Mercurial > hg > xemacs-beta
diff src/symbols.c @ 428:3ecd8885ac67 r21-2-22
Import from CVS: tag r21-2-22
author | cvs |
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date | Mon, 13 Aug 2007 11:28:15 +0200 |
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children | 8de8e3f6228a |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/symbols.c Mon Aug 13 11:28:15 2007 +0200 @@ -0,0 +1,3424 @@ +/* "intern" and friends -- moved here from lread.c and data.c + Copyright (C) 1985-1989, 1992-1994 Free Software Foundation, Inc. + Copyright (C) 1995 Ben Wing. + +This file is part of XEmacs. + +XEmacs is free software; you can redistribute it and/or modify it +under the terms of the GNU General Public License as published by the +Free Software Foundation; either version 2, or (at your option) any +later version. + +XEmacs is distributed in the hope that it will be useful, but WITHOUT +ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received a copy of the GNU General Public License +along with XEmacs; see the file COPYING. If not, write to +the Free Software Foundation, Inc., 59 Temple Place - Suite 330, +Boston, MA 02111-1307, USA. */ + +/* Synched up with: FSF 19.30. */ + +/* This file has been Mule-ized. */ + +/* NOTE: + + The value cell of a symbol can contain a simple value or one of + various symbol-value-magic objects. Some of these objects can + chain into other kinds of objects. Here is a table of possibilities: + + 1a) simple value + 1b) Qunbound + 1c) symbol-value-forward, excluding Qunbound + 2) symbol-value-buffer-local -> 1a or 1b or 1c + 3) symbol-value-lisp-magic -> 1a or 1b or 1c + 4) symbol-value-lisp-magic -> symbol-value-buffer-local -> 1a or 1b or 1c + 5) symbol-value-varalias + 6) symbol-value-lisp-magic -> symbol-value-varalias + + The "chain" of a symbol-value-buffer-local is its current_value slot. + + The "chain" of a symbol-value-lisp-magic is its shadowed slot, which + applies for handler types without associated handlers. + + All other fields in all the structures (including the "shadowed" slot + in a symbol-value-varalias) can *only* contain a simple value or Qunbound. + +*/ + +/* #### Ugh, though, this file does awful things with symbol-value-magic + objects. This ought to be cleaned up. */ + +#include <config.h> +#include "lisp.h" + +#include "buffer.h" /* for Vbuffer_defaults */ +#include "console.h" +#include "elhash.h" + +Lisp_Object Qad_advice_info, Qad_activate; + +Lisp_Object Qget_value, Qset_value, Qbound_predicate, Qmake_unbound; +Lisp_Object Qlocal_predicate, Qmake_local; + +Lisp_Object Qboundp, Qglobally_boundp, Qmakunbound; +Lisp_Object Qsymbol_value, Qset, Qdefault_boundp, Qdefault_value; +Lisp_Object Qset_default, Qsetq_default; +Lisp_Object Qmake_variable_buffer_local, Qmake_local_variable; +Lisp_Object Qkill_local_variable, Qkill_console_local_variable; +Lisp_Object Qsymbol_value_in_buffer, Qsymbol_value_in_console; +Lisp_Object Qlocal_variable_p; + +Lisp_Object Qconst_integer, Qconst_boolean, Qconst_object; +Lisp_Object Qconst_specifier; +Lisp_Object Qdefault_buffer, Qcurrent_buffer, Qconst_current_buffer; +Lisp_Object Qdefault_console, Qselected_console, Qconst_selected_console; + +static Lisp_Object maybe_call_magic_handler (Lisp_Object sym, + Lisp_Object funsym, + int nargs, ...); +static Lisp_Object fetch_value_maybe_past_magic (Lisp_Object sym, + Lisp_Object follow_past_lisp_magic); +static Lisp_Object *value_slot_past_magic (Lisp_Object sym); +static Lisp_Object follow_varalias_pointers (Lisp_Object symbol, + Lisp_Object follow_past_lisp_magic); + + +static Lisp_Object +mark_symbol (Lisp_Object obj) +{ + struct Lisp_Symbol *sym = XSYMBOL (obj); + Lisp_Object pname; + + mark_object (sym->value); + mark_object (sym->function); + XSETSTRING (pname, sym->name); + mark_object (pname); + if (!symbol_next (sym)) + return sym->plist; + else + { + mark_object (sym->plist); + /* Mark the rest of the symbols in the obarray hash-chain */ + sym = symbol_next (sym); + XSETSYMBOL (obj, sym); + return obj; + } +} + +static const struct lrecord_description symbol_description[] = { + { XD_LISP_OBJECT, offsetof(struct Lisp_Symbol, next), 5 }, + { XD_END } +}; + +DEFINE_BASIC_LRECORD_IMPLEMENTATION ("symbol", symbol, + mark_symbol, print_symbol, 0, 0, 0, + symbol_description, struct Lisp_Symbol); + + +/**********************************************************************/ +/* Intern */ +/**********************************************************************/ + +/* #### using a vector here is way bogus. Use a hash table instead. */ + +Lisp_Object Vobarray; + +static Lisp_Object initial_obarray; + +/* oblookup stores the bucket number here, for the sake of Funintern. */ + +static int oblookup_last_bucket_number; + +static Lisp_Object +check_obarray (Lisp_Object obarray) +{ + while (!VECTORP (obarray) || XVECTOR_LENGTH (obarray) == 0) + { + /* If Vobarray is now invalid, force it to be valid. */ + if (EQ (Vobarray, obarray)) Vobarray = initial_obarray; + + obarray = wrong_type_argument (Qvectorp, obarray); + } + return obarray; +} + +Lisp_Object +intern (CONST char *str) +{ + Bytecount len = strlen (str); + CONST Bufbyte *buf = (CONST Bufbyte *) str; + Lisp_Object obarray = Vobarray; + + if (!VECTORP (obarray) || XVECTOR_LENGTH (obarray) == 0) + obarray = check_obarray (obarray); + + { + Lisp_Object tem = oblookup (obarray, buf, len); + if (SYMBOLP (tem)) + return tem; + } + + return Fintern (make_string (buf, len), obarray); +} + +DEFUN ("intern", Fintern, 1, 2, 0, /* +Return the canonical symbol whose name is STRING. +If there is none, one is created by this function and returned. +A second optional argument specifies the obarray to use; +it defaults to the value of `obarray'. +*/ + (string, obarray)) +{ + Lisp_Object object, *ptr; + struct Lisp_Symbol *symbol; + Bytecount len; + + if (NILP (obarray)) obarray = Vobarray; + obarray = check_obarray (obarray); + + CHECK_STRING (string); + + len = XSTRING_LENGTH (string); + object = oblookup (obarray, XSTRING_DATA (string), len); + if (!INTP (object)) + /* Found it */ + return object; + + ptr = &XVECTOR_DATA (obarray)[XINT (object)]; + + object = Fmake_symbol (string); + symbol = XSYMBOL (object); + + if (SYMBOLP (*ptr)) + symbol_next (symbol) = XSYMBOL (*ptr); + else + symbol_next (symbol) = 0; + *ptr = object; + + if (string_byte (symbol_name (symbol), 0) == ':' && EQ (obarray, Vobarray)) + { + /* The LISP way is to put keywords in their own package, but we + don't have packages, so we do something simpler. Someday, + maybe we'll have packages and then this will be reworked. + --Stig. */ + symbol_value (symbol) = object; + } + + return object; +} + +DEFUN ("intern-soft", Fintern_soft, 1, 2, 0, /* +Return the canonical symbol named NAME, or nil if none exists. +NAME may be a string or a symbol. If it is a symbol, that exact +symbol is searched for. +A second optional argument specifies the obarray to use; +it defaults to the value of `obarray'. +*/ + (name, obarray)) +{ + /* #### Bug! (intern-soft "nil") returns nil. Perhaps we should + add a DEFAULT-IF-NOT-FOUND arg, like in get. */ + Lisp_Object tem; + struct Lisp_String *string; + + if (NILP (obarray)) obarray = Vobarray; + obarray = check_obarray (obarray); + + if (!SYMBOLP (name)) + { + CHECK_STRING (name); + string = XSTRING (name); + } + else + string = symbol_name (XSYMBOL (name)); + + tem = oblookup (obarray, string_data (string), string_length (string)); + if (INTP (tem) || (SYMBOLP (name) && !EQ (name, tem))) + return Qnil; + else + return tem; +} + +DEFUN ("unintern", Funintern, 1, 2, 0, /* +Delete the symbol named NAME, if any, from OBARRAY. +The value is t if a symbol was found and deleted, nil otherwise. +NAME may be a string or a symbol. If it is a symbol, that symbol +is deleted, if it belongs to OBARRAY--no other symbol is deleted. +OBARRAY defaults to the value of the variable `obarray' +*/ + (name, obarray)) +{ + Lisp_Object tem; + struct Lisp_String *string; + int hash; + + if (NILP (obarray)) obarray = Vobarray; + obarray = check_obarray (obarray); + + if (SYMBOLP (name)) + string = symbol_name (XSYMBOL (name)); + else + { + CHECK_STRING (name); + string = XSTRING (name); + } + + tem = oblookup (obarray, string_data (string), string_length (string)); + if (INTP (tem)) + return Qnil; + /* If arg was a symbol, don't delete anything but that symbol itself. */ + if (SYMBOLP (name) && !EQ (name, tem)) + return Qnil; + + hash = oblookup_last_bucket_number; + + if (EQ (XVECTOR_DATA (obarray)[hash], tem)) + { + if (XSYMBOL (tem)->next) + XSETSYMBOL (XVECTOR_DATA (obarray)[hash], XSYMBOL (tem)->next); + else + XVECTOR_DATA (obarray)[hash] = Qzero; + } + else + { + Lisp_Object tail, following; + + for (tail = XVECTOR_DATA (obarray)[hash]; + XSYMBOL (tail)->next; + tail = following) + { + XSETSYMBOL (following, XSYMBOL (tail)->next); + if (EQ (following, tem)) + { + XSYMBOL (tail)->next = XSYMBOL (following)->next; + break; + } + } + } + return Qt; +} + +/* Return the symbol in OBARRAY whose names matches the string + of SIZE characters at PTR. If there is no such symbol in OBARRAY, + return the index into OBARRAY that the string hashes to. + + Also store the bucket number in oblookup_last_bucket_number. */ + +Lisp_Object +oblookup (Lisp_Object obarray, CONST Bufbyte *ptr, Bytecount size) +{ + int hash, obsize; + struct Lisp_Symbol *tail; + Lisp_Object bucket; + + if (!VECTORP (obarray) || + (obsize = XVECTOR_LENGTH (obarray)) == 0) + { + obarray = check_obarray (obarray); + obsize = XVECTOR_LENGTH (obarray); + } + hash = hash_string (ptr, size) % obsize; + oblookup_last_bucket_number = hash; + bucket = XVECTOR_DATA (obarray)[hash]; + if (ZEROP (bucket)) + ; + else if (!SYMBOLP (bucket)) + error ("Bad data in guts of obarray"); /* Like CADR error message */ + else + for (tail = XSYMBOL (bucket); ;) + { + if (string_length (tail->name) == size && + !memcmp (string_data (tail->name), ptr, size)) + { + XSETSYMBOL (bucket, tail); + return bucket; + } + tail = symbol_next (tail); + if (!tail) + break; + } + return make_int (hash); +} + +#if 0 /* Emacs 19.34 */ +int +hash_string (CONST Bufbyte *ptr, Bytecount len) +{ + CONST Bufbyte *p = ptr; + CONST Bufbyte *end = p + len; + Bufbyte c; + int hash = 0; + + while (p != end) + { + c = *p++; + if (c >= 0140) c -= 40; + hash = ((hash<<3) + (hash>>28) + c); + } + return hash & 07777777777; +} +#endif + +/* derived from hashpjw, Dragon Book P436. */ +int +hash_string (CONST Bufbyte *ptr, Bytecount len) +{ + int hash = 0; + + while (len-- > 0) + { + int g; + hash = (hash << 4) + *ptr++; + g = hash & 0xf0000000; + if (g) + hash = (hash ^ (g >> 24)) ^ g; + } + return hash & 07777777777; +} + +/* Map FN over OBARRAY. The mapping is stopped when FN returns a + non-zero value. */ +void +map_obarray (Lisp_Object obarray, + int (*fn) (Lisp_Object, void *), void *arg) +{ + REGISTER int i; + + CHECK_VECTOR (obarray); + for (i = XVECTOR_LENGTH (obarray) - 1; i >= 0; i--) + { + Lisp_Object tail = XVECTOR_DATA (obarray)[i]; + if (SYMBOLP (tail)) + while (1) + { + struct Lisp_Symbol *next; + if ((*fn) (tail, arg)) + return; + next = symbol_next (XSYMBOL (tail)); + if (!next) + break; + XSETSYMBOL (tail, next); + } + } +} + +static int +mapatoms_1 (Lisp_Object sym, void *arg) +{ + call1 (*(Lisp_Object *)arg, sym); + return 0; +} + +DEFUN ("mapatoms", Fmapatoms, 1, 2, 0, /* +Call FUNCTION on every symbol in OBARRAY. +OBARRAY defaults to the value of `obarray'. +*/ + (function, obarray)) +{ + if (NILP (obarray)) + obarray = Vobarray; + obarray = check_obarray (obarray); + + map_obarray (obarray, mapatoms_1, &function); + return Qnil; +} + + +/**********************************************************************/ +/* Apropos */ +/**********************************************************************/ + +struct appropos_mapper_closure +{ + Lisp_Object regexp; + Lisp_Object predicate; + Lisp_Object accumulation; +}; + +static int +apropos_mapper (Lisp_Object symbol, void *arg) +{ + struct appropos_mapper_closure *closure = + (struct appropos_mapper_closure *) arg; + Bytecount match = fast_lisp_string_match (closure->regexp, + Fsymbol_name (symbol)); + + if (match >= 0 && + (NILP (closure->predicate) || + !NILP (call1 (closure->predicate, symbol)))) + closure->accumulation = Fcons (symbol, closure->accumulation); + + return 0; +} + +DEFUN ("apropos-internal", Fapropos_internal, 1, 2, 0, /* +Show all symbols whose names contain match for REGEXP. +If optional 2nd arg PREDICATE is non-nil, (funcall PREDICATE SYMBOL) + is done for each symbol and a symbol is mentioned only if that + returns non-nil. +Return list of symbols found. +*/ + (regexp, predicate)) +{ + struct appropos_mapper_closure closure; + + CHECK_STRING (regexp); + + closure.regexp = regexp; + closure.predicate = predicate; + closure.accumulation = Qnil; + map_obarray (Vobarray, apropos_mapper, &closure); + closure.accumulation = Fsort (closure.accumulation, Qstring_lessp); + return closure.accumulation; +} + + +/* Extract and set components of symbols */ + +static void set_up_buffer_local_cache (Lisp_Object sym, + struct symbol_value_buffer_local *bfwd, + struct buffer *buf, + Lisp_Object new_alist_el, + int set_it_p); + +DEFUN ("boundp", Fboundp, 1, 1, 0, /* +Return