- •Introduction
- •Who This Book Is For
- •What This Book Covers
- •How This Book Is Structured
- •What You Need to Use This Book
- •Conventions
- •Source Code
- •Errata
- •p2p.wrox.com
- •What Are Regular Expressions?
- •What Can Regular Expressions Be Used For?
- •Finding Doubled Words
- •Checking Input from Web Forms
- •Changing Date Formats
- •Finding Incorrect Case
- •Adding Links to URLs
- •Regular Expressions You Already Use
- •Search and Replace in Word Processors
- •Directory Listings
- •Online Searching
- •Why Regular Expressions Seem Intimidating
- •Compact, Cryptic Syntax
- •Whitespace Can Significantly Alter the Meaning
- •No Standards Body
- •Differences between Implementations
- •Characters Change Meaning in Different Contexts
- •Regular Expressions Can Be Case Sensitive
- •Case-Sensitive and Case-Insensitive Matching
- •Case and Metacharacters
- •Continual Evolution in Techniques Supported
- •Multiple Solutions for a Single Problem
- •What You Want to Do with a Regular Expression
- •Replacing Text in Quantity
- •Regular Expression Tools
- •findstr
- •Microsoft Word
- •StarOffice Writer/OpenOffice.org Writer
- •Komodo Rx Package
- •PowerGrep
- •Microsoft Excel
- •JavaScript and JScript
- •VBScript
- •Visual Basic.NET
- •Java
- •Perl
- •MySQL
- •SQL Server 2000
- •W3C XML Schema
- •An Analytical Approach to Using Regular Expressions
- •Express and Document What You Want to Do in English
- •Consider the Regular Expression Options Available
- •Consider Sensitivity and Specificity
- •Create Appropriate Regular Expressions
- •Document All but Simple Regular Expressions
- •Document What You Expect the Regular Expression to Do
- •Document What You Want to Match
- •Test the Results of a Regular Expression
- •Matching Single Characters
- •Matching Sequences of Characters That Each Occur Once
- •Introducing Metacharacters
- •Matching Sequences of Different Characters
- •Matching Optional Characters
- •Matching Multiple Optional Characters
- •Other Cardinality Operators
- •The * Quantifier
- •The + Quantifier
- •The Curly-Brace Syntax
- •The {n} Syntax
- •The {n,m} Syntax
- •Exercises
- •Regular Expression Metacharacters
- •Thinking about Characters and Positions
- •The Period (.) Metacharacter
- •Matching Variably Structured Part Numbers
- •Matching a Literal Period
- •The \w Metacharacter
- •The \W Metacharacter
- •Digits and Nondigits
- •The \d Metacharacter
- •Canadian Postal Code Example
- •The \D Metacharacter
- •Alternatives to \d and \D
- •The \s Metacharacter
- •Handling Optional Whitespace
- •The \S Metacharacter
- •The \t Metacharacter
- •The \n Metacharacter
- •Escaped Characters
- •Finding the Backslash
- •Modifiers
- •Global Search
- •Case-Insensitive Search
- •Exercises
- •Introduction to Character Classes
- •Choice between Two Characters
- •Using Quantifiers with Character Classes
- •Using the \b Metacharacter in Character Classes
- •Selecting Literal Square Brackets
- •Using Ranges in Character Classes
- •Alphabetic Ranges
- •Use [A-z] With Care
- •Digit Ranges in Character Classes
- •Hexadecimal Numbers
- •IP Addresses
- •Reverse Ranges in Character Classes
- •A Potential Range Trap
- •Finding HTML Heading Elements
- •Metacharacter Meaning within Character Classes
- •The ^ metacharacter
- •How to Use the - Metacharacter
- •Negated Character Classes
- •Combining Positive and Negative Character Classes
- •POSIX Character Classes
- •The [:alnum:] Character Class
- •Exercises
- •String, Line, and Word Boundaries
- •The ^ Metacharacter
- •The ^ Metacharacter and Multiline Mode
- •The $ Metacharacter
- •The $ Metacharacter in Multiline Mode
- •Using the ^ and $ Metacharacters Together
- •Matching Blank Lines
- •Working with Dollar Amounts
- •Revisiting the IP Address Example
- •What Is a Word?
