perl - 如何提取文本中的所有引文？

Question

我正在寻找一个 SimpleGrepSedPerlOrPythonOneLiner 来输出文本中的所有引号。

示例 1:

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

标准输出:

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

示例 2:

cat MicrosoftWindowsXPEula.txt | SimpleGrepSedPerlOrPythonOneLiner

标准输出:

"EULA"
"Software"
"Workstation Computer"
"Device"
"DRM"

等等。

( link to the corresponding text )。

Answer 1

我喜欢这个:

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

它有点冗长，但它处理转义引号和回溯比最简单的实现要好得多。它的意思是:

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;

如果你不需要那么大的力量——比如说它可能只是对话而不是结构化的引号，那么

/"([^"]*)"/ 

可能和其他任何东西一样有效。