Mastering Regular Expressions [Paperback]

Jeffrey E.F. Friedl (Author)

Book Description

Publication Date: January 15, 1997 | Series: Nutshell Handbooks

Regular expressions are a powerful tool for manipulating text and data. If you don't use them 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.

With regular expressions, you can save yourself time and aggravation while dealing with documents, mail messages, log files -- you name it -- any type of text or data. For example, regular expressions can play a vital role in constructing a World Wide Web CGI script, which can involve text and data of all sorts.

Regular expressions are not a tool in and of themselves, but are included as part of a larger utility. The classic example is grep. These days, regular expressions can be found everywhere, such as in:

• Scripting languages (including Perl, Tcl, awk, and Python)
• Editors (including Emacs, vi, and Nisus Writer)
• Programming environments (including Delphi and Visual C++)

While many of these tools originated on UNIX, they are now available for a wide variety of platforms, including DOS/Windows and MacOS, so you can use them in your home environment. Additionally, many favorite programming languages offer regular-expression libraries, so you can include support for them in your own programs, and yes, even applets.

There can be certain subtle, but valuable, ways to think when you're using regular expressions, and these can be taught. Jeffrey Friedl has spent years helping people on the Net understand and use regular expressions. In this book he leads you through the steps of knowing exactly how to craft a regular expression to get the job done.

Regular expressions are not used in a vacuum. In this book, a variety of tools are examined and used in an extensive array of examples, with a major focus on Perl. Perl is extremely well endowed with rich and expressive regular expressions. Yet what is power in the hands of an expert can be fraught with peril for the unwary. This book will help you navigate the minefield to becoming an expert.

Editorial Reviews

Amazon.com Review

Regular expressions are a central element of UNIX utilities like egrep and programming languages such as Perl. But whether you're a UNIX user or not, you can benefit from a better understanding of regular expressions since they work with applications ranging from validating data-entry fields to manipulating information in multimegabyte text files. Mastering Regular Expressions quickly covers the basics of regular-expression syntax, then delves into the mechanics of expression-processing, common pitfalls, performance issues, and implementation-specific differences. Written in an engaging style and sprinkled with solutions to complex real-world problems, Mastering Regular Expressions offers a wealth information that you can put to immediate use.

Review

"Indispensable for text processing wizards and regex newcomers alike." - Paul Hudson, Linux Format, February 2007 "In addition to the sheer volume of information, one thing that sets this book apart is that the author uses "real-world" rather than contrived examples. A few of the examples were situations that I have yet to come across, but many were either "been there, done that" or things that I had to go out and try." - James Mohr, Linux Magazine, April 2007 --This text refers to an alternate Paperback edition.

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Product Details

• Paperback: 342 pages
• Publisher: O'Reilly Media; 1st ed edition (January 15, 1997)
• Language: English
• ISBN-10: 1565922573
• ISBN-13: 978-1565922570
• Product Dimensions: 9.1 x 7 x 1 inches
• Shipping Weight: 1.2 pounds
• Average Customer Review: 4.5 out of 5 stars  See all reviews (146 customer reviews)
• Amazon Best Sellers Rank: #511,651 in Books (See Top 100 in Books)

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Customer Reviews

Most Helpful Customer Reviews

123 of 132 people found the following review helpful:

5.0 out of 5 stars I need more stars... Bravo Jeffrey, December 8, 2001

By 

"sherzodr" - See all my reviews

This review is from: Mastering Regular Expressions (Paperback)

Jeffrey Friedl's "Matering Regular Expressions" does a facinating job in taking you through the jungle (and I mean jungle) of RegExp.

I am a Perl/CGI programmer, and I had considered myself good at RegExp even before I read this book. Most of the things I knew were from Programming Perl, 3rd edition (chapter 5, Pattern Matching). But I still decided to give Jeffrey a chance since I was having some trouble with my Parse::Syntax module, which is designed to parsing *any* programming language and highlighting the syntax accordingly (provided it has a syntax/grammer file written for the specific language). The accuracy of the parser (and more importantly the speed) does depend on well crafted regular expressions.