t if SYMBOL's value is not void. +*/ + (symbol)) +{ + CHECK_SYMBOL (symbol); + return UNBOUNDP (find_symbol_value (symbol)) ? Qnil : Qt; +} + +DEFUN ("globally-boundp", Fglobally_boundp, 1, 1, 0, /* +Return t if SYMBOL has a global (non-bound) value. +This is for the byte-compiler; you really shouldn't be using this. +*/ + (symbol)) +{ + CHECK_SYMBOL (symbol); + return UNBOUNDP (top_level_value (symbol)) ? Qnil : Qt; +} + +DEFUN ("fboundp", Ffboundp, 1, 1, 0, /* +Return t if SYMBOL's function definition is not void. +*/ + (symbol)) +{ + CHECK_SYMBOL (symbol); + return UNBOUNDP (XSYMBOL (symbol)->function) ? Qnil : Qt; +} + +/* Return non-zero if SYM's value or function (the current contents of + which should be passed in as VAL) is constant, i.e. unsettable. */ + +static int +symbol_is_constant (Lisp_Object sym, Lisp_Object val) +{ + /* #### - I wonder if it would be better to just have a new magic value + type and make nil, t, and all keywords have that same magic + constant_symbol value. This test is awfully specific about what is + constant and what isn't. --Stig */ + if (EQ (sym, Qnil) || + EQ (sym, Qt)) + return 1; + + if (SYMBOL_VALUE_MAGIC_P (val)) + switch (XSYMBOL_VALUE_MAGIC_TYPE (val)) + { + case SYMVAL_CONST_OBJECT_FORWARD: + case SYMVAL_CONST_SPECIFIER_FORWARD: + case SYMVAL_CONST_FIXNUM_FORWARD: + case SYMVAL_CONST_BOOLEAN_FORWARD: + case SYMVAL_CONST_CURRENT_BUFFER_FORWARD: + case SYMVAL_CONST_SELECTED_CONSOLE_FORWARD: + return 1; + default: break; /* Warning suppression */ + } + + /* We don't return true for keywords here because they are handled + specially by reject_constant_symbols(). */ + return 0; +} + +/* We are setting SYM's value slot (or function slot, if FUNCTION_P is + non-zero) to NEWVAL. Make sure this is allowed. + FOLLOW_PAST_LISP_MAGIC specifies whether we delve past + symbol-value-lisp-magic objects. */ + +void +reject_constant_symbols (Lisp_Object sym, Lisp_Object newval, int function_p, + Lisp_Object follow_past_lisp_magic) +{ + Lisp_Object val = + (function_p ? XSYMBOL (sym)->function + : fetch_value_maybe_past_magic (sym, follow_past_lisp_magic)); + + if (SYMBOL_VALUE_MAGIC_P (val) && + XSYMBOL_VALUE_MAGIC_TYPE (val) == SYMVAL_CONST_SPECIFIER_FORWARD) + signal_simple_error ("Use `set-specifier' to change a specifier's value", + sym); + + if (symbol_is_constant (sym, val) + || (SYMBOL_IS_KEYWORD (sym) && !EQ (newval, sym))) + signal_error (Qsetting_constant, + UNBOUNDP (newval) ? list1 (sym) : list2 (sym, newval)); +} + +/* Verify that it's ok to make SYM buffer-local. This rejects + constants and default-buffer-local variables. FOLLOW_PAST_LISP_MAGIC + specifies whether we delve into symbol-value-lisp-magic objects. + (Should be a symbol indicating what action is being taken; that way, + we don't delve if there's a handler for that action, but do otherwise.) */ + +static void +verify_ok_for_buffer_local (Lisp_Object sym, + Lisp_Object follow_past_lisp_magic) +{ + Lisp_Object val = fetch_value_maybe_past_magic (sym, follow_past_lisp_magic); + + if (symbol_is_constant (sym, val)) + goto not_ok; + if (SYMBOL_VALUE_MAGIC_P (val)) + switch (XSYMBOL_VALUE_MAGIC_TYPE (val)) + { + case SYMVAL_DEFAULT_BUFFER_FORWARD: + case SYMVAL_DEFAULT_CONSOLE_FORWARD: + /* #### It's theoretically possible for it to be reasonable + to have both console-local and buffer-local variables, + but I don't want to consider that right now. */ + case SYMVAL_SELECTED_CONSOLE_FORWARD: + goto not_ok; + default: break; /* Warning suppression */ + } + + return; + + not_ok: + signal_error (Qerror, + list2 (build_string ("Symbol may not be buffer-local"), sym)); +} + +DEFUN ("makunbound", Fmakunbound, 1, 1, 0, /* +Make SYMBOL's value be void. +*/ + (symbol)) +{ + Fset (symbol, Qunbound); + return symbol; +} + +DEFUN ("fmakunbound", Ffmakunbound, 1, 1, 0, /* +Make SYMBOL's function definition be void. +*/ + (symbol)) +{ + CHECK_SYMBOL (symbol); + reject_constant_symbols (symbol, Qunbound, 1, Qt); + XSYMBOL (symbol)->function = Qunbound; + return symbol; +} + +DEFUN ("symbol-function", Fsymbol_function, 1, 1, 0, /* +Return SYMBOL's function definition. Error if that is void. +*/ + (symbol)) +{ + CHECK_SYMBOL (symbol); + if (UNBOUNDP (XSYMBOL (symbol)->function)) + signal_void_function_error (symbol); + return XSYMBOL (symbol)->function; +} + +DEFUN ("symbol-plist", Fsymbol_plist, 1, 1, 0, /* +Return SYMBOL's property list. +*/ + (symbol)) +{ + CHECK_SYMBOL (symbol); + return XSYMBOL (symbol)->plist; +} + +DEFUN ("symbol-name", Fsymbol_name, 1, 1, 0, /* +Return SYMBOL's name, a string. +*/ + (symbol)) +{ + Lisp_Object name; + + CHECK_SYMBOL (symbol); + XSETSTRING (name, XSYMBOL (symbol)->name); + return name; +} + +DEFUN ("fset", Ffset, 2, 2, 0, /* +Set SYMBOL's function definition to NEWDEF, and return NEWDEF. +*/ + (symbol, newdef)) +{ + /* This function can GC */ + CHECK_SYMBOL (symbol); + reject_constant_symbols (symbol, newdef, 1, Qt); + if (!NILP (Vautoload_queue) && !UNBOUNDP (XSYMBOL (symbol)->function)) + Vautoload_queue = Fcons (Fcons (symbol, XSYMBOL (symbol)->function), + Vautoload_queue); + XSYMBOL (symbol)->function = newdef; + /* Handle automatic advice activation */ + if (CONSP (XSYMBOL (symbol)->plist) && + !NILP (Fget (symbol, Qad_advice_info, Qnil))) + { + call2 (Qad_activate, symbol, Qnil); + newdef = XSYMBOL (symbol)->function; + } + return newdef; +} + +/* FSFmacs */ +DEFUN ("define-function", Fdefine_function, 2, 2, 0, /* +Set SYMBOL's function definition to NEWDEF, and return NEWDEF. +Associates the function with the current load file, if any. +*/ + (symbol, newdef)) +{ + /* This function can GC */ + Ffset (symbol, newdef); + LOADHIST_ATTACH (symbol); + return newdef; +} + + +DEFUN ("setplist", Fsetplist, 2, 2, 0, /* +Set SYMBOL's property list to NEWPLIST, and return NEWPLIST. +*/ + (symbol, newplist)) +{ + CHECK_SYMBOL (symbol); +#if 0 /* Inserted for debugging 6/28/1997 -slb */ + /* Somebody is setting a property list of integer 0, who? */ + /* Not this way apparently. */ + if (EQ(newplist, Qzero)) abort(); +#endif + + XSYMBOL (symbol)->plist = newplist; + return newplist; +} + + +/**********************************************************************/ +/* symbol-value */ +/**********************************************************************/ + +/* If the contents of the value cell of a symbol is one of the following + three types of objects, then the symbol is "magic" in that setting + and retrieving its value doesn't just set or retrieve the raw + contents of the value cell. None of these objects can escape to + the user level, so there is no loss of generality. + + If a symbol is "unbound", then the contents of its value cell is + Qunbound. Despite appearances, this is *not* a symbol, but is a + symbol-value-forward object. This is so that printing it results + in "INTERNAL OBJECT (XEmacs bug?)", in case it leaks to Lisp, somehow. + + Logically all of the following objects are "symbol-value-magic" + objects, and there are some games played w.r.t. this (#### this + should be cleaned up). SYMBOL_VALUE_MAGIC_P is true for all of + the object types. XSYMBOL_VALUE_MAGIC_TYPE returns the type of + symbol-value-magic object. There are more than three types + returned by this macro: in particular, symbol-value-forward + has eight subtypes, and symbol-value-buffer-local has two. See + symeval.h. + + 1. symbol-value-forward + + symbol-value-forward is used for variables whose actual contents + are stored in a C variable of some sort, and for Qunbound. The + lcheader.next field (which is only used to chain together free + lcrecords) holds a pointer to the actual C variable. Included + in this type are "buffer-local" variables that are actually + stored in the buffer object itself; in this case, the "pointer" + is an offset into the struct buffer structure. + + The subtypes are as follows: + + SYMVAL_OBJECT_FORWARD: + (declare with DEFVAR_LISP) + The value of this variable is stored in a C variable of type + "Lisp_Object". Setting this variable sets the C variable. + Accessing this variable retrieves a value from the C variable. + These variables can be buffer-local -- in this case, the + raw symbol-value field gets converted into a + symbol-value-buffer-local, whose "current_value" slot contains + the symbol-value-forward. (See below.) + + SYMVAL_FIXNUM_FORWARD: + SYMVAL_BOOLEAN_FORWARD: + (declare with DEFVAR_INT or DEFVAR_BOOL) + Similar to SYMVAL_OBJECT_FORWARD except that the C variable + is of type "int" and is an integer or boolean, respectively. + + SYMVAL_CONST_OBJECT_FORWARD: + SYMVAL_CONST_FIXNUM_FORWARD: + SYMVAL_CONST_BOOLEAN_FORWARD: + (declare with DEFVAR_CONST_LISP, DEFVAR_CONST_INT, or + DEFVAR_CONST_BOOL) + Similar to SYMVAL_OBJECT_FORWARD, SYMVAL_FIXNUM_FORWARD, or + SYMVAL_BOOLEAN_FORWARD, respectively, except that the value cannot + be changed. + + SYMVAL_CONST_SPECIFIER_FORWARD: + (declare with DEFVAR_SPECIFIER) + Exactly like SYMVAL_CONST_OBJECT_FORWARD except that error message + you get when attempting to set the value says to use + `set-specifier' instead. + + SYMVAL_CURRENT_BUFFER_FORWARD: + (declare with DEFVAR_BUFFER_LOCAL) + This is used for built-in buffer-local variables -- i.e. + Lisp variables whose value is stored in the "struct buffer". + Variables of this sort always forward into C "Lisp_Object" + fields (although there's no reason in principle that other + types for ints and booleans couldn't be added). Note that + some of these variables are automatically local in each + buffer, while some are only local when they become set + (similar to `make-variable-buffer-local'). In these latter + cases, of course, the default value shows through in all + buffers in which the variable doesn't have a local value. + This is implemented by making sure the "struct buffer" field + always contains the correct value (whether it's local or + a default) and maintaining a mask in the "struct buffer" + indicating which fields are local. When `set-default' is + called on a variable that's not always local to all buffers, + it loops through each buffer and sets the corresponding + field in each buffer without a local value for the field, + according to the mask. + + Calling `make-local-variable' on a variable of this sort + only has the effect of maybe changing the current buffer's mask. + Calling `make-variable-buffer-local' on a variable of this + sort has no effect at all. + + SYMVAL_CONST_CURRENT_BUFFER_FORWARD: + (declare with DEFVAR_CONST_BUFFER_LOCAL) + Same as SYMVAL_CURRENT_BUFFER_FORWARD except that the + value cannot be set. + + SYMVAL_DEFAULT_BUFFER_FORWARD: + (declare with DEFVAR_BUFFER_DEFAULTS) + This is used for the Lisp variables that contain the + default values of built-in buffer-local variables. Setting + or referencing one of these variables forwards into a slot + in the special struct buffer Vbuffer_defaults. + + SYMVAL_UNBOUND_MARKER: + This is used for only one object, Qunbound. + + SYMVAL_SELECTED_CONSOLE_FORWARD: + (declare with DEFVAR_CONSOLE_LOCAL) + This is used for built-in console-local variables -- i.e. + Lisp variables whose value is stored in the "struct console". + These work just like built-in buffer-local variables. + However, calling `make-local-variable' or + `make-variable-buffer-local' on one of these variables + is currently disallowed because that would entail having + both console-local and buffer-local variables, which is + trickier to implement. + + SYMVAL_CONST_SELECTED_CONSOLE_FORWARD: + (declare with DEFVAR_CONST_CONSOLE_LOCAL) + Same as SYMVAL_SELECTED_CONSOLE_FORWARD except that the + value cannot be set. + + SYMVAL_DEFAULT_CONSOLE_FORWARD: + (declare with DEFVAR_CONSOLE_DEFAULTS) + This is used for the Lisp variables that contain the + default values of built-in console-local variables. Setting + or referencing one of these variables forwards into a slot + in the special struct console Vconsole_defaults. + + + 2. symbol-value-buffer-local + + symbol-value-buffer-local is used for variables that have had + `make-local-variable' or `make-variable-buffer-local' applied + to them. This object contains an alist mapping buffers to + values. In addition, the object contains a "current value", + which is the value in some buffer. Whenever you access the + variable with `symbol-value' or set it with `set' or `setq', + things are switched around so that the "current value" + refers to the current buffer, if it wasn't already. This + way, repeated references to a variable in the same buffer + are almost as efficient as if the variable weren't buffer + local. Note that the alist may not be up-to-date w.r.t. + the buffer whose value is current, as the "current value" + cache is normally only flushed into the alist when the + buffer it refers to changes. + + Note also that it is possible for `make-local-variable' + or `make-variable-buffer-local' to be called on a variable + that forwards into a C variable (i.e. a variable whose + value cell is a symbol-value-forward). In this case, + the value cell becomes a symbol-value-buffer-local (as + always), and the symbol-value-forward moves into + the "current value" cell in this object. Also, in + this case the "current value" *always* refers to the + current buffer, so that