the end.
460 	for (p = mesg; ; p++)
461 	{
462 	    if (*p == NUL
463 		    || (*p == 'E'
464 			&& VIM_ISDIGIT(p[1])
465 			&& (p[2] == ':'
466 			    || (VIM_ISDIGIT(p[2])
467 				&& (p[3] == ':'
468 				    || (VIM_ISDIGIT(p[3])
469 					&& p[4] == ':'))))))
470 	    {
471 		if (*p == NUL || p == mesg)
472 		    STRCAT(val, mesg);  // 'E123' missing or at beginning
473 		else
474 		{
475 		    // '"filename" E123: message text'
476 		    if (mesg[0] != '"' || p-2 < &mesg[1] ||
477 			    p[-2] != '"' || p[-1] != ' ')
478 			// "E123:" is part of the file name.
479 			continue;
480 
481 		    STRCAT(val, p);
482 		    p[-2] = NUL;
483 		    sprintf((char *)(val + STRLEN(p)), " (%s)", &mesg[1]);
484 		    p[-2] = '"';
485 		}
486 		break;
487 	    }
488 	}
489     }
490     else
491     {
492 	*should_free = FALSE;
493 	ret = value;
494     }
495 
496     return ret;
497 }
498 
499 
500 /*
501  * Throw a new exception.  Return FAIL when out of memory or it was tried to
502  * throw an illegal user exception.  "value" is the exception string for a
503  * user or interrupt exception, or points to a message list in case of an
504  * error exception.
505  */
506     int
507 throw_exception(void *value, except_type_T type, char_u *cmdname)
508 {
509     except_T	*excp;
510     int		should_free;
511 
512     /*
513      * Disallow faking Interrupt or error exceptions as user exceptions.  They
514      * would be treated differently from real interrupt or error exceptions
515      * when no active try block is found, see do_cmdline().
516      */
517     if (type == ET_USER)
518     {
519 	if (STRNCMP((char_u *)value, "Vim", 3) == 0
520 		&& (((char_u *)value)[3] == NUL || ((char_u *)value)[3] == ':'
521 		    || ((char_u *)value)[3] == '('))
522 	{
523 	    emsg(_("E608: Cannot :throw exceptions with 'Vim' prefix"));
524 	    goto fail;
525 	}
526     }
527 
528     excp = ALLOC_ONE(except_T);
529     if (excp == NULL)
530 	goto nomem;
531 
532     if (type == ET_ERROR)
533 	// Store the original message and prefix the exception value with
534 	// "Vim:" or, if a command name is given, "Vim(cmdname):".
535 	excp->messages = (msglist_T *)value;
536 
537     excp->value = get_exception_string(value, type, cmdname, &should_free);
538     if (excp->value == NULL && should_free)
539 	goto nomem;
540 
541     excp->type = type;
542     if (type == ET_ERROR && ((msglist_T *)value)->sfile != NULL)
543     {
544 	msglist_T *entry = (msglist_T *)value;
545 
546 	excp->throw_name = entry->sfile;
547 	entry->sfile = NULL;
548 	excp->throw_lnum = entry->slnum;
549     }
550     else
551     {
552 	excp->throw_name = estack_sfile(FALSE);
553 	if (excp->throw_name == NULL)
554 	    excp->throw_name = vim_strsave((char_u *)"");
555 	if (excp->throw_name == NULL)
556 	{
557 	    if (should_free)
558 		vim_free(excp->value);
559 	    goto nomem;
560 	}
561 	excp->throw_lnum = SOURCING_LNUM;
562     }
563 
564     if (p_verbose >= 13 || debug_break_level > 0)
565     {
566 	int	save_msg_silent = msg_silent;
567 
568 	if (debug_break_level > 0)
569 	    msg_silent = FALSE;		// display messages
570 	else
571 	    verbose_enter();
572 	++no_wait_return;
573 	if (debug_break_level > 0 || *p_vfile == NUL)
574 	    msg_scroll = TRUE;	    // always scroll up, don't overwrite
575 
576 	smsg(_("Exception thrown: %s"), excp->value);
577 	msg_puts("\n");   // don't overwrite this either
578 
579 	if (debug_break_level > 0 || *p_vfile == NUL)
580 	    cmdline_row = msg_row;
581 	--no_wait_return;
582 	if (debug_break_level > 0)
583 	    msg_silent = save_msg_silent;
584 	else
585 	    verbose_leave();
586     }
587 
588     current_exception = excp;
589     return OK;
590 
591 nomem:
592     vim_free(excp);
593     suppress_errthrow = TRUE;
594     emsg(_(e_outofmem));
595 fail:
596     current_exception = NULL;
597     return FAIL;
598 }
599 
600 /*
601  * Discard an exception.  "was_finished" is set when the exception has been
602  * caught and the catch clause has been ended normally.
603  */
604     static void
605 discard_exception(except_T *excp, int was_finished)
606 {
607     char_u		*saved_IObuff;
608 
609     if (excp == NULL)
610     {
611 	internal_error("discard_exception()");
612 	return;
613     }
614 
615     if (p_verbose >= 13 || debug_break_level > 0)
616     {
617 	int	save_msg_silent = msg_silent;
618 
619 	saved_IObuff = vim_strsave(IObuff);
620 	if (debug_break_level > 0)
621 	    msg_silent = FALSE;		// display messages
622 	else
623 	    verbose_enter();
624 	++no_wait_return;
625 	if (debug_break_level > 0 || *p_vfile == NUL)
626 	    msg_scroll = TRUE;	    // always scroll up, don't overwrite
627 	smsg(was_finished
628 		    ? _("Exception finished: %s")
629 		    : _("Exception discarded: %s"),
630 		excp->value);
631 	msg_puts("\n");   // don't overwrite this either
632 	if (debug_break_level > 0 || *p_vfile == NUL)
633 	    cmdline_row = msg_row;
634 	--no_wait_return;
635 	if (debug_break_level > 0)
636 	    msg_silent = save_msg_silent;
637 	else
638 	    verbose_leave();
639 	STRCPY(IObuff, saved_IObuff);
640 	vim_free(saved_IObuff);
641     }
642     if (excp->type != ET_INTERRUPT)
643 	vim_free(excp->value);
644     if (excp->type == ET_ERROR)
645 	free_msglist(excp->messages);
646     vim_free(excp->throw_name);
647     vim_free(excp);
648 }
649 
650 /*
651  * Discard the exception currently being thrown.
652  */
653     void
654 discard_current_exception(void)
655 {
656     if (current_exception != NULL)
657     {
658 	discard_exception(current_exception, FALSE);
659 	current_exception = NULL;
660     }
661     did_throw = FALSE;
662     need_rethrow = FALSE;
663 }
664 
665 /*
666  * Put an exception on the caught stack.
667  */
668     void
669 catch_exception(except_T *excp)
670 {
671     excp->caught = caught_stack;
672     caught_stack = excp;
673     set_vim_var_string(VV_EXCEPTION, (char_u *)excp->value, -1);
674     if (*excp->throw_name != NUL)
675     {
676 	if (excp->throw_lnum != 0)
677 	    vim_snprintf((char *)IObuff, IOSIZE, _("%s, line %ld"),
678 				    excp->throw_name, (long)excp->throw_lnum);
679 	else
680 	    vim_snprintf((char *)IObuff, IOSIZE, "%s", excp->throw_name);
681 	set_vim_var_string(VV_THROWPOINT, IObuff, -1);
682     }
683     else
684 	// throw_name not set on an exception from a command that was typed.
685 	set_vim_var_string(VV_THROWPOINT, NULL, -1);
686 
687     if (p_verbose >= 13 || debug_break_level > 0)
688     {
689 	int	save_msg_silent = msg_silent;
690 
691 	if (debug_break_level > 0)
692 	    msg_silent = FALSE;		// display messages
693 	else
694 	    verbose_enter();
695 	++no_wait_return;
696 	if (debug_break_level > 0 || *p_vfile == NUL)
697 	    msg_scroll = TRUE;	    // always scroll up, don't overwrite
698 
699 	smsg(_("Exception caught: %s"), excp->value);
700 	msg_puts("\n");   // don't overwrite this either
701 
702 	if (debug_break_level > 0 || *p_vfile == NUL)
703 	    cmdline_row = msg_row;
704 	--no_wait_return;
705 	if (debug_break_level > 0)
706 	    msg_silent = save_msg_silent;
707 	else
708 	    verbose_leave();
709     }
710 }
711 
712 /*
713  * Remove an exception from the caught stack.
714  */
715     static void
716 finish_exception(except_T *excp)
717 {
718     if (excp != caught_stack)
719 	internal_error("finish_exception()");
720     caught_stack = caught_stack->caught;
721     if (caught_stack != NULL)
722     {
723 	set_vim_var_string(VV_EXCEPTION, (char_u *)caught_stack->value, -1);
724 	if (*caught_stack->throw_name != NUL)
725 	{
726 	    if (caught_stack->throw_lnum != 0)
727 		vim_snprintf((char *)IObuff, IOSIZE,
728 			_("%s, line %ld"), caught_stack->throw_name,
729 			(long)caught_stack->throw_lnum);
730 	    else
731 		vim_snprintf((char *)IObuff, IOSIZE, "%s",
732 						    caught_stack->throw_name);
733 	    set_vim_var_string(VV_THROWPOINT, IObuff, -1);
734 	}
735 	else
736 	    // throw_name not set on an exception from a command that was
737 	    // typed.
