Regular Expressions with Ruby

What Do You Know? Sydney, 03 April, 2014

Transcript

1. Regular Expressions
   with Ruby
   Elle Meredith – @aemeredith
   

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2. Test
   Extract
   Change
   

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3. /fox/ =~ "The quick brown fox"
   Basic Matching
   

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4. /fox/ =~ "The quick brown fox"
   => 16
   Basic Matching
   

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5. /cat/ =~ "The quick brown fox"
   => nil
   Basic Matching
   

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6. /cat/ !~ "The quick brown fox"
   => true
   Basic Matching
   

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7. MatchData
   string = "The quick brown fox
   jumps over the lazy dog”
   

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8. MatchData
   string = "The quick brown fox
   jumps over the lazy dog”
   !
   matchdata = string.match /fox/
   => #
   

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9. MatchData
   matchdata.to_s
   => "fox"
   

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10. MatchData
    matchdata.pre_match
    => "The quick brown "
    

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11. MatchData
    matchdata.post_match
    => " jumps over the lazy dog"
    

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12. Captures
    string = "03APR2014"
    !
    string.match /\D{3}/
    

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13. Captures
    string = "03APR2014"
    !
    string.match /\D{3}/
    

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14. Captures
    string = "03APR2014"
    !
    string.match /\D{3}/
    

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15. Captures
    string = "03APR2014"
    !
    string.match /\D{3}/
    => #
    

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16. Captures
    md = string.match /(.*)(\D{3})(.*)/
    

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17. Captures
    md = string.match /(.*)(\D{3})(.*)/
    

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18. Captures
    md = string.match /(.*)(\D{3})(.*)/
    

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19. Captures
    md = string.match /(.*)(\D{3})(.*)/
    => #1:"03" 2:"APR" 3:"2014">
    

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20. Captures
    md.captures
    => ["03", "APR", "2014"]
    

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21. Captures
    md = string.match /(.*)(\D{3})(.*)/
    => #1:"03" 2:"APR" 3:"2014">
    

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22. Captures
    md[1]
    => "03"
    md[2]
    => "APR"
    md[3]
    => "2014"
    

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23. Named Captures
    md = string.match /(?.*)(?
    \D{3})(?.*)/
    => #day:"03" month:"APR"
    year:"2014">
    

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24. Named Captures
    md = string.match /(?.*)(?
    \D{3})(?.*)/
    => #day:"03" month:"APR"
    year:"2014">
    

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25. Named Captures
    md = string.match /(?.*)(?
    \D{3})(?.*)/
    => #day:"03" month:"APR"
    year:"2014">
    

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26. Named Captures
    md = string.match /(?.*)(?
    \D{3})(?.*)/
    => #day:"03" month:"APR"
    year:"2014">
    

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27. Named Captures
    md['day']
    => "03"
    

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28. Look Around
    string = '''
    I love my job, I love the pay!
    I love it more and more each day.
    I love my boss, he is the best!
    I love his boss and all the rest.
    '''
    

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29. Look Around
    string.scan /love my/
    => ["love my", "love my”]
    

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30. Positive Lookahead
    string.scan /love my (?=job)/
    => ["love my "]
    

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31. Changing things
    string.gsub(/love/, 'hate')
    

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32. Changing things
    string.gsub(/love/, 'hate')
    => "\nI hate my job, I hate the pay!
    \nI hate it more and more each
    day.\nI hate my boss, he is the
    best!\nI hate his boss and all the
    rest.\n"
    

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33. Changing things
    string.gsub!(/\she/, ' she').gsub!(/
    his/, 'her')
    

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34. Changing things
    string.gsub!(/\she/, ' she').gsub!(/
    his/, 'her')
    

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35. Changing things
    string.gsub!(/\she/, ' she').gsub!(/
    his/, ‘her')
    => "\nI love my job, I love the pay!
    \nI love it more and more each day.
    \nI love my boss, she is the best!\nI
    love her boss and all the rest.\n"
    

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37. Regular Expressions
    with Ruby
    Elle Meredith – @aemeredith
    

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