the values of the C variable + always is the correct value for the current buffer. + set_buffer_internal() automatically updates the current-value + cells of all buffer-local variables that forward into C + variables. (There is a list of all buffer-local variables + that is maintained for this and other purposes.) + + Note that only certain types of `symbol-value-forward' objects + can find their way into the "current value" cell of a + `symbol-value-buffer-local' object: SYMVAL_OBJECT_FORWARD, + SYMVAL_FIXNUM_FORWARD, SYMVAL_BOOLEAN_FORWARD, and + SYMVAL_UNBOUND_MARKER. The SYMVAL_CONST_*_FORWARD cannot + be buffer-local because they are unsettable; + SYMVAL_DEFAULT_*_FORWARD cannot be buffer-local because that + makes no sense; making SYMVAL_CURRENT_BUFFER_FORWARD buffer-local + does not have much of an effect (it's already buffer-local); and + SYMVAL_SELECTED_CONSOLE_FORWARD cannot be buffer-local because + that's not currently implemented. + + + 3. symbol-value-varalias + + A symbol-value-varalias object is used for variables that + are aliases for other variables. This object contains + the symbol that this variable is aliased to. + symbol-value-varalias objects cannot occur anywhere within + a symbol-value-buffer-local object, and most of the + low-level functions below do not accept them; you need + to call follow_varalias_pointers to get the actual + symbol to operate on. */ + +static Lisp_Object +mark_symbol_value_buffer_local (Lisp_Object obj) +{ + struct symbol_value_buffer_local *bfwd; + +#ifdef ERROR_CHECK_TYPECHECK + assert (XSYMBOL_VALUE_MAGIC_TYPE (obj) == SYMVAL_BUFFER_LOCAL || + XSYMBOL_VALUE_MAGIC_TYPE (obj) == SYMVAL_SOME_BUFFER_LOCAL); +#endif + + bfwd = XSYMBOL_VALUE_BUFFER_LOCAL (obj); + mark_object (bfwd->default_value); + mark_object (bfwd->current_value); + mark_object (bfwd->current_buffer); + return bfwd->current_alist_element; +} + +static Lisp_Object +mark_symbol_value_lisp_magic (Lisp_Object obj) +{ + struct symbol_value_lisp_magic *bfwd; + int i; + + assert (XSYMBOL_VALUE_MAGIC_TYPE (obj) == SYMVAL_LISP_MAGIC); + + bfwd = XSYMBOL_VALUE_LISP_MAGIC (obj); + for (i = 0; i < MAGIC_HANDLER_MAX; i++) + { + mark_object (bfwd->handler[i]); + mark_object (bfwd->harg[i]); + } + return bfwd->shadowed; +} + +static Lisp_Object +mark_symbol_value_varalias (Lisp_Object obj) +{ + struct symbol_value_varalias *bfwd; + + assert (XSYMBOL_VALUE_MAGIC_TYPE (obj) == SYMVAL_VARALIAS); + + bfwd = XSYMBOL_VALUE_VARALIAS (obj); + mark_object (bfwd->shadowed); + return bfwd->aliasee; +} + +/* Should never, ever be called. (except by an external debugger) */ +void +print_symbol_value_magic (Lisp_Object obj, + Lisp_Object printcharfun, int escapeflag) +{ + char buf[200]; + sprintf (buf, "#<INTERNAL OBJECT (XEmacs bug?) (%s type %d) 0x%lx>", + XRECORD_LHEADER_IMPLEMENTATION (obj)->name, + XSYMBOL_VALUE_MAGIC_TYPE (obj), + (long) XPNTR (obj)); + write_c_string (buf, printcharfun); +} + +static const struct lrecord_description symbol_value_forward_description[] = { + { XD_END } +}; + +static const struct lrecord_description symbol_value_buffer_local_description[] = { + { XD_LISP_OBJECT, offsetof(struct symbol_value_buffer_local, default_value), 1 }, + { XD_LO_RESET_NIL, offsetof(struct symbol_value_buffer_local, current_value), 3 }, + { XD_END } +}; + +static const struct lrecord_description symbol_value_lisp_magic_description[] = { + { XD_LISP_OBJECT, offsetof(struct symbol_value_lisp_magic, handler), 2*MAGIC_HANDLER_MAX+1 }, + { XD_END } +}; + +static const struct lrecord_description symbol_value_varalias_description[] = { + { XD_LISP_OBJECT, offsetof(struct symbol_value_varalias, aliasee), 2 }, + { XD_END } +}; + +DEFINE_LRECORD_IMPLEMENTATION ("symbol-value-forward", + symbol_value_forward, + this_one_is_unmarkable, + print_symbol_value_magic, 0, 0, 0, + symbol_value_forward_description, + struct symbol_value_forward); + +DEFINE_LRECORD_IMPLEMENTATION ("symbol-value-buffer-local", + symbol_value_buffer_local, + mark_symbol_value_buffer_local, + print_symbol_value_magic, 0, 0, 0, + symbol_value_buffer_local_description, + struct symbol_value_buffer_local); + +DEFINE_LRECORD_IMPLEMENTATION ("symbol-value-lisp-magic", + symbol_value_lisp_magic, + mark_symbol_value_lisp_magic, + print_symbol_value_magic, 0, 0, 0, + symbol_value_lisp_magic_description, + struct symbol_value_lisp_magic); + +DEFINE_LRECORD_IMPLEMENTATION ("symbol-value-varalias", + symbol_value_varalias, + mark_symbol_value_varalias, + print_symbol_value_magic, 0, 0, 0, + symbol_value_varalias_description, + struct symbol_value_varalias); + + +/* Getting and setting values of symbols */ + +/* Given the raw contents of a symbol value cell, return the Lisp value of + the symbol. However, VALCONTENTS cannot be a symbol-value-buffer-local, + symbol-value-lisp-magic, or symbol-value-varalias. + + BUFFER specifies a buffer, and is used for built-in buffer-local + variables, which are of type SYMVAL_CURRENT_BUFFER_FORWARD. + Note that such variables are never encapsulated in a + symbol-value-buffer-local structure. + + CONSOLE specifies a console, and is used for built-in console-local + variables, which are of type SYMVAL_SELECTED_CONSOLE_FORWARD. + Note that such variables are (currently) never encapsulated in a + symbol-value-buffer-local structure. + */ + +static Lisp_Object +do_symval_forwarding (Lisp_Object valcontents, struct buffer *buffer, + struct console *console) +{ + CONST struct symbol_value_forward *fwd; + + if (!SYMBOL_VALUE_MAGIC_P (valcontents)) + return valcontents; + + fwd = XSYMBOL_VALUE_FORWARD (valcontents); + switch (fwd->magic.type) + { + case SYMVAL_FIXNUM_FORWARD: + case SYMVAL_CONST_FIXNUM_FORWARD: + return make_int (*((int *)symbol_value_forward_forward (fwd))); + + case SYMVAL_BOOLEAN_FORWARD: + case SYMVAL_CONST_BOOLEAN_FORWARD: + return *((int *)symbol_value_forward_forward (fwd)) ? Qt : Qnil; + + case SYMVAL_OBJECT_FORWARD: + case SYMVAL_CONST_OBJECT_FORWARD: + case SYMVAL_CONST_SPECIFIER_FORWARD: + return *((Lisp_Object *)symbol_value_forward_forward (fwd)); + + case SYMVAL_DEFAULT_BUFFER_FORWARD: + return (*((Lisp_Object *)((char *) XBUFFER (Vbuffer_defaults) + + ((char *)symbol_value_forward_forward (fwd) + - (char *)&buffer_local_flags)))); + + + case SYMVAL_CURRENT_BUFFER_FORWARD: + case SYMVAL_CONST_CURRENT_BUFFER_FORWARD: + assert (buffer); + return (*((Lisp_Object *)((char *)buffer + + ((char *)symbol_value_forward_forward (fwd) + - (char *)&buffer_local_flags)))); + + case SYMVAL_DEFAULT_CONSOLE_FORWARD: + return (*((Lisp_Object *)((char *) XCONSOLE (Vconsole_defaults) + + ((char *)symbol_value_forward_forward (fwd) + - (char *)&console_local_flags)))); + + case SYMVAL_SELECTED_CONSOLE_FORWARD: + case SYMVAL_CONST_SELECTED_CONSOLE_FORWARD: + assert (console); + return (*((Lisp_Object *)((char *)console + + ((char *)symbol_value_forward_forward (fwd) + - (char *)&console_local_flags)))); + + case SYMVAL_UNBOUND_MARKER: + return valcontents; + + default: + abort (); + } + return Qnil; /* suppress compiler warning */ +} + +/* Set the value of default-buffer-local variable SYM to VALUE. */ + +static void +set_default_buffer_slot_variable (Lisp_Object sym, + Lisp_Object value) +{ + /* Handle variables like case-fold-search that have special slots in + the buffer. Make them work apparently like buffer_local variables. + */ + /* At this point, the value cell may not contain a symbol-value-varalias + or symbol-value-buffer-local, and if there's a handler, we should + have already called it. */ + Lisp_Object valcontents = fetch_value_maybe_past_magic (sym, Qt); + CONST struct symbol_value_forward *fwd + = XSYMBOL_VALUE_FORWARD (valcontents); + int offset = ((char *) symbol_value_forward_forward (fwd) + - (char *) &buffer_local_flags); + int mask = XINT (*((Lisp_Object *) symbol_value_forward_forward (fwd))); + int (*magicfun) (Lisp_Object simm, Lisp_Object *val, Lisp_Object in_object, + int flags) = symbol_value_forward_magicfun (fwd); + + *((Lisp_Object *) (offset + (char *) XBUFFER (Vbuffer_defaults))) + = value; + + if (mask > 0) /* Not always per-buffer */ + { + Lisp_Object elt; + + /* Set value in each buffer which hasn't shadowed the default */ + LIST_LOOP_2 (elt, Vbuffer_alist) + { + struct buffer *b = XBUFFER (XCDR (elt)); + if (!(b->local_var_flags & mask)) + { + if (magicfun) + magicfun (sym, &value, make_buffer (b), 0); + *((Lisp_Object *) (offset + (char *) b)) = value; + } + } + } +} + +/* Set the value of default-console-local variable SYM to VALUE. */ + +static void +set_default_console_slot_variable (Lisp_Object sym, + Lisp_Object value) +{ + /* Handle variables like case-fold-search that have special slots in + the console. Make them work apparently like console_local variables. + */ + /* At this point, the value cell may not contain a symbol-value-varalias + or symbol-value-buffer-local, and if there's a handler, we should + have already called it. */ + Lisp_Object valcontents = fetch_value_maybe_past_magic (sym, Qt); + CONST struct symbol_value_forward *fwd + = XSYMBOL_VALUE_FORWARD (valcontents); + int offset = ((char *) symbol_value_forward_forward (fwd) + - (char *) &console_local_flags); + int mask = XINT (*((Lisp_Object *) symbol_value_forward_forward (fwd))); + int (*magicfun) (Lisp_Object simm, Lisp_Object *val, Lisp_Object in_object, + int flags) = symbol_value_forward_magicfun (fwd); + + *((Lisp_Object *) (offset + (char *) XCONSOLE (Vconsole_defaults))) + = value; + + if (mask > 0) /* Not always per-console */ + { + Lisp_Object console; + + /* Set value in each console which hasn't shadowed the default */ + LIST_LOOP_2 (console, Vconsole_list) + { + struct console *d = XCONSOLE (console); + if (!(d->local_var_flags & mask)) + { + if (magicfun) + magicfun (sym, &value, console, 0); + *((Lisp_Object *) (offset + (char *) d)) = value; + } + } + } +} + +/* Store NEWVAL into SYM. + + SYM's value slot may *not* be types (5) or (6) above, + i.e. no symbol-value-varalias objects. (You should have + forwarded past all of these.) + + SYM should not be an unsettable symbol or a symbol with + a magic `set-value' handler (unless you want to explicitly + ignore this handler). + + OVALUE is the current value of SYM, but forwarded past any + symbol-value-buffer-local and symbol-value-lisp-magic objects. + (i.e. if SYM is a symbol-value-buffer-local, OVALUE should be + the contents of its current-value cell.) NEWVAL may only be + a simple value or Qunbound. If SYM is a symbol-value-buffer-local, + this function will only modify its current-value cell, which should + already be set up to point to the current buffer. + */ + +static void +store_symval_forwarding (Lisp_Object sym, Lisp_Object ovalue, + Lisp_Object newval) +{ + if (!SYMBOL_VALUE_MAGIC_P (ovalue) || UNBOUNDP (ovalue)) + { + Lisp_Object *store_pointer = value_slot_past_magic (sym); + + if (SYMBOL_VALUE_BUFFER_LOCAL_P (*store_pointer)) + store_pointer = + &XSYMBOL_VALUE_BUFFER_LOCAL (*store_pointer)->current_value; + + assert (UNBOUNDP (*store_pointer) + || !SYMBOL_VALUE_MAGIC_P (*store_pointer)); + *store_pointer = newval; + } + else + { + CONST struct symbol_value_forward *fwd = XSYMBOL_VALUE_FORWARD (ovalue); + int (*magicfun) (Lisp_Object simm, Lisp_Object *val, + Lisp_Object in_object, int flags) + = symbol_value_forward_magicfun (fwd); + + switch (XSYMBOL_VALUE_MAGIC_TYPE (ovalue)) + { + case SYMVAL_FIXNUM_FORWARD: + CHECK_INT (newval); + if (magicfun) + magicfun (sym, &newval, Qnil, 0); + *((int *) symbol_value_forward_forward (fwd)) = XINT (newval); + return; + + case SYMVAL_BOOLEAN_FORWARD: + if (magicfun) + magicfun (sym, &newval, Qnil, 0); + *((int *) symbol_value_forward_forward (fwd)) + = !NILP (newval); + return; + + case SYMVAL_OBJECT_FORWARD: + if (magicfun) + magicfun (sym, &newval, Qnil, 0); + *((Lisp_Object *) symbol_value_forward_forward (fwd)) = newval; + return; + + case SYMVAL_DEFAULT_BUFFER_FORWARD: + set_default_buffer_slot_variable (sym, newval); + return; + + case SYMVAL_CURRENT_BUFFER_FORWARD: + if (magicfun) + magicfun (sym, &newval, make_buffer (current_buffer), 0); + *((Lisp_Object *) ((char *) current_buffer + + ((char *) symbol_value_forward_forward (fwd) + - (char *) &buffer_local_flags))) + = newval; + return; + + case SYMVAL_DEFAULT_CONSOLE_FORWARD: + set_default_console_slot_variable (sym, newval); + return; + + case SYMVAL_SELECTED_CONSOLE_FORWARD: + if (magicfun) + magicfun (sym, &newval, Vselected_console, 0); + *((Lisp_Object *) ((char *) XCONSOLE (Vselected_console) + + ((char *) symbol_value_forward_forward (fwd) + - (char *) &console_local_flags))) + = newval; + return; + + default: + abort (); + } + } +} + +/* Given a per-buffer variable SYMBOL and its raw value-cell contents + BFWD, locate and return a pointer to the element in BUFFER's + local_var_alist for SYMBOL. The return value will be Qnil if + BUFFER does not have its own value for SYMBOL (i.e. the default + value is seen in that buffer). + */ + +static Lisp_Object +buffer_local_alist_element (struct buffer *buffer, Lisp_Object symbol, + struct symbol_value_buffer_local *bfwd) +{ + if (!NILP (bfwd->current_buffer) && + XBUFFER (bfwd->current_buffer) == buffer) + /* This is just an optimization of the below. */ + return