eval.c 78.7 KB
Newer Older
Jim Blandy's avatar
Jim Blandy committed
1
/* Evaluator for GNU Emacs Lisp interpreter.
2
   Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995 Free Software Foundation, Inc.
Jim Blandy's avatar
Jim Blandy committed
3 4 5 6 7

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
8
the Free Software Foundation; either version 2, or (at your option)
Jim Blandy's avatar
Jim Blandy committed
9 10 11 12 13 14 15 16 17 18 19 20
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
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


21
#include <config.h>
Jim Blandy's avatar
Jim Blandy committed
22
#include "lisp.h"
23
#include "blockinput.h"
Jim Blandy's avatar
Jim Blandy committed
24 25 26

#ifndef standalone
#include "commands.h"
Jim Blandy's avatar
Jim Blandy committed
27
#include "keyboard.h"
Jim Blandy's avatar
Jim Blandy committed
28 29 30 31 32 33 34 35 36 37 38 39 40 41
#else
#define INTERACTIVE 1
#endif

#include <setjmp.h>

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

struct backtrace
  {
    struct backtrace *next;
    Lisp_Object *function;
    Lisp_Object *args;	/* Points to vector of args. */
Jim Blandy's avatar
Jim Blandy committed
42 43 44
    int nargs;		/* Length of vector.
			   If nargs is UNEVALLED, args points to slot holding
			   list of unevalled args */
Jim Blandy's avatar
Jim Blandy committed
45 46 47 48 49 50 51
    char evalargs;
    /* Nonzero means call value of debugger when done with this operation. */
    char debug_on_exit;
  };

struct backtrace *backtrace_list;

52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69
/* 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.  */
Jim Blandy's avatar
Jim Blandy committed
70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
struct catchtag
  {
    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 catchtag *catchlist;

Lisp_Object Qautoload, Qmacro, Qexit, Qinteractive, Qcommandp, Qdefun;
Jim Blandy's avatar
Jim Blandy committed
87
Lisp_Object Qinhibit_quit, Vinhibit_quit, Vquit_flag;
Jim Blandy's avatar
Jim Blandy committed
88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121
Lisp_Object Qmocklisp_arguments, Vmocklisp_arguments, Qmocklisp;
Lisp_Object Qand_rest, Qand_optional;
Lisp_Object Qdebug_on_error;

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.  */
int specpdl_size;

/* Pointer to beginning of specpdl.  */
struct specbinding *specpdl;

/* Pointer to first unused element in specpdl.  */
struct specbinding *specpdl_ptr;

/* Maximum size allowed for specpdl allocation */
int max_specpdl_size;

/* Depth in Lisp evaluations and function calls.  */
int lisp_eval_depth;

/* Maximum allowed depth in Lisp evaluations and function calls.  */
int max_lisp_eval_depth;

/* Nonzero means enter debugger before next function call */
int debug_on_next_call;

Roland McGrath's avatar
Roland McGrath committed
122
/* List of conditions (non-nil atom means all) which cause a backtrace
123
   if an error is handled by the command loop's error handler.  */
Roland McGrath's avatar
Roland McGrath committed
124
Lisp_Object Vstack_trace_on_error;
Jim Blandy's avatar
Jim Blandy committed
125

Roland McGrath's avatar
Roland McGrath committed
126
/* List of conditions (non-nil atom means all) which enter the debugger
127
   if an error is handled by the command loop's error handler.  */
Roland McGrath's avatar
Roland McGrath committed
128
Lisp_Object Vdebug_on_error;
Jim Blandy's avatar
Jim Blandy committed
129

Karl Heuer's avatar
Karl Heuer committed
130 131 132 133
/* List of conditions and regexps specifying error messages which
   do not enter the debugger even if Vdebug_on_errors says they should.  */
Lisp_Object Vdebug_ignored_errors;

Jim Blandy's avatar
Jim Blandy committed
134
/* Nonzero means enter debugger if a quit signal
Roland McGrath's avatar
Roland McGrath committed
135
   is handled by the command loop's error handler. */
Jim Blandy's avatar
Jim Blandy committed
136 137
int debug_on_quit;

138 139 140 141 142 143 144
/* The value of num_nonmacro_input_chars as of the last time we
   started to enter the debugger.  If we decide to enter the debugger
   again when this is still equal to num_nonmacro_input_chars, then we
   know that the debugger itself has an error, and we should just
   signal the error instead of entering an infinite loop of debugger
   invocations.  */
int when_entered_debugger;
Jim Blandy's avatar
Jim Blandy committed
145 146 147 148 149

Lisp_Object Vdebugger;

void specbind (), record_unwind_protect ();

150 151
Lisp_Object run_hook_with_args ();

Jim Blandy's avatar
Jim Blandy committed
152 153 154 155 156 157
Lisp_Object funcall_lambda ();
extern Lisp_Object ml_apply (); /* Apply a mocklisp function to unevaluated argument list */

init_eval_once ()
{
  specpdl_size = 50;
158
  specpdl = (struct specbinding *) xmalloc (specpdl_size * sizeof (struct specbinding));
Jim Blandy's avatar
Jim Blandy committed
159 160
  max_specpdl_size = 600;
  max_lisp_eval_depth = 200;
161 162

  Vrun_hooks = Qnil;
Jim Blandy's avatar
Jim Blandy committed
163 164 165 166 167 168 169 170 171 172 173
}

init_eval ()
{
  specpdl_ptr = specpdl;
  catchlist = 0;
  handlerlist = 0;
  backtrace_list = 0;
  Vquit_flag = Qnil;
  debug_on_next_call = 0;
  lisp_eval_depth = 0;
174 175
  /* This is less than the initial value of num_nonmacro_input_chars.  */
  when_entered_debugger = -1;
Jim Blandy's avatar
Jim Blandy committed
176 177 178 179 180 181 182 183 184 185 186
}

