eval.c 111 KB
Newer Older
Jim Blandy's avatar
Jim Blandy committed
1
/* Evaluator for GNU Emacs Lisp interpreter.
Glenn Morris's avatar
Glenn Morris committed
2

Paul Eggert's avatar
Paul Eggert committed
3
Copyright (C) 1985-1987, 1993-1995, 1999-2015 Free Software Foundation,
4
Inc.
Jim Blandy's avatar
Jim Blandy committed
5 6 7

This file is part of GNU Emacs.

8
GNU Emacs is free software: you can redistribute it and/or modify
Jim Blandy's avatar
Jim Blandy committed
9
it under the terms of the GNU General Public License as published by
10 11
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Jim Blandy's avatar
Jim Blandy committed
12 13 14 15 16 17 18

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
19
along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
Jim Blandy's avatar
Jim Blandy committed
20 21


22
#include <config.h>
23
#include <limits.h>
24
#include <stdio.h>
Jim Blandy's avatar
Jim Blandy committed
25
#include "lisp.h"
26
#include "blockinput.h"
Jim Blandy's avatar
Jim Blandy committed
27
#include "commands.h"
Jim Blandy's avatar
Jim Blandy committed
28
#include "keyboard.h"
29
#include "dispextern.h"
30
#include "buffer.h"
31

32
/* Chain of condition and catch handlers currently in effect.  */
33 34 35

struct handler *handlerlist;

36 37 38 39 40
#ifdef DEBUG_GCPRO
/* Count levels of GCPRO to detect failure to UNGCPRO.  */
int gcpro_level;
#endif

Jim Blandy's avatar
Jim Blandy committed
41 42 43
/* 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:
44
   (FUN . ODEF) for a defun, (0 . OFEATURES) for a provide.  */
Jim Blandy's avatar
Jim Blandy committed
45 46 47

Lisp_Object Vautoload_queue;

48 49 50 51 52
/* This holds either the symbol `run-hooks' or nil.
   It is nil at an early stage of startup, and when Emacs
   is shutting down.  */
Lisp_Object Vrun_hooks;

53 54
/* Current number of specbindings allocated in specpdl, not counting
   the dummy entry specpdl[-1].  */
55

56
ptrdiff_t specpdl_size;
Jim Blandy's avatar
Jim Blandy committed
57

58 59
/* Pointer to beginning of specpdl.  A dummy entry specpdl[-1] exists
   only so that its address can be taken.  */
60

61
union specbinding *specpdl;
Jim Blandy's avatar
Jim Blandy committed
62 63

/* Pointer to first unused element in specpdl.  */
64

65
union specbinding *specpdl_ptr;
Jim Blandy's avatar
Jim Blandy committed
66 67

/* Depth in Lisp evaluations and function calls.  */
68

69
EMACS_INT lisp_eval_depth;
Jim Blandy's avatar
Jim Blandy committed
70

71
/* The value of num_nonmacro_input_events as of the last time we
72
   started to enter the debugger.  If we decide to enter the debugger
73
   again when this is still equal to num_nonmacro_input_events, then we
74 75 76
   know that the debugger itself has an error, and we should just
   signal the error instead of entering an infinite loop of debugger
   invocations.  */
77

78
static EMACS_INT when_entered_debugger;
Jim Blandy's avatar
Jim Blandy committed
79

80 81
/* The function from which the last `signal' was called.  Set in
   Fsignal.  */
82
/* FIXME: We should probably get rid of this!  */
83 84
Lisp_Object Vsignaling_function;

85 86
/* If non-nil, Lisp code must not be run since some part of Emacs is in
   an inconsistent state.  Currently unused.  */
87 88
Lisp_Object inhibit_lisp_code;

89 90 91 92 93 94 95
/* These would ordinarily be static, but they need to be visible to GDB.  */
bool backtrace_p (union specbinding *) EXTERNALLY_VISIBLE;
Lisp_Object *backtrace_args (union specbinding *) EXTERNALLY_VISIBLE;
Lisp_Object backtrace_function (union specbinding *) EXTERNALLY_VISIBLE;
union specbinding *backtrace_next (union specbinding *) EXTERNALLY_VISIBLE;
union specbinding *backtrace_top (void) EXTERNALLY_VISIBLE;

96
static Lisp_Object funcall_lambda (Lisp_Object, ptrdiff_t, Lisp_Object *);
97
static Lisp_Object apply_lambda (Lisp_Object, Lisp_Object, ptrdiff_t);
98

99
static Lisp_Object
100
specpdl_symbol (union specbinding *pdl)
101 102
{
  eassert (pdl->kind >= SPECPDL_LET);
103
  return pdl->let.symbol;
104 105 106
}

static Lisp_Object
107
specpdl_old_value (union specbinding *pdl)
108 109
{
  eassert (pdl->kind >= SPECPDL_LET);
110
  return pdl->let.old_value;
111 112
}

