正则表达式，用于将字符串与插值占位符匹配

Question

Suppose I have a string with interpolation placeholder variables:

"The %s fox %s over the lazy %s" 

For use with the % operator (what is it called in this context BTW?) eg:

"The %s fox %s over the lazy %s" % ["quick", "jumps", "dog"]

How would I write a Regex expression that would match any string against this uninterpolated string

"The %s fox %s over the lazy %s"
"The quick fox jumps over the lazy dog"
"The 1 fox 2 over the lazy #@$#"

Answer 1

The easiest is to transform the pattern into regexp, with placeholders changed to capture-anything groups.

strings = [
  "The %s fox %s over the lazy %s",
  "The quick fox jumps over the lazy dog",
  "The quick and agile fox nimbly jumps over the lazy son of a bitch",
  "The quick fox defiantly crawls under the lazy dog"
]

pattern = "The %s fox %s over the lazy %s" 

pattern_re = /^#{Regexp.escape(pattern).gsub(/%s/, '(.*)')}$/
strings.map { |string| pattern_re.match(string) }
# => [
#      #<MatchData "The %s fox %s over the lazy %s" 1:"%s" 2:"%s" 3:"%s">,
#      #<MatchData "The quick fox jumps over the lazy dog" 1:"quick" 2:"jumps" 3:"dog">,
#      #<MatchData "The quick and agile fox nimbly jumps over the lazy son of a bitch" 1:"quick and agile" 2:"nimbly jumps" 3:"son of a bitch">,
#      nil
#    ]