- •Identifying Word Boundaries
- •The \< Syntax
- •The \>Syntax
- •The \b Syntax
- •The \B Metacharacter
- •Less-Common Word-Boundary Metacharacters
- •Exercises
- •Grouping Using Parentheses
- •Parentheses and Quantifiers
- •Matching Literal Parentheses
- •U.S. Telephone Number Example
- •Alternation
- •Choosing among Multiple Options
- •Unexpected Alternation Behavior
- •Capturing Parentheses
- •Numbering of Captured Groups
- •Numbering When Using Nested Parentheses
- •Named Groups
- •Non-Capturing Parentheses
- •Back References
- •Exercises
- •Why You Need Lookahead and Lookbehind
- •The (? metacharacters
- •Lookahead
- •Positive Lookahead
- •Negative Lookahead
- •Positive Lookahead Examples
- •Positive Lookahead in the Same Document
- •Inserting an Apostrophe
- •Lookbehind
- •Positive Lookbehind
- •Negative Lookbehind
- •How to Match Positions
- •Adding Commas to Large Numbers
- •Exercises
- •What Are Sensitivity and Specificity?
- •Extreme Sensitivity, Awful Specificity
- •Email Addresses Example
- •Replacing Hyphens Example
- •The Sensitivity/Specificity Trade-Off
- •Sensitivity, Specificity, and Positional Characters
- •Sensitivity, Specificity, and Modes
- •Sensitivity, Specificity, and Lookahead and Lookbehind
- •How Much Should the Regular Expressions Do?
- •Abbreviations
- •Characters from Other Languages
- •Names
- •Sensitivity and How to Achieve It
- •Specificity and How to Maximize It
- •Exercises
- •Documenting Regular Expressions
- •Document the Problem Definition
- •Add Comments to Your Code
- •Making Use of Extended Mode
- •Know Your Data
- •Abbreviations
- •Proper Names
- •Incorrect Spelling
- •Creating Test Cases
- •Debugging Regular Expressions
- •Treacherous Whitespace
- •Backslashes Causing Problems
- •Considering Other Causes
- •The User Interface
- •Metacharacters Available
- •Quantifiers
- •The @ Quantifier
- •The {n,m} Syntax
- •Modes
- •Character Classes
- •Back References
- •Lookahead and Lookbehind
- •Lazy Matching versus Greedy Matching
- •Examples
- •Character Class Examples, Including Ranges
- •Whole Word Searches
- •Search-and-Replace Examples
- •Changing Name Structure Using Back References
- •Manipulating Dates
- •The Star Training Company Example
- •Regular Expressions in Visual Basic for Applications
- •Exercises
- •The User Interface
- •Metacharacters Available
- •Quantifiers
- •Modes
- •Character Classes
- •Alternation
- •Back References
- •Lookahead and Lookbehind
- •Search Example
- •Search-and-Replace Example
- •Online Chats
- •POSIX Character Classes
- •Matching Numeric Digits
- •Exercises
- •Introducing findstr
- •Finding Literal Text
- •Quantifiers
- •Character Classes
- •Command-Line Switch Examples
- •The /v Switch
- •The /a Switch
- •Single File Examples
- •Simple Character Class Example
- •Find Protocols Example
- •Multiple File Example
- •A Filelist Example
- •Exercises
- •The PowerGREP Interface
- •A Simple Find Example
- •The Replace Tab
- •The File Finder Tab
- •Syntax Coloring
- •Other Tabs
- •Numeric Digits and Alphabetic Characters
- •Quantifiers
- •Back References
- •Alternation
- •Line Position Metacharacters
- •Word-Boundary Metacharacters
- •Lookahead and Lookbehind
- •Longer Examples
- •Finding HTML Horizontal Rule Elements
- •Matching Time Example
- •Exercises
- •The Excel Find Interface
- •Escaping Wildcard Characters
- •Using Wildcards in Data Forms
- •Using Wildcards in Filters
- •Exercises
- •Using LIKE with Regular Expressions
- •The % Metacharacter
- •The _ Metacharacter
- •Character Classes
- •Negated Character Classes
- •Using Full-Text Search
- •Using The CONTAINS Predicate
- •Document Filters on Image Columns
- •Exercises
- •Using the _ and % Metacharacters
- •Testing Matching of Literals: _ and % Metacharacters
- •Using Positional Metacharacters
- •Using Character Classes
- •Quantifiers
- •Social Security Number Example
- •Exercises
- •The Interface to Metacharacters in Microsoft Access
- •Creating a Hard-Wired Query
- •Creating a Parameter Query
- •Using the ? Metacharacter
- •Using the * Metacharacter
- •Using the # Metacharacter
- •Using the # Character with Date/Time Data
- •Using Character Classes in Access
- •Exercises
- •The RegExp Object
- •Attributes of the RegExp Object
- •The Other Properties of the RegExp Object
