keymap.c

/* Manipulation of keymaps
   Copyright (C) 1985, 86,87,88,93,94,95,98,99, 2000, 2001
   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 2, 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; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */


#include <config.h>
#include <stdio.h>
#include "lisp.h"
#include "commands.h"
#include "buffer.h"
#include "charset.h"
#include "keyboard.h"
#include "termhooks.h"
#include "blockinput.h"
#include "puresize.h"
#include "intervals.h"
#include "keymap.h"

/* The number of elements in keymap vectors.  */
#define DENSE_TABLE_SIZE (0200)

/* 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 */

/* was MinibufLocalMap */
Lisp_Object Vminibuffer_local_map;
				/* The keymap used by the minibuf for local
				   bindings when spaces are allowed in the
				   minibuf */

/* was MinibufLocalNSMap */
Lisp_Object Vminibuffer_local_ns_map;
				/* The keymap used by the minibuf for local
				   bindings when spaces are not encouraged
				   in the minibuf */

/* keymap used for minibuffers when doing completion */
/* was MinibufLocalCompletionMap */
Lisp_Object Vminibuffer_local_completion_map;

/* keymap used for minibuffers when doing completion and require a match */
/* was MinibufLocalMustMatchMap */
Lisp_Object Vminibuffer_local_must_match_map;

/* Alist of minor mode variables and keymaps.  */
Lisp_Object Vminor_mode_map_alist;

/* Alist of major-mode-specific overrides for
   minor mode variables and keymaps.  */
Lisp_Object Vminor_mode_overriding_map_alist;

/* Keymap mapping ASCII function key sequences onto their preferred forms.
   Initialized by the terminal-specific lisp files.  See DEFVAR for more
   documentation.  */
Lisp_Object Vfunction_key_map;

/* Keymap mapping ASCII function key sequences onto their preferred forms.  */
Lisp_Object Vkey_translation_map;

/* A list of all commands given new bindings since a certain time
   when nil was stored here.
   This is used to speed up recomputation of menu key equivalents
   when Emacs starts up.   t means don't record anything here.  */
Lisp_Object Vdefine_key_rebound_commands;

Lisp_Object Qkeymapp, Qkeymap, Qnon_ascii, Qmenu_item, Qremap;

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

/* Pre-allocated 2-element vector for Fremap_command to use.  */
static Lisp_Object remap_command_vector;

/* A char with the CHAR_META bit set in a vector or the 0200 bit set
   in a string key sequence is equivalent to prefixing with this
   character.  */
extern Lisp_Object meta_prefix_char;

extern Lisp_Object Voverriding_local_map;

/* 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 P_ ((Lisp_Object, Lisp_Object, Lisp_Object));
static void fix_submap_inheritance P_ ((Lisp_Object, Lisp_Object, Lisp_Object));

static Lisp_Object define_as_prefix P_ ((Lisp_Object, Lisp_Object));
static void describe_command P_ ((Lisp_Object, Lisp_Object));
static void describe_translation P_ ((Lisp_Object, Lisp_Object));
static void describe_map P_ ((Lisp_Object, Lisp_Object,
			      void (*) P_ ((Lisp_Object, Lisp_Object)),
			      int, Lisp_Object, Lisp_Object*, int));
static void silly_event_symbol_error P_ ((Lisp_Object));

/* 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 the ASCII
characters.  ALIST is an assoc-list which holds bindings for function keys,
mouse events, and any other things that appear in the input stream.
All entries in it are initially nil, meaning "command undefined".

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

/* 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 (keymap, key, defname)
     Lisp_Object keymap;
     int key;
     char *defname;
{
  store_in_keymap (keymap, make_number (key), intern (defname));
}

void
initial_define_lispy_key (keymap, keyname, defname)
     Lisp_Object keymap;
     char *keyname;
     char *defname;
{
  store_in_keymap (keymap, intern (keyname), intern (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.  */)
     (object)
     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.  */)
     (map)
     Lisp_Object map;
{
  while (CONSP (map))
    {
      register Lisp_Object tem;
      tem = Fcar (map);
      if (STRINGP (tem))
	return tem;
      map = Fcdr (map);
    }
  return Qnil;
}

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

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

   If the map needs to be autoloaded, but AUTOLOAD is zero (and ERROR
   is zero as well), return Qt.