Lisp_Object
call_debugger (arg)
     Lisp_Object arg;
{
  if (lisp_eval_depth + 20 > max_lisp_eval_depth)
    max_lisp_eval_depth = lisp_eval_depth + 20;
  if (specpdl_size + 40 > max_specpdl_size)
    max_specpdl_size = specpdl_size + 40;
  debug_on_next_call = 0;
187
  when_entered_debugger = num_nonmacro_input_chars;
Jim Blandy's avatar
Jim Blandy committed
188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213
  return apply1 (Vdebugger, arg);
}

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,
  "Eval args until one of them yields non-nil, then return that value.\n\
The remaining args are not evalled at all.\n\
If all args return nil, return nil.")
  (args)
     Lisp_Object args;
{
  register Lisp_Object val;
  Lisp_Object args_left;
  struct gcpro gcpro1;

Jim Blandy's avatar
Jim Blandy committed
214
  if (NILP(args))
Jim Blandy's avatar
Jim Blandy committed
215 216 217 218 219 220 221 222
    return Qnil;

  args_left = args;
  GCPRO1 (args_left);

  do
    {
      val = Feval (Fcar (args_left));
Jim Blandy's avatar
Jim Blandy committed
223
      if (!NILP (val))
Jim Blandy's avatar
Jim Blandy committed
224 225 226
	break;
      args_left = Fcdr (args_left);
    }
Jim Blandy's avatar
Jim Blandy committed
227
  while (!NILP(args_left));
Jim Blandy's avatar
Jim Blandy committed
228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243

  UNGCPRO;
  return val;
}

DEFUN ("and", Fand, Sand, 0, UNEVALLED, 0,
  "Eval args until one of them yields nil, then return nil.\n\
The remaining args are not evalled at all.\n\
If no arg yields nil, return the last arg's value.")
  (args)
     Lisp_Object args;
{
  register Lisp_Object val;
  Lisp_Object args_left;
  struct gcpro gcpro1;

Jim Blandy's avatar
Jim Blandy committed
244
  if (NILP(args))
Jim Blandy's avatar
Jim Blandy committed
245 246 247 248 249 250 251 252
    return Qt;

  args_left = args;
  GCPRO1 (args_left);

  do
    {
      val = Feval (Fcar (args_left));
Jim Blandy's avatar
Jim Blandy committed
253
      if (NILP (val))
Jim Blandy's avatar
Jim Blandy committed
254 255 256
	break;
      args_left = Fcdr (args_left);
    }
Jim Blandy's avatar
Jim Blandy committed
257
  while (!NILP(args_left));
Jim Blandy's avatar
Jim Blandy committed
258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277

  UNGCPRO;
  return val;
}

DEFUN ("if", Fif, Sif, 2, UNEVALLED, 0,
  "(if COND THEN ELSE...): if COND yields non-nil, do THEN, else do ELSE...\n\
Returns the value of THEN or the value of the last of the ELSE's.\n\
THEN must be one expression, but ELSE... can be zero or more expressions.\n\
If COND yields nil, and there are no ELSE's, the value is nil.")
  (args)
     Lisp_Object args;
{
  register Lisp_Object cond;
  struct gcpro gcpro1;

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

Jim Blandy's avatar
Jim Blandy committed
278
  if (!NILP (cond))
Jim Blandy's avatar
Jim Blandy committed
279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299
    return Feval (Fcar (Fcdr (args)));
  return Fprogn (Fcdr (Fcdr (args)));
}

DEFUN ("cond", Fcond, Scond, 0, UNEVALLED, 0,
  "(cond CLAUSES...): try each clause until one succeeds.\n\
Each clause looks like (CONDITION BODY...).  CONDITION is evaluated\n\
and, if the value is non-nil, this clause succeeds:\n\
then the expressions in BODY are evaluated and the last one's\n\
value is the value of the cond-form.\n\
If no clause succeeds, cond returns nil.\n\
If a clause has one element, as in (CONDITION),\n\
CONDITION's value if non-nil is returned from the cond-form.")
  (args)
     Lisp_Object args;
{
  register Lisp_Object clause, val;
  struct gcpro gcpro1;

  val = Qnil;
  GCPRO1 (args);
Jim Blandy's avatar
Jim Blandy committed
300
  while (!NILP (args))
Jim Blandy's avatar
Jim Blandy committed
301 302 303
    {
      clause = Fcar (args);
      val = Feval (Fcar (clause));
Jim Blandy's avatar
Jim Blandy committed
304
      if (!NILP (val))
Jim Blandy's avatar
Jim Blandy committed
305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330
	{
	  if (!EQ (XCONS (clause)->cdr, Qnil))
	    val = Fprogn (XCONS (clause)->cdr);
	  break;
	}
      args = XCONS (args)->cdr;
    }
  UNGCPRO;

  return val;
}

DEFUN ("progn", Fprogn, Sprogn, 0, UNEVALLED, 0,
  "(progn BODY...): eval BODY forms sequentially and return value of last one.")
  (args)
     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);
331
      while (!NILP (args) && (tem = Fcar (args), SYMBOLP (tem)))
Jim Blandy's avatar
Jim Blandy committed
332 333 334 335 336 337
	{
	  QUIT;
	  specbind (tem, val), args = Fcdr (args);
	}
    }

Jim Blandy's avatar
Jim Blandy committed
338
  if (NILP(args))
Jim Blandy's avatar
Jim Blandy committed
339 340 341 342 343 344 345 346 347 348
    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
349
  while (!NILP(args_left));
Jim Blandy's avatar
Jim Blandy committed
350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366

