XPath support for processing instructions.

lib/oga/xpath/evaluator.rb

@@ -491,6 +491,24 @@ module Oga
         return nodes
       end
 
+      ##
+      # Processes the `processing-instruction()` type test. This matches only
+      # processing-instruction nodes.
+      #
+      # @param [Oga::XPath::Node] ast_node
+      # @param [Oga::XML::NodeSet] context
+      # @return [Oga::XML::NodeSet]
+      #
+      def on_type_test_processing_instruction(ast_node, context)
+        nodes = XML::NodeSet.new
+
+        context.each do |node|
+          nodes << node if node.is_a?(XML::ProcessingInstruction)
+        end
+
+        return nodes
+      end
+
       ##
       # Returns a node set containing all the child nodes of the given set of
       # nodes.

spec/oga/xpath/evaluator/type_tests/comment_spec.rb

@@ -7,7 +7,7 @@ describe Oga::XPath::Evaluator do
       @evaluator = described_class.new(@document)
     end
 
-    context 'matching text nodes' do
+    context 'matching comment nodes' do
       before do
         @set = @evaluator.evaluate('a/comment()')
       end
@@ -23,7 +23,7 @@ describe Oga::XPath::Evaluator do
       end
     end
 
-    context 'matching nested text nodes' do
+    context 'matching nested comment nodes' do
       before do
         @set = @evaluator.evaluate('a/b/comment()')
       end

spec/oga/xpath/evaluator/type_tests/processing_instruction_spec.rb

@@ -0,0 +1,42 @@
+require 'spec_helper'
+
+describe Oga::XPath::Evaluator do
+  context 'processing-instruction() tests' do
+    before do
+      @document  = parse('<a><?a foo ?><b><?b bar ?></b></a>')
+      @evaluator = described_class.new(@document)
+    end
+
+    context 'matching processing instruction nodes' do
+      before do
+        @set = @evaluator.evaluate('a/processing-instruction()')
+      end
+
+      it_behaves_like :node_set, :length => 1
+
+      example 'return a ProcessingInstruction instance' do
+        @set[0].is_a?(Oga::XML::ProcessingInstruction).should == true
+      end
+
+      example 'return the "foo" node' do
+        @set[0].text.should == ' foo '
+      end
+    end
+
+    context 'matching nested processing instruction nodes' do
+      before do
+        @set = @evaluator.evaluate('a/b/processing-instruction()')
+      end
+
+      it_behaves_like :node_set, :length => 1
+
+      example 'return a ProcessingInstruction instance' do
+        @set[0].is_a?(Oga::XML::ProcessingInstruction).should == true
+      end
+
+      example 'return the "bar" node' do
+        @set[0].text.should == ' bar '
+      end
+    end
+  end
+end