keymap.c

/* Manipulation of keymaps
   Copyright (C) 1985-1988, 1993-1995, 1998-2018 Free Software
   Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs 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 3 of the License, or (at
your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */

/* Old BUGS:
   - [M-C-a] != [?\M-\C-a]
   - [M-f2] != [?\e f2].
   - (define-key map [menu-bar foo] <bla>) does not always place <bla>
     at the head of the menu (if `foo' was already bound earlier and
     then unbound, for example).
   TODO:
   - allow many more Meta -> ESC mappings (like Hyper -> C-e for Emacspeak)
   - Think about the various defaulting that's currently hard-coded in
     keyboard.c (uppercase->lowercase, char->charset, button-events, ...)
     and make it more generic.  Maybe we should allow mappings of the
     form (PREDICATE . BINDING) as generalization of the default binding,
     tho probably a cleaner way to attack this is to allow functional
     keymaps (i.e. keymaps that are implemented as functions that implement
     a few different methods like `lookup', `map', ...).
   - Make [a] equivalent to [?a].
   BEWARE:
   - map-keymap should work meaningfully even if entries are added/removed
     to the keymap while iterating through it:
       start - removed <= visited <= start + added
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>

#include "lisp.h"
#include "commands.h"
#include "character.h"
#include "buffer.h"
#include "keyboard.h"
#include "termhooks.h"
#include "blockinput.h"
#include "puresize.h"
#include "intervals.h"
#include "keymap.h"
#include "window.h"

/* Actually allocate storage for these variables.  */

Lisp_Object current_global_map;	/* Current global keymap.  */

Lisp_Object global_map;		/* Default global key bindings.  */

Lisp_Object meta_map;		/* The keymap used for globally bound
				   ESC-prefixed default commands.  */

Lisp_Object control_x_map;	/* The keymap used for globally bound
				   C-x-prefixed default commands.  */

				/* The keymap used by the minibuf for local
				   bindings when spaces are allowed in the
				   minibuf.  */

				/* The keymap used by the minibuf for local
				   bindings when spaces are not encouraged
				   in the minibuf.  */

/* Alist of elements like (DEL . "\d").  */
static Lisp_Object exclude_keys;

/* Pre-allocated 2-element vector for Fcommand_remapping to use.  */
static Lisp_Object command_remapping_vector;

/* Hash table used to cache a reverse-map to speed up calls to where-is.  */
static Lisp_Object where_is_cache;
/* Which keymaps are reverse-stored in the cache.  */
static Lisp_Object where_is_cache_keymaps;

static Lisp_Object store_in_keymap (Lisp_Object, Lisp_Object, Lisp_Object);

static Lisp_Object define_as_prefix (Lisp_Object, Lisp_Object);
static void describe_command (Lisp_Object, Lisp_Object);
static void describe_translation (Lisp_Object, Lisp_Object);
static void describe_map (Lisp_Object, Lisp_Object,
                          void (*) (Lisp_Object, Lisp_Object),
			  bool, Lisp_Object, Lisp_Object *, bool, bool);
static void describe_vector (Lisp_Object, Lisp_Object, Lisp_Object,
                             void (*) (Lisp_Object, Lisp_Object), bool,
                             Lisp_Object, Lisp_Object, bool, bool);
static void silly_event_symbol_error (Lisp_Object);
static Lisp_Object get_keyelt (Lisp_Object, bool);

static void
CHECK_VECTOR_OR_CHAR_TABLE (Lisp_Object x)
{
  CHECK_TYPE (VECTORP (x) || CHAR_TABLE_P (x), Qvector_or_char_table_p, x);
}

/* Keymap object support - constructors and predicates.			*/

DEFUN ("make-keymap", Fmake_keymap, Smake_keymap, 0, 1, 0,
       doc: /* Construct and return a new keymap, of the form (keymap CHARTABLE . ALIST).
CHARTABLE is a char-table that holds the bindings for all characters
without modifiers.  All entries in it are initially nil, meaning
"command undefined".  ALIST is an assoc-list which holds bindings for
function keys, mouse events, and any other things that appear in the
input stream.  Initially, ALIST is nil.

