Mac: modifier key remapping revised [patch]

[David Reitter <david.reitter@gmail.com>]

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Hi,

the current state of affairs makes it difficult to map the standard Mac 
modifier keys (Ctrl, Option, Command) to Emacs modifiers.

At this point, the default is that the command key is Meta, but by 
setting mac-command-key-is-meta to nil, one can map Option to Meta.
An additional variable, mac-reverse-ctrl-meta, allows to swap Ctrl and 
(whatever is) Meta.
Finally, a patch introduced in November last year allows us to map 
Option to whatever (e.g. Hyper or Meta) via the variable 
mac-option-modifier.

This is complicated, and in effect does not allow me to map, for 
example Command to Hyper, which makes a lot of sense if you want to 
assign something to Command-X, without overriding M-x (or A-x) and 
without consequences for the choice of Option.

Therefore I suggest to a) deprecate mac-command-key-is-meta and 
mac-reverse-ctrl-meta, and b) introduce mac-control-modifier and 
mac-command-modifier which allow, analogous to the recent 
mac-option-modifier, free mapping of the modifier keys.

All of a sudden, the modifier key business becomes simple and 
straightforward:

(setq mac-option-modifier 'meta)
(setq mac-control-modifier 'ctrl)
(setq mac-command-modifier 'hyper)

In order to preserve backwards-compatibility, the two deprecated 
variables remain in effect unless at least one of the above 
mac-*-modifier variables is set to non-nil.
Problems should only occur if somebody uses the old mac-option-modifier 
in combination with the deprecated variables; but the option variable 
has been introduced only recently and hasn't seen significant uptake 
yet (google it!).

The attached patch implements this behavior, it applies against today's 
catch (of macterm.c).


