精通正则表达式（第三版）

5星 · 超过95%的资源需积分: 9 33 浏览量更新于2024-07-24 收藏 2.82MB PDF 举报

"Mastering Regular Expression 第三版" 《精通正则表达式》是 Jeffrey E.F. Friedl 的著作，这是一本深入探讨正则表达式的权威指南，已更新至第三版。这本书对于理解和掌握正则表达式的强大功能至关重要，无论你是初学者还是经验丰富的开发者，都能从中受益。正则表达式（Regular Expression）是一种用于处理字符串的强大工具，它在编程、文本处理、数据分析等领域广泛应用。本书深入浅出地讲解了正则表达式的语法、模式匹配、分组、反向引用、预查以及各种高级技巧。作者 Friedl 是正则表达式领域的专家，他的讲解不仅覆盖了基础概念，还涉及了许多实践中可能遇到的复杂情况。书中涵盖了以下关键知识点： 1. 基础语法：包括字符类、量词（如*、+、?）、锚点（^、$）、转义字符等，这些都是构建正则表达式的基础元素。 2. 模式匹配：如何使用正则表达式进行字符串匹配，包括单行模式、多行模式以及全局匹配。 3. 捕获与非捕获分组：通过 () 创建分组，可以捕获匹配的子串，同时学习如何创建非捕获分组以避免不必要的捕获。 4. 反向引用：使用 \数字引用之前捕获的分组，常用于重复或交替匹配。 5. 预查（Lookaround）：零宽度断言，包括前瞻和后顾，允许在不消耗字符的情况下检查上下文。 6. 条件表达式：根据之前的匹配结果来决定后续部分是否执行。 7. 正则表达式引擎：了解不同引擎（如 Perl、Java、JavaScript 等）的差异，以及如何优化正则表达式以适应特定环境。 8. 实践应用：包括在文本编辑器、命令行工具、Web 开发、搜索引擎优化等场景中的具体应用。此外，书中的实例丰富，涵盖了大量实际问题的解决方案，帮助读者将理论知识转化为实际操作能力。每一章结尾通常配有习题，鼓励读者动手实践，加深理解。《精通正则表达式》第三版在前两版的基础上进行了更新，加入了新的正则表达式特性，并对一些旧有内容进行了修订和完善，使其始终保持与时俱进。无论是对正则表达式感兴趣的初学者，还是希望提升自己在该领域技能的专业人士，这本书都是不可或缺的参考资料。

xx Preface

The introduction elevates the absolute novice to “issue-aware” novice. Readers

with a fair amount of experience can feel free to skim the early chapters, but I par-

ticularly recommend Chapter 3 even for the grizzled expert.

•Chapter 1, Intr oduction to Regular Expressions,isgear ed toward the complete

novice. I introduce the concept of regular expressions using the widely avail-

able program egr ep,and offer my perspective on how to think regular expres-

sions, instilling a solid foundation for the advanced concepts presented in later

chapters. Even readers with former experience would do well to skim this ﬁrst

chapter.

•Chapter 2, Extended Introductory Examples,looks at real text processing in a

pr ogramming language that has regular-expr ession support. The additional

examples provide a basis for the detailed discussions of later chapters, and

show additional important thought processes behind crafting advanced regular

expr essions. To provide a feel for how to “speak in regular expressions,”this

chapter takes a problem requiring an advanced solution and shows ways to

solve it using two unrelated regular-expr ession–wielding tools.

•Chapter 3, Overview of Regular Expression Features and Flavors,provides an

overview of the wide range of regular expressions commonly found in tools

today. Due to their turbulent history, current commonly-used regular-expr es-

sion ﬂavors can differ greatly. This chapter also takes a look at a bit of the his-

tory and evolution of regular expressions and the programs that use them. The

end of this chapter also contains the “Guide to the Advanced Chapters.”This

guide is your road map to getting the most out of the advanced material that

follows.

