Regular expressions basics/正規表現の基本

Regular expressions basics/正規表現の基本

Transcript

1. ਖ਼نදݱͷجຊ
   Regular expressions basics
   

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2. Swift Regex
   

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3. https://swiftregex.com/
   

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4. ਖ਼نදݱͱ͸
   • จࣈྻͷू߹ʢύλʔϯʣΛද͢൚༻తͳه๏
   
   • [bc]ook͸book·ͨ͸cookʹϚον͢Δ
   

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5. Ϧςϥϧ
   Literal Characters
   • a
   
   • Jack is a boy,
   
   • cat
   
   • About cats and dogs
   

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6. ϝλจࣈ
   Special Characters (Meta Characters)
   • ಛผͳҙຯΛ࣋ͭ12ͷจࣈʢϦςϥϧͱͯ͠ѻ͏ʹ͸Τεέʔϓ͕ඞཁɻʢྫʣ1\+1=2ʣ
   
   • όοΫεϥογϡ \
   
   • ΩϟϨοτ ^
   
   • υϧϚʔΫ $
   
   • υοτʢϐϦΦυʣ .
   
   • ύΠϓ |
   
   • ΫΤενϣϯϚʔΫ ?
   
   • ΞελϦεΫ *
   
   • ϓϥε +
   
   • ։ؙ͖Χοί (
   
   • ดؙ͡Χοί )
   
   • ։͖֯Χοί [
   
   • ։͖೾Χοί {
   

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7. ੍ޚจࣈ
   Non-Printable Characters (Control Characters, Escape sequence)
   • \t
   
   • λϒʹϚον͢Δ
   
   • \n
   
   • վߦʹϚον͢Δ
   

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8. จࣈΫϥε
   Character Classes (Character Sets)
   • ෳ਺ͷจࣈͷத͔Β̍ͭͷจࣈʹϚον͢Δ
   
   • a·ͨ͸eʹϚονͤ͞Δʹ͸[ae]ͱॻ͘
   
   • ʢྫʣgr[ae]y
   
   • gray·ͨ͸greyʹϚον
   
   • จࣈΫϥε͸1ͭͷจࣈʹϚον͢Δ
   
   • Χοίͷதͷจࣈͷॱং͸ؔ܎ͳ͍
   

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9. จࣈΫϥε
   Character Classes (Character Sets)
   • จࣈΫϥεͷதͰϋΠϑϯΛ࢖༻ͯ͠ൣғΛࢦఆͰ͖Δ
   
   • [0-9]
   
   • ͔̌Β̕ͷؒͷܻ̍ͷ਺ࣈʹϚον
   
   • [0-9a-fA-F]
   
   • େจࣈͱখจࣈΛ۠ผͤͣʹɺ16ਐ਺ͷ਺ࣈܻ̍ʹϚον
   
   • ൱ఆจࣈΫϥεʢNegated Character Classesʣ
   
   • [^0-9\r\n]
   
   • ਺ࣈ·ͨ͸վߦͰͳ͍೚ҙͷจࣈʹϚον
   

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10. จࣈΫϥεʢͷུه๏ʣ
    Shorthand Character Classes
    • จࣈΫϥεͷதͰΑ͘࢖ΘΕΔ΋ͷΛ؆୯ʹॻ͚ΔΑ͏ʹ͋Β͔͡Ί༻ҙ͞Εͨه๏
    
    • \d͸[0-9]ͷུه๏
    
    • UnicodeΛαϙʔτ͢Δ؀ڥͰ͸׽਺ࣈ΍ؙ਺ࣈͳͲ͢΂ͯͷ਺ࣈʹϚον
    • \w “word character” [A-Za-z0-9_]ͱಉ͡ʢΞϯμʔείΞؚ͕·ΕΔ͜ͱʹ஫ҙʣ
    
    • UnicodeΛαϙʔτ͢Δ؀ڥͰ͸͍Ζ͍ΖͳจࣈʹϚον
    • \s “whitespace character” ۭനจࣈʹϚον [ \t\r\n\f]
    
    • UnicodeΛαϙʔτ͢Δ؀ڥͰ͸UnicodeͷʮseparatorʯΧςΰϦͷ͢΂ͯͷจࣈʹϚον
    

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11. υοτʢϐϦΦυʣ
    The Dot Matches (Almost) Any Character
    • վߦจࣈΛআ̍͘จࣈʹϚον
    
    • “dot matches all”·ͨ͸“single line”Ϟʔυʢϓϩάϥϛϯάݴޠ΍ਖ਼نදݱΤ
    ϯδϯʹΑͬͯݺͼํ͸ҟͳΔʣΛࢦఆ͢ΔͱվߦจࣈΛؚΉ೚ҙͷ1จࣈʹ
    Ϛον
    
    • gr.y͸ɺgrayɺgrayɺgr%yͳͲʹϚον
    
    • υοτ͸ڧྗʹͳΜͰ΋Ϛον͢ΔͷͰ࢖͍͗͢ͳ͍
    
    • จࣈΫϥε΍൱ఆจࣈΫϥεΛ୅ΘΓʹ࢖͏
    

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12. ΞϯΧʔ
    Anchors
    • จࣈͰ͸ͳ͘ҐஔʹϚον
    
    • ^
    
    • จࣈྻͷઌ಄ʹϚον
    
    • $
    
    • จࣈྻͷ຤ඌʹϚον
    
    • ΄ͱΜͲͷਖ਼نදݱ͸“multi-line”Ϟʔυ͕͋Γɺ ^͸վߦͷޙΖɺ $͸վߦͷલʹϚον͢Δ
    
    • \b
    
    • ୯ޠڥքʹϚον
    
    • ୯ޠڥքͱ͸\wͰϚονͰ͖ΔจࣈͱɺͰ͖ͳ͍จࣈͷؒͷҐஔ
    

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13. બ୒
    Alternation
    • ࿦ཧ࿨ʢORʣ
    