The optional arg STRING supplies a menu name for the keymap
in case you use it as a menu with `x-popup-menu'.  */)
  (Lisp_Object string)
{
  Lisp_Object tail;
  if (!NILP (string))
    tail = list1 (string);
  else
    tail = Qnil;
  return Fcons (Qkeymap,
		Fcons (Fmake_char_table (Qkeymap, Qnil), tail));
}

DEFUN ("make-sparse-keymap", Fmake_sparse_keymap, Smake_sparse_keymap, 0, 1, 0,
       doc: /* Construct and return a new sparse keymap.
Its car is `keymap' and its cdr is an alist of (CHAR . DEFINITION),
which binds the character CHAR to DEFINITION, or (SYMBOL . DEFINITION),
which binds the function key or mouse event SYMBOL to DEFINITION.
Initially the alist is nil.

The optional arg STRING supplies a menu name for the keymap
in case you use it as a menu with `x-popup-menu'.  */)
  (Lisp_Object string)
{
  if (!NILP (string))
    {
      if (!NILP (Vpurify_flag))
	string = Fpurecopy (string);
      return list2 (Qkeymap, string);
    }
  return list1 (Qkeymap);
}

/* This function is used for installing the standard key bindings
   at initialization time.

   For example:

   initial_define_key (control_x_map, Ctl('X'), "exchange-point-and-mark");  */

void
initial_define_key (Lisp_Object keymap, int key, const char *defname)
{
  store_in_keymap (keymap, make_number (key), intern_c_string (defname));
}

void
initial_define_lispy_key (Lisp_Object keymap, const char *keyname, const char *defname)
{
  store_in_keymap (keymap, intern_c_string (keyname), intern_c_string (defname));
}

DEFUN ("keymapp", Fkeymapp, Skeymapp, 1, 1, 0,
       doc: /* Return t if OBJECT is a keymap.

A keymap is a list (keymap . ALIST),
or a symbol whose function definition is itself a keymap.
ALIST elements look like (CHAR . DEFN) or (SYMBOL . DEFN);
a vector of densely packed bindings for small character codes
is also allowed as an element.  */)
  (Lisp_Object object)
{
  return (KEYMAPP (object) ? Qt : Qnil);
}

DEFUN ("keymap-prompt", Fkeymap_prompt, Skeymap_prompt, 1, 1, 0,
       doc: /* Return the prompt-string of a keymap MAP.
If non-nil, the prompt is shown in the echo-area
when reading a key-sequence to be looked-up in this keymap.  */)
  (Lisp_Object map)
{
  map = get_keymap (map, 0, 0);
  while (CONSP (map))
    {
      Lisp_Object tem = XCAR (map);
      if (STRINGP (tem))
	return tem;
      else if (KEYMAPP (tem))
	{
	  tem = Fkeymap_prompt (tem);
	  if (!NILP (tem))
	    return tem;
	}
      map = XCDR (map);
    }
  return Qnil;
}

/* Check that OBJECT is a keymap (after dereferencing through any
   symbols).  If it is, return it.

   If AUTOLOAD and if OBJECT is a symbol whose function value
   is an autoload form, do the autoload and try again.
   If AUTOLOAD, callers must assume GC is possible.

   ERROR_IF_NOT_KEYMAP controls how we respond if OBJECT isn't a keymap.
   If ERROR_IF_NOT_KEYMAP, signal an error; otherwise,
   just return Qnil.

   Note that most of the time, we don't want to pursue autoloads.
   Functions like Faccessible_keymaps which scan entire keymap trees
   shouldn't load every autoloaded keymap.  I'm not sure about this,
   but it seems to me that only read_key_sequence, Flookup_key, and
   Fdefine_key should cause keymaps to be autoloaded.

   This function can GC when AUTOLOAD is true, because it calls
   Fautoload_do_load which can GC.  */

Lisp_Object
get_keymap (Lisp_Object object, bool error_if_not_keymap, bool autoload)
{
  Lisp_Object tem;

 autoload_retry:
  if (NILP (object))
    goto end;
  if (CONSP (object) && EQ (XCAR (object), Qkeymap))
    return object;

  tem = indirect_function (object);
  if (CONSP (tem))
    {
      if (EQ (XCAR (tem), Qkeymap))
	return tem;

