class Rouge::TextAnalyzer

def doctype

Return the contents of the doctype tag if present, nil otherwise. 
def doctype
  return @doctype if instance_variable_defined? :@doctype
  self =~ %r(\A\s*
    (?:<\?.*?\?>\s*)? # possible <?xml...?> tag
    <!DOCTYPE\s+(.+?)>
  )xm
  @doctype = $1
end

def doctype?(type=//)

Check if the doctype matches a given regexp or string 
def doctype?(type=//)
  type === doctype
end

def lexes_cleanly?(lexer)

error tokens.
Return true if the result of lexing with the given lexer contains no 
def lexes_cleanly?(lexer)
  lexer.lex(self) do |(tok, _)|
    return false if tok.name == 'Error'
  end
  true
end

def shebang

Find a shebang. Returns nil if no shebang is present. 
def shebang
  return @shebang if instance_variable_defined? :@shebang
  self =~ /\A\s*#!(.*)$/
  @shebang = $1
end

def shebang?(match)

`#!/bash`, '#!/bin/bash', '#!/usr/bin/env bash', and '#!/bin/bash -x'
This normalizes things so that `text.shebang?('bash')` will detect

Check if the given shebang is present. 
def shebang?(match)
  match = /\b#{match}(\s|$)/
  match === shebang
end