Mastering Regular Expressions - Table of Contents

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happens is different for most tools. awk, lex, and egrep are among the few tools
for which it would actually be identical this is the topic of Chapter 4. Even if it
were exactly the same, it could be useful for its notational convenience or clarity.
As Larry Wall explained to me once, "It's like having a zero in your numbering
system."
Guide to the Advanced Chapters
Now that we're familiar with metacharacters, flavors, syntactic packaging, and the
like, it's time to start getting into the nitty-gritty details, the meat of the subject,
the "hard core," if you will. This begins in Chapter 4, The Mechanics of
Expression Processing. There are different ways a tool's match engine might be
implemented, and the selection influences if a match is achieved or not, which text
in the string gets matched, and how much time the whole thing takes. We'll look at
all the details. As a byproduct of this knowledge, it will become much easier for
you to craft complex expressions with confidence.
This brings us to Chapter 5, Crafting a Regular Expression. Once you know the
basics about how an engine works, you can consider techniques to take full
advantage of that knowledge and of the engine. Chapter 5 looks at some of the
pitfalls of certain popular regex flavors pitfalls that often lead to unwelcome
surprises and turns the tables to put them to use for us.
Chapters 4 and 5 are the central core of this book, its essence. These first three
chapters merely lead up to them, and the discussions in the tool-specific chapters
that follow rely on them. It's not necessarily what you would call light reading,
but I've taken great care to stay away from math and algebra and all that stuff
that's just mumbo-jumbo to most of us. As with any large amount of new
information, it will likely take time to sink in and internalize.
Tool-Specific Information
The lessons and techniques discussed in Chapters 4 and 5 transcend any particular
tool. You might need to cosmetically adjust the examples to fit a certain flavor,
but it's the lessons that are important, not the examples.