eval.c 103 KB
Newer Older
Jim Blandy's avatar
Jim Blandy committed
1
/* Evaluator for GNU Emacs Lisp interpreter.
2 3
   Copyright (C) 1985-1987, 1993-1995, 1999-2013 Free Software
   Foundation, Inc.
Jim Blandy's avatar
Jim Blandy committed
4 5 6

This file is part of GNU Emacs.

7
GNU Emacs is free software: you can redistribute it and/or modify
Jim Blandy's avatar
Jim Blandy committed
8
it under the terms of the GNU General Public License as published by
9 10
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Jim Blandy's avatar
Jim Blandy committed
11 12 13 14 15 16 17

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
18
along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
Jim Blandy's avatar
Jim Blandy committed
19 20


21
#include <config.h>
22
#include <limits.h>
23
#include <stdio.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"
29
#include "frame.h"		/* For XFRAME.  */
Jim Blandy's avatar
Jim Blandy committed
30

31 32 33 34
#if HAVE_X_WINDOWS
#include "xterm.h"
#endif

35 36 37
#if !BYTE_MARK_STACK
static
#endif
Jim Blandy's avatar
Jim Blandy committed
38 39
struct catchtag *catchlist;

40 41 42 43 44 45 46 47 48 49 50
/* 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.  */

#if !BYTE_MARK_STACK
static
#endif
struct handler *handlerlist;

51 52 53 54 55
#ifdef DEBUG_GCPRO
/* Count levels of GCPRO to detect failure to UNGCPRO.  */
int gcpro_level;
#endif

56
Lisp_Object Qautoload, Qmacro, Qexit, Qinteractive, Qcommandp;
57
Lisp_Object Qinhibit_quit;
58 59
Lisp_Object Qand_rest;
static Lisp_Object Qand_optional;
60
static Lisp_Object Qinhibit_debugger;
61
static Lisp_Object Qdeclare;
62 63
Lisp_Object Qinternal_interpreter_environment, Qclosure;

Paul Eggert's avatar
Paul Eggert committed
64
static Lisp_Object Qdebug;
Jim Blandy's avatar
Jim Blandy committed
65

66 67 68
/* This holds either the symbol `run-hooks' or nil.
   It is nil at an early stage of startup, and when Emacs
   is shutting down.  */
69

Jim Blandy's avatar
Jim Blandy committed
70 71 72 73 74
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:
75
   (FUN . ODEF) for a defun, (0 . OFEATURES) for a provide.  */
Jim Blandy's avatar
Jim Blandy committed
76 77 78

Lisp_Object Vautoload_queue;

79 80
/* Current number of specbindings allocated in specpdl, not counting
   the dummy entry specpdl[-1].  */
81

82
ptrdiff_t specpdl_size;
Jim Blandy's avatar
Jim Blandy committed
83

84 85
/* Pointer to beginning of specpdl.  A dummy entry specpdl[-1] exists
   only so that its address can be taken.  */
86

87
union specbinding *specpdl;
Jim Blandy's avatar
Jim Blandy committed
88 89

/* Pointer to first unused element in specpdl.  */
90

91
union specbinding *specpdl_ptr;
Jim Blandy's avatar
Jim Blandy committed
92 93

/* Depth in Lisp evaluations and function calls.  */
94

95
static EMACS_INT lisp_eval_depth;
Jim Blandy's avatar
Jim Blandy committed
96

97
/* The value of num_nonmacro_input_events as of the last time we
98
   started to enter the debugger.  If we decide to enter the debugger
99
   again when this is still equal to num_nonmacro_input_events, then we
100 101 102
   know that the debugger itself has an error, and we should just
   signal the error instead of entering an infinite loop of debugger
   invocations.  */
103

104
static EMACS_INT when_entered_debugger;
Jim Blandy's avatar
Jim Blandy committed
105

106 107
/* The function from which the last `signal' was called.  Set in
   Fsignal.  */
108
/* FIXME: We should probably get rid of this!  */
109 110
Lisp_Object Vsignaling_function;