    • cat|dog
    
    • About cats and dogs
    
    • cat|dog|mouse|
    fi
    sh
    
    • ޷͖ͳ͚ͩͭͳ͛Δ͜ͱ͕Ͱ͖Δ
    
    • cat|dog food
    
    • cat·ͨ͸dog foodʹϚον
    
    • cat food͔dog foodʹϚονͤ͞Δʹ͸ɺ(cat|dog) foodͷΑ͏ʹબ୒ΛάϧʔϓԽ͢Δ
    

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14. ܁Γฦ͠
    Repetition
    • ΫΤενϣϯϚʔΫʮ?ʯ
    
    • Optional
    
    • colou?r͸color·ͨ͸colourʹϚον
    
    • ΞελϦεΫʮ*ʯ
    
    • ̌ճҎ্ͷ܁Γฦ͠
    
    •
    
    • ଐੑ͕ͳ͍HTMLλάʹϚον
    
    • ϓϥεʮ+ʯ
    
    • ̍ճҎ্ͷ܁Γฦ͠
    
    • ೾Χοίʮ{n,m}ʯ
    
    • ࢦఆճ਺ͷ܁Γฦ͠
    
    • \b[1-9][0-9]{3}b
    
    • 1000͔Β9999ͷ਺ࣈʹϚον
    
    • \b[1-9][0-9]{2,4}\b
    
    • 100͔Β99999ͷ਺ࣈʹϚον
    

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15. άϧʔϓͱΩϟϓνϟ
    Grouping and Capturing
    • ΧοίͰғΉͱάϧʔϓԽ͞ΕΔ
    
    • άϧʔϓʹରͯ͠܁Γฦ͠ΛࢦఆͰ͖Δ
    
    • Set(Value)?
    
    • Set·ͨ͸SetValueʹϚον
    
    • ௨ৗͷؙΧοί͸ΩϟϓνϟάϧʔϓΛ࡞੒͢Δ
    
    • Set(Value)?ͷਖ਼نදݱͰSetValue͕Ϛονͨ͠৔߹͸ɺάϧʔϓ̍ʹΞΫηε͢ΔͱValue͕औΓग़ͤΔ
    
    • Ωϟϓνϟ͕ඞཁͳ͍৔߹͸Set(?:Value)?ͱ͢ΔͱΩϟϓνϟ͠ͳ͍άϧʔϓ͕࡞੒Ͱ͖Δ
    
    • ؙΧοίͷޙͷΫΤενϣϯϚʔΫͱɺ̌ճҎ্ͷ܁Γฦ͠ͷࢦఆͷΫΤενϣϯϚʔΫΛࠞಉ͠ͳ͍Α͏ʹ
    ஫ҙ
    

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16. ޙํࢀর
    Backreferences
    • ΩϟϓνϟάϧʔϓͰΩϟϓνϟʢϚονʣͨ͠಺༰ʹϚον
    
    • ΩϟϓνϟάϧʔϓʹϚονͨ݁͠ՌΛ࠶ར༻Ͱ͖Δ
    
    • ]*>.*?\1>
    
    • HTMLλάʹϚονʢΩϟϓνϟάϧʔϓʹϚονͨ͠։࢝λάΛऴྃλάͰ
    ࠶ར༻͍ͯ͠Δʣ
    

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17. ໊લ෇͖άϧʔϓʢΩϟϓνϟʣͱޙํࢀর
    Named Groups and Backreferences
    • Ωϟϓνϟ΁ͷࢀরΛ൪߸Ͱ؅ཧ͢Δͷ͸େมͩ͠ɺ௥Ճ࡟আͰͣΕΔͷͰ໊લΛ෇͚ΒΕΔ
    
    • ߏจʢ໊લ෇͖άϧʔϓʣ
    
    • (?Pgroup)
    
    • ߏจʢޙํࢀরʣ
    
    • (?P=name)
    
    • [A-Z][A-Z0-9]*)\b[^>]*>.*?(?P=tag)>
    
    • HTMLλάʹϚονʢ ]*>.*?\1>ͱಉ͡ʣ
    
    • ߏจʢ໊લ෇͖Ωϟϓνϟʢ.NETʣʣ
    
    • (?group)·ͨ͸(?’name'group)
    
    • ߏจʢ໊લʹΑΔࢀরʢ.NETʣʣ
    
    • \k·ͨ͸\k'name'
    

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18. ઌಡΈͱޙಡΈ
    Lookaround (Lookahead/Lookback(Lookbehind))
    • ಛघͳάϧʔϓͰɺΞϯΧʔͷΑ͏ʹϚονͨ݁͠ՌͷҐஔΛࢦఆ͢Δ
    
    • ʢྫʣ\d+(?=€)
    
    • ੔਺஋ͷޙʹʮ€ʯ͕ଓ͘จࣈྻʹϚον
    
    • 1 turkey costs 30€ͷ30ʹϚον
    
    • ߏจʢߠఆઌಡΈʢPositive lookaheadʣʣ
    
    • X(?=Y)
    
    • ߏจʢ൱ఆઌಡΈʢNegative lookaheadʣʣ
    
    • X(?!Y)
    
    • ߏจʢߠఆޙಡΈʢPositive lookbehindʣʣ
    
    • (?<=Y)X
    
    • ߏจʢ൱ఆޙಡΈʢNegative lookbehindʣʣ
    
    • (?

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19. References
    • Regular-Expressions.info

    https://www.regular-expressions.info/
    
    • Swift Regex

    https://swiftregex.com/
    

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