random i/o tools

[snicoud@atc.boeing.com (Stephen L. Nicoud)]

    Date: 11 Jul 90 02:27:44 GMT
    From: barmar@Think.COM (Barry Margolin)


	Date: Tue, 10 Jul 90 16:57:09 MDT
	From: bein@boulder.Colorado.EDU (Jonathan Bein)

	Does anyone in the SLUG community have or know of Symbolics 
	software that can be used for doing random file i/o?  I am doing
	some database work and need tools for disk based hashing, B-trees, etc. 
	to integrate in the software I am developing.  I am aware that similar
	software components are available in Statiuc, but I need random i/o
	utilities that are not embeeded in a proprietary product.

    You can do random I/O with the standard stream I/O facilities in Genera.
    The Common Lisp FILE-POSITION function can be used on binary streams to
    go to any position in the file; this isn't permitted for character
    streams because character set translations and character style
    expansions make it difficult to determine the physical location in the
    file corresponding to a character position.

I think we have an application here that does a binary search on a file of
STRING-CHARs.  We gave these keyword options to OPEN: :direct t
:element-type 'string-char.  Then we used FILE-POSITION to move around.
The :direct keyword is a Symbolics extension, and therefore not portable
(well, at least it used not to be portable.

Steve