class String # If you pass a single integer, returns a substring of one character at that # position. The first character of the string is at position 0, the next at # position 1, and so on. If a range is supplied, a substring containing # characters at offsets given by the range is returned. In both cases, if an # offset is negative, it is counted from the end of the string. Returns +nil+ # if the initial offset falls outside the string. Returns an empty string if # the beginning of the range is greater than the end of the string. # # str = "hello" # str.at(0) # => "h" # str.at(1..3) # => "ell" # str.at(-2) # => "l" # str.at(-2..-1) # => "lo" # str.at(5) # => nil # str.at(5..-1) # => "" # # If a Regexp is given, the matching portion of the string is returned. # If a String is given, that given string is returned if it occurs in # the string. In both cases, +nil+ is returned if there is no match. # # str = "hello" # str.at(/lo/) # => "lo" # str.at(/ol/) # => nil # str.at("lo") # => "lo" # str.at("ol") # => nil def at(position) self[position] end # Returns a substring from the given position to the end of the string. # If the position is negative, it is counted from the end of the string. # # str = "hello" # str.from(0) # => "hello" # str.from(3) # => "lo" # str.from(-2) # => "lo" # # You can mix it with +to+ method and do fun things like: # # str = "hello" # str.from(0).to(-1) # => "hello" # str.from(1).to(-2) # => "ell" def from(position) self[position..-1] end # Returns a substring from the beginning of the string to the given position. # If the position is negative, it is counted from the end of the string. # # str = "hello" # str.to(0) # => "h" # str.to(3) # => "hell" # str.to(-2) # => "hell" # # You can mix it with +from+ method and do fun things like: # # str = "hello" # str.from(0).to(-1) # => "hello" # str.from(1).to(-2) # => "ell" def to(position) self[0..position] end # Returns the first character. If a limit is supplied, returns a substring # from the beginning of the string until it reaches the limit value. If the # given limit is greater than or equal to the string length, returns a copy of self. # # str = "hello" # str.first # => "h" # str.first(1) # => "h" # str.first(2) # => "he" # str.first(0) # => "" # str.first(6) # => "hello" def first(limit = 1) if limit == 0 "" elsif limit >= size dup else to(limit - 1) end end # Returns the last character of the string. If a limit is supplied, returns a substring # from the end of the string until it reaches the limit value (counting backwards). If # the given limit is greater than or equal to the string length, returns a copy of self. # # str = "hello" # str.last # => "o" # str.last(1) # => "o" # str.last(2) # => "lo" # str.last(0) # => "" # str.last(6) # => "hello" def last(limit = 1) if limit == 0 "" elsif limit >= size dup else from(-limit) end end end