Right now this is true: binary <file-reader> stream-seekable?
But none of the decoders allow stream-seeking. Maybe we should support that for ascii and other 8-bit encodings... On Sun, Nov 22, 2020 at 3:17 PM Jon Harper <jon.harpe...@gmail.com> wrote: > I didn't know about the seekable streams implementation in factor: > https://docs.factorcode.org/content/article-stream-protocol.html > > We have: > "/tmp/toto" ascii <file-reader> stream-seekable? > f > > "/tmp/toto" (file-reader) > t > ! it works, stream-seek can rewind or fast forward and stream-read1 > will get the bytes > > For some variable length encodings (utf8), seeking is going to be > pretty expensive, but for ascii it's transparent so maybe it should > work in <file-reader> ? > > Anyway you're right, although the peg vocabulary currently uses the > sequence protocol (mainly through slices from what I see), maybe it > could be rewritten to use the seekable stream protocol ? Still seems > like quite a lot of work though. > > Jon > > On Sat, Nov 21, 2020 at 11:49 PM Alexander Ilin <ajs...@yandex.ru> wrote: > > > > What's the problem backtracking through a file? Streams can have > arbitrary positioning. > > > > Alternatively, there must be a simple way to "wrap" a random access file > stream with an array-like interface, right? Don't we have a class like that > somewhere? > > > > Like the reverse of <string-reader> and <byte-reader>? > > > > I will definitely use the tokenizers, thanks. > > > > 22.11.2020, 01:34, "Jon Harper" <jon.harpe...@gmail.com>: > > > > What you are describing reminds me of the built-in nesting of parsers > with the ebnf tokenizer : > https://docs.factorcode.org/content/article-peg.ebnf.tokenizers.html > > > > Not sure if it's really applicable to your use case though. > > > > > > As for streams, aren't packrat parsers backtracking (with memoization)? > So no? > > > > > > > > _______________________________________________ > > Factor-talk mailing list > > Factor-talk@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/factor-talk > > > _______________________________________________ > Factor-talk mailing list > Factor-talk@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/factor-talk >
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