738 	    set_vim_var_string(VV_THROWPOINT, NULL, -1);
739     }
740     else
741     {
742 	set_vim_var_string(VV_EXCEPTION, NULL, -1);
743 	set_vim_var_string(VV_THROWPOINT, NULL, -1);
744     }
745 
746     // Discard the exception, but use the finish message for 'verbose'.
747     discard_exception(excp, TRUE);
748 }
749 
750 /*
751  * Flags specifying the message displayed by report_pending.
752  */
753 #define RP_MAKE		0
754 #define RP_RESUME	1
755 #define RP_DISCARD	2
756 
757 /*
758  * Report information about something pending in a finally clause if required by
759  * the 'verbose' option or when debugging.  "action" tells whether something is
760  * made pending or something pending is resumed or discarded.  "pending" tells
761  * what is pending.  "value" specifies the return value for a pending ":return"
762  * or the exception value for a pending exception.
763  */
764     static void
765 report_pending(int action, int pending, void *value)
766 {
767     char	*mesg;
768     char	*s;
769     int		save_msg_silent;
770 
771 
772     switch (action)
773     {
774 	case RP_MAKE:
775 	    mesg = _("%s made pending");
776 	    break;
777 	case RP_RESUME:
778 	    mesg = _("%s resumed");
779 	    break;
780 	// case RP_DISCARD:
781 	default:
782 	    mesg = _("%s discarded");
783 	    break;
784     }
785 
786     switch (pending)
787     {
788 	case CSTP_NONE:
789 	    return;
790 
791 	case CSTP_CONTINUE:
792 	    s = ":continue";
793 	    break;
794 	case CSTP_BREAK:
795 	    s = ":break";
796 	    break;
797 	case CSTP_FINISH:
798 	    s = ":finish";
799 	    break;
800 	case CSTP_RETURN:
801 	    // ":return" command producing value, allocated
802 	    s = (char *)get_return_cmd(value);
803 	    break;
804 
805 	default:
806 	    if (pending & CSTP_THROW)
807 	    {
808 		vim_snprintf((char *)IObuff, IOSIZE, mesg, _("Exception"));
809 		mesg = (char *)vim_strnsave(IObuff, STRLEN(IObuff) + 4);
810 		STRCAT(mesg, ": %s");
811 		s = (char *)((except_T *)value)->value;
812 	    }
813 	    else if ((pending & CSTP_ERROR) && (pending & CSTP_INTERRUPT))
814 		s = _("Error and interrupt");
815 	    else if (pending & CSTP_ERROR)
816 		s = _("Error");
817 	    else // if (pending & CSTP_INTERRUPT)
818 		s = _("Interrupt");
819     }
820 
821     save_msg_silent = msg_silent;
822     if (debug_break_level > 0)
823 	msg_silent = FALSE;	// display messages
824     ++no_wait_return;
825     msg_scroll = TRUE;		// always scroll up, don't overwrite
826     smsg(mesg, s);
827     msg_puts("\n");   // don't overwrite this either
828     cmdline_row = msg_row;
829     --no_wait_return;
830     if (debug_break_level > 0)
831 	msg_silent = save_msg_silent;
832 
833     if (pending == CSTP_RETURN)
834 	vim_free(s);
835     else if (pending & CSTP_THROW)
836 	vim_free(mesg);
837 }
838 
839 /*
840  * If something is made pending in a finally clause, report it if required by
841  * the 'verbose' option or when debugging.
842  */
843     void
844 report_make_pending(int pending, void *value)
845 {
846     if (p_verbose >= 14 || debug_break_level > 0)
847     {
848 	if (debug_break_level <= 0)
849 	    verbose_enter();
850 	report_pending(RP_MAKE, pending, value);
851 	if (debug_break_level <= 0)
852 	    verbose_leave();
853     }
854 }
855 
856 /*
857  * If something pending in a finally clause is resumed at the ":endtry", report
858  * it if required by the 'verbose' option or when debugging.
859  */
860     static void
861 report_resume_pending(int pending, void *value)
862 {
863     if (p_verbose >= 14 || debug_break_level > 0)
864     {
865 	if (debug_break_level <= 0)
866 	    verbose_enter();
867 	report_pending(RP_RESUME, pending, value);
868 	if (debug_break_level <= 0)
869 	    verbose_leave();
870     }
871 }
872 
873 /*
874  * If something pending in a finally clause is discarded, report it if required
875  * by the 'verbose' option or when debugging.
876  */
877     static void
878 report_discard_pending(int pending, void *value)
879 {
880     if (p_verbose >= 14 || debug_break_level > 0)
881     {
882 	if (debug_break_level <= 0)
883 	    verbose_enter();
884 	report_pending(RP_DISCARD, pending, value);
885 	if (debug_break_level <= 0)
886 	    verbose_leave();
887     }
888 }
889 
890 
891 /*
892  * ":eval".
893  */
894     void
895 ex_eval(exarg_T *eap)
896 {
897     typval_T	tv;
898     evalarg_T	evalarg;
899 
900     fill_evalarg_from_eap(&evalarg, eap, eap->skip);
901 
902     if (eval0(eap->arg, &tv, eap, &evalarg) == OK)
903 	clear_tv(&tv);
904 
905     clear_evalarg(&evalarg, eap);
906 }
907 
908 /*
909  * ":if".
910  */
911     void
912 ex_if(exarg_T *eap)
913 {
914     int		error;
915     int		skip;
916     int		result;
917     cstack_T	*cstack = eap->cstack;
918 
919     if (cstack->cs_idx == CSTACK_LEN - 1)
920 	eap->errmsg = _("E579: :if nesting too deep");
921     else
922     {
923 	++cstack->cs_idx;
924 	cstack->cs_flags[cstack->cs_idx] = 0;
925 
926 	/*
927 	 * Don't do something after an error, interrupt, or throw, or when there
928 	 * is a surrounding conditional and it was not active.
929 	 */
930 	skip = did_emsg || got_int || did_throw || (cstack->cs_idx > 0
931 		&& !(cstack->cs_flags[cstack->cs_idx - 1] & CSF_ACTIVE));
932 
933 	result = eval_to_bool(eap->arg, &error, eap, skip);
934 
935 	if (!skip && !error)
936 	{
937 	    if (result)
938 		cstack->cs_flags[cstack->cs_idx] = CSF_ACTIVE | CSF_TRUE;
939 	}
940 	else
941 	    // set TRUE, so this conditional will never get active
942 	    cstack->cs_flags[cstack->cs_idx] = CSF_TRUE;
943     }
944 }
945 
946 /*
947  * ":endif".
948  */
949     void
950 ex_endif(exarg_T *eap)
951 {
952     did_endif = TRUE;
953     if (eap->cstack->cs_idx < 0
954 	    || (eap->cstack->cs_flags[eap->cstack->cs_idx]
955 					   & (CSF_WHILE | CSF_FOR | CSF_TRY)))
956 	eap->errmsg = _(e_endif_without_if);
957     else
958     {
959 	/*
960 	 * When debugging or a breakpoint was encountered, display the debug
961 	 * prompt (if not already done).  This shows the user that an ":endif"
962 	 * is executed when the ":if" or a previous ":elseif" was not TRUE.
963 	 * Handle a ">quit" debug command as if an interrupt had occurred before
964 	 * the ":endif".  That is, throw an interrupt exception if appropriate.
965 	 * Doing this here prevents an exception for a parsing error being
966 	 * discarded by throwing the interrupt exception later on.
967 	 */
968 	if (!(eap->cstack->cs_flags[eap->cstack->cs_idx] & CSF_TRUE)
969 						    && dbg_check_skipped(eap))
970 	    (void)do_intthrow(eap->cstack);
971 
972 	--eap->cstack->cs_idx;
973     }
974 }
975 
976 /*
977  * ":else" and ":elseif".
978  */
979     void
980 ex_else(exarg_T *eap)
981 {
982     int		error;
983     int		skip;
984     int		result;
985     cstack_T	*cstack = eap->cstack;
986 
987     /*
988      * Don't do something after an error, interrupt, or throw, or when there is
989      * a surrounding conditional and it was not active.
