Library to parse ERB files

Question

I am attempting to parse, not evaluate, rails ERB files in a Hpricot/Nokogiri type manner. The files I am attempting to parse contain HTML fragments intermixed with dynamic con

Answer 1

I recently had a similar problem. The approach that I took was to write a small script (erblint.rb) do a string substitution to convert the ERB tags (<% %> and <%= %>) to XML tags, and then parse using Nokogiri.

See the following code to see what I mean:

#!/usr/bin/env ruby
require 'rubygems'
require 'nokogiri'

# This is a simple program that reads in a Ruby ERB file, and parses
# it as an XHTML file. Specifically, it makes a decent attempt at
# converting the ERB tags (<% %> and <%= %>) to XML tags (
# and  respectively.
#
# Once the document has been parsed, it will be validated and any
# error messages will be displayed.
#
# More complex option and error handling is left as an exercise to the user.

abort 'Usage: erb.rb ' if ARGV.empty?

filename = ARGV[0]

begin
  doc = ""
  File.open(filename) do |file|
    puts "\n*** Parsing #{filename} ***\n\n"
    file.read(nil, s = "")

    # Substitute the standard ERB tags to convert them to XML tags
    #   <%= ... %> for  ... 
    #   <% ... %>  for  ... 
    #
    # Note that this won't work for more complex expressions such as:
    #    >link text
    # Of course, this is not great style, anyway...
    s.gsub!(/<%=(.+?)%>/m, '\1')
    s.gsub!(/<%(.+?)%>/m, '\1')
    doc = Nokogiri::XML(s) do |config|
      # put more config options here if required
      # config.strict
    end
  end

  puts doc.to_xhtml(:indent => 2, :encoding => 'UTF-8')
  puts "Huzzah, no errors!" if doc.errors.empty?

  # Otherwise, print each error message
  doc.errors.each { |e| puts "Error at line #{e.line}: #{e}" }
rescue
  puts "Oops! Cannot open #{filename}"
end

I've posted this as a gist on Github: https://gist.github.com/787145