Enable other interpolation styles

Enable `#@instance_var` and `#$global_var` styles of interpolation.

lib/haml/parser.rb

@@ -220,7 +220,7 @@ def process_line(line)
  case line.text[0]
  when DIV_CLASS; push div(line)
  when DIV_ID
- return push plain(line) if line.text[1] == ?{
+ return push plain(line) if %w[{ @ $].include?(line.text[1])
  push div(line)
  when ELEMENT; push tag(line)
  when COMMENT; push comment(line.text[1..-1].lstrip)

lib/haml/util.rb

@@ -175,7 +175,7 @@ def inspect_obj(obj)
  # @return [String] The text remaining in the scanner after all `#{`s have been processed
  def handle_interpolation(str)
  scan = StringScanner.new(str)
- yield scan while scan.scan(/(.*?)(\\*)\#\{/)
+ yield scan while scan.scan(/(.*?)(\\*)\#([\{@$])/)
  scan.rest
  end
 
@@ -224,20 +224,26 @@ def human_indentation(indentation)
  end
 
  def contains_interpolation?(str)
- str.include?('#{')
+ /#[\{$@]/ === str
  end
 
  def unescape_interpolation(str, escape_html = nil)
  res = ''
  rest = Haml::Util.handle_interpolation str.dump do |scan|
  escapes = (scan[2].size - 1) / 2
+ char = scan[3] # '{', '@' or '$'
  res << scan.matched[0...-3 - escapes]
  if escapes % 2 == 1
- res << '#{'
+ res << "\##{char}"
  else
- content = eval('"' + balance(scan, ?{, ?}, 1)[0][0...-1] + '"')
+ interpolated = if char == '{'
+ balance(scan, ?{, ?}, 1)[0][0...-1]
+ else
+ scan.scan(/\w+/)
+ end
+ content = eval('"' + interpolated + '"')
  content = "Haml::Helpers.html_escape((#{content}))" if escape_html
- res << '#{' + content + "}"# Use eval to get rid of string escapes
+ res << "\##{char}#{content}#{"}" if char == '{'}"
  end
  end
  res + rest