Ruby/Development/Regexps

hamlet = "The slings and arrows of outrageous fortune"
puts hamlet.scan(/\w+/)

opening = "man men woman women"
p opening.grep(/\Aen in/)

color = "color colour"
color.grep(/colou?r/) # => ["I think that colour is just right for you office."]

phone = "(555)123-4567"
 
phone.grep(/[\(\d{3}\)]?\d{3}-\d{4}/)# => ["(555)123-4567"]

phone = "(555)123-4567"
 
phone.grep(/[\(\d+\)]?\d+-\d+/) # => ["(555)123-4567"]

phone = "(555)123-4567"
phone.grep(/[\(\d\d\d\)]?\d\d\d-\d\d\d\d/) # => ["(555)123-4567"]

opening = "man men woman women"
p opening.grep(/e n,\z/)

opening = "man men woman women"
 
p opening.grep(/m[ae]n/)

opening = "man men woman women"
p opening.grep(/m(e|a)n/)

opening = "this is a test \n this is a test,\n"
p opening.grep(/test/)

opening = "man men woman women"
 
p opening.grep(/men|man/)

opening = "man men woman women"
p opening.grep(/m a,$/)

opening = "man men woman women"
p opening.grep(/^en in/)

class Regexp
  def Regexp.is_valid?(str)
    begin
      compile(str)
      valid = true
    rescue RegexpError
      valid = false
    end
  end
end
Regexp.is_valid? "The horror!"                     # => true
Regexp.is_valid? "The)horror!"                     # => false

line = "A horse! a horse! my kingdom for a horse!"
line[/horse!$/] # => "horse!"

 line = "abc"
  if line =~ /Perl|Python/
    puts "Scripting language mentioned: #{line}"
  end

/\d\d:\d\d:\d\d/     # a time such as 12:34:56

re = /(\d+):(\d+)/ 
md1 = re.match("Time: 12:34am") 
md2 = re.match("Time: 10:30pm") 
p [ $1, $2 ]
$~ =md1 
p [ $1, $2 ]

  /Perl Python/        # Perl, a space, and Python

  /Perl +Python/       # Perl, one or more spaces, and Python

/Perl\s+Python/      # Perl, whitespace characters, then Python

 
  /Perl.*Python/       # Perl, zero or more other chars, then Python

  /Perl *Python/       # Perl, zero or more spaces, and Python

/Ruby (Perl|Python)/ # Ruby, a space, and either Perl or Python

A combination of the special characters, enclosed by a pair of slashes (//), makes up a regular expression pattern. 
 
^        Matches the beginning of a line
$        Matches the end of a line
\w       Matches a word character
[...]    Matches any character in the brackets
[^...]   Matches any characters not in the brackets
*        Matches zero or more occurrences of the previous regexp
+        Matches one or more occurrences of the previous regexp
?        Matches zero or one occurrences of the previous regexp

line = "Perl or Python"
puts line.gsub(/Perl|Python/, "Ruby")

line = "A horse! a horse! my kingdom for a horse!"
line[/^A horse/, 0] # => "A horse"

line = "abc"
line.sub(/Perl/, "Ruby")    # replace first "Perl" with "Ruby"
line.gsub(/Python/, "Ruby") # replace every "Python" with "Ruby"

# If unsuccessful,the method returns nil.
# On success,it returns an instance of class MatchData. 
# And that MatchData object gives you access to all available in formation.
re = /cat/ 
puts re.class # Regexp 
 
re = /(\d+):(\d+)/ # match a time hh:mm 
md = re.match("Time: 12:34am") 
puts md.class 
puts md[0] 
puts md[1] 
puts md[2] 
puts md.pre_match 
puts md.post_match