      /* Should we do an autoload?  Autoload forms for keymaps have
	 Qkeymap as their fifth element.  */
      if ((autoload || !error_if_not_keymap) && EQ (XCAR (tem), Qautoload)
	  && SYMBOLP (object))
	{
	  Lisp_Object tail;

	  tail = Fnth (make_number (4), tem);
	  if (EQ (tail, Qkeymap))
	    {
	      if (autoload)
		{
		  Fautoload_do_load (tem, object, Qnil);
		  goto autoload_retry;
		}
	      else
	      	return object;
	    }
	}
    }

 end:
  if (error_if_not_keymap)
    wrong_type_argument (Qkeymapp, object);
  return Qnil;
}

/* Return the parent map of KEYMAP, or nil if it has none.
   We assume that KEYMAP is a valid keymap.  */

static Lisp_Object
keymap_parent (Lisp_Object keymap, bool autoload)
{
  Lisp_Object list;

  keymap = get_keymap (keymap, 1, autoload);

  /* Skip past the initial element `keymap'.  */
  list = XCDR (keymap);
  for (; CONSP (list); list = XCDR (list))
    {
      /* See if there is another `keymap'.  */
      if (KEYMAPP (list))
	return list;
    }

  return get_keymap (list, 0, autoload);
}

DEFUN ("keymap-parent", Fkeymap_parent, Skeymap_parent, 1, 1, 0,
       doc: /* Return the parent keymap of KEYMAP.
If KEYMAP has no parent, return nil.  */)
  (Lisp_Object keymap)
{
  return keymap_parent (keymap, 1);
}

/* Check whether MAP is one of MAPS parents.  */
static bool
keymap_memberp (Lisp_Object map, Lisp_Object maps)
{
  if (NILP (map)) return 0;
  while (KEYMAPP (maps) && !EQ (map, maps))
    maps = keymap_parent (maps, 0);
  return (EQ (map, maps));
}

/* Set the parent keymap of MAP to PARENT.  */

DEFUN ("set-keymap-parent", Fset_keymap_parent, Sset_keymap_parent, 2, 2, 0,
       doc: /* Modify KEYMAP to set its parent map to PARENT.
Return PARENT.  PARENT should be nil or another keymap.  */)
  (Lisp_Object keymap, Lisp_Object parent)
{
  Lisp_Object list, prev;

  /* Flush any reverse-map cache.  */
  where_is_cache = Qnil; where_is_cache_keymaps = Qt;

  keymap = get_keymap (keymap, 1, 1);

  if (!NILP (parent))
    {
      parent = get_keymap (parent, 1, 0);

      /* Check for cycles.  */
      if (keymap_memberp (keymap, parent))
	error ("Cyclic keymap inheritance");
    }

  /* Skip past the initial element `keymap'.  */
  prev = keymap;
  while (1)
    {
      list = XCDR (prev);
      /* If there is a parent keymap here, replace it.
	 If we came to the end, add the parent in PREV.  */
      if (!CONSP (list) || KEYMAPP (list))
	{
	  CHECK_IMPURE (prev, XCONS (prev));
	  XSETCDR (prev, parent);
	  return parent;
	}
      prev = list;
    }
}


/* Look up IDX in MAP.  IDX may be any sort of event.
   Note that this does only one level of lookup; IDX must be a single
   event, not a sequence.

   MAP must be a keymap or a list of keymaps.

   If T_OK, bindings for Qt are treated as default
   bindings; any key left unmentioned by other tables and bindings is
   given the binding of Qt.

   If not T_OK, bindings for Qt are not treated specially.

   If NOINHERIT, don't accept a subkeymap found in an inherited keymap.

   Return Qunbound if no binding was found (and return Qnil if a nil
   binding was found).  */

static Lisp_Object
access_keymap_1 (Lisp_Object map, Lisp_Object idx,
		 bool t_ok, bool noinherit, bool autoload)
{
  /* If idx is a list (some sort of mouse click, perhaps?),
     the index we want to use is the car of the list, which
     ought to be a symbol.  */
  idx = EVENT_HEAD (idx);

  /* If idx is a symbol, it might have modifiers, which need to
     be put in the canonical order.  */
  if (SYMBOLP (idx))
    idx = reorder_modifiers (idx);
  else if (INTEGERP (idx))
    /* Clobber the high bits that can be present on a machine
       with more than 24 bits of integer.  */
    XSETFASTINT (idx, XINT (idx) & (CHAR_META | (CHAR_META - 1)));

