This allows calling a function whenever a symbol-value is changed.
* src/lisp.h (lisp_h_SYMBOL_TRAPPED_WRITE_P):
(SYMBOL_TRAPPED_WRITE_P): New function/macro.
(lisp_h_SYMBOL_CONSTANT_P): Check for SYMBOL_NOWRITE specifically.
(enum symbol_trapped_write): New enumeration.
(struct Lisp_Symbol): Rename field constant to trapped_write.
(make_symbol_constant): New function.
* src/data.c (Fadd_variable_watcher, Fremove_variable_watcher):
(set_symbol_trapped_write, restore_symbol_trapped_write):
(harmonize_variable_watchers, notify_variable_watchers): New functions.
* src/data.c (Fset_default): Call `notify_variable_watchers' for trapped
symbols.
(set_internal): Change bool argument BIND to 3-value enum and call
`notify_variable_watchers' for trapped symbols.
* src/data.c (syms_of_data):
* src/data.c (syms_of_data):
* src/font.c (syms_of_font):
* src/lread.c (intern_sym, init_obarray):
* src/buffer.c (syms_of_buffer): Use make_symbol_constant.
* src/alloc.c (init_symbol):
* src/bytecode.c (exec_byte_code): Use SYMBOL_TRAPPED_WRITE_P.
* src/data.c (Fmake_variable_buffer_local, Fmake_local_variable):
(Fmake_variable_frame_local):
* src/eval.c (Fdefvaralias, specbind): Refer to Lisp_Symbol's
trapped_write instead of constant.
(Ffuncall): Move subr calling code into separate function.
(funcall_subr): New function.
set_symbol_next (val, NULL);
p->gcmarkbit = false;
p->interned = SYMBOL_UNINTERNED;
- p->constant = 0;
+ p->trapped_write = SYMBOL_UNTRAPPED_WRITE;
p->declared_special = false;
p->pinned = false;
}
bset_local_var_alist (b, Qnil);
else
{
- Lisp_Object tmp, prop, last = Qnil;
+ Lisp_Object tmp, last = Qnil;
for (tmp = BVAR (b, local_var_alist); CONSP (tmp); tmp = XCDR (tmp))
- if (!NILP (prop = Fget (XCAR (XCAR (tmp)), Qpermanent_local)))
- {
- /* If permanent-local, keep it. */
- last = tmp;
- if (EQ (prop, Qpermanent_local_hook))
- {
- /* This is a partially permanent hook variable.
- Preserve only the elements that want to be preserved. */
- Lisp_Object list, newlist;
- list = XCDR (XCAR (tmp));
- if (!CONSP (list))
- newlist = list;
- else
- for (newlist = Qnil; CONSP (list); list = XCDR (list))
- {
- Lisp_Object elt = XCAR (list);
- /* Preserve element ELT if it's t,
- if it is a function with a `permanent-local-hook' property,
- or if it's not a symbol. */
- if (! SYMBOLP (elt)
- || EQ (elt, Qt)
- || !NILP (Fget (elt, Qpermanent_local_hook)))
- newlist = Fcons (elt, newlist);
- }
- XSETCDR (XCAR (tmp), Fnreverse (newlist));
- }
- }
- /* Delete this local variable. */
- else if (NILP (last))
- bset_local_var_alist (b, XCDR (tmp));
- else
- XSETCDR (last, XCDR (tmp));
+ {
+ Lisp_Object local_var = XCAR (XCAR (tmp));
+ Lisp_Object prop = Fget (local_var, Qpermanent_local);
+
+ if (!NILP (prop))
+ {
+ /* If permanent-local, keep it. */
+ last = tmp;
+ if (EQ (prop, Qpermanent_local_hook))
+ {
+ /* This is a partially permanent hook variable.
