Question

I’m looking for a SimpleGrepSedPerlOrPythonOneLiner that outputs all quotations in a text.

---

Example 1:

echo “HAL,” noted Frank, “said that everything was going extremely well.” | SimpleGrepSedPerlOrPythonOneLiner 

stdout:

'HAL,' 'said that everything was going extremely well.” 

---

Example 2:

cat MicrosoftWindowsXPEula.txt | SimpleGrepSedPerlOrPythonOneLiner 

stdout:

'EULA' 'Software' 'Workstation Computer' 'Device' 'DRM' 

etc.

(link to the corresponding text).

Answer 1

I like this:

perl -ne 'print '$_\n' foreach /'((?>[^'\\]|\\+[^']|\\(?:\\\\)*')*)'/g;' 

It’s a little verbose, but it handles escaped quotes and backtracking a lot better than the simplest implementation. What it’s saying is:

my $re = qr{    '               # Begin it with literal quote    (       (?>           # prevent backtracking once the alternation has been                    # satisfied. It either agrees or it does not. This expression                    # only needs one direction, or we fail out of the branch           [^'\\]    # a character that is not a dquote or a backslash      |   \\+       # OR if a backslash, then any number of backslashes followed by           [^']      # something that is not a quote      |   \\        # OR again a backslash          (?>\\\\)* # followed by any number of *pairs* of backslashes (as units)          '         # and a quote      )*            # any number of *set* qualifying phrases   )                # all batched up together   '                # Ended by a literal quote }x; 

If you don’t need that much power–say it’s only likely to be dialog and not structured quotes, then

/'([^']*)'/  

probably works about as well as anything else.