- •The test() Method of the RegExp Object
- •The exec() Method of the RegExp Object
- •The String Object
- •Metacharacters in JavaScript and JScript
- •SSN Validation Example
- •Exercises
- •The RegExp Object and How to Use It
- •Quantifiers
- •Positional Metacharacters
- •Character Classes
- •Word Boundaries
- •Lookahead
- •Grouping and Nongrouping Parentheses
- •Exercises
- •The System.Text.RegularExpressions namespace
- •A Simple Visual Basic .NET Example
- •The Classes of System.Text.RegularExpressions
- •The Regex Object
- •Using the Match Object and Matches Collection
- •Using the Match.Success Property and Match.NextMatch Method
- •The GroupCollection and Group Classes
- •The CaptureCollection and Capture Class
- •The RegexOptions Enumeration
- •Case-Insensitive Matching: The IgnoreCase Option
- •Multiline Matching: The Effect on the ^ and $ Metacharacters
- •Right to Left Matching: The RightToLeft Option
- •Lookahead and Lookbehind
- •Exercises
- •An Introductory Example
- •The Classes of System.Text.RegularExpressions
- •The Regex Class
- •The Options Property of the Regex Class
- •Regex Class Methods
- •The CompileToAssembly() Method
- •The GetGroupNames() Method
- •The GetGroupNumbers() Method
- •GroupNumberFromName() and GroupNameFromNumber() Methods
- •The IsMatch() Method
- •The Match() Method
- •The Matches() Method
- •The Replace() Method
- •The Split() Method
- •Using the Static Methods of the Regex Class
- •The IsMatch() Method as a Static
- •The Match() Method as a Static
- •The Matches() Method as a Static
- •The Replace() Method as a Static
- •The Split() Method as a Static
- •The Match and Matches Classes
- •The Match Class
- •The GroupCollection and Group Classes
- •The RegexOptions Class
- •The IgnorePatternWhitespace Option
- •Metacharacters Supported in Visual C# .NET
- •Using Named Groups
- •Using Back References
- •Exercise
- •The ereg() Set of Functions
- •The ereg() Function
- •The ereg() Function with Three Arguments
- •The eregi() Function
- •The ereg_replace() Function
- •The eregi_replace() Function
- •The split() Function
- •The spliti() Function
- •The sql_regcase() Function
- •Perl Compatible Regular Expressions
- •Pattern Delimiters in PCRE
- •Escaping Pattern Delimiters
- •Matching Modifiers in PCRE
- •Using the preg_match() Function
- •Using the preg_match_all() Function
- •Using the preg_grep() Function
- •Using the preg_quote() Function
- •Using the preg_replace() Function
- •Using the preg_replace_callback() Function
- •Using the preg_split() Function
- •Supported Metacharacters with ereg()
- •Using POSIX Character Classes with PHP
- •Supported Metacharacters with PCRE
- •Positional Metacharacters
- •Character Classes in PHP
- •Documenting PHP Regular Expressions
- •Exercises
- •W3C XML Schema Basics
- •Tools for Using W3C XML Schema
- •Comparing XML Schema and DTDs
- •How Constraints Are Expressed in W3C XML Schema
- •W3C XML Schema Datatypes
- •Derivation by Restriction
- •Unicode and W3C XML Schema
- •Unicode Overview
- •Using Unicode Character Classes
- •Matching Decimal Numbers
- •Mixing Unicode Character Classes with Other Metacharacters
- •Unicode Character Blocks
- •Using Unicode Character Blocks
- •Metacharacters Supported in W3C XML Schema
- •Positional Metacharacters
- •Matching Numeric Digits
- •Alternation
- •Using the \w and \s Metacharacters
- •Escaping Metacharacters
- •Exercises
- •Introduction to the java.util.regex Package
- •Obtaining and Installing Java
- •The Pattern Class
- •Using the matches() Method Statically
- •Two Simple Java Examples
- •The Properties (Fields) of the Pattern Class
- •The CASE_INSENSITIVE Flag
- •Using the COMMENTS Flag
- •The DOTALL Flag
- •The MULTILINE Flag
- •The UNICODE_CASE Flag
- •The UNIX_LINES Flag
- •The Methods of the Pattern Class
- •The compile() Method
- •The flags() Method
- •The matcher() Method
- •The matches() Method
- •The pattern() Method
- •The split() Method
- •The Matcher Class
- •The appendReplacement() Method
- •The appendTail() Method
- •The end() Method
- •The find() Method
- •The group() Method
- •The groupCount() Method
- •The lookingAt() Method
- •The matches() Method
- •The pattern() Method
- •The replaceAll() Method
- •The replaceFirst() Method
