jregex
Class Pattern

java.lang.Object
  |
  +--jregex.Pattern

All Implemented Interfaces:

REFlags, java.io.Serializable

Direct Known Subclasses:

PathPattern, WildcardPattern

public class Pattern

extends java.lang.Object

implements java.io.Serializable, REFlags

A handle for a precompiled regular expression.
To match a regular expression myExpr against a text myString one should first create a Pattern object:

 Pattern p=new Pattern(myExpr);
 

then obtain a Matcher object:

 Matcher matcher=p.matcher(myText);
 

The latter is an automaton that actually performs a search. It provides the following methods:

search for matching substrings : matcher.find() or matcher.findAll();

test whether the text matches the whole pattern : matcher.matches();

test whether the text matches the beginning of the pattern : matcher.matchesPrefix();

search with custom options : matcher.find(int options)

Flags
Flags (see REFlags interface) change the meaning of some regular expression elements at compiletime. These flags may be passed both as string(see Pattern(String,String)) and as bitwise OR of:

REFlags.IGNORE_CASE - enables case insensitivity

REFlags.MULTILINE - forces "^" and "$" to match both at the start and the end of line;

REFlags.DOTALL - forces "." to match eols('\r' and '\n' in ASCII);

REFlags.IGNORE_SPACES - literal spaces in expression are ignored for better readability;

REFlags.UNICODE - the predefined classes('\w','\d',etc) are referenced to Unicode;

REFlags.XML_SCHEMA - permits XML Schema regular expressions syntax extentions.

Multithreading
Pattern instances are thread-safe, i.e. the same Pattern object may be used by any number of threads simultaniously. On the other hand, the Matcher objects are NOT thread safe, so, given a Pattern instance, each thread must obtain and use its own Matcher.

See Also:

REFlags, Matcher, Matcher.setTarget(java.lang.String), Matcher.setTarget(java.lang.String,int,int), Matcher.setTarget(char[],int,int), Matcher.setTarget(java.io.Reader,int), MatchResult, MatchResult.group(int), MatchResult.start(int), MatchResult.end(int), MatchResult.length(int), MatchResult.charAt(int,int), MatchResult.prefix(), MatchResult.suffix(), Serialized Form

Fields inherited from interface jregex.REFlags

DEFAULT, DOTALL, IGNORE_CASE, IGNORE_SPACES, MULTILINE, UNICODE, XML_SCHEMA

Constructor Summary

protected	Pattern()
	Pattern(java.lang.String regex) Compiles an expression with default flags.
	Pattern(java.lang.String regex, int flags) Compiles a regular expression using REFlags.
	Pattern(java.lang.String regex, java.lang.String flags) Compiles a regular expression using Perl5-style flags.

Method Summary

protected void	compile(java.lang.String regex, int flags)
int	groupCount() How many capturing groups this expression includes?
java.lang.Integer	groupId(java.lang.String name) Get numeric id for a group name.
Matcher	matcher() Returns a targetless matcher.
Matcher	matcher(char[] data, int start, int end) Returns a matcher for a specified region.
Matcher	matcher(MatchResult res, int groupId) Returns a matcher for a match result (in a performance-friendly way).
Matcher	matcher(MatchResult res, java.lang.String groupName) Just as above, yet with symbolic group name.
Matcher	matcher(java.io.Reader text, int length) Returns a matcher taking a text stream as target.
Matcher	matcher(java.lang.String s) Returns a matcher for a specified string.
boolean	matches(java.lang.String s) A shorthand for Pattern.matcher(String).matches().
Replacer	replacer(java.lang.String expr) Returns a replacer of a pattern by specified perl-like expression.
Replacer	replacer(Substitution model) Returns a replacer will substitute all occurences of a pattern through applying a user-defined substitution model.
boolean	startsWith(java.lang.String s) A shorthand for Pattern.matcher(String).matchesPrefix().
RETokenizer	tokenizer(char[] data, int off, int len) Tokenizes a specified region by an occurences of the pattern.
RETokenizer	tokenizer(java.io.Reader in, int length) Tokenizes a specified region by an occurences of the pattern.
RETokenizer	tokenizer(java.lang.String text) Tokenizes a text by an occurences of the pattern.
java.lang.String	toString_d() Returns a less or more readable representation of a bytecode for the pattern.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Pattern

protected Pattern()
           throws PatternSyntaxException

Pattern

public Pattern(java.lang.String regex)
        throws PatternSyntaxException

Compiles an expression with default flags.