113 114 115 116 117 118 119
static void
set_specpdl_old_value (union specbinding *pdl, Lisp_Object val)
{
  eassert (pdl->kind >= SPECPDL_LET);
  pdl->let.old_value = val;
}

120
static Lisp_Object
121
specpdl_where (union specbinding *pdl)
122 123
{
  eassert (pdl->kind > SPECPDL_LET);
124
  return pdl->let.where;
125 126 127
}

static Lisp_Object
128
specpdl_arg (union specbinding *pdl)
129 130
{
  eassert (pdl->kind == SPECPDL_UNWIND);
131
  return pdl->unwind.arg;
132 133
}

134
Lisp_Object
135
backtrace_function (union specbinding *pdl)
136 137
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
138
  return pdl->bt.function;
139 140 141
}

static ptrdiff_t
142
backtrace_nargs (union specbinding *pdl)
143 144
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
145
  return pdl->bt.nargs;
146 147
}

148
Lisp_Object *
149
backtrace_args (union specbinding *pdl)
150 151
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
152
  return pdl->bt.args;
153 154 155
}

static bool
156
backtrace_debug_on_exit (union specbinding *pdl)
157 158
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
159
  return pdl->bt.debug_on_exit;
160 161
}

162
/* Functions to modify slots of backtrace records.  */
163

164
static void
165
set_backtrace_args (union specbinding *pdl, Lisp_Object *args, ptrdiff_t nargs)
166 167 168
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
  pdl->bt.args = args;
169
  pdl->bt.nargs = nargs;
170
}
171

172
static void
173 174 175 176 177
set_backtrace_debug_on_exit (union specbinding *pdl, bool doe)
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
  pdl->bt.debug_on_exit = doe;
}
178 179 180

/* Helper functions to scan the backtrace.  */

181 182
bool
backtrace_p (union specbinding *pdl)
183
{ return pdl >= specpdl; }
184

185
union specbinding *
186
backtrace_top (void)
187
{
188
  union specbinding *pdl = specpdl_ptr - 1;
189
  while (backtrace_p (pdl) && pdl->kind != SPECPDL_BACKTRACE)
190 191
    pdl--;
  return pdl;
192
}
193

194 195
union specbinding *
backtrace_next (union specbinding *pdl)
196
{
197 198 199 200
  pdl--;
  while (backtrace_p (pdl) && pdl->kind != SPECPDL_BACKTRACE)
    pdl--;
  return pdl;
201 202
}

203

Andreas Schwab's avatar
Andreas Schwab committed
204
void
205
init_eval_once (void)
Jim Blandy's avatar
Jim Blandy committed
206
{
207
  enum { size = 50 };
208
  union specbinding *pdlvec = xmalloc ((size + 1) * sizeof *specpdl);
209
  specpdl_size = size;
210
  specpdl = specpdl_ptr = pdlvec + 1;
211
  /* Don't forget to update docs (lispref node "Local Variables").  */
Stefan Monnier's avatar
Stefan Monnier committed
212
  max_specpdl_size = 1300; /* 1000 is not enough for CEDET's c-by.el.  */
213
  max_lisp_eval_depth = 800;
214 215

  Vrun_hooks = Qnil;
Jim Blandy's avatar
Jim Blandy committed
216 217
}

218 219
static struct handler handlerlist_sentinel;

Andreas Schwab's avatar
Andreas Schwab committed
220
void
221
init_eval (void)
Jim Blandy's avatar
Jim Blandy committed
222
{
223 224
  gcprolist = 0;
  byte_stack_list = 0;
Jim Blandy's avatar
Jim Blandy committed
225
  specpdl_ptr = specpdl;
226 227 228 229 230 231 232 233 234 235
  { /* Put a dummy catcher at top-level so that handlerlist is never NULL.
       This is important since handlerlist->nextfree holds the freelist
       which would otherwise leak every time we unwind back to top-level.   */
    struct handler *c;
    handlerlist = handlerlist_sentinel.nextfree = &handlerlist_sentinel;
    PUSH_HANDLER (c, Qunbound, CATCHER);
    eassert (c == &handlerlist_sentinel);
    handlerlist_sentinel.nextfree = NULL;
    handlerlist_sentinel.next = NULL;
  }
Jim Blandy's avatar
Jim Blandy committed
236 237 238
  Vquit_flag = Qnil;
  debug_on_next_call = 0;
  lisp_eval_depth = 0;
239
#ifdef DEBUG_GCPRO
240
  gcpro_level = 0;
241
#endif
242
  /* This is less than the initial value of num_nonmacro_input_events.  */
243
  when_entered_debugger = -1;
Jim Blandy's avatar
Jim Blandy committed
244 245
}