+ Preserve only the elements that want to be preserved. */
+ Lisp_Object list, newlist;
+ list = XCDR (XCAR (tmp));
+ if (!CONSP (list))
+ newlist = list;
+ else
+ for (newlist = Qnil; CONSP (list); list = XCDR (list))
+ {
+ Lisp_Object elt = XCAR (list);
+ /* Preserve element ELT if it's t,
+ if it is a function with a `permanent-local-hook' property,
+ or if it's not a symbol. */
+ if (! SYMBOLP (elt)
+ || EQ (elt, Qt)
+ || !NILP (Fget (elt, Qpermanent_local_hook)))
+ newlist = Fcons (elt, newlist);
+ }
+ newlist = Fnreverse (newlist);
+ if (XSYMBOL (local_var)->trapped_write == SYMBOL_TRAPPED_WRITE)
+ notify_variable_watchers (local_var, newlist,
+ Qmakunbound, Fcurrent_buffer ());
+ XSETCDR (XCAR (tmp), newlist);
+ continue; /* Don't do variable write trapping twice. */
+ }
+ }
+ /* Delete this local variable. */
+ else if (NILP (last))
+ bset_local_var_alist (b, XCDR (tmp));
+ else
+ XSETCDR (last, XCDR (tmp));
+
+ if (XSYMBOL (local_var)->trapped_write == SYMBOL_TRAPPED_WRITE)
+ notify_variable_watchers (local_var, Qnil,
+ Qmakunbound, Fcurrent_buffer ());
+ }
}
for (i = 0; i < last_per_buffer_idx; ++i)
This variable is buffer-local but you cannot set it directly;
use the function `set-buffer-multibyte' to change a buffer's representation.
See also Info node `(elisp)Text Representations'. */);
- XSYMBOL (intern_c_string ("enable-multibyte-characters"))->constant = 1;
+ make_symbol_constant (intern_c_string ("enable-multibyte-characters"));
DEFVAR_PER_BUFFER ("buffer-file-coding-system",
&BVAR (current_buffer, buffer_file_coding_system), Qnil,
if (SYMBOLP (sym)
&& !EQ (val, Qunbound)
&& !XSYMBOL (sym)->redirect
- && !SYMBOL_CONSTANT_P (sym))
+ && !SYMBOL_TRAPPED_WRITE_P (sym))
SET_SYMBOL_VAL (XSYMBOL (sym), val);
else
- set_internal (sym, val, Qnil, false);
+ set_internal (sym, val, Qnil, SET_INTERNAL_SET);
}
NEXT;
doc: /* Set SYMBOL's value to NEWVAL, and return NEWVAL. */)
(register Lisp_Object symbol, Lisp_Object newval)
{
- set_internal (symbol, newval, Qnil, 0);
+ set_internal (symbol, newval, Qnil, SET_INTERNAL_SET);
return newval;
}
If buffer/frame-locality is an issue, WHERE specifies which context to use.
(nil stands for the current buffer/frame).
- If BINDFLAG is false, then if this symbol is supposed to become
- local in every buffer where it is set, then we make it local.
- If BINDFLAG is true, we don't do that. */
+ If BINDFLAG is SET_INTERNAL_SET, then if this symbol is supposed to
+ become local in every buffer where it is set, then we make it
+ local. If BINDFLAG is SET_INTERNAL_BIND or SET_INTERNAL_UNBIND, we
+ don't do that. */
void
set_internal (Lisp_Object symbol, Lisp_Object newval, Lisp_Object where,
- bool bindflag)
+ enum Set_Internal_Bind bindflag)
{
bool voide = EQ (newval, Qunbound);
struct Lisp_Symbol *sym;
return; */
CHECK_SYMBOL (symbol);
- if (SYMBOL_CONSTANT_P (symbol))
+ sym = XSYMBOL (symbol);
+ switch (sym->trapped_write)
{
+ case SYMBOL_NOWRITE:
if (NILP (Fkeywordp (symbol))
- || !EQ (newval, Fsymbol_value (symbol)))
- xsignal1 (Qsetting_constant, symbol);
+ || !EQ (newval, Fsymbol_value (symbol)))
+ xsignal1 (Qsetting_constant, symbol);
else
- /* Allow setting keywords to their own value. */
- return;
+ /* Allow setting keywords to their own value. */
+ return;
+
+ case SYMBOL_TRAPPED_WRITE:
+ notify_variable_watchers (symbol, voide? Qnil : newval,
+ (bindflag == SET_INTERNAL_BIND? Qlet :
+ bindflag == SET_INTERNAL_UNBIND? Qunlet :
+ voide? Qmakunbound : Qset),
+ where);
+ /* FALLTHROUGH! */
+ case SYMBOL_UNTRAPPED_WRITE:
+ break;
+
+ default: emacs_abort ();
}
maybe_set_redisplay (symbol);
- sym = XSYMBOL (symbol);
start:
switch (sym->redirect)
}
return;
}
+
+static void
+set_symbol_trapped_write (Lisp_Object symbol, enum symbol_trapped_write trap)
+{
+ struct Lisp_Symbol* sym = XSYMBOL (symbol);
+ if (sym->trapped_write == SYMBOL_NOWRITE)
+ xsignal1 (Qtrapping_constant, symbol);
+ else if (sym->redirect == SYMBOL_LOCALIZED
+ && SYMBOL_BLV (sym)->frame_local)
+ xsignal1 (Qtrapping_frame_local, symbol);
+ sym->trapped_write = trap;
+}
+
+static void
+restore_symbol_trapped_write (Lisp_Object symbol)
+{
+ set_symbol_trapped_write (symbol, SYMBOL_TRAPPED_WRITE);
+}
+
+static void
+harmonize_variable_watchers (Lisp_Object alias, Lisp_Object base_variable)
+{
+ if (!EQ (base_variable, alias)
+ && EQ (base_variable, Findirect_variable (alias)))
+ set_symbol_trapped_write
+ (alias, XSYMBOL (base_variable)->trapped_write);
+}
+
+DEFUN ("add-variable-watcher", Fadd_variable_watcher, Sadd_variable_watcher,
+ 2, 2, 0,
+ doc: /* Cause WATCH-FUNCTION to be called when SYMBOL is set.
