.try在ruby中使用正则表达式

Question

I have a method which returns the title of a page. The title can return string containing Episodes info and without episodes info. For eg: "Friends Can chat" and "Episode 12 Hollow man" I need to use regular expression on the final string and return it.

title = row.at("h3")
           .try(:children)
           .try(:first)
           .try(:text)
           .try(:strip)
           .try(:[], /(Episode \d+ [–-]\s*)(.*)/,2)

Here I get Hollow man as title since it contains episodes info and the regular expression matches here. But in the first case it returns nil, since "Friends can chat" does not have episode info and hence it would return nil on matching with regex.

So how can I return it efficiently. I can use like

title = row.at("h3")
           .try(:children)
           .try(:first)
           .try(:text)
           .try(:strip)

title = title.try(:[], /(Episode \d+ [–-]\s*)(.*)/,2) \
     if title && title.try(:[], /(Episode \d+ [–-]\s*)(.*)/,2)

Any other way I can return it efficiently.

Answer 1

You might modify your regular expression to make “Episode” string not mandatory:

# /(Episode \d+ [–-]\s*)(.*)/
/(Episode\s+\d+\s+[–-]?\s*)?(.*))/

That will match both:

a = ["Friends Can chat", "Episode 12 Hollow man"]
a.map { |t| 
  #                  ⇓ No episode?—no worry!
  /(Episode\s+\d+\s*)?(.*)/ =~ t
  ($~[1] ? $~[1] : 'NO EPISODE ') + $~[2] 
}
# [
#  [0] "NO EPISODE Friends Can chat",
#  [1] "Episode 12 Hollow man"
# ]

Hope it helps.