  /* Handle the special meta -> esc mapping.  */
  if (INTEGERP (idx) && XFASTINT (idx) & meta_modifier)
    {
      /* See if there is a meta-map.  If there's none, there is
         no binding for IDX, unless a default binding exists in MAP.  */
      Lisp_Object event_meta_binding, event_meta_map;
      /* A strange value in which Meta is set would cause
	 infinite recursion.  Protect against that.  */
      if (XINT (meta_prefix_char) & CHAR_META)
	meta_prefix_char = make_number (27);
      event_meta_binding = access_keymap_1 (map, meta_prefix_char, t_ok,
					    noinherit, autoload);
      event_meta_map = get_keymap (event_meta_binding, 0, autoload);
      if (CONSP (event_meta_map))
	{
	  map = event_meta_map;
	  idx = make_number (XFASTINT (idx) & ~meta_modifier);
	}
      else if (t_ok)
	/* Set IDX to t, so that we only find a default binding.  */
	idx = Qt;
      else
	/* An explicit nil binding, or no binding at all.  */
	return NILP (event_meta_binding) ? Qnil : Qunbound;
    }

  /* t_binding is where we put a default binding that applies,
     to use in case we do not find a binding specifically
     for this key sequence.  */
  {
    Lisp_Object tail;
    Lisp_Object t_binding = Qunbound;
    Lisp_Object retval = Qunbound;
    Lisp_Object retval_tail = Qnil;

    for (tail = (CONSP (map) && EQ (Qkeymap, XCAR (map))) ? XCDR (map) : map;
	 (CONSP (tail)
	  || (tail = get_keymap (tail, 0, autoload), CONSP (tail)));
	 tail = XCDR (tail))
      {
	/* Qunbound in VAL means we have found no binding.  */
	Lisp_Object val = Qunbound;
	Lisp_Object binding = XCAR (tail);
	Lisp_Object submap = get_keymap (binding, 0, autoload);

	if (EQ (binding, Qkeymap))
	  {
	    if (noinherit || NILP (retval))
	      /* If NOINHERIT, stop here, the rest is inherited.  */
	      break;
	    else if (!EQ (retval, Qunbound))
	      {
		Lisp_Object parent_entry;
		eassert (KEYMAPP (retval));
		parent_entry
		  = get_keymap (access_keymap_1 (tail, idx,
						 t_ok, 0, autoload),
				0, autoload);
		if (KEYMAPP (parent_entry))
		  {
		    if (CONSP (retval_tail))
		      XSETCDR (retval_tail, parent_entry);
		    else
		      {
			retval_tail = Fcons (retval, parent_entry);
			retval = Fcons (Qkeymap, retval_tail);
		      }
		  }
		break;
	      }
	  }
	else if (CONSP (submap))
	  {
	    val = access_keymap_1 (submap, idx, t_ok, noinherit, autoload);
	  }
	else if (CONSP (binding))
	  {
	    Lisp_Object key = XCAR (binding);

	    if (EQ (key, idx))
	      val = XCDR (binding);
	    else if (t_ok && EQ (key, Qt))
	      {
		t_binding = XCDR (binding);
		t_ok = 0;
	      }
	  }
	else if (VECTORP (binding))
	  {
	    if (INTEGERP (idx) && XFASTINT (idx) < ASIZE (binding))
	      val = AREF (binding, XFASTINT (idx));
	  }
	else if (CHAR_TABLE_P (binding))
	  {
	    /* Character codes with modifiers
	       are not included in a char-table.
	       All character codes without modifiers are included.  */
	    if (INTEGERP (idx) && (XFASTINT (idx) & CHAR_MODIFIER_MASK) == 0)
	      {
		val = Faref (binding, idx);
		/* nil has a special meaning for char-tables, so
		   we use something else to record an explicitly
		   unbound entry.  */
		if (NILP (val))
		  val = Qunbound;
	      }
	  }