246
/* Unwind-protect function used by call_debugger.  */
247

248
static void
249
restore_stack_limits (Lisp_Object data)
250 251 252 253 254
{
  max_specpdl_size = XINT (XCAR (data));
  max_lisp_eval_depth = XINT (XCDR (data));
}

255 256
static void grow_specpdl (void);

257 258
/* Call the Lisp debugger, giving it argument ARG.  */

259
Lisp_Object
260
call_debugger (Lisp_Object arg)
Jim Blandy's avatar
Jim Blandy committed
261
{
262
  bool debug_while_redisplaying;
263
  ptrdiff_t count = SPECPDL_INDEX ();
264
  Lisp_Object val;
265 266 267
  EMACS_INT old_depth = max_lisp_eval_depth;
  /* Do not allow max_specpdl_size less than actual depth (Bug#16603).  */
  EMACS_INT old_max = max (max_specpdl_size, count);
268 269 270 271

  if (lisp_eval_depth + 40 > max_lisp_eval_depth)
    max_lisp_eval_depth = lisp_eval_depth + 40;

272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287
  /* While debugging Bug#16603, previous value of 100 was found
     too small to avoid specpdl overflow in the debugger itself.  */
  if (max_specpdl_size - 200 < count)
    max_specpdl_size = count + 200;

  if (old_max == count)
    {
      /* We can enter the debugger due to specpdl overflow (Bug#16603).  */
      specpdl_ptr--;
      grow_specpdl ();
    }

  /* Restore limits after leaving the debugger.  */
  record_unwind_protect (restore_stack_limits,
			 Fcons (make_number (old_max),
				make_number (old_depth)));
288

289
#ifdef HAVE_WINDOW_SYSTEM
290 291
  if (display_hourglass_p)
    cancel_hourglass ();
292 293
#endif

Jim Blandy's avatar
Jim Blandy committed
294
  debug_on_next_call = 0;
295
  when_entered_debugger = num_nonmacro_input_events;
296 297 298 299 300

  /* 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;
301 302
  specbind (intern ("debugger-may-continue"),
	    debug_while_redisplaying ? Qnil : Qt);
303
  specbind (Qinhibit_redisplay, Qnil);
304
  specbind (Qinhibit_debugger, Qt);
305 306 307

#if 0 /* Binding this prevents execution of Lisp code during
	 redisplay, which necessarily leads to display problems.  */
308
  specbind (Qinhibit_eval_during_redisplay, Qt);
309
#endif
310

311 312 313 314
  val = apply1 (Vdebugger, arg);

  /* Interrupting redisplay and resuming it later is not safe under
     all circumstances.  So, when the debugger returns, abort the
315
     interrupted redisplay by going back to the top-level.  */
316 317 318
  if (debug_while_redisplaying)
    Ftop_level ();

319
  return unbind_to (count, val);
Jim Blandy's avatar
Jim Blandy committed
320 321
}

322
static void
323
do_debug_on_call (Lisp_Object code, ptrdiff_t count)
Jim Blandy's avatar
Jim Blandy committed
324 325
{
  debug_on_next_call = 0;
326
  set_backtrace_debug_on_exit (specpdl + count, true);
327
  call_debugger (list1 (code));
Jim Blandy's avatar
Jim Blandy committed
328 329 330 331 332 333 334
}

/* 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
335 336 337
       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.
Juanma Barranquero's avatar
Juanma Barranquero committed
338
usage: (or CONDITIONS...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
339
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
340
{
341
  register Lisp_Object val = Qnil;
Jim Blandy's avatar
Jim Blandy committed
342 343
  struct gcpro gcpro1;

344
  GCPRO1 (args);
Jim Blandy's avatar
Jim Blandy committed
345

346
  while (CONSP (args))
Jim Blandy's avatar
Jim Blandy committed
347
    {
348
      val = eval_sub (XCAR (args));
Jim Blandy's avatar
Jim Blandy committed
349
      if (!NILP (val))
Jim Blandy's avatar
Jim Blandy committed
350
	break;
351
      args = XCDR (args);
Jim Blandy's avatar
Jim Blandy committed
352 353 354 355 356 357 358
    }

  UNGCPRO;
  return val;
}

DEFUN ("and", Fand, Sand, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
359
       doc: /* Eval args until one of them yields nil, then return nil.
Pavel Janík's avatar
Pavel Janík committed
360 361
The remaining args are not evalled at all.
If no arg yields nil, return the last arg's value.
Juanma Barranquero's avatar
Juanma Barranquero committed
362
usage: (and CONDITIONS...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
363
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
364
{
365
  register Lisp_Object val = Qt;
Jim Blandy's avatar
Jim Blandy committed
366 367
  struct gcpro gcpro1;