111 112 113 114 115 116
/* If non-nil, Lisp code must not be run since some part of Emacs is
   in an inconsistent state.  Currently, x-create-frame uses this to
   avoid triggering window-configuration-change-hook while the new
   frame is half-initialized.  */
Lisp_Object inhibit_lisp_code;

117 118 119 120 121 122 123
/* 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;

124
static Lisp_Object funcall_lambda (Lisp_Object, ptrdiff_t, Lisp_Object *);
125
static Lisp_Object apply_lambda (Lisp_Object fun, Lisp_Object args);
126

127
static Lisp_Object
128
specpdl_symbol (union specbinding *pdl)
129 130
{
  eassert (pdl->kind >= SPECPDL_LET);
131
  return pdl->let.symbol;
132 133 134
}

static Lisp_Object
135
specpdl_old_value (union specbinding *pdl)
136 137
{
  eassert (pdl->kind >= SPECPDL_LET);
138
  return pdl->let.old_value;
139 140 141
}

static Lisp_Object
142
specpdl_where (union specbinding *pdl)
143 144
{
  eassert (pdl->kind > SPECPDL_LET);
145
  return pdl->let.where;
146 147 148
}

static Lisp_Object
149
specpdl_arg (union specbinding *pdl)
150 151
{
  eassert (pdl->kind == SPECPDL_UNWIND);
152
  return pdl->unwind.arg;
153 154 155
}

static specbinding_func
156
specpdl_func (union specbinding *pdl)
157 158
{
  eassert (pdl->kind == SPECPDL_UNWIND);
159
  return pdl->unwind.func;
160 161
}

162
Lisp_Object
163
backtrace_function (union specbinding *pdl)
164 165
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
166
  return pdl->bt.function;
167 168 169
}

static ptrdiff_t
170
backtrace_nargs (union specbinding *pdl)
171 172
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
173
  return pdl->bt.nargs;
174 175
}

176
Lisp_Object *
177
backtrace_args (union specbinding *pdl)
178 179
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
180
  return pdl->bt.args;
181 182 183
}

static bool
184
backtrace_debug_on_exit (union specbinding *pdl)
185 186
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
187
  return pdl->bt.debug_on_exit;
188 189
}

190
/* Functions to modify slots of backtrace records.  */
191

192
static void
193 194 195 196 197
set_backtrace_args (union specbinding *pdl, Lisp_Object *args)
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
  pdl->bt.args = args;
}
198

199
static void
200 201 202 203 204
set_backtrace_nargs (union specbinding *pdl, ptrdiff_t n)
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
  pdl->bt.nargs = n;
}
205

206
static void
207 208 209 210 211
set_backtrace_debug_on_exit (union specbinding *pdl, bool doe)
{
  eassert (pdl->kind == SPECPDL_BACKTRACE);
  pdl->bt.debug_on_exit = doe;
}
212 213 214

/* Helper functions to scan the backtrace.  */

215 216
bool
backtrace_p (union specbinding *pdl)
217
{ return pdl >= specpdl; }
218

219
union specbinding *
220
backtrace_top (void)
221
{
222
  union specbinding *pdl = specpdl_ptr - 1;
223
  while (backtrace_p (pdl) && pdl->kind != SPECPDL_BACKTRACE)
224 225
    pdl--;
  return pdl;
226
}
227

228 229
union specbinding *
backtrace_next (union specbinding *pdl)
230
{
231 232 233 234
  pdl--;
  while (backtrace_p (pdl) && pdl->kind != SPECPDL_BACKTRACE)
    pdl--;
  return pdl;
235 236
}

237

Andreas Schwab's avatar
Andreas Schwab committed
238
void
239
init_eval_once (void)
Jim Blandy's avatar
Jim Blandy committed
240
{
241
  enum { size = 50 };
242
  union specbinding *pdlvec = xmalloc ((size + 1) * sizeof *specpdl);
243
  specpdl_size = size;
244
  specpdl = specpdl_ptr = pdlvec + 1;
245
  /* Don't forget to update docs (lispref node "Local Variables").  */
Stefan Monnier's avatar
Stefan Monnier committed
246
  max_specpdl_size = 1300; /* 1000 is not enough for CEDET's c-by.el.  */
247
  max_lisp_eval_depth = 600;
248 249

