org.plumelib.util

Class RegexUtil

java.lang.Object

org.plumelib.util.RegexUtil

public final class RegexUtil
extends java.lang.Object

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

For an example of intended use, see section Testing whether a string is a regular expression in the Checker Framework manual.

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 java.lang.String	asRegex(java.lang.String s) Returns the argument as a @Regex String if it is a regex, otherwise throws an error.
static java.lang.String	asRegex(java.lang.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(java.lang.String s) Returns true if the argument is a syntactically valid regular expression.
static boolean	isRegex(java.lang.String s, int groups) Returns true if the argument is a syntactically valid regular expression with at least the given number of groups.
static @Nullable java.lang.String	regexError(java.lang.String s) Returns null if the argument is a syntactically valid regular expression.
static @Nullable java.lang.String	regexError(java.lang.String s, int groups) Returns null if the argument is a syntactically valid regular expression with at least the given number of groups.
static @Nullable java.util.regex.PatternSyntaxException	regexException(java.lang.String s) Returns null if the argument is a syntactically valid regular expression.
static @Nullable java.util.regex.PatternSyntaxException	regexException(java.lang.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

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

Method Detail

isRegex

@Pure
 @EnsuresQualifierIf(result=true,
                    expression="#1",
                    qualifier=org.checkerframework.checker.regex.qual.Regex.class)
public static boolean isRegex(java.lang.String s)

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

Parameters:

s - string to check for being a regular expression

Returns:

true iff s is a regular expression

isRegex

@Pure
 @EnsuresQualifierIf(result=true,
                    expression="#1",
                    qualifier=org.checkerframework.checker.regex.qual.Regex.class)
public static boolean isRegex(java.lang.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 - string to check for being a regular expression

groups - number of groups expected

Returns:

true iff s is a regular expression with groups groups

isRegex

@Pure
 @EnsuresQualifierIf(result=true,
                    expression="#1",
                    qualifier=org.checkerframework.checker.regex.qual.Regex.class)
public static boolean isRegex(char c)

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

Parameters:

c - char to check for being a regular expression

Returns:

true iff c is a regular expression

regexError

@SideEffectFree
public static @Nullable java.lang.String regexError(java.lang.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 - string to check for being a regular expression

Returns:

null, or a string describing why the argument is not a regex

regexError

@SideEffectFree
public static @Nullable java.lang.String regexError(java.lang.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 - string to check for being a regular expression

groups - number of groups expected

Returns:

null, or a string describing why the argument is not a regex

regexException

@SideEffectFree
public static @Nullable java.util.regex.PatternSyntaxException regexException(java.lang.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 - string to check for being a regular expression

Returns:

null, or a PatternSyntaxException describing why the argument is not a regex

regexException

@SideEffectFree
public static @Nullable java.util.regex.PatternSyntaxException regexException(java.lang.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 - string to check for being a regular expression

groups - number of groups expected

Returns:

null, or a PatternSyntaxException describing why the argument is not a regex

asRegex

@SideEffectFree
public static java.lang.String asRegex(java.lang.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. It should be very rarely needed.

Parameters:

s - string to check for being a regular expression

Returns:

its argument

Throws:

java.lang.Error - if argument is not a regex

asRegex

@SideEffectFree
public static java.lang.String asRegex(java.lang.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. It should be very rarely needed.

Parameters:

s - string to check for being a regular expression

groups - number of groups expected

Returns:

its argument

Throws:

java.lang.Error - if argument is not a regex