1 files changed, 51 insertions, 0 deletions
diff --git a/railties/guides/rails_guides/indexer.rb b/railties/guides/rails_guides/indexer.rb
new file mode 100644
index 0000000000..52809829e2
--- /dev/null
+++ b/railties/guides/rails_guides/indexer.rb
@@ -0,0 +1,51 @@
+module RailsGuides
+  class Indexer
+    attr_reader :body, :result, :level_hash
+
+    def initialize(body)
+      @body = body
+      @result = @body.dup
+    end
+
+    def index
+      @level_hash = process(body)
+    end
+
+    private
+
+    def process(string, current_level= 3, counters = [1])
+      s = StringScanner.new(string)
+
+      level_hash = ActiveSupport::OrderedHash.new
+
+      while !s.eos?
+        s.match?(/\h[0-9]\..*$/)
+        if matched = s.matched
+          matched =~ /\h([0-9])\.(.*)$/
+          level, title = $1.to_i, $2
+
+          if level < current_level
+            # This is needed. Go figure.
+            return level_hash
+          elsif level == current_level
+            index = counters.join(".")
+            bookmark = '#' + title.gsub(/[^a-z0-9\-_\+]+/i, '').underscore.dasherize
+
+            raise "Parsing Fail" unless @result.sub!(matched, "h#{level}(#{bookmark}). #{index}#{title}")
+
+            # Recurse
+            counters << 1
+            level_hash[title.strip] = process(s.post_match, current_level + 1, counters)
+            counters.pop
+
+            # Increment the current level
+            last = counters.pop
+            counters << last + 1
+          end
+        end
+        s.getch
+      end
+      level_hash
+    end
+  end
+end