bfwd->current_alist_element; + else + return assq_no_quit (symbol, buffer->local_var_alist); +} + +/* [Remember that the slot that mirrors CURRENT-VALUE in the + symbol-value-buffer-local of a per-buffer variable -- i.e. the + slot in CURRENT-BUFFER's local_var_alist, or the DEFAULT-VALUE + slot -- may be out of date.] + + Write out any cached value in buffer-local variable SYMBOL's + buffer-local structure, which is passed in as BFWD. +*/ + +static void +write_out_buffer_local_cache (Lisp_Object symbol, + struct symbol_value_buffer_local *bfwd) +{ + if (!NILP (bfwd->current_buffer)) + { + /* We pass 0 for BUFFER because only SYMVAL_CURRENT_BUFFER_FORWARD + uses it, and that type cannot be inside a symbol-value-buffer-local */ + Lisp_Object cval = do_symval_forwarding (bfwd->current_value, 0, 0); + if (NILP (bfwd->current_alist_element)) + /* current_value may be updated more recently than default_value */ + bfwd->default_value = cval; + else + Fsetcdr (bfwd->current_alist_element, cval); + } +} + +/* SYM is a buffer-local variable, and BFWD is its buffer-local structure. + Set up BFWD's cache for validity in buffer BUF. This assumes that + the cache is currently in a consistent state (this can include + not having any value cached, if BFWD->CURRENT_BUFFER is nil). + + If the cache is already set up for BUF, this function does nothing + at all. + + Otherwise, if SYM forwards out to a C variable, this also forwards + SYM's value in BUF out to the variable. Therefore, you generally + only want to call this when BUF is, or is about to become, the + current buffer. + + (Otherwise, you can just retrieve the value without changing the + cache, at the expense of slower retrieval.) +*/ + +static void +set_up_buffer_local_cache (Lisp_Object sym, + struct symbol_value_buffer_local *bfwd, + struct buffer *buf, + Lisp_Object new_alist_el, + int set_it_p) +{ + Lisp_Object new_val; + + if (!NILP (bfwd->current_buffer) + && buf == XBUFFER (bfwd->current_buffer)) + /* Cache is already set up. */ + return; + + /* Flush out the old cache. */ + write_out_buffer_local_cache (sym, bfwd); + + /* Retrieve the new alist element and new value. */ + if (NILP (new_alist_el) + && set_it_p) + new_alist_el = buffer_local_alist_element (buf, sym, bfwd); + + if (NILP (new_alist_el)) + new_val = bfwd->default_value; + else + new_val = Fcdr (new_alist_el); + + bfwd->current_alist_element = new_alist_el; + XSETBUFFER (bfwd->current_buffer, buf); + + /* Now store the value into the current-value slot. + We don't simply write it there, because the current-value + slot might be a forwarding pointer, in which case we need + to instead write the value into the C variable. + + We might also want to call a magic function. + + So instead, we call this function. */ + store_symval_forwarding (sym, bfwd->current_value, new_val); +} + + +void +kill_buffer_local_variables (struct buffer *buf) +{ + Lisp_Object prev = Qnil; + Lisp_Object alist; + + /* Any which are supposed to be permanent, + make local again, with the same values they had. */ + + for (alist = buf->local_var_alist; !NILP (alist); alist = XCDR (alist)) + { + Lisp_Object sym = XCAR (XCAR (alist)); + struct symbol_value_buffer_local *bfwd; + /* Variables with a symbol-value-varalias should not be here + (we should have forwarded past them) and there must be a + symbol-value-buffer-local. If there's a symbol-value-lisp-magic, + just forward past it; if the variable has a handler, it was + already called. */ + Lisp_Object value = fetch_value_maybe_past_magic (sym, Qt); + + assert (SYMBOL_VALUE_BUFFER_LOCAL_P (value)); + bfwd = XSYMBOL_VALUE_BUFFER_LOCAL (value); + + if (!NILP (Fget (sym, Qpermanent_local, Qnil))) + /* prev points to the last alist element that is still + staying around, so *only* update it now. This didn't + used to be the case; this bug has been around since + mly's rewrite two years ago! */ + prev = alist; + else + { + /* Really truly kill it. */ + if (!NILP (prev)) + XCDR (prev) = XCDR (alist); + else + buf->local_var_alist = XCDR (alist); + + /* We just effectively changed the value for this variable + in BUF. So: */ + + /* (1) If the cache is caching BUF, invalidate the cache. */ + if (!NILP (bfwd->current_buffer) && + buf == XBUFFER (bfwd->current_buffer)) + bfwd->current_buffer = Qnil; + + /* (2) If we changed the value in current_buffer and this + variable forwards to a C variable, we need to change the + value of the C variable. set_up_buffer_local_cache() + will do this. It doesn't hurt to do it whenever + BUF == current_buffer, so just go ahead and do that. */ + if (buf == current_buffer) + set_up_buffer_local_cache (sym, bfwd, buf, Qnil, 0); + } + } +} + +static Lisp_Object +find_symbol_value_1 (Lisp_Object sym, struct buffer *buf, + struct console *con, int swap_it_in, + Lisp_Object symcons, int set_it_p) +{ + Lisp_Object valcontents; + + retry: + valcontents = XSYMBOL (sym)->value; + + retry_2: + if (!SYMBOL_VALUE_MAGIC_P (valcontents)) + return valcontents; + + switch (XSYMBOL_VALUE_MAGIC_TYPE (valcontents)) + { + case SYMVAL_LISP_MAGIC: + /* #### kludge */ + valcontents = XSYMBOL_VALUE_LISP_MAGIC (valcontents)->shadowed; + /* semi-change-o */ + goto retry_2; + + case SYMVAL_VARALIAS: + sym = follow_varalias_pointers (sym, Qt /* #### kludge */); + symcons = Qnil; + /* presto change-o! */ + goto retry; + + case SYMVAL_BUFFER_LOCAL: + case SYMVAL_SOME_BUFFER_LOCAL: + { + struct symbol_value_buffer_local *bfwd + = XSYMBOL_VALUE_BUFFER_LOCAL (valcontents); + + if (swap_it_in) + { + set_up_buffer_local_cache (sym, bfwd, buf, symcons, set_it_p); + valcontents = bfwd->current_value; + } + else + { + if (!NILP (bfwd->current_buffer) && + buf == XBUFFER (bfwd->current_buffer)) + valcontents = bfwd->current_value; + else if (NILP (symcons)) + { + if (set_it_p) + valcontents = assq_no_quit (sym, buf->local_var_alist); + if (NILP (valcontents)) + valcontents = bfwd->default_value; + else + valcontents = XCDR (valcontents); + } + else + valcontents = XCDR (symcons); + } + break; + } + + default: + break; + } + return do_symval_forwarding (valcontents, buf, con); +} + + +/* Find the value of a symbol in BUFFER, returning Qunbound if it's not + bound. Note that it must not be possible to QUIT within this + function. */ + +Lisp_Object +symbol_value_in_buffer (Lisp_Object sym, Lisp_Object buffer) +{ + struct buffer *buf; + + CHECK_SYMBOL (sym); + + if (NILP (buffer)) + buf = current_buffer; + else + { + CHECK_BUFFER (buffer); + buf = XBUFFER (buffer); + } + + return find_symbol_value_1 (sym, buf, + /* If it bombs out at startup due to a + Lisp error, this may be nil. */ + CONSOLEP (Vselected_console) + ? XCONSOLE (Vselected_console) : 0, 0, Qnil, 1); +} + +static Lisp_Object +symbol_value_in_console (Lisp_Object sym, Lisp_Object console) +{ + CHECK_SYMBOL (sym); + + if (NILP (console)) + console = Vselected_console; + else + CHECK_CONSOLE (console); + + return find_symbol_value_1 (sym, current_buffer, XCONSOLE (console), 0, + Qnil, 1); +} + +/* Return the current value of SYM. The difference between this function + and calling symbol_value_in_buffer with a BUFFER of Qnil is that + this updates the CURRENT_VALUE slot of buffer-local variables to + point to the current buffer, while symbol_value_in_buffer doesn't. */ + +Lisp_Object +find_symbol_value (Lisp_Object sym) +{ + /* WARNING: This function can be called when current_buffer is 0 + and Vselected_console is Qnil, early in initialization. */ + struct console *con; + Lisp_Object valcontents; + + CHECK_SYMBOL (sym); + + valcontents = XSYMBOL (sym)->value; + if (!SYMBOL_VALUE_MAGIC_P (valcontents)) + return valcontents; + + if (CONSOLEP (Vselected_console)) + con = XCONSOLE (Vselected_console); + else + { + /* This can also get called while we're preparing to shutdown. + #### What should really happen in that case? Should we + actually fix things so we can't get here in that case? */ +#ifndef PDUMP + assert (!initialized || preparing_for_armageddon); +#endif + con = 0; + } + + return find_symbol_value_1 (sym, current_buffer, con, 1, Qnil, 1); +} + +/* This is an optimized function for quick lookup of buffer local symbols + by avoiding O(n) search. This will work when either: + a) We have already found the symbol e.g. by traversing local_var_alist. + or + b) We know that the symbol will not be found in the current buffer's + list of local variables. + In the former case, find_it_p is 1 and symbol_cons is the element from + local_var_alist. In the latter case, find_it_p is 0 and symbol_cons + is the symbol. + + This function is called from set_buffer_internal which does both of these + things. */ + +Lisp_Object +find_symbol_value_quickly (Lisp_Object symbol_cons, int find_it_p) +{ + /* WARNING: This function can be called when current_buffer is 0 + and Vselected_console is Qnil, early in initialization. */ + struct console *con; + Lisp_Object sym = find_it_p ? XCAR (symbol_cons) : symbol_cons; + + CHECK_SYMBOL (sym); + if (CONSOLEP (Vselected_console)) + con = XCONSOLE (Vselected_console); + else + { + /* This can also get called while we're preparing to shutdown. + #### What should really happen in that case? Should we + actually fix things so we can't get here in that case? */ +#ifndef PDUMP + assert (!initialized || preparing_for_armageddon); +#endif + con = 0; + } + + return find_symbol_value_1 (sym, current_buffer, con, 1, + find_it_p ? symbol_cons : Qnil, + find_it_p); +} + +DEFUN ("symbol-value", Fsymbol_value, 1, 1, 0, /* +Return SYMBOL's value. Error if that is void. +*/ + (symbol)) +{ + Lisp_Object val = find_symbol_value (symbol); + + if (UNBOUNDP (val)) + return Fsignal (Qvoid_variable, list1 (symbol)); + else + return val; +} + +DEFUN ("set", Fset, 2, 2, 0, /* +Set SYMBOL's value to NEWVAL, and return NEWVAL. +*/ + (symbol, newval)) +{ + REGISTER Lisp_Object valcontents; + struct Lisp_Symbol *sym; + /* remember, we're called by Fmakunbound() as well */ + + CHECK_SYMBOL (symbol); + + retry: + sym = XSYMBOL (symbol); + valcontents = sym->value; + + if (EQ (symbol, Qnil) || + EQ (symbol, Qt) || + SYMBOL_IS_KEYWORD (symbol)) + reject_constant_symbols (symbol, newval, 0, + UNBOUNDP (newval) ? Qmakunbound : Qset); + + if (!SYMBOL_VALUE_MAGIC_P (valcontents) || UNBOUNDP (valcontents)) + { + sym->value = newval; + return newval; + } + + reject_constant_symbols (symbol, newval, 0, + UNBOUNDP (newval) ? Qmakunbound : Qset); + + retry_2: + + switch (XSYMBOL_VALUE_MAGIC_TYPE (valcontents)) + { + case SYMVAL_LISP_MAGIC: + { + Lisp_Object retval; + + if (UNBOUNDP (newval)) + retval = maybe_call_magic_handler (symbol, Qmakunbound, 0); + else + retval = maybe_call_magic_handler (symbol, Qset, 1, newval); + if (!UNBOUNDP (retval)) + return newval; + valcontents = XSYMBOL_VALUE_LISP_MAGIC (valcontents)->shadowed; + /* semi-change-o */ + goto retry_2; + } + + case SYMVAL_VARALIAS: + symbol = follow_varalias_pointers (symbol, + UNBOUNDP (newval) + ? Qmakunbound : Qset); + /* presto change-o! */ + goto retry; + + case SYMVAL_FIXNUM_FORWARD: + case SYMVAL_BOOLEAN_FORWARD: + case SYMVAL_OBJECT_FORWARD: + case SYMVAL_DEFAULT_BUFFER_FORWARD: + case SYMVAL_DEFAULT_CONSOLE_FORWARD: + if (UNBOUNDP (newval)) + signal_error (Qerror, + list2 (build_string ("Cannot makunbound"), symbol)); + break; + + /* case SYMVAL_UNBOUND_MARKER: break; */ + + case SYMVAL_CURRENT_BUFFER_FORWARD: + { + CONST struct symbol_value_forward *fwd + = XSYMBOL_VALUE_FORWARD (valcontents); + int mask = XINT (*((Lisp_Object *) + symbol_value_forward_forward (fwd))); + if (mask > 0) + /* Setting this variable makes it buffer-local */ + current_buffer->local_var_flags |= mask; + break; + } + + case SYMVAL_SELECTED_CONSOLE_FORWARD: + { + CONST struct symbol_value_forward *fwd + = XSYMBOL_VALUE_FORWARD (valcontents); + int mask = XINT (*((Lisp_Object *) + symbol_value_forward_forward (fwd))); + if (mask > 0) + /* Setting this variable makes it console-local */ + XCONSOLE (Vselected_console)->local_var_flags |= mask; + break; + } + + case SYMVAL_BUFFER_LOCAL: + case SYMVAL_SOME_BUFFER_LOCAL: + { + /* If we want to examine or set the value and + CURRENT-BUFFER is current, we just examine or set + CURRENT-VALUE. If CURRENT-BUFFER is not current, we + store the current CURRENT-VALUE value into + CURRENT-ALIST- ELEMENT, then find the appropriate alist + element for the buffer now current and set up + CURRENT-ALIST-ELEMENT. Then we set CURRENT-VALUE out + of that element, and store into CURRENT-BUFFER. + + If we are setting the variable and the current buffer does + not have an alist entry for this variable, an alist entry is + created. + + Note that CURRENT-VALUE can be a forwarding pointer. + Each time it is examined or set, forwarding must be + done. */ + struct symbol_value_buffer_local *bfwd + = XSYMBOL_VALUE_BUFFER_LOCAL (valcontents); + int some_buffer_local_p = + (bfwd->magic.type == SYMVAL_SOME_BUFFER_LOCAL); + /* What value are we caching right now? */ + Lisp_Object aelt = bfwd->current_alist_element; + + if (!NILP (bfwd->current_buffer) && + current_buffer == XBUFFER (bfwd->current_buffer) + && ((some_buffer_local_p) + ? 