Re: io:lines() and 0円
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- Subject: Re: io:lines() and 0円
- From: Roberto Ierusalimschy <roberto@...>
- Date: 2014年2月18日 11:04:16 -0300
> I woud propose something like:
>
> [...]
ANSI C says that about text files:
Data read in from a text stream will necessarily compare equal to
the data that were earlier written out to that stream only if: the
data consist only of printing characters and the control characters
horizontal tab and new-line; no new-line character is immediately
preceded by space characters; and the last character is a new-line
character.
So, there is no garanties that a text file with embedded zeros will be
read correctly, no matter how we implement it.
> One of the strengths of C is the speed at what it can read a char and
> act on it ( or not act ). getc() is normally very fast. lual_addchar
> is very fast, for what I've seen in lualib.h. The speed loss should
> not be noticeable, and IMO not worrth the extra complexity in the
> current readline function. [...]
Just for the record: In my machine, the following program,
local count = 0
for l in io.lines() do
count = count + #l
end
print(count)
reading the Bible, takes ~0.07s with the current implementation and
~0.14s with this proposal.
-- Roberto