   ERROR controls how we respond if OBJECT isn't a keymap.
   If ERROR is non-zero, 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 non-zero, because it calls
   do_autoload which can GC.  */

Lisp_Object
get_keymap (object, error, autoload)
     Lisp_Object object;
     int error, 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) && EQ (XCAR (tem), Qautoload))
	{
	  Lisp_Object tail;

	  tail = Fnth (make_number (4), tem);
	  if (EQ (tail, Qkeymap))
	    {
	      if (autoload)
		{
		  struct gcpro gcpro1, gcpro2;
		  
		  GCPRO2 (tem, object);
		  do_autoload (tem, object);
		  UNGCPRO;
		  
		  goto autoload_retry;
		}
	      else
	      	return Qt;
	    }
	}
    }

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

DEFUN ("keymap-parent", Fkeymap_parent, Skeymap_parent, 1, 1, 0,
       doc: /* Return the parent keymap of KEYMAP.  */)
     (keymap)
     Lisp_Object keymap;
{
  Lisp_Object list;

  keymap = get_keymap (keymap, 1, 1);

  /* 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, 1);
}


/* Check whether MAP is one of MAPS parents.  */
int
keymap_memberp (map, maps)
     Lisp_Object map, maps;
{
  if (NILP (map)) return 0;
  while (KEYMAPP (maps) && !EQ (map, maps))
    maps = Fkeymap_parent (maps);
  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.
PARENT should be nil or another keymap.  */)
     (keymap, parent)
     Lisp_Object keymap, parent;
{
  Lisp_Object list, prev;
  struct gcpro gcpro1;
  int i;

  /* Force a keymap flush for the next call to where-is.
     Since this can be called from within where-is, we don't set where_is_cache
     directly but only where_is_cache_keymaps, since where_is_cache shouldn't
     be changed during where-is, while where_is_cache_keymaps is only used at
     the very beginning of where-is and can thus be changed here without any
     adverse effect.
     This is a very minor correctness (rather than safety) issue.  */
  where_is_cache_keymaps = Qt;

  keymap = get_keymap (keymap, 1, 1);
  GCPRO1 (keymap);
  
  if (!NILP (parent))
    {
      parent = get_keymap (parent, 1, 1);

      /* 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))
	{
	  /* If we already have the right parent, return now
	     so that we avoid the loops below.  */
	  if (EQ (XCDR (prev), parent))
	    RETURN_UNGCPRO (parent);

	  XSETCDR (prev, parent);
	  break;
	}
      prev = list;
    }

  /* Scan through for submaps, and set their parents too.  */

  for (list = XCDR (keymap); CONSP (list); list = XCDR (list))
    {
      /* Stop the scan when we come to the parent.  */
      if (EQ (XCAR (list), Qkeymap))
	break;

      /* If this element holds a prefix map, deal with it.  */
      if (CONSP (XCAR (list))
	  && CONSP (XCDR (XCAR (list))))
	fix_submap_inheritance (keymap, XCAR (XCAR (list)),
				XCDR (XCAR (list)));

      if (VECTORP (XCAR (list)))
	for (i = 0; i < XVECTOR (XCAR (list))->size; i++)
	  if (CONSP (XVECTOR (XCAR (list))->contents[i]))
	    fix_submap_inheritance (keymap, make_number (i),
				    XVECTOR (XCAR (list))->contents[i]);

      if (CHAR_TABLE_P (XCAR (list)))
	{
	  Lisp_Object indices[3];

	  map_char_table (fix_submap_inheritance, Qnil, XCAR (list),
			  keymap, 0, indices);
	}
    }

  RETURN_UNGCPRO (parent);
}

/* EVENT is defined in MAP as a prefix, and SUBMAP is its definition.
   if EVENT is also a prefix in MAP's parent,
   make sure that SUBMAP inherits that definition as its own parent.  */

static void
fix_submap_inheritance (map, event, submap)
     Lisp_Object map, event, submap;
{
  Lisp_Object map_parent, parent_entry;

  /* SUBMAP is a cons that we found as a key binding.
     Discard the other things found in a menu key binding.  */

  submap = get_keymap (get_keyelt (submap, 0), 0, 0);

  /* If it isn't a keymap now, there's no work to do.  */
  if (!CONSP (submap))
    return;

  map_parent = Fkeymap_parent (map);
  if (!NILP (map_parent))
    parent_entry =
      get_keymap (access_keymap (map_parent, event, 0, 0, 0), 0, 0);
  else
    parent_entry = Qnil;

  /* If MAP's parent has something other than a keymap,
     our own submap shadows it completely.  */
  if (!CONSP (parent_entry))
    return;

  if (! EQ (parent_entry, submap))
    {
      Lisp_Object submap_parent;
      submap_parent = submap;
      while (1)
	{
	  Lisp_Object tem;

	  tem = Fkeymap_parent (submap_parent);

	  if (KEYMAPP (tem))
	    {
	      if (keymap_memberp (tem, parent_entry))
		/* Fset_keymap_parent could create a cycle.  */
		return;
	      submap_parent = tem;
	    }
	  else
	    break;
	}
      Fset_keymap_parent (submap_parent, parent_entry);
    }
}

/* 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. 