  UNGCPRO;
  return val;
}

DEFUN ("prog1", Fprog1, Sprog1, 1, UNEVALLED, 0,
  "(prog1 FIRST BODY...): eval FIRST and BODY sequentially; value from FIRST.\n\
The value of FIRST is saved during the evaluation of the remaining args,\n\
whose values are discarded.")
  (args)
     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
367
  if (NILP(args))
Jim Blandy's avatar
Jim Blandy committed
368 369 370 371 372 373 374 375 376 377 378 379 380 381
    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
382
  while (!NILP(args_left));
Jim Blandy's avatar
Jim Blandy committed
383 384 385 386 387 388

  UNGCPRO;
  return val;
}

DEFUN ("prog2", Fprog2, Sprog2, 2, UNEVALLED, 0,
Richard M. Stallman's avatar
Richard M. Stallman committed
389
  "(prog2 X Y BODY...): eval X, Y and BODY sequentially; value from Y.\n\
Jim Blandy's avatar
Jim Blandy committed
390 391 392 393 394 395 396 397 398 399 400 401
The value of Y is saved during the evaluation of the remaining args,\n\
whose values are discarded.")
  (args)
     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
402
  if (NILP (args))
Jim Blandy's avatar
Jim Blandy committed
403 404 405 406 407 408 409 410 411 412 413 414 415 416
    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
417
  while (!NILP (args_left));
Jim Blandy's avatar
Jim Blandy committed
418 419 420 421 422 423 424

  UNGCPRO;
  return val;
}

DEFUN ("setq", Fsetq, Ssetq, 0, UNEVALLED, 0,
  "(setq SYM VAL SYM VAL ...): set each SYM to the value of its VAL.\n\
Richard M. Stallman's avatar
Richard M. Stallman committed
425 426 427 428 429
The symbols SYM are variables; they are literal (not evaluated).\n\
The values VAL are expressions; they are evaluated.\n\
Thus, (setq x (1+ y)) sets `x' to the value of `(1+ y)'.\n\
The second VAL is not computed until after the first SYM is set, and so on;\n\
each VAL can use the new value of variables set earlier in the `setq'.\n\
Karl Heuer's avatar
Karl Heuer committed
430
The return value of the `setq' form is the value of the last VAL.")
Jim Blandy's avatar
Jim Blandy committed
431 432 433 434 435 436 437
  (args)
     Lisp_Object args;
{
  register Lisp_Object args_left;
  register Lisp_Object val, sym;
  struct gcpro gcpro1;

Jim Blandy's avatar
Jim Blandy committed
438
  if (NILP(args))
Jim Blandy's avatar
Jim Blandy committed
439 440 441 442 443 444 445 446 447 448 449 450
    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
451
  while (!NILP(args_left));
Jim Blandy's avatar
Jim Blandy committed
452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488

  UNGCPRO;
  return val;
}
     
DEFUN ("quote", Fquote, Squote, 1, UNEVALLED, 0,
  "Return the argument, without evaluating it.  `(quote x)' yields `x'.")
  (args)
     Lisp_Object args;
{
  return Fcar (args);
}
     
DEFUN ("function", Ffunction, Sfunction, 1, UNEVALLED, 0,
  "Like `quote', but preferred for objects which are functions.\n\
In byte compilation, `function' causes its argument to be compiled.\n\
`quote' cannot do that.")
  (args)
     Lisp_Object args;
{
  return Fcar (args);
}

DEFUN ("interactive-p", Finteractive_p, Sinteractive_p, 0, 0, 0,
  "Return t if function in which this appears was called interactively.\n\
This means that the function was called with call-interactively (which\n\
includes being called as the binding of a key)\n\
and input is currently coming from the keyboard (not in keyboard macro).")
  ()
{
  register struct backtrace *btp;
  register Lisp_Object fun;

  if (!INTERACTIVE)
    return Qnil;

  btp = backtrace_list;
Jim Blandy's avatar
Jim Blandy committed
489 490 491 492

  /* If this isn't a byte-compiled function, there may be a frame at
     the top for Finteractive_p itself.  If so, skip it.  */
  fun = Findirect_function (*btp->function);
493
  if (SUBRP (fun) && XSUBR (fun) == &Sinteractive_p)
Jim Blandy's avatar
Jim Blandy committed
494
    btp = btp->next;
Jim Blandy's avatar
Jim Blandy committed
495 496 497 498 499 500 501 502 503 504 505 506 507

  /* 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
508 509
    btp = btp->next;

Jim Blandy's avatar
Jim Blandy committed
510 511 512 513
  /* 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
514
  fun = Findirect_function (*btp->function);
515
  if (SUBRP (fun))
Jim Blandy's avatar
Jim Blandy committed
516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535
    return Qnil;
  /* 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))
    return Qt;
  return Qnil;
}

DEFUN ("defun", Fdefun, Sdefun, 2, UNEVALLED, 0,
  "(defun NAME ARGLIST [DOCSTRING] BODY...): define NAME as a function.\n\
The definition is (lambda ARGLIST [DOCSTRING] BODY...).\n\
See also the function `interactive'.")
  (args)
     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
536
  if (!NILP (Vpurify_flag))
Jim Blandy's avatar
Jim Blandy committed
537 538
    defn = Fpurecopy (defn);
  Ffset (fn_name, defn);
539
  LOADHIST_ATTACH (fn_name);
Jim Blandy's avatar
Jim Blandy committed
540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557
  return fn_name;
}

