return pdl->let.old_value;
}
+static void
+set_specpdl_old_value (union specbinding *pdl, Lisp_Object val)
+{
+ eassert (pdl->kind >= SPECPDL_LET);
+ pdl->let.old_value = val;
+}
+
static Lisp_Object
specpdl_where (union specbinding *pdl)
{
body = XCDR (body);
}
- if (!NILP (body))
- {
- /* This can happen if functions like Fcond are the caller. */
- wrong_type_argument (Qlistp, body);
- }
-
UNGCPRO;
return val;
}
return base_variable;
}
+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;
+}
DEFUN ("defvar", Fdefvar, Sdefvar, 1, UNEVALLED, 0,
doc: /* Define SYMBOL as a variable, and return SYMBOL.
else
{ /* Check if there is really a global binding rather than just a let
binding that shadows the global unboundness of the var. */
- union specbinding *pdl = specpdl_ptr;
- while (pdl > specpdl)
+ union specbinding *binding = default_toplevel_binding (sym);
+ if (binding && EQ (specpdl_old_value (binding), Qunbound))
{
- if ((--pdl)->kind >= SPECPDL_LET
- && EQ (specpdl_symbol (pdl), sym)
- && EQ (specpdl_old_value (pdl), Qunbound))
- {
- message_with_string
- ("Warning: defvar ignored because %s is let-bound",
- SYMBOL_NAME (sym), 1);
- break;
- }
+ set_specpdl_old_value (binding, eval_sub (XCAR (tail)));
}
}
tail = XCDR (tail);
\f
DEFUN ("eval", Feval, Seval, 1, 2, 0,
doc: /* Evaluate FORM and return its value.
-If LEXICAL is t, evaluate using lexical scoping. */)
+If LEXICAL is t, evaluate using lexical scoping.
+LEXICAL can also be an actual lexical environment, in the form of an
+alist mapping symbols to their value. */)
(Lisp_Object form, Lisp_Object lexical)
{
ptrdiff_t count = SPECPDL_INDEX ();
/* Optimize for no indirection. */
fun = original_fun;
- if (SYMBOLP (fun) && !NILP (fun)
- && (fun = XSYMBOL (fun)->function, SYMBOLP (fun)))
+ if (!SYMBOLP (fun))
+ fun = Ffunction (Fcons (fun, Qnil));
+ else if (!NILP (fun) && (fun = XSYMBOL (fun)->function, SYMBOLP (fun)))
fun = indirect_function (fun);
if (SUBRP (fun))
return 0;
}
-/* `specpdl_ptr->symbol' is a field which describes which variable is
+/* `specpdl_ptr' describes which variable is
let-bound, so it can be properly undone when we unbind_to.
- It can have the following two shapes:
- - SYMBOL : if it's a plain symbol, it means that we have let-bound
- a symbol that is not buffer-local (at least at the time
- the let binding started). Note also that it should not be
+ It can be either a plain SPECPDL_LET or a SPECPDL_LET_LOCAL/DEFAULT.
+ - SYMBOL is the variable being bound. Note that it should not be
aliased (i.e. when let-binding V1 that's aliased to V2, we want
to record V2 here).
- - (SYMBOL WHERE . BUFFER) : this means that it is a let-binding for
- variable SYMBOL which can be buffer-local. WHERE tells us
- which buffer is affected (or nil if the let-binding affects the
- global value of the variable) and BUFFER tells us which buffer was
- current (i.e. if WHERE is non-nil, then BUFFER==WHERE, otherwise
- BUFFER did not yet have a buffer-local value). */
+ - WHERE tells us in which buffer the binding took place.
