Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ncar!tank!uxc!uxc.cso.uiuc.edu!m.cs.uiuc.edu!wsmith
From: wsmith@m.cs.uiuc.edu
Newsgroups: comp.software-eng
Subject: Re: Structured Editor vs. Text Editor
Message-ID: <39400003@m.cs.uiuc.edu>
Date: 26 Oct 88 01:24:00 GMT
References: <3385@pt.cs.cmu.edu>
Lines: 34
Nf-ID: #R:pt.cs.cmu.edu:3385:m.cs.uiuc.edu:39400003:000:2103
Nf-From: m.cs.uiuc.edu!wsmith    Oct 25 20:24:00 1988


>There are two main idea for editors, I think.  One is a simple text editor,
>the other is a structured editor.  The structure editor will guarantee the
>result of editing is legal for the specific programming language, of course.
>So, in that point, it is superior to the simple text editor.  But, I feel
>most of the existing structure editors are not so friendly for me.  Say,
>when I want to move a cursor downward and to insert words, I may not do it
>straight in the structured editor.  How do you think?  I know, it may
>depend on programmers' taste.  Or, does anyone around there know the editor
>that has both characteristics of the text editor and those of the structured
>editor, i.e., in which we can move the cursor in the same way as in the text
>editor and which guarantees the result of editing are legal to the language?

My research group at the University of Illinois has written a language 
oriented editor, Leif, that has most of the characteristics you describe.  
First, the program may be edited with text editing commands and the text is
also analyzed to locate syntax errors.  Also, commands are available to select
syntactic elements of the program.  Leif may be targeted to several
different languages by writing a new specification in Bison and Lex.

I believe that guaranteeing that the result of the editing is legal in the
language is too strict.  When I am translating a program from one language to 
another, or performing a complex editing change, I often make the program 
syntactically incorrect but will the later correct the error.  Leif 
accomodates this desire by postponing its analysis until a request is made.  
The command move-to-error will find any syntactic errors and help correct
them.

Leif is available via anonymous FTP from a.cs.uiuc.edu (cd pub/Leif) and 
other arrangements are possible if FTP is impossible.
----------------------------------------------------------------------------
Bill Smith			|  Mail sent to leif@cs.uiuc.edu or 
wsmith@cs.uiuc.edu		|  uiucdcs!leif will go to our research group 
uiucdcs!wsmith			|  headed by Roy Campbell.