From d2f991538dc2c9ec771249605862d0dc5bbf3a88 Mon Sep 17 00:00:00 2001
From: Yorick Peterse <yorickpeterse@gmail.com>
Date: Wed, 27 Aug 2014 09:37:28 +0200
Subject: [PATCH] Support for the XPath true()/false() functions.

---
 lib/oga/xpath/evaluator.rb                   | 24 ++++++++++++++++++++
 spec/oga/xpath/evaluator/calls/false_spec.rb | 13 +++++++++++
 spec/oga/xpath/evaluator/calls/true_spec.rb  | 13 +++++++++++
 3 files changed, 50 insertions(+)
 create mode 100644 spec/oga/xpath/evaluator/calls/false_spec.rb
 create mode 100644 spec/oga/xpath/evaluator/calls/true_spec.rb

diff --git a/lib/oga/xpath/evaluator.rb b/lib/oga/xpath/evaluator.rb
index 8fa6a84..f999a05 100644
--- a/lib/oga/xpath/evaluator.rb
+++ b/lib/oga/xpath/evaluator.rb
@@ -1074,6 +1074,30 @@ module Oga
         return !on_call_boolean(context, expression)
       end
 
+      ##
+      # Processes the `true()` function call.
+      #
+      # This function simply returns the boolean `true`.
+      #
+      # @param [Oga::XPath::NodeSet] context
+      # @return [TrueClass]
+      #
+      def on_call_true(context)
+        return true
+      end
+
+      ##
+      # Processes the `false()` function call.
+      #
+      # This function simply returns the boolean `false`.
+      #
+      # @param [Oga::XPath::NodeSet] context
+      # @return [FalseClass]
+      #
+      def on_call_false(context)
+        return false
+      end
+
       ##
       # Processes an `(int)` node.
       #
diff --git a/spec/oga/xpath/evaluator/calls/false_spec.rb b/spec/oga/xpath/evaluator/calls/false_spec.rb
new file mode 100644
index 0000000..4403d0d
--- /dev/null
+++ b/spec/oga/xpath/evaluator/calls/false_spec.rb
@@ -0,0 +1,13 @@
+require 'spec_helper'
+
+describe Oga::XPath::Evaluator do
+  context 'false() function' do
+    before do
+      @evaluator = described_class.new(parse(''))
+    end
+
+    example 'return false' do
+      @evaluator.evaluate('false()').should == false
+    end
+  end
+end
diff --git a/spec/oga/xpath/evaluator/calls/true_spec.rb b/spec/oga/xpath/evaluator/calls/true_spec.rb
new file mode 100644
index 0000000..5d90fd4
--- /dev/null
+++ b/spec/oga/xpath/evaluator/calls/true_spec.rb
@@ -0,0 +1,13 @@
+require 'spec_helper'
+
+describe Oga::XPath::Evaluator do
+  context 'true() function' do
+    before do
+      @evaluator = described_class.new(parse(''))
+    end
+
+    example 'return true' do
+      @evaluator.evaluate('true()').should == true
+    end
+  end
+end