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

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

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

Lisp_Object
access_keymap (map, idx, t_ok, noinherit, autoload)
     Lisp_Object map;
     Lisp_Object idx;
     int t_ok;
     int noinherit;
     int autoload;
{
  Lisp_Object val;

  /* Qunbound in VAL means we have found no binding yet.  */
  val = Qunbound;

  /* 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) && XUINT (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 meta_map =
	get_keymap (access_keymap (map, meta_prefix_char,
				   t_ok, noinherit, autoload),
		    0, autoload);
      if (CONSP (meta_map))
	{
	  map = meta_map;
	  idx = make_number (XUINT (idx) & ~meta_modifier);
	}
      else if (t_ok)
	/* Set IDX to t, so that we only find a default binding.  */
	idx = Qt;
      else
	/* We know there is no binding.  */
	return Qnil;
    }

  {
    Lisp_Object tail;

    /* 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 t_binding;
    t_binding = Qnil;

    /* If `t_ok' is 2, both `t' and generic-char bindings are accepted.
       If it is 1, only generic-char bindings are accepted.
       Otherwise, neither are.  */
    t_ok = t_ok ? 2 : 0;

    for (tail = XCDR (map);
	 (CONSP (tail)
	  || (tail = get_keymap (tail, 0, autoload), CONSP (tail)));
	 tail = XCDR (tail))
      {
	Lisp_Object binding;

	binding = XCAR (tail);
	if (SYMBOLP (binding))
	  {
	    /* If NOINHERIT, stop finding prefix definitions
	       after we pass a second occurrence of the `keymap' symbol.  */
	    if (noinherit && EQ (binding, Qkeymap))
	      return Qnil;
	  }
	else if (CONSP (binding))
	  {
	    Lisp_Object key = XCAR (binding);
	    
	    if (EQ (key, idx))
	      val = XCDR (binding);
	    else if (t_ok
		     && INTEGERP (idx)
		     && (XINT (idx) & CHAR_MODIFIER_MASK) == 0
		     && INTEGERP (key)
		     && (XINT (key) & CHAR_MODIFIER_MASK) == 0
		     && !SINGLE_BYTE_CHAR_P (XINT (idx))
		     && !SINGLE_BYTE_CHAR_P (XINT (key))
		     && CHAR_VALID_P (XINT (key), 1)
		     && !CHAR_VALID_P (XINT (key), 0)
		     && (CHAR_CHARSET (XINT (key))
			 == CHAR_CHARSET (XINT (idx))))
	      {
		/* KEY is the generic character of the charset of IDX.
		   Use KEY's binding if there isn't a binding for IDX
		   itself.  */
		t_binding = XCDR (binding);
		t_ok = 0;
	      }
	    else if (t_ok > 1 && EQ (key, Qt))
	      {
		t_binding = XCDR (binding);
		t_ok = 1;
	      }
	  }
	else if (VECTORP (binding))
	  {
	    if (NATNUMP (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 (NATNUMP (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))
	      fix_submap_inheritance (map, idx, val);
	    return val;
	  }
	QUIT;
      }

    return get_keyelt (t_binding, autoload);
  }
}

/* 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 is nonzero, load autoloadable keymaps
   that are referred to with indirection.  */

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

      /* If the keymap contents looks like (keymap ...) or (lambda ...)
	 then use itself. */
      else if (EQ (XCAR (object), Qkeymap) || EQ (XCAR (object), Qlambda))
	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);
	  /* Also remove a menu help string, if any,
	     following the menu item name.  */
	  if (CONSP (object) && STRINGP (XCAR (object)))
	    object = XCDR (object);
	  /* Also remove the sublist that caches key equivalences, if any.  */
	  if (CONSP (object) && CONSP (XCAR (object)))
	    {
	      Lisp_Object carcar;
	      carcar = XCAR (XCAR (object));
	      if (NILP (carcar) || VECTORP (carcar))
		object = XCDR (object);
	    }
	}

      /* If the contents are (KEYMAP . ELEMENT), go indirect.  */
      else
	{
	  Lisp_Object map;
	  map = get_keymap (Fcar_safe (object), 0, autoload);
	  return (!CONSP (map) ? object /* Invalid keymap */
		  : access_keymap (map, Fcdr (object), 0, 0, autoload));
	}
    }
}

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

  /* 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 (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 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))
	      {
		ASET (elt, XFASTINT (idx), def);
		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;
	      }
	    insertion_point = tail;
	  }
	else if (CONSP (elt))
	  {
	    if (EQ (idx, XCAR (elt)))
	      {
		XSETCDR (elt, def);
		return def;
	      }
	  }
	else if (EQ (elt, Qkeymap))
	  /* If we find a 'keymap' symbol in the spine of KEYMAP,
	     then we must have found the start of a second keymap
	     being used as the tail of KEYMAP, and a binding for IDX
	     should be inserted before it.  */
	  goto keymap_end;

