Re: Lua Performance, IO / Regexp
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- Subject: Re: Lua Performance, IO / Regexp
- From: Hans Hagen <pragma@...>
- Date: 2007年10月19日 01:32:49 +0200
Mariano Kamp wrote:
Any ideas and hints what I can do to make things faster and/or prettier?
- lpeg: much faster than string match
- no metatable: less code and less function calls (not faster here)
- binary read: no need to parse line endings in io
- the lpeg can probably be made faster (no time to look into it now)
testfile = "o.ap"
hits, hits_index = { }, { }
function whatever(ak) hits[ak] = (hits[ak] or 0) + 1 end
digit = lpeg.R("09")
pattern = (digit * digit * digit * digit * "/" * digit * digit * "/" *
digit * digit * "/" * (1-lpeg.S(" ."))^1) / whatever
prefix = "GET /ongoing/When/" * digit * digit * digit * "x/"
suffix = " "
newline = lpeg.S("\n\r")
complete = prefix * pattern * suffix
if true then
-- binary read 10% faster
parser = ((1-complete)^0 * complete * (1-newline)^0 * newline)^0
input_file = io.open(testfile,'rb')
parser:match(input_file:read("*all"))
input_file:close()
else
parser = (1-complete)^0 * complete
-- 4 times slower
for line in io.lines(testfile) do
parser:match(line)
end
end
for article_key in pairs(hits) do hits_index[#hits_index+1] =
article_key end
table.sort(hits_index, function(x,y) return hits[x] > hits[y] end)
for i, article_key in ipairs(hits_index) do
print(i .. ". " .. article_key .. " : " .. hits[article_key])
if i == 10 then break end
end
Hans
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Hans Hagen | PRAGMA ADE
Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
tel: 038 477 53 69 | fax: 038 477 53 74 | www.pragma-ade.com
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