On Thu, Jun 2, 2011 at 7:02 AM, Yitzchak Gale <g...@sefer.org> wrote:
> It seems the best I can do is to collect them all in a list and then > apply concat. But that still copies the text several times. > Right. I'd like a no-copy combinator for the same reasons, but I think it's impossible to do without some low-level support. > If not, does the internal representation easily admit such a combinator? > Not very easily. Internally, attoparsec maintains just three pieces of data for its state: - The current input - Any input we received via continuations, in case we need to backtrack - A flag that denotes whether we were fed EOF by a continuation There are no line numbers, no "bytes consumed" counters, nothing else. If there was a "bytes consumed" counter, it would be possible to write a "try"-like combinator that would hold onto the current input, run a parser, tack on any input received via continuations to the original input, and then use the counter to slice off a portion of that bytestring without copying. I can't think of another way to do it. Adding that counter would be a moderate amount of work, and would presumably have a negative effect on performance.
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