368
  GCPRO1 (args);
Jim Blandy's avatar
Jim Blandy committed
369

370
  while (CONSP (args))
Jim Blandy's avatar
Jim Blandy committed
371
    {
372
      val = eval_sub (XCAR (args));
Jim Blandy's avatar
Jim Blandy committed
373
      if (NILP (val))
Jim Blandy's avatar
Jim Blandy committed
374
	break;
375
      args = XCDR (args);
Jim Blandy's avatar
Jim Blandy committed
376 377 378 379 380 381 382
    }

  UNGCPRO;
  return val;
}

DEFUN ("if", Fif, Sif, 2, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
383
       doc: /* If COND yields non-nil, do THEN, else do ELSE...
Pavel Janík's avatar
Pavel Janík committed
384 385 386
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.
387
usage: (if COND THEN ELSE...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
388
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
389
{
390
  Lisp_Object cond;
Jim Blandy's avatar
Jim Blandy committed
391 392 393
  struct gcpro gcpro1;

  GCPRO1 (args);
394
  cond = eval_sub (XCAR (args));
Jim Blandy's avatar
Jim Blandy committed
395 396
  UNGCPRO;

Jim Blandy's avatar
Jim Blandy committed
397
  if (!NILP (cond))
398 399
    return eval_sub (Fcar (XCDR (args)));
  return Fprogn (XCDR (XCDR (args)));
Jim Blandy's avatar
Jim Blandy committed
400 401 402
}

DEFUN ("cond", Fcond, Scond, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
403 404 405 406 407
       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.
Glenn Morris's avatar
Glenn Morris committed
408 409
If a clause has one element, as in (CONDITION), then the cond-form
returns CONDITION's value, if that is non-nil.
Pavel Janík's avatar
Pavel Janík committed
410
If no clause succeeds, cond returns nil.
411
usage: (cond CLAUSES...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
412
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
413
{
414
  Lisp_Object val = args;
Jim Blandy's avatar
Jim Blandy committed
415 416 417
  struct gcpro gcpro1;

  GCPRO1 (args);
418
  while (CONSP (args))
Jim Blandy's avatar
Jim Blandy committed
419
    {
420
      Lisp_Object clause = XCAR (args);
421
      val = eval_sub (Fcar (clause));
Jim Blandy's avatar
Jim Blandy committed
422
      if (!NILP (val))
Jim Blandy's avatar
Jim Blandy committed
423
	{
424
	  if (!NILP (XCDR (clause)))
425
	    val = Fprogn (XCDR (clause));
Jim Blandy's avatar
Jim Blandy committed
426 427
	  break;
	}
428
      args = XCDR (args);
Jim Blandy's avatar
Jim Blandy committed
429 430 431 432 433 434
    }
  UNGCPRO;

  return val;
}

Paul Eggert's avatar
Paul Eggert committed
435
DEFUN ("progn", Fprogn, Sprogn, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
436
       doc: /* Eval BODY forms sequentially and return value of last one.
Juanma Barranquero's avatar
Juanma Barranquero committed
437
usage: (progn BODY...)  */)
438
  (Lisp_Object body)
Jim Blandy's avatar
Jim Blandy committed
439
{
440
  Lisp_Object val = Qnil;
Jim Blandy's avatar
Jim Blandy committed
441 442
  struct gcpro gcpro1;

443
  GCPRO1 (body);
Jim Blandy's avatar
Jim Blandy committed
444

445
  while (CONSP (body))
Jim Blandy's avatar
Jim Blandy committed
446
    {
447 448
      val = eval_sub (XCAR (body));
      body = XCDR (body);
Jim Blandy's avatar
Jim Blandy committed
449 450 451 452 453 454
    }

  UNGCPRO;
  return val;
}

Paul Eggert's avatar
Paul Eggert committed
455
/* Evaluate BODY sequentially, discarding its value.  Suitable for
456 457 458 459 460 461 462 463
   record_unwind_protect.  */

void
unwind_body (Lisp_Object body)
{
  Fprogn (body);
}

Jim Blandy's avatar
Jim Blandy committed
464
DEFUN ("prog1", Fprog1, Sprog1, 1, UNEVALLED, 0,
465
       doc: /* Eval FIRST and BODY sequentially; return value from FIRST.
Pavel Janík's avatar
Pavel Janík committed
466 467
The value of FIRST is saved during the evaluation of the remaining args,
whose values are discarded.
468
usage: (prog1 FIRST BODY...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
469
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
470 471
{
  Lisp_Object val;
472
  Lisp_Object args_left;
Jim Blandy's avatar
Jim Blandy committed
473 474 475
  struct gcpro gcpro1, gcpro2;

  args_left = args;
476
  val = args;
Jim Blandy's avatar
Jim Blandy committed
477 478
  GCPRO2 (args, val);

