Go中跨越多行的正则表达式[关闭]

Question

Is it possible in Go to break a complex regular expression using multiple lines? It would help a lot to create a more readable code.

For example in Scala, Ruby, JavaScript it is possible to use x flag:

x — Free-spacing and line comments (aka extended mode)

And it allows to write regular expression like:

  TAXON_CONCEPTS2 = /\s+
                     (\(?s\.\s?s\.|
                     \(?s\.\s?l\.|
                     \(?s\.\s?str\.|
                     \(?s\.\s?lat\.|
                    sec\.|sec|near)\b.*$/x

I would like to achieve similar code in Go instead of:

var taxonConceptsRe2 = regexp.MustCompile(`(,\s*|\s+)(\(?s\.\s?s\.|\(?s\.\s?l\.|\(?s\.\s?str\.|\(?s\.\s?lat\.).*$`)

Answer 1

You have a few options to improve readability of a regular expression like this.

1. Split the string:

   pattern := `(,\s*|\s+)` +
       `(\(?s\.\s?s\.|` +
       `\(?s\.\s?l\.|` +
       `\(?s\.\s?str\.|` +
       `\(?s\.\s?lat\.).*$`
   

2. Pre-parse the string:

   pattern := strings.Replace(`\s+
                    (\(?s\.\s?s\.|
                    \(?s\.\s?l\.|
                    \(?s\.\s?str\.|
                    \(?s\.\s?lat\.|
                   sec\.|sec|near)\b.*$`,
           "
                   ", "", -1)
   

   If you choose this approach, you'll probably want to build a function to do this for you, and to be a bit more robust.

3. Don't use a regexp. (Obviously not always ideal, but regexes are often very overused, so do this one if it makes sense.)