From 23441bb5a4a0bf50451f56b20e3376a468c71afb Mon Sep 17 00:00:00 2001
From: Yorick Peterse <yorickpeterse@gmail.com>
Date: Thu, 14 Aug 2014 18:17:08 +0200
Subject: [PATCH] Basic support for the XPath node() function.

---
 lib/oga/xpath/evaluator.rb                    | 53 +++++++++++++++++++
 .../xpath/evaluator/functions/node_spec.rb    | 50 +++++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 spec/oga/xpath/evaluator/functions/node_spec.rb

diff --git a/lib/oga/xpath/evaluator.rb b/lib/oga/xpath/evaluator.rb
index 148c79a..dbafa39 100644
--- a/lib/oga/xpath/evaluator.rb
+++ b/lib/oga/xpath/evaluator.rb
@@ -420,6 +420,59 @@ module Oga
         return nodes
       end
 
+      ##
+      # Dispatches function calls to specific handlers.
+      #
+      # @param [Oga::XPath::Node] ast_node
+      # @param [Oga::XML::NodeSet] context
+      # @return [Oga::XML::NodeSet]
+      #
+      def on_call(ast_node, context)
+        name, test = *ast_node
+
+        handler = name.gsub('-', '_')
+
+        return send("on_call_#{handler}", test, context)
+      end
+
+      ##
+      # Processes the `node` function call. The W3 was apparently too lazy to
+      # properly document this function in their official specification. From
+      # Wikipedia:
+      #
+      #     node()
+      #         finds any node at all.
+      #
+      # Based on trial and error this function appears to match the following:
+      #
+      # * elements
+      # * text nodes
+      # * comments
+      # * CDATA nodes
+      #
+      # In Oga this translates to the following two classes:
+      #
+      # * {Oga::XML::Element}
+      # * {Oga::XML::Text}
+      #
+      # @param [Oga::XPath::Node] ast_node
+      # @param [Oga::XML::NodeSet] context
+      # @return [Oga::XML::NodeSet]
+      #
+      def on_call_node(ast_node, context)
+        nodes = XML::NodeSet.new
+
+        context.each do |context_node|
+          context_node.children.each do |child|
+            if child.is_a?(XML::Element) or child.is_a?(XML::Text)
+              nodes << child
+            end
+          end
+        end
+
+        return nodes
+      end
+
       ##
       # Returns a node set containing all the child nodes of the given set of
       # nodes.
diff --git a/spec/oga/xpath/evaluator/functions/node_spec.rb b/spec/oga/xpath/evaluator/functions/node_spec.rb
new file mode 100644
index 0000000..1e9f145
--- /dev/null
+++ b/spec/oga/xpath/evaluator/functions/node_spec.rb
@@ -0,0 +1,50 @@
+require 'spec_helper'
+
+describe Oga::XPath::Evaluator do
+  context 'node function' do
+    before do
+      @document  = parse('<a><b>foo</b></a>')
+      @evaluator = described_class.new(@document)
+    end
+
+    context 'matching elements' do
+      before do
+        @set = @evaluator.evaluate('node()')
+      end
+
+      it_behaves_like :node_set, :length => 1
+
+      example 'return the <a> node' do
+        @set[0].name.should == 'a'
+      end
+    end
+
+    context 'matching nested elements' do
+      before do
+        @set = @evaluator.evaluate('a/node()')
+      end
+
+      it_behaves_like :node_set, :length => 1
+
+      example 'return the <b> node' do
+        @set[0].name.should == 'b'
+      end
+    end
+
+    context 'matching text nodes' do
+      before do
+        @set = @evaluator.evaluate('a/b/node()')
+      end
+
+      it_behaves_like :node_set, :length => 1
+
+      example 'return a Text instance' do
+        @set[0].is_a?(Oga::XML::Text).should == true
+      end
+
+      example 'include the text' do
+        @set[0].text.should == 'foo'
+      end
+    end
+  end
+end