From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Thread: 103376,b5cd7bf26d091c6f X-Google-NewGroupId: yes X-Google-Attributes: gida07f3367d7,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII X-FeedAbuse: http://nntpfeed.proxad.net/abuse.pl feeded by 88.191.131.2 Path: g2news1.google.com!news4.google.com!proxad.net!feeder1-2.proxad.net!nntpfeed.proxad.net!news.dougwise.org!usenet.pasdenom.info!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Reading the while standard input into a String Date: Mon, 6 Jun 2011 20:53:27 +0200 Organization: cbb software GmbH Message-ID: References: <1e5e764d-eb7b-4804-8119-b535ddbe5e7e@32g2000vbe.googlegroups.com> <1a84tm53l1wjx.1xdgsbp25vyd5.dlg@40tude.net> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: 6an/HxOXjVOykPvLkSpw3Q.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8bit X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 Xref: g2news1.google.com comp.lang.ada:19649 Date: 2011-06-06T20:53:27+02:00 List-Id: On Mon, 6 Jun 2011 11:36:00 -0700 (PDT), Maciej Sobczak wrote: > On Jun 6, 8:18�pm, "Dmitry A. Kazakov" > wrote: > >>> This is a can of warms - how big should be that chunk? :-) >> >> For a compiler it is the maximal length of look ahead / roll-back, >> normally, less than just one line. > > This is wrong even for Ada. Of course it is possible for Ada, of which syntax requires neither look ahead or roll-back. > BTW - what about generating debug version of the executable with > source embedded? What for? All you need is source location tags. >>> Or not. System calls are relatively expensive - typically much more >>> expensive than copying data around. For this reason wisely used >>> additional buffers can improve performance of I/O operations. >> >> The opposite is also possible, unless the OS driver uses user-space >> buffers. So I would follow Ludovic's advise, especially in the case of a >> compiler where reading overhead is negligible comparing to other >> computations per character. > > There is no point in following this advice, because compiler is not > cat or grep. That is another argument, first we agree that performance is not an issue here. > In particular, the compiler does not work on potentially > infinite streams (unlike cat and grep) and there is a clear concept of > a program structure that has its end. This means that reading the > whole source file into memory is a perfectly valid approach. Wrong. A good example is GNAT compiler which runs out of Windows' 1-2GB limit when compiling my generics. Macros tend to explode (:-)) Memory is cheap, but that does not mean you should waste it. You just do not need to keep anything but the current source line. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de