From 78c8cd132394cbd05171a72ee011814d8a1f009e Mon Sep 17 00:00:00 2001
From: Yorick Peterse <yorickpeterse@gmail.com>
Date: Thu, 28 Aug 2014 23:05:12 +0200
Subject: [PATCH] Support for the XPath "div" operator.

---
 lib/oga/xpath/evaluator.rb                    | 16 +++++++++
 .../oga/xpath/evaluator/operators/div_spec.rb | 34 +++++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 spec/oga/xpath/evaluator/operators/div_spec.rb

diff --git a/lib/oga/xpath/evaluator.rb b/lib/oga/xpath/evaluator.rb
index ce491dc..6a46ddf 100644
--- a/lib/oga/xpath/evaluator.rb
+++ b/lib/oga/xpath/evaluator.rb
@@ -642,6 +642,22 @@ module Oga
         return on_call_number(context, left) + on_call_number(context, right)
       end
 
+      ##
+      # Processes the `div` operator.
+      #
+      # This operator converts the left and right expressions to numbers and
+      # divides the left number with the right number.
+      #
+      # @param [Oga::XPath::Node] ast_node
+      # @param [Oga::XML::NodeSet] context
+      # @return [Float]
+      #
+      def on_div(ast_node, context)
+        left, right = *ast_node
+
+        return on_call_number(context, left) / on_call_number(context, right)
+      end
+
       ##
       # Delegates function calls to specific handlers.
       #
diff --git a/spec/oga/xpath/evaluator/operators/div_spec.rb b/spec/oga/xpath/evaluator/operators/div_spec.rb
new file mode 100644
index 0000000..91d2d07
--- /dev/null
+++ b/spec/oga/xpath/evaluator/operators/div_spec.rb
@@ -0,0 +1,34 @@
+require 'spec_helper'
+
+describe Oga::XPath::Evaluator do
+  context 'div operator' do
+    before do
+      @document  = parse('<root><a>1</a><b>2</b></root>')
+      @evaluator = described_class.new(@document)
+    end
+
+    example 'divide two numbers' do
+      @evaluator.evaluate('1 div 2').should == 0.5
+    end
+
+    example 'divide a number and a string' do
+      @evaluator.evaluate('1 div "2"').should == 0.5
+    end
+
+    example 'divide two strings' do
+      @evaluator.evaluate('"1" div "2"').should == 0.5
+    end
+
+    example 'divide a number and a node set' do
+      @evaluator.evaluate('root/a div 2').should == 0.5
+    end
+
+    example 'divide two node sets' do
+      @evaluator.evaluate('root/a div root/b').should == 0.5
+    end
+
+    example 'return NaN when trying to divide invalid values' do
+      @evaluator.evaluate('"" div 1').should be_nan
+    end
+  end
+end