diff --git a/lib/jsduck/ast_node.rb b/lib/jsduck/ast_node.rb
new file mode 100644
index 0000000000000000000000000000000000000000..b0b5e9f39570fb894d52362e9fc8851fa2a92f36
--- /dev/null
+++ b/lib/jsduck/ast_node.rb
@@ -0,0 +1,103 @@
+require "jsduck/serializer"
+require "jsduck/evaluator"
+require "jsduck/ext_patterns"
+
+module JsDuck
+
+  # Wraps around AST node returned from Esprima, providing methods for
+  # investigating it.
+  class AstNode
+    # Initialized with a AST Hash from Esprima.
+    def initialize(node)
+      @node = node
+    end
+
+    def expression?
+      @node["type"] == "ExpressionStatement"
+    end
+
+    def call?
+      @node["type"] == "CallExpression"
+    end
+
+    def assignment?(ast)
+      @node["type"] == "AssignmentExpression"
+    end
+
+    def function?(ast)
+      @node["type"] == "FunctionDeclaration" || @node["type"] == "FunctionExpression" || empty_fn?
+    end
+
+    def empty_fn?(ast)
+      @node["type"] == "MemberExpression" && ext_pattern?("Ext.emptyFn")
+    end
+
+    def ext_pattern?(pattern)
+      @ext_patterns.matches?(pattern, to_s)
+    end
+
+    def fire_event?(ast)
+      call? && child("callee").to_s == "this.fireEvent"
+    end
+
+    def var?(ast)
+      @node["type"] == "VariableDeclaration"
+    end
+
+    def property?(ast)
+      @node["type"] == "Property"
+    end
+
+    def ident?(ast)
+      @node["type"] == "Identifier"
+    end
+
+    def string?(ast)
+      @node["type"] == "Literal" && @node["value"].is_a?(String)
+    end
+
+    def object?(ast)
+      @node["type"] == "ObjectExpression"
+    end
+
+    # Returns a child AST node as AstNode class.
+    def child(name)
+      AstNode.new(@node[name])
+    end
+
+    # Serializes the node into string
+    def to_s
+      Serializer.new.to_s(@node)
+    end
+
+    # Evaluates the node into basic JavaScript value.
+    def to_value
+      begin
+        Evaluator.new.to_value(@node)
+      rescue
+        nil
+      end
+    end
+
+    def value_type
+      v = to_value
+      if v.is_a?(String)
+        "String"
+      elsif v.is_a?(Numeric)
+        "Number"
+      elsif v.is_a?(TrueClass) || v.is_a?(FalseClass)
+        "Boolean"
+      elsif v.is_a?(Array)
+        "Array"
+      elsif v.is_a?(Hash)
+        "Object"
+      elsif v == :regexp
+        "RegExp"
+      else
+        nil
+      end
+    end
+
+  end
+
+end