How to Handle Unicode Characters in Java Regular Expressions Using \w and \b Equivalents?

Unicode Equivalents for w and b in Java Regular Expressions?

Java's implementation of Perl-style character class shortcuts (w, b, s, etc.) is limited to ASCII characters. To match Unicode characters correctly, you need a better way to rewrite these shortcuts.

Solution:

Utilize a custom function to rewrite the following charclass escapes:

\w \W \s \S \v \V \h \H \d \D \b \B \X \R

Rewritten Definitions:

\s => [^\u0009-\u000D\u0020\u0085\u00A0\u1680\u180E\u2000-\u200A\u2028\u2029\u202F\u205F\u3000]
\S => [^\u0009-\u000D\u0020\u0085\u00A0\u1680\u180E\u2000-\u200A\u2028\u2029\u202F\u205F\u3000]

\v => [\u000A-\u000D\u0085\u2028\u2029]
\V => [^\u000A-\u000D\u0085\u2028\u2029]

\h => [\u0009\u0020\u00A0\u1680\u180E\u2000-\u200A\u202F\u205F\u3000]
\H => [^\u0009\u0020\u00A0\u1680\u180E\u2000\u2001-\u200A\u202F\u205F\u3000]

\w => [\pL\pM\p{Nd}\p{Nl}\p{Pc}[\p{InEnclosedAlphanumerics}&&\p{So}]]
\W => [^\pL\pM\p{Nd}\p{Nl}\p{Pc}[\p{InEnclosedAlphanumerics}&&\p{So}]]

\b => (?:(?<=[a-z0-9])(?![a-z0-9])|(?<![a-z0-9])(?=[a-z0-9]))
\B => (?:(?<=[a-z0-9])(?=[a-z0-9])|(?<![a-z0-9])(?![a-z0-9]))

\d => \p{Nd}
\D => \P{Nd}

\R => (?:(?>\u000D\u000A)|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029])

\X => (?>\PM\pM*)

Boundary Considerations:

Java's b and B are not solely bound to w. A rewritten b using A(?:AB|BC) construction can search for boundaries where:

• IF follows word ==> THEN doesn't precede word
• ELSIF doesn't follow word ==> THEN does precede word

A rewritten B using A(?:BC|AB) construction can search for non-boundaries where:

• IF follows word ==> THEN does precede word
• ELSIF doesn't follow word ==> THEN doesn't precede word

Complete Rewriting Function:

Grab the source code to get the full rewriting function mentioned above.

Additional Features:

• Unicode character input in logical code points
• Convenience definitions for natural-language words, dashes, hyphens, and apostrophes
• Augmentation of regex escapes and unescaping of string escapes

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