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Pattern matching - FAST code
Pattern matching example from a Well House Consultants training course
More on Pattern matching [link]

This example is described in the following article(s):
   • Making a Lua program run more than 10 times faster - [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)
                running = false
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
Yes. We have over 700 books in our library. Books covering Lua are listed here and when you've selected a relevant book we'll link you on to Amazon to order.

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
You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources
• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre.
The Horse's mouth provides a daily tip or thought.
• Further resources are available via the resources centre.
• All of these resources can be searched through through our search engine
• And there's a global index here.

Purpose of this website
This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.

Web site author
This web site is written and maintained by Well House Consultants.

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Past attendees on our training courses are welcome to use individual examples in the course of their programming, but must check the examples they use to ensure that they are suitable for their job. Remember that some of our examples show you how not to do things - check in your notes. Well House Consultants take no responsibility for the suitability of these example programs to customer's needs.

This program is copyright Well House Consultants Ltd. You are forbidden from using it for running your own training courses without our prior written permission. See our page on courseware provision for more details.

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