Feature Request: Replacement Text Case Conversion

[billynoah]

Would adding case conversion be difficult? Would be a very useful feature!

http://www.regular-expressions.info/replacecase.html

PCRE2 supports case conversion in replacement strings when using PCRE2_SUBSTITUTE_EXTENDED. \U converts everything that follows to uppercase. \L converts everything that follows to lowercase. \u converts the next character to uppercase. \l converts the next character to lowercase. \E turns off case conversion. As in Perl, the case conversion affects both literal text in your replacement string and the text inserted by backreferences.

Unlike in Perl, in PCRE2 \U, \L, \u, and \l all stop any preceding case conversion. So you cannot combine \L and \u, for example, to make the first character uppercase and the remainder lowercase. \L\u makes the first character uppercase and leaves the rest unchanged, just like \u. \u\L makes all characters lowercase, just like \L.

In PCRE2, case conversion runs through conditionals. Any case conversion in effect before the conditional also applies to the conditional. If the conditional contains its own case conversion escapes in the part of the conditional that is actually used, then those remain in effect after the conditional. So you could use ${1:+\U:\L}${2} to insert the text matched by the second capturing group in uppercase if the first group participated, and in lowercase if it didn't.