  Vrun_hooks = Qnil;
Jim Blandy's avatar
Jim Blandy committed
250 251
}

Andreas Schwab's avatar
Andreas Schwab committed
252
void
253
init_eval (void)
Jim Blandy's avatar
Jim Blandy committed
254 255 256 257 258 259 260
{
  specpdl_ptr = specpdl;
  catchlist = 0;
  handlerlist = 0;
  Vquit_flag = Qnil;
  debug_on_next_call = 0;
  lisp_eval_depth = 0;
261
#ifdef DEBUG_GCPRO
262
  gcpro_level = 0;
263
#endif
264
  /* This is less than the initial value of num_nonmacro_input_events.  */
265
  when_entered_debugger = -1;
Jim Blandy's avatar
Jim Blandy committed
266 267
}

268
/* Unwind-protect function used by call_debugger.  */
269 270

static Lisp_Object
271
restore_stack_limits (Lisp_Object data)
272 273 274
{
  max_specpdl_size = XINT (XCAR (data));
  max_lisp_eval_depth = XINT (XCDR (data));
275
  return Qnil;
276 277 278 279
}

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

280
Lisp_Object
281
call_debugger (Lisp_Object arg)
Jim Blandy's avatar
Jim Blandy committed
282
{
283
  bool debug_while_redisplaying;
284
  ptrdiff_t count = SPECPDL_INDEX ();
285
  Lisp_Object val;
286
  EMACS_INT old_max = max_specpdl_size;
287

288 289
  /* Temporarily bump up the stack limits,
     so the debugger won't run out of stack.  */
290

291 292 293 294 295 296 297 298 299
  max_specpdl_size += 1;
  record_unwind_protect (restore_stack_limits,
			 Fcons (make_number (old_max),
				make_number (max_lisp_eval_depth)));
  max_specpdl_size = old_max;

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

300
  if (max_specpdl_size - 100 < SPECPDL_INDEX ())
301
    max_specpdl_size = SPECPDL_INDEX () + 100;
302

303
#ifdef HAVE_WINDOW_SYSTEM
304 305
  if (display_hourglass_p)
    cancel_hourglass ();
306 307
#endif

Jim Blandy's avatar
Jim Blandy committed
308
  debug_on_next_call = 0;
309
  when_entered_debugger = num_nonmacro_input_events;
310 311 312 313 314

  /* 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;
315 316
  specbind (intern ("debugger-may-continue"),
	    debug_while_redisplaying ? Qnil : Qt);
317
  specbind (Qinhibit_redisplay, Qnil);
318
  specbind (Qinhibit_debugger, Qt);
319 320 321

#if 0 /* Binding this prevents execution of Lisp code during
	 redisplay, which necessarily leads to display problems.  */
322
  specbind (Qinhibit_eval_during_redisplay, Qt);
323
#endif
324

325 326 327 328
  val = apply1 (Vdebugger, arg);

  /* Interrupting redisplay and resuming it later is not safe under
     all circumstances.  So, when the debugger returns, abort the
329
     interrupted redisplay by going back to the top-level.  */
330 331 332
  if (debug_while_redisplaying)
    Ftop_level ();

333
  return unbind_to (count, val);
Jim Blandy's avatar
Jim Blandy committed
334 335
}

336
static void
337
do_debug_on_call (Lisp_Object code)
Jim Blandy's avatar
Jim Blandy committed
338 339
{
  debug_on_next_call = 0;
340
  set_backtrace_debug_on_exit (specpdl_ptr - 1, true);
341
  call_debugger (list1 (code));
Jim Blandy's avatar
Jim Blandy committed
342 343 344 345 346 347 348
}

/* 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
349 350 351
       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
352
usage: (or CONDITIONS...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
353
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
354
{
355
  register Lisp_Object val = Qnil;
Jim Blandy's avatar
Jim Blandy committed
356 357
  struct gcpro gcpro1;