- •The reset() Method
- •The start() Method
- •The PatternSyntaxException Class
- •Using the \d Metacharacter
- •Character Classes
- •The POSIX Character Classes in the java.util.regex Package
- •Unicode Character Classes and Character Blocks
- •Using Escaped Characters
- •Using Methods of the String Class
- •Using the matches() Method
- •Using the replaceFirst() Method
- •Using the replaceAll() Method
- •Using the split() Method
- •Exercises
- •Obtaining and Installing Perl
- •Creating a Simple Perl Program
- •Basics of Perl Regular Expression Usage
- •Using the m// Operator
- •Using Other Regular Expression Delimiters
- •Matching Using Variable Substitution
- •Using the s/// Operator
- •Using s/// with the Global Modifier
- •Using s/// with the Default Variable
- •Using the split Operator
- •Using Quantifiers in Perl
- •Using Positional Metacharacters
- •Captured Groups in Perl
- •Using Back References in Perl
- •Using Alternation
- •Using Character Classes in Perl
- •Using Lookahead
- •Using Lookbehind
- •Escaping Metacharacters
- •A Simple Perl Regex Tester
- •Exercises
- •Index
Chapter 24
Figure 24-5
How Constraints Are Expressed in W3C XML Schema
In one sense, W3C XML Schema is all about applying constraints. One type of constraint is limiting how elements and attributes can be structured inside an XML instance document belonging to the class of XML documents to which the schema applies. Another aspect of W3C XML Schema constraining the content of a class of XML documents is in constraining the content allowed as the value contained in an element or attribute.
Two kinds of types can exist as the content of an element: a complex type (indicated by an xs:complexType element in the schema) and a simple type (which may be indicated by an xs:simpleType element in the schema). This chapter focuses on constraining the values allowed in simple types in an XML instance document.
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Regular Expressions in W3C XML Schema
W3C XML Schema Datatypes
In the other uses of regular expressions you have seen in this book, the regular expression has been applied to a string value. In W3C XML Schema, it is possible to use regular expressions together with other datatypes.
The following table summarizes the datatypes built into W3C XML Schema. Datatypes are shown as having the xs namespace prefix as an indication that they belong to the XML namespace http://www.w3.org/ 2001/XMLSchema. Datatypes can be viewed as primitive or derived built-in datatypes.
Datatype |
Description |
|
|
xs:anyType |
Functions as the root of the type hierarchy. Types derived from |
|
xs:anyType can be a complex type or a simple type. |
xs:anySimpleType |
The base type for all simple types. |
xs:string |
A sequence of XML characters of finite length. |
xs:boolean |
Expresses the binary notion of true and false. |
xs:base64Binary |
Represents base-64 encoded binary data. |
xs:hexBinary |
Represents hexadecimal encoded binary data. |
xs:float |
Represents an IEEE single-precision 32-bit floating-point number. |
xs:decimal |
Represents arbitrary precision decimal numbers. |
xs:double |
Represents an IEEE double-precision 64-bit floating-point number. |
xs:anyURI |
Represents a Uniform Resource Identifier, whether absolute or rela- |
|
tive, and may include a fragment identifier. |
xs:QName |
An XML namespace-qualified name. |
xs:NOTATION |
Represents an XML 1.0 NOTATION. |
xs:duration |
Represents a duration with Gregorian year, month, day, hour, |
|
minute, and seconds components. |
xs:dateTime |
Represents a specific instant of time. |
xs:time |
Represents a specific instant of time that recurs every day. |
xs:date |
Represents a specified calendar day. |
xs:gYearMonth |
Represents the year and month parts of an xs:dateTime. |
xs:gMonthDay |
Represents a specified day of the year, such as September 25. |
xs:gDay |
Represents a specified day of the month, such as the 25th. |
xs:gMonth |
Represents a specified Gregorian calendar month. |
|
|
In addition to the datatypes already listed, there are datatypes derived, directly or indirectly, from the xs:string and xs:decimal datatypes.
599
Chapter 24
The following table summarizes the datatypes that are derived from xs:string.
