eval.c 91.7 KB
Newer Older
Jim Blandy's avatar
Jim Blandy committed
1
/* Evaluator for GNU Emacs Lisp interpreter.
2
   Copyright (C) 1985, 86, 87, 93, 94, 95, 99, 2000, 2001
3
     Free Software Foundation, Inc.
Jim Blandy's avatar
Jim Blandy committed
4 5 6 7 8

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
9
the Free Software Foundation; either version 2, or (at your option)
Jim Blandy's avatar
Jim Blandy committed
10 11 12 13 14 15 16 17 18
any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
19 20
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */
Jim Blandy's avatar
Jim Blandy committed
21 22


23
#include <config.h>
Jim Blandy's avatar
Jim Blandy committed
24
#include "lisp.h"
25
#include "blockinput.h"
Jim Blandy's avatar
Jim Blandy committed
26
#include "commands.h"
Jim Blandy's avatar
Jim Blandy committed
27
#include "keyboard.h"
28
#include "dispextern.h"
Jim Blandy's avatar
Jim Blandy committed
29 30 31 32 33 34
#include <setjmp.h>

/* This definition is duplicated in alloc.c and keyboard.c */
/* Putting it in lisp.h makes cc bomb out! */

struct backtrace
35 36 37 38 39
{
  struct backtrace *next;
  Lisp_Object *function;
  Lisp_Object *args;	/* Points to vector of args. */
  int nargs;		/* Length of vector.
Jim Blandy's avatar
Jim Blandy committed
40 41
			   If nargs is UNEVALLED, args points to slot holding
			   list of unevalled args */
42 43 44 45
  char evalargs;
  /* Nonzero means call value of debugger when done with this operation. */
  char debug_on_exit;
};
Jim Blandy's avatar
Jim Blandy committed
46 47 48

struct backtrace *backtrace_list;

49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
/* This structure helps implement the `catch' and `throw' control
   structure.  A struct catchtag contains all the information needed
   to restore the state of the interpreter after a non-local jump.

   Handlers for error conditions (represented by `struct handler'
   structures) just point to a catch tag to do the cleanup required
   for their jumps.

   catchtag structures are chained together in the C calling stack;
   the `next' member points to the next outer catchtag.

   A call like (throw TAG VAL) searches for a catchtag whose `tag'
   member is TAG, and then unbinds to it.  The `val' member is used to
   hold VAL while the stack is unwound; `val' is returned as the value
   of the catch form.

   All the other members are concerned with restoring the interpreter
   state.  */
67

Jim Blandy's avatar
Jim Blandy committed
68
struct catchtag
69 70 71 72 73 74 75 76 77 78 79 80 81
{
  Lisp_Object tag;
  Lisp_Object val;
  struct catchtag *next;
  struct gcpro *gcpro;
  jmp_buf jmp;
  struct backtrace *backlist;
  struct handler *handlerlist;
  int lisp_eval_depth;
  int pdlcount;
  int poll_suppress_count;
  struct byte_stack *byte_stack;
};
Jim Blandy's avatar
Jim Blandy committed
82 83 84

struct catchtag *catchlist;

85 86 87 88 89
#ifdef DEBUG_GCPRO
/* Count levels of GCPRO to detect failure to UNGCPRO.  */
int gcpro_level;
#endif

Jim Blandy's avatar
Jim Blandy committed
90
Lisp_Object Qautoload, Qmacro, Qexit, Qinteractive, Qcommandp, Qdefun;
Jim Blandy's avatar
Jim Blandy committed
91
Lisp_Object Qinhibit_quit, Vinhibit_quit, Vquit_flag;
Jim Blandy's avatar
Jim Blandy committed
92 93 94 95
Lisp_Object Qmocklisp_arguments, Vmocklisp_arguments, Qmocklisp;
Lisp_Object Qand_rest, Qand_optional;
Lisp_Object Qdebug_on_error;

96 97 98
/* This holds either the symbol `run-hooks' or nil.
   It is nil at an early stage of startup, and when Emacs
   is shutting down.  */
99

Jim Blandy's avatar
Jim Blandy committed
100 101 102 103 104 105 106 107 108 109
Lisp_Object Vrun_hooks;

/* Non-nil means record all fset's and provide's, to be undone
   if the file being autoloaded is not fully loaded.
   They are recorded by being consed onto the front of Vautoload_queue:
   (FUN . ODEF) for a defun, (OFEATURES . nil) for a provide.  */

Lisp_Object Vautoload_queue;

/* Current number of specbindings allocated in specpdl.  */
110

Jim Blandy's avatar
Jim Blandy committed
111 112 113
int specpdl_size;

/* Pointer to beginning of specpdl.  */
114

Jim Blandy's avatar
Jim Blandy committed
115 116 117
struct specbinding *specpdl;

/* Pointer to first unused element in specpdl.  */
118

Jim Blandy's avatar
Jim Blandy committed
119 120 121
struct specbinding *specpdl_ptr;

/* Maximum size allowed for specpdl allocation */
122

Jim Blandy's avatar
Jim Blandy committed
123 124 125
int max_specpdl_size;

/* Depth in Lisp evaluations and function calls.  */
126

Jim Blandy's avatar
Jim Blandy committed
127 128 129
int lisp_eval_depth;

/* Maximum allowed depth in Lisp evaluations and function calls.  */
130

Jim Blandy's avatar
Jim Blandy committed
131 132 133
int max_lisp_eval_depth;

/* Nonzero means enter debugger before next function call */
134

Jim Blandy's avatar
Jim Blandy committed
135 136
int debug_on_next_call;

137
/* Non-zero means debugger may continue.  This is zero when the
138 139 140 141 142
   debugger is called during redisplay, where it might not be safe to
   continue the interrupted redisplay. */

int debugger_may_continue;

Roland McGrath's avatar
Roland McGrath committed
143
/* List of conditions (non-nil atom means all) which cause a backtrace
144
   if an error is handled by the command loop's error handler.  */
145

Roland McGrath's avatar
Roland McGrath committed
146
Lisp_Object Vstack_trace_on_error;
Jim Blandy's avatar
Jim Blandy committed
147