479 480 481
  val = eval_sub (XCAR (args_left));
  while (CONSP (args_left = XCDR (args_left)))
    eval_sub (XCAR (args_left));
Jim Blandy's avatar
Jim Blandy committed
482 483 484 485 486 487

  UNGCPRO;
  return val;
}

DEFUN ("prog2", Fprog2, Sprog2, 2, UNEVALLED, 0,
488
       doc: /* Eval FORM1, FORM2 and BODY sequentially; return value from FORM2.
489 490 491
The value of FORM2 is saved during the evaluation of the
remaining args, whose values are discarded.
usage: (prog2 FORM1 FORM2 BODY...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
492
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
493
{
494
  struct gcpro gcpro1;
Jim Blandy's avatar
Jim Blandy committed
495

496 497
  GCPRO1 (args);
  eval_sub (XCAR (args));
498 499
  UNGCPRO;
  return Fprog1 (XCDR (args));
Jim Blandy's avatar
Jim Blandy committed
500 501 502
}

DEFUN ("setq", Fsetq, Ssetq, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
503 504 505 506 507 508 509
       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.
Juanma Barranquero's avatar
Juanma Barranquero committed
510
usage: (setq [SYM VAL]...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
511
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
512
{
513
  Lisp_Object val, sym, lex_binding;
Jim Blandy's avatar
Jim Blandy committed
514

515 516 517 518 519 520
  val = args;
  if (CONSP (args))
    {
      Lisp_Object args_left = args;
      struct gcpro gcpro1;
      GCPRO1 (args);
Jim Blandy's avatar
Jim Blandy committed
521

522 523 524 525 526 527 528 529 530 531 532 533 534 535
      do
	{
	  val = eval_sub (Fcar (XCDR (args_left)));
	  sym = XCAR (args_left);

	  /* Like for eval_sub, we do not check declared_special here since
	     it's been done when let-binding.  */
	  if (!NILP (Vinternal_interpreter_environment) /* Mere optimization!  */
	      && SYMBOLP (sym)
	      && !NILP (lex_binding
			= Fassq (sym, Vinternal_interpreter_environment)))
	    XSETCDR (lex_binding, val); /* SYM is lexically bound.  */
	  else
	    Fset (sym, val);	/* SYM is dynamically bound.  */
Jim Blandy's avatar
Jim Blandy committed
536

537 538 539
	  args_left = Fcdr (XCDR (args_left));
	}
      while (CONSP (args_left));
540

541
      UNGCPRO;
Jim Blandy's avatar
Jim Blandy committed
542 543 544 545
    }

  return val;
}
546

Jim Blandy's avatar
Jim Blandy committed
547
DEFUN ("quote", Fquote, Squote, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
548
       doc: /* Return the argument, without evaluating it.  `(quote x)' yields `x'.
549 550 551 552 553 554 555 556
Warning: `quote' does not construct its return value, but just returns
the value that was pre-constructed by the Lisp reader (see info node
`(elisp)Printed Representation').
This means that '(a . b) is not identical to (cons 'a 'b): the former
does not cons.  Quoting should be reserved for constants that will
never be modified by side-effects, unless you like self-modifying code.
See the common pitfall in info node `(elisp)Rearrangement' for an example
of unexpected results when a quoted object is modified.
Pavel Janík's avatar
Pavel Janík committed
557
usage: (quote ARG)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
558
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
559
{
560
  if (CONSP (XCDR (args)))
561
    xsignal2 (Qwrong_number_of_arguments, Qquote, Flength (args));
562
  return XCAR (args);
Jim Blandy's avatar
Jim Blandy committed
563
}
564

Jim Blandy's avatar
Jim Blandy committed
565
DEFUN ("function", Ffunction, Sfunction, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
566 567 568 569
       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)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
570
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
571
{
572 573
  Lisp_Object quoted = XCAR (args);

574
  if (CONSP (XCDR (args)))
575
    xsignal2 (Qwrong_number_of_arguments, Qfunction, Flength (args));
576 577 578 579

  if (!NILP (Vinternal_interpreter_environment)
      && CONSP (quoted)
      && EQ (XCAR (quoted), Qlambda))
580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596
    { /* This is a lambda expression within a lexical environment;
	 return an interpreted closure instead of a simple lambda.  */
      Lisp_Object cdr = XCDR (quoted);
      Lisp_Object tmp = cdr;
      if (CONSP (tmp)
	  && (tmp = XCDR (tmp), CONSP (tmp))
	  && (tmp = XCAR (tmp), CONSP (tmp))
	  && (EQ (QCdocumentation, XCAR (tmp))))
	{ /* Handle the special (:documentation <form>) to build the docstring
	     dynamically.  */
	  Lisp_Object docstring = eval_sub (Fcar (XCDR (tmp)));
	  CHECK_STRING (docstring);
	  cdr = Fcons (XCAR (cdr), Fcons (docstring, XCDR (XCDR (cdr))));
	}
      return Fcons (Qclosure, Fcons (Vinternal_interpreter_environment,
				     cdr));
    }
597 598 599
  else
    /* Simply quote the argument.  */
    return quoted;
Jim Blandy's avatar
Jim Blandy committed
600 601
}

