" squeeze -- squeeze blank lines
" 
" $Id: squeeze,v 1.1 1997/05/29 20:51:39 cdua Exp cdua $
" Carlos Duarte, 970221
" 
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"	usage: _S
"
"	_S	squeeze all consecutive blank lines into one
"		setup each line with `_EJ' for empty ones, and 
"		`_Fj' for nonempty (F - fill), and the last
"		one gets `_Lj'.
"		the first two chars are the name of the macro
"		to run
"		the third is the command the the above line
"		will execute, if it is empty
"		
"		goto first, execute _R
"
"	_R	fetch the name of the macro to run into "d
"		and run it, also clean the third char (only
"		the 3rd char of the line below matters)
"
"	_F	macro for non empty lines
"		just down one line and run _R again
"
"	_L	last line, clean up extra line added by _S
"		don't call _R so stop here
"
"	_E	fetch the third char of the line below, and 
"		execute it from this line, execute _R again
"
"		if line below is empty, then the fetch char is
"		a `J', i.e. apply `J' to this empty line so 
"		delete it 
"
"		if line below is non empty, the fetch `j', i.e.
"		keep this line empty as wanted
"
"	
map _S :g/./s/^/_Fj/
:v/./s/^/_EJ/
Go_Lj1G_R
map _R 0"d2xx@d
map _E j2l"sylk@s_R
map _F j_R
map _L dd
"
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" 
" NOTE: 
" 	This is the only true squeezer I know for VI.
" 	The classical widespread `:v/./.,/./-1join' 
" 	simple doesn't work as we might expect!
" 
" 	First, if there are empty lines at bottom, they
" 	will get as they are-- no changes, and yet an
" 	error report: 
" 		if wrapscan on: error 1st addr exceeds 2nd
" 		else: error reach eof without finding...
" 
" 	Second, this may wipe out single empty lines. If
" 	a single empty line is found, the cmd performed
" 	is equiv to `.,.join' on that line -- this: 
" 
" 		on nvi 1.79, elvis 2.00, vile 6.0 (unix)
" 			delete it
" 
" 		on vim 4.5
" 			keep it
" 
" 	VIM's behavior is the most logical, as for what is
" 	correct, historically or POSIX, I really don't know
" 	and probably VIM should have an option or more to
" 	flag this event. 
" 
" 	But the important is that single lines will be deleted
" 	unsing at least three popular versions of vi.
" 
" 	So, this macros provides the only builtin vi method
" 	of squeezing line, of course `:%!cat -s' is so simpler...
"