Roland McGrath's avatar
Roland McGrath committed
148
/* List of conditions (non-nil atom means all) which enter the debugger
149
   if an error is handled by the command loop's error handler.  */
150

Roland McGrath's avatar
Roland McGrath committed
151
Lisp_Object Vdebug_on_error;
Jim Blandy's avatar
Jim Blandy committed
152

Karl Heuer's avatar
Karl Heuer committed
153
/* List of conditions and regexps specifying error messages which
154
   do not enter the debugger even if Vdebug_on_error says they should.  */
155

Karl Heuer's avatar
Karl Heuer committed
156 157
Lisp_Object Vdebug_ignored_errors;

158
/* Non-nil means call the debugger even if the error will be handled.  */
159

160
Lisp_Object Vdebug_on_signal;
161 162

/* Hook for edebug to use.  */
163

164 165
Lisp_Object Vsignal_hook_function;

Jim Blandy's avatar
Jim Blandy committed
166
/* Nonzero means enter debugger if a quit signal
Roland McGrath's avatar
Roland McGrath committed
167
   is handled by the command loop's error handler. */
168

Jim Blandy's avatar
Jim Blandy committed
169 170
int debug_on_quit;

171
/* The value of num_nonmacro_input_events as of the last time we
172
   started to enter the debugger.  If we decide to enter the debugger
173
   again when this is still equal to num_nonmacro_input_events, then we
174 175 176
   know that the debugger itself has an error, and we should just
   signal the error instead of entering an infinite loop of debugger
   invocations.  */
177

178
int when_entered_debugger;
Jim Blandy's avatar
Jim Blandy committed
179 180 181

Lisp_Object Vdebugger;

182 183 184 185 186
/* The function from which the last `signal' was called.  Set in
   Fsignal.  */

Lisp_Object Vsignaling_function;

187 188 189 190 191 192
/* Set to non-zero while processing X events.  Checked in Feval to
   make sure the Lisp interpreter isn't called from a signal handler,
   which is unsafe because the interpreter isn't reentrant.  */

int handling_signal;

Jim Blandy's avatar
Jim Blandy committed
193 194
void specbind (), record_unwind_protect ();

195 196
Lisp_Object run_hook_with_args ();

Jim Blandy's avatar
Jim Blandy committed
197 198 199
Lisp_Object funcall_lambda ();
extern Lisp_Object ml_apply (); /* Apply a mocklisp function to unevaluated argument list */

Andreas Schwab's avatar
Andreas Schwab committed
200
void
Jim Blandy's avatar
Jim Blandy committed
201 202 203
init_eval_once ()
{
  specpdl_size = 50;
204
  specpdl = (struct specbinding *) xmalloc (specpdl_size * sizeof (struct specbinding));
205
  specpdl_ptr = specpdl;
Jim Blandy's avatar
Jim Blandy committed
206
  max_specpdl_size = 600;
207
  max_lisp_eval_depth = 300;
208 209

  Vrun_hooks = Qnil;
Jim Blandy's avatar
Jim Blandy committed
210 211
}

Andreas Schwab's avatar
Andreas Schwab committed
212
void
Jim Blandy's avatar
Jim Blandy committed
213 214 215 216 217 218 219 220 221
init_eval ()
{
  specpdl_ptr = specpdl;
  catchlist = 0;
  handlerlist = 0;
  backtrace_list = 0;
  Vquit_flag = Qnil;
  debug_on_next_call = 0;
  lisp_eval_depth = 0;
222
#ifdef DEBUG_GCPRO
223
  gcpro_level = 0;
224
#endif
225
  /* This is less than the initial value of num_nonmacro_input_events.  */
226
  when_entered_debugger = -1;
Jim Blandy's avatar
Jim Blandy committed
227 228 229 230 231 232
}

Lisp_Object
call_debugger (arg)
     Lisp_Object arg;
{
233
  int debug_while_redisplaying;
234
  int count = specpdl_ptr - specpdl;
235 236
  Lisp_Object val;
  
Jim Blandy's avatar
Jim Blandy committed
237 238
  if (lisp_eval_depth + 20 > max_lisp_eval_depth)
    max_lisp_eval_depth = lisp_eval_depth + 20;
239
  
Jim Blandy's avatar
Jim Blandy committed
240 241
  if (specpdl_size + 40 > max_specpdl_size)
    max_specpdl_size = specpdl_size + 40;
242
  
243
#ifdef HAVE_X_WINDOWS
244 245
  if (display_hourglass_p)
    cancel_hourglass ();
246 247
#endif

Jim Blandy's avatar
Jim Blandy committed
248
  debug_on_next_call = 0;
249
  when_entered_debugger = num_nonmacro_input_events;
250 251 252 253 254

  /* Resetting redisplaying_p to 0 makes sure that debug output is
     displayed if the debugger is invoked during redisplay.  */
  debug_while_redisplaying = redisplaying_p;
  redisplaying_p = 0;
255 256
  specbind (intern ("debugger-may-continue"),
	    debug_while_redisplaying ? Qnil : Qt);
257
  specbind (Qinhibit_redisplay, Qnil);
258 259 260

#if 0 /* Binding this prevents execution of Lisp code during
	 redisplay, which necessarily leads to display problems.  */
261
  specbind (Qinhibit_eval_during_redisplay, Qt);
262
#endif
263 264 265 266 267
  
  val = apply1 (Vdebugger, arg);

  /* Interrupting redisplay and resuming it later is not safe under
     all circumstances.  So, when the debugger returns, abort the
268
     interrupted redisplay by going back to the top-level.  */
269 270 271
  if (debug_while_redisplaying)
    Ftop_level ();

272
  return unbind_to (count, val);
Jim Blandy's avatar
Jim Blandy committed
273 274
}

Andreas Schwab's avatar
Andreas Schwab committed
275
void
Jim Blandy's avatar
Jim Blandy committed
276 277 278 279 280 281 282 283 284 285 286 287 288
do_debug_on_call (code)
     Lisp_Object code;
{
  debug_on_next_call = 0;
  backtrace_list->debug_on_exit = 1;
  call_debugger (Fcons (code, Qnil));
}