DEFUN ("defmacro", Fdefmacro, Sdefmacro, 2, UNEVALLED, 0,
  "(defmacro NAME ARGLIST [DOCSTRING] BODY...): define NAME as a macro.\n\
The definition is (macro lambda ARGLIST [DOCSTRING] BODY...).\n\
When the macro is called, as in (NAME ARGS...),\n\
the function (lambda ARGLIST BODY...) is applied to\n\
the list ARGS... as it appears in the expression,\n\
and the result should be a form to be evaluated instead of the original.")
  (args)
     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
558
  if (!NILP (Vpurify_flag))
Jim Blandy's avatar
Jim Blandy committed
559 560
    defn = Fpurecopy (defn);
  Ffset (fn_name, defn);
561
  LOADHIST_ATTACH (fn_name);
Jim Blandy's avatar
Jim Blandy committed
562 563 564 565 566 567 568 569 570
  return fn_name;
}

DEFUN ("defvar", Fdefvar, Sdefvar, 1, UNEVALLED, 0,
  "(defvar SYMBOL INITVALUE DOCSTRING): define SYMBOL as a variable.\n\
You are not required to define a variable in order to use it,\n\
but the definition can supply documentation and an initial value\n\
in a way that tags can recognize.\n\n\
INITVALUE is evaluated, and used to set SYMBOL, only if SYMBOL's value is void.\n\
571 572
If SYMBOL is buffer-local, its default value is what is set;\n\
 buffer-local values are not affected.\n\
Jim Blandy's avatar
Jim Blandy committed
573 574 575 576 577 578 579
INITVALUE and DOCSTRING are optional.\n\
If DOCSTRING starts with *, this variable is identified as a user option.\n\
 This means that M-x set-variable and M-x edit-options recognize it.\n\
If INITVALUE is missing, SYMBOL's value is not set.")
  (args)
     Lisp_Object args;
{
580
  register Lisp_Object sym, tem, tail;
Jim Blandy's avatar
Jim Blandy committed
581 582

  sym = Fcar (args);
583 584 585 586 587
  tail = Fcdr (args);
  if (!NILP (Fcdr (Fcdr (tail))))
    error ("too many arguments");

  if (!NILP (tail))
Jim Blandy's avatar
Jim Blandy committed
588 589
    {
      tem = Fdefault_boundp (sym);
Jim Blandy's avatar
Jim Blandy committed
590
      if (NILP (tem))
Jim Blandy's avatar
Jim Blandy committed
591 592
	Fset_default (sym, Feval (Fcar (Fcdr (args))));
    }
593 594
  tail = Fcdr (Fcdr (args));
  if (!NILP (Fcar (tail)))
Jim Blandy's avatar
Jim Blandy committed
595
    {
596
      tem = Fcar (tail);
Jim Blandy's avatar
Jim Blandy committed
597
      if (!NILP (Vpurify_flag))
Jim Blandy's avatar
Jim Blandy committed
598 599 600
	tem = Fpurecopy (tem);
      Fput (sym, Qvariable_documentation, tem);
    }
601
  LOADHIST_ATTACH (sym);
Jim Blandy's avatar
Jim Blandy committed
602 603 604 605 606 607 608
  return sym;
}

DEFUN ("defconst", Fdefconst, Sdefconst, 2, UNEVALLED, 0,
  "(defconst SYMBOL INITVALUE DOCSTRING): define SYMBOL as a constant variable.\n\
The intent is that programs do not change this value, but users may.\n\
Always sets the value of SYMBOL to the result of evalling INITVALUE.\n\
609 610
If SYMBOL is buffer-local, its default value is what is set;\n\
 buffer-local values are not affected.\n\
Jim Blandy's avatar
Jim Blandy committed
611 612 613 614 615 616 617 618 619 620 621 622 623 624
DOCSTRING is optional.\n\
If DOCSTRING starts with *, this variable is identified as a user option.\n\
 This means that M-x set-variable and M-x edit-options recognize it.\n\n\
Note: do not use `defconst' for user options in libraries that are not\n\
normally loaded, since it is useful for users to be able to specify\n\
their own values for such variables before loading the library.\n\
Since `defconst' unconditionally assigns the variable,\n\
it would override the user's choice.")
  (args)
     Lisp_Object args;
{
  register Lisp_Object sym, tem;

  sym = Fcar (args);
625 626 627
  if (!NILP (Fcdr (Fcdr (Fcdr (args)))))
    error ("too many arguments");

Jim Blandy's avatar
Jim Blandy committed
628 629
  Fset_default (sym, Feval (Fcar (Fcdr (args))));
  tem = Fcar (Fcdr (Fcdr (args)));
Jim Blandy's avatar
Jim Blandy committed
630
  if (!NILP (tem))
Jim Blandy's avatar
Jim Blandy committed
631
    {
Jim Blandy's avatar
Jim Blandy committed
632
      if (!NILP (Vpurify_flag))
Jim Blandy's avatar
Jim Blandy committed
633 634 635
	tem = Fpurecopy (tem);
      Fput (sym, Qvariable_documentation, tem);
    }
636
  LOADHIST_ATTACH (sym);
Jim Blandy's avatar
Jim Blandy committed
637 638 639 640 641 642 643
  return sym;
}

DEFUN ("user-variable-p", Fuser_variable_p, Suser_variable_p, 1, 1, 0,
  "Returns t if VARIABLE is intended to be set and modified by users.\n\
\(The alternative is a variable used internally in a Lisp program.)\n\
Determined by whether the first character of the documentation\n\
644
for the variable is `*'.")
Jim Blandy's avatar
Jim Blandy committed
645 646 647 648 649 650
  (variable)
     Lisp_Object variable;
{
  Lisp_Object documentation;
  
  documentation = Fget (variable, Qvariable_documentation);
651
  if (INTEGERP (documentation) && XINT (documentation) < 0)
Jim Blandy's avatar
Jim Blandy committed
652
    return Qt;
653 654 655 656 657 658 659 660
  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)
      && STRINGP (XCONS (documentation)->car)
      && INTEGERP (XCONS (documentation)->cdr)
      && XINT (XCONS (documentation)->cdr) < 0)
Jim Blandy's avatar
Jim Blandy committed
661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680
    return Qt;
  return Qnil;
}  

