Introducing Regular Expressions

by Fitzgerald, Michael

• ISBN13: 9781449392680
• ISBN10: 1449392687
• Edition: 1st
• Format: Paperback
• Copyright: 2012-07-31
• Publisher: Oreilly & Associates Inc

Summary

Regular expressions remain a difficult part of the puzzle when learning how to program. Commonly used for sifting through large chunks of text, regexes are incredibly powerful although they may appear daunting to the newcomer. And variations among languages and environments make them even harder to master. Loaded with examples, this introductory guide walks beginners step-by-step through the fundamentals of regular expressions, and helps you decipher complex patterns. Break down regular expressions into comprehensible parts Learn common usage patterns through simple, easy-to-follow examples Discover how finding unique patterns can help you avoid repetitive, hand-editing of text Use common command-line tools such as grep and sed Compare how regular expressions are implemented in different languages and environments

Author Biography

Michael Fitzgerald, a programmer and consultant, has written several technical books for O'Reilly and John Wiley Sons, as well as several articles for the O'Reilly Network. He was a member of the original committee that created the RELAX NG schema language for XML.

Table of Contents

Preface	p. vii
What Is a Regular Expression?	p. 1
Getting Started with Regexpal	p. 2
Matching a North American Phone Number	p. 2
Matching Digits with a Character Class	p. 4
Using a Character Shorthand	p. 5
Matching Any Character	p. 5
Capturing Groups and Back References	p. 6
Using Quantifiers	p. 6
Quoting Literals	p. 8
A Sample of Applications	p. 9
What You Learned in Chapter 1	p. 11
Technical Notes	p. 11
Simple Pattern Matching	p. 13
Matching String Literals	p. 15
Matching Digits	p. 15
Matching Non-Digits	p. 17
Matching Word and Non-Word Characters	p. 18
Matching Whitespace	p. 20
Matching Any Character, Once Again	p. 22
Marking Up the Text	p. 24
Using sed to Mark Up Text	p. 24
Using Perl to Mark Up Text	p. 25
What You Learned in Chapter 2	p. 27
Technical Notes	p. 27
Boundaries	p. 29
The Beginning and End of a Line	p. 29
Word and Non-word Boundaries	p. 31
Other Anchors	p. 33
Quoting a Group of Characters as Literals	p. 34
Adding Tags	p. 34
Adding Tags with sed	p. 36
Adding Tags with Perl	p. 37
What You Learned in Chapter 3	p. 38
Technical Notes	p. 38
Alternation, Groups, and Backreferences	p. 41
Alternation	p. 41
Subpatterns	p. 45
Capturing Groups and Backreferences	p. 46
Named Groups	p. 48
Non-Capturing Groups	p. 49
Atomic Groups	p. 50
What You Learned in Chapter 4	p. 50
Technical Notes	p. 51
Character Classes	p. 53
Negated Character Classes	p. 55
Union and Difference	p. 56
POSIX Character Classes	p. 56
What You Learned in Chapter 5	p. 59
Technical Notes	p. 60
Matching Unicode and Other Characters	p. 61
Matching a Unicode Character	p. 62
Using vim	p. 63
Matching Characters with Octal Numbers	p. 64
Matching Unicode Character Properties	p. 65
Matching Control Characters	p. 68
What You Learned in Chapter 6	p. 70
Technical Notes	p. 71
Quantifiers	p. 73
Greedy, Lazy, and Possessive	p. 74
Matching with *, +, and ?	p. 74
Matching a Specific Number of Times	p. 75
Lazy Quantifiers	p. 76
Possessive Quantifiers	p. 77
What You Learned in Chapter 7	p. 78
Technical Notes	p. 79
Lookarounds	p. 81
Positive Lookaheads	p. 81
Negative Lookaheads	p. 84
Positive Lookbehinds	p. 85
Negative Lookbehinds	p. 85
What You Learned in Chapter 8	p. 86
Technical Notes	p. 86
Marking Up a Document with HTML	p. 87
Matching Tags	p. 87
Transforming Plain Text with sed	p. 88
Substitution with sed	p. 89
Handling Roman Numerals with sed	p. 90
Handling a Specific Paragraph with sed	p. 91
Handling the Lines of the Poem with sed	p. 91
Appending Tags	p. 92
Using a Command File with sed	p. 92
Transforming Plain Text with Perl	p. 94
Handling Roman Numerals with Perl	p. 95
Handling a Specific Paragraph with Perl	p. 96
Handling the Lines of the Poem with Perl	p. 96
Using a File of Commands with Perl	p. 97
What You Learned in Chapter 9	p. 98
Technical Notes	p. 98
The End of the Beginning	p. 101
Learning More	p. 102
Notable Tools, Implementations, and Libraries	p. 103
Perl	p. 103
PCRE	p. 103
Ruby (Oniguruma)	p. 104
Python	p. 104
RE2	p. 105
Matching a North American Phone Number	p. 105
Matching an Email Address	p. 105
What You Learned in Chapter 10	p. 106
Appendix: Regular Expression Reference	p. 107
Regular Expression Glossary	p. 123
Index	p. 129
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