/* NOTE!!! Every function that can call EVAL must protect its args
   and temporaries from garbage collection while it needs them.
   The definition of `For' shows what you have to do.  */

DEFUN ("or", For, Sor, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
289 290 291 292 293
       doc: /* Eval args until one of them yields non-nil, then return that value.
The remaining args are not evalled at all.
If all args return nil, return nil.
usage: (or CONDITIONS ...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
294 295 296 297 298 299
     Lisp_Object args;
{
  register Lisp_Object val;
  Lisp_Object args_left;
  struct gcpro gcpro1;

Jim Blandy's avatar
Jim Blandy committed
300
  if (NILP(args))
Jim Blandy's avatar
Jim Blandy committed
301 302 303 304 305 306 307 308
    return Qnil;

  args_left = args;
  GCPRO1 (args_left);

  do
    {
      val = Feval (Fcar (args_left));
Jim Blandy's avatar
Jim Blandy committed
309
      if (!NILP (val))
Jim Blandy's avatar
Jim Blandy committed
310 311 312
	break;
      args_left = Fcdr (args_left);
    }
Jim Blandy's avatar
Jim Blandy committed
313
  while (!NILP(args_left));
Jim Blandy's avatar
Jim Blandy committed
314 315 316 317 318 319

  UNGCPRO;
  return val;
}

DEFUN ("and", Fand, Sand, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
320 321 322 323 324
  doc: /* Eval args until one of them yields nil, then return nil.
The remaining args are not evalled at all.
If no arg yields nil, return the last arg's value.
usage: (and CONDITIONS ...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
325 326 327 328 329 330
     Lisp_Object args;
{
  register Lisp_Object val;
  Lisp_Object args_left;
  struct gcpro gcpro1;

Jim Blandy's avatar
Jim Blandy committed
331
  if (NILP(args))
Jim Blandy's avatar
Jim Blandy committed
332 333 334 335 336 337 338 339
    return Qt;

  args_left = args;
  GCPRO1 (args_left);

  do
    {
      val = Feval (Fcar (args_left));
Jim Blandy's avatar
Jim Blandy committed
340
      if (NILP (val))
Jim Blandy's avatar
Jim Blandy committed
341 342 343
	break;
      args_left = Fcdr (args_left);
    }
Jim Blandy's avatar
Jim Blandy committed
344
  while (!NILP(args_left));
Jim Blandy's avatar
Jim Blandy committed
345 346 347 348 349 350

  UNGCPRO;
  return val;
}

DEFUN ("if", Fif, Sif, 2, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
351 352 353 354 355 356
  doc: /* If COND yields non-nil, do THEN, else do ELSE...
Returns the value of THEN or the value of the last of the ELSE's.
THEN must be one expression, but ELSE... can be zero or more expressions.
If COND yields nil, and there are no ELSE's, the value is nil.
usage: (if COND THEN ELSE...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
357 358 359 360 361 362 363 364 365
     Lisp_Object args;
{
  register Lisp_Object cond;
  struct gcpro gcpro1;

  GCPRO1 (args);
  cond = Feval (Fcar (args));
  UNGCPRO;

Jim Blandy's avatar
Jim Blandy committed
366
  if (!NILP (cond))
Jim Blandy's avatar
Jim Blandy committed
367 368 369 370 371
    return Feval (Fcar (Fcdr (args)));
  return Fprogn (Fcdr (Fcdr (args)));
}

DEFUN ("cond", Fcond, Scond, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
372 373 374 375 376 377 378 379 380 381
       doc: /* Try each clause until one succeeds.
Each clause looks like (CONDITION BODY...).  CONDITION is evaluated
and, if the value is non-nil, this clause succeeds:
then the expressions in BODY are evaluated and the last one's
value is the value of the cond-form.
If no clause succeeds, cond returns nil.
If a clause has one element, as in (CONDITION),
CONDITION's value if non-nil is returned from the cond-form.
usage: (cond CLAUSES...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
382 383 384 385 386 387 388
     Lisp_Object args;
{
  register Lisp_Object clause, val;
  struct gcpro gcpro1;

  val = Qnil;
  GCPRO1 (args);
Jim Blandy's avatar
Jim Blandy committed
389
  while (!NILP (args))
Jim Blandy's avatar
Jim Blandy committed
390 391 392
    {
      clause = Fcar (args);
      val = Feval (Fcar (clause));
Jim Blandy's avatar
Jim Blandy committed
393
      if (!NILP (val))
Jim Blandy's avatar
Jim Blandy committed
394
	{
395 396
	  if (!EQ (XCDR (clause), Qnil))
	    val = Fprogn (XCDR (clause));
Jim Blandy's avatar
Jim Blandy committed
397 398
	  break;
	}
399
      args = XCDR (args);
Jim Blandy's avatar
Jim Blandy committed
400 401 402 403 404 405 406
    }
  UNGCPRO;

  return val;
}

DEFUN ("progn", Fprogn, Sprogn, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
407 408 409
       doc: /* Eval BODY forms sequentially and return value of last one.
usage: (progn BODY ...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
410 411 412 413 414 415 416 417 418 419 420
     Lisp_Object args;
{
  register Lisp_Object val, tem;
  Lisp_Object args_left;
  struct gcpro gcpro1;

  /* In Mocklisp code, symbols at the front of the progn arglist
   are to be bound to zero. */
  if (!EQ (Vmocklisp_arguments, Qt))
    {
      val = make_number (0);
421
      while (!NILP (args) && (tem = Fcar (args), SYMBOLP (tem)))
Jim Blandy's avatar
Jim Blandy committed
422 423 424 425 426 427
	{
	  QUIT;
	  specbind (tem, val), args = Fcdr (args);
	}
    }

Jim Blandy's avatar
Jim Blandy committed
428
  if (NILP(args))
Jim Blandy's avatar
Jim Blandy committed
429 430 431 432 433 434 435 436 437 438
    return Qnil;

  args_left = args;
  GCPRO1 (args_left);

  do
    {
      val = Feval (Fcar (args_left));
      args_left = Fcdr (args_left);
    }
Jim Blandy's avatar
Jim Blandy committed
439
  while (!NILP(args_left));
Jim Blandy's avatar
Jim Blandy committed
440 441 442 443 444 445

