Mastering Regular Expressions, Third Edition

Regular expressions are an extremely powerful tool for manipulating text and data. They are now standard features in a wide range of languages and popular tools, including Perl, Python, Ruby, Java, VB.NET and C# (and any language using the .NET Framework), PHP, and MySQL. If you don't use regular expressions yet, you will discover in this book a whole new world of mastery over your data. If you already use them, you'll appreciate this book's unprecedented detail and breadth of coverage. If you think you know all you need to know about regular expressions, this book is a stunning eye-opener. As this book shows, a command of regular expressions is an invaluable skill. Regular expressions allow you to code complex and subtle text processing that you never imagined could be automated. Regular expressions can save you time and aggravation. They can be used to craft elegant solutions to a wide range of problems. Once you've mastered regular expressions, they'll become an invaluable part of your toolkit. You will wonder how you ever got by without them. Yet despite their wide availability, flexibility, and unparalleled power, regular expressions are frequently underutilized. Yet what is power in the hands of an expert can be fraught with peril for the unwary. Mastering Regular Expressions will help you navigate the minefield to becoming an expert and help you optimize your use of regular expressions. Mastering Regular Expressions, Third Edition, now includes a full chapter devoted to PHP and its powerful and expressive suite of regular expression functions, in addition to enhanced PHP coverage in the central "core" chapters. Furthermore, this edition has been updated throughout to reflect advances in other languages, including expanded in-depth coverage of Sun's java.util.regex package, which has emerged as the standard Java regex implementation.Topics include: A comparison of features among different versions of many languages and tools How the regular expression engine works Optimization (major savings available here!) Matching just what you want, but not what you don't want Sections and chapters on individual languages Written in the lucid, entertaining tone that makes a complex, dry topic become crystal-clear to programmers, and sprinkled with solutions to complex real-world problems, Mastering Regular Expressions, Third Edition offers a wealth information that you can put to immediate use. Reviews of this new edition and the second edition: "There isn't a better (or more useful) book available on regular expressions." --Zak Greant, Managing Director, eZ Systems "A real tour-de-force of a book which not only covers the mechanics of regexes in extraordinary detail but also talks about efficiency and the use of regexes in Perl, Java, and .NET...If you use regular expressions as part of your professional work (even if you already have a good book on whatever language you're programming in) I would strongly recommend this book to you." --Dr. Chris Brown, Linux Format "The author does an outstanding job leading the reader from regex novice to master. The book is extremely easy to read and chock full of useful and relevant examples...Regular expressions are valuable tools that every developer should have in their toolbox. Mastering Regular Expressions is the definitive guide to the subject, and an outstanding resource that belongs on every programmer's bookshelf. Ten out of Ten Horseshoes." --Jason Menard, Java Ranch Cover......Page 1 Title page......Page 3 Copyright page......Page 4 Dedication......Page 5 Table of Contents......Page 7 The Need for This Book......Page 17 Intended Audience......Page 18 Organization......Page 19 The Details......Page 20 Typographical Conventions......Page 21 Exercises......Page 22 Safari®Enabled......Page 23 Personal Comments and Acknowledgments......Page 24 1 Introduction to Regular Expressions......Page 25 Solving Real Problems......Page 26 The Filename Analogy......Page 28 The Language Analogy......Page 29 Searching Text Files: Egrep......Page 30 Start and End of the Line......Page 32 Matching any one of several characters......Page 33 Negated character classes......Page 34 Matching Any Character with Dot......Page 35 Matching any one of several subexpressions......Page 37 Ignoring Differences in Capitalization......Page 38 Word Boundaries......Page 39 In a Nutshell......Page 40 Optional Items......Page 41 Other Quantifiers: Repetition......Page 42 Parentheses and Backreferences......Page 44 The Great Escape......Page 46 A Few More Examples......Page 47 Dollar amount (with optional cents)......Page 48 An HTTP/HTML URL......Page 49 Time of day, such as "9:17 am" or "12:30 pm"......Page 50 Flavor......Page 51 Extending the Time Regex to Handle a 24–Hour Clock......Page 52 Character......Page 53 Improving on the Status Quo......Page 54 Summary......Page 56 Personal Glimpses......Page 57 2 Extended Introductory Examples......Page 59 About the Examples......Page 60 A Short Introduction to Perl......Page 61 Matching Text with Regular Expressions......Page 62 Side Effects of a Successful Match......Page 64 Intertwined Regular Expressions......Page 67 A short aside—metacharacters galore......Page 68 Non-Capturing Parentheses: (?:•••)......Page 69 Generic "whitespace" with ......Page 71 Intermission......Page 73 Example: Form Letter......Page 74 Example: Prettifying a Stock Price......Page 75 A Small Mail Utility......Page 77 A Sample Email Message......Page 78 A Warning About .*......Page 80 Real-world problems, real-world solutions......Page 82 Adding Commas to a Number with Lookaround......Page 83 Lookaround doesn't "consume" text......Page 84 A few more lookahead examples......Page 85 Back to the comma example.........Page 88 Word boundaries and negative lookaround......Page 89 Text-to-HTML Conversion......Page 91 Cooking special characters......Page 92 Separating paragraphs......Page 93 "Linkizing" an email address......Page 94 Matching the username and hostname......Page 95 Putting it together......Page 97 "Linkizing" an HTTP URL......Page 98 Building a regex library......Page 100 That Doubled-Word Thing......Page 101 Moving bits around: operators, functions, and objects......Page 104 Regular Expressions and Cars......Page 107 In This Chapter......Page 108 The Origins of Regular Expressions......Page 109 Egrep evolves......Page 110 POSIX—An attempt at standardization......Page 111 Perl evolves......Page 112 A partial consolidation of flavors......Page 114 At a Glance......Page 115 Care and Handling of Regular Expressions......Page 117 Integrated Handling......Page 118 A procedural example......Page 119 Regex handling in VB and other .NET languages......Page 120 Why do approaches differ?......Page 121 Search and replace in Java......Page 122 Search and replace in PHP......Page 123 GNU Emacs......Page 124 Strings as Regular Expressions......Page 125 Strings in Java......Page 126 Strings in PHP......Page 127 Strings in Tcl......Page 128 Character-Encoding Issues......Page 129 Unicode......Page 130 Characters versus combining-character sequences......Page 131 Multiple code points for the same character......Page 132 Unicode line terminator......Page 133 Case-insensitive match mode......Page 134 Dot-matches-all match mode (a.k.a., "single-line mode")......Page 135 Enhanced line-anchor match mode (a.k.a., "multiline mode")......Page 136 Common Metacharacters and Features......Page 137 These are machine dependent?......Page 139 Octal escape—\num......Page 140 Control characters: \ cchar......Page 141 Normal classes: [a-z] and [^a-z]......Page 142 Dot versus a negated character class......Page 143 Class shorthands: \w, \d, , \W, \D, \S......Page 144 Unicode properties, scripts, and blocks: \p{Prop}, \P{Prop}......Page 145 Scripts......Page 146 Other properties/qualities......Page 148 Full class set operations: [[a-z] && [^aeiou]]......Page 149 Mimicking class set operations with lookaround......Page 150 POSIX bracket-expression "character class": [[:alpha:]]......Page 151 Emacs syntax classes......Page 152 End of line/string: $, \Z, \z......Page 153 Start of match (or end of previous match): \G......Page 154 End of previous match, or start of the current match?......Page 155 Advanced Use of \G with Perl......Page 156 Lookahead (?=•••), (?!•••); Lookbehind, (?