+All writes to aliases of SYMBOL will call WATCH-FUNCTION too. */)
+ (Lisp_Object symbol, Lisp_Object watch_function)
+{
+ symbol = Findirect_variable (symbol);
+ set_symbol_trapped_write (symbol, SYMBOL_TRAPPED_WRITE);
+ map_obarray (Vobarray, harmonize_variable_watchers, symbol);
+
+ Lisp_Object watchers = Fget (symbol, Qwatchers);
+ Lisp_Object member = Fmember (watch_function, watchers);
+ if (NILP (member))
+ Fput (symbol, Qwatchers, Fcons (watch_function, watchers));
+ return Qnil;
+}
+
+DEFUN ("remove-variable-watcher", Fremove_variable_watcher, Sremove_variable_watcher,
+ 2, 2, 0,
+ doc: /* Undo the effect of `add-variable-watcher'.
+Remove WATCH-FUNCTION from the list of functions to be called when
+SYMBOL (or its aliases) are set. */)
+ (Lisp_Object symbol, Lisp_Object watch_function)
+{
+ symbol = Findirect_variable (symbol);
+ Lisp_Object watchers = Fget (symbol, Qwatchers);
+ watchers = Fdelete (watch_function, watchers);
+ if (NILP (watchers))
+ {
+ set_symbol_trapped_write (symbol, SYMBOL_UNTRAPPED_WRITE);
+ map_obarray (Vobarray, harmonize_variable_watchers, symbol);
+ }
+ Fput (symbol, Qwatchers, watchers);
+ return Qnil;
+}
+
+void
+notify_variable_watchers (Lisp_Object symbol,
+ Lisp_Object newval,
+ Lisp_Object operation,
+ Lisp_Object where)
+{
+ symbol = Findirect_variable (symbol);
+
+ ptrdiff_t count = SPECPDL_INDEX ();
+ record_unwind_protect (restore_symbol_trapped_write, symbol);
+ /* Avoid recursion. */
+ set_symbol_trapped_write (symbol, SYMBOL_UNTRAPPED_WRITE);
+
+ if (NILP (where)
+ && !EQ (operation, Qset_default) && !EQ (operation, Qmakunbound)
+ && !NILP (Flocal_variable_if_set_p (symbol, Fcurrent_buffer ())))
+ {
+ XSETBUFFER (where, current_buffer);
+ }
+
+ if (EQ (operation, Qset_default))
+ operation = Qset;
+
+ for (Lisp_Object watchers = Fget (symbol, Qwatchers);
+ CONSP (watchers);
+ watchers = XCDR (watchers))
+ {
+ Lisp_Object watcher = XCAR (watchers);
+ /* Call subr directly to avoid gc. */
+ if (SUBRP (watcher))
+ {
+ Lisp_Object args[] = { symbol, newval, operation, where };
+ funcall_subr (XSUBR (watcher), ARRAYELTS (args), args);
+ }
+ else
+ CALLN (Ffuncall, watcher, symbol, newval, operation, where);
+ }
+
+ unbind_to (count, Qnil);
+}
+
\f
/* Access or set a buffer-local symbol's default value. */
struct Lisp_Symbol *sym;
CHECK_SYMBOL (symbol);
- if (SYMBOL_CONSTANT_P (symbol))
+ sym = XSYMBOL (symbol);
+ switch (sym->trapped_write)
{
+ case SYMBOL_NOWRITE:
if (NILP (Fkeywordp (symbol))
- || !EQ (value, Fdefault_value (symbol)))
- xsignal1 (Qsetting_constant, symbol);
+ || !EQ (value, Fsymbol_value (symbol)))
+ xsignal1 (Qsetting_constant, symbol);
else
- /* Allow setting keywords to their own value. */
- return value;
+ /* Allow setting keywords to their own value. */
+ return value;
+
+ case SYMBOL_TRAPPED_WRITE:
+ /* Don't notify here if we're going to call Fset anyway. */
+ if (sym->redirect != SYMBOL_PLAINVAL)
+ notify_variable_watchers (symbol, value, Qset_default, Qnil);
+ /* FALLTHROUGH! */
+ case SYMBOL_UNTRAPPED_WRITE:
+ break;
+
+ default: emacs_abort ();
}
- sym = XSYMBOL (symbol);
start:
switch (sym->redirect)
default: emacs_abort ();
}