  UNGCPRO;
  return val;
}

DEFUN ("prog1", Fprog1, Sprog1, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
446 447 448 449 450
       doc: /* Eval FIRST and BODY sequentially; value from FIRST.
The value of FIRST is saved during the evaluation of the remaining args,
whose values are discarded.
usage: (prog1 FIRST BODY...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
451 452 453 454 455 456 457
     Lisp_Object args;
{
  Lisp_Object val;
  register Lisp_Object args_left;
  struct gcpro gcpro1, gcpro2;
  register int argnum = 0;

Jim Blandy's avatar
Jim Blandy committed
458
  if (NILP(args))
Jim Blandy's avatar
Jim Blandy committed
459 460 461 462 463 464 465 466 467 468 469 470 471 472
    return Qnil;

  args_left = args;
  val = Qnil;
  GCPRO2 (args, val);

  do
    {
      if (!(argnum++))
        val = Feval (Fcar (args_left));
      else
	Feval (Fcar (args_left));
      args_left = Fcdr (args_left);
    }
Jim Blandy's avatar
Jim Blandy committed
473
  while (!NILP(args_left));
Jim Blandy's avatar
Jim Blandy committed
474 475 476 477 478 479

  UNGCPRO;
  return val;
}

DEFUN ("prog2", Fprog2, Sprog2, 2, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
480 481 482 483 484
       doc: /* Eval X, Y and BODY sequentially; value from Y.
The value of Y is saved during the evaluation of the remaining args,
whose values are discarded.
usage: (prog2 X Y BODY...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
485 486 487 488 489 490 491 492 493
     Lisp_Object args;
{
  Lisp_Object val;
  register Lisp_Object args_left;
  struct gcpro gcpro1, gcpro2;
  register int argnum = -1;

  val = Qnil;

Richard M. Stallman's avatar
Richard M. Stallman committed
494
  if (NILP (args))
Jim Blandy's avatar
Jim Blandy committed
495 496 497 498 499 500 501 502 503 504 505 506 507 508
    return Qnil;

  args_left = args;
  val = Qnil;
  GCPRO2 (args, val);

  do
    {
      if (!(argnum++))
        val = Feval (Fcar (args_left));
      else
	Feval (Fcar (args_left));
      args_left = Fcdr (args_left);
    }
Richard M. Stallman's avatar
Richard M. Stallman committed
509
  while (!NILP (args_left));
Jim Blandy's avatar
Jim Blandy committed
510 511 512 513 514 515

  UNGCPRO;
  return val;
}

DEFUN ("setq", Fsetq, Ssetq, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
516 517 518 519 520 521 522 523 524
       doc: /* Set each SYM to the value of its VAL.
The symbols SYM are variables; they are literal (not evaluated).
The values VAL are expressions; they are evaluated.
Thus, (setq x (1+ y)) sets `x' to the value of `(1+ y)'.
The second VAL is not computed until after the first SYM is set, and so on;
each VAL can use the new value of variables set earlier in the `setq'.
The return value of the `setq' form is the value of the last VAL.
usage: (setq SYM VAL SYM VAL ...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
525 526 527 528 529 530
     Lisp_Object args;
{
  register Lisp_Object args_left;
  register Lisp_Object val, sym;
  struct gcpro gcpro1;

Jim Blandy's avatar
Jim Blandy committed
531
  if (NILP(args))
Jim Blandy's avatar
Jim Blandy committed
532 533 534 535 536 537 538 539 540 541 542 543
    return Qnil;

  args_left = args;
  GCPRO1 (args);

  do
    {
      val = Feval (Fcar (Fcdr (args_left)));
      sym = Fcar (args_left);
      Fset (sym, val);
      args_left = Fcdr (Fcdr (args_left));
    }
Jim Blandy's avatar
Jim Blandy committed
544
  while (!NILP(args_left));
Jim Blandy's avatar
Jim Blandy committed
545 546 547 548 549 550

  UNGCPRO;
  return val;
}
     
DEFUN ("quote", Fquote, Squote, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
551 552 553
       doc: /* Return the argument, without evaluating it.  `(quote x)' yields `x'.
usage: (quote ARG)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
554 555 556 557 558 559
     Lisp_Object args;
{
  return Fcar (args);
}
     
DEFUN ("function", Ffunction, Sfunction, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
560 561 562 563 564
       doc: /* Like `quote', but preferred for objects which are functions.
In byte compilation, `function' causes its argument to be compiled.
`quote' cannot do that.
usage: (function ARG)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
565 566 567 568 569
     Lisp_Object args;
{
  return Fcar (args);
}

570

Jim Blandy's avatar
Jim Blandy committed
571
DEFUN ("interactive-p", Finteractive_p, Sinteractive_p, 0, 0, 0,
Pavel Janík's avatar
Pavel Janík committed
572 573 574 575 576
       doc: /* Return t if function in which this appears was called interactively.
This means that the function was called with call-interactively (which
includes being called as the binding of a key)
and input is currently coming from the keyboard (not in keyboard macro).  */)
     ()
Jim Blandy's avatar
Jim Blandy committed
577
{
578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596
  return interactive_p (1) ? Qt : Qnil;
}


/*  Return 1 if function in which this appears was called
    interactively.  This means that the function was called with
    call-interactively (which includes being called as the binding of
    a key) and input is currently coming from the keyboard (not in
    keyboard macro).

