class Roadie::Selector

anywhere a String is expected.
Selectors can be coerced into Strings, so they should be transparent to use
questions about them.
This class can also calculate specificity for the selector and answer a few
represented as two instances of this class.
“Selectors” such as “strong, em” are actually two selectors and should be
p:nth-of-child(4n+1) .important a img
input::placeholder
a:hover
body
A selector is a domain object for a CSS selector, such as:
@api private

def ==(other)

representations are equal.
{Selector}s are equal to other {Selector}s if, and only if, their string 
def ==(other)
  if other.is_a?(self.class)
    other.selector == selector
  else
    super
  end
end

def at_rule? 

def at_rule?
  selector[0, 1] == '@'
end

def initialize(selector, specificity = nil) 

def initialize(selector, specificity = nil)
  @selector = selector.to_s.strip
  @specificity = specificity
end

def inlinable?

We cannot inline styles that appear inside "@" constructs, like +@keyframes+.

(like +::placeholder+, +::before+) or a pseudo function (like +:active+).
It's impossible to inline properties that applies to a pseudo element
Returns whenever or not a selector can be inlined. 
def inlinable?
  !(pseudo_element? || at_rule? || pseudo_function?)
end

def inspect() selector.inspect end 

def inspect() selector.inspect end

def pseudo_element? 

def pseudo_element?
  selector.include? '::'
end

def pseudo_function? 

def pseudo_function?
  BAD_PSEUDO_FUNCTIONS.any? { |bad| selector.include?(bad) }
end

def specificity

Returns the specificity of the selector, calculating it if needed. 
def specificity
  @specificity ||= CssParser.calculate_specificity selector
end

def to_s() selector end 

def to_s() selector end

def to_str() to_s end 

def to_str() to_s end