Xref: utzoo comp.lang.lisp:688 comp.lang.misc:1004
Path: utzoo!mnetor!uunet!umix!umich!dwt
From: dwt@zippy.eecs.umich.edu (David West)
Newsgroups: comp.lang.lisp,comp.lang.misc
Subject: Re: Hierarchical Browsers
Message-ID: <747@zippy.eecs.umich.edu>
Date: 27 Jan 88 17:47:27 GMT
Organization: University of Michigan EECS Dept., Ann Arbor
Lines: 22
Keywords: syntax-directed display

In a recent posting, I asked for (pointers to) info on writing hierarchical 
browsers, with particular reference to efficient screen updating. I should 
perhaps have been a little clearer; what I am interested in is an interactive 
syntax-directed source code viewer that lets one control the amount of detail 
visible at various levels of nesting, so that more context is visible. 
for example an if-then-else that might occupy more than a single screen could 
be displayed as  
	if <boolexp> 
	then <stmts> 
	else <stmts>
with the contents of the <boolexp> or the <stmts> optionally displayable in
the same style.  A fisheye viewer is a variant of this in which the level
of detail displayed depends on a more general quantity than just depth of
nesting.  A (syntax-directed) viewer is presumably much simpler to write than 
a (syntax-directed) editor, and could be almost as useful.  In fact, I'm
surprised someone hasn't posted one to comp.sources.* already.
(I don't know enough about Emacs; does it do this? For different languages?
If so, is there a way to find out how it's done without reading the entire
GNU Emacs source, which I don't even have?)
Please reply by email, and I'll summarize if there's interest and enough info.

-David West    dwt@zippy.eecs.umich.edu