    EXCLUDE_SUBRS_P non-zero means always return 0 if the function
    called is a built-in.  */

int
interactive_p (exclude_subrs_p)
     int exclude_subrs_p;
{
  struct backtrace *btp;
  Lisp_Object fun;
Jim Blandy's avatar
Jim Blandy committed
597 598

  if (!INTERACTIVE)
599
    return 0;
Jim Blandy's avatar
Jim Blandy committed
600 601

  btp = backtrace_list;
Jim Blandy's avatar
Jim Blandy committed
602 603

  /* If this isn't a byte-compiled function, there may be a frame at
604
     the top for Finteractive_p.  If so, skip it.  */
Jim Blandy's avatar
Jim Blandy committed
605
  fun = Findirect_function (*btp->function);
606
  if (SUBRP (fun) && XSUBR (fun) == &Sinteractive_p)
Jim Blandy's avatar
Jim Blandy committed
607
    btp = btp->next;
Jim Blandy's avatar
Jim Blandy committed
608 609 610 611 612 613 614 615 616 617 618 619 620

  /* If we're running an Emacs 18-style byte-compiled function, there
     may be a frame for Fbytecode.  Now, given the strictest
     definition, this function isn't really being called
     interactively, but because that's the way Emacs 18 always builds
     byte-compiled functions, we'll accept it for now.  */
  if (EQ (*btp->function, Qbytecode))
    btp = btp->next;

  /* If this isn't a byte-compiled function, then we may now be
     looking at several frames for special forms.  Skip past them.  */
  while (btp && 
	 btp->nargs == UNEVALLED)
Jim Blandy's avatar
Jim Blandy committed
621 622
    btp = btp->next;

Jim Blandy's avatar
Jim Blandy committed
623 624 625 626
  /* btp now points at the frame of the innermost function that isn't
     a special form, ignoring frames for Finteractive_p and/or
     Fbytecode at the top.  If this frame is for a built-in function
     (such as load or eval-region) return nil.  */
Jim Blandy's avatar
Jim Blandy committed
627
  fun = Findirect_function (*btp->function);
628 629 630
  if (exclude_subrs_p && SUBRP (fun))
    return 0;
  
Jim Blandy's avatar
Jim Blandy committed
631 632 633
  /* btp points to the frame of a Lisp function that called interactive-p.
     Return t if that function was called interactively.  */
  if (btp && btp->next && EQ (*btp->next->function, Qcall_interactively))
634 635
    return 1;
  return 0;
Jim Blandy's avatar
Jim Blandy committed
636 637
}

638

Jim Blandy's avatar
Jim Blandy committed
639
DEFUN ("defun", Fdefun, Sdefun, 2, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
640 641 642 643 644
       doc: /* Define NAME as a function.
The definition is (lambda ARGLIST [DOCSTRING] BODY...).
See also the function `interactive'.
usage: (defun NAME ARGLIST [DOCSTRING] BODY...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
645 646 647 648 649 650 651
     Lisp_Object args;
{
  register Lisp_Object fn_name;
  register Lisp_Object defn;

  fn_name = Fcar (args);
  defn = Fcons (Qlambda, Fcdr (args));
Jim Blandy's avatar
Jim Blandy committed
652
  if (!NILP (Vpurify_flag))
Jim Blandy's avatar
Jim Blandy committed
653 654
    defn = Fpurecopy (defn);
  Ffset (fn_name, defn);
655
  LOADHIST_ATTACH (fn_name);
Jim Blandy's avatar
Jim Blandy committed
656 657 658 659
  return fn_name;
}

DEFUN ("defmacro", Fdefmacro, Sdefmacro, 2, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
660 661 662 663 664 665 666 667
       doc: /* Define NAME as a macro.
The definition is (macro lambda ARGLIST [DOCSTRING] BODY...).
When the macro is called, as in (NAME ARGS...),
the function (lambda ARGLIST BODY...) is applied to
the list ARGS... as it appears in the expression,
and the result should be a form to be evaluated instead of the original.
usage: (defmacro NAME ARGLIST [DOCSTRING] BODY...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
668 669 670 671 672 673 674
     Lisp_Object args;
{
  register Lisp_Object fn_name;
  register Lisp_Object defn;

  fn_name = Fcar (args);
  defn = Fcons (Qmacro, Fcons (Qlambda, Fcdr (args)));
Jim Blandy's avatar
Jim Blandy committed
675
  if (!NILP (Vpurify_flag))
Jim Blandy's avatar
Jim Blandy committed
676 677
    defn = Fpurecopy (defn);
  Ffset (fn_name, defn);
678
  LOADHIST_ATTACH (fn_name);
Jim Blandy's avatar
Jim Blandy committed
679 680 681
  return fn_name;
}

Gerd Moellmann's avatar
Gerd Moellmann committed
682 683

DEFUN ("defvaralias", Fdefvaralias, Sdefvaralias, 2, 2, 0,
Pavel Janík's avatar
Pavel Janík committed
684 685 686 687 688
       doc: /* Make SYMBOL a variable alias for symbol ALIASED.
Setting the value of SYMBOL will subsequently set the value of ALIASED,
and getting the value of SYMBOL will return the value ALIASED has.
ALIASED nil means remove the alias; SYMBOL is unbound after that.  */)
     (symbol, aliased)
Gerd Moellmann's avatar
Gerd Moellmann committed
689 690 691 692
     Lisp_Object symbol, aliased;
{
  struct Lisp_Symbol *sym;
  
693 694
  CHECK_SYMBOL (symbol);
  CHECK_SYMBOL (aliased);
Gerd Moellmann's avatar
Gerd Moellmann committed
695 696 697 698 699 700 701 702 703 704 705 706 707 708

  if (SYMBOL_CONSTANT_P (symbol))
    error ("Cannot make a constant an alias");

  sym = XSYMBOL (symbol);
  sym->indirect_variable = 1;
  sym->value = aliased;
  sym->constant = SYMBOL_CONSTANT_P (aliased);
  LOADHIST_ATTACH (symbol);
  
  return aliased;
}


Jim Blandy's avatar
Jim Blandy committed
709
DEFUN ("defvar", Fdefvar, Sdefvar, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
710 711 712 713 714 715 716 717 718 719 720 721 722
       doc: /* Define SYMBOL as a variable.
You are not required to define a variable in order to use it,
but the definition can supply documentation and an initial value
in a way that tags can recognize.