602

603
DEFUN ("defvaralias", Fdefvaralias, Sdefvaralias, 2, 3, 0,
604
       doc: /* Make NEW-ALIAS a variable alias for symbol BASE-VARIABLE.
Richard M. Stallman's avatar
Richard M. Stallman committed
605
Aliased variables always have the same value; setting one sets the other.
606
Third arg DOCSTRING, if non-nil, is documentation for NEW-ALIAS.  If it is
607 608 609 610
omitted or nil, NEW-ALIAS gets the documentation string of BASE-VARIABLE,
or of the variable at the end of the chain of aliases, if BASE-VARIABLE is
itself an alias.  If NEW-ALIAS is bound, and BASE-VARIABLE is not,
then the value of BASE-VARIABLE is set to that of NEW-ALIAS.
611
The return value is BASE-VARIABLE.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
612
  (Lisp_Object new_alias, Lisp_Object base_variable, Lisp_Object docstring)
Gerd Moellmann's avatar
Gerd Moellmann committed
613 614
{
  struct Lisp_Symbol *sym;
615

616 617
  CHECK_SYMBOL (new_alias);
  CHECK_SYMBOL (base_variable);
Gerd Moellmann's avatar
Gerd Moellmann committed
618

619
  sym = XSYMBOL (new_alias);
620 621

  if (sym->constant)
Stefan Monnier's avatar
Stefan Monnier committed
622 623
    /* Not sure why, but why not?  */
    error ("Cannot make a constant an alias");
624 625 626 627 628 629 630 631 632

  switch (sym->redirect)
    {
    case SYMBOL_FORWARDED:
      error ("Cannot make an internal variable an alias");
    case SYMBOL_LOCALIZED:
      error ("Don't know how to make a localized variable an alias");
    }

633
  /* http://lists.gnu.org/archive/html/emacs-devel/2008-04/msg00834.html
634 635 636 637
     If n_a is bound, but b_v is not, set the value of b_v to n_a,
     so that old-code that affects n_a before the aliasing is setup
     still works.  */
  if (NILP (Fboundp (base_variable)))
638
    set_internal (base_variable, find_symbol_value (new_alias), Qnil, 1);
639 640

  {
641
    union specbinding *p;
642

Paul Eggert's avatar
Paul Eggert committed
643
    for (p = specpdl_ptr; p > specpdl; )
644 645
      if ((--p)->kind >= SPECPDL_LET
	  && (EQ (new_alias, specpdl_symbol (p))))
646 647 648
	error ("Don't know how to make a let-bound variable an alias");
  }

649
  sym->declared_special = 1;
650
  XSYMBOL (base_variable)->declared_special = 1;
651 652
  sym->redirect = SYMBOL_VARALIAS;
  SET_SYMBOL_ALIAS (sym, XSYMBOL (base_variable));
653 654
  sym->constant = SYMBOL_CONSTANT_P (base_variable);
  LOADHIST_ATTACH (new_alias);
655 656
  /* Even if docstring is nil: remove old docstring.  */
  Fput (new_alias, Qvariable_documentation, docstring);
657

658
  return base_variable;
Gerd Moellmann's avatar
Gerd Moellmann committed
659 660
}

661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705
static union specbinding *
default_toplevel_binding (Lisp_Object symbol)
{
  union specbinding *binding = NULL;
  union specbinding *pdl = specpdl_ptr;
  while (pdl > specpdl)
    {
      switch ((--pdl)->kind)
	{
	case SPECPDL_LET_DEFAULT:
	case SPECPDL_LET:
	  if (EQ (specpdl_symbol (pdl), symbol))
	    binding = pdl;
	  break;
	}
    }
  return binding;
}

DEFUN ("default-toplevel-value", Fdefault_toplevel_value, Sdefault_toplevel_value, 1, 1, 0,
       doc: /* Return SYMBOL's toplevel default value.
"Toplevel" means outside of any let binding.  */)
  (Lisp_Object symbol)
{
  union specbinding *binding = default_toplevel_binding (symbol);
  Lisp_Object value
    = binding ? specpdl_old_value (binding) : Fdefault_value (symbol);
  if (!EQ (value, Qunbound))
    return value;
  xsignal1 (Qvoid_variable, symbol);
}

