Question

I have some content like this:

    author = "Marjan Mernik  and Viljem Zumer",
    title = "Implementation of multiple attribute grammar inheritance in the tool LISA",
    year = 1999

    author = "Manfred Broy and Martin Wirsing",
    title = "Generalized
             Heterogeneous Algebras and
             Partial Interpretations",
    year = 1983

    author = "Ikuo Nakata and Masataka Sassa",
    title = "L-Attributed LL(1)-Grammars are
             LR-Attributed",
    journal = "Information Processing Letters"

And I need to catch everything between double quotes for title. My first try was this:

^(" "|\t)+"title"" "*=" "*"\"".+"\","

Which catches the first example, but not the other two. The other have multiple lines and that’s the problem. I though about changing to something with \n somewhere to allow multiple lines, like this:

^(" "|\t)+"title"" "*=" "*"\""(.|\n)+"\","

But this doesn’t help, instead, it catches everything.

Than I though, “what I want is between double quotes, what if I catch everything until I find another " followed by ,? This way I could know if I was at the end of the title or not, no matter the number of lines, like this:

^(" "|\t)+"title"" "*=" "*"\""[^"\""]+","

But this has another problem… The example above doesn’t have it, but the double quote symbol (") can be in between the title declaration. For instance:

title = "aaaaaaa \"X bbbbbb",

And yes, it will always be preceded by a backslash (\).

Any suggestions to fix this regexp?

Answer 1

The classical regex to match strings in double quotes is:

\"([^\"]|\\.)*\"

In your case, you’ll want something like this:

"title"\ *=\ *\"([^\"]|\\.)*\"

PS: IMHO, you’re putting too many quotes in your regexes, it’s hard to read.