990      */
991     skip = did_emsg || got_int || did_throw || (cstack->cs_idx > 0
992 	    && !(cstack->cs_flags[cstack->cs_idx - 1] & CSF_ACTIVE));
993 
994     if (cstack->cs_idx < 0
995 	    || (cstack->cs_flags[cstack->cs_idx]
996 					   & (CSF_WHILE | CSF_FOR | CSF_TRY)))
997     {
998 	if (eap->cmdidx == CMD_else)
999 	{
1000 	    eap->errmsg = _(e_else_without_if);
1001 	    return;
1002 	}
1003 	eap->errmsg = _(e_elseif_without_if);
1004 	skip = TRUE;
1005     }
1006     else if (cstack->cs_flags[cstack->cs_idx] & CSF_ELSE)
1007     {
1008 	if (eap->cmdidx == CMD_else)
1009 	{
1010 	    eap->errmsg = _("E583: multiple :else");
1011 	    return;
1012 	}
1013 	eap->errmsg = _("E584: :elseif after :else");
1014 	skip = TRUE;
1015     }
1016 
1017     // if skipping or the ":if" was TRUE, reset ACTIVE, otherwise set it
1018     if (skip || cstack->cs_flags[cstack->cs_idx] & CSF_TRUE)
1019     {
1020 	if (eap->errmsg == NULL)
1021 	    cstack->cs_flags[cstack->cs_idx] = CSF_TRUE;
1022 	skip = TRUE;	// don't evaluate an ":elseif"
1023     }
1024     else
1025 	cstack->cs_flags[cstack->cs_idx] = CSF_ACTIVE;
1026 
1027     /*
1028      * When debugging or a breakpoint was encountered, display the debug prompt
1029      * (if not already done).  This shows the user that an ":else" or ":elseif"
1030      * is executed when the ":if" or previous ":elseif" was not TRUE.  Handle
1031      * a ">quit" debug command as if an interrupt had occurred before the
1032      * ":else" or ":elseif".  That is, set "skip" and throw an interrupt
1033      * exception if appropriate.  Doing this here prevents that an exception
1034      * for a parsing errors is discarded when throwing the interrupt exception
1035      * later on.
1036      */
1037     if (!skip && dbg_check_skipped(eap) && got_int)
1038     {
1039 	(void)do_intthrow(cstack);
1040 	skip = TRUE;
1041     }
1042 
1043     if (eap->cmdidx == CMD_elseif)
1044     {
1045 	result = eval_to_bool(eap->arg, &error, eap, skip);
1046 
1047 	// When throwing error exceptions, we want to throw always the first
1048 	// of several errors in a row.  This is what actually happens when
1049 	// a conditional error was detected above and there is another failure
1050 	// when parsing the expression.  Since the skip flag is set in this
1051 	// case, the parsing error will be ignored by emsg().
1052 	if (!skip && !error)
1053 	{
1054 	    if (result)
1055 		cstack->cs_flags[cstack->cs_idx] = CSF_ACTIVE | CSF_TRUE;
1056 	    else
1057 		cstack->cs_flags[cstack->cs_idx] = 0;
1058 	}
1059 	else if (eap->errmsg == NULL)
1060 	    // set TRUE, so this conditional will never get active
1061 	    cstack->cs_flags[cstack->cs_idx] = CSF_TRUE;
1062     }
1063     else
1064 	cstack->cs_flags[cstack->cs_idx] |= CSF_ELSE;
1065 }
1066 
1067 /*
1068  * Handle ":while" and ":for".
1069  */
1070     void
1071 ex_while(exarg_T *eap)
1072 {
1073     int		error;
1074     int		skip;
1075     int		result;
1076     cstack_T	*cstack = eap->cstack;
1077 
1078     if (cstack->cs_idx == CSTACK_LEN - 1)
1079 	eap->errmsg = _("E585: :while/:for nesting too deep");
1080     else
1081     {
1082 	/*
1083 	 * The loop flag is set when we have jumped back from the matching
1084 	 * ":endwhile" or ":endfor".  When not set, need to initialise this
1085 	 * cstack entry.
1086 	 */
1087 	if ((cstack->cs_lflags & CSL_HAD_LOOP) == 0)
1088 	{
1089 	    ++cstack->cs_idx;
1090 	    ++cstack->cs_looplevel;
1091 	    cstack->cs_line[cstack->cs_idx] = -1;
1092 	}
1093 	cstack->cs_flags[cstack->cs_idx] =
1094 			       eap->cmdidx == CMD_while ? CSF_WHILE : CSF_FOR;
1095 
1096 	/*
1097 	 * Don't do something after an error, interrupt, or throw, or when
1098 	 * there is a surrounding conditional and it was not active.
1099 	 */
1100 	skip = did_emsg || got_int || did_throw || (cstack->cs_idx > 0
1101 		&& !(cstack->cs_flags[cstack->cs_idx - 1] & CSF_ACTIVE));
1102 	if (eap->cmdidx == CMD_while)
1103 	{
1104 	    /*
1105 	     * ":while bool-expr"
1106 	     */
1107 	    result = eval_to_bool(eap->arg, &error, eap, skip);
1108 	}
1109 	else
1110 	{
1111 	    void	*fi;
1112 	    evalarg_T	evalarg;
1113 
1114 	    CLEAR_FIELD(evalarg);
1115 	    evalarg.eval_flags = skip ? 0 : EVAL_EVALUATE;
1116 	    if (getline_equal(eap->getline, eap->cookie, getsourceline))
1117 	    {
1118 		evalarg.eval_getline = eap->getline;
1119 		evalarg.eval_cookie = eap->cookie;
1120 	    }
1121 
1122 	    /*
1123 	     * ":for var in list-expr"
1124 	     */
1125 	    if ((cstack->cs_lflags & CSL_HAD_LOOP) != 0)
1126 	    {
1127 		// Jumping here from a ":continue" or ":endfor": use the
1128 		// previously evaluated list.
1129 		fi = cstack->cs_forinfo[cstack->cs_idx];
1130 		error = FALSE;
1131 
1132 		// the "in expr" is not used, skip over it
1133 		skip_for_lines(fi, &evalarg);
1134 	    }
1135 	    else
1136 	    {
1137 		// Evaluate the argument and get the info in a structure.
1138 		fi = eval_for_line(eap->arg, &error, eap, &evalarg);
1139 		cstack->cs_forinfo[cstack->cs_idx] = fi;
1140 	    }
1141 
1142 	    // use the element at the start of the list and advance
1143 	    if (!error && fi != NULL && !skip)
1144 		result = next_for_item(fi, eap->arg);
1145 	    else
1146 		result = FALSE;
1147 
1148 	    if (!result)
1149 	    {
1150 		free_for_info(fi);
1151 		cstack->cs_forinfo[cstack->cs_idx] = NULL;
1152 	    }
1153 	    clear_evalarg(&evalarg, eap);
1154 	}
1155 
1156 	/*
1157 	 * If this cstack entry was just initialised and is active, set the
1158 	 * loop flag, so do_cmdline() will set the line number in cs_line[].
1159 	 * If executing the command a second time, clear the loop flag.
1160 	 */
1161 	if (!skip && !error && result)
1162 	{
1163 	    cstack->cs_flags[cstack->cs_idx] |= (CSF_ACTIVE | CSF_TRUE);
1164 	    cstack->cs_lflags ^= CSL_HAD_LOOP;
1165 	}
1166 	else
1167 	{
1168 	    cstack->cs_lflags &= ~CSL_HAD_LOOP;
1169 	    // If the ":while" evaluates to FALSE or ":for" is past the end of
1170 	    // the list, show the debug prompt at the ":endwhile"/":endfor" as
1171 	    // if there was a ":break" in a ":while"/":for" evaluating to
1172 	    // TRUE.
1173 	    if (!skip && !error)
1174 		cstack->cs_flags[cstack->cs_idx] |= CSF_TRUE;
1175 	}
1176     }
1177 }
1178 
1179 /*
1180  * ":continue"
1181  */
1182     void
1183 ex_continue(exarg_T *eap)
1184 {
1185     int		idx;
1186     cstack_T	*cstack = eap->cstack;
1187 
1188     if (cstack->cs_looplevel <= 0 || cstack->cs_idx < 0)
1189 	eap->errmsg = _(e_continue);
1190     else
1191     {
1192 	// Try to find the matching ":while".  This might stop at a try
1193 	// conditional not in its finally clause (which is then to be executed
1194 	// next).  Therefor, inactivate all conditionals except the ":while"
1195 	// itself (if reached).
1196 	idx = cleanup_conditionals(cstack, CSF_WHILE | CSF_FOR, FALSE);
1197 	if (idx >= 0 && (cstack->cs_flags[idx] & (CSF_WHILE | CSF_FOR)))
1198 	{
1199 	    rewind_conditionals(cstack, idx, CSF_TRY, &cstack->cs_trylevel);
1200 
1201 	    /*
1202 	     * Set CSL_HAD_CONT, so do_cmdline() will jump back to the
1203 	     * matching ":while".
1204 	     */
1205 	    cstack->cs_lflags |= CSL_HAD_CONT;	// let do_cmdline() handle it
1206 	}
1207 	else
1208 	{
1209 	    // If a try conditional not in its finally clause is reached first,
1210 	    // make the ":continue" pending for execution at the ":endtry".
1211 	    cstack->cs_pending[idx] = CSTP_CONTINUE;
1212 	    report_make_pending(CSTP_CONTINUE, NULL);
1213 	}
1214     }
1215 }
1216 
1217 /*
1218  * ":break"
1219  */
1220     void
1221 ex_break(exarg_T *eap)
1222 {
1223     int		idx;
1224     cstack_T	*cstack = eap->cstack;
1225 
1226     if (cstack->cs_looplevel <= 0 || cstack->cs_idx < 0)
1227 	eap->errmsg = _(e_break);
1228     else
1229     {
1230 	// Inactivate conditionals until the matching ":while" or a try
1231 	// conditional not in its finally clause (which is then to be
1232 	// executed next) is found.  In the latter case, make the ":break"
1233 	// pending for execution at the ":endtry".