- if (sym->constant)
+ if (SYMBOL_CONSTANT_P (variable))
error ("Symbol %s may not be buffer-local", SDATA (SYMBOL_NAME (variable)));
if (!blv)
default: emacs_abort ();
}
- if (sym->constant)
+ if (sym->trapped_write == SYMBOL_NOWRITE)
error ("Symbol %s may not be buffer-local",
SDATA (SYMBOL_NAME (variable)));
default: emacs_abort ();
}
+ if (sym->trapped_write == SYMBOL_TRAPPED_WRITE)
+ notify_variable_watchers (variable, Qnil, Qmakunbound, Fcurrent_buffer ());
+
/* Get rid of this buffer's alist element, if any. */
XSETSYMBOL (variable, sym); /* Propagate variable indirection. */
tem = Fassq (variable, BVAR (current_buffer, local_var_alist));
default: emacs_abort ();
}
- if (sym->constant)
+ if (SYMBOL_TRAPPED_WRITE_P (variable))
error ("Symbol %s may not be frame-local", SDATA (SYMBOL_NAME (variable)));
blv = make_blv (sym, forwarded, valcontents);
DEFSYM (Qcyclic_variable_indirection, "cyclic-variable-indirection");
DEFSYM (Qvoid_variable, "void-variable");
DEFSYM (Qsetting_constant, "setting-constant");
+ DEFSYM (Qtrapping_constant, "trapping-constant");
+ DEFSYM (Qtrapping_frame_local, "trapping-frame-local");
DEFSYM (Qinvalid_read_syntax, "invalid-read-syntax");
DEFSYM (Qinvalid_function, "invalid-function");
PUT_ERROR (Qvoid_variable, error_tail, "Symbol's value as variable is void");
PUT_ERROR (Qsetting_constant, error_tail,
"Attempt to set a constant symbol");
+ PUT_ERROR (Qtrapping_constant, error_tail,
+ "Attempt to trap writes to a constant symbol");
+ PUT_ERROR (Qtrapping_frame_local, error_tail,
+ "Attempt to trap writes to a frame local variable");
PUT_ERROR (Qinvalid_read_syntax, error_tail, "Invalid read syntax");
PUT_ERROR (Qinvalid_function, error_tail, "Invalid function");
PUT_ERROR (Qwrong_number_of_arguments, error_tail,
DEFVAR_LISP ("most-positive-fixnum", Vmost_positive_fixnum,
doc: /* The largest value that is representable in a Lisp integer. */);
Vmost_positive_fixnum = make_number (MOST_POSITIVE_FIXNUM);
- XSYMBOL (intern_c_string ("most-positive-fixnum"))->constant = 1;
+ make_symbol_constant (intern_c_string ("most-positive-fixnum"));
DEFVAR_LISP ("most-negative-fixnum", Vmost_negative_fixnum,
doc: /* The smallest value that is representable in a Lisp integer. */);
Vmost_negative_fixnum = make_number (MOST_NEGATIVE_FIXNUM);
- XSYMBOL (intern_c_string ("most-negative-fixnum"))->constant = 1;
+ make_symbol_constant (intern_c_string ("most-negative-fixnum"));
+
+ DEFSYM (Qwatchers, "watchers");
+ DEFSYM (Qmakunbound, "makunbound");
+ DEFSYM (Qunlet, "unlet");
+ DEFSYM (Qset, "set");
+ DEFSYM (Qset_default, "set-default");
+ defsubr (&Sadd_variable_watcher);
+ defsubr (&Sremove_variable_watcher);
}
CHECK_SYMBOL (new_alias);
CHECK_SYMBOL (base_variable);
- sym = XSYMBOL (new_alias);
-
- if (sym->constant)
- /* Not sure why, but why not? */
+ if (SYMBOL_CONSTANT_P (new_alias))
+ /* Making it an alias effectively changes its value. */
error ("Cannot make a constant an alias");
+ sym = XSYMBOL (new_alias);
+
switch (sym->redirect)
{
case SYMBOL_FORWARDED:
so that old-code that affects n_a before the aliasing is setup
still works. */
if (NILP (Fboundp (base_variable)))
