Pattern matching - FAST code
Pattern matching example from a Well House Consultants training course
More on Pattern matching [link]
Source code: slander1 Module: U108
--[[ This is a pattern matching example that goes through
a data file of 43 Mbytes and finds all log file records which
are Google search engine arrivals.
In this (the faster of two example), I have matched section by
section to make the code run quickly - it turns out to be 1000
times faster than a starightforward single match. ]]
fh = io.open("ac_short")
running = true
mcount = 0
count = 0
while running do
line = fh:read()
if line ~= nil then
count = count + 1
n,m = string.find(line,'%.google%.')
if n ~= nil then
n,m,ip = string.find(line,'(%S+)')
n,m,query = string.find(line,'"http.-[&?]q=(.-)[&"]')
if query ~= nil then
mcount = mcount + 1
running = false
taken = os.clock()
print ("time taken in seconds - ",taken)
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