Escaping partial regex pattern

Question

Hello,

I search to built a pattern composed by some fixed parts and a variable (in reality Business Unit name). In fact, there is high chance that the variable contains some specific regex characters which can be recognize as regex control ones (i.e + or *).

Is there any regex tag that notice that a pattern subpart should be considered only as text, and ignore specific char meaning?

some kind of :

regex_fixed_part [escape]business + unit[/espace] regex_fixed_part

here, business + unit will be replaced in the parser by business \+ unit

Obviously, I could escape manually all regex char, but I search a more tidy method.

Thanks

Answer 1

What language?

In python:

import re
regex_fixed = re.escape("business + unit")

In php, use preg_quote()

Answer 2

In Java, use Pattern.quote() or "\\Qprotected part\\E" if you want to do it manually.

Answer 3

Many regex flavors have a utility method that automatically escapes meta characters. Java does this using Pattern.quote(String) and PHP has a similar function: preg_quote(string). Many PCRE implementations also support the \Q and \E escape sequences. \Q will let the regex engine interpret all characters after it as plain literals until the next \E.

Example:

a\Q+*\Eb+

will match the string a+*bbb.

Answer 4

Replace [[\]\^\-\\\/?*+$().|] with \$& (backslash followed by $&, the matched string) with the global flag on.