1234 	idx = cleanup_conditionals(cstack, CSF_WHILE | CSF_FOR, TRUE);
1235 	if (idx >= 0 && !(cstack->cs_flags[idx] & (CSF_WHILE | CSF_FOR)))
1236 	{
1237 	    cstack->cs_pending[idx] = CSTP_BREAK;
1238 	    report_make_pending(CSTP_BREAK, NULL);
1239 	}
1240     }
1241 }
1242 
1243 /*
1244  * ":endwhile" and ":endfor"
1245  */
1246     void
1247 ex_endwhile(exarg_T *eap)
1248 {
1249     cstack_T	*cstack = eap->cstack;
1250     int		idx;
1251     char	*err;
1252     int		csf;
1253     int		fl;
1254 
1255     if (eap->cmdidx == CMD_endwhile)
1256     {
1257 	err = e_while;
1258 	csf = CSF_WHILE;
1259     }
1260     else
1261     {
1262 	err = e_for;
1263 	csf = CSF_FOR;
1264     }
1265 
1266     if (cstack->cs_looplevel <= 0 || cstack->cs_idx < 0)
1267 	eap->errmsg = _(err);
1268     else
1269     {
1270 	fl =  cstack->cs_flags[cstack->cs_idx];
1271 	if (!(fl & csf))
1272 	{
1273 	    // If we are in a ":while" or ":for" but used the wrong endloop
1274 	    // command, do not rewind to the next enclosing ":for"/":while".
1275 	    if (fl & CSF_WHILE)
1276 		eap->errmsg = _("E732: Using :endfor with :while");
1277 	    else if (fl & CSF_FOR)
1278 		eap->errmsg = _("E733: Using :endwhile with :for");
1279 	}
1280 	if (!(fl & (CSF_WHILE | CSF_FOR)))
1281 	{
1282 	    if (!(fl & CSF_TRY))
1283 		eap->errmsg = _(e_endif);
1284 	    else if (fl & CSF_FINALLY)
1285 		eap->errmsg = _(e_endtry);
1286 	    // Try to find the matching ":while" and report what's missing.
1287 	    for (idx = cstack->cs_idx; idx > 0; --idx)
1288 	    {
1289 		fl =  cstack->cs_flags[idx];
1290 		if ((fl & CSF_TRY) && !(fl & CSF_FINALLY))
1291 		{
1292 		    // Give up at a try conditional not in its finally clause.
1293 		    // Ignore the ":endwhile"/":endfor".
1294 		    eap->errmsg = _(err);
1295 		    return;
1296 		}
1297 		if (fl & csf)
1298 		    break;
1299 	    }
1300 	    // Cleanup and rewind all contained (and unclosed) conditionals.
1301 	    (void)cleanup_conditionals(cstack, CSF_WHILE | CSF_FOR, FALSE);
1302 	    rewind_conditionals(cstack, idx, CSF_TRY, &cstack->cs_trylevel);
1303 	}
1304 
1305 	/*
1306 	 * When debugging or a breakpoint was encountered, display the debug
1307 	 * prompt (if not already done).  This shows the user that an
1308 	 * ":endwhile"/":endfor" is executed when the ":while" was not TRUE or
1309 	 * after a ":break".  Handle a ">quit" debug command as if an
1310 	 * interrupt had occurred before the ":endwhile"/":endfor".  That is,
1311 	 * throw an interrupt exception if appropriate.  Doing this here
1312 	 * prevents that an exception for a parsing error is discarded when
1313 	 * throwing the interrupt exception later on.
1314 	 */
1315 	else if (cstack->cs_flags[cstack->cs_idx] & CSF_TRUE
1316 		&& !(cstack->cs_flags[cstack->cs_idx] & CSF_ACTIVE)
1317 		&& dbg_check_skipped(eap))
1318 	    (void)do_intthrow(cstack);
1319 
1320 	/*
1321 	 * Set loop flag, so do_cmdline() will jump back to the matching
1322 	 * ":while" or ":for".
1323 	 */
1324 	cstack->cs_lflags |= CSL_HAD_ENDLOOP;
1325     }
1326 }
1327 
1328 
1329 /*
1330  * ":throw expr"
1331  */
1332     void
1333 ex_throw(exarg_T *eap)
1334 {
1335     char_u	*arg = eap->arg;
1336     char_u	*value;
1337 
1338     if (*arg != NUL && *arg != '|' && *arg != '\n')
1339 	value = eval_to_string_skip(arg, eap, eap->skip);
1340     else
1341     {
1342 	emsg(_(e_argreq));
1343 	value = NULL;
1344     }
1345 
1346     // On error or when an exception is thrown during argument evaluation, do
1347     // not throw.
1348     if (!eap->skip && value != NULL)
1349     {
1350 	if (throw_exception(value, ET_USER, NULL) == FAIL)
1351 	    vim_free(value);
1352 	else
1353 	    do_throw(eap->cstack);
1354     }
1355 }
1356 
1357 /*
1358  * Throw the current exception through the specified cstack.  Common routine
1359  * for ":throw" (user exception) and error and interrupt exceptions.  Also
1360  * used for rethrowing an uncaught exception.
1361  */
1362     void
1363 do_throw(cstack_T *cstack)
1364 {
1365     int		idx;
1366     int		inactivate_try = FALSE;
1367 
1368     /*
1369      * Cleanup and inactivate up to the next surrounding try conditional that
1370      * is not in its finally clause.  Normally, do not inactivate the try
1371      * conditional itself, so that its ACTIVE flag can be tested below.  But
1372      * if a previous error or interrupt has not been converted to an exception,
1373      * inactivate the try conditional, too, as if the conversion had been done,
1374      * and reset the did_emsg or got_int flag, so this won't happen again at
1375      * the next surrounding try conditional.
1376      */
1377 #ifndef THROW_ON_ERROR_TRUE
1378     if (did_emsg && !THROW_ON_ERROR)
1379     {
1380 	inactivate_try = TRUE;
1381 	did_emsg = FALSE;
1382     }
1383 #endif
1384 #ifndef THROW_ON_INTERRUPT_TRUE
1385     if (got_int && !THROW_ON_INTERRUPT)
1386     {
1387 	inactivate_try = TRUE;
1388 	got_int = FALSE;
1389     }
1390 #endif
1391     idx = cleanup_conditionals(cstack, 0, inactivate_try);
1392     if (idx >= 0)
1393     {
1394 	/*
1395 	 * If this try conditional is active and we are before its first
1396 	 * ":catch", set THROWN so that the ":catch" commands will check
1397 	 * whether the exception matches.  When the exception came from any of
1398 	 * the catch clauses, it will be made pending at the ":finally" (if
1399 	 * present) and rethrown at the ":endtry".  This will also happen if
1400 	 * the try conditional is inactive.  This is the case when we are
1401 	 * throwing an exception due to an error or interrupt on the way from
1402 	 * a preceding ":continue", ":break", ":return", ":finish", error or
1403 	 * interrupt (not converted to an exception) to the finally clause or
1404 	 * from a preceding throw of a user or error or interrupt exception to
1405 	 * the matching catch clause or the finally clause.
1406 	 */
1407 	if (!(cstack->cs_flags[idx] & CSF_CAUGHT))
1408 	{
1409 	    if (cstack->cs_flags[idx] & CSF_ACTIVE)
1410 		cstack->cs_flags[idx] |= CSF_THROWN;
1411 	    else
1412 		// THROWN may have already been set for a catchable exception
1413 		// that has been discarded.  Ensure it is reset for the new
1414 		// exception.
1415 		cstack->cs_flags[idx] &= ~CSF_THROWN;
1416 	}
1417 	cstack->cs_flags[idx] &= ~CSF_ACTIVE;
1418 	cstack->cs_exception[idx] = current_exception;
1419     }
1420 #if 0
1421     // TODO: Add optimization below.  Not yet done because of interface
1422     // problems to eval.c and ex_cmds2.c. (Servatius)
1423     else
1424     {
1425 	/*
1426 	 * There are no catch clauses to check or finally clauses to execute.
1427 	 * End the current script or function.  The exception will be rethrown
1428 	 * in the caller.
1429 	 */
1430 	if (getline_equal(eap->getline, eap->cookie, get_func_line))
1431 	    current_funccal->returned = TRUE;
1432 	elseif (eap->get_func_line == getsourceline)
1433 	    ((struct source_cookie *)eap->cookie)->finished = TRUE;
1434     }
1435 #endif
1436 
1437     did_throw = TRUE;
1438 }
1439 
1440 /*
1441  * ":try"
1442  */
1443     void
1444 ex_try(exarg_T *eap)
1445 {
1446     int		skip;
1447     cstack_T	*cstack = eap->cstack;
1448 
1449     if (cstack->cs_idx == CSTACK_LEN - 1)
1450 	eap->errmsg = _("E601: :try nesting too deep");
1451     else
1452     {
1453 	++cstack->cs_idx;
1454 	++cstack->cs_trylevel;
1455 	cstack->cs_flags[cstack->cs_idx] = CSF_TRY;
1456 	cstack->cs_pending[cstack->cs_idx] = CSTP_NONE;
1457 
1458 	/*
1459 	 * Don't do something after an error, interrupt, or throw, or when there
1460 	 * is a surrounding conditional and it was not active.