+ This is used for SPECPDL_LET_LOCAL bindings (i.e. bindings to a
+ buffer-local variable) as well as for SPECPDL_LET_DEFAULT bindings,
+ i.e. bindings to the default value of a variable which can be
+ buffer-local. */
void
specbind (Lisp_Object symbol, Lisp_Object value)
It need not be at the top of the stack. Discard the entry's
previous value without invoking it. */
+void
+set_unwind_protect (ptrdiff_t count, void (*func) (Lisp_Object),
+ Lisp_Object arg)
+{
+ union specbinding *p = specpdl + count;
+ p->unwind.kind = SPECPDL_UNWIND;
+ p->unwind.func = func;
+ p->unwind.arg = arg;
+}
+
void
set_unwind_protect_ptr (ptrdiff_t count, void (*func) (void *), void *arg)
{
case SPECPDL_UNWIND_VOID:
specpdl_ptr->unwind_void.func ();
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 (XSYMBOL (specpdl_symbol (specpdl_ptr))->redirect
- == SYMBOL_PLAINVAL)
- SET_SYMBOL_VAL (XSYMBOL (specpdl_symbol (specpdl_ptr)),
- specpdl_old_value (specpdl_ptr));
- else
- /* NOTE: we only ever come here if make_local_foo was used for
- the first time on this var within this let. */
- Fset_default (specpdl_symbol (specpdl_ptr),
- specpdl_old_value (specpdl_ptr));
- break;
case SPECPDL_BACKTRACE:
break;
- case SPECPDL_LET_LOCAL:
+ 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. */
+ struct Lisp_Symbol *sym = XSYMBOL (specpdl_symbol (specpdl_ptr));
+ if (sym->redirect == SYMBOL_PLAINVAL)
+ {
+ SET_SYMBOL_VAL (sym, specpdl_old_value (specpdl_ptr));
+ break;
+ }
+ else
+ { /* FALLTHROUGH!!
+ NOTE: we only ever come here if make_local_foo was used for
+ the first time on this var within this let. */
+ }
+ }
case SPECPDL_LET_DEFAULT:
- { /* If the symbol is a list, it is really (SYMBOL WHERE
- . CURRENT-BUFFER) where WHERE is either nil, a buffer, or a
- frame. If WHERE is a buffer or frame, this indicates we
- bound a variable that had a buffer-local or frame-local
- binding. WHERE nil means that the variable had the default
- value when it was bound. CURRENT-BUFFER is the buffer that
- was current when the variable was bound. */
+ Fset_default (specpdl_symbol (specpdl_ptr),
+ specpdl_old_value (specpdl_ptr));
+ break;
+ case SPECPDL_LET_LOCAL:
+ {
Lisp_Object symbol = specpdl_symbol (specpdl_ptr);
Lisp_Object where = specpdl_where (specpdl_ptr);
Lisp_Object old_value = specpdl_old_value (specpdl_ptr);
eassert (BUFFERP (where));
- if (specpdl_ptr->kind == SPECPDL_LET_DEFAULT)
- Fset_default (symbol, old_value);
/* If this was a local binding, reset the value in the appropriate
buffer, but only if that buffer's binding still exists. */
- else if (!NILP (Flocal_variable_p (symbol, where)))
+ if (!NILP (Flocal_variable_p (symbol, where)))
set_internal (symbol, old_value, where, 1);
}
break;
return Qnil;
}
-DEFUN ("backtrace-frame", Fbacktrace_frame, Sbacktrace_frame, 1, 1, NULL,
+static union specbinding *
+get_backtrace_frame (Lisp_Object nframes, Lisp_Object base)
+{
+ union specbinding *pdl = backtrace_top ();
+ register EMACS_INT i;
+
+ CHECK_NATNUM (nframes);
+
+ if (!NILP (base))
+ { /* Skip up to `base'. */
+ base = Findirect_function (base, Qt);
+ while (backtrace_p (pdl)
+ && !EQ (base, Findirect_function (backtrace_function (pdl), Qt)))
+ pdl = backtrace_next (pdl);
+ }
+
+ /* Find the frame requested. */
+ for (i = XFASTINT (nframes); i > 0 && backtrace_p (pdl); i--)
+ pdl = backtrace_next (pdl);
+
+ return pdl;
+}
+
+DEFUN ("backtrace-frame", Fbacktrace_frame, Sbacktrace_frame, 1, 2, NULL,
doc: /* Return the function and arguments NFRAMES up from current execution point.
If that frame has not evaluated the arguments yet (or is a special form),
the value is (nil FUNCTION ARG-FORMS...).
A &rest arg is represented as the tail of the list ARG-VALUES.
FUNCTION is whatever was supplied as car of evaluated list,
or a lambda expression for macro calls.
-If NFRAMES is more than the number of frames, the value is nil. */)
- (Lisp_Object nframes)
+If NFRAMES is more than the number of frames, the value is nil.