As I started reading the book, I couldn't stop. I took it to my school's cafeteria with me and no one could make me leave untill I finished the whole book. I was excited. I was pleased! Here is the outline of tha chapters:

Chapter 1 and 2 introduce you to regular expressions and give some basic regex examples. Mail utility and date matching is two of them.

Chapter 3 mostly talks about conventions that all the regex tools follow and their differences.

Chapter 4 deals with Traditional NFA, POSIX NFA and DFA regex engines and their pros and cons. What you'll like the most is the details provided by the author on each and every single example. He also uses a lot of step-by-step illustrations to take you deeper into the regex engine itself and see/feel how it works. He shows the point of backtrackings and provides awesome benchmarks. He uses such examples of matching a quote, allowing escaped quotes inside the pattern, matching C-style comments, IP addresses and many more.

Chapter 5 deals with writing efficient regular expressions for NFA engines. It also re-vists some of the examples provided in the previous chapter and fine-tunes them.

Chapter 6 and 7 deals with Tool-Language specific features of Regex engines. Chapter 6 is dedicated to Awk, Tcl and GNU Emacs, whereas chapter 7 is entirely dedicated to Perl, good over 100 pages of Perlism.

It's true that there're features that Perl 5.6 offers when it comes to regex that didn't exist at the time this book went to press, (lookbehinds, for example). But this no way makes this book dated. Just take my word for it. Jeffrey put together a great masterpiece that will not die for many years, no matter how fast the technology tends to enhance
Haven't read anything more exciting than this for many years.

38 of 39 people found the following review helpful:

5.0 out of 5 stars Those wise birds!, May 3, 2001

By 

Alfred Anzlovar - See all my reviews

This review is from: Mastering Regular Expressions (Paperback)

I got Mastering Regular Expressions in 1998 and I peek back regularly and it am proud to say is one of most used and useful books I own.

Regular expressions are for everyone. They are simple to write and can be close to impossible to read and even unimaginably harder to understand. But reading comes after you can craft one.

And this art of crafting RE is explained in astonishing detail and analysis in this book. Reader is carefully guided through basics, differences and common and uncommon pitfalls. Some of the parts are definitely not for the faint hearted! And this is especially true for parts that cover Perl RE. While main topic is Perl RE engine, a deep-enough travel through different RE dialects is made to help RE-crafting in almost any tool that supports REs.

I've used the methods described in the book in tools as different as MS VC++, various editors, search engines and programming (Perl, PHP, C++, ...). The ability to use RE usually impressed people to the point they were sure I am using some incredible magic.

But I must say that the most useful feature delivered in this book was ability to PARSE, UNDERSTAND and FIX a (slow, broken, strange acting) RE. This can be slowly absorbed by reader's (open) mind while carefully reading the book. The difference between meant/written can be as extreme as it can get in RE. I can (proudly) say I've been able to fix several complex REs, by simply (one could say blindly) following the rules laid in the book.

My opinion is thath without this book real understanding of RE is almost impossible. I recommended it all of those who use programs that support (any form) of RE engine. It will help them solve some (hard) problems incredibly fast!

17 of 17 people found the following review helpful:

5.0 out of 5 stars So good, I bought it twice!, January 5, 2003

By 

Bob Nelson (Frisco, TX United States) - See all my reviews
(REAL NAME)   

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This review is from: Mastering Regular Expressions, Second Edition (Paperback)

In spite of the vow that Friedl would not put himself (and his family) through the rigors of writing a followup to his first edition, I sure am glad he made the decision to write a second edition. Over 5 years ago, I got the first such book and found it to be a humbling experience -- realizing just how little I *really* knew about regular expressions (in spite of thinking my skills were quite advanced in that area).

Now, years later and as an instructor of UNIX at North Lake College in Irving, Texas, I highly recommend this book to even our first year students. Friedl's clear explanation of this topic and the manner in which he presents the material makes it comprehensible to even those that have never had experience with regex's before. Like Perl's Larry Wall, Jeffrey Friedl has a strong background in natural languages. That contributes not only to bhis lucid writing style but also helps in terms of understanding regex's as a "little language".

This 2nd edition is particularly welcome because of its extensive coverage of regular expressions in the context of Java. That ons aspect alone is sufficient to get the updated second edition (to say nothing of the enhancements in Perl since the first edition of the book).