DEFUN ("let*", FletX, SletX, 1, UNEVALLED, 0,
  "(let* VARLIST BODY...): bind variables according to VARLIST then eval BODY.\n\
The value of the last form in BODY is returned.\n\
Each element of VARLIST is a symbol (which is bound to nil)\n\
or a list (SYMBOL VALUEFORM) (which binds SYMBOL to the value of VALUEFORM).\n\
Each VALUEFORM can refer to the symbols already bound by this VARLIST.")
  (args)
     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
681
  while (!NILP (varlist))
Jim Blandy's avatar
Jim Blandy committed
682 683 684
    {
      QUIT;
      elt = Fcar (varlist);
685
      if (SYMBOLP (elt))
Jim Blandy's avatar
Jim Blandy committed
686
	specbind (elt, Qnil);
Jim Blandy's avatar
Jim Blandy committed
687 688 689 690
      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
691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728
      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,
  "(let VARLIST BODY...): bind variables according to VARLIST then eval BODY.\n\
The value of the last form in BODY is returned.\n\
Each element of VARLIST is a symbol (which is bound to nil)\n\
or a list (SYMBOL VALUEFORM) (which binds SYMBOL to the value of VALUEFORM).\n\
All the VALUEFORMs are evalled before any symbols are bound.")
  (args)
     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
729
  for (argnum = 0; !NILP (varlist); varlist = Fcdr (varlist))
Jim Blandy's avatar
Jim Blandy committed
730 731 732
    {
      QUIT;
      elt = Fcar (varlist);
733
      if (SYMBOLP (elt))
Jim Blandy's avatar
Jim Blandy committed
734
	temps [argnum++] = Qnil;
Jim Blandy's avatar
Jim Blandy committed
735 736 737 738
      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
739 740 741 742 743 744 745
      else
	temps [argnum++] = Feval (Fcar (Fcdr (elt)));
      gcpro2.nvars = argnum;
    }
  UNGCPRO;

  varlist = Fcar (args);
Jim Blandy's avatar
Jim Blandy committed
746
  for (argnum = 0; !NILP (varlist); varlist = Fcdr (varlist))
Jim Blandy's avatar
Jim Blandy committed
747 748 749
    {
      elt = Fcar (varlist);
      tem = temps[argnum++];
750
      if (SYMBOLP (elt))
Jim Blandy's avatar
Jim Blandy committed
751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773
	specbind (elt, tem);
      else
	specbind (Fcar (elt), tem);
    }

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

DEFUN ("while", Fwhile, Swhile, 1, UNEVALLED, 0,
  "(while TEST BODY...): if TEST yields non-nil, eval BODY... and repeat.\n\
The order of execution is thus TEST, BODY, TEST, BODY and so on\n\
until TEST returns nil.")
  (args)
     Lisp_Object args;
{
  Lisp_Object test, body, tem;
  struct gcpro gcpro1, gcpro2;

  GCPRO2 (test, body);

  test = Fcar (args);
  body = Fcdr (args);
774 775
  while (tem = Feval (test),
	 (!EQ (Vmocklisp_arguments, Qt) ? XINT (tem) : !NILP (tem)))
Jim Blandy's avatar
Jim Blandy committed
776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791
    {
      QUIT;
      Fprogn (body);
    }

  UNGCPRO;
  return Qnil;
}

DEFUN ("macroexpand", Fmacroexpand, Smacroexpand, 1, 2, 0,
  "Return result of expanding macros at top level of FORM.\n\
If FORM is not a macro call, it is returned unchanged.\n\
Otherwise, the macro is expanded and the expansion is considered\n\
in place of FORM.  When a non-macro-call results, it is returned.\n\n\
The second optional arg ENVIRONMENT species an environment of macro\n\
definitions to shadow the loaded ones for use in file byte-compilation.")
792
  (form, environment)
Jim Blandy's avatar
Jim Blandy committed
793
     register Lisp_Object form;
794
     Lisp_Object environment;
Jim Blandy's avatar
Jim Blandy committed
795
{
Jim Blandy's avatar
Jim Blandy committed
796
  /* With cleanups from Hallvard Furuseth.  */
Jim Blandy's avatar
Jim Blandy committed
797 798 799 800 801 802
  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.  */
803
      if (!CONSP (form))
Jim Blandy's avatar
Jim Blandy committed
804
	break;
Jim Blandy's avatar
Jim Blandy committed
805 806 807
      /* Set SYM, give DEF and TEM right values in case SYM is not a symbol. */
      def = sym = XCONS (form)->car;
      tem = Qnil;
Jim Blandy's avatar
Jim Blandy committed
808 809
      /* Trace symbols aliases to other symbols
	 until we get a symbol that is not an alias.  */
810
      while (SYMBOLP (def))
Jim Blandy's avatar
Jim Blandy committed
811 812
	{
	  QUIT;
Jim Blandy's avatar
Jim Blandy committed
813
	  sym = def;
814
	  tem = Fassq (sym, environment);
Jim Blandy's avatar
Jim Blandy committed
815
	  if (NILP (tem))
Jim Blandy's avatar
Jim Blandy committed
816 817
	    {
	      def = XSYMBOL (sym)->function;
Jim Blandy's avatar
Jim Blandy committed
818 819
	      if (!EQ (def, Qunbound))
		continue;
Jim Blandy's avatar
Jim Blandy committed
820
	    }
Jim Blandy's avatar
Jim Blandy committed
821
	  break;
Jim Blandy's avatar
Jim Blandy committed
822
	}
823
      /* Right now TEM is the result from SYM in ENVIRONMENT,
Jim Blandy's avatar
Jim Blandy committed
824
	 and if TEM is nil then DEF is SYM's function definition.  */
Jim Blandy's avatar
Jim Blandy committed
825
      if (NILP (tem))
Jim Blandy's avatar
Jim Blandy committed
826
	{
827
	  /* SYM is not mentioned in ENVIRONMENT.
Jim Blandy's avatar
Jim Blandy committed
828
	     Look at its function definition.  */
829
	  if (EQ (def, Qunbound) || !CONSP (def))
Jim Blandy's avatar
Jim Blandy committed
830 831 832 833 834
	    /* Not defined or definition not suitable */
	    break;
	  if (EQ (XCONS (def)->car, Qautoload))
	    {
	      /* Autoloading function: will it be a macro when loaded?  */
835
	      tem = Fnth (make_number (4), def);
836
	      if (EQ (tem, Qt) || EQ (tem, Qmacro))
837 838 839 840 841 842
		/* Yes, load it and try again.  */
		{
		  do_autoload (def, sym);
		  continue;
		}
	      else
Jim Blandy's avatar
Jim Blandy committed
843 844 845 846 847 848 849 850 851
		break;
	    }
	  else if (!EQ (XCONS (def)->car, Qmacro))
	    break;
	  else expander = XCONS (def)->cdr;
	}
      else
	{
	  expander = XCONS (tem)->cdr;
Jim Blandy's avatar
Jim Blandy committed
852
	  if (NILP (expander))
Jim Blandy's avatar
Jim Blandy committed
853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911
	    break;
	}
      form = apply1 (expander, XCONS (form)->cdr);
    }
  return form;
}