	/* If we found a binding, clean it up and return it.  */
	if (!EQ (val, Qunbound))
	  {
	    if (EQ (val, Qt))
	      /* A Qt binding is just like an explicit nil binding
		 (i.e. it shadows any parent binding but not bindings in
		 keymaps of lower precedence).  */
	      val = Qnil;

	    val = get_keyelt (val, autoload);

	    if (!KEYMAPP (val))
	      {
		if (NILP (retval) || EQ (retval, Qunbound))
		  retval = val;
		if (!NILP (val))
		  break;  /* Shadows everything that follows.  */
	      }
	    else if (NILP (retval) || EQ (retval, Qunbound))
	      retval = val;
	    else if (CONSP (retval_tail))
	      {
		XSETCDR (retval_tail, list1 (val));
		retval_tail = XCDR (retval_tail);
	      }
	    else
	      {
		retval_tail = list1 (val);
		retval = Fcons (Qkeymap, Fcons (retval, retval_tail));
	      }
	  }
	maybe_quit ();
      }

    return EQ (Qunbound, retval) ? get_keyelt (t_binding, autoload) : retval;
  }
}

Lisp_Object
access_keymap (Lisp_Object map, Lisp_Object idx,
	       bool t_ok, bool noinherit, bool autoload)
{
  Lisp_Object val = access_keymap_1 (map, idx, t_ok, noinherit, autoload);
  return EQ (val, Qunbound) ? Qnil : val;
}

static void
map_keymap_item (map_keymap_function_t fun, Lisp_Object args, Lisp_Object key, Lisp_Object val, void *data)
{
  if (EQ (val, Qt))
    val = Qnil;
  (*fun) (key, val, args, data);
}

union map_keymap
{
  struct
  {
    map_keymap_function_t fun;
    Lisp_Object args;
    void *data;
  } s;
  GCALIGNED_UNION
};
verify (alignof (union map_keymap) % GCALIGNMENT == 0);

static void
map_keymap_char_table_item (Lisp_Object args, Lisp_Object key, Lisp_Object val)
{
  if (!NILP (val))
    {
      /* If the key is a range, make a copy since map_char_table modifies
	 it in place.  */
      if (CONSP (key))
	key = Fcons (XCAR (key), XCDR (key));
      union map_keymap *md = XINTPTR (args);
      map_keymap_item (md->s.fun, md->s.args, key, val, md->s.data);
    }
}

/* Call FUN for every binding in MAP and stop at (and return) the parent.
   FUN is called with 4 arguments: FUN (KEY, BINDING, ARGS, DATA).  */
static Lisp_Object
map_keymap_internal (Lisp_Object map,
		     map_keymap_function_t fun,
		     Lisp_Object args,
		     void *data)
{
  Lisp_Object tail
    = (CONSP (map) && EQ (Qkeymap, XCAR (map))) ? XCDR (map) : map;

  for (; CONSP (tail) && !EQ (Qkeymap, XCAR (tail)); tail = XCDR (tail))
    {
      Lisp_Object binding = XCAR (tail);

      if (KEYMAPP (binding))	/* An embedded parent.  */
	break;
      else if (CONSP (binding))
	map_keymap_item (fun, args, XCAR (binding), XCDR (binding), data);
      else if (VECTORP (binding))
	{
	  /* Loop over the char values represented in the vector.  */
	  int len = ASIZE (binding);
	  int c;
	  for (c = 0; c < len; c++)
	    {
	      Lisp_Object character;
	      XSETFASTINT (character, c);
	      map_keymap_item (fun, args, character, AREF (binding, c), data);
	    }
	}
      else if (CHAR_TABLE_P (binding))
	{
	  union map_keymap mapdata = {{fun, args, data}};
	  map_char_table (map_keymap_char_table_item, Qnil, binding,
			  make_pointer_integer (&mapdata));
	}
    }

  return tail;
}

static void
map_keymap_call (Lisp_Object key, Lisp_Object val, Lisp_Object fun, void *dummy)
{
  call2 (fun, key, val);
}

/* Same as map_keymap_internal, but traverses parent keymaps as well.
   AUTOLOAD indicates that autoloaded keymaps should be loaded.  */
void
map_keymap (Lisp_Object map, map_keymap_function_t fun, Lisp_Object args,
	    void *data, bool autoload)
{
  map = get_keymap (map, 1, autoload);
  while (CONSP (map))
    {
      if (KEYMAPP (XCAR (map)))
	{
	  map_keymap (XCAR (map), fun, args, data, autoload);
	  map = XCDR (map);
	}
      else
	map = map_keymap_internal (map, fun, args, data);
      if (!CONSP (map))
	map = get_keymap (map, 0, autoload);
    }
}