- set_internal (base_variable, find_symbol_value (new_alias), Qnil, 1);
-
+ set_internal (base_variable, find_symbol_value (new_alias),
+ Qnil, SET_INTERNAL_BIND);
{
union specbinding *p;
error ("Don't know how to make a let-bound variable an alias");
}
+ if (sym->trapped_write == SYMBOL_TRAPPED_WRITE)
+ notify_variable_watchers (new_alias, base_variable, Qdefvaralias, Qnil);
+
sym->declared_special = 1;
XSYMBOL (base_variable)->declared_special = 1;
sym->redirect = SYMBOL_VARALIAS;
SET_SYMBOL_ALIAS (sym, XSYMBOL (base_variable));
- sym->constant = SYMBOL_CONSTANT_P (base_variable);
+ sym->trapped_write = XSYMBOL (base_variable)->trapped_write;
LOADHIST_ATTACH (new_alias);
/* Even if docstring is nil: remove old docstring. */
Fput (new_alias, Qvariable_documentation, docstring);
Lisp_Object fun, original_fun;
Lisp_Object funcar;
ptrdiff_t numargs = nargs - 1;
- Lisp_Object lisp_numargs;
Lisp_Object val;
- Lisp_Object *internal_args;
ptrdiff_t count;
QUIT;
fun = indirect_function (fun);
if (SUBRP (fun))
- {
- if (numargs < XSUBR (fun)->min_args
- || (XSUBR (fun)->max_args >= 0 && XSUBR (fun)->max_args < numargs))
- {
- XSETFASTINT (lisp_numargs, numargs);
- xsignal2 (Qwrong_number_of_arguments, original_fun, lisp_numargs);
- }
-
- else if (XSUBR (fun)->max_args == UNEVALLED)
- xsignal1 (Qinvalid_function, original_fun);
-
- else if (XSUBR (fun)->max_args == MANY)
- val = (XSUBR (fun)->function.aMANY) (numargs, args + 1);
- else
- {
- Lisp_Object internal_argbuf[8];
- if (XSUBR (fun)->max_args > numargs)
- {
- eassert (XSUBR (fun)->max_args <= ARRAYELTS (internal_argbuf));
- internal_args = internal_argbuf;
- memcpy (internal_args, args + 1, numargs * word_size);
- memclear (internal_args + numargs,
- (XSUBR (fun)->max_args - numargs) * word_size);
- }
- else
- internal_args = args + 1;
- switch (XSUBR (fun)->max_args)
- {
- case 0:
- val = (XSUBR (fun)->function.a0 ());
- break;
- case 1:
- val = (XSUBR (fun)->function.a1 (internal_args[0]));
- break;
- case 2:
- val = (XSUBR (fun)->function.a2
- (internal_args[0], internal_args[1]));
- break;
- case 3:
- val = (XSUBR (fun)->function.a3
- (internal_args[0], internal_args[1], internal_args[2]));
- break;
- case 4:
- val = (XSUBR (fun)->function.a4
- (internal_args[0], internal_args[1], internal_args[2],
- internal_args[3]));
- break;
- case 5:
- val = (XSUBR (fun)->function.a5
- (internal_args[0], internal_args[1], internal_args[2],
- internal_args[3], internal_args[4]));
- break;
- case 6:
- val = (XSUBR (fun)->function.a6
- (internal_args[0], internal_args[1], internal_args[2],
- internal_args[3], internal_args[4], internal_args[5]));
- break;
- case 7:
- val = (XSUBR (fun)->function.a7
- (internal_args[0], internal_args[1], internal_args[2],
- internal_args[3], internal_args[4], internal_args[5],
- internal_args[6]));
- break;
-
- case 8:
- val = (XSUBR (fun)->function.a8
- (internal_args[0], internal_args[1], internal_args[2],
- internal_args[3], internal_args[4], internal_args[5],
- internal_args[6], internal_args[7]));
- break;
-
- default:
-
- /* If a subr takes more than 8 arguments without using MANY
- or UNEVALLED, we need to extend this function to support it.