358
  GCPRO1 (args);
Jim Blandy's avatar
Jim Blandy committed
359

360
  while (CONSP (args))
Jim Blandy's avatar
Jim Blandy committed
361
    {
362
      val = eval_sub (XCAR (args));
Jim Blandy's avatar
Jim Blandy committed
363
      if (!NILP (val))
Jim Blandy's avatar
Jim Blandy committed
364
	break;
365
      args = XCDR (args);
Jim Blandy's avatar
Jim Blandy committed
366 367 368 369 370 371 372
    }

  UNGCPRO;
  return val;
}

DEFUN ("and", Fand, Sand, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
373
       doc: /* Eval args until one of them yields nil, then return nil.
Pavel Janík's avatar
Pavel Janík committed
374 375
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
376
usage: (and CONDITIONS...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
377
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
378
{
379
  register Lisp_Object val = Qt;
Jim Blandy's avatar
Jim Blandy committed
380 381
  struct gcpro gcpro1;

382
  GCPRO1 (args);
Jim Blandy's avatar
Jim Blandy committed
383

384
  while (CONSP (args))
Jim Blandy's avatar
Jim Blandy committed
385
    {
386
      val = eval_sub (XCAR (args));
Jim Blandy's avatar
Jim Blandy committed
387
      if (NILP (val))
Jim Blandy's avatar
Jim Blandy committed
388
	break;
389
      args = XCDR (args);
Jim Blandy's avatar
Jim Blandy committed
390 391 392 393 394 395 396
    }

  UNGCPRO;
  return val;
}

DEFUN ("if", Fif, Sif, 2, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
397
       doc: /* If COND yields non-nil, do THEN, else do ELSE...
Pavel Janík's avatar
Pavel Janík committed
398 399 400
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.
401
usage: (if COND THEN ELSE...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
402
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
403 404 405 406 407
{
  register Lisp_Object cond;
  struct gcpro gcpro1;

  GCPRO1 (args);
408
  cond = eval_sub (Fcar (args));
Jim Blandy's avatar
Jim Blandy committed
409 410
  UNGCPRO;

Jim Blandy's avatar
Jim Blandy committed
411
  if (!NILP (cond))
412
    return eval_sub (Fcar (Fcdr (args)));
Jim Blandy's avatar
Jim Blandy committed
413 414 415 416
  return Fprogn (Fcdr (Fcdr (args)));
}

DEFUN ("cond", Fcond, Scond, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
417 418 419 420 421 422 423 424
       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.
425
usage: (cond CLAUSES...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
426
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
427 428 429 430 431 432
{
  register Lisp_Object clause, val;
  struct gcpro gcpro1;

  val = Qnil;
  GCPRO1 (args);
Jim Blandy's avatar
Jim Blandy committed
433
  while (!NILP (args))
Jim Blandy's avatar
Jim Blandy committed
434 435
    {
      clause = Fcar (args);
436
      val = eval_sub (Fcar (clause));
Jim Blandy's avatar
Jim Blandy committed
437
      if (!NILP (val))
Jim Blandy's avatar
Jim Blandy committed
438
	{
439 440
	  if (!EQ (XCDR (clause), Qnil))
	    val = Fprogn (XCDR (clause));
Jim Blandy's avatar
Jim Blandy committed
441 442
	  break;
	}
443
      args = XCDR (args);
Jim Blandy's avatar
Jim Blandy committed
444 445 446 447 448 449
    }
  UNGCPRO;

  return val;
}

Paul Eggert's avatar
Paul Eggert committed
450
DEFUN ("progn", Fprogn, Sprogn, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
451
       doc: /* Eval BODY forms sequentially and return value of last one.
Juanma Barranquero's avatar
Juanma Barranquero committed
452
usage: (progn BODY...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
453
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
454
{
455
  register Lisp_Object val = Qnil;
Jim Blandy's avatar
Jim Blandy committed
456 457
  struct gcpro gcpro1;

458
  GCPRO1 (args);
Jim Blandy's avatar
Jim Blandy committed
459

460
  while (CONSP (args))
Jim Blandy's avatar
Jim Blandy committed
461
    {
462
      val = eval_sub (XCAR (args));
463
      args = XCDR (args);
Jim Blandy's avatar
Jim Blandy committed
464 465 466 467 468 469 470
    }