DEFUN ("set-default-toplevel-value", Fset_default_toplevel_value,
       Sset_default_toplevel_value, 2, 2, 0,
       doc: /* Set SYMBOL's toplevel default value to VALUE.
"Toplevel" means outside of any let binding.  */)
     (Lisp_Object symbol, Lisp_Object value)
{
  union specbinding *binding = default_toplevel_binding (symbol);
  if (binding)
    set_specpdl_old_value (binding, value);
  else
    Fset_default (symbol, value);
  return Qnil;
}
Gerd Moellmann's avatar
Gerd Moellmann committed
706

Jim Blandy's avatar
Jim Blandy committed
707
DEFUN ("defvar", Fdefvar, Sdefvar, 1, UNEVALLED, 0,
Juanma Barranquero's avatar
Juanma Barranquero committed
708
       doc: /* Define SYMBOL as a variable, and return SYMBOL.
709 710 711 712 713 714 715 716 717
You are not required to define a variable in order to use it, but
defining it lets you supply an initial value and documentation, which
can be referred to by the Emacs help facilities and other programming
tools.  The `defvar' form also declares the variable as \"special\",
so that it is always dynamically bound even if `lexical-binding' is t.

The optional argument 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.
Pavel Janík's avatar
Pavel Janík committed
718
If INITVALUE is missing, SYMBOL's value is not set.
719 720 721 722 723 724 725

If SYMBOL has a local binding, then this form affects the local
binding.  This is usually not what you want.  Thus, if you need to
load a file defining variables, with this form or with `defconst' or
`defcustom', you should always load that file _outside_ any bindings
for these variables.  \(`defconst' and `defcustom' behave similarly in
this respect.)
726 727 728 729 730

The optional argument DOCSTRING is a documentation string for the
variable.

To define a user option, use `defcustom' instead of `defvar'.
731
usage: (defvar SYMBOL &optional INITVALUE DOCSTRING)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
732
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
733
{
734
  Lisp_Object sym, tem, tail;
Jim Blandy's avatar
Jim Blandy committed
735

736 737
  sym = XCAR (args);
  tail = XCDR (args);
738

739
  if (CONSP (tail))
Jim Blandy's avatar
Jim Blandy committed
740
    {
741 742 743 744 745
      if (CONSP (XCDR (tail)) && CONSP (XCDR (XCDR (tail))))
	error ("Too many arguments");

      tem = Fdefault_boundp (sym);

746 747
      /* Do it before evaluating the initial value, for self-references.  */
      XSYMBOL (sym)->declared_special = 1;
748

Jim Blandy's avatar
Jim Blandy committed
749
      if (NILP (tem))
750
	Fset_default (sym, eval_sub (XCAR (tail)));
751 752 753
      else
	{ /* Check if there is really a global binding rather than just a let
	     binding that shadows the global unboundness of the var.  */
754 755
	  union specbinding *binding = default_toplevel_binding (sym);
	  if (binding && EQ (specpdl_old_value (binding), Qunbound))
756
	    {
757
	      set_specpdl_old_value (binding, eval_sub (XCAR (tail)));
758 759
	    }
	}
760
      tail = XCDR (tail);
761 762
      tem = Fcar (tail);
      if (!NILP (tem))
763 764 765 766 767
	{
	  if (!NILP (Vpurify_flag))
	    tem = Fpurecopy (tem);
	  Fput (sym, Qvariable_documentation, tem);
	}
768
      LOADHIST_ATTACH (sym);
Jim Blandy's avatar
Jim Blandy committed
769
    }
770 771 772 773 774
  else if (!NILP (Vinternal_interpreter_environment)
	   && !XSYMBOL (sym)->declared_special)
    /* A simple (defvar foo) with lexical scoping does "nothing" except
       declare that var to be dynamically scoped *locally* (i.e. within
       the current file or let-block).  */
775 776
    Vinternal_interpreter_environment
      = Fcons (sym, Vinternal_interpreter_environment);
777
  else
778 779 780 781 782
    {
      /* Simple (defvar <var>) should not count as a definition at all.
	 It could get in the way of other definitions, and unloading this
	 package could try to make the variable unbound.  */
    }
Andreas Schwab's avatar
Andreas Schwab committed
783

Jim Blandy's avatar
Jim Blandy committed
784 785 786 787
  return sym;
}

DEFUN ("defconst", Fdefconst, Sdefconst, 2, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
788
       doc: /* Define SYMBOL as a constant variable.
789 790 791 792 793 794 795 796 797 798 799 800 801
This declares that neither programs nor users should ever change the
value.  This constancy is not actually enforced by Emacs Lisp, but
SYMBOL is marked as a special variable so that it is never lexically
bound.