TheDetails

Once you have the basics down, it’s time to investigate the how and the why.Like

the “teach a man to ﬁsh” parable, truly understanding the issues will allow you to

apply that knowledge whenever and wherever regular expressions arefound.

•Chapter 4, The Mechanics of Expression Processing,ratchets up the pace sev-

eral notches and begins the central coreofthis book. It looks at the important

inner workings of how regular expression engines really work from a practi-

cal point of view. Understanding the details of how regular expressions are

handled goes a very long way toward allowing you to master them.

•Chapter 5, Practical Regex Techniques,then puts that knowledge to high-level,

practical use. Common (but complex) problems areexplor ed in detail, all with

the aim of expanding and deepening your regular-expr ession experience.

2July 2006 02:01

www.it-ebooks.info

•Chapter 6, Crafting an Efﬁcient Expression,looks at the real-life efﬁciency

ramiﬁcations of the regular expressions available to most programming lan-

guages. This chapter puts information detailed in Chapters 4 and 5 to use for

exploiting an engine’s strengths and stepping around its weaknesses.

Tool-Specific Infor mation

Once the lessons of Chapters 4, 5, and 6 areunder your belt, thereisusually little

to say about speciﬁc implementations. However,I’ve devoted an entirechapter to

each of four popular systems:

•Chapter 7, Perl,closely examines regular expressions in Perl, arguably the

most popular regular-expr ession–laden pr ogramming language in use today. It

has only four operators related to regular expressions, but their myriad of

options and special situations provides an extremely rich set of programming

options

—

and pitfalls. The very richness that allows the programmer to move

quickly from concept to program can be a mineﬁeld for the uninitiated. This

detailed chapter clears a path.

•Chapter 8, Java,looks in detail at the java.util.regex regular-expr ession

package, a standard part of the language since Java 1.4. The chapter’s primary

focus is on Java 1.5, but differ ences in both Java 1.4.2 and Java 1.6 arenoted.

•Chapter 9, .NET,isthe documentation for the .NET regular-expr ession library

that Microsoft neglected to provide. Whether using VB.NET,C#, C

,JScript,

VBscript, ECMAScript, or any of the other languages that use .NET components,

this chapter provides the details you need to employ .NET regular-expr essions

to the fullest.

•Chapter 10, PHP,provides a short introduction to the multiple regex engines

embedded within PHP,followed by a detailed look at the regex ﬂavor and API

of its preg regex suite, powered under the hood by the PCRE regex library.

Typog raphical Conventions

When doing (or talking about) detailed and complex text processing, being pre-

cise is important. The mereaddition or subtraction of a space can make a world of

dif ference, so I’ve used the following special conventions in typesetting this book:

• Aregular expression generally appears like

!this".Notice the thin corners

which ﬂag “this is a regular expression.”Literal text (such as that being

searched) generally appears like ‘this’. At times, I’ll leave offthe thin corners

or quotes when obviously unambiguous. Also, code snippets and screen shots

ar e always presented in their natural state, so the quotes and corners arenot

used in such cases.

Preface xxi

2July 2006 02:01

www.it-ebooks.info

xxii Preface

• Iuse visually distinct ellipses within literal text and regular expressions. For

example [˙˙˙] repr esents aset of squarebrackets with unspeciﬁed contents,

while [...] would be a set containing three periods.

• Without special presentation, it is virtually impossible to know how many

spaces arebetween the letters in “a b”,sowhen spaces appear in regular

expr essions and selected literal text, they arepresented with the ‘

’symbol.

This way, it will be clear that thereare exactly four spaces in ‘

b’.

• Ialso use visual tab, newline, and carriage-retur n characters:

aspace character

2 atab character

1 anewline character

| acarriage-r eturncharacter

• At times, I use underlining or shade the background to highlight parts of literal

text or a regular expression. In this example the underline shows whereinthe

text the expression actually matches:

Because

!cat" matches ‘It

indicat

your

cat

is˙˙˙’instead of the

word ‘

cat’, we realize . . .