INITVALUE is evaluated, and used to set SYMBOL, only if SYMBOL's value is void.
If SYMBOL is buffer-local, its default value is what is set;
 buffer-local values are not affected.
INITVALUE and DOCSTRING are optional.
If DOCSTRING starts with *, this variable is identified as a user option.
 This means that M-x set-variable recognizes it.
 See also `user-variable-p'.
If INITVALUE is missing, SYMBOL's value is not set.
723
usage: (defvar SYMBOL &optional INITVALUE DOCSTRING)  */)
Pavel Janík's avatar
Pavel Janík committed
724
     (args)
Jim Blandy's avatar
Jim Blandy committed
725 726
     Lisp_Object args;
{
727
  register Lisp_Object sym, tem, tail;
Jim Blandy's avatar
Jim Blandy committed
728 729

  sym = Fcar (args);
730 731 732 733
  tail = Fcdr (args);
  if (!NILP (Fcdr (Fcdr (tail))))
    error ("too many arguments");

734
  tem = Fdefault_boundp (sym);
735
  if (!NILP (tail))
Jim Blandy's avatar
Jim Blandy committed
736
    {
Jim Blandy's avatar
Jim Blandy committed
737
      if (NILP (tem))
738 739 740 741 742 743 744 745 746 747
	Fset_default (sym, Feval (Fcar (tail)));
      tail = Fcdr (tail);
      if (!NILP (Fcar (tail)))
	{
	  tem = Fcar (tail);
	  if (!NILP (Vpurify_flag))
	    tem = Fpurecopy (tem);
	  Fput (sym, Qvariable_documentation, tem);
	}
      LOADHIST_ATTACH (sym);
Jim Blandy's avatar
Jim Blandy committed
748
    }
749 750 751 752 753 754 755
  else
    /* A (defvar <var>) should not take precedence in the load-history over
       an earlier (defvar <var> <val>), so only add to history if the default
       value is still unbound.  */
    if (NILP (tem))
      LOADHIST_ATTACH (sym);
    
Jim Blandy's avatar
Jim Blandy committed
756 757 758 759
  return sym;
}

DEFUN ("defconst", Fdefconst, Sdefconst, 2, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
760 761 762 763 764 765 766 767
       doc: /* Define SYMBOL as a constant variable.
The intent is that neither programs nor users should ever change this value.
Always sets the value of SYMBOL to the result of evalling INITVALUE.
If SYMBOL is buffer-local, its default value is what is set;
 buffer-local values are not affected.
DOCSTRING is optional.
usage: (defconst SYMBOL INITVALUE [DOCSTRING])  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
768 769 770 771 772
     Lisp_Object args;
{
  register Lisp_Object sym, tem;

  sym = Fcar (args);
773 774 775
  if (!NILP (Fcdr (Fcdr (Fcdr (args)))))
    error ("too many arguments");

776 777 778 779
  tem = Feval (Fcar (Fcdr (args)));
  if (!NILP (Vpurify_flag))
    tem = Fpurecopy (tem);
  Fset_default (sym, tem);
Jim Blandy's avatar
Jim Blandy committed
780
  tem = Fcar (Fcdr (Fcdr (args)));
Jim Blandy's avatar
Jim Blandy committed
781
  if (!NILP (tem))
Jim Blandy's avatar
Jim Blandy committed
782
    {
Jim Blandy's avatar
Jim Blandy committed
783
      if (!NILP (Vpurify_flag))
Jim Blandy's avatar
Jim Blandy committed
784 785 786
	tem = Fpurecopy (tem);
      Fput (sym, Qvariable_documentation, tem);
    }
787
  LOADHIST_ATTACH (sym);
Jim Blandy's avatar
Jim Blandy committed
788 789 790 791
  return sym;
}

DEFUN ("user-variable-p", Fuser_variable_p, Suser_variable_p, 1, 1, 0,
Pavel Janík's avatar
Pavel Janík committed
792 793 794 795 796 797 798
       doc: /* Returns t if VARIABLE is intended to be set and modified by users.
\(The alternative is a variable used internally in a Lisp program.)
Determined by whether the first character of the documentation
for the variable is `*' or if the variable is customizable (has a non-nil
value of any of `custom-type', `custom-loads' or `standard-value'
on its property list).  */)
     (variable)
Jim Blandy's avatar
Jim Blandy committed
799 800 801 802
     Lisp_Object variable;
{
  Lisp_Object documentation;
  
803 804 805
  if (!SYMBOLP (variable))
      return Qnil;

Jim Blandy's avatar
Jim Blandy committed
806
  documentation = Fget (variable, Qvariable_documentation);
807
  if (INTEGERP (documentation) && XINT (documentation) < 0)
Jim Blandy's avatar
Jim Blandy committed
808
    return Qt;
809 810 811 812 813
  if (STRINGP (documentation)
      && ((unsigned char) XSTRING (documentation)->data[0] == '*'))
    return Qt;
  /* If it is (STRING . INTEGER), a negative integer means a user variable.  */
  if (CONSP (documentation)
814 815 816
      && STRINGP (XCAR (documentation))
      && INTEGERP (XCDR (documentation))
      && XINT (XCDR (documentation)) < 0)
Jim Blandy's avatar
Jim Blandy committed
817
    return Qt;
818 819 820 821 822
  /* Customizable?  */
  if ((!NILP (Fget (variable, intern ("custom-type"))))
      || (!NILP (Fget (variable, intern ("custom-loads"))))
      || (!NILP (Fget (variable, intern ("standard-value")))))
    return Qt;
Jim Blandy's avatar
Jim Blandy committed
823 824 825 826
  return Qnil;
}  

DEFUN ("let*", FletX, SletX, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
827 828 829 830 831 832 833
       doc: /* Bind variables according to VARLIST then eval BODY.
The value of the last form in BODY is returned.
Each element of VARLIST is a symbol (which is bound to nil)
or a list (SYMBOL VALUEFORM) (which binds SYMBOL to the value of VALUEFORM).
Each VALUEFORM can refer to the symbols already bound by this VARLIST.
usage: (let* VARLIST BODY...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
834 835 836 837 838 839 840 841 842
     Lisp_Object args;
{
  Lisp_Object varlist, val, elt;
  int count = specpdl_ptr - specpdl;
  struct gcpro gcpro1, gcpro2, gcpro3;