/* Same as map_keymap, but does it right, properly eliminating duplicate
   bindings due to inheritance.   */
void
map_keymap_canonical (Lisp_Object map, map_keymap_function_t fun, Lisp_Object args, void *data)
{
  /* map_keymap_canonical may be used from redisplay (e.g. when building menus)
     so be careful to ignore errors and to inhibit redisplay.  */
  map = safe_call1 (Qkeymap_canonicalize, map);
  /* No need to use `map_keymap' here because canonical map has no parent.  */
  map_keymap_internal (map, fun, args, data);
}

DEFUN ("map-keymap-internal", Fmap_keymap_internal, Smap_keymap_internal, 2, 2, 0,
       doc: /* Call FUNCTION once for each event binding in KEYMAP.
FUNCTION is called with two arguments: the event that is bound, and
the definition it is bound to.  The event may be a character range.
If KEYMAP has a parent, this function returns it without processing it.  */)
  (Lisp_Object function, Lisp_Object keymap)
{
  keymap = get_keymap (keymap, 1, 1);
  keymap = map_keymap_internal (keymap, map_keymap_call, function, NULL);
  return keymap;
}

DEFUN ("map-keymap", Fmap_keymap, Smap_keymap, 2, 3, 0,
       doc: /* Call FUNCTION once for each event binding in KEYMAP.
FUNCTION is called with two arguments: the event that is bound, and
the definition it is bound to.  The event may be a character range.

If KEYMAP has a parent, the parent's bindings are included as well.
This works recursively: if the parent has itself a parent, then the
grandparent's bindings are also included and so on.
usage: (map-keymap FUNCTION KEYMAP)  */)
  (Lisp_Object function, Lisp_Object keymap, Lisp_Object sort_first)
{
  if (! NILP (sort_first))
    return call2 (intern ("map-keymap-sorted"), function, keymap);

  map_keymap (keymap, map_keymap_call, function, NULL, 1);
  return Qnil;
}

/* Given OBJECT which was found in a slot in a keymap,
   trace indirect definitions to get the actual definition of that slot.
   An indirect definition is a list of the form
   (KEYMAP . INDEX), where KEYMAP is a keymap or a symbol defined as one
   and INDEX is the object to look up in KEYMAP to yield the definition.

   Also if OBJECT has a menu string as the first element,
   remove that.  Also remove a menu help string as second element.

   If AUTOLOAD, load autoloadable keymaps
   that are referred to with indirection.

   This can GC because menu_item_eval_property calls Feval.  */

static Lisp_Object
get_keyelt (Lisp_Object object, bool autoload)
{
  while (1)
    {
      if (!(CONSP (object)))
	/* This is really the value.  */
	return object;

      /* If the keymap contents looks like (menu-item name . DEFN)
	 or (menu-item name DEFN ...) then use DEFN.
	 This is a new format menu item.  */
      else if (EQ (XCAR (object), Qmenu_item))
	{
	  if (CONSP (XCDR (object)))
	    {
	      Lisp_Object tem;

	      object = XCDR (XCDR (object));
	      tem = object;
	      if (CONSP (object))
		object = XCAR (object);

	      /* If there's a `:filter FILTER', apply FILTER to the
		 menu-item's definition to get the real definition to
		 use.  */
	      for (; CONSP (tem) && CONSP (XCDR (tem)); tem = XCDR (tem))
		if (EQ (XCAR (tem), QCfilter) && autoload)
		  {
		    Lisp_Object filter;
		    filter = XCAR (XCDR (tem));
		    filter = list2 (filter, list2 (Qquote, object));
		    object = menu_item_eval_property (filter);
		    break;
		  }
	    }
	  else
	    /* Invalid keymap.  */
	    return object;
	}

      /* If the keymap contents looks like (STRING . DEFN), use DEFN.
	 Keymap alist elements like (CHAR MENUSTRING . DEFN)
	 will be used by HierarKey menus.  */
      else if (STRINGP (XCAR (object)))
	object = XCDR (object);

      else
	return object;
    }
}

static Lisp_Object
store_in_keymap (Lisp_Object keymap, register Lisp_Object idx, Lisp_Object def)
{
  /* Flush any reverse-map cache.  */
  where_is_cache = Qnil;
  where_is_cache_keymaps = Qt;

  if (EQ (idx, Qkeymap))
    error ("`keymap' is reserved for embedded parent maps");