In this example the underlines highlight what has just been added to an

expr ession under discussion:

To make this useful, we can wrap

!Subject;Date" with parentheses,

and append a colon and a space. This yields

Subject;Date):

• This book is full of details and examples, so I’ve included over 1,200 cross ref-

er ences to help you get the most out of it. They often appear in the text in a

“☞123” notation, which means “see page 123.”For example, it might appear

like “ ...isdescribed in Table 8-2 (

☞

367).”

Exer cises

Occasionally, and particularly in the early chapters, I’ll pose a question to highlight

the importance of the concept under discussion. They’renot therejust to take up

space; I really do want you to try them beforecontinuing. Please. So as not to

dilute their importance, I’ve sprinkled only a few throughout the entirebook. They

also serve as checkpoints: if they take morethan a few moments, it’s probably

best to go over the relevant section again beforecontinuing on.

To help entice you to actually think about these questions as you read them, I’ve

made checking the answers a breeze: just turnthe page. Answers to questions

marked with

❖

ar e always found by turning just one page. This way, they’reout

of sight while you think about the answer,but arewithin easy reach.

2July 2006 02:01

www.it-ebooks.info

xxiv Preface

Personal Comments and

Acknowledgments

Writing the ﬁrst edition of this book was a grueling task that took two and a half

years and the help of many people. After the toll it took on my health and sanity, I

pr omised that I’d never put myself through such an experience again.

Ihave many people to thank in helping me break that promise. Foremost is my

wife, Fumie. If you ﬁnd this book useful, thank her; without her support and

understanding, I’d have neither the strength nor sanity to undertake a task as ardu-

ous as the research, writing, and production of a book like this.

While researching and writing this book, many people helped educate me on lan-

guages or systems I didn’t know, and morestill reviewed and corrected drafts as

the manuscripts developed.

In particular,I’d like to thank my brother,Stephen Friedl, for his meticulous and

detailed reviews along the way. (Besides being an excellent technical reviewer,

he’s also an accomplished writer,known for his well-researched “Tech Tips,”avail-

able at http://www.unixwiz.net/)

I’d also like to thank Zak Greant, Ian Morse, Philip Hazel, Stuart Gill, William F.

Maton, and my editor,Andy Oram.

Special thanks for providing an insider’s look at Java go to Mike “madbot”

McCloskey (formerly at Sun Microsystems, now at Google), and Mark Reinhold

and Dr.Clif f Click, both of Sun Microsystems. For .NET insight, I’d like to thank

Micr osoft’s David Gutierrez, Kit George, and Ryan Byington. I thank Andrei

Zmievski of Yahoo! for providing insights into PHP.

I’d like to thank Dr.Ken Lunde of Adobe Systems, who created custom characters

and fonts for a number of the typographical aspects of this book. The Japanese

characters arefromAdobe Systems’ Heisei Mincho W3 typeface, while the Korean

is from the Korean Ministry of Cultureand Sports Munhwa typeface. It’s also Ken

who originally gave me the guiding principle that governs my writing: “you do the

research so your readers don’t have to.”

For help in setting up the server for http://r egex.info,I’d like to thank Jeffr ey

Papen and Peak Web Hosting (http://www.PeakWebhosting.com/).

2July 2006 02:01

www.it-ebooks.info

剩余533页未读，继续阅读

aixufeng

粉丝: 1
资源: 4

精通正则表达式（第三版）

MasteringRegularExpressions3rdEdition.pdf 英文原版

中文版Mastering Regular Expressions（第三版）

Mastering Regular Expressions(3rd) 无水印pdf

Mastering Regular Expressions

正则表达式 Mastering Regular Expressions

Mastering Regular Expressions.pdf

Mastering Regular Expressions, 2nd Edition

Mastering Regular Expressions, 3rd Edition

正则表达式权威指南：Mastering Regular Expressions

Mastering Regular Expressions - 英文版技术参考

最新资源