(#127) Allow escaping %{...} in hiera data so that hiera does not try to...

lib/hiera/interpolate.rb

@@ -3,15 +3,34 @@
 
 class Hiera::Interpolate
   class << self
-    INTERPOLATION = /%\{([^\}]*)\}/
+    INTERPOLATION = /%+\{([^\}]*)\}/
     METHOD_INTERPOLATION = /%\{(scope|hiera)\(['"]([^"']*)["']\)\}/
 
     def interpolate(data, scope, extra_data)
       if data.is_a?(String)
         # Wrapping do_interpolation in a gsub block ensures we process
         # each interpolation site in isolation using separate recursion guards.
         data.gsub(INTERPOLATION) do |match|
-          do_interpolation(match, Hiera::RecursiveGuard.new, scope, extra_data)
+          #Allow escaping of %{} to support litteral %{some_text} in hiera data.
+          #Should support escaping of escapes so full list of scenarios looks like:
+          #    %{var}      : 'value of var'
+          #   %%{literal}  : '%{literal}'
+          #  %%%{var}      : '%value of var'
+          # %%%%{literal}  : '%%{literal}'
+
+          percents = match.match(/^(%+)/)[1]
+          if percents.length.even?
+            match.gsub(/%%/,'%')
+          else
+            #Remove a % that represents the interpolation from percents
+            #Of the remaining %'s sub each '%%' for '%' ('%%' is an escaped '%')
+            #Remove all but one % from the match to feed into do_intepolation
+            #add the percents (the escaped % signs back on so %%%{var} becomes %value
+            percents.chop!
+            percents.gsub!(/%%/,'%')
+            match.sub!(/^%+/,'%')
+            percents + do_interpolation(match, Hiera::RecursiveGuard.new, scope, extra_data).to_s
+          end
         end
       else
         data

spec/unit/backend_spec.rb

@@ -5,11 +5,25 @@ class Hiera
   describe Backend do
     describe "#datadir" do
       it "interpolates any values in the configured value" do
-        Config.load({:rspec => {:datadir => "/tmp/%{interpolate}"}})
-
-        dir = Backend.datadir(:rspec, { "interpolate" => "my_data" })
+        interpolation_tests = {
+          :test1 => '%{interpolate}',
+          :test2 => '%%{interpolate}',
+          :test3 => '%%%{interpolate}',
+          :test4 => '%%%%{interpolate}',
+        }
+
+        results = {}
+        interpolation_tests.each do |test,value|
+          puts "testing #{test} #{value}"
+          Config.load({:rspec => {:datadir => "/tmp/#{value}"}})
+          results[test] = Backend.datadir(:rspec, { "interpolate" => "variable" })
+        end
 
-        dir.should == "/tmp/my_data"
+        puts "Results: #{results}"
+        results[:test1].should == "/tmp/variable"
+        results[:test2].should == "/tmp/%{interpolate}"
+        results[:test3].should == "/tmp/%variable"
+        results[:test4].should == "/tmp/%%{interpolate}"
       end
 
       it "defaults to a directory in var" do