转义tr1 :: regex的正则表达式特殊字符

Question

I need to embed user-input in my regular expression , so it needs to be escaped for any regex special characters, and I don't know in advance what the string will be.

It would be something like

string pattern = "\\d+ " + myEscapeFunction(userData);

Which special characters do I need to escape? Or is there an equivalent function to Qt's QRegExp::escape ?

Answer 1

The list of characters that you have to escape depends on which of the various regular expression grammars you're using. If you're using the default ECMAScript , it looks like the list in the QRegExp::escape documentation is a good place to start. It says:

The special characters are $, (,), *, +, ., ?, [, ,], ^, {, | and }.

That list leaves out \\ for some reason.

But it's slightly more complicated than that, because inside square brackets, none of the characters except \\ and ] are special, and \\] has to stay unescaped.

Further, a ? that comes right after a ( is not special. For example, in (?=x) the ? should not be escaped.

I think that's pretty much it, but I haven't put enough time into this to be sure.