Path: utzoo!utgpu!water!watmath!clyde!burl!codas!ufcsv!gatech!udel!rochester!quiroz
From: quiroz@cs.rochester.edu (Cesar Quiroz)
Newsgroups: comp.emacs
Subject: Re: Emulating TECO paging in EMACS
Summary: Narrow to page?
Message-ID: <5872@sol.ARPA>
Date: 14 Jan 88 00:30:25 GMT
References: <772@softg.UUCP>
Reply-To: quiroz@ROCHESTER.UUCP (Cesar Quiroz)
Organization: U of Rochester, CS Dept, Rochester, NY
Lines: 33
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From article <772@softg.UUCP> (dana@softg.UUCP (Eric Dana)):
:Recently I have been working on a project to convert TOPS-20
:TECO macros to EMACS Lisp. One of the requirements is to read
:(or yank) in a page of an input file at a time. Even though
:EMACS (18.49) can handle paging in a buffer, I cannot find a
:way to get the page from the input file into the buffer.
:Can anyone help? Thanks in advance.

There are no functions to deal with I/O directly (this is a `to do',
of course).  Perhaps the best approximation with the available
functionality would be:

    1-  Read the whole file into a buffer, put point at the very
        beginning.

    2-  Narrow to the first page.  Do not use narrow-to-page, but
        use the motion commands to find where the page ends.

    3-  On a Y, just change the restriction to the next page.

    4-  On A, narrow-to-page is no good.  You have to compute the
        extent of the new restriction, and do the narrowing
        yourself.

In this way your buffer is always restricted to a number of entire
pages, just those TECO believed were in its buffer.  No more 3K
restrictions, of course...

-- 
Cesar Augusto  Quiroz Gonzalez
Department of Computer Science     ...allegra!rochester!quiroz
University of Rochester            or
Rochester,  NY 14627               quiroz@cs.rochester.edu