Enable matching with `Node#deconstruct` (#31)

lib/ast/node.rb

@@ -229,9 +229,9 @@ module AST
     def to_ast
       self
     end
-    
+
     # Converts `self` to an Array where the first element is the type as a Symbol,
-    # and subsequent elements are the same representation of its children. 
+    # and subsequent elements are the same representation of its children.
     #
     # @return [Array<Symbol, [...Array]>]
     def to_sexp_array
@@ -246,6 +246,14 @@ module AST
       [type, *children_sexp_arrs]
     end
 
+    # Enables matching for Node, where type is the first element
+    # and the children are remaining items.
+    #
+    # @return [Array]
+    def deconstruct
+      [type, *children]
+    end
+
     protected
 
     # Returns `@type` with all underscores replaced by dashes. This allows

test/test_ast.rb

@@ -102,7 +102,7 @@ describe AST::Node do
   it 'should return self in to_ast' do
     @node.to_ast.should.be.identical_to @node
   end
-  
+
   it 'should produce to_sexp_array correctly' do
     AST::Node.new(:a, [ :sym, [ 1, 2 ] ]).to_sexp_array.should.equal [:a, :sym, [1, 2]]
     AST::Node.new(:a, [ :sym,
@@ -175,6 +175,22 @@ describe AST::Node do
   rescue SyntaxError
     # Running on 1.8, ignore.
   end
+
+  begin
+    eval <<-CODE
+    it 'should be matchable' do
+      baz = s(:baz, s(:bar, 1), 2)
+      r = case baz
+      in [:baz, [:bar, val], Integer] then val
+      else
+        :no_match
+      end
+      r.should.equal 1
+    end
+    CODE
+  rescue SyntaxError
+    # Running on < 2.7, ignore.
+  end
 end
 
 describe AST::Processor do