XText 0.9

	Introduction	
	
	I was unhappy to discover after switching from my
NeXTStation to an Intel P5 running NeXTStep that  XText 0.8
broke.  This is because version 0.8 uses keyboard specific  "key
codes". 
	
	XText 0.9 is a hardware independent version of XText,
with a few extra goodies thrown in for fun.  It uses "character
codes", which are NeXT/Adobe's generalization of ASCII codes.
XText reads character codes from keyboard events and 
allows the user considerable flexability in redefining keystrokes.
This is achieved by Mike Dixon's remarkable "action parsing"
code, where text strings are convered into  XText method calls.

	XText 0.8 was written by Mike Dixon:  
	
	Mike Dixon
	Xerox PARC
	3333 Coyote Hill Rd.
	Palo Alto, CA 94304
	mdixon@parc.xerox.com

Much of the discussion below is based on the original XText0.8 
;XText0.8.rtf;;¬README file.   Major changes to XText are:

	a. An expanded version of XTDemo saves keybinding files,
	and XText reads keybinding files.
	
	b. Hardware independent modifiers:
	
		l = NX_ALPHASHIFTMASK
			Alpha Lock is set and Shift key is NOT* down
		s = NX_SHIFTMASK
			a shift key is down
		c = NX_CONTROLMASK
		 	Control key is down
		a = NX_ALTERNATEMASK
			Alternate key is down
		m = NX_COMMANDMASK
			Command key is down
		n = NX_NUMERICPADMASK
			Key is on numeric keypad
		h = NX_HELPMASK
			Help Key

	c. 	Keycodes can be entered by Capitalized HEX
		numbers.

	Basic Concepts
	
	XText lets users execute complex text editing and formating
commands by redefining  keystrokes.  It does this by  letting the
user associate, for every key, text object methods.  For
example, to associate the "control a" key with the  method
	
		[xtext replaceSel:"Hello World\n"]; 
		
	The user, or application programmer, constructs a keybinding format
	
		c'a = replaceSel: "Hello World\n"'

	XText can parse, in this way,  methods with at most two
arguments, which must be either integers or strings.  XText
has an expanded set of useful methods, that give users  "emacs
like" control over their keystrokes.  The expanded list is given
below.  
	
	XText enables programmers to easily incorporate this 
keyboard functionality into their applications.   Keybindings
can be loaded at run time,  using an XText method which
parses strings of keybindings, or (new to version 0.9) a method
which reads a file of keybinding strings.  The file reader method
was added to work with the concept of an application wrapper.
(That is, programmers can save keybindings as a file  in their  .app
directory.)  

	XText 0.9 methods for keybindings
	
	The following methods were written for easy keybinding
	construction.   All of the cursor-movement methods take a 
	`mode' argument,  which may be

		0		just move the point to new location
		1		delete to new location
		2		cut to new location
		3		extend selection to new location

	The methods for cursor-movement are:

	goto:end:mode:		implements all movement; second argument specifies 
		the other end of the selection when mode != 0

	moveWord:mode:		move n words forward from point (back if n<0)

	moveChar:mode:		move n chars forward from point (back if n<0)

	moveLine:mode:		move n lines down from point (up if n<0)

	lineBegin:			move to beginning of current line

	lineEnd:	
		move to end of current line

	docBegin:			move to beginning of document

	docEnd:				move to end of document

	collapseSel:		move to beginning of selection (dir<0), end of		selection (dir>0), or active end of sel (dir=0)

	transChars			transpose characters around point

	openLine				insert new line after point

	scroll::			scroll window n pages + m lines
		
	scrollIfRO::		scroll window n pages + m lines if doc is		read-only; returns nil if doc is editable
		
	insertChar:		inserts the character associated with a key event
		
	insertNextChar		sets nextAction so that the next key event will be		interpreted as a character
	
	Methods for c program formatting:
	
	autoIndent
		creates a new line with space and tab indentation
		equal to the current line
		
	match:"LR";
		Finds previous correctly nested matched character L and
		briefly displays it; then prints R.  Useful for "()" "{}"
		and "[]".   

	Character Codes
	
	Keyboard independent character codes which XText 0.9 uses
	are constructed using simple rules.  They can be found in the 
	insertKeyCombination: method of XText.
		
	a. Type the following characters to denote modifier keys:
		c	control key down, 
		s	shift key down, 
		a	alt key down,  
		m	command key down,
		n	a numeric keypad character, on my `101' keyboard, the
		 	arrow keys and the keypad,
		l 	caps-lock  key down,  and shift key NOT pressed,
		h 	help key down
		
	      Note: Use "l" if you want a charater code to 
		  be active only if the caps-lock key is down.  Other 
		  character codes work with the caps-lock key 
		  on or off.
		   
	b.	Add the '  (right quote) key to denote the beginning of the 
		actual key.
	
	c.  If the key will print,  type it.  