- Until this is done, there is no way to call the function. */
- emacs_abort ();
- }
- }
- }
+ val = funcall_subr (XSUBR (fun), numargs, args + 1);
else if (COMPILEDP (fun))
val = funcall_lambda (fun, numargs, args + 1);
else
return val;
}
\f
+
+/* Apply a C subroutine SUBR to the NUMARGS evaluated arguments in ARG_VECTOR
+ and return the result of evaluation. */
+
+Lisp_Object
+funcall_subr (struct Lisp_Subr *subr, ptrdiff_t numargs, Lisp_Object *args)
+{
+ if (numargs < subr->min_args
+ || (subr->max_args >= 0 && subr->max_args < numargs))
+ {
+ Lisp_Object fun;
+ XSETSUBR (fun, subr);
+ xsignal2 (Qwrong_number_of_arguments, fun, make_number (numargs));
+ }
+
+ else if (subr->max_args == UNEVALLED)
+ {
+ Lisp_Object fun;
+ XSETSUBR (fun, subr);
+ xsignal1 (Qinvalid_function, fun);
+ }
+
+ else if (subr->max_args == MANY)
+ return (subr->function.aMANY) (numargs, args);
+ else
+ {
+ Lisp_Object internal_argbuf[8];
+ Lisp_Object *internal_args;
+ if (subr->max_args > numargs)
+ {
+ eassert (subr->max_args <= ARRAYELTS (internal_argbuf));
+ internal_args = internal_argbuf;
+ memcpy (internal_args, args, numargs * word_size);
+ memclear (internal_args + numargs,
+ (subr->max_args - numargs) * word_size);
+ }
+ else
+ internal_args = args;
+ switch (subr->max_args)
+ {
+ case 0:
+ return (subr->function.a0 ());
+ case 1:
+ return (subr->function.a1 (internal_args[0]));
+ case 2:
+ return (subr->function.a2
+ (internal_args[0], internal_args[1]));
+ case 3:
+ return (subr->function.a3
+ (internal_args[0], internal_args[1], internal_args[2]));
+ case 4:
+ return (subr->function.a4
+ (internal_args[0], internal_args[1], internal_args[2],
+ internal_args[3]));
+ case 5:
+ return (subr->function.a5
+ (internal_args[0], internal_args[1], internal_args[2],
+ internal_args[3], internal_args[4]));
+ case 6:
+ return (subr->function.a6
+ (internal_args[0], internal_args[1], internal_args[2],
+ internal_args[3], internal_args[4], internal_args[5]));
+ case 7:
+ return (subr->function.a7
+ (internal_args[0], internal_args[1], internal_args[2],
+ internal_args[3], internal_args[4], internal_args[5],
+ internal_args[6]));
+ case 8:
+ return (subr->function.a8
+ (internal_args[0], internal_args[1], internal_args[2],
+ internal_args[3], internal_args[4], internal_args[5],
+ internal_args[6], internal_args[7]));
+
+ default:
+
+ /* If a subr takes more than 8 arguments without using MANY
+ or UNEVALLED, we need to extend this function to support it.
+ Until this is done, there is no way to call the function. */
+ emacs_abort ();
+ }
+ }
+}
+
static Lisp_Object
apply_lambda (Lisp_Object fun, Lisp_Object args, ptrdiff_t count)
{
specpdl_ptr->let.symbol = symbol;
specpdl_ptr->let.old_value = SYMBOL_VAL (sym);
grow_specpdl ();
- if (!sym->constant)
+ if (!sym->trapped_write)
SET_SYMBOL_VAL (sym, value);
else
- set_internal (symbol, value, Qnil, 1);
+ set_internal (symbol, value, Qnil, SET_INTERNAL_BIND);
break;
case SYMBOL_LOCALIZED:
if (SYMBOL_BLV (sym)->frame_local)
specpdl_ptr->let.kind = SPECPDL_LET;
grow_specpdl ();
- set_internal (symbol, value, Qnil, 1);
+ set_internal (symbol, value, Qnil, SET_INTERNAL_BIND);
break;
}
default: emacs_abort ();
case SPECPDL_BACKTRACE:
break;
case SPECPDL_LET:
- { /* If variable has a trivial value (no forwarding), we can
- just set it. No need to check for constant symbols here,
- since that was already done by specbind. */
+ { /* If variable has a trivial value (no forwarding), and
+ isn't trapped, we can just set it. */
Lisp_Object sym = specpdl_symbol (specpdl_ptr);
if (SYMBOLP (sym) && XSYMBOL (sym)->redirect == SYMBOL_PLAINVAL)
{
- SET_SYMBOL_VAL (XSYMBOL (sym),
- specpdl_old_value (specpdl_ptr));
+ if (XSYMBOL (sym)->trapped_write == SYMBOL_UNTRAPPED_WRITE)
+ SET_SYMBOL_VAL (XSYMBOL (sym), specpdl_old_value (specpdl_ptr));
+ else
+ set_internal (sym, specpdl_old_value (specpdl_ptr),
+ Qnil, SET_INTERNAL_UNBIND);
break;
}
else
/* If this was a local binding, reset the value in the appropriate
buffer, but only if that buffer's binding still exists. */
if (!NILP (Flocal_variable_p (symbol, where)))
- set_internal (symbol, old_value, where, 1);
+ set_internal (symbol, old_value, where, SET_INTERNAL_UNBIND);
}
break;
}
{
set_specpdl_old_value
(tmp, Fbuffer_local_value (symbol, where));
- set_internal (symbol, old_value, where, 1);
+ set_internal (symbol, old_value, where, SET_INTERNAL_UNBIND);
}
}
break;
defsubr (&Sset_default_toplevel_value);
defsubr (&Sdefvar);
defsubr (&Sdefvaralias);
+ DEFSYM (Qdefvaralias, "defvaralias");
defsubr (&Sdefconst);
defsubr (&Smake_var_non_special);
defsubr (&Slet);
[NUMERIC-VALUE SYMBOLIC-NAME ALIAS-NAME ...]