DEFUN ("catch", Fcatch, Scatch, 1, UNEVALLED, 0,
  "(catch TAG BODY...): eval BODY allowing nonlocal exits using `throw'.\n\
TAG is evalled to get the tag to use.  Then the BODY is executed.\n\
Within BODY, (throw TAG) with same tag exits BODY and exits this `catch'.\n\
If no throw happens, `catch' returns the value of the last BODY form.\n\
If a throw happens, it specifies the value to return from `catch'.")
  (args)
     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;
  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;
}

912 913
/* 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
914

915 916 917
   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
918

919 920 921 922 923 924 925 926
   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
927 928

static void
929
unwind_to_catch (catch, value)
Jim Blandy's avatar
Jim Blandy committed
930
     struct catchtag *catch;
931
     Lisp_Object value;
Jim Blandy's avatar
Jim Blandy committed
932 933 934
{
  register int last_time;

935 936 937
  /* Save the value in the tag.  */
  catch->val = value;

938
  /* Restore the polling-suppression count.  */
939
  set_poll_suppress_count (catch->poll_suppress_count);
940

Jim Blandy's avatar
Jim Blandy committed
941 942 943
  do
    {
      last_time = catchlist == catch;
944 945 946

      /* Unwind the specpdl stack, and then restore the proper set of
         handlers.  */
Jim Blandy's avatar
Jim Blandy committed
947 948 949 950 951 952 953 954 955
      unbind_to (catchlist->pdlcount, Qnil);
      handlerlist = catchlist->handlerlist;
      catchlist = catchlist->next;
    }
  while (! last_time);

  gcprolist = catch->gcpro;
  backtrace_list = catch->backlist;
  lisp_eval_depth = catch->lisp_eval_depth;
956 957
  
  _longjmp (catch->jmp, 1);
Jim Blandy's avatar
Jim Blandy committed
958 959 960 961 962
}

DEFUN ("throw", Fthrow, Sthrow, 2, 2, 0,
  "(throw TAG VALUE): throw to the catch for TAG and return VALUE from it.\n\
Both TAG and VALUE are evalled.")
963 964
  (tag, value)
     register Lisp_Object tag, value;
Jim Blandy's avatar
Jim Blandy committed
965 966 967 968 969
{
  register struct catchtag *c;

  while (1)
    {
Jim Blandy's avatar
Jim Blandy committed
970
      if (!NILP (tag))
Jim Blandy's avatar
Jim Blandy committed
971 972 973
	for (c = catchlist; c; c = c->next)
	  {
	    if (EQ (c->tag, tag))
974
	      unwind_to_catch (c, value);
Jim Blandy's avatar
Jim Blandy committed
975
	  }
976
      tag = Fsignal (Qno_catch, Fcons (tag, Fcons (value, Qnil)));
Jim Blandy's avatar
Jim Blandy committed
977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015
    }
}


DEFUN ("unwind-protect", Funwind_protect, Sunwind_protect, 1, UNEVALLED, 0,
  "Do BODYFORM, protecting with UNWINDFORMS.\n\
Usage looks like (unwind-protect BODYFORM UNWINDFORMS...).\n\
If BODYFORM completes normally, its value is returned\n\
after executing the UNWINDFORMS.\n\
If BODYFORM exits nonlocally, the UNWINDFORMS are executed anyway.")
  (args)
     Lisp_Object args;
{
  Lisp_Object val;
  int count = specpdl_ptr - specpdl;

  record_unwind_protect (0, Fcdr (args));
  val = Feval (Fcar (args));
  return unbind_to (count, val);  
}

/* Chain of condition handlers currently in effect.
   The elements of this chain are contained in the stack frames
   of Fcondition_case and internal_condition_case.
   When an error is signaled (by calling Fsignal, below),
   this chain is searched for an element that applies.  */

struct handler *handlerlist;

