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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 print (count,mcount,ip,query) end end else running = false end end taken = os.clock() print ("time taken in seconds - ",taken) Learn about this subject
This module and example are covered on the following public courses:
* Learning to program in Lua * Lua Programming * Lua Programming Also available on on site courses for larger groups Books covering this topic
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Other Examples
This example comes from our "Pattern matching" training module. You'll find a description of the topic and some
other closely related examples on the "Pattern matching" module index page.
Full description of the source code
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