NUMERIC-VALUE is an integer, and SYMBOLIC-NAME and ALIAS-NAME are symbols. */);
Vfont_weight_table = BUILD_STYLE_TABLE (weight_table);
- XSYMBOL (intern_c_string ("font-weight-table"))->constant = 1;
+ make_symbol_constant (intern_c_string ("font-weight-table"));
DEFVAR_LISP_NOPRO ("font-slant-table", Vfont_slant_table,
doc: /* Vector of font slant symbols vs the corresponding numeric values.
See `font-weight-table' for the format of the vector. */);
Vfont_slant_table = BUILD_STYLE_TABLE (slant_table);
- XSYMBOL (intern_c_string ("font-slant-table"))->constant = 1;
+ make_symbol_constant (intern_c_string ("font-slant-table"));
DEFVAR_LISP_NOPRO ("font-width-table", Vfont_width_table,
doc: /* Alist of font width symbols vs the corresponding numeric values.
See `font-weight-table' for the format of the vector. */);
Vfont_width_table = BUILD_STYLE_TABLE (width_table);
- XSYMBOL (intern_c_string ("font-width-table"))->constant = 1;
+ make_symbol_constant (intern_c_string ("font-width-table"));
staticpro (&font_style_table);
font_style_table = make_uninit_vector (3);
#define lisp_h_NILP(x) EQ (x, Qnil)
#define lisp_h_SET_SYMBOL_VAL(sym, v) \
(eassert ((sym)->redirect == SYMBOL_PLAINVAL), (sym)->val.value = (v))
-#define lisp_h_SYMBOL_CONSTANT_P(sym) (XSYMBOL (sym)->constant)
+#define lisp_h_SYMBOL_CONSTANT_P(sym) (XSYMBOL (sym)->trapped_write == SYMBOL_NOWRITE)
+#define lisp_h_SYMBOL_TRAPPED_WRITE_P(sym) (XSYMBOL (sym)->trapped_write)
#define lisp_h_SYMBOL_VAL(sym) \
(eassert ((sym)->redirect == SYMBOL_PLAINVAL), (sym)->val.value)
#define lisp_h_SYMBOLP(x) (XTYPE (x) == Lisp_Symbol)
# define NILP(x) lisp_h_NILP (x)
# define SET_SYMBOL_VAL(sym, v) lisp_h_SET_SYMBOL_VAL (sym, v)
# define SYMBOL_CONSTANT_P(sym) lisp_h_SYMBOL_CONSTANT_P (sym)
+# define SYMBOL_TRAPPED_WRITE_P(sym) lisp_h_SYMBOL_TRAPPED_WRITE_P (sym)
# define SYMBOL_VAL(sym) lisp_h_SYMBOL_VAL (sym)
# define SYMBOLP(x) lisp_h_SYMBOLP (x)
# define VECTORLIKEP(x) lisp_h_VECTORLIKEP (x)
/* Defined in data.c. */
extern _Noreturn Lisp_Object wrong_type_argument (Lisp_Object, Lisp_Object);
extern _Noreturn void wrong_choice (Lisp_Object, Lisp_Object);
+extern void notify_variable_watchers (Lisp_Object symbol, Lisp_Object newval,
+ Lisp_Object operation, Lisp_Object where);
+
#ifdef CANNOT_DUMP
enum { might_dump = false };
SYMBOL_FORWARDED = 3
};
+enum symbol_trapped_write
+{
+ SYMBOL_UNTRAPPED_WRITE = 0,
+ SYMBOL_NOWRITE = 1,
+ SYMBOL_TRAPPED_WRITE = 2
+};
+
struct Lisp_Symbol
{
bool_bf gcmarkbit : 1;
3 : it's a forwarding variable, the value is in `forward'. */
ENUM_BF (symbol_redirect) redirect : 3;
- /* Non-zero means symbol is constant, i.e. changing its value
- should signal an error. If the value is 3, then the var
- can be changed, but only by `defconst'. */
- unsigned constant : 2;
+ /* 0 : normal case, just set the value
+ 1 : constant, cannot set, e.g. nil, t, :keywords.
