Predefined character class replacement inside square brackets is incorrect about generex HOT 1 OPEN

Problem

It should be also taken into consideration that the backslash in the character class could have been escaped.

Input: \\d (Java string literal "\\\\d")

Expected output:

• transformed regex: \\d (no change)
• matched string: \d

Actual output:

• transformed regex: \[0-9]
• matched string: [0-9]

Proposed solution

Pattern.compile(
	"(?<!\\\\)" +			// (?<!\\)	no preceding backslash allowed
	"(?<slashes>(\\\\\\\\)*)" +	// (\\\\)*	literal backslash allowed {0,} times
	"\\\\d"				// \\d		single backslash and the character class letter
);

Don't forget to include slashes when replacing, they had to be captured (in pairs) because the negative look-behind does not allow infinite *.

from generex.