Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!ll-xn!mit-eddie!husc6!hao!oddjob!gargoyle!ihnp4!cbosgd!mandrill!hal!ncoast!axcess!allbery
From: allbery@axcess.UUCP (Brandon S. Allbery)
Newsgroups: comp.emacs
Subject: Re: Hiding comments in C mode
Message-ID: <143@axcess.UUCP>
Date: 28 Jan 88 14:00:43 GMT
References: <8801202039.AA09434@ucbvax.Berkeley.EDU>
Organization: aXcess Company, Mentor, Ohio
Lines: 37
Summary: I see a generalization of selective-display here....

In article <8801202039.AA09434@ucbvax.Berkeley.EDU>, dsill@NSWC-OAS.ARPA (Dave Sill) writes:
+---------------
| the future of computing.  One person mentioned something about editors
| being able to hide comments on command.  How hard would it be to add
| this feature to GNU's C mode?  It sure would be handy, and a boon to
| readability, to be able to compress comments into /**/.  Kinda like
| outline mode...
+---------------

My "yacc" mode would benefit from being able to selective-display out stuff
between matched { } as well.

My thoughts on this -- no idea how implementable -- is to teach Emacs about a
standard way of handling paired strings.  A list "matched-string-list" could
be used to define these:

(("{" "}" t) ("(" ")" t) ("/*" "*/" nil) ("[" "]" t) ("\"" "\"" nil))

The list is made up of lists of (open-string, close-string, nest-flag).  The
nest-flag is "t" if the balanced strings can balance with themselves and with
other balancing strings; "nil" means the strings don't balance with themselves
and Emacs should balance other strings only within the current pair of strings
(i.e. a parenthesis inside a comment or string should never try to balance a
parenthesis outside the comment or string).  This would replace the current
implementation as part of the syntax table (the current way of handling e.g. C
comments looks like a kluge to me!).

Now for selective-display:  it is currently defined for "t"/"nil" or a number,
I would like it to take one of these matched-string-lists, and hide everything
between the balanced strings.

How doable is this?  I assume it has to be C code.
-- 
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