0README

./scrunch
|-- 0NOTE			port to mac os x from irix: lex differences
|-- 0Postings			directory - statement of problem; responses ....
|   |-- postings.txt			text file summary of postings
|   `-- scrunch-[12]-[12].html		3 html files of postings
|-- 0README			this file
|-- Lex-trials			direcetory - different lex solutions to problem
|-- Makefile			to test awk and lex solutions, run: make test
|-- scrunchAwk			awk solution of problem - (stephen peckham)
|-- scrunchLex.l		lex solution - (john rupley)
`-- scrunchLex.l.irix		irix version, ported to mac os x as above file


STATEMENT OF PROBLEM: scrunch cpp output to make it more readable.

Compress runs of "#" lines and blank lines, or runs of two or more
blank lines:

	(\n*# lineno "file"\n+)+  or  \n\n+

into a single line:

	# lineno "file"\n

which is output before the next line of program text (corresponding to
line "lineno" of the source "file").  The values of "lineno" and "file"
are adjusted for changes in source resulting from #include statements.



Two solutions: an awk version (by Stephen Peckham) and a Lex version
(by myself).

Both solutions are comparably simple.  Here the character-stream processing
of Lex has no advantage over the line-oriented processing of awk. 
Thus, IMHO, awk is preferable.  
C-code or sed-script solutions would be more complicated.


awk solution (#From: peckham@svax.cs.cornell.edu (Stephen Peckham):

	awk '
	{if (NF == 0) blanks++
	 else if ($1=="#") {l_no = $2-1; f = $3; blanks = 2;}
	 else {
		if (blanks > 1) print "#", l_no, f;
		else if (blanks == 1) print "";
		blanks = 0;
		print $0;
	      }
	 l_no++;
	}'


lex solution (John Rupley  rupley!local@cs.arizona.edu):

	%}
		char f[2048]; int x; int xxlineno;
	W	[ \t]*\n
	%%
	#.+\n		{sscanf(yytext,"#%d%s",&xxlineno,f); x++;}
	{W}/{W}|#	x++; xxlineno++;
	{W}		if(!x) ECHO; xxlineno++;
	.+\n	{if(x) printf("# %d %s\n",xxlineno,f); ECHO; xxlineno++; x=0;}



To test the solutions, run:

	make clean
	make test

The test consists of (see Makefile):

	1. creating a test cpp file from the lex program output, lex.yy.c
	(lex.yy.c is compiled with gcc to give the lex executable);

	2. then "scrunching" the cpp file with the awk or the lex
	executable, and comparing the scrunched outputs (no significant
	differences);

	3. finally, showing that the scrunched output is "good",
	i.e., it will compile to give a working executable identical
	in operation to the lex or awk executables.


For discussion, see the comp.lang.c postings:
	0Postings/postings.txt
or, more readable,
	scrunch-1-1.html
	scrunch-2-[12].html


John Rupley
 rupley@u.arizona.edu -or- jar@rupley.com
 30 Calle Belleza, Tucson AZ 85716 - (520) 325-4533; fax - (520) 325-4991
 Dept. Biochemistry & Molecular Biophysics, Univ. Arizona, Tucson AZ 85721