1461 	 */
1462 	skip = did_emsg || got_int || did_throw || (cstack->cs_idx > 0
1463 		&& !(cstack->cs_flags[cstack->cs_idx - 1] & CSF_ACTIVE));
1464 
1465 	if (!skip)
1466 	{
1467 	    // Set ACTIVE and TRUE.  TRUE means that the corresponding ":catch"
1468 	    // commands should check for a match if an exception is thrown and
1469 	    // that the finally clause needs to be executed.
1470 	    cstack->cs_flags[cstack->cs_idx] |= CSF_ACTIVE | CSF_TRUE;
1471 
1472 	    /*
1473 	     * ":silent!", even when used in a try conditional, disables
1474 	     * displaying of error messages and conversion of errors to
1475 	     * exceptions.  When the silent commands again open a try
1476 	     * conditional, save "emsg_silent" and reset it so that errors are
1477 	     * again converted to exceptions.  The value is restored when that
1478 	     * try conditional is left.  If it is left normally, the commands
1479 	     * following the ":endtry" are again silent.  If it is left by
1480 	     * a ":continue", ":break", ":return", or ":finish", the commands
1481 	     * executed next are again silent.  If it is left due to an
1482 	     * aborting error, an interrupt, or an exception, restoring
1483 	     * "emsg_silent" does not matter since we are already in the
1484 	     * aborting state and/or the exception has already been thrown.
1485 	     * The effect is then just freeing the memory that was allocated
1486 	     * to save the value.
1487 	     */
1488 	    if (emsg_silent)
1489 	    {
1490 		eslist_T	*elem;
1491 
1492 		elem = ALLOC_ONE(struct eslist_elem);
1493 		if (elem == NULL)
1494 		    emsg(_(e_outofmem));
1495 		else
1496 		{
1497 		    elem->saved_emsg_silent = emsg_silent;
1498 		    elem->next = cstack->cs_emsg_silent_list;
1499 		    cstack->cs_emsg_silent_list = elem;
1500 		    cstack->cs_flags[cstack->cs_idx] |= CSF_SILENT;
1501 		    emsg_silent = 0;
1502 		}
1503 	    }
1504 	}
1505 
1506     }
1507 }
1508 
1509 /*
1510  * ":catch /{pattern}/" and ":catch"
1511  */
1512     void
1513 ex_catch(exarg_T *eap)
1514 {
1515     int		idx = 0;
1516     int		give_up = FALSE;
1517     int		skip = FALSE;
1518     int		caught = FALSE;
1519     char_u	*end;
1520     int		save_char = 0;
1521     char_u	*save_cpo;
1522     regmatch_T	regmatch;
1523     int		prev_got_int;
1524     cstack_T	*cstack = eap->cstack;
1525     char_u	*pat;
1526 
1527     if (cstack->cs_trylevel <= 0 || cstack->cs_idx < 0)
1528     {
1529 	eap->errmsg = _(e_catch);
1530 	give_up = TRUE;
1531     }
1532     else
1533     {
1534 	if (!(cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
1535 	{
1536 	    // Report what's missing if the matching ":try" is not in its
1537 	    // finally clause.
1538 	    eap->errmsg = get_end_emsg(cstack);
1539 	    skip = TRUE;
1540 	}
1541 	for (idx = cstack->cs_idx; idx > 0; --idx)
1542 	    if (cstack->cs_flags[idx] & CSF_TRY)
1543 		break;
1544 	if (cstack->cs_flags[idx] & CSF_FINALLY)
1545 	{
1546 	    // Give up for a ":catch" after ":finally" and ignore it.
1547 	    // Just parse.
1548 	    eap->errmsg = _("E604: :catch after :finally");
1549 	    give_up = TRUE;
1550 	}
1551 	else
1552 	    rewind_conditionals(cstack, idx, CSF_WHILE | CSF_FOR,
1553 						       &cstack->cs_looplevel);
1554     }
1555 
1556     if (ends_excmd2(eap->cmd, eap->arg))   // no argument, catch all errors
1557     {
1558 	pat = (char_u *)".*";
1559 	end = NULL;
1560 	eap->nextcmd = find_nextcmd(eap->arg);
1561     }
1562     else
1563     {
1564 	pat = eap->arg + 1;
1565 	end = skip_regexp_err(pat, *eap->arg, TRUE);
1566 	if (end == NULL)
1567 	    give_up = TRUE;
1568     }
1569 
1570     if (!give_up)
1571     {
1572 	/*
1573 	 * Don't do something when no exception has been thrown or when the
1574 	 * corresponding try block never got active (because of an inactive
1575 	 * surrounding conditional or after an error or interrupt or throw).
1576 	 */
1577 	if (!did_throw || !(cstack->cs_flags[idx] & CSF_TRUE))
1578 	    skip = TRUE;
1579 
1580 	/*
1581 	 * Check for a match only if an exception is thrown but not caught by
1582 	 * a previous ":catch".  An exception that has replaced a discarded
1583 	 * exception is not checked (THROWN is not set then).
1584 	 */
1585 	if (!skip && (cstack->cs_flags[idx] & CSF_THROWN)
1586 		&& !(cstack->cs_flags[idx] & CSF_CAUGHT))
1587 	{
1588 	    if (end != NULL && *end != NUL
1589 				      && !ends_excmd2(end, skipwhite(end + 1)))
1590 	    {
1591 		semsg(_(e_trailing_arg), end);
1592 		return;
1593 	    }
1594 
1595 	    // When debugging or a breakpoint was encountered, display the
1596 	    // debug prompt (if not already done) before checking for a match.
1597 	    // This is a helpful hint for the user when the regular expression
1598 	    // matching fails.  Handle a ">quit" debug command as if an
1599 	    // interrupt had occurred before the ":catch".  That is, discard
1600 	    // the original exception, replace it by an interrupt exception,
1601 	    // and don't catch it in this try block.
1602 	    if (!dbg_check_skipped(eap) || !do_intthrow(cstack))
1603 	    {
1604 		// Terminate the pattern and avoid the 'l' flag in 'cpoptions'
1605 		// while compiling it.
1606 		if (end != NULL)
1607 		{
1608 		    save_char = *end;
1609 		    *end = NUL;
1610 		}
1611 		save_cpo  = p_cpo;
1612 		p_cpo = (char_u *)"";
1613 		// Disable error messages, it will make current_exception
1614 		// invalid.
1615 		++emsg_off;
1616 		regmatch.regprog = vim_regcomp(pat, RE_MAGIC + RE_STRING);
1617 		--emsg_off;
1618 		regmatch.rm_ic = FALSE;
1619 		if (end != NULL)
1620 		    *end = save_char;
1621 		p_cpo = save_cpo;
1622 		if (regmatch.regprog == NULL)
1623 		    semsg(_(e_invarg2), pat);
1624 		else
1625 		{
1626 		    /*
1627 		     * Save the value of got_int and reset it.  We don't want
1628 		     * a previous interruption cancel matching, only hitting
1629 		     * CTRL-C while matching should abort it.
1630 		     */
1631 		    prev_got_int = got_int;
1632 		    got_int = FALSE;
1633 		    caught = vim_regexec_nl(&regmatch,
1634 			       (char_u *)current_exception->value, (colnr_T)0);
1635 		    got_int |= prev_got_int;
1636 		    vim_regfree(regmatch.regprog);
1637 		}
1638 	    }
1639 	}
1640 
1641 	if (caught)
1642 	{
1643 	    // Make this ":catch" clause active and reset did_emsg, got_int,
1644 	    // and did_throw.  Put the exception on the caught stack.
1645 	    cstack->cs_flags[idx] |= CSF_ACTIVE | CSF_CAUGHT;
1646 	    did_emsg = got_int = did_throw = FALSE;
1647 	    catch_exception((except_T *)cstack->cs_exception[idx]);
1648 	    // It's mandatory that the current exception is stored in the cstack
1649 	    // so that it can be discarded at the next ":catch", ":finally", or
1650 	    // ":endtry" or when the catch clause is left by a ":continue",
1651 	    // ":break", ":return", ":finish", error, interrupt, or another
1652 	    // exception.
1653 	    if (cstack->cs_exception[cstack->cs_idx] != current_exception)
1654 		internal_error("ex_catch()");
1655 	}
1656 	else
1657 	{
1658 	    /*
1659 	     * If there is a preceding catch clause and it caught the exception,
1660 	     * finish the exception now.  This happens also after errors except
1661 	     * when this ":catch" was after the ":finally" or not within
1662 	     * a ":try".  Make the try conditional inactive so that the
1663 	     * following catch clauses are skipped.  On an error or interrupt
1664 	     * after the preceding try block or catch clause was left by
1665 	     * a ":continue", ":break", ":return", or ":finish", discard the
1666 	     * pending action.
