org.apache.hadoop.chukwa.util

Class RegexUtil

java.lang.Object

org.apache.hadoop.chukwa.util.RegexUtil

public class RegexUtil
extends Object

Utility methods for regular expressions, most notably for testing whether a string is a regular expression.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RegexUtil.CheckedPatternSyntaxException A checked version of PatternSyntaxException.

Method Summary

Modifier and Type	Method and Description
static String	asRegex(String s) Returns the argument as a @Regex String if it is a regex, otherwise throws an error.
static String	asRegex(String s, int groups) Returns the argument as a @Regex(groups) String if it is a regex with at least the given number of groups, otherwise throws an error.
static boolean	isRegex(char c) Returns true if the argument is a syntactically valid regular expression.
static boolean	isRegex(String s) Returns true if the argument is a syntactically valid regular expression.
static boolean	isRegex(String s, int groups) Returns true if the argument is a syntactically valid regular expression with at least the given number of groups.
static String	regexError(String s) Returns null if the argument is a syntactically valid regular expression.
static String	regexError(String s, int groups) Returns null if the argument is a syntactically valid regular expression with at least the given number of groups.
static PatternSyntaxException	regexException(String s) Returns null if the argument is a syntactically valid regular expression.
static PatternSyntaxException	regexException(String s, int groups) Returns null if the argument is a syntactically valid regular expression with at least the given number of groups.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

isRegex

public static boolean isRegex(String s)

Returns true if the argument is a syntactically valid regular expression.

Parameters:

s - is regular expression

Returns:

true if there is a match

isRegex

public static boolean isRegex(String s,
                              int groups)

Returns true if the argument is a syntactically valid regular expression with at least the given number of groups.

Parameters:

s - is regular expression

groups - is number of groups to match

Returns:

true if there is a match

isRegex

public static boolean isRegex(char c)

Returns true if the argument is a syntactically valid regular expression.

Parameters:

c - is a character

Returns:

true if there is a match

regexError

public static String regexError(String s)

Returns null if the argument is a syntactically valid regular expression. Otherwise returns a string describing why the argument is not a regex.

Parameters:

s - is regular expression

Returns:

null if s is a regular expression

regexError

public static String regexError(String s,
                                int groups)

Returns null if the argument is a syntactically valid regular expression with at least the given number of groups. Otherwise returns a string describing why the argument is not a regex.

Parameters:

s - is regular expression

groups - is number of groups to match

Returns:

null if s is a regular expression

regexException

public static PatternSyntaxException regexException(String s)

Returns null if the argument is a syntactically valid regular expression. Otherwise returns a PatternSyntaxException describing why the argument is not a regex.

Parameters:

s - is regular expression

Returns:

null if s is a regular expression

regexException

public static PatternSyntaxException regexException(String s,
                                                    int groups)

Returns null if the argument is a syntactically valid regular expression with at least the given number of groups. Otherwise returns a PatternSyntaxException describing why the argument is not a regex.

Parameters:

s - is regular expression

groups - is number of groups to match

Returns:

null if s is a regular expression

asRegex

public static String asRegex(String s)

Returns the argument as a @Regex String if it is a regex, otherwise throws an error. The purpose of this method is to suppress Regex Checker warnings. Once the the Regex Checker supports flow-sensitivity, it should be very rarely needed.

Parameters:

s - is a regular expression

Returns:

null if s is a regular expression

asRegex

public static String asRegex(String s,
                             int groups)

Returns the argument as a @Regex(groups) String if it is a regex with at least the given number of groups, otherwise throws an error. The purpose of this method is to suppress Regex Checker warnings. Once the the Regex Checker supports flow-sensitivity, it should be very rarely needed.

Parameters:

s - is a regular expression

groups - is number of group to match

Returns:

null if s is a regular expression