1 /* doesn't automatically become local */ + : !NILP (aelt) /* already local */ + )) + { + /* Cache is valid */ + valcontents = bfwd->current_value; + } + else + { + /* If the current buffer is not the buffer whose binding is + currently cached, or if it's a SYMVAL_BUFFER_LOCAL and + we're looking at the default value, the cache is invalid; we + need to write it out, and find the new CURRENT-ALIST-ELEMENT + */ + + /* Write out the cached value for the old buffer; copy it + back to its alist element. This works if the current + buffer only sees the default value, too. */ + write_out_buffer_local_cache (symbol, bfwd); + + /* Find the new value for CURRENT-ALIST-ELEMENT. */ + aelt = buffer_local_alist_element (current_buffer, symbol, bfwd); + if (NILP (aelt)) + { + /* This buffer is still seeing the default value. */ + if (!some_buffer_local_p) + { + /* If it's a SYMVAL_BUFFER_LOCAL, give this buffer a + new assoc for a local value and set + CURRENT-ALIST-ELEMENT to point to that. */ + aelt = + do_symval_forwarding (bfwd->current_value, + current_buffer, + XCONSOLE (Vselected_console)); + aelt = Fcons (symbol, aelt); + current_buffer->local_var_alist + = Fcons (aelt, current_buffer->local_var_alist); + } + else + { + /* If the variable is a SYMVAL_SOME_BUFFER_LOCAL, + we're currently seeing the default value. */ + ; + } + } + /* Cache the new buffer's assoc in CURRENT-ALIST-ELEMENT. */ + bfwd->current_alist_element = aelt; + /* Set BUFFER, now that CURRENT-ALIST-ELEMENT is accurate. */ + XSETBUFFER (bfwd->current_buffer, current_buffer); + valcontents = bfwd->current_value; + } + break; + } + default: + abort (); + } + store_symval_forwarding (symbol, valcontents, newval); + + return newval; +} + + +/* Access or set a buffer-local symbol's default value. */ + +/* Return the default value of SYM, but don't check for voidness. + Return Qunbound if it is void. */ + +static Lisp_Object +default_value (Lisp_Object sym) +{ + Lisp_Object valcontents; + + CHECK_SYMBOL (sym); + + retry: + valcontents = XSYMBOL (sym)->value; + + retry_2: + if (!SYMBOL_VALUE_MAGIC_P (valcontents)) + return valcontents; + + switch (XSYMBOL_VALUE_MAGIC_TYPE (valcontents)) + { + case SYMVAL_LISP_MAGIC: + /* #### kludge */ + valcontents = XSYMBOL_VALUE_LISP_MAGIC (valcontents)->shadowed; + /* semi-change-o */ + goto retry_2; + + case SYMVAL_VARALIAS: + sym = follow_varalias_pointers (sym, Qt /* #### kludge */); + /* presto change-o! */ + goto retry; + + case SYMVAL_UNBOUND_MARKER: + return valcontents; + + case SYMVAL_CURRENT_BUFFER_FORWARD: + { + CONST struct symbol_value_forward *fwd + = XSYMBOL_VALUE_FORWARD (valcontents); + return (*((Lisp_Object *)((char *) XBUFFER (Vbuffer_defaults) + + ((char *)symbol_value_forward_forward (fwd) + - (char *)&buffer_local_flags)))); + } + + case SYMVAL_SELECTED_CONSOLE_FORWARD: + { + CONST struct symbol_value_forward *fwd + = XSYMBOL_VALUE_FORWARD (valcontents); + return (*((Lisp_Object *)((char *) XCONSOLE (Vconsole_defaults) + + ((char *)symbol_value_forward_forward (fwd) + - (char *)&console_local_flags)))); + } + + case SYMVAL_BUFFER_LOCAL: + case SYMVAL_SOME_BUFFER_LOCAL: + { + struct symbol_value_buffer_local *bfwd = + XSYMBOL_VALUE_BUFFER_LOCAL (valcontents); + + /* Handle user-created local variables. */ + /* If var is set up for a buffer that lacks a local value for it, + the current value is nominally the default value. + But the current value slot may be more up to date, since + ordinary setq stores just that slot. So use that. */ + if (NILP (bfwd->current_alist_element)) + return do_symval_forwarding (bfwd->current_value, current_buffer, + XCONSOLE (Vselected_console)); + else + return bfwd->default_value; + } + default: + /* For other variables, get the current value. */ + return do_symval_forwarding (valcontents, current_buffer, + XCONSOLE (Vselected_console)); + } + + RETURN_NOT_REACHED (Qnil) /* suppress compiler warning */ +} + +DEFUN ("default-boundp", Fdefault_boundp, 1, 1, 0, /* +Return t if SYMBOL has a non-void default value. +This is the value that is seen in buffers that do not have their own values +for this variable. +*/ + (symbol)) +{ + return UNBOUNDP (default_value (symbol)) ? Qnil : Qt; +} + +DEFUN ("default-value", Fdefault_value, 1, 1, 0, /* +Return SYMBOL's default value. +This is the value that is seen in buffers that do not have their own values +for this variable. The default value is meaningful for variables with +local bindings in certain buffers. +*/ + (symbol)) +{ + Lisp_Object value = default_value (symbol); + + return UNBOUNDP (value) ? Fsignal (Qvoid_variable, list1 (symbol)) : value; +} + +DEFUN ("set-default", Fset_default, 2, 2, 0, /* +Set SYMBOL's default value to VAL. SYMBOL and VAL are evaluated. +The default value is seen in buffers that do not have their own values +for this variable. +*/ + (symbol, value)) +{ + Lisp_Object valcontents; + + CHECK_SYMBOL (symbol); + + retry: + valcontents = XSYMBOL (symbol)->value; + + retry_2: + if (!SYMBOL_VALUE_MAGIC_P (valcontents)) + return Fset (symbol, value); + + switch (XSYMBOL_VALUE_MAGIC_TYPE (valcontents)) + { + case SYMVAL_LISP_MAGIC: + RETURN_IF_NOT_UNBOUND (maybe_call_magic_handler (symbol, Qset_default, 1, + value)); + valcontents = XSYMBOL_VALUE_LISP_MAGIC (valcontents)->shadowed; + /* semi-change-o */ + goto retry_2; + + case SYMVAL_VARALIAS: + symbol = follow_varalias_pointers (symbol, Qset_default); + /* presto change-o! */ + goto retry; + + case SYMVAL_CURRENT_BUFFER_FORWARD: + set_default_buffer_slot_variable (symbol, value); + return value; + + case SYMVAL_SELECTED_CONSOLE_FORWARD: + set_default_console_slot_variable (symbol, value); + return value; + + case SYMVAL_BUFFER_LOCAL: + case SYMVAL_SOME_BUFFER_LOCAL: + { + /* Store new value into the DEFAULT-VALUE slot */ + struct symbol_value_buffer_local *bfwd + = XSYMBOL_VALUE_BUFFER_LOCAL (valcontents); + + bfwd->default_value = value; + /* If current-buffer doesn't shadow default_value, + * we must set the CURRENT-VALUE slot too */ + if (NILP (bfwd->current_alist_element)) + store_symval_forwarding (symbol, bfwd->current_value, value); + return value; + } + + default: + return Fset (symbol, value); + } +} + +DEFUN ("setq-default", Fsetq_default, 0, UNEVALLED, 0, /* +Set the default value of variable SYMBOL to VALUE. +SYMBOL, the variable name, is literal (not evaluated); +VALUE is an expression and it is evaluated. +The default value of a variable is seen in buffers +that do not have their own values for the variable. + +More generally, you can use multiple variables and values, as in + (setq-default SYMBOL VALUE SYMBOL VALUE...) +This sets each SYMBOL's default value to the corresponding VALUE. +The VALUE for the Nth SYMBOL can refer to the new default values +of previous SYMBOLs. +*/ + (args)) +{ + /* This function can GC */ + Lisp_Object symbol, tail, val = Qnil; + int nargs; + struct gcpro gcpro1; + + GET_LIST_LENGTH (args, nargs); + + if (nargs & 1) /* Odd number of arguments? */ + Fsignal (Qwrong_number_of_arguments, + list2 (Qsetq_default, make_int (nargs))); + + GCPRO1 (val); + + PROPERTY_LIST_LOOP (tail, symbol, val, args) + { + val = Feval (val); + Fset_default (symbol, val); + } + + UNGCPRO; + return val; +} + +/* Lisp functions for creating and removing buffer-local variables. */ + +DEFUN ("make-variable-buffer-local", Fmake_variable_buffer_local, 1, 1, + "vMake Variable Buffer Local: ", /* +Make VARIABLE have a separate value for each buffer. +At any time, the value for the current buffer is in effect. +There is also a default value which is seen in any buffer which has not yet +set its own value. +Using `set' or `setq' to set the variable causes it to have a separate value +for the current buffer if it was previously using the default value. +The function `default-value' gets the default value and `set-default' +sets it. +*/ + (variable)) +{ + Lisp_Object valcontents; + + CHECK_SYMBOL (variable); + + retry: + verify_ok_for_buffer_local (variable, Qmake_variable_buffer_local); + + valcontents = XSYMBOL (variable)->value; + + retry_2: + if (SYMBOL_VALUE_MAGIC_P (valcontents)) + { + switch (XSYMBOL_VALUE_MAGIC_TYPE (valcontents)) + { + case SYMVAL_LISP_MAGIC: + if (!UNBOUNDP (maybe_call_magic_handler + (variable, Qmake_variable_buffer_local, 0))) + return variable; + valcontents = XSYMBOL_VALUE_LISP_MAGIC (valcontents)->shadowed; + /* semi-change-o */ + goto retry_2; + + case SYMVAL_VARALIAS: + variable = follow_varalias_pointers (variable, + Qmake_variable_buffer_local); + /* presto change-o! */ + goto retry; + + case SYMVAL_FIXNUM_FORWARD: + case SYMVAL_BOOLEAN_FORWARD: + case SYMVAL_OBJECT_FORWARD: + case SYMVAL_UNBOUND_MARKER: + break; + + case SYMVAL_CURRENT_BUFFER_FORWARD: + case SYMVAL_BUFFER_LOCAL: + /* Already per-each-buffer */ + return variable; + + case SYMVAL_SOME_BUFFER_LOCAL: + /* Transmogrify */ + XSYMBOL_VALUE_BUFFER_LOCAL (valcontents)->magic.type = + SYMVAL_BUFFER_LOCAL; + return variable; + + default: + abort (); + } + } + + { + struct symbol_value_buffer_local *bfwd + = alloc_lcrecord_type (struct symbol_value_buffer_local, + &lrecord_symbol_value_buffer_local); + Lisp_Object foo; + bfwd->magic.type = SYMVAL_BUFFER_LOCAL; + + bfwd->default_value = find_symbol_value (variable); + bfwd->current_value = valcontents; + bfwd->current_alist_element = Qnil; + bfwd->current_buffer = Fcurrent_buffer (); + XSETSYMBOL_VALUE_MAGIC (foo, bfwd); + *value_slot_past_magic (variable) = foo; +#if 1 /* #### Yuck! FSFmacs bug-compatibility*/ + /* This sets the default-value of any make-variable-buffer-local to nil. + That just sucks. User can just use setq-default to effect that, + but there's no way to do makunbound-default to undo this lossage. */ + if (UNBOUNDP (valcontents)) + bfwd->default_value = Qnil; +#endif +#if 0 /* #### Yuck! */ + /* This sets the value to nil in this buffer. + User could use (setq variable nil) to do this. + It isn't as egregious to do this automatically + as it is to do so to the default-value, but it's + still really dubious. */ + if (UNBOUNDP (valcontents)) + Fset (variable, Qnil); +#endif + return variable; + } +} + +DEFUN ("make-local-variable", Fmake_local_variable, 1, 1, + "vMake Local Variable: ", /* +Make VARIABLE have a separate value in the current buffer. +Other buffers will continue to share a common default value. +\(The buffer-local value of VARIABLE starts out as the same value +VARIABLE previously had. If VARIABLE was void, it remains void.) +See also `make-variable-buffer-local'. + +If the variable is already arranged to become local when set, +this function causes a local value to exist for this buffer, +just as setting the variable would do. + +Do not use `make-local-variable' to make a hook variable buffer-local. +Use `make-local-hook' instead. +*/ + (variable)) +{ + Lisp_Object valcontents; + struct symbol_value_buffer_local *bfwd; + + CHECK_SYMBOL (variable); + + retry: + verify_ok_for_buffer_local (variable, Qmake_local_variable); + + valcontents = XSYMBOL (variable)->value; + + retry_2: + if (SYMBOL_VALUE_MAGIC_P (valcontents)) + { + switch (XSYMBOL_VALUE_MAGIC_TYPE (valcontents)) + { + case SYMVAL_LISP_MAGIC: + if (!UNBOUNDP (maybe_call_magic_handler + (variable, Qmake_local_variable, 0))) + return variable; + valcontents = XSYMBOL_VALUE_LISP_MAGIC (valcontents)->shadowed; + /* semi-change-o */ + goto retry_2; + + case SYMVAL_VARALIAS: + variable = follow_varalias_pointers (variable, Qmake_local_variable); + /* presto change-o! */ + goto retry; + + case SYMVAL_FIXNUM_FORWARD: + case SYMVAL_BOOLEAN_FORWARD: + case SYMVAL_OBJECT_FORWARD: + case SYMVAL_UNBOUND_MARKER: + break; + + case SYMVAL_BUFFER_LOCAL: + case SYMVAL_CURRENT_BUFFER_FORWARD: + { + /* Make sure the symbol has a local value in this particular + buffer, by setting it to the same value it already has. */ + Fset (variable, find_symbol_value (variable)); + return variable; + } + + case SYMVAL_SOME_BUFFER_LOCAL: + { + if (!NILP (buffer_local_alist_element (current_buffer, + variable, + (XSYMBOL_VALUE_BUFFER_LOCAL + (valcontents))))) + goto already_local_to_current_buffer; + else + goto already_local_to_some_other_buffer; + } + + default: + abort (); + } + } + + /* Make sure variable is set up to hold per-buffer values */ + bfwd = alloc_lcrecord_type (struct symbol_value_buffer_local, + &lrecord_symbol_value_buffer_local); + bfwd->magic.type = SYMVAL_SOME_BUFFER_LOCAL; + + bfwd->current_buffer = Qnil; + bfwd->current_alist_element = Qnil; + bfwd->current_value = valcontents; + /* passing 0 is OK because this should never be a + SYMVAL_CURRENT_BUFFER_FORWARD or SYMVAL_SELECTED_CONSOLE_FORWARD + variable. */ + bfwd->default_value = do_symval_forwarding (valcontents, 0, 0); + +#if 0 + if (UNBOUNDP (bfwd->default_value)) + bfwd->default_value = Qnil; /* Yuck! */ +#endif + + XSETSYMBOL_VALUE_MAGIC (valcontents, bfwd); + *value_slot_past_magic (variable) = valcontents; + + already_local_to_some_other_buffer: + + /* Make sure this buffer has its own value of variable */ + bfwd = XSYMBOL_VALUE_BUFFER_LOCAL (valcontents); + + if (UNBOUNDP (bfwd->default_value)) + { + /* If default value is unbound, set local value to nil. */ + XSETBUFFER (bfwd->current_buffer, current_buffer); + bfwd->current_alist_element = Fcons (variable, Qnil); + current_buffer->local_var_alist = + Fcons (bfwd->current_alist_element, current_buffer->local_var_alist); + store_symval_forwarding (variable, bfwd->current_value, Qnil); + return variable; + } + + current_buffer->local_var_alist + = Fcons (Fcons (variable, bfwd->default_value), + current_buffer->local_var_alist); + + /* Make sure symbol does not think it is set up for this buffer; + force it to look once again for this buffer's value */ + if (!NILP (bfwd->current_buffer) && + current_buffer == XBUFFER (bfwd->current_buffer)) + bfwd->current_buffer = Qnil; + + already_local_to_current_buffer: + + /* If the symbol forwards into a C variable, then swap in the + variable for this buffer immediately. If C code modifies the + variable before we swap in, then that new value will clobber the + default value the next time we swap. */ + bfwd = XSYMBOL_VALUE_BUFFER_LOCAL (valcontents); + if (SYMBOL_VALUE_MAGIC_P (bfwd->current_value)) + { + switch (XSYMBOL_VALUE_MAGIC_TYPE (bfwd->current_value)) + { + case SYMVAL_FIXNUM_FORWARD: + case SYMVAL_BOOLEAN_FORWARD: + case SYMVAL_OBJECT_FORWARD: + case SYMVAL_DEFAULT_BUFFER_FORWARD: + set_up_buffer_local_cache (variable, bfwd, current_buffer, Qnil, 1); + break; + + case SYMVAL_UNBOUND_MARKER: + case SYMVAL_CURRENT_BUFFER_FORWARD: + break; + + default: + abort (); + } + } + + return variable; +} + +DEFUN ("kill-local-variable", Fkill_local_variable, 1, 1, + "vKill Local Variable: ", /* +Make VARIABLE no longer have a separate value in the current buffer. +From now on the default value will apply in this buffer. +*/ + (variable)) +{ + Lisp_Object valcontents; + + CHECK_SYMBOL (variable); + + retry: + valcontents = XSYMBOL (variable)->value; + + retry_2: + if (!SYMBOL_VALUE_MAGIC_P (valcontents)) + return variable; + + switch (XSYMBOL_VALUE_MAGIC_TYPE (valcontents)) + { + case SYMVAL_LISP_MAGIC: + if (!UNBOUNDP (maybe_call_magic_handler + (variable, Qkill_local_variable, 0))) + return variable; + valcontents = XSYMBOL_VALUE_LISP_MAGIC (valcontents)->shadowed; + /* semi-change-o */ + goto retry_2; + + case SYMVAL_VARALIAS: + variable = follow_varalias_pointers (variable, Qkill_local_variable); + /* presto change-o! */ + goto retry; + + case SYMVAL_CURRENT_BUFFER_FORWARD: + { + CONST struct symbol_value_forward *fwd + = XSYMBOL_VALUE_FORWARD (valcontents); + int offset = ((char *) symbol_value_forward_forward (fwd) + - (char *) &buffer_local_flags); + int mask = + XINT (*((Lisp_Object *) symbol_value_forward_forward (fwd))); + + if (mask > 0) + { + int (*magicfun) (Lisp_Object sym, Lisp_Object *val, + Lisp_Object in_object, int flags) = + symbol_value_forward_magicfun (fwd); + Lisp_Object oldval = * (Lisp_Object *) + (offset + (char *) XBUFFER (Vbuffer_defaults)); + if (magicfun) + (magicfun) (variable, &oldval, make_buffer (current_buffer), 0); + *(Lisp_Object *) (offset + (char *) current_buffer) + = oldval; + current_buffer->local_var_flags &= ~mask; + } + return variable; + } + + case SYMVAL_BUFFER_LOCAL: + case SYMVAL_SOME_BUFFER_LOCAL: + { + /* Get rid of this buffer's alist element, if any */ + struct symbol_value_buffer_local *bfwd + = XSYMBOL_VALUE_BUFFER_LOCAL (valcontents); + Lisp_Object alist = current_buffer->local_var_alist; + Lisp_Object alist_element + = buffer_local_alist_element (current_buffer, variable, bfwd); + + if (!NILP (alist_element)) + current_buffer->local_var_alist = Fdelq (alist_element, alist); + + /* Make sure symbol does not think it is set up for this buffer; + force it to look once again for this buffer's value */ + if (!NILP (bfwd->current_buffer) && + current_buffer == XBUFFER (bfwd->current_buffer)) + bfwd->current_buffer = Qnil; + + /* We just changed the value in the current_buffer. If this + variable forwards to a C variable, we need to change the + value of the C variable. set_up_buffer_local_cache() + will do this. It doesn't hurt to do it always, + so just go ahead and do that. */ + set_up_buffer_local_cache (variable, bfwd, current_buffer, Qnil, 1); + } + return variable; + + default: + return variable; + } + RETURN_NOT_REACHED(Qnil) /* suppress compiler warning */ +} + + +DEFUN ("kill-console-local-variable", Fkill_console_local_variable, 1, 1, + "vKill Console Local Variable: ", /* +Make VARIABLE no longer have a separate value in the selected console. +From now on the default value will apply in this console. +*/ + (variable)) +{ + Lisp_Object valcontents; + + CHECK_SYMBOL (variable); + + retry: + valcontents = XSYMBOL (variable)->value; + + retry_2: + if (!SYMBOL_VALUE_MAGIC_P (valcontents)) + return variable; + + switch (XSYMBOL_VALUE_MAGIC_TYPE (valcontents)) + { + case SYMVAL_LISP_MAGIC: + if (!UNBOUNDP (maybe_call_magic_handler + (variable, Qkill_console_local_variable, 0))) + return variable; + valcontents = XSYMBOL_VALUE_LISP_MAGIC (valcontents)->shadowed; + /* semi-change-o */ + goto retry_2; + + case SYMVAL_VARALIAS: + variable = follow_varalias_pointers (variable, + Qkill_console_local_variable); + /* presto change-o! */ + goto retry; + + case SYMVAL_SELECTED_CONSOLE_FORWARD: + { + CONST struct symbol_value_forward *fwd + = XSYMBOL_VALUE_FORWARD (valcontents); + int offset = ((char *) symbol_value_forward_forward (fwd) + - (char *) &console_local_flags); + int mask = + XINT (*((Lisp_Object *) symbol_value_forward_forward (fwd))); + + if (mask > 0) + { + int (*magicfun) (Lisp_Object sym, Lisp_Object *val, + Lisp_Object in_object, int flags) = + symbol_value_forward_magicfun (fwd); + Lisp_Object oldval = * (Lisp_Object *) + (offset + (char *) XCONSOLE (Vconsole_defaults)); + if (magicfun) + magicfun (variable, &oldval, Vselected_console, 0); + *(Lisp_Object *) (offset + (char *) XCONSOLE (Vselected_console)) + = oldval; + XCONSOLE (Vselected_console)->local_var_flags &= ~mask; + } + return variable; + } + + default: + return variable; + } +} + +/* Used by specbind to determine what effects it might have. Returns: + * 0 if symbol isn't buffer-local, and wouldn't be after it is set + * <0 if symbol isn't presently buffer-local, but set would make it so + * >0 if symbol is presently buffer-local + */ +int +symbol_value_buffer_local_info (Lisp_Object symbol, struct buffer *buffer) +{ + Lisp_Object valcontents; + + retry: + valcontents = XSYMBOL (symbol)->value; + + retry_2: + if (SYMBOL_VALUE_MAGIC_P (valcontents)) + { + switch (XSYMBOL_VALUE_MAGIC_TYPE (valcontents)) + { + case SYMVAL_LISP_MAGIC: + /* #### kludge */ + valcontents = XSYMBOL_VALUE_LISP_MAGIC (valcontents)->shadowed; + /* semi-change-o */ + goto retry_2; + + case SYMVAL_VARALIAS: + symbol = follow_varalias_pointers (symbol, Qt /* #### kludge */); + /* presto change-o! */ + goto retry; + + case SYMVAL_CURRENT_BUFFER_FORWARD: + { + CONST struct symbol_value_forward *fwd + = XSYMBOL_VALUE_FORWARD (valcontents); + int mask = XINT (*((Lisp_Object *) + symbol_value_forward_forward (fwd))); + if ((mask <= 0) || (buffer && (buffer->local_var_flags & mask))) + /* Already buffer-local */ + return 1; + else + /* Would be buffer-local after set */ + return -1; + } + case SYMVAL_BUFFER_LOCAL: + case SYMVAL_SOME_BUFFER_LOCAL: + { + struct symbol_value_buffer_local *bfwd + = XSYMBOL_VALUE_BUFFER_LOCAL (valcontents); + if (buffer + && !NILP (buffer_local_alist_element (buffer, symbol, bfwd))) + return 1; + else + /* Automatically becomes local when set */ + return bfwd->magic.type == SYMVAL_BUFFER_LOCAL ? -1 : 0; + } + default: + return 0; + } + } + return 0; +} + + +DEFUN ("symbol-value-in-buffer", Fsymbol_value_in_buffer, 2, 3, 0, /* +Return the value of SYMBOL in BUFFER, or UNBOUND-VALUE if it is unbound. +*/ + (symbol, buffer, unbound_value)) +{ + Lisp_Object value; + CHECK_SYMBOL (symbol); + CHECK_BUFFER (buffer); + value = symbol_value_in_buffer (symbol, buffer); + return UNBOUNDP (value) ? unbound_value : value; +} + +DEFUN ("symbol-value-in-console", Fsymbol_value_in_console, 2, 3, 0, /* +Return the value of SYMBOL in CONSOLE, or UNBOUND-VALUE if it is unbound. +*/ + (symbol, console, unbound_value)) +{ + Lisp_Object value; + CHECK_SYMBOL (symbol); + CHECK_CONSOLE (console); + value = symbol_value_in_console (symbol, console); + return UNBOUNDP (value) ? unbound_value : value; +} + +DEFUN ("built-in-variable-type", Fbuilt_in_variable_type, 1, 1, 0, /* +If SYMBOL is a built-in variable, return info about this; else return nil. +The returned info will be a symbol, one of + +`object' A simple built-in variable. +`const-object' Same, but cannot be set. +`integer' A built-in integer variable. +`const-integer' Same, but cannot be set. +`boolean' A built-in boolean variable. +`const-boolean' Same, but cannot be set. +`const-specifier' Always contains a specifier; e.g. `has-modeline-p'. +`current-buffer' A built-in buffer-local variable. +`const-current-buffer' Same, but cannot be set. +`default-buffer' Forwards to the default value of a built-in + buffer-local variable. +`selected-console' A built-in console-local variable. +`const-selected-console' Same, but cannot be set. +`default-console' Forwards to the default value of a built-in + console-local variable. +*/ + (symbol)) +{ + REGISTER Lisp_Object valcontents; + + CHECK_SYMBOL (symbol); + + retry: + valcontents = XSYMBOL (symbol)->value; + + retry_2: + if (!SYMBOL_VALUE_MAGIC_P (valcontents)) + return Qnil; + + switch (XSYMBOL_VALUE_MAGIC_TYPE (valcontents)) + { + case SYMVAL_LISP_MAGIC: + valcontents = XSYMBOL_VALUE_LISP_MAGIC (valcontents)->shadowed; + /* semi-change-o */ + goto retry_2; + + case SYMVAL_VARALIAS: + symbol = follow_varalias_pointers (symbol, Qt); + /* presto change-o! */ + goto retry; + + case SYMVAL_BUFFER_LOCAL: + case SYMVAL_SOME_BUFFER_LOCAL: + valcontents = + XSYMBOL_VALUE_BUFFER_LOCAL (valcontents)->current_value; + /* semi-change-o */ + goto retry_2; + + case SYMVAL_FIXNUM_FORWARD: return Qinteger; + case SYMVAL_CONST_FIXNUM_FORWARD: return Qconst_integer; + case SYMVAL_BOOLEAN_FORWARD: return Qboolean; + case SYMVAL_CONST_BOOLEAN_FORWARD: return Qconst_boolean; + case SYMVAL_OBJECT_FORWARD: return Qobject; + case SYMVAL_CONST_OBJECT_FORWARD: return Qconst_object; + case SYMVAL_CONST_SPECIFIER_FORWARD: return Qconst_specifier; + case SYMVAL_DEFAULT_BUFFER_FORWARD: return Qdefault_buffer; + case SYMVAL_CURRENT_BUFFER_FORWARD: return Qcurrent_buffer; + case SYMVAL_CONST_CURRENT_BUFFER_FORWARD: return Qconst_current_buffer; + case SYMVAL_DEFAULT_CONSOLE_FORWARD: return Qdefault_console; + case SYMVAL_SELECTED_CONSOLE_FORWARD: return Qselected_console; + case SYMVAL_CONST_SELECTED_CONSOLE_FORWARD: return Qconst_selected_console; + case SYMVAL_UNBOUND_MARKER: return Qnil; + + default: + abort (); return Qnil; + } +} + + +DEFUN ("local-variable-p", Flocal_variable_p, 2, 3, 0, /* +Return t if SYMBOL's value is local to BUFFER. +If optional third arg AFTER-SET is true, return t if SYMBOL would be +buffer-local after it is set, regardless of whether it is so presently. +A nil value for BUFFER is *not* the same as (current-buffer), but means +"no buffer". Specifically: + +-- If BUFFER is nil and AFTER-SET is nil, a return value of t indicates that + the variable is one of the special built-in variables that is always + buffer-local. (This includes `buffer-file-name', `buffer-read-only', + `buffer-undo-list', and others.) + +-- If BUFFER is nil and AFTER-SET is t, a return value of t indicates that + the variable has had `make-variable-buffer-local' applied to it. +*/ + (symbol, buffer, after_set)) +{ + int local_info; + + CHECK_SYMBOL (symbol); + if (!NILP (buffer)) + { + buffer = get_buffer (buffer, 1); + local_info = symbol_value_buffer_local_info (symbol, XBUFFER (buffer)); + } + else + { + local_info = symbol_value_buffer_local_info (symbol, 0); + } + + if (NILP (after_set)) + return local_info > 0 ? Qt : Qnil; + else + return local_info != 0 ? Qt : Qnil; +} + + +/* +I've gone ahead and partially implemented this because it's +super-useful for dealing with the compatibility problems in supporting +the old pointer-shape variables, and preventing people from `setq'ing +the new variables. Any other way of handling this problem is way +ugly, likely to be slow, and generally not something I want to waste +my time worrying about. + +The interface and/or function name is sure to change before this +gets into its final form. I currently like the way everything is +set up and it has all the features I want it to have, except for +one: I really want to be able to have multiple nested handlers, +to implement an `advice'-like capability. This would allow, +for example, a clean way of implementing `debug-if-set' or +`debug-if-referenced' and such. + +NOTE NOTE NOTE NOTE NOTE NOTE NOTE: +************************************************************ +**Only** the `set-value', `make-unbound', and `make-local' +handler types are currently implemented. Implementing the +get-value and bound-predicate handlers is somewhat tricky +because there are lots of subfunctions (e.g. find_symbol_value()). +find_symbol_value(), in fact, is called from outside of +this module. You'd have to have it do this: + +-- check for a `bound-predicate' handler, call that if so; + if it returns nil, return Qunbound +-- check for a `get-value' handler and call it and return + that value + +It gets even trickier when you have to deal with +sub-subfunctions like find_symbol_value_1(), and esp. +when you have to properly handle variable aliases, which +can lead to