	Note:  Alt characters are generally mapped to the 
	upper 127 chacters of the Adobe/NeXT extended character
	set.  Being non-ASCII characters, they look unusual. 
	
	d.  If it a non-printing character like space, tab, or return, type
		its hexadecimal character code.  Character codes are found 
		in Appendix C of the AppKit Documentation (Figure C1).
		
	e. Hexadecimal  codes are denoted by the characters 1-9, A-F.
	    (The uppercase in the hex numbering is important.)

	f.  If it is a control character, type the key of the character; i.e.
		"control a" = c'a, "control shift A" = cs'A etc.
		
	Binding Specifications (Putting it all together)	
	A binding spec is a comma separated list of key codes, 
	followed by an equal sign,  followed by an action (a method
	above with input data). For example, 
	
	c'w, a'ã = moveWord:-1 mode:1
	(control w and alt h = delete last word)
	
	c'b=moveChar:-1 mode:0; c'B=moveChar:-1 mode:3

	Comment lines in the example files below begin with `#' 

	;arrow.keys.rtf;arrow.keys;¬arrow.keys
	;emacs.keys.rtf;emacs.keys;¬emacs.keys
	;keypad.keys.rtf;keypad.keys;¬keypad.keys
	;programmer.keys.rtf;programmer.keys;¬programmer.keys
	;readonly.keys.rtf;readonly.keys;¬readonly.keys

	Program Implimentation 
	
	1.  Copy the XText subproject into your application.  
	Include the line 
	
	#import "XText.subproj/XText.h"
	
	In files that create XText and XTScroller  objects. 

	2. Occurrences of [Text alloc] must be replaced with 
	
	[XText alloc].  
	
	If you're using IB to construct your Text
	objects it currently provides no clean way to make a 	ScrollView containing something other than a Text, so
	there is a support class XTScroller that provides just that --
	simply replace your ScrollViews with XTScroller custom
	views and the XTexts will be constructed automatically.
	These newly-created XText objects will behave just like
	Text objects; in particular, they will have no key bindings.. 

	3a. Initialize an "action", which stores and parses 
	(interprets strings into method calls) keybindings:
		
	demoAction = 
	[[XTDispatchAction alloc] init];
		
	3b. Or initialize using a default keybinding table:
	
		action = [[XTDispatchAction alloc]
		initBase:NXGetDefaultValue("myApp",
		"KeyBase") estream:nil];
		
		(NOTE: in XText0.9, the emacs table
		has been removed.  The advent of 
		".app" wrappers in NS 3.0 makes 
		storage of keybindings as files
		in application directories a much
		more elegant approach.  See 4b below.) 
		
	4a. Add any dwrite type user-defined bindings
		
		[action addBindings:
		NXGetDefaultValue("myApp", "KeyString") 
		estream:nil];

	4b. Or add any file of user-defined bindings.
	
		[action loadFromFile:
		NXGetDefaultValue("myApp", "KeyFile") 		estream:errs];
	
	loads bindings from a file.  Comments are lines in the 	file beginning with `#'.  This method enables developers 
	to load keybinding files from their .app wrapper 	directories, via 

		[[NXBundle mainBundle] 
				getPath:path 
				forResource:"KeyBindingFiles"
				ofType:""];

	5.  Attach the action to the text object.
	
	[myXText setInitalAction:action];
	
	6. See XTDemo.app  for more example code.

	;XText.rtfd;format;¬The Format of Binding Specifications
		
	The format used to specify bindings is:

	A binding spec is a sequence of zero or more bindings,  
	separated by `;'s

	A binding is a key spec, followed by an `=', followed by an
	 action

	A key spec is a sequence of one or more key combinations,
	 separated by `,'s

	A key combination is a sequence of zero or more modifiers,
	 followed by a key
	
	A modifier is 
	c	(control), 
	s	(shift), 
	a	(alt),  
	m	(command),
	n	(numeric keypad),
	l 	(caps-lock),
	h 	(help key)
	
	A key is a `'' followed by any character (designates the key
	 that generates that character), or a 2-digit hex key code, as
	 documented  in
		
	NextLibrary/Documentation/NextDev/GeneralRef/
	_ApC_KeyboardEvents/KeyInfo.rtfd
	
	An action is a message, or a sequence of actions separated by
	 `;'s and enclosed in `{}'s
	
	A message is something like 
	`moveWord:-1 mode:1'   or 
	`replaceSel: "hi there\n"'
	(at most two arguments, which must be either integers or
	 strings)
	
	Paul Griffin, 7/95