  GCPRO3 (args, elt, varlist);

  varlist = Fcar (args);
Jim Blandy's avatar
Jim Blandy committed
843
  while (!NILP (varlist))
Jim Blandy's avatar
Jim Blandy committed
844 845 846
    {
      QUIT;
      elt = Fcar (varlist);
847
      if (SYMBOLP (elt))
Jim Blandy's avatar
Jim Blandy committed
848
	specbind (elt, Qnil);
Jim Blandy's avatar
Jim Blandy committed
849 850 851 852
      else if (! NILP (Fcdr (Fcdr (elt))))
	Fsignal (Qerror,
		 Fcons (build_string ("`let' bindings can have only one value-form"),
			elt));
Jim Blandy's avatar
Jim Blandy committed
853 854 855 856 857 858 859 860 861 862 863 864 865
      else
	{
	  val = Feval (Fcar (Fcdr (elt)));
	  specbind (Fcar (elt), val);
	}
      varlist = Fcdr (varlist);
    }
  UNGCPRO;
  val = Fprogn (Fcdr (args));
  return unbind_to (count, val);
}

DEFUN ("let", Flet, Slet, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
866 867 868 869 870 871 872
       doc: /* Bind variables according to VARLIST then eval BODY.
The value of the last form in BODY is returned.
Each element of VARLIST is a symbol (which is bound to nil)
or a list (SYMBOL VALUEFORM) (which binds SYMBOL to the value of VALUEFORM).
All the VALUEFORMs are evalled before any symbols are bound.
usage: (let VARLIST BODY...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891
     Lisp_Object args;
{
  Lisp_Object *temps, tem;
  register Lisp_Object elt, varlist;
  int count = specpdl_ptr - specpdl;
  register int argnum;
  struct gcpro gcpro1, gcpro2;

  varlist = Fcar (args);

  /* Make space to hold the values to give the bound variables */
  elt = Flength (varlist);
  temps = (Lisp_Object *) alloca (XFASTINT (elt) * sizeof (Lisp_Object));

  /* Compute the values and store them in `temps' */

  GCPRO2 (args, *temps);
  gcpro2.nvars = 0;

Jim Blandy's avatar
Jim Blandy committed
892
  for (argnum = 0; !NILP (varlist); varlist = Fcdr (varlist))
Jim Blandy's avatar
Jim Blandy committed
893 894 895
    {
      QUIT;
      elt = Fcar (varlist);
896
      if (SYMBOLP (elt))
Jim Blandy's avatar
Jim Blandy committed
897
	temps [argnum++] = Qnil;
Jim Blandy's avatar
Jim Blandy committed
898 899 900 901
      else if (! NILP (Fcdr (Fcdr (elt))))
	Fsignal (Qerror,
		 Fcons (build_string ("`let' bindings can have only one value-form"),
			elt));
Jim Blandy's avatar
Jim Blandy committed
902 903 904 905 906 907 908
      else
	temps [argnum++] = Feval (Fcar (Fcdr (elt)));
      gcpro2.nvars = argnum;
    }
  UNGCPRO;

  varlist = Fcar (args);
Jim Blandy's avatar
Jim Blandy committed
909
  for (argnum = 0; !NILP (varlist); varlist = Fcdr (varlist))
Jim Blandy's avatar
Jim Blandy committed
910 911 912
    {
      elt = Fcar (varlist);
      tem = temps[argnum++];
913
      if (SYMBOLP (elt))
Jim Blandy's avatar
Jim Blandy committed
914 915 916 917 918 919 920 921 922 923
	specbind (elt, tem);
      else
	specbind (Fcar (elt), tem);
    }

  elt = Fprogn (Fcdr (args));
  return unbind_to (count, elt);
}

DEFUN ("while", Fwhile, Swhile, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
924 925 926 927 928
       doc: /* If TEST yields non-nil, eval BODY... and repeat.
The order of execution is thus TEST, BODY, TEST, BODY and so on
until TEST returns nil.
usage: (while TEST BODY...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
929 930 931 932 933 934 935 936 937
     Lisp_Object args;
{
  Lisp_Object test, body, tem;
  struct gcpro gcpro1, gcpro2;

  GCPRO2 (test, body);

  test = Fcar (args);
  body = Fcdr (args);
938 939
  while (tem = Feval (test),
	 (!EQ (Vmocklisp_arguments, Qt) ? XINT (tem) : !NILP (tem)))
Jim Blandy's avatar
Jim Blandy committed
940 941 942 943 944 945 946 947 948 949
    {
      QUIT;
      Fprogn (body);
    }

  UNGCPRO;
  return Qnil;
}

DEFUN ("macroexpand", Fmacroexpand, Smacroexpand, 1, 2, 0,
Pavel Janík's avatar
Pavel Janík committed
950 951 952 953 954 955 956 957
       doc: /* Return result of expanding macros at top level of FORM.
If FORM is not a macro call, it is returned unchanged.
Otherwise, the macro is expanded and the expansion is considered
in place of FORM.  When a non-macro-call results, it is returned.

The second optional arg ENVIRONMENT specifies an environment of macro
definitions to shadow the loaded ones for use in file byte-compilation.  */)
     (form, environment)
958
     Lisp_Object form;
959
     Lisp_Object environment;
Jim Blandy's avatar
Jim Blandy committed
960
{
Jim Blandy's avatar
Jim Blandy committed
961
  /* With cleanups from Hallvard Furuseth.  */
Jim Blandy's avatar
Jim Blandy committed
962 963 964 965 966 967
  register Lisp_Object expander, sym, def, tem;