1667 	     */
1668 	    cleanup_conditionals(cstack, CSF_TRY, TRUE);
1669 	}
1670     }
1671 
1672     if (end != NULL)
1673 	eap->nextcmd = find_nextcmd(end);
1674 }
1675 
1676 /*
1677  * ":finally"
1678  */
1679     void
1680 ex_finally(exarg_T *eap)
1681 {
1682     int		idx;
1683     int		skip = FALSE;
1684     int		pending = CSTP_NONE;
1685     cstack_T	*cstack = eap->cstack;
1686 
1687     if (cstack->cs_trylevel <= 0 || cstack->cs_idx < 0)
1688 	eap->errmsg = _(e_finally);
1689     else
1690     {
1691 	if (!(cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
1692 	{
1693 	    eap->errmsg = get_end_emsg(cstack);
1694 	    for (idx = cstack->cs_idx - 1; idx > 0; --idx)
1695 		if (cstack->cs_flags[idx] & CSF_TRY)
1696 		    break;
1697 	    // Make this error pending, so that the commands in the following
1698 	    // finally clause can be executed.  This overrules also a pending
1699 	    // ":continue", ":break", ":return", or ":finish".
1700 	    pending = CSTP_ERROR;
1701 	}
1702 	else
1703 	    idx = cstack->cs_idx;
1704 
1705 	if (cstack->cs_flags[idx] & CSF_FINALLY)
1706 	{
1707 	    // Give up for a multiple ":finally" and ignore it.
1708 	    eap->errmsg = _(e_finally_dup);
1709 	    return;
1710 	}
1711 	rewind_conditionals(cstack, idx, CSF_WHILE | CSF_FOR,
1712 						       &cstack->cs_looplevel);
1713 
1714 	/*
1715 	 * Don't do something when the corresponding try block never got active
1716 	 * (because of an inactive surrounding conditional or after an error or
1717 	 * interrupt or throw) or for a ":finally" without ":try" or a multiple
1718 	 * ":finally".  After every other error (did_emsg or the conditional
1719 	 * errors detected above) or after an interrupt (got_int) or an
1720 	 * exception (did_throw), the finally clause must be executed.
1721 	 */
1722 	skip = !(cstack->cs_flags[cstack->cs_idx] & CSF_TRUE);
1723 
1724 	if (!skip)
1725 	{
1726 	    // When debugging or a breakpoint was encountered, display the
1727 	    // debug prompt (if not already done).  The user then knows that the
1728 	    // finally clause is executed.
1729 	    if (dbg_check_skipped(eap))
1730 	    {
1731 		// Handle a ">quit" debug command as if an interrupt had
1732 		// occurred before the ":finally".  That is, discard the
1733 		// original exception and replace it by an interrupt
1734 		// exception.
1735 		(void)do_intthrow(cstack);
1736 	    }
1737 
1738 	    /*
1739 	     * If there is a preceding catch clause and it caught the exception,
1740 	     * finish the exception now.  This happens also after errors except
1741 	     * when this is a multiple ":finally" or one not within a ":try".
1742 	     * After an error or interrupt, this also discards a pending
1743 	     * ":continue", ":break", ":finish", or ":return" from the preceding
1744 	     * try block or catch clause.
1745 	     */
1746 	    cleanup_conditionals(cstack, CSF_TRY, FALSE);
1747 
1748 	    /*
1749 	     * Make did_emsg, got_int, did_throw pending.  If set, they overrule
1750 	     * a pending ":continue", ":break", ":return", or ":finish".  Then
1751 	     * we have particularly to discard a pending return value (as done
1752 	     * by the call to cleanup_conditionals() above when did_emsg or
1753 	     * got_int is set).  The pending values are restored by the
1754 	     * ":endtry", except if there is a new error, interrupt, exception,
1755 	     * ":continue", ":break", ":return", or ":finish" in the following
1756 	     * finally clause.  A missing ":endwhile", ":endfor" or ":endif"
1757 	     * detected here is treated as if did_emsg and did_throw had
1758 	     * already been set, respectively in case that the error is not
1759 	     * converted to an exception, did_throw had already been unset.
1760 	     * We must not set did_emsg here since that would suppress the
1761 	     * error message.
1762 	     */
1763 	    if (pending == CSTP_ERROR || did_emsg || got_int || did_throw)
1764 	    {
1765 		if (cstack->cs_pending[cstack->cs_idx] == CSTP_RETURN)
1766 		{
1767 		    report_discard_pending(CSTP_RETURN,
1768 					   cstack->cs_rettv[cstack->cs_idx]);
1769 		    discard_pending_return(cstack->cs_rettv[cstack->cs_idx]);
1770 		}
1771 		if (pending == CSTP_ERROR && !did_emsg)
1772 		    pending |= (THROW_ON_ERROR) ? CSTP_THROW : 0;
1773 		else
1774 		    pending |= did_throw ? CSTP_THROW : 0;
1775 		pending |= did_emsg  ? CSTP_ERROR     : 0;
1776 		pending |= got_int   ? CSTP_INTERRUPT : 0;
1777 		cstack->cs_pending[cstack->cs_idx] = pending;
1778 
1779 		// It's mandatory that the current exception is stored in the
1780 		// cstack so that it can be rethrown at the ":endtry" or be
1781 		// discarded if the finally clause is left by a ":continue",
1782 		// ":break", ":return", ":finish", error, interrupt, or another
1783 		// exception.  When emsg() is called for a missing ":endif" or
1784 		// a missing ":endwhile"/":endfor" detected here, the
1785 		// exception will be discarded.
1786 		if (did_throw && cstack->cs_exception[cstack->cs_idx]
1787 							 != current_exception)
1788 		    internal_error("ex_finally()");
1789 	    }
1790 
1791 	    /*
1792 	     * Set CSL_HAD_FINA, so do_cmdline() will reset did_emsg,
1793 	     * got_int, and did_throw and make the finally clause active.
1794 	     * This will happen after emsg() has been called for a missing
1795 	     * ":endif" or a missing ":endwhile"/":endfor" detected here, so
1796 	     * that the following finally clause will be executed even then.
1797 	     */
1798 	    cstack->cs_lflags |= CSL_HAD_FINA;
1799 	}
1800     }
1801 }
1802 
1803 /*
1804  * ":endtry"
1805  */
1806     void
1807 ex_endtry(exarg_T *eap)
1808 {
1809     int		idx;
1810     int		skip;
1811     int		rethrow = FALSE;
1812     int		pending = CSTP_NONE;
1813     void	*rettv = NULL;
1814     cstack_T	*cstack = eap->cstack;
1815 
1816     if (cstack->cs_trylevel <= 0 || cstack->cs_idx < 0)
1817 	eap->errmsg = _(e_no_endtry);
1818     else
1819     {
1820 	/*
1821 	 * Don't do something after an error, interrupt or throw in the try
1822 	 * block, catch clause, or finally clause preceding this ":endtry" or
1823 	 * when an error or interrupt occurred after a ":continue", ":break",
1824 	 * ":return", or ":finish" in a try block or catch clause preceding this
1825 	 * ":endtry" or when the try block never got active (because of an
1826 	 * inactive surrounding conditional or after an error or interrupt or
1827 	 * throw) or when there is a surrounding conditional and it has been
1828 	 * made inactive by a ":continue", ":break", ":return", or ":finish" in
1829 	 * the finally clause.  The latter case need not be tested since then
1830 	 * anything pending has already been discarded. */
1831 	skip = did_emsg || got_int || did_throw ||
1832 	    !(cstack->cs_flags[cstack->cs_idx] & CSF_TRUE);
1833 
1834 	if (!(cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
1835 	{
1836 	    eap->errmsg = get_end_emsg(cstack);
1837 	    // Find the matching ":try" and report what's missing.
1838 	    idx = cstack->cs_idx;
1839 	    do
1840 		--idx;
1841 	    while (idx > 0 && !(cstack->cs_flags[idx] & CSF_TRY));
1842 	    rewind_conditionals(cstack, idx, CSF_WHILE | CSF_FOR,
1843 						       &cstack->cs_looplevel);
1844 	    skip = TRUE;
1845 
1846 	    /*
1847 	     * If an exception is being thrown, discard it to prevent it from
1848 	     * being rethrown at the end of this function.  It would be
1849 	     * discarded by the error message, anyway.  Resets did_throw.
1850 	     * This does not affect the script termination due to the error
1851 	     * since "trylevel" is decremented after emsg() has been called.
1852 	     */
1853 	    if (did_throw)
1854 		discard_current_exception();
1855 	}
1856 	else
1857 	{
1858 	    idx = cstack->cs_idx;
1859 
1860 	    /*
1861 	     * If we stopped with the exception currently being thrown at this
1862 	     * try conditional since we didn't know that it doesn't have
1863 	     * a finally clause, we need to rethrow it after closing the try
1864 	     * conditional.
1865 	     */
1866 	    if (did_throw && (cstack->cs_flags[idx] & CSF_TRUE)
1867 		    && !(cstack->cs_flags[idx] & CSF_FINALLY))
1868 		rethrow = TRUE;
1869 	}
1870 
1871 	// If there was no finally clause, show the user when debugging or
1872 	// a breakpoint was encountered that the end of the try conditional has
1873 	// been reached: display the debug prompt (if not already done).  Do
1874 	// this on normal control flow or when an exception was thrown, but not
1875 	// on an interrupt or error not converted to an exception or when
1876 	// a ":break", ":continue", ":return", or ":finish" is pending.  These
1877 	// actions are carried out immediately.
1878 	if ((rethrow || (!skip
1879 			&& !(cstack->cs_flags[idx] & CSF_FINALLY)
1880 			&& !cstack->cs_pending[idx]))
1881 		&& dbg_check_skipped(eap))
1882 	{
1883 	    // Handle a ">quit" debug command as if an interrupt had occurred
1884 	    // before the ":endtry".  That is, throw an interrupt exception and
1885 	    // set "skip" and "rethrow".
