How to make xpressive engine to act like regular text search

Question

I am using boost xpressive for searching text. I have two search modes.

• text mode (including wild cards * and ?)
• regular expression mode

For both i am using regex_search().

My question is as follows - In text mode, if my search string is [a-z], xpressive searches for character between 'a' to 'z' instead of [a-z].

Is there any flag that can be passed to xpressive so that it searches for [a-z].

I am aware that by giving escape sequence ( for e.g. \[a-z\] ) xpressive will search for [a-z].