  while (1)
    {
      /* Come back here each time we expand a macro call,
	 in case it expands into another macro call.  */
968
      if (!CONSP (form))
Jim Blandy's avatar
Jim Blandy committed
969
	break;
Jim Blandy's avatar
Jim Blandy committed
970
      /* Set SYM, give DEF and TEM right values in case SYM is not a symbol. */
971
      def = sym = XCAR (form);
Jim Blandy's avatar
Jim Blandy committed
972
      tem = Qnil;
Jim Blandy's avatar
Jim Blandy committed
973 974
      /* Trace symbols aliases to other symbols
	 until we get a symbol that is not an alias.  */
975
      while (SYMBOLP (def))
Jim Blandy's avatar
Jim Blandy committed
976 977
	{
	  QUIT;
Jim Blandy's avatar
Jim Blandy committed
978
	  sym = def;
979
	  tem = Fassq (sym, environment);
Jim Blandy's avatar
Jim Blandy committed
980
	  if (NILP (tem))
Jim Blandy's avatar
Jim Blandy committed
981 982
	    {
	      def = XSYMBOL (sym)->function;
Jim Blandy's avatar
Jim Blandy committed
983 984
	      if (!EQ (def, Qunbound))
		continue;
Jim Blandy's avatar
Jim Blandy committed
985
	    }
Jim Blandy's avatar
Jim Blandy committed
986
	  break;
Jim Blandy's avatar
Jim Blandy committed
987
	}
988
      /* Right now TEM is the result from SYM in ENVIRONMENT,
Jim Blandy's avatar
Jim Blandy committed
989
	 and if TEM is nil then DEF is SYM's function definition.  */
Jim Blandy's avatar
Jim Blandy committed
990
      if (NILP (tem))
Jim Blandy's avatar
Jim Blandy committed
991
	{
992
	  /* SYM is not mentioned in ENVIRONMENT.
Jim Blandy's avatar
Jim Blandy committed
993
	     Look at its function definition.  */
994
	  if (EQ (def, Qunbound) || !CONSP (def))
Jim Blandy's avatar
Jim Blandy committed
995 996
	    /* Not defined or definition not suitable */
	    break;
997
	  if (EQ (XCAR (def), Qautoload))
Jim Blandy's avatar
Jim Blandy committed
998 999
	    {
	      /* Autoloading function: will it be a macro when loaded?  */
1000
	      tem = Fnth (make_number (4), def);
1001
	      if (EQ (tem, Qt) || EQ (tem, Qmacro))
1002 1003
		/* Yes, load it and try again.  */
		{
1004 1005
		  struct gcpro gcpro1;
		  GCPRO1 (form);
1006
		  do_autoload (def, sym);
1007
		  UNGCPRO;
1008 1009 1010
		  continue;
		}
	      else
Jim Blandy's avatar
Jim Blandy committed
1011 1012
		break;
	    }
1013
	  else if (!EQ (XCAR (def), Qmacro))
Jim Blandy's avatar
Jim Blandy committed
1014
	    break;
1015
	  else expander = XCDR (def);
Jim Blandy's avatar
Jim Blandy committed
1016 1017 1018
	}
      else
	{
1019
	  expander = XCDR (tem);
Jim Blandy's avatar
Jim Blandy committed
1020
	  if (NILP (expander))
Jim Blandy's avatar
Jim Blandy committed
1021 1022
	    break;
	}
1023
      form = apply1 (expander, XCDR (form));
Jim Blandy's avatar
Jim Blandy committed
1024 1025 1026 1027 1028
    }
  return form;
}

DEFUN ("catch", Fcatch, Scatch, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
1029 1030 1031 1032 1033 1034 1035 1036 1037
       doc: /* Eval BODY allowing nonlocal exits using `throw'.
TAG is evalled to get the tag to use; it must not be nil.

Then the BODY is executed.
Within BODY, (throw TAG) with same tag exits BODY and exits this `catch'.
If no throw happens, `catch' returns the value of the last BODY form.
If a throw happens, it specifies the value to return from `catch'.
usage: (catch TAG BODY...)  */)
     (args)
Jim Blandy's avatar
Jim Blandy committed
1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071
     Lisp_Object args;
{
  register Lisp_Object tag;
  struct gcpro gcpro1;

  GCPRO1 (args);
  tag = Feval (Fcar (args));
  UNGCPRO;
  return internal_catch (tag, Fprogn, Fcdr (args));
}

/* Set up a catch, then call C function FUNC on argument ARG.
   FUNC should return a Lisp_Object.
   This is how catches are done from within C code. */

Lisp_Object
internal_catch (tag, func, arg)
     Lisp_Object tag;
     Lisp_Object (*func) ();
     Lisp_Object arg;
{
  /* This structure is made part of the chain `catchlist'.  */
  struct catchtag c;

  /* Fill in the components of c, and put it on the list.  */
  c.next = catchlist;
  c.tag = tag;
  c.val = Qnil;
  c.backlist = backtrace_list;
  c.handlerlist = handlerlist;
  c.lisp_eval_depth = lisp_eval_depth;
  c.pdlcount = specpdl_ptr - specpdl;
  c.poll_suppress_count = poll_suppress_count;
  c.gcpro = gcprolist;
1072
  c.byte_stack = byte_stack_list;
Jim Blandy's avatar
Jim Blandy committed
1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083
  catchlist = &c;

  /* Call FUNC.  */
  if (! _setjmp (c.jmp))
    c.val = (*func) (arg);

  /* Throw works by a longjmp that comes right here.  */
  catchlist = c.next;
  return c.val;
}

1084 1085
/* Unwind the specbind, catch, and handler stacks back to CATCH, and
   jump to that CATCH, returning VALUE as the value of that catch.
Jim Blandy's avatar
Jim Blandy committed
1086

1087 1088 1089
   This is the guts Fthrow and Fsignal; they differ only in the way
   they choose the catch tag to throw to.  A catch tag for a
   condition-case form has a TAG of Qnil.
Jim Blandy's avatar
Jim Blandy committed
1090

1091 1092 1093 1094 1095 1096 1097 1098
   Before each catch is discarded, unbind all special bindings and
   execute all unwind-protect clauses made above that catch.  Unwind
   the handler stack as we go, so that the proper handlers are in
   effect for each unwind-protect clause we run.  At the end, restore
   some static info saved in CATCH, and longjmp to the location
   specified in the

   This is used for correct unwinding in Fthrow and Fsignal.  */
Jim Blandy's avatar
Jim Blandy committed
1099 1100

static void
1101
unwind_to_catch (catch, value)
Jim Blandy's avatar
Jim Blandy committed
1102
     struct catchtag *catch;
1103
     Lisp_Object value;
Jim Blandy's avatar
Jim Blandy committed
1104 1105 1106
{
  register int last_time;

1107 1108 1109
  /* Save the value in the tag.  */
  catch->val = value;

1110