  UNGCPRO;
  return val;
}

DEFUN ("prog1", Fprog1, Sprog1, 1, UNEVALLED, 0,
471
       doc: /* Eval FIRST and BODY sequentially; return value from FIRST.
Pavel Janík's avatar
Pavel Janík committed
472 473
The value of FIRST is saved during the evaluation of the remaining args,
whose values are discarded.
474
usage: (prog1 FIRST BODY...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
475
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
476 477 478 479 480 481 482 483 484
{
  Lisp_Object val;
  register Lisp_Object args_left;
  struct gcpro gcpro1, gcpro2;

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

485 486 487
  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
488 489 490 491 492 493

  UNGCPRO;
  return val;
}

DEFUN ("prog2", Fprog2, Sprog2, 2, UNEVALLED, 0,
494
       doc: /* Eval FORM1, FORM2 and BODY sequentially; return value from FORM2.
495 496 497
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
498
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
499
{
500
  struct gcpro gcpro1;
Jim Blandy's avatar
Jim Blandy committed
501

502 503
  GCPRO1 (args);
  eval_sub (XCAR (args));
504 505
  UNGCPRO;
  return Fprog1 (XCDR (args));
Jim Blandy's avatar
Jim Blandy committed
506 507 508
}

DEFUN ("setq", Fsetq, Ssetq, 0, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
509 510 511 512 513 514 515
       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
516
usage: (setq [SYM VAL]...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
517
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
518 519
{
  register Lisp_Object args_left;
520
  register Lisp_Object val, sym, lex_binding;
Jim Blandy's avatar
Jim Blandy committed
521 522
  struct gcpro gcpro1;

523
  if (NILP (args))
Jim Blandy's avatar
Jim Blandy committed
524 525 526 527 528 529 530
    return Qnil;

  args_left = args;
  GCPRO1 (args);

  do
    {
531
      val = eval_sub (Fcar (Fcdr (args_left)));
Jim Blandy's avatar
Jim Blandy committed
532
      sym = Fcar (args_left);
533

534
      /* Like for eval_sub, we do not check declared_special here since
535 536
	 it's been done when let-binding.  */
      if (!NILP (Vinternal_interpreter_environment) /* Mere optimization!  */
537
	  && SYMBOLP (sym)
538 539
	  && !NILP (lex_binding
		    = Fassq (sym, Vinternal_interpreter_environment)))
540 541 542 543
	XSETCDR (lex_binding, val); /* SYM is lexically bound.  */
      else
	Fset (sym, val);	/* SYM is dynamically bound.  */

Jim Blandy's avatar
Jim Blandy committed
544 545
      args_left = Fcdr (Fcdr (args_left));
    }
Juanma Barranquero's avatar
Juanma Barranquero committed
546
  while (!NILP (args_left));
Jim Blandy's avatar
Jim Blandy committed
547 548 549 550

  UNGCPRO;
  return val;
}
551

Jim Blandy's avatar
Jim Blandy committed
552
DEFUN ("quote", Fquote, Squote, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
553
       doc: /* Return the argument, without evaluating it.  `(quote x)' yields `x'.
554 555 556 557 558 559 560 561
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
562
usage: (quote ARG)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
563
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
564
{
565 566
  if (!NILP (Fcdr (args)))
    xsignal2 (Qwrong_number_of_arguments, Qquote, Flength (args));
Jim Blandy's avatar
Jim Blandy committed
567 568
  return Fcar (args);
}
569

Jim Blandy's avatar
Jim Blandy committed
570
DEFUN ("function", Ffunction, Sfunction, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
571 572 573 574
       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
575
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
576
{
577 578
  Lisp_Object quoted = XCAR (args);

579 580
  if (!NILP (Fcdr (args)))
    xsignal2 (Qwrong_number_of_arguments, Qfunction, Flength (args));
581 582 583 584 585 586

  if (!NILP (Vinternal_interpreter_environment)
      && CONSP (quoted)
      && EQ (XCAR (quoted), Qlambda))
    /* This is a lambda expression within a lexical environment;
       return an interpreted closure instead of a simple lambda.  */
587 588
    return Fcons (Qclosure, Fcons (Vinternal_interpreter_environment,
				   XCDR (quoted)));
589 590 591
  else
    /* Simply quote the argument.  */
    return quoted;
Jim Blandy's avatar
Jim Blandy committed
592 593
}

