Question

I’d like to convert a datetime format string like "%m/%d/%y %H:%M" into a regular expression. I won’t know what is in the format string, and I don’t have to handle every case, so I’ve been trying to just gsub into the string.

DATEFORMAT = "%m/%d/%y %H:%M"

def date_format_to_regex
  format = DATEFORMAT
  format = format.gsub(/\//,'\/')
  format = format.gsub(/%[ymdCHI]/,'[[:digit:]]{2}') #two digits
  format = format.gsub(/%[YMS]/,'[[:digit:]]{4}')    #four digits
  @date_regex = Regexp.new(format)
end

But the output of that screws up a lot of the slashes

"%m/%d/%y %H:%M == (?-mix:[[:digit:]]{2}\\/[[:digit:]]{2}\\/[[:digit:]]{2} [[:digit:]]{2}:[[:digit:]]{4})"

Answer 1

DATEFORMAT = "%m/%d/%y %H:%M"

def date_format_to_regex    
  format = DATEFORMAT.gsub(/%[ymdCHI]/, "\\d{2}").gsub(/%[YMS]/, "\\d{4}")
  @date_regex = Regexp.new(format)
end