Add rake dump_portable_ast

lib/liquid/ast_to_portable_json.rb

@@ -0,0 +1,27 @@
+require 'yaml'
+require 'json'
+require 'liquid'
+
+module Liquid
+  class ASTToPortableJSON
+    def self.dump(ast)
+      yaml = YAML.dump(ast)
+      yaml.gsub!(/---.*/, '')
+      yaml.gsub!(/!ruby\/object:(.+)\n(\s+)/, "\n\\2class_name: \\1\n\\2")
+
+      bare_hash_ast = YAML.load(yaml)
+      delete_parse_context(bare_hash_ast)
+      JSON.pretty_generate(bare_hash_ast)
+    end
+
+    def self.delete_parse_context(bare_hash_ast)
+      if bare_hash_ast.is_a?(Array)
+        bare_hash_ast.each { |v| delete_parse_context(v) }
+      elsif bare_hash_ast.is_a?(Hash)
+        bare_hash_ast.delete('parse_context')
+        bare_hash_ast.each { |k, v| delete_parse_context(v) }
+      end
+    end
+  end
+end
+