Parameters:

regex - the Perl5-compatible regular expression string.

Throws:

PatternSyntaxException - if the argument doesn't correspond to perl5 regex syntax.

See Also:

Pattern(java.lang.String,java.lang.String), Pattern(java.lang.String,int)

Pattern

public Pattern(java.lang.String regex,
               java.lang.String flags)
        throws PatternSyntaxException

Compiles a regular expression using Perl5-style flags. The flag string should consist of letters 'i','m','s','x','u','X'(the case is significant) and a hyphen. The meaning of letters:

• i - case insensitivity, corresponds to REFLlags.IGNORE_CASE;
• m - multiline treatment(BOLs and EOLs affect the '^' and '$'), corresponds to REFLlags.MULTILINE flag;
• s - single line treatment('.' matches \r's and \n's),corresponds to REFLlags.DOTALL;
• x - extended whitespace comments (spaces and eols in the expression are ignored), corresponds to REFLlags.IGNORE_SPACES.
• u - predefined classes are regarded as belonging to Unicode, corresponds to REFLlags.UNICODE; this may yield some performance penalty.
• X - compatibility with XML Schema, corresponds to REFLlags.XML_SCHEMA.

Parameters:

regex - the Perl5-compatible regular expression string.

flags - the Perl5-compatible flags.

Throws:

PatternSyntaxException - if the argument doesn't correspond to perl5 regex syntax. see REFlags

Pattern

public Pattern(java.lang.String regex,
               int flags)
        throws PatternSyntaxException

Compiles a regular expression using REFlags. The flags parameter is a bitwise OR of the folloing values:

• REFLlags.IGNORE_CASE - case insensitivity, corresponds to 'i' letter;
• REFLlags.MULTILINE - multiline treatment(BOLs and EOLs affect the '^' and '$'), corresponds to 'm';
• REFLlags.DOTALL - single line treatment('.' matches \r's and \n's),corresponds to 's';
• REFLlags.IGNORE_SPACES - extended whitespace comments (spaces and eols in the expression are ignored), corresponds to 'x'.
• REFLlags.UNICODE - predefined classes are regarded as belonging to Unicode, corresponds to 'u'; this may yield some performance penalty.
• REFLlags.XML_SCHEMA - compatibility with XML Schema, corresponds to 'X'.

Parameters:

regex - the Perl5-compatible regular expression string.

flags - the Perl5-compatible flags.

Throws:

PatternSyntaxException - if the argument doesn't correspond to perl5 regex syntax. see REFlags

Method Detail

compile

protected void compile(java.lang.String regex,
                       int flags)
                throws PatternSyntaxException

groupCount

public int groupCount()

How many capturing groups this expression includes?

groupId

public java.lang.Integer groupId(java.lang.String name)

Get numeric id for a group name.

Returns:

null if no such name found.

See Also:

MatchResult.group(java.lang.String), MatchResult.isCaptured(java.lang.String)

matches

public boolean matches(java.lang.String s)

A shorthand for Pattern.matcher(String).matches().

Parameters:

s - the target

Returns:

true if the entire target matches the pattern

See Also:

Matcher.matches(), Matcher.matches(String)

startsWith

public boolean startsWith(java.lang.String s)

A shorthand for Pattern.matcher(String).matchesPrefix().