1886 	    if (got_int)
1887 	    {
1888 		skip = TRUE;
1889 		(void)do_intthrow(cstack);
1890 		// The do_intthrow() call may have reset did_throw or
1891 		// cstack->cs_pending[idx].
1892 		rethrow = FALSE;
1893 		if (did_throw && !(cstack->cs_flags[idx] & CSF_FINALLY))
1894 		    rethrow = TRUE;
1895 	    }
1896 	}
1897 
1898 	/*
1899 	 * If a ":return" is pending, we need to resume it after closing the
1900 	 * try conditional; remember the return value.  If there was a finally
1901 	 * clause making an exception pending, we need to rethrow it.  Make it
1902 	 * the exception currently being thrown.
1903 	 */
1904 	if (!skip)
1905 	{
1906 	    pending = cstack->cs_pending[idx];
1907 	    cstack->cs_pending[idx] = CSTP_NONE;
1908 	    if (pending == CSTP_RETURN)
1909 		rettv = cstack->cs_rettv[idx];
1910 	    else if (pending & CSTP_THROW)
1911 		current_exception = cstack->cs_exception[idx];
1912 	}
1913 
1914 	/*
1915 	 * Discard anything pending on an error, interrupt, or throw in the
1916 	 * finally clause.  If there was no ":finally", discard a pending
1917 	 * ":continue", ":break", ":return", or ":finish" if an error or
1918 	 * interrupt occurred afterwards, but before the ":endtry" was reached.
1919 	 * If an exception was caught by the last of the catch clauses and there
1920 	 * was no finally clause, finish the exception now.  This happens also
1921 	 * after errors except when this ":endtry" is not within a ":try".
1922 	 * Restore "emsg_silent" if it has been reset by this try conditional.
1923 	 */
1924 	(void)cleanup_conditionals(cstack, CSF_TRY | CSF_SILENT, TRUE);
1925 
1926 	--cstack->cs_idx;
1927 	--cstack->cs_trylevel;
1928 
1929 	if (!skip)
1930 	{
1931 	    report_resume_pending(pending,
1932 		    (pending == CSTP_RETURN) ? rettv :
1933 		    (pending & CSTP_THROW) ? (void *)current_exception : NULL);
1934 	    switch (pending)
1935 	    {
1936 		case CSTP_NONE:
1937 		    break;
1938 
1939 		// Reactivate a pending ":continue", ":break", ":return",
1940 		// ":finish" from the try block or a catch clause of this try
1941 		// conditional.  This is skipped, if there was an error in an
1942 		// (unskipped) conditional command or an interrupt afterwards
1943 		// or if the finally clause is present and executed a new error,
1944 		// interrupt, throw, ":continue", ":break", ":return", or
1945 		// ":finish".
1946 		case CSTP_CONTINUE:
1947 		    ex_continue(eap);
1948 		    break;
1949 		case CSTP_BREAK:
1950 		    ex_break(eap);
1951 		    break;
1952 		case CSTP_RETURN:
1953 		    do_return(eap, FALSE, FALSE, rettv);
1954 		    break;
1955 		case CSTP_FINISH:
1956 		    do_finish(eap, FALSE);
1957 		    break;
1958 
1959 		// When the finally clause was entered due to an error,
1960 		// interrupt or throw (as opposed to a ":continue", ":break",
1961 		// ":return", or ":finish"), restore the pending values of
1962 		// did_emsg, got_int, and did_throw.  This is skipped, if there
1963 		// was a new error, interrupt, throw, ":continue", ":break",
1964 		// ":return", or ":finish".  in the finally clause.
1965 		default:
1966 		    if (pending & CSTP_ERROR)
1967 			did_emsg = TRUE;
1968 		    if (pending & CSTP_INTERRUPT)
1969 			got_int = TRUE;
1970 		    if (pending & CSTP_THROW)
1971 			rethrow = TRUE;
1972 		    break;
1973 	    }
1974 	}
1975 
1976 	if (rethrow)
1977 	    // Rethrow the current exception (within this cstack).
1978 	    do_throw(cstack);
1979     }
1980 }
1981 
1982 /*
1983  * enter_cleanup() and leave_cleanup()
1984  *
1985  * Functions to be called before/after invoking a sequence of autocommands for
1986  * cleanup for a failed command.  (Failure means here that a call to emsg()
1987  * has been made, an interrupt occurred, or there is an uncaught exception
1988  * from a previous autocommand execution of the same command.)
1989  *
1990  * Call enter_cleanup() with a pointer to a cleanup_T and pass the same
1991  * pointer to leave_cleanup().  The cleanup_T structure stores the pending
1992  * error/interrupt/exception state.
1993  */
1994 
1995 /*
1996  * This function works a bit like ex_finally() except that there was not
1997  * actually an extra try block around the part that failed and an error or
1998  * interrupt has not (yet) been converted to an exception.  This function
1999  * saves the error/interrupt/ exception state and prepares for the call to
2000  * do_cmdline() that is going to be made for the cleanup autocommand
2001  * execution.
2002  */
2003     void
2004 enter_cleanup(cleanup_T *csp)
2005 {
2006     int		pending = CSTP_NONE;
2007 
2008     /*
2009      * Postpone did_emsg, got_int, did_throw.  The pending values will be
2010      * restored by leave_cleanup() except if there was an aborting error,
2011      * interrupt, or uncaught exception after this function ends.
2012      */
2013     if (did_emsg || got_int || did_throw || need_rethrow)
2014     {
2015 	csp->pending = (did_emsg     ? CSTP_ERROR     : 0)
2016 		     | (got_int      ? CSTP_INTERRUPT : 0)
2017 		     | (did_throw    ? CSTP_THROW     : 0)
2018 		     | (need_rethrow ? CSTP_THROW     : 0);
2019 
2020 	// If we are currently throwing an exception (did_throw), save it as
2021 	// well.  On an error not yet converted to an exception, update
2022 	// "force_abort" and reset "cause_abort" (as do_errthrow() would do).
2023 	// This is needed for the do_cmdline() call that is going to be made
2024 	// for autocommand execution.  We need not save *msg_list because
2025 	// there is an extra instance for every call of do_cmdline(), anyway.
2026 	if (did_throw || need_rethrow)
2027 	{
2028 	    csp->exception = current_exception;
2029 	    current_exception = NULL;
2030 	}
2031 	else
2032 	{
2033 	    csp->exception = NULL;
2034 	    if (did_emsg)
2035 	    {
2036 		force_abort |= cause_abort;
2037 		cause_abort = FALSE;
2038 	    }
2039 	}
2040 	did_emsg = got_int = did_throw = need_rethrow = FALSE;
2041 
2042 	// Report if required by the 'verbose' option or when debugging.
2043 	report_make_pending(pending, csp->exception);
2044     }
2045     else
2046     {
2047 	csp->pending = CSTP_NONE;
2048 	csp->exception = NULL;
2049     }
2050 }
2051 
2052 /*
2053  * See comment above enter_cleanup() for how this function is used.
2054  *
2055  * This function is a bit like ex_endtry() except that there was not actually
2056  * an extra try block around the part that failed and an error or interrupt
2057  * had not (yet) been converted to an exception when the cleanup autocommand
2058  * sequence was invoked.
2059  *
2060  * This function has to be called with the address of the cleanup_T structure
2061  * filled by enter_cleanup() as an argument; it restores the error/interrupt/
2062  * exception state saved by that function - except there was an aborting
2063  * error, an interrupt or an uncaught exception during execution of the
2064  * cleanup autocommands.  In the latter case, the saved error/interrupt/
2065  * exception state is discarded.
2066  */
2067     void
2068 leave_cleanup(cleanup_T *csp)
2069 {
2070     int		pending = csp->pending;
2071 
2072     if (pending == CSTP_NONE)	// nothing to do
2073 	return;
2074 
2075     // If there was an aborting error, an interrupt, or an uncaught exception
2076     // after the corresponding call to enter_cleanup(), discard what has been
2077     // made pending by it.  Report this to the user if required by the
2078     // 'verbose' option or when debugging.
2079     if (aborting() || need_rethrow)
2080     {
2081 	if (pending & CSTP_THROW)
2082 	    // Cancel the pending exception (includes report).
2083 	    discard_exception((except_T *)csp->exception, FALSE);
2084 	else
2085 	    report_discard_pending(pending, NULL);
2086 
2087 	// If an error was about to be converted to an exception when
2088 	// enter_cleanup() was called, free the message list.
2089 	if (msg_list != NULL)
2090 	    free_global_msglist();
2091     }
2092 
2093     /*
2094      * If there was no new error, interrupt, or throw between the calls
2095      * to enter_cleanup() and leave_cleanup(), restore the pending
2096      * error/interrupt/exception state.
2097      */
2098     else
2099     {
2100 	/*
2101 	 * If there was an exception being thrown when enter_cleanup() was
2102 	 * called, we need to rethrow it.  Make it the exception currently
2103 	 * being thrown.
2104 	 */
2105 	if (pending & CSTP_THROW)
2106 	    current_exception = csp->exception;
2107 
2108 	/*
2109 	 * If an error was about to be converted to an exception when
2110 	 * enter_cleanup() was called, let "cause_abort" take the part of
2111 	 * "force_abort" (as done by cause_errthrow()).