+ 2 : trap the write, call watcher functions. */
+ ENUM_BF (symbol_trapped_write) trapped_write : 2;
/* Interned state of the symbol. This is an enumerator from
enum symbol_interned. */
return XSYMBOL (sym)->interned == SYMBOL_INTERNED_IN_INITIAL_OBARRAY;
}
-/* Value is non-zero if symbol is considered a constant, i.e. its
- value cannot be changed (there is an exception for keyword symbols,
- whose value can be set to the keyword symbol itself). */
+/* Value is non-zero if symbol cannot be changed through a simple set,
+ i.e. it's a constant (e.g. nil, t, :keywords), or it has some
+ watching functions. */
+
+INLINE int
+(SYMBOL_TRAPPED_WRITE_P) (Lisp_Object sym)
+{
+ return lisp_h_SYMBOL_TRAPPED_WRITE_P (sym);
+}
+
+/* Value is non-zero if symbol cannot be changed at all, i.e. it's a
+ constant (e.g. nil, t, :keywords). Code that actually wants to
+ write to SYM, should also check whether there are any watching
+ functions. */
INLINE int
(SYMBOL_CONSTANT_P) (Lisp_Object sym)
XSYMBOL (sym)->next = next;
}
+INLINE void
+make_symbol_constant (Lisp_Object sym)
+{
+ XSYMBOL (sym)->trapped_write = SYMBOL_NOWRITE;
+}
+
/* Buffer-local (also frame-local) variable access functions. */
INLINE int
extern _Noreturn void args_out_of_range_3 (Lisp_Object, Lisp_Object,
Lisp_Object);
extern Lisp_Object do_symval_forwarding (union Lisp_Fwd *);
-extern void set_internal (Lisp_Object, Lisp_Object, Lisp_Object, bool);
+enum Set_Internal_Bind {
+ SET_INTERNAL_SET,
+ SET_INTERNAL_BIND,
+ SET_INTERNAL_UNBIND
+};
+extern void set_internal (Lisp_Object, Lisp_Object, Lisp_Object,
+ enum Set_Internal_Bind);
extern void syms_of_data (void);
extern void swap_in_global_binding (struct Lisp_Symbol *);
extern _Noreturn void xsignal3 (Lisp_Object, Lisp_Object, Lisp_Object,
Lisp_Object);
extern _Noreturn void signal_error (const char *, Lisp_Object);
+extern Lisp_Object funcall_subr (struct Lisp_Subr *subr, ptrdiff_t numargs, Lisp_Object *arg_vector);
extern Lisp_Object eval_sub (Lisp_Object form);
extern Lisp_Object apply1 (Lisp_Object, Lisp_Object);
extern Lisp_Object call0 (Lisp_Object);
if (SREF (SYMBOL_NAME (sym), 0) == ':' && EQ (obarray, initial_obarray))
{
- XSYMBOL (sym)->constant = 1;
+ make_symbol_constant (sym);
XSYMBOL (sym)->redirect = SYMBOL_PLAINVAL;
SET_SYMBOL_VAL (XSYMBOL (sym), sym);
}
DEFSYM (Qnil, "nil");
SET_SYMBOL_VAL (XSYMBOL (Qnil), Qnil);
- XSYMBOL (Qnil)->constant = 1;
+ make_symbol_constant (Qnil);
XSYMBOL (Qnil)->declared_special = true;
DEFSYM (Qt, "t");
SET_SYMBOL_VAL (XSYMBOL (Qt), Qt);
- XSYMBOL (Qt)->constant = 1;
+ make_symbol_constant (Qt);
XSYMBOL (Qt)->declared_special = true;
/* Qt is correct even if CANNOT_DUMP. loadup.el will set to nil at end. */
projects / emacs.git / commitdiff