DEFUN ("condition-case", Fcondition_case, Scondition_case, 2, UNEVALLED, 0,
  "Regain control when an error is signaled.\n\
Usage looks like (condition-case VAR BODYFORM HANDLERS...).\n\
executes BODYFORM and returns its value if no error happens.\n\
Each element of HANDLERS looks like (CONDITION-NAME BODY...)\n\
where the BODY is made of Lisp expressions.\n\n\
A handler is applicable to an error\n\
if CONDITION-NAME is one of the error's condition names.\n\
If an error happens, the first applicable handler is run.\n\
\n\
1016 1017 1018
The car of a handler may be a list of condition names\n\
instead of a single condition name.\n\
\n\
Jim Blandy's avatar
Jim Blandy committed
1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031
When a handler handles an error,\n\
control returns to the condition-case and the handler BODY... is executed\n\
with VAR bound to (SIGNALED-CONDITIONS . SIGNAL-DATA).\n\
VAR may be nil; then you do not get access to the signal information.\n\
\n\
The value of the last BODY form is returned from the condition-case.\n\
See also the function `signal' for more info.")
  (args)
     Lisp_Object args;
{
  Lisp_Object val;
  struct catchtag c;
  struct handler h;
1032
  register Lisp_Object var, bodyform, handlers;
Jim Blandy's avatar
Jim Blandy committed
1033

1034 1035 1036 1037 1038 1039 1040 1041 1042
  var      = Fcar (args);
  bodyform = Fcar (Fcdr (args));
  handlers = Fcdr (Fcdr (args));
  CHECK_SYMBOL (var, 0);

  for (val = handlers; ! NILP (val); val = Fcdr (val))
    {
      Lisp_Object tem;
      tem = Fcar (val);
1043 1044 1045 1046
      if (! (NILP (tem)
	     || (CONSP (tem)
		 && (SYMBOLP (XCONS (tem)->car)
		     || CONSP (XCONS (tem)->car)))))
1047 1048
	error ("Invalid condition handler", tem);
    }
Jim Blandy's avatar
Jim Blandy committed
1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059

  c.tag = Qnil;
  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;
  if (_setjmp (c.jmp))
    {
Jim Blandy's avatar
Jim Blandy committed
1060
      if (!NILP (h.var))
1061 1062
        specbind (h.var, c.val);
      val = Fprogn (Fcdr (h.chosen_clause));
1063 1064 1065 1066

      /* Note that this just undoes the binding of h.var; whoever
	 longjumped to us unwound the stack to c.pdlcount before
	 throwing. */
Jim Blandy's avatar
Jim Blandy committed
1067 1068 1069 1070 1071 1072
      unbind_to (c.pdlcount, Qnil);
      return val;
    }
  c.next = catchlist;
  catchlist = &c;
  
1073 1074
  h.var = var;
  h.handler = handlers;
Jim Blandy's avatar
Jim Blandy committed
1075 1076 1077 1078
  h.next = handlerlist;
  h.tag = &c;
  handlerlist = &h;

1079
  val = Feval (bodyform);
Jim Blandy's avatar
Jim Blandy committed
1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094
  catchlist = c.next;
  handlerlist = h.next;
  return val;
}

Lisp_Object
internal_condition_case (bfun, handlers, hfun)
     Lisp_Object (*bfun) ();
     Lisp_Object handlers;
     Lisp_Object (*hfun) ();
{
  Lisp_Object val;
  struct catchtag c;
  struct handler h;

1095 1096 1097 1098 1099
  /* Since Fsignal resets this to 0, it had better be 0 now
     or else we have a potential bug.  */
  if (interrupt_input_blocked != 0)
    abort ();

Jim Blandy's avatar
Jim Blandy committed
1100 1101 1102 1103 1104 1105 1106 1107 1108 1109
  c.tag = Qnil;
  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;
  if (_setjmp (c.jmp))
    {
1110
      return (*hfun) (c.val);
Jim Blandy's avatar
Jim Blandy committed
1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125
    }
  c.next = catchlist;
  catchlist = &c;
  h.handler = handlers;
  h.var = Qnil;
  h.next = handlerlist;
  h.tag = &c;
  handlerlist = &h;

  val = (*bfun) ();
  catchlist = c.next;
  handlerlist = h.next;
  return val;
}

1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146
Lisp_Object
internal_condition_case_1 (bfun, arg, handlers, hfun)
     Lisp_Object (*bfun) ();
     Lisp_Object arg;
     Lisp_Object handlers;
     Lisp_Object (*hfun) ();
{
  Lisp_Object val;
  struct catchtag c;
  struct handler h;

  c.tag = Qnil;
  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;
  if (_setjmp (c.jmp))
    {
1147
      return (*hfun) (c.val);
1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162
    }
  c.next = catchlist;
  catchlist = &c;
  h.handler = handlers;
  h.var = Qnil;
  h.next = handlerlist;
  h.tag = &c;
  handlerlist = &h;

  val = (*bfun) (arg);
  catchlist = c.next;
  handlerlist = h.next;
  return val;
}

Jim Blandy's avatar
Jim Blandy committed
1163 1164 1165
static Lisp_Object find_handler_clause ();

DEFUN ("signal", Fsignal, Ssignal, 2, 2, 0,
1166
  "Signal an error.  Args are ERROR-SYMBOL and associated DATA.\n\
Jim Blandy's avatar
Jim Blandy committed
1167
This function does not return.\n\n\
1168
An error symbol is a symbol with an `error-conditions' property\n\
Jim Blandy's avatar
Jim Blandy committed
1169 1170 1171 1172 1173 1174 1175
that is a list of condition names.\n\
A handler for any of those names will get to handle this signal.\n\
The symbol `error' should normally be one of them.\n\
\n\
DATA should be a list.  Its elements are printed as part of the error message.\n\
If the signal is handled, DATA is made available to the handler.\n\
See also the function `condition-case'.")
1176 1177
  (error_symbol, data)
     Lisp_Object error_symbol, data;
Jim Blandy's avatar
Jim Blandy committed
1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189
{
  register struct handler *allhandlers = handlerlist;
  Lisp_Object conditions;
  extern int gc_in_progress;
  extern int waiting_for_input;
  Lisp_Object debugger_value;

  quit_error_check ();
  immediate_quit = 0;
  if (gc_in_progress || waiting_for_input)
    abort ();