	QUIT;
      }

  keymap_end:
    /* We have scanned the entire keymap, and not found a binding for
       IDX.  Let's add one.  */
    XSETCDR (insertion_point,
	     Fcons (Fcons (idx, def), XCDR (insertion_point)));
  }
  
  return def;
}

EXFUN (Fcopy_keymap, 1);

void
copy_keymap_1 (chartable, idx, elt)
     Lisp_Object chartable, idx, elt;
{
  if (CONSP (elt) && EQ (XCAR (elt), Qkeymap))
    Faset (chartable, idx, Fcopy_keymap (elt));
}

DEFUN ("copy-keymap", Fcopy_keymap, Scopy_keymap, 1, 1, 0,
       doc: /* Return a copy of the keymap KEYMAP.
The copy starts out with the same definitions of KEYMAP,
but changing either the copy or KEYMAP does not affect the other.
Any key definitions that are subkeymaps are recursively copied.
However, a key definition which is a symbol whose definition is a keymap
is not copied.  */)
     (keymap)
     Lisp_Object keymap;
{
  /* FIXME: This doesn't properly copy menu-items in vectors.  */
  /* FIXME: This also copies the parent keymap.  */

  register Lisp_Object copy, tail;

  copy = Fcopy_alist (get_keymap (keymap, 1, 0));

  for (tail = copy; CONSP (tail); tail = XCDR (tail))
    {
      Lisp_Object elt;

      elt = XCAR (tail);
      if (CHAR_TABLE_P (elt))
	{
	  Lisp_Object indices[3];

	  elt = Fcopy_sequence (elt);
	  XSETCAR (tail, elt);

	  map_char_table (copy_keymap_1, Qnil, elt, elt, 0, indices);
	}
      else if (VECTORP (elt))
	{
	  int i;

	  elt = Fcopy_sequence (elt);
	  XSETCAR (tail, elt);

	  for (i = 0; i < ASIZE (elt); i++)
	    if (CONSP (AREF (elt, i)) && EQ (XCAR (AREF (elt, i)), Qkeymap))
	      ASET (elt, i, Fcopy_keymap (AREF (elt, i)));
	}
      else if (CONSP (elt) && CONSP (XCDR (elt)))
	{
	  Lisp_Object tem;
	  tem = XCDR (elt);

	  /* Is this a new format menu item.  */
	  if (EQ (XCAR (tem),Qmenu_item))
	    {
	      /* Copy cell with menu-item marker.  */
	      XSETCDR (elt,
		       Fcons (XCAR (tem), XCDR (tem)));
	      elt = XCDR (elt);
	      tem = XCDR (elt);
	      if (CONSP (tem))
		{
		  /* Copy cell with menu-item name.  */
		  XSETCDR (elt,
			   Fcons (XCAR (tem), XCDR (tem)));
		  elt = XCDR (elt);
		  tem = XCDR (elt);
		};
	      if (CONSP (tem))
		{
		  /* Copy cell with binding and if the binding is a keymap,
		     copy that.  */
		  XSETCDR (elt,
			   Fcons (XCAR (tem), XCDR (tem)));
		  elt = XCDR (elt);
		  tem = XCAR (elt);
		  if (CONSP (tem) && EQ (XCAR (tem), Qkeymap))
		    XSETCAR (elt, Fcopy_keymap (tem));
		  tem = XCDR (elt);
		  if (CONSP (tem) && CONSP (XCAR (tem)))
		    /* Delete cache for key equivalences.  */
		    XSETCDR (elt, XCDR (tem));
		}
	    }
	  else
	    {
	      /* It may be an old fomat menu item.
		 Skip the optional menu string.
	      */
	      if (STRINGP (XCAR (tem)))
		{
		  /* Copy the cell, since copy-alist didn't go this deep.  */
		  XSETCDR (elt,
			   Fcons (XCAR (tem), XCDR (tem)));
		  elt = XCDR (elt);
		  tem = XCDR (elt);
		  /* Also skip the optional menu help string.  */
		  if (CONSP (tem) && STRINGP (XCAR (tem)))
		    {
		      XSETCDR (elt,
			       Fcons (XCAR (tem), XCDR (tem)));
		      elt = XCDR (elt);
		      tem = XCDR (elt);
		    }
		  /* There may also be a list that caches key equivalences.
		     Just delete it for the new keymap.  */
		  if (CONSP (tem)
		      && CONSP (XCAR (tem))
		      && (NILP (XCAR (XCAR (tem)))
			  || VECTORP (XCAR (XCAR (tem)))))
		    XSETCDR (elt, XCDR (tem));
		}