The `defconst' form 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.  If SYMBOL has a
local binding, then this form sets the local binding's value.
However, you should normally not make local bindings for variables
defined with this form.

The optional DOCSTRING specifies the variable's documentation string.
802
usage: (defconst SYMBOL INITVALUE [DOCSTRING])  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
803
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
804
{
805
  Lisp_Object sym, tem;
Jim Blandy's avatar
Jim Blandy committed
806

807 808
  sym = XCAR (args);
  if (CONSP (Fcdr (XCDR (XCDR (args)))))
809
    error ("Too many arguments");
810

811
  tem = eval_sub (Fcar (XCDR (args)));
812 813 814
  if (!NILP (Vpurify_flag))
    tem = Fpurecopy (tem);
  Fset_default (sym, tem);
815
  XSYMBOL (sym)->declared_special = 1;
816
  tem = Fcar (XCDR (XCDR (args)));
Jim Blandy's avatar
Jim Blandy committed
817
  if (!NILP (tem))
Jim Blandy's avatar
Jim Blandy committed
818
    {
Jim Blandy's avatar
Jim Blandy committed
819
      if (!NILP (Vpurify_flag))
Jim Blandy's avatar
Jim Blandy committed
820 821 822
	tem = Fpurecopy (tem);
      Fput (sym, Qvariable_documentation, tem);
    }
823
  Fput (sym, Qrisky_local_variable, Qt);
824
  LOADHIST_ATTACH (sym);
Jim Blandy's avatar
Jim Blandy committed
825 826 827
  return sym;
}

828 829 830 831 832 833 834 835 836 837 838
/* Make SYMBOL lexically scoped.  */
DEFUN ("internal-make-var-non-special", Fmake_var_non_special,
       Smake_var_non_special, 1, 1, 0,
       doc: /* Internal function.  */)
     (Lisp_Object symbol)
{
  CHECK_SYMBOL (symbol);
  XSYMBOL (symbol)->declared_special = 0;
  return Qnil;
}

Jim Blandy's avatar
Jim Blandy committed
839 840

DEFUN ("let*", FletX, SletX, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
841 842 843 844 845
       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.
846
usage: (let* VARLIST BODY...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
847
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
848
{
849
  Lisp_Object varlist, var, val, elt, lexenv;
850
  ptrdiff_t count = SPECPDL_INDEX ();
Jim Blandy's avatar
Jim Blandy committed
851 852 853 854
  struct gcpro gcpro1, gcpro2, gcpro3;

  GCPRO3 (args, elt, varlist);

855 856
  lexenv = Vinternal_interpreter_environment;

857
  varlist = XCAR (args);
858
  while (CONSP (varlist))
Jim Blandy's avatar
Jim Blandy committed
859 860
    {
      QUIT;
861 862

      elt = XCAR (varlist);
863
      if (SYMBOLP (elt))
864 865 866 867
	{
	  var = elt;
	  val = Qnil;
	}
Jim Blandy's avatar
Jim Blandy committed
868
      else if (! NILP (Fcdr (Fcdr (elt))))
869
	signal_error ("`let' bindings can have only one value-form", elt);
Jim Blandy's avatar
Jim Blandy committed
870 871
      else
	{
872
	  var = Fcar (elt);
873
	  val = eval_sub (Fcar (Fcdr (elt)));
Jim Blandy's avatar
Jim Blandy committed
874
	}
875

876 877 878
      if (!NILP (lexenv) && SYMBOLP (var)
	  && !XSYMBOL (var)->declared_special
	  && NILP (Fmemq (var, Vinternal_interpreter_environment)))
879 880 881
	/* Lexically bind VAR by adding it to the interpreter's binding
	   alist.  */
	{
882 883 884 885 886 887 888 889 890
	  Lisp_Object newenv
	    = Fcons (Fcons (var, val), Vinternal_interpreter_environment);
	  if (EQ (Vinternal_interpreter_environment, lexenv))
	    /* Save the old lexical environment on the specpdl stack,
	       but only for the first lexical binding, since we'll never
	       need to revert to one of the intermediate ones.  */
	    specbind (Qinternal_interpreter_environment, newenv);
	  else
	    Vinternal_interpreter_environment = newenv;
Jim Blandy's avatar
Jim Blandy committed
891
	}
892 893 894 895
      else
	specbind (var, val);

      varlist = XCDR (varlist);
Jim Blandy's avatar
Jim Blandy committed
896 897
    }
  UNGCPRO;
898
  val = Fprogn (XCDR (args));
Jim Blandy's avatar
Jim Blandy committed
899 900 901 902
  return unbind_to (count, val);
}

DEFUN ("let", Flet, Slet, 1, UNEVALLED, 0,