Derived Datatype |
Description |
|
|
xs:normalizedString |
The base type is xs:string. The xs:normalizedString type is the |
|
set of strings that does not contain the characters carriage return |
|
(#xD), linefeed (#xA), and tab (#x9). |
xs:token |
The base type is xs:string. This datatype is the set of strings that |
|
does not contain the linefeed (#xA) or tab (#x9) characters, nor any |
|
leading or trailing space characters (#x20) or any doubled internal |
|
space characters. |
xs:language |
The base type is xs:token. This datatype is the set of xs:token val- |
|
ues that are language identifiers in the XML 1.0 (second edition) |
|
specification. |
xs:Name |
The base type is xs:token. This datatype is the set of strings that |
|
are legal XML names, as defined in the XML 1.0 (second edition) |
|
specification. |
xs:NCName |
The base type is xs:Name. This datatype is the set of strings that are |
|
XML names but do not contain a colon character. |
xs:ID |
The base type is xs:NCName. This datatype represents values of ID |
|
type that are also NCNames. |
xs:IDREF |
The base type is xs:NCName. This datatype is the set of strings that |
|
represent values of type IDREF, which are NCNames. |
xs:IDREFS |
The item type is xs:IDREF. This datatype is a list of whitespace-sep- |
|
arated values, each of which is of type xs:IDREF. |
xs:NMTOKEN |
The base type is xs:token. This datatype is the set of xs:token val- |
|
ues that match the NMTOKEN definition in XML 1.0 (second edition). |
xs:NMTOKENS |
The item type is xs:NMTOKEN. This datatype is a list of whitespace- |
|
separated values, each of which is of type xs:NMTOKEN. |
xs:ENTITY |
The base type is xs:NCName. This datatype represents values that are of |
|
ENTITY type, as defined in the XML 1.0 (second edition) specification. |
xs:ENTITIES |
The item type is xs:ENTITY. This datatype is a list of whitespace- |
|
separated values, each of which is of type xs:ENTITY. |
|
|
The following table summarizes the built-in datatypes that are derived, directly or indirectly, from the xs:decimal datatype.
600
|
|
Regular Expressions in W3C XML Schema |
|
|
|
|
Derived Datatype |
Description |
|
|
|
|
xs:integer |
The base type is xs:decimal. This datatype represents positive and |
|
|
negative integer values. |
|
xs:nonPositiveInteger |
The base type is xs:integer. This datatype represents negative inte- |
|
|
gers and zero. |
|
xs:negativeInteger |
The base type is xs:nonPositiveInteger. This datatype represents |
|
|
negative integers. |
|
xs:long |
The base type is xs:integer. This datatype represents integer val- |
|
|
ues from -9223372036854775808 to 9223372036854775807. |
|
xs:int |
The base type is xs:long. This datatype represents integer values |
|
|
from -2147483648 to 2147483647 inclusive. |
|
xs:short |
The base type is xs:int. This datatype represents integer values |
|
|
from -32768 to 32767 inclusive. |
|
xs:byte |
The base type is xs:short. This datatype represents integer values |
|
|
from -128 to 127 inclusive. |
|
xs:nonNegativeInteger |
The base type is xs:integer. This datatype represents integer val- |
|
|
ues that are positive integers and zero. |
|
xs:unsignedLong |
The base type is xs:nonNegativeInteger. This datatype represents |
|
|
integer values from 0 to 18446744073709551615. |
|
xs:unsignedInt |
The base type is xs:unsignedLong. This datatype represents integer |
|
|
values from 0 to 4294967295 inclusive. |
|
xs:unsignedShort |
The base type is xs:unsignedInt. This datatype represents integer |
|
|
values from 0 to 65535 inclusive. |
|
xs:unsignedByte |
The base type is xs:unsignedShort. This datatype represents inte- |
|
|
ger values from 0 to 255 inclusive. |
|
xs:positiveInteger |
The base type is xs:nonNegativeInteger. This datatype represents |
|
|
integer values of 1 and greater. |
|
|
|
Fuller details on how the built-in datatypes are specified can be found in XML Schema Part 2 at www.w3.org/TR/2001/REC-xmlschema-2-20010502, XML 1.0 (second edition) at www.w3.org/TR/ 2000/WD-xml-2e-20000814, and Namespaces in XML at www.w3.org/TR/REC-xml-names.
The programmer can develop custom types from these built-in types by any of the three mechanisms in the following list:
Derivation by restriction — Values of an existing datatype are constrained by restricting the allowed values.
Derivation by list — A list of values of a built-in or user-defined datatype.
Derivation by union — The user-defined datatype is the union of two other datatypes (which can be built-in datatypes or user-defined datatypes).
601