Jim Blandy's avatar
Jim Blandy committed
1190
#ifdef HAVE_X_WINDOWS
Jim Blandy's avatar
Jim Blandy committed
1191
  TOTALLY_UNBLOCK_INPUT;
Jim Blandy's avatar
Jim Blandy committed
1192
#endif
Jim Blandy's avatar
Jim Blandy committed
1193

1194
  conditions = Fget (error_symbol, Qerror_conditions);
Jim Blandy's avatar
Jim Blandy committed
1195 1196 1197 1198 1199

  for (; handlerlist; handlerlist = handlerlist->next)
    {
      register Lisp_Object clause;
      clause = find_handler_clause (handlerlist->handler, conditions,
1200
				    error_symbol, data, &debugger_value);
Jim Blandy's avatar
Jim Blandy committed
1201 1202 1203 1204 1205 1206 1207 1208 1209

#if 0 /* Most callers are not prepared to handle gc if this returns.
	 So, since this feature is not very useful, take it out.  */
      /* If have called debugger and user wants to continue,
	 just return nil.  */
      if (EQ (clause, Qlambda))
	return debugger_value;
#else
      if (EQ (clause, Qlambda))
1210
	{
1211 1212
	  /* We can't return values to code which signaled an error, but we
	     can continue code which has signaled a quit.  */
1213
	  if (EQ (error_symbol, Qquit))
1214 1215
	    return Qnil;
	  else
1216
	    error ("Cannot return from the debugger in an error");
1217
	}
Jim Blandy's avatar
Jim Blandy committed
1218 1219
#endif

Jim Blandy's avatar
Jim Blandy committed
1220
      if (!NILP (clause))
Jim Blandy's avatar
Jim Blandy committed
1221
	{
1222
	  Lisp_Object unwind_data;
Jim Blandy's avatar
Jim Blandy committed
1223
	  struct handler *h = handlerlist;
1224

Jim Blandy's avatar
Jim Blandy committed
1225
	  handlerlist = allhandlers;
1226
	  if (EQ (data, memory_signal_data))
1227 1228 1229 1230 1231
	    unwind_data = memory_signal_data;
	  else
	    unwind_data = Fcons (error_symbol, data);
	  h->chosen_clause = clause;
	  unwind_to_catch (h->tag, unwind_data);
Jim Blandy's avatar
Jim Blandy committed
1232 1233 1234 1235 1236 1237
	}
    }

  handlerlist = allhandlers;
  /* If no handler is present now, try to run the debugger,
     and if that fails, throw to top level.  */
1238
  find_handler_clause (Qerror, conditions, error_symbol, data, &debugger_value);
Jim Blandy's avatar
Jim Blandy committed
1239 1240 1241
  Fthrow (Qtop_level, Qt);
}

Roland McGrath's avatar
Roland McGrath committed
1242 1243 1244 1245 1246 1247 1248
/* Return nonzero iff LIST is a non-nil atom or
   a list containing one of CONDITIONS.  */

static int
wants_debugger (list, conditions)
     Lisp_Object list, conditions;
{
1249
  if (NILP (list))
Roland McGrath's avatar
Roland McGrath committed
1250 1251 1252 1253
    return 0;
  if (! CONSP (list))
    return 1;

1254
  while (CONSP (conditions))
Roland McGrath's avatar
Roland McGrath committed
1255
    {
1256 1257 1258 1259
      Lisp_Object this, tail;
      this = XCONS (conditions)->car;
      for (tail = list; CONSP (tail); tail = XCONS (tail)->cdr)
	if (EQ (XCONS (tail)->car, this))
Roland McGrath's avatar
Roland McGrath committed
1260 1261 1262
	  return 1;
      conditions = XCONS (conditions)->cdr;
    }
1263
  return 0;
Roland McGrath's avatar
Roland McGrath committed
1264 1265
}

Karl Heuer's avatar
Karl Heuer committed
1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304
/* Return 1 if an error with condition-symbols CONDITIONS,
   and described by SIGNAL-DATA, should skip the debugger
   according to debugger-ignore-errors.  */

static int
skip_debugger (conditions, data)
     Lisp_Object conditions, data;
{
  Lisp_Object tail;
  int first_string = 1;
  Lisp_Object error_message;

  for (tail = Vdebug_ignored_errors; CONSP (tail);
       tail = XCONS (tail)->cdr)
    {
      if (STRINGP (XCONS (tail)->car))
	{
	  if (first_string)
	    {
	      error_message = Ferror_message_string (data);
	      first_string = 0;
	    }
	  if (fast_string_match (XCONS (tail)->car, error_message) >= 0)
	    return 1;
	}
      else
	{
	  Lisp_Object contail;

	  for (contail = conditions; CONSP (contail);
	       contail = XCONS (contail)->cdr)
	    if (EQ (XCONS (tail)->car, XCONS (contail)->car))
	      return 1;
	}
    }

  return 0;
}

Roland McGrath's avatar
Roland McGrath committed
1305 1306
/* Value of Qlambda means we have called debugger and user has continued.
   Store value returned from debugger into *DEBUGGER_VALUE_PTR.  */
Jim Blandy's avatar
Jim Blandy committed
1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319

static Lisp_Object
find_handler_clause (handlers, conditions, sig, data, debugger_value_ptr)
     Lisp_Object handlers, conditions, sig, data;
     Lisp_Object *debugger_value_ptr;
{
  register Lisp_Object h;
  register Lisp_Object tem;

  if (EQ (handlers, Qt))  /* t is used by handlers for all conditions, set up by C code.  */
    return