594

595
DEFUN ("defvaralias", Fdefvaralias, Sdefvaralias, 2, 3, 0,
596
       doc: /* Make NEW-ALIAS a variable alias for symbol BASE-VARIABLE.
Richard M. Stallman's avatar
Richard M. Stallman committed
597
Aliased variables always have the same value; setting one sets the other.
598
Third arg DOCSTRING, if non-nil, is documentation for NEW-ALIAS.  If it is
599 600 601 602
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.
603
The return value is BASE-VARIABLE.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
604
  (Lisp_Object new_alias, Lisp_Object base_variable, Lisp_Object docstring)
Gerd Moellmann's avatar
Gerd Moellmann committed
605 606
{
  struct Lisp_Symbol *sym;
607

608 609
  CHECK_SYMBOL (new_alias);
  CHECK_SYMBOL (base_variable);
Gerd Moellmann's avatar
Gerd Moellmann committed
610

611
  sym = XSYMBOL (new_alias);
612 613

  if (sym->constant)
Stefan Monnier's avatar
Stefan Monnier committed
614 615
    /* Not sure why, but why not?  */
    error ("Cannot make a constant an alias");
616 617 618 619 620 621 622 623 624

  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");
    }

625
  /* http://lists.gnu.org/archive/html/emacs-devel/2008-04/msg00834.html
626 627 628 629
     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)))
630
    set_internal (base_variable, find_symbol_value (new_alias), Qnil, 1);
631 632

  {
633
    union specbinding *p;
634

Paul Eggert's avatar
Paul Eggert committed
635
    for (p = specpdl_ptr; p > specpdl; )
636 637
      if ((--p)->kind >= SPECPDL_LET
	  && (EQ (new_alias, specpdl_symbol (p))))
638 639 640
	error ("Don't know how to make a let-bound variable an alias");
  }

641
  sym->declared_special = 1;
642
  XSYMBOL (base_variable)->declared_special = 1;
643 644
  sym->redirect = SYMBOL_VARALIAS;
  SET_SYMBOL_ALIAS (sym, XSYMBOL (base_variable));
645 646
  sym->constant = SYMBOL_CONSTANT_P (base_variable);
  LOADHIST_ATTACH (new_alias);
647 648
  /* Even if docstring is nil: remove old docstring.  */
  Fput (new_alias, Qvariable_documentation, docstring);
649

650
  return base_variable;
Gerd Moellmann's avatar
Gerd Moellmann committed
651 652 653
}


Jim Blandy's avatar
Jim Blandy committed
654
DEFUN ("defvar", Fdefvar, Sdefvar, 1, UNEVALLED, 0,
Juanma Barranquero's avatar
Juanma Barranquero committed
655
       doc: /* Define SYMBOL as a variable, and return SYMBOL.
656 657 658 659 660 661 662 663 664
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
665
If INITVALUE is missing, SYMBOL's value is not set.
666 667 668 669 670 671 672

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.)
673 674 675 676 677

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

To define a user option, use `defcustom' instead of `defvar'.
678
usage: (defvar SYMBOL &optional INITVALUE DOCSTRING)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
679
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
680
{
681
  register Lisp_Object sym, tem, tail;
Jim Blandy's avatar
Jim Blandy committed
682 683

  sym = Fcar (args);
684 685
  tail = Fcdr (args);
  if (!NILP (Fcdr (Fcdr (tail))))
686
    error ("Too many arguments");
687

688
  tem = Fdefault_boundp (sym);
689
  if (!NILP (tail))
Jim Blandy's avatar
Jim Blandy committed
690
    {
691 692
      /* Do it before evaluating the initial value, for self-references.  */
      XSYMBOL (sym)->declared_special = 1;
693