lots of tricky situations. So I've just +punted on this, since the interface isn't officially +exported and we can get by with just a `set-value' +handler. + +Actions in unimplemented handler types will correctly +ignore any handlers, and will not fuck anything up or +go awry. + +WARNING WARNING: If you do go and implement another +type of handler, make *sure* to change +would_be_magic_handled() so it knows about this, +or dire things could result. +************************************************************ +NOTE NOTE NOTE NOTE NOTE NOTE NOTE + +Real documentation is as follows. + +Set a magic handler for VARIABLE. +This allows you to specify arbitrary behavior that results from +accessing or setting a variable. For example, retrieving the +variable's value might actually retrieve the first element off of +a list stored in another variable, and setting the variable's value +might add an element to the front of that list. (This is how the +obsolete variable `unread-command-event' is implemented.) + +In general it is NOT good programming practice to use magic variables +in a new package that you are designing. If you feel the need to +do this, it's almost certainly a sign that you should be using a +function instead of a variable. This facility is provided to allow +a package to support obsolete variables and provide compatibility +with similar packages with different variable names and semantics. +By using magic handlers, you can cleanly provide obsoleteness and +compatibility support and separate this support from the core +routines in a package. + +VARIABLE should be a symbol naming the variable for which the +magic behavior is provided. HANDLER-TYPE is a symbol specifying +which behavior is being controlled, and HANDLER is the function +that will be called to control this behavior. HARG is a +value that will be passed to HANDLER but is otherwise +uninterpreted. KEEP-EXISTING specifies what to do with existing +handlers of the same type; nil means "erase them all", t means +"keep them but insert at the beginning", the list (t) means +"keep them but insert at the end", a function means "keep +them but insert before the specified function", a list containing +a function means "keep them but insert after the specified +function". + +You can specify magic behavior for any type of variable at all, +and for any handler types that are unspecified, the standard +behavior applies. This allows you, for example, to use +`defvaralias' in conjunction with this function. (For that +matter, `defvaralias' could be implemented using this function.) + +The behaviors that can be specified in HANDLER-TYPE are + +get-value (SYM ARGS FUN HARG HANDLERS) + This means that one of the functions `symbol-value', + `default-value', `symbol-value-in-buffer', or + `symbol-value-in-console' was called on SYM. + +set-value (SYM ARGS FUN HARG HANDLERS) + This means that one of the functions `set' or `set-default' + was called on SYM. + +bound-predicate (SYM ARGS FUN HARG HANDLERS) + This means that one of the functions `boundp', `globally-boundp', + or `default-boundp' was called on SYM. + +make-unbound (SYM ARGS FUN HARG HANDLERS) + This means that the function `makunbound' was called on SYM. + +local-predicate (SYM ARGS FUN HARG HANDLERS) + This means that the function `local-variable-p' was called + on SYM. + +make-local (SYM ARGS FUN HARG HANDLERS) + This means that one of the functions `make-local-variable', + `make-variable-buffer-local', `kill-local-variable', + or `kill-console-local-variable' was called on SYM. + +The meanings of the arguments are as follows: + + SYM is the symbol on which the function was called, and is always + the first argument to the function. + + ARGS are the remaining arguments in the original call (i.e. all + but the first). In the case of `set-value' in particular, + the first element of ARGS is the value to which the variable + is being set. In some cases, ARGS is sanitized from what was + actually given. For example, whenever `nil' is passed to an + argument and it means `current-buffer', the current buffer is + substituted instead. + + FUN is a symbol indicating which function is being called. + For many of the functions, you can determine the corresponding + function of a different class using + `symbol-function-corresponding-function'. + + HARG is the argument that was given in the call + to `set-symbol-value-handler' for SYM and HANDLER-TYPE. + + HANDLERS is a structure containing the remaining handlers + for the variable; to call one of them, use + `chain-to-symbol-value-handler'. + +NOTE: You may *not* modify the list in ARGS, and if you want to +keep it around after the handler function exits, you must make +a copy using `copy-sequence'. (Same caveats for HANDLERS also.) +*/ + +static enum lisp_magic_handler +decode_magic_handler_type (Lisp_Object symbol) +{ + if (EQ (symbol, Qget_value)) return MAGIC_HANDLER_GET_VALUE; + if (EQ (symbol, Qset_value)) return MAGIC_HANDLER_SET_VALUE; + if (EQ (symbol, Qbound_predicate)) return MAGIC_HANDLER_BOUND_PREDICATE; + if (EQ (symbol, Qmake_unbound)) return MAGIC_HANDLER_MAKE_UNBOUND; + if (EQ (symbol, Qlocal_predicate)) return MAGIC_HANDLER_LOCAL_PREDICATE; + if (EQ (symbol, Qmake_local)) return MAGIC_HANDLER_MAKE_LOCAL; + + signal_simple_error ("Unrecognized symbol value handler type", symbol); + abort (); + return MAGIC_HANDLER_MAX; +} + +static enum lisp_magic_handler +handler_type_from_function_symbol (Lisp_Object funsym, int abort_if_not_found) +{ + if (EQ (funsym, Qsymbol_value) + || EQ (funsym, Qdefault_value) + || EQ (funsym, Qsymbol_value_in_buffer) + || EQ (funsym, Qsymbol_value_in_console)) + return MAGIC_HANDLER_GET_VALUE; + + if (EQ (funsym, Qset) + || EQ (funsym, Qset_default)) + return MAGIC_HANDLER_SET_VALUE; + + if (EQ (funsym, Qboundp) + || EQ (funsym, Qglobally_boundp) + || EQ (funsym, Qdefault_boundp)) + return MAGIC_HANDLER_BOUND_PREDICATE; + + if (EQ (funsym, Qmakunbound)) + return MAGIC_HANDLER_MAKE_UNBOUND; + + if (EQ (funsym, Qlocal_variable_p)) + return MAGIC_HANDLER_LOCAL_PREDICATE; + + if (EQ (funsym, Qmake_variable_buffer_local) + || EQ (funsym, Qmake_local_variable)) + return MAGIC_HANDLER_MAKE_LOCAL; + + if (abort_if_not_found) + abort (); + signal_simple_error ("Unrecognized symbol-value function", funsym); + return MAGIC_HANDLER_MAX; +} + +static int +would_be_magic_handled (Lisp_Object sym, Lisp_Object funsym) +{ + /* does not take into account variable aliasing. */ + Lisp_Object valcontents = XSYMBOL (sym)->value; + enum lisp_magic_handler slot; + + if (!SYMBOL_VALUE_LISP_MAGIC_P (valcontents)) + return 0; + slot = handler_type_from_function_symbol (funsym, 1); + if (slot != MAGIC_HANDLER_SET_VALUE && slot != MAGIC_HANDLER_MAKE_UNBOUND + && slot != MAGIC_HANDLER_MAKE_LOCAL) + /* #### temporary kludge because we haven't implemented + lisp-magic variables completely */ + return 0; + return !NILP (XSYMBOL_VALUE_LISP_MAGIC (valcontents)->handler[slot]); +} + +static Lisp_Object +fetch_value_maybe_past_magic (Lisp_Object sym, + Lisp_Object follow_past_lisp_magic) +{ + Lisp_Object value = XSYMBOL (sym)->value; + if (SYMBOL_VALUE_LISP_MAGIC_P (value) + && (EQ (follow_past_lisp_magic, Qt) + || (!NILP (follow_past_lisp_magic) + && !would_be_magic_handled (sym, follow_past_lisp_magic)))) + value = XSYMBOL_VALUE_LISP_MAGIC (value)->shadowed; + return value; +} + +static Lisp_Object * +value_slot_past_magic (Lisp_Object sym) +{ + Lisp_Object *store_pointer = &XSYMBOL (sym)->value; + + if (SYMBOL_VALUE_LISP_MAGIC_P (*store_pointer)) + store_pointer = &XSYMBOL_VALUE_LISP_MAGIC (sym)->shadowed; + return store_pointer; +} + +static Lisp_Object +maybe_call_magic_handler (Lisp_Object sym, Lisp_Object funsym, int nargs, ...) +{ + va_list vargs; + Lisp_Object args[20]; /* should be enough ... */ + int i; + enum lisp_magic_handler htype; + Lisp_Object legerdemain; + struct symbol_value_lisp_magic *bfwd; + + assert (nargs >= 0 && nargs < 20); + legerdemain = XSYMBOL (sym)->value; + assert (SYMBOL_VALUE_LISP_MAGIC_P (legerdemain)); + bfwd = XSYMBOL_VALUE_LISP_MAGIC (legerdemain); + + va_start (vargs, nargs); + for (i = 0; i < nargs; i++) + args[i] = va_arg (vargs, Lisp_Object); + va_end (vargs); + + htype = handler_type_from_function_symbol (funsym, 1); + if (NILP (bfwd->handler[htype])) + return Qunbound; + /* #### should be reusing the arglist, not always consing anew. + Repeated handler invocations should not cause repeated consing. + Doesn't matter for now, because this is just a quick implementation + for obsolescence support. */ + return call5 (bfwd->handler[htype], sym, Flist (nargs, args), funsym, + bfwd->harg[htype], Qnil); +} + +DEFUN ("dontusethis-set-symbol-value-handler", Fdontusethis_set_symbol_value_handler, + 3, 5, 0, /* +Don't you dare use this. +If you do, suffer the wrath of Ben, who is likely to rename +this function (or change the semantics of its arguments) without +pity, thereby invalidating your code. +*/ + (variable, handler_type, handler, harg, keep_existing)) +{ + Lisp_Object valcontents; + struct symbol_value_lisp_magic *bfwd; + enum lisp_magic_handler htype; + int i; + + /* #### WARNING, only some handler types are implemented. See above. + Actions of other types will ignore a handler if it's there. + + #### Also, `chain-to-symbol-value-handler' and + `symbol-function-corresponding-function' are not implemented. */ + CHECK_SYMBOL (variable); + CHECK_SYMBOL (handler_type); + htype = decode_magic_handler_type (handler_type); + valcontents = XSYMBOL (variable)->value; + if (!SYMBOL_VALUE_LISP_MAGIC_P (valcontents)) + { + bfwd = alloc_lcrecord_type (struct symbol_value_lisp_magic, + &lrecord_symbol_value_lisp_magic); + bfwd->magic.type = SYMVAL_LISP_MAGIC; + for (i = 0; i < MAGIC_HANDLER_MAX; i++) + { + bfwd->handler[i] = Qnil; + bfwd->harg[i] = Qnil; + } + bfwd->shadowed = valcontents; + XSETSYMBOL_VALUE_MAGIC (XSYMBOL (variable)->value, bfwd); + } + else + bfwd = XSYMBOL_VALUE_LISP_MAGIC (valcontents); + bfwd->handler[htype] = handler; + bfwd->harg[htype] = harg; + + for (i = 0; i < MAGIC_HANDLER_MAX; i++) + if (!NILP (bfwd->handler[i])) + break; + + if (i == MAGIC_HANDLER_MAX) + /* there are no remaining handlers, so remove the structure. */ + XSYMBOL (variable)->value = bfwd->shadowed; + + return Qnil; +} + + +/* functions for working with variable aliases. */ + +/* Follow the chain of variable aliases for SYMBOL. Return the + resulting symbol, whose value cell is guaranteed not to be a + symbol-value-varalias. + + Also maybe follow past symbol-value-lisp-magic -> symbol-value-varalias. + If FUNSYM is t, always follow in such a case. If FUNSYM is nil, + never follow; stop right there. Otherwise FUNSYM should be a + recognized symbol-value function symbol; this means, follow + unless there is a special handler for the named function. + + OK, there is at least one reason why it's necessary for + FOLLOW-PAST-LISP-MAGIC to be specified correctly: So that we + can always be sure to catch cyclic variable aliasing. If we never + follow past Lisp magic, then if the following is done: + + (defvaralias 'a 'b) + add some magic behavior to a, but not a "get-value" handler + (defvaralias 'b 'a) + + then an attempt to retrieve a's or b's value would cause infinite + looping in `symbol-value'. + + We (of course) can't always follow past Lisp magic, because then + we make any variable that is lisp-magic -> varalias behave as if + the lisp-magic is not present at all. + */ + +static Lisp_Object +follow_varalias_pointers (Lisp_Object symbol, + Lisp_Object follow_past_lisp_magic) +{ +#define VARALIAS_INDIRECTION_SUSPICION_LENGTH 16 + Lisp_Object tortoise, hare, val; + int count; + + /* quick out just in case */ + if (!SYMBOL_VALUE_MAGIC_P (XSYMBOL (symbol)->value)) + return symbol; + + /* Compare implementation of indirect_function(). */ + for (hare = tortoise = symbol, count = 0; + val = fetch_value_maybe_past_magic (hare, follow_past_lisp_magic), + SYMBOL_VALUE_VARALIAS_P (val); + hare = symbol_value_varalias_aliasee (XSYMBOL_VALUE_VARALIAS (val)), + count++) + { + if (count < VARALIAS_INDIRECTION_SUSPICION_LENGTH) continue; + + if (count & 1) + tortoise = symbol_value_varalias_aliasee + (XSYMBOL_VALUE_VARALIAS (fetch_value_maybe_past_magic + (tortoise, follow_past_lisp_magic))); + if (EQ (hare, tortoise)) + return Fsignal (Qcyclic_variable_indirection, list1 (symbol)); + } + + return hare; +} + +DEFUN ("defvaralias", Fdefvaralias, 2, 2, 0, /* +Define a variable as an alias for another variable. +Thenceforth, any operations performed on VARIABLE will actually be +performed on ALIAS. Both VARIABLE and ALIAS should be symbols. +If ALIAS is nil, remove any aliases for VARIABLE. +ALIAS can itself be aliased, and the chain of variable aliases +will be followed appropriately. +If VARIABLE already has a value, this value will be shadowed +until the alias is removed, at which point it will be restored. +Currently VARIABLE cannot be a built-in variable, a variable that +has a buffer-local value in any buffer, or the symbols nil or t. +\(ALIAS, however, can be any type of variable.) +*/ + (variable, alias)) +{ + struct symbol_value_varalias *bfwd; + Lisp_Object valcontents; + + CHECK_SYMBOL (variable); + reject_constant_symbols (variable, Qunbound, 0, Qt); + + valcontents = XSYMBOL (variable)->value; + + if (NILP (alias)) + { + if (SYMBOL_VALUE_VARALIAS_P (valcontents)) + { + XSYMBOL (variable)->value = + symbol_value_varalias_shadowed + (XSYMBOL_VALUE_VARALIAS (valcontents)); + } + return Qnil; + } + + CHECK_SYMBOL (alias); + if (SYMBOL_VALUE_VARALIAS_P (valcontents)) + { + /* transmogrify */ + XSYMBOL_VALUE_VARALIAS (valcontents)->aliasee = alias; + return Qnil; + } + + if (SYMBOL_VALUE_MAGIC_P (valcontents) + && !UNBOUNDP (valcontents)) + signal_simple_error ("Variable is magic and cannot be aliased", variable); + reject_constant_symbols (variable, Qunbound, 0, Qt); + + bfwd = alloc_lcrecord_type (struct symbol_value_varalias, + &lrecord_symbol_value_varalias); + bfwd->magic.type = SYMVAL_VARALIAS; + bfwd->aliasee = alias; + bfwd->shadowed = valcontents; + + XSETSYMBOL_VALUE_MAGIC (valcontents, bfwd); + XSYMBOL (variable)->value = valcontents; + return Qnil; +} + +DEFUN ("variable-alias", Fvariable_alias, 1, 2, 0, /* +If VARIABLE is aliased to another variable, return that variable. +VARIABLE should be a symbol. If VARIABLE is not aliased, return nil. +Variable aliases are created with `defvaralias'. See also +`indirect-variable'. +*/ + (variable, follow_past_lisp_magic)) +{ + Lisp_Object valcontents; + + CHECK_SYMBOL (variable); + if (!NILP (follow_past_lisp_magic) && !EQ (follow_past_lisp_magic, Qt)) + { + CHECK_SYMBOL (follow_past_lisp_magic); + handler_type_from_function_symbol (follow_past_lisp_magic, 0); + } + + valcontents = fetch_value_maybe_past_magic (variable, + follow_past_lisp_magic); + + if (SYMBOL_VALUE_VARALIAS_P (valcontents)) + return symbol_value_varalias_aliasee + (XSYMBOL_VALUE_VARALIAS (valcontents)); + else + return Qnil; +} + +DEFUN ("indirect-variable", Findirect_variable, 1, 2, 0, /* +Return the variable at the end of OBJECT's variable-alias chain. +If OBJECT is a symbol, follow all variable aliases and return +the final (non-aliased) symbol. Variable aliases are created with +the function `defvaralias'. +If OBJECT is not a symbol, just return it. +Signal a cyclic-variable-indirection error if there is a loop in the +variable chain of symbols. +*/ + (object, follow_past_lisp_magic)) +{ + if (!SYMBOLP (object)) + return object; + if (!NILP (follow_past_lisp_magic) && !EQ (follow_past_lisp_magic, Qt)) + { + CHECK_SYMBOL (follow_past_lisp_magic); + handler_type_from_function_symbol (follow_past_lisp_magic, 0); + } + return follow_varalias_pointers (object, follow_past_lisp_magic); +} + + +/************************************************************************/ +/* initialization */ +/************************************************************************/ + +/* A dumped XEmacs image has a lot more than 1511 symbols. Last + estimate was that there were actually around 6300. So let's try + making this bigger and see if we get better hashing behavior. */ +#define OBARRAY_SIZE 16411 + +#ifndef Qzero +Lisp_Object Qzero; +#endif +#ifndef Qnull_pointer +Lisp_Object Qnull_pointer; +#endif + +/* some losing systems can't have static vars at function scope... */ +static struct symbol_value_magic guts_of_unbound_marker = + { { symbol_value_forward_lheader_initializer, 0, 69}, + SYMVAL_UNBOUND_MARKER }; + +void +init_symbols_once_early (void) +{ +#ifndef Qzero + Qzero = make_int (0); /* Only used if Lisp_Object is a union type */ +#endif + +#ifndef Qnull_pointer + /* C guarantees that Qnull_pointer will be initialized to all 0 bits, + so the following is actually a no-op. */ + XSETOBJ (Qnull_pointer, (enum Lisp_Type) 0, 0); +#endif + + /* Bootstrapping problem: Qnil isn't set when make_string_nocopy is + called the first time. */ + Qnil = Fmake_symbol (make_string_nocopy ((CONST Bufbyte *) "nil", 3)); + XSYMBOL (Qnil)->name->plist = Qnil; + XSYMBOL (Qnil)->value = Qnil; /* Nihil ex nihil */ + XSYMBOL (Qnil)->plist = Qnil; + + Vobarray = make_vector (OBARRAY_SIZE, Qzero); + initial_obarray = Vobarray; + staticpro (&initial_obarray); + /* Intern nil in the obarray */ + { + int hash = hash_string (string_data (XSYMBOL (Qnil)->name), 3); + XVECTOR_DATA (Vobarray)[hash % OBARRAY_SIZE] = Qnil; + } + + { + /* Required to get around a GCC syntax error on certain + architectures */ + struct symbol_value_magic *tem = &guts_of_unbound_marker; + + XSETSYMBOL_VALUE_MAGIC (Qunbound, tem); + } + if ((CONST void *) XPNTR (Qunbound) != + (CONST void *)&guts_of_unbound_marker) + { + /* This might happen on DATA_SEG_BITS machines. */ + /* abort (); */ + /* Can't represent a pointer to constant C data using a Lisp_Object. + So heap-allocate it. */ + struct symbol_value_magic *urk = xnew (struct symbol_value_magic); + memcpy (urk, &guts_of_unbound_marker, sizeof (*urk)); + XSETSYMBOL_VALUE_MAGIC (Qunbound, urk); + } + + XSYMBOL (Qnil)->function = Qunbound; + + defsymbol (&Qt, "t"); + XSYMBOL (Qt)->value = Qt; /* Veritas aetera */ + Vquit_flag = Qnil; + + pdump_wire (&Qnil); + pdump_wire (&Qunbound); + pdump_wire (&Vquit_flag); +} + +void +defsymbol_nodump (Lisp_Object *location, CONST char *name) +{ + *location = Fintern (make_string_nocopy ((CONST Bufbyte *) name, + strlen (name)), + Qnil); + staticpro_nodump (location); +} + +void +defsymbol (Lisp_Object *location, CONST char *name) +{ + *location = Fintern (make_string_nocopy ((CONST Bufbyte *) name, + strlen (name)), + Qnil); + staticpro (location); +} + +void +defkeyword (Lisp_Object *location, CONST char *name) +{ + defsymbol (location, name); + Fset (*location, *location); +} + +#ifdef DEBUG_XEMACS +/* Check that nobody spazzed writing a DEFUN. */ +static void +check_sane_subr (Lisp_Subr *subr, Lisp_Object sym) +{ + assert (subr->min_args >= 0); + assert (subr->min_args <= SUBR_MAX_ARGS); + + if (subr->max_args != MANY && + subr->max_args != UNEVALLED) + { + /* Need to fix lisp.h and eval.c if SUBR_MAX_ARGS too small */ + assert (subr->max_args <= SUBR_MAX_ARGS); + assert (subr->min_args <= subr->max_args); + } + + assert (UNBOUNDP (XSYMBOL (sym)->function)); +} +#else +#define check_sane_subr(subr, sym) /* nothing */ +#endif + +#ifdef HAVE_SHLIB +/* + * If we are not in a pure undumped Emacs, we need to make a duplicate of + * the subr. This is because the only time this function will be called + * in a running Emacs is when a dynamically loaded module is adding a + * subr, and we need to make sure that the subr is in allocated, Lisp- + * accessible memory. The address assigned to the static subr struct + * in the shared object will be a trampoline address, so we need to create + * a copy here to ensure that a real address is used. + * + * Once we have copied everything across, we re-use the original static + * structure to store a pointer to the newly allocated one. This will be + * used in emodules.c by emodules_doc_subr() to find a pointer to the + * allocated object so that we can set its doc string propperly. + * + * NOTE: We dont actually use the DOC pointer here any more, but we did + * in an earlier implementation of module support. There is no harm in + * setting it here in case we ever need it in future implementations. + * subr->doc will point to the new subr structure that was allocated. + * Code can then get this value from the statis subr structure and use + * it if required. + * + * FIXME: Should newsubr be staticpro()'ed? I dont think so but I need + * a guru to check. + */ +#define check_module_subr() \ +do { \ + if (initialized) { \ + struct Lisp_Subr *newsubr; \ + newsubr = (Lisp_Subr *)xmalloc(sizeof(struct Lisp_Subr)); \ + memcpy (newsubr, subr, sizeof(struct Lisp_Subr)); \ + subr->doc = (CONST char *)newsubr; \ + subr = newsubr; \ + } \ +} while (0) +#else /* ! HAVE_SHLIB */ +#define check_module_subr() +#endif + +void +defsubr (Lisp_Subr *subr) +{ + Lisp_Object sym = intern (subr_name (subr)); + Lisp_Object fun; + + check_sane_subr (subr, sym); + check_module_subr (); + + XSETSUBR (fun, subr); + XSYMBOL (sym)->function = fun; +} + +/* Define a lisp macro using a Lisp_Subr. */ +void +defsubr_macro (Lisp_Subr *subr) +{ + Lisp_Object sym = intern (subr_name (subr)); + Lisp_Object fun; + + check_sane_subr (subr, sym); + check_module_subr(); + + XSETSUBR (fun, subr); + XSYMBOL (sym)->function = Fcons (Qmacro, fun); +} + +void +deferror (Lisp_Object *symbol, CONST char *name, CONST char *messuhhj, + Lisp_Object inherits_from) +{ + Lisp_Object conds; + defsymbol (symbol, name); + + assert (SYMBOLP (inherits_from)); + conds = Fget (inherits_from, Qerror_conditions, Qnil); + Fput (*symbol, Qerror_conditions, Fcons (*symbol, conds)); + /* NOT build_translated_string (). This function is called at load time + and the string needs to get translated at run time. (This happens + in the function (display-error) in cmdloop.el.) */ + Fput (*symbol, Qerror_message, build_string (messuhhj)); +} + +void +syms_of_symbols (void) +{ + defsymbol (&Qvariable_documentation, "variable-documentation"); + defsymbol (&Qvariable_domain, "variable-domain"); /* I18N3 */ + defsymbol (&Qad_advice_info, "ad-advice-info"); + defsymbol (&Qad_activate, "ad-activate"); + + defsymbol (&Qget_value, "get-value"); + defsymbol (&Qset_value, "set-value"); + defsymbol (&Qbound_predicate, "bound-predicate"); + defsymbol (&Qmake_unbound, "make-unbound"); + defsymbol (&Qlocal_predicate, "local-predicate"); + defsymbol (&Qmake_local, "make-local"); + + defsymbol (&Qboundp, "boundp"); + defsymbol (&Qglobally_boundp, "globally-boundp"); + defsymbol (&Qmakunbound, "makunbound"); + defsymbol (&Qsymbol_value, "symbol-value"); + defsymbol (&Qset, "set"); + defsymbol (&Qsetq_default, "setq-default"); + defsymbol (&Qdefault_boundp, "default-boundp"); + defsymbol (&Qdefault_value, "default-value"); + defsymbol (&Qset_default, "set-default"); + defsymbol (&Qmake_variable_buffer_local, "make-variable-buffer-local"); + defsymbol (&Qmake_local_variable, "make-local-variable"); + defsymbol (&Qkill_local_variable, "kill-local-variable"); + defsymbol (&Qkill_console_local_variable, "kill-console-local-variable"); + defsymbol (&Qsymbol_value_in_buffer, "symbol-value-in-buffer"); + defsymbol (&Qsymbol_value_in_console, "symbol-value-in-console"); + defsymbol (&Qlocal_variable_p, "local-variable-p"); + + defsymbol (&Qconst_integer, "const-integer"); + defsymbol (&Qconst_boolean, "const-boolean"); + defsymbol (&Qconst_object, "const-object"); + defsymbol (&Qconst_specifier, "const-specifier"); + defsymbol (&Qdefault_buffer, "default-buffer"); + defsymbol (&Qcurrent_buffer, "current-buffer"); + defsymbol (&Qconst_current_buffer, "const-current-buffer"); + defsymbol (&Qdefault_console, "default-console"); + defsymbol (&Qselected_console, "selected-console"); + defsymbol (&Qconst_selected_console, "const-selected-console"); + + DEFSUBR (Fintern); + DEFSUBR (Fintern_soft); + DEFSUBR (Funintern); + DEFSUBR (Fmapatoms); + DEFSUBR (Fapropos_internal); + + DEFSUBR (Fsymbol_function); + DEFSUBR (Fsymbol_plist); + DEFSUBR (Fsymbol_name); + DEFSUBR (Fmakunbound); + DEFSUBR (Ffmakunbound); + DEFSUBR (Fboundp); + DEFSUBR (Fglobally_boundp); + DEFSUBR (Ffboundp); + DEFSUBR (Ffset); + DEFSUBR (Fdefine_function); + Ffset (intern ("defalias"), intern ("define-function")); + DEFSUBR (Fsetplist); + DEFSUBR (Fsymbol_value_in_buffer); + DEFSUBR (Fsymbol_value_in_console); + DEFSUBR (Fbuilt_in_variable_type); + DEFSUBR (Fsymbol_value); + DEFSUBR (Fset); + DEFSUBR (Fdefault_boundp); + DEFSUBR (Fdefault_value); + DEFSUBR (Fset_default); + DEFSUBR (Fsetq_default); + DEFSUBR (Fmake_variable_buffer_local); + DEFSUBR (Fmake_local_variable); + DEFSUBR (Fkill_local_variable); + DEFSUBR (Fkill_console_local_variable); + DEFSUBR (Flocal_variable_p); + DEFSUBR (Fdefvaralias); + DEFSUBR (Fvariable_alias); + DEFSUBR (Findirect_variable); + DEFSUBR (Fdontusethis_set_symbol_value_handler); +} + +/* Create and initialize a Lisp variable whose value is forwarded to C data */ +void +defvar_magic (CONST char *symbol_name, CONST struct symbol_value_forward *magic) +{ + Lisp_Object sym, kludge; + + /* Check that `magic' points somewhere we can represent as a Lisp pointer */ + XSETOBJ (kludge, Lisp_Type_Record, magic); + if ((void *)magic != (void*) XPNTR (kludge)) + { + /* This might happen on DATA_SEG_BITS machines. */ + /* abort (); */ + /* Copy it to somewhere which is representable. */ + struct symbol_value_forward *p = xnew (struct symbol_value_forward); + memcpy (p, magic, sizeof *magic); + magic = p; + } + +#if defined(HAVE_SHLIB) + /* + * As with defsubr(), this will only be called in a dumped Emacs when + * we are adding variables from a dynamically loaded module. That means + * we can't use purespace. Take that into account. + */ + if (initialized) + sym = Fintern (build_string (symbol_name), Qnil); + else +#endif + sym = Fintern (make_string_nocopy ((CONST Bufbyte *) symbol_name, + strlen (symbol_name)), Qnil); + + XSETOBJ (XSYMBOL (sym)->value, Lisp_Type_Record, magic); +} + +void +vars_of_symbols (void) +{ + DEFVAR_LISP ("obarray", &Vobarray /* +Symbol table for use by `intern' and `read'. +It is a vector whose length ought to be prime for best results. +The vector's contents don't make sense if examined from Lisp programs; +to find all the symbols in an obarray, use `mapatoms'. +*/ ); + /* obarray has been initialized long before */ +}