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Index: macterm.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/macterm.c,v
retrieving revision 1.111
diff -r1.111 macterm.c
89,91c89,99
< /* Set of macros that handle mapping of Mac modifier keys to emacs.  */
< #define macCtrlKey     (NILP (Vmac_reverse_ctrl_meta) ? controlKey :	\
< 			(NILP (Vmac_command_key_is_meta) ? optionKey : cmdKey))
---
> /* Set of macros that handle mapping of Mac modifier keys to emacs.  
>    If any of the newer-style mac_*_modifier variables is set, these macros are basically out of function,
>    they just map to the normal keys - except for Meta, which is then (ESC or) command-control-option.
> */
> 
> #define macOldModifierSetting   (  NILP(Vmac_control_modifier) && NILP(Vmac_option_modifier) && NILP(Vmac_command_modifier)   )
> 
> #define macCtrlKey     (macOldModifierSetting ? \
> 			(NILP(Vmac_reverse_ctrl_meta) ? controlKey :	\
> 			       (NILP(Vmac_command_key_is_meta) ? optionKey : cmdKey)) : \
> 			controlKey)
93,96c101,109
< #define macMetaKey     (NILP (Vmac_reverse_ctrl_meta) ?			\
< 			(NILP (Vmac_command_key_is_meta) ? optionKey : cmdKey) \
< 			: controlKey)
< #define macAltKey      (NILP (Vmac_command_key_is_meta) ? cmdKey : optionKey)
---
> 
> #define macMetaKey     (macOldModifierSetting ? \
> 			(NILP(Vmac_reverse_ctrl_meta) ?		\
> 			 (NILP(Vmac_command_key_is_meta) ? optionKey : cmdKey) : controlKey) : \
> 			(cmdKey | controlKey | optionKey))
> 
> #define macAltKey     (macOldModifierSetting ?  (NILP(Vmac_command_key_is_meta) ? cmdKey : optionKey) : optionKey)
> 
> #define macCmdKey (cmdKey)
98a112
> 
241c255
< static Lisp_Object Qalt, Qhyper, Qsuper, Qmodifier_value;
---
> static Lisp_Object Qalt, Qhyper, Qsuper, Qctrl, Qmeta, Qmodifier_value;
7195c7209,7210
< /* True if using command key as meta key.  */
---
> /* True if using command key as meta key.  
>    Deprecated; only use if macOldModifierSetting evaluates to true. */
7197a7213,7215
> /* Modifier associated with the control key, or nil for normal behavior. */
> Lisp_Object Vmac_control_modifier;
> 
7201c7219,7223
< /* True if the ctrl and meta keys should be reversed.  */
---
> /* Modifier associated with the command key, or nil for normal behavior. */
> Lisp_Object Vmac_command_modifier;
> 
> /* True if the ctrl and meta keys should be reversed. 
> 	Deprecated; only use if macOldModifierSetting evaluates to true. */
7276,7284c7298,7313
<   if (mods & macCtrlKey)
<     result |= ctrl_modifier;
<   if (mods & macMetaKey)
<     result |= meta_modifier;
<   if (NILP (Vmac_command_key_is_meta) && (mods & macAltKey))
<     result |= alt_modifier;
<   if (!NILP (Vmac_option_modifier) && (mods & optionKey)) {
<       Lisp_Object val = Fget(Vmac_option_modifier, Qmodifier_value);
<       if (!NILP(val))
---
> 
>  if (macOldModifierSetting)     /* compatibility with old-style modifier keys */
>     {
>       if (mods & macCtrlKey)
> 	result |= ctrl_modifier;
>       if (mods & macMetaKey)
> 	result |= meta_modifier;
> 
>       if ( NILP (Vmac_command_key_is_meta) && (mods & macAltKey) )
> 	result |= alt_modifier;
>     } else
>     {
>       /* new-style modifier keys */ 
>       if (!NILP (Vmac_option_modifier) && (mods & optionKey)) {
> 	Lisp_Object val = Fget(Vmac_option_modifier, Qmodifier_value);
> 	if (!NILP(val))
7286c7315,7335
<   }
---
>       } else { /* default behavior if modifier variable is not set */
> 	if (mods & macAltKey)
> 	  result |= alt_modifier;
>       }
>       if (!NILP (Vmac_command_modifier) && (mods & cmdKey)) {
> 	Lisp_Object val = Fget(Vmac_command_modifier, Qmodifier_value);
> 	if (!NILP(val))
>           result |= XUINT(val);
>       } else { /* default behavior if modifier variable is not set: assign hyper*/
> 	if (mods & macCmdKey)
> 	  result |= hyper_modifier;
>       }
>       if (!NILP (Vmac_control_modifier) && (mods & controlKey)) {
> 	Lisp_Object val = Fget(Vmac_control_modifier, Qmodifier_value);
> 	if (!NILP(val))
>           result |= XUINT(val);
>       } else { /* default behavior if modifier variable is not set */
> 	if (mods & macCtrlKey)
> 	  result |= ctrl_modifier;
>       }
>     }
9059,9061c9108,9110
< 		if (er.modifiers & (controlKey |
< 				    (NILP (Vmac_command_key_is_meta) ? optionKey
< 				     : cmdKey)))
---
> 		if  (er.modifiers & (controlKey |
> 		      ((macOldModifierSetting && NILP (Vmac_command_key_is_meta)) ? 
>                                          optionKey : cmdKey)))
9078,9079c9127,9128
< 		else if (!NILP (Vmac_option_modifier)
< 			 && (er.modifiers & optionKey))
---
> 		else if (!macOldModifierSetting
> 			 && (er.modifiers & (optionKey | controlKey | cmdKey)  ))
9081c9130
< 		    /* When using the option key as an emacs modifier,
---
> 		    /* When using a key as an emacs modifier,
9083,9084c9132,9138
< 		       without the Mac option modifier applied. */
< 		    int new_modifiers = er.modifiers & ~optionKey;
---
> 		       without the Mac  modifier applied. 
> 
> 		       Could we do something like 
> 		       new_modifiers = er.modifiers & shiftKey 
> 		       instead?
> 		    */
> 		    int new_modifiers = er.modifiers & ~controlKey & ~optionKey & ~cmdKey;
9090,9092c9144,9146
< 		  }
< 		else
< 		  inev.code = er.message & charCodeMask;
---
> 		  } else
> 		     inev.code = er.message & charCodeMask;
> 
9096c9150
< 
---
> 	  
9789a9844,9847
>   Qctrl = intern ("ctrl");
>   Fput (Qctrl, Qmodifier_value, make_number (ctrl_modifier));
>   Qmeta = intern ("meta");
>   Fput (Qmeta, Qmodifier_value, make_number (meta_modifier)); 
9839a9898,9900
> /* Deprecated variables to configure modifier key assignment.
> 	Retained for backward-compatibility. */
> 	
9842c9903,9904
< Otherwise the option key is used.  */);
---
> Otherwise the option key is used. This variable is DEPRECATED. 
> It is only in effect if all of the variables mac-*-modifier are nil. */);
9843a9906,9923
>   
>   DEFVAR_LISP ("mac-reverse-ctrl-meta", &Vmac_reverse_ctrl_meta,
>     doc: /* Non-nil means that the control and meta keys are reversed.  This is
> useful for non-standard keyboard layouts. This variable is DEPRECATED. 
> It is only in effect if none of the variables mac-*-modifier is non-nil. */);
>   Vmac_reverse_ctrl_meta = Qnil;
> 
> 
> /* Variables to configure modifier key assignment.  */
> 	
>   DEFVAR_LISP ("mac-control-modifier", &Vmac_control_modifier,
>     doc: /* Modifier to use for the Mac control key.  The value can
> be alt, hyper, or super for the respective modifier.  If the value is
> nil then the key will act as the normal Mac control modifier.  However, if all
> values of mac-{command|control|option}-modifier are nil, the deprecated
> default assignment determined by mac-command-key-is-meta and
> mac-reverse-ctrl-meta is used. */);
>   Vmac_control_modifier = Qnil;
9848c9928,9931
< nil then the key will act as the normal Mac option modifier.  */);
---
> nil then the key will act as the normal Mac option modifier. However, if all
> values of mac-{command|control|option}-modifier are nil, the deprecated
> default assignment determined by mac-command-key-is-meta and
> mac-reverse-ctrl-meta is used.  */);
9851,9854c9934,9941
<   DEFVAR_LISP ("mac-reverse-ctrl-meta", &Vmac_reverse_ctrl_meta,
<     doc: /* Non-nil means that the control and meta keys are reversed.  This is
< useful for non-standard keyboard layouts.  */);
<   Vmac_reverse_ctrl_meta = Qnil;
---
>   DEFVAR_LISP ("mac-command-modifier", &Vmac_command_modifier,
>     doc: /* Modifier to use for the Mac command key.  The value can
> be alt, hyper, or super for the respective modifier. If the value is
> nil then the key will act as the normal Mac option modifier. However, if all
> values of mac-{command|control|option}-modifier are nil, the deprecated
> default assignment determined by mac-command-key-is-meta and
> mac-reverse-ctrl-meta is used.  */);
>   Vmac_command_modifier = Qnil;

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