Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ig!arizona!rupley
From: rupley@arizona.edu (John Rupley)
Newsgroups: comp.lang.c
Subject: Re: Want a way to strip comments from a
Summary: Lex is a way; test file attached
Keywords: comment stipping Lex test file
Message-ID: <9778@megaron.arizona.edu>
Date: 18 Mar 89 01:38:19 GMT
References: <7150@siemens.UUCP> <9900010@bradley> <4896@cbnews.ATT.COM> <978@philmds.UUCP> <2131@mister-curious.sw.mcc.com>
Reply-To: rupley@arizona.edu (John Rupley)
Followup-To: comp.lang.c
Distribution: usa
Organization: U of Arizona CS Dept, Tucson
Lines: 61

In article <2131@mister-curious.sw.mcc.com>, loo@mister-curious.sw.mcc.com
(Joel Loo) writes:
> In article <978@philmds.UUCP>, leo@philmds.UUCP (Leo de Wit) writes:
> > And how about:
> >     puts(" A comment /* in here */");
> > And you can give more examples showing it isn't that trivial; a challenge
> > for the sed adept, perhaps ...
> >    Leo.
> [And a lot of previous articles on the same topic]
> 
> The problem is: sed and vi do not understand C syntax.
> 
> Solution: write a lex program to strip comments. The program must
> understand C syntax enough to know what is a comment and what is not.
> 
> Encouragement: it should not be too difficult.
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
It isn't.  Six lines of Lex source (not counting initialization) are 
enough. A Lex source for ``uncomment'' has been posted in comp.sources.unix,
as part of:
	Subject: Volume 16 (Ends January 17, 1989)
	identlist	List identifiers and declarations for C sources

Attached is a minimum test for an uncommenting algorithm, including
tests for quotes inside and outside comments.

John Rupley
 uucp: ..{uunet | ucbvax | cmcl2 | hao!ncar!noao}!arizona!rupley!local
 internet: rupley!local@megaron.arizona.edu
 (O) Dept. Biochemistry, Univ. Arizona, Tucson AZ 85721 - (602) 621-3929
----------------------------------------------------------------------------
/*
 * tests for ``uncomment''
 * assume C-code conventions:
 * 	strings start and end on one line
 * 	comments can be multi-line
 * no tests for varieties of:	'"'   \'"\'   etc
 * no tests for strings with newline escaped
 */
string4		"hi /*\"hi there*/there\""
comment1		/*one"*/"*/
comment2		/*\"hi there"*/"*/"
comment3		/*\"hi there*/
comment4		/* hello/*hello/*hello/*hello*/
comment5		/*******/
comment6		/*/*/ a /**/ b /***/ c /****/ d /*////*/
comment7		/*/*// a /**// b /***// c /****// d /*////*//

1. /*****//"hello world */"				ok   /"hello world */"
2. /* hello /* /* world */				ok	
3. /* */ hello /* */					ok	hello
4. /**// /* this should produce "/ \n" for output */	ok	/ 
5. /* */ hello */					ok	hello */
6. /*/*/ hello						ok	hello
7. /*////*/						ok	
8. /*//*/						ok	
9. abc = "/* fake comment"; /* got who ? */		ok	abc = "STRING";
10. /*   "start quote
	"then next line end quote, after more characters than on line 1"
	more more more */  "				ok	"
----------------------------------------------------------------------------