2112 	 */
2113 	else if (pending & CSTP_ERROR)
2114 	{
2115 	    cause_abort = force_abort;
2116 	    force_abort = FALSE;
2117 	}
2118 
2119 	/*
2120 	 * Restore the pending values of did_emsg, got_int, and did_throw.
2121 	 */
2122 	if (pending & CSTP_ERROR)
2123 	    did_emsg = TRUE;
2124 	if (pending & CSTP_INTERRUPT)
2125 	    got_int = TRUE;
2126 	if (pending & CSTP_THROW)
2127 	    need_rethrow = TRUE;    // did_throw will be set by do_one_cmd()
2128 
2129 	// Report if required by the 'verbose' option or when debugging.
2130 	report_resume_pending(pending,
2131 		   (pending & CSTP_THROW) ? (void *)current_exception : NULL);
2132     }
2133 }
2134 
2135 
2136 /*
2137  * Make conditionals inactive and discard what's pending in finally clauses
2138  * until the conditional type searched for or a try conditional not in its
2139  * finally clause is reached.  If this is in an active catch clause, finish
2140  * the caught exception.
2141  * Return the cstack index where the search stopped.
2142  * Values used for "searched_cond" are (CSF_WHILE | CSF_FOR) or CSF_TRY or 0,
2143  * the latter meaning the innermost try conditional not in its finally clause.
2144  * "inclusive" tells whether the conditional searched for should be made
2145  * inactive itself (a try conditional not in its finally clause possibly find
2146  * before is always made inactive).  If "inclusive" is TRUE and
2147  * "searched_cond" is CSF_TRY|CSF_SILENT, the saved former value of
2148  * "emsg_silent", if reset when the try conditional finally reached was
2149  * entered, is restored (used by ex_endtry()).  This is normally done only
2150  * when such a try conditional is left.
2151  */
2152     int
2153 cleanup_conditionals(
2154     cstack_T   *cstack,
2155     int		searched_cond,
2156     int		inclusive)
2157 {
2158     int		idx;
2159     int		stop = FALSE;
2160 
2161     for (idx = cstack->cs_idx; idx >= 0; --idx)
2162     {
2163 	if (cstack->cs_flags[idx] & CSF_TRY)
2164 	{
2165 	    /*
2166 	     * Discard anything pending in a finally clause and continue the
2167 	     * search.  There may also be a pending ":continue", ":break",
2168 	     * ":return", or ":finish" before the finally clause.  We must not
2169 	     * discard it, unless an error or interrupt occurred afterwards.
2170 	     */
2171 	    if (did_emsg || got_int || (cstack->cs_flags[idx] & CSF_FINALLY))
2172 	    {
2173 		switch (cstack->cs_pending[idx])
2174 		{
2175 		    case CSTP_NONE:
2176 			break;
2177 
2178 		    case CSTP_CONTINUE:
2179 		    case CSTP_BREAK:
2180 		    case CSTP_FINISH:
2181 			report_discard_pending(cstack->cs_pending[idx], NULL);
2182 			cstack->cs_pending[idx] = CSTP_NONE;
2183 			break;
2184 
2185 		    case CSTP_RETURN:
2186 			report_discard_pending(CSTP_RETURN,
2187 						      cstack->cs_rettv[idx]);
2188 			discard_pending_return(cstack->cs_rettv[idx]);
2189 			cstack->cs_pending[idx] = CSTP_NONE;
2190 			break;
2191 
2192 		    default:
2193 			if (cstack->cs_flags[idx] & CSF_FINALLY)
2194 			{
2195 			    if (cstack->cs_pending[idx] & CSTP_THROW)
2196 			    {
2197 				// Cancel the pending exception.  This is in the
2198 				// finally clause, so that the stack of the
2199 				// caught exceptions is not involved.
2200 				discard_exception((except_T *)
2201 					cstack->cs_exception[idx],
2202 					FALSE);
2203 			    }
2204 			    else
2205 				report_discard_pending(cstack->cs_pending[idx],
2206 					NULL);
2207 			    cstack->cs_pending[idx] = CSTP_NONE;
2208 			}
2209 			break;
2210 		}
2211 	    }
2212 
2213 	    /*
2214 	     * Stop at a try conditional not in its finally clause.  If this try
2215 	     * conditional is in an active catch clause, finish the caught
2216 	     * exception.
2217 	     */
2218 	    if (!(cstack->cs_flags[idx] & CSF_FINALLY))
2219 	    {
2220 		if ((cstack->cs_flags[idx] & CSF_ACTIVE)
2221 			&& (cstack->cs_flags[idx] & CSF_CAUGHT))
2222 		    finish_exception((except_T *)cstack->cs_exception[idx]);
2223 		// Stop at this try conditional - except the try block never
2224 		// got active (because of an inactive surrounding conditional
2225 		// or when the ":try" appeared after an error or interrupt or
2226 		// throw).
2227 		if (cstack->cs_flags[idx] & CSF_TRUE)
2228 		{
2229 		    if (searched_cond == 0 && !inclusive)
2230 			break;
2231 		    stop = TRUE;
2232 		}
2233 	    }
2234 	}
2235 
2236 	// Stop on the searched conditional type (even when the surrounding
2237 	// conditional is not active or something has been made pending).
2238 	// If "inclusive" is TRUE and "searched_cond" is CSF_TRY|CSF_SILENT,
2239 	// check first whether "emsg_silent" needs to be restored.
2240 	if (cstack->cs_flags[idx] & searched_cond)
2241 	{
2242 	    if (!inclusive)
2243 		break;
2244 	    stop = TRUE;
2245 	}
2246 	cstack->cs_flags[idx] &= ~CSF_ACTIVE;
2247 	if (stop && searched_cond != (CSF_TRY | CSF_SILENT))
2248 	    break;
2249 
2250 	/*
2251 	 * When leaving a try conditional that reset "emsg_silent" on its
2252 	 * entry after saving the original value, restore that value here and
2253 	 * free the memory used to store it.
2254 	 */
2255 	if ((cstack->cs_flags[idx] & CSF_TRY)
2256 		&& (cstack->cs_flags[idx] & CSF_SILENT))
2257 	{
2258 	    eslist_T	*elem;
2259 
2260 	    elem = cstack->cs_emsg_silent_list;
2261 	    cstack->cs_emsg_silent_list = elem->next;
2262 	    emsg_silent = elem->saved_emsg_silent;
2263 	    vim_free(elem);
2264 	    cstack->cs_flags[idx] &= ~CSF_SILENT;
2265 	}
2266 	if (stop)
2267 	    break;
2268     }
2269     return idx;
2270 }
2271 
2272 /*
2273  * Return an appropriate error message for a missing endwhile/endfor/endif.
2274  */
2275    static char *
2276 get_end_emsg(cstack_T *cstack)
2277 {
2278     if (cstack->cs_flags[cstack->cs_idx] & CSF_WHILE)
2279 	return _(e_endwhile);
2280     if (cstack->cs_flags[cstack->cs_idx] & CSF_FOR)
2281 	return _(e_endfor);
2282     return _(e_endif);
2283 }
2284 
2285 
2286 /*
2287  * Rewind conditionals until index "idx" is reached.  "cond_type" and
2288  * "cond_level" specify a conditional type and the address of a level variable
2289  * which is to be decremented with each skipped conditional of the specified
2290  * type.
2291  * Also free "for info" structures where needed.
2292  */
2293     void
2294 rewind_conditionals(
2295     cstack_T   *cstack,
2296     int		idx,
2297     int		cond_type,
2298     int		*cond_level)
2299 {
2300     while (cstack->cs_idx > idx)
2301     {
2302 	if (cstack->cs_flags[cstack->cs_idx] & cond_type)
2303 	    --*cond_level;
2304 	if (cstack->cs_flags[cstack->cs_idx] & CSF_FOR)
2305 	    free_for_info(cstack->cs_forinfo[cstack->cs_idx]);
2306 	--cstack->cs_idx;
2307     }
2308 }
2309 
2310 /*
2311  * ":endfunction" when not after a ":function"
2312  */
2313     void
2314 ex_endfunction(exarg_T *eap)
2315 {
2316     if (eap->cmdidx == CMD_enddef)
2317 	emsg(_("E193: :enddef not inside a function"));
2318     else
2319 	emsg(_("E193: :endfunction not inside a function"));
2320 }
2321 
2322 /*
2323  * Return TRUE if the string "p" looks like a ":while" or ":for" command.
2324  */
2325     int
2326 has_loop_cmd(char_u *p)
2327 {
2328     int		len;
2329 
2330     // skip modifiers, white space and ':'
2331     for (;;)
2332     {
2333 	while (*p == ' ' || *p == '\t' || *p == ':')
2334 	    ++p;
2335 	len = modifier_len(p);
2336 	if (len == 0)
2337 	    break;
2338 	p += len;
2339     }
2340     if ((p[0] == 'w' && p[1] == 'h')
2341 	    || (p[0] == 'f' && p[1] == 'o' && p[2] == 'r'))
2342 	return TRUE;
2343     return FALSE;
2344 }
2345 
2346 #endif // FEAT_EVAL
2347