erb_parser.rb

require 'erb_parser'

class Collector
  def initialize
    @line = 1
    @crlf = nil
  end

  def collect(t)
    result = ErbParser.parse(t)
    result.treetop_ast.elements.map do |node|
      ast(node)
    end
  end

  def ast(node)
    return next_line(node) if crlf?(node)
    return nil if plain_text?(node)
    return skip_erb_tag(node) if erb_tag?(node)
  end

  def crlf?(node)
    return false unless plain_text?(node)
    return false unless node.text_value == "\n"
    true
  end

  def plain_text?(node)
    node.is_a?(ErbParser::ErbGrammar::Text)
  end

  def erb_tag?(node)
    node.is_a?(ErbParser::ErbGrammar::ErbTag)
  end

  def skip_erb_tag(node)
    elements = node.elements.dup
    elements = elements.drop_while { |n| n.text_value == "=" || n.text_value == "<%" || n.text_value == "" }
    ruby_node = elements.first
    diff_columns = ruby_node.interval.first - (@crlf_columns || 0)
    puts @line
    puts diff_columns
  end

  def next_line(node)
    @line += 1
    @crlf_columns = node.interval.first + 1
  end
end

c = Collector.new
c.collect("Plain text <% 5.times {} %>\n<%= 2 + 3 %><%# Comment %>")