Parameters:

s - the target

Returns:

true if the entire target matches the beginning of the pattern

See Also:

Matcher.matchesPrefix()

matcher

public Matcher matcher()

Returns a targetless matcher. Don't forget to supply a target.

matcher

public Matcher matcher(java.lang.String s)

Returns a matcher for a specified string.

matcher

public Matcher matcher(char[] data,
                       int start,
                       int end)

Returns a matcher for a specified region.

matcher

public Matcher matcher(MatchResult res,
                       int groupId)

Returns a matcher for a match result (in a performance-friendly way). groupId parameter specifies which group is a target.

Parameters:

groupId - which group is a target; either positive integer(group id), or one of MatchResult.MATCH,MatchResult.PREFIX,MatchResult.SUFFIX,MatchResult.TARGET.

matcher

public Matcher matcher(MatchResult res,
                       java.lang.String groupName)

Just as above, yet with symbolic group name.

Throws:

NullPointerException - if there is no group with such name

matcher

public Matcher matcher(java.io.Reader text,
                       int length)
                throws java.io.IOException

Returns a matcher taking a text stream as target. Note that this is not a true POSIX-style stream matching, i.e. the whole length of the text is preliminary read and stored in a char array.

Parameters:

text - a text stream

len - the length to read from a stream; if len is -1, the whole stream is read in.

Throws:

java.io.IOException - indicates an IO problem

OutOfMemoryException - if a stream is too lengthy

replacer

public Replacer replacer(java.lang.String expr)

Returns a replacer of a pattern by specified perl-like expression. Such replacer will substitute all occurences of a pattern by an evaluated expression ("$&" and "$0" will substitute by the whole match, "$1" will substitute by group#1, etc). Example:

 String text="The quick brown fox jumped over the lazy dog";
 Pattern word=new Pattern("\\w+");
 System.out.println(word.replacer("[$&]").replace(text));
 //prints "[The] [quick] [brown] [fox] [jumped] [over] [the] [lazy] [dog]"
 Pattern swap=new Pattern("(fox|dog)(.*?)(fox|dog)");
 System.out.println(swap.replacer("$3$2$1").replace(text));
 //prints "The quick brown dog jumped over the lazy fox"
 Pattern scramble=new Pattern("(\\w+)(.*?)(\\w+)");
 System.out.println(scramble.replacer("$3$2$1").replace(text));
 //prints "quick The fox brown over jumped lazy the dog"
 

Parameters:

expr - a perl-like expression, the "$&" and "${&}" standing for whole match, the "$N" and "${N}" standing for group#N, and "${Foo}" standing for named group Foo.

See Also:

Replacer

replacer

public Replacer replacer(Substitution model)

Returns a replacer will substitute all occurences of a pattern through applying a user-defined substitution model.

Parameters:

model - a Substitution object which is in charge for match substitution

See Also:

Replacer

tokenizer

public RETokenizer tokenizer(java.lang.String text)

Tokenizes a text by an occurences of the pattern. Note that a series of adjacent matches are regarded as a single separator. The same as new RETokenizer(Pattern,String);

See Also:

RETokenizer, RETokenizer.RETokenizer(jregex.Pattern,java.lang.String)

tokenizer

public RETokenizer tokenizer(char[] data,
                             int off,
                             int len)

Tokenizes a specified region by an occurences of the pattern. Note that a series of adjacent matches are regarded as a single separator. The same as new RETokenizer(Pattern,char[],int,int);

See Also:

RETokenizer, RETokenizer.RETokenizer(jregex.Pattern,char[],int,int)

tokenizer

public RETokenizer tokenizer(java.io.Reader in,
                             int length)
                      throws java.io.IOException

Tokenizes a specified region by an occurences of the pattern. Note that a series of adjacent matches are regarded as a single separator. The same as new RETokenizer(Pattern,Reader,int);

See Also:

RETokenizer, RETokenizer.RETokenizer(jregex.Pattern,java.io.Reader,int)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

toString_d

public java.lang.String toString_d()

Returns a less or more readable representation of a bytecode for the pattern.