+If BASE is non-nil, it should be a function and NFRAMES counts from its
+nearest activation frame. */)
+ (Lisp_Object nframes, Lisp_Object base)
{
- union specbinding *pdl = backtrace_top ();
- register EMACS_INT i;
-
- CHECK_NATNUM (nframes);
-
- /* Find the frame requested. */
- for (i = 0; backtrace_p (pdl) && i < XFASTINT (nframes); i++)
- pdl = backtrace_next (pdl);
+ union specbinding *pdl = get_backtrace_frame (nframes, base);
if (!backtrace_p (pdl))
return Qnil;
}
}
+/* For backtrace-eval, we want to temporarily unwind the last few elements of
+ the specpdl stack, and then rewind them. We store the pre-unwind values
+ directly in the pre-existing specpdl elements (i.e. we swap the current
+ value and the old value stored in the specpdl), kind of like the inplace
+ pointer-reversal trick. As it turns out, the rewind does the same as the
+ unwind, except it starts from the other end of the specpdl stack, so we use
+ the same function for both unwind and rewind. */
+static void
+backtrace_eval_unrewind (int distance)
+{
+ union specbinding *tmp = specpdl_ptr;
+ int step = -1;
+ if (distance < 0)
+ { /* It's a rewind rather than unwind. */
+ tmp += distance - 1;
+ step = 1;
+ distance = -distance;
+ }
+
+ for (; distance > 0; distance--)
+ {
+ tmp += step;
+ /* */
+ switch (tmp->kind)
+ {
+ /* FIXME: Ideally we'd like to "temporarily unwind" (some of) those
+ unwind_protect, but the problem is that we don't know how to
+ rewind them afterwards. */
+ case SPECPDL_UNWIND:
+ case SPECPDL_UNWIND_PTR:
+ case SPECPDL_UNWIND_INT:
+ case SPECPDL_UNWIND_VOID:
+ 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. */
+ struct Lisp_Symbol *sym = XSYMBOL (specpdl_symbol (tmp));
+ if (sym->redirect == SYMBOL_PLAINVAL)
+ {
+ Lisp_Object old_value = specpdl_old_value (tmp);
+ set_specpdl_old_value (tmp, SYMBOL_VAL (sym));
+ SET_SYMBOL_VAL (sym, old_value);
+ break;
+ }
+ else
+ { /* FALLTHROUGH!!
+ NOTE: we only ever come here if make_local_foo was used for
+ the first time on this var within this let. */
+ }
+ }
+ case SPECPDL_LET_DEFAULT:
+ {
+ Lisp_Object sym = specpdl_symbol (tmp);
+ Lisp_Object old_value = specpdl_old_value (tmp);
+ set_specpdl_old_value (tmp, Fdefault_value (sym));
+ Fset_default (sym, old_value);
+ }
+ break;
+ case SPECPDL_LET_LOCAL:
+ {
+ Lisp_Object symbol = specpdl_symbol (tmp);
+ Lisp_Object where = specpdl_where (tmp);
+ Lisp_Object old_value = specpdl_old_value (tmp);
+ eassert (BUFFERP (where));
+
+ /* 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_specpdl_old_value
+ (tmp, Fbuffer_local_value (symbol, where));
+ set_internal (symbol, old_value, where, 1);
+ }
+ }
+ break;
+ }
+ }
+}
+
+DEFUN ("backtrace-eval", Fbacktrace_eval, Sbacktrace_eval, 2, 3, NULL,
+ doc: /* Evaluate EXP in the context of some activation frame.
+NFRAMES and BASE specify the activation frame to use, as in `backtrace-frame'. */)
+ (Lisp_Object exp, Lisp_Object nframes, Lisp_Object base)
+{
+ union specbinding *pdl = get_backtrace_frame (nframes, base);
+ ptrdiff_t count = SPECPDL_INDEX ();
+ ptrdiff_t distance = specpdl_ptr - pdl;
+ eassert (distance >= 0);
+
+ if (!backtrace_p (pdl))
+ error ("Activation frame not found!");
+
+ backtrace_eval_unrewind (distance);
+ record_unwind_protect_int (backtrace_eval_unrewind, -distance);
+
+ /* Use eval_sub rather than Feval since the main motivation behind
+ backtrace-eval is to be able to get/set the value of lexical variables
+ from the debugger. */
+ return unbind_to (count, eval_sub (exp));
+}
\f
void
mark_specpdl (void)
defsubr (&Ssetq);
defsubr (&Squote);
defsubr (&Sfunction);
+ defsubr (&Sdefault_toplevel_value);
+ defsubr (&Sset_default_toplevel_value);
defsubr (&Sdefvar);
defsubr (&Sdefvaralias);
defsubr (&Sdefconst);
defsubr (&Sbacktrace_debug);
defsubr (&Sbacktrace);
defsubr (&Sbacktrace_frame);
+ defsubr (&Sbacktrace_eval);
defsubr (&Sspecial_variable_p);
defsubr (&Sfunctionp);
}
HCoop / bpt / emacs.git / blobdiff