Parse prefix

[electrum]

I'd like to parse a date from the start of a string, ignoring invalid characters after a valid date. For example, using mmm d, yyyy, parse the following:

March 21, 2010 is a Monday

The extra characters " is a Monday" would be ignored.

[adzap]

This is a tricky one. It should be possible to create a custom format which allows other text around it. But you might want to look at Chronic or Nickel https://github.com/lzell/nickel.

The limitation for Timeliness is that it uses regexps and removes some regex specific characters from a format before compiling the string into a regexp. This makes it a little tricky to navigate around this to allow open ended strings with junk in it.

Timeliness is more about control and speed than freedom to parse any string.

[electrum]

Thanks for the link to Nickel -- I hadn't seen that one. What I ended up doing was combining regexes with strptime:

  '\d{1,2}/\d{1,2}/\d{2}' => '%m/%d/%y',
  '\d{1,2}/\d{1,2}/\d{4}' => '%m/%d/%Y',
  '[a-z]{3,} \d{1,2}, \d{4}' => '%b %d, %Y',

You need the regexes because strptime will incorrectly parse strings that don't match the format:

ruby > Date.strptime('01/02/03', '%m/%d/%Y')
 => #<Date: 0003-01-02 (3444309/2,0,2299161)> 
ruby > Date.strptime('01/02/2003', '%m/%d/%y')
 => #<Date: 2020-01-02 (4917701/2,0,2299161)> 

Fortunately, it's laxness causes it to ignore the extra junk at the end.

[adzap]

I played with Timeliness more to get this to work and found this is possible

Timeliness.parse('March 12, 2011 asdf', :type => :date, :format => 'mmm d, yyyy [a-zA-Z0-9 ]*')

It's very fragile however. You would need to add more characters which may be included in the string.