Jim Blandy's avatar
Jim Blandy committed
694
      if (NILP (tem))
695
	Fset_default (sym, eval_sub (Fcar (tail)));
696 697 698
      else
	{ /* Check if there is really a global binding rather than just a let
	     binding that shadows the global unboundness of the var.  */
699
	  union specbinding *pdl = specpdl_ptr;
700
	  while (pdl > specpdl)
701
	    {
702 703 704
	      if ((--pdl)->kind >= SPECPDL_LET
		  && EQ (specpdl_symbol (pdl), sym)
		  && EQ (specpdl_old_value (pdl), Qunbound))
705
		{
706 707 708
		  message_with_string
		    ("Warning: defvar ignored because %s is let-bound",
		     SYMBOL_NAME (sym), 1);
709 710 711 712
		  break;
		}
	    }
	}
713
      tail = Fcdr (tail);
714 715
      tem = Fcar (tail);
      if (!NILP (tem))
716 717 718 719 720
	{
	  if (!NILP (Vpurify_flag))
	    tem = Fpurecopy (tem);
	  Fput (sym, Qvariable_documentation, tem);
	}
721
      LOADHIST_ATTACH (sym);
Jim Blandy's avatar
Jim Blandy committed
722
    }
723 724 725 726 727
  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).  */
728 729
    Vinternal_interpreter_environment
      = Fcons (sym, Vinternal_interpreter_environment);
730
  else
731 732 733 734 735
    {
      /* 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
736

Jim Blandy's avatar
Jim Blandy committed
737 738 739 740
  return sym;
}

DEFUN ("defconst", Fdefconst, Sdefconst, 2, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
741
       doc: /* Define SYMBOL as a constant variable.
742 743 744 745 746 747 748 749 750 751 752 753 754
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.
755
usage: (defconst SYMBOL INITVALUE [DOCSTRING])  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
756
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
757 758 759 760
{
  register Lisp_Object sym, tem;

  sym = Fcar (args);
761
  if (!NILP (Fcdr (Fcdr (Fcdr (args)))))
762
    error ("Too many arguments");
763

764
  tem = eval_sub (Fcar (Fcdr (args)));
765 766 767
  if (!NILP (Vpurify_flag))
    tem = Fpurecopy (tem);
  Fset_default (sym, tem);
768
  XSYMBOL (sym)->declared_special = 1;
Jim Blandy's avatar
Jim Blandy committed
769
  tem = Fcar (Fcdr (Fcdr (args)));
Jim Blandy's avatar
Jim Blandy committed
770
  if (!NILP (tem))
Jim Blandy's avatar
Jim Blandy committed
771
    {
Jim Blandy's avatar
Jim Blandy committed
772
      if (!NILP (Vpurify_flag))
Jim Blandy's avatar
Jim Blandy committed
773 774 775
	tem = Fpurecopy (tem);
      Fput (sym, Qvariable_documentation, tem);
    }
776
  Fput (sym, Qrisky_local_variable, Qt);
777
  LOADHIST_ATTACH (sym);
Jim Blandy's avatar
Jim Blandy committed
778 779 780
  return sym;
}

781 782 783 784 785 786 787 788 789 790 791
/* 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
792 793

DEFUN ("let*", FletX, SletX, 1, UNEVALLED, 0,
Pavel Janík's avatar
Pavel Janík committed
794 795 796 797 798
       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.
799
usage: (let* VARLIST BODY...)  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
800
  (Lisp_Object args)
Jim Blandy's avatar
Jim Blandy committed
801
{
802
  Lisp_Object varlist, var, val, elt, lexenv;
803
  ptrdiff_t count = SPECPDL_INDEX ();
Jim Blandy's avatar
Jim Blandy committed
804 805 806 807
  struct gcpro gcpro1, gcpro2, gcpro3;

  GCPRO3 (args, elt, varlist);

808 809
  lexenv = Vinternal_interpreter_environment;

Jim Blandy's avatar
Jim Blandy committed
810
  varlist = Fcar (args);
811
  while (CONSP (varlist))
Jim Blandy's avatar
Jim Blandy committed
812 813
    {
      QUIT;
814 815

      elt = XCAR (varlist);
816
      if (SYMBOLP (elt))