  /* If we are preparing to dump, and DEF is a menu element
     with a menu item indicator, copy it to ensure it is not pure.  */
  if (CONSP (def) && PURE_P (XCONS (def))
      && (EQ (XCAR (def), Qmenu_item) || STRINGP (XCAR (def))))
    def = Fcons (XCAR (def), XCDR (def));

  if (!CONSP (keymap) || !EQ (XCAR (keymap), Qkeymap))
    error ("attempt to define a key in a non-keymap");

  /* If idx is a cons, and the car part is a character, idx must be of
     the form (FROM-CHAR . TO-CHAR).  */
  if (CONSP (idx) && CHARACTERP (XCAR (idx)))
    CHECK_CHARACTER_CDR (idx);
  else
    /* If idx is a list (some sort of mouse click, perhaps?),
       the index we want to use is the car of the list, which
       ought to be a symbol.  */
    idx = EVENT_HEAD (idx);

  /* If idx is a symbol, it might have modifiers, which need to
     be put in the canonical order.  */
  if (SYMBOLP (idx))
    idx = reorder_modifiers (idx);
  else if (INTEGERP (idx))
    /* Clobber the high bits that can be present on a machine
       with more than 24 bits of integer.  */
    XSETFASTINT (idx, XINT (idx) & (CHAR_META | (CHAR_META - 1)));

  /* Scan the keymap for a binding of idx.  */
  {
    Lisp_Object tail;

    /* The cons after which we should insert new bindings.  If the
       keymap has a table element, we record its position here, so new
       bindings will go after it; this way, the table will stay
       towards the front of the alist and character lookups in dense
       keymaps will remain fast.  Otherwise, this just points at the
       front of the keymap.  */
    Lisp_Object insertion_point;

    insertion_point = keymap;
    for (tail = XCDR (keymap); CONSP (tail); tail = XCDR (tail))
      {
	Lisp_Object elt;

	elt = XCAR (tail);
	if (VECTORP (elt))
	  {
	    if (NATNUMP (idx) && XFASTINT (idx) < ASIZE (elt))
	      {
		CHECK_IMPURE (elt, XVECTOR (elt));
		ASET (elt, XFASTINT (idx), def);
		return def;
	      }
	    else if (CONSP (idx) && CHARACTERP (XCAR (idx)))
	      {
		int from = XFASTINT (XCAR (idx));
		int to = XFASTINT (XCDR (idx));

		if (to >= ASIZE (elt))
		  to = ASIZE (elt) - 1;
		for (; from <= to; from++)
		  ASET (elt, from, def);
		if (to == XFASTINT (XCDR (idx)))
		  /* We have defined all keys in IDX.  */
		  return def;
	      }
	    insertion_point = tail;
	  }
	else if (CHAR_TABLE_P (elt))
	  {
	    /* Character codes with modifiers
	       are not included in a char-table.
	       All character codes without modifiers are included.  */
	    if (NATNUMP (idx) && !(XFASTINT (idx) & CHAR_MODIFIER_MASK))
	      {
		Faset (elt, idx,
		       /* nil has a special meaning for char-tables, so
			  we use something else to record an explicitly
			  unbound entry.  */
		       NILP (def) ? Qt : def);
		return def;
	      }
	    else if (CONSP (idx) && CHARACTERP (XCAR (idx)))
	      {
		Fset_char_table_range (elt, idx, NILP (def) ? Qt : def);
		return def;
	      }
	    insertion_point = tail;
	  }
	else if (CONSP (elt))
	  {
	    if (EQ (Qkeymap, XCAR (elt)))
	      { /* A sub keymap.  This might be due to a lookup that found
		   two matching bindings (maybe because of a sub keymap).
		   It almost never happens (since the second binding normally
		   only happens in the inherited part of the keymap), but
		   if it does, we want to update the sub-keymap since the
		   main one might be temporary (built by access_keymap).  */
		tail = insertion_point = elt;
	      }
	    else if (EQ (idx, XCAR (elt)))
	      {
		CHECK_IMPURE (elt, XCONS (elt));
		XSETCDR (elt, def);
		return def;
	      }
	    else if (CONSP (idx)
		     && CHARACTERP (XCAR (idx))
		     && CHARACTERP (XCAR (elt)))