From 98527d0d14e51957d9b5593e6598ce2b892439c3 Mon Sep 17 00:00:00 2001
From: John Barker <jebarker@gmail.com>
Date: Sun, 5 Feb 2012 14:30:02 -0500
Subject: [PATCH] Add support for xpath starts-with function

---
 lib/xpath/dsl.rb      |  4 ++++
 lib/xpath/renderer.rb |  5 ++++-
 spec/xpath_spec.rb    | 19 +++++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/lib/xpath/dsl.rb b/lib/xpath/dsl.rb
index 694920b..69a7f8d 100644
--- a/lib/xpath/dsl.rb
+++ b/lib/xpath/dsl.rb
@@ -33,6 +33,10 @@ def contains(expression)
         Expression.new(:contains, current, expression)
       end
 
+      def starts_with(expression)
+        Expression.new(:starts_with, current, expression)
+      end
+
       def text
         Expression.new(:text, current)
       end
diff --git a/lib/xpath/renderer.rb b/lib/xpath/renderer.rb
index 71186dd..6f4367b 100644
--- a/lib/xpath/renderer.rb
+++ b/lib/xpath/renderer.rb
@@ -123,9 +123,12 @@ def contains(current, value)
       "contains(#{current}, #{value})"
     end
 
+    def starts_with(current, value)
+      "starts-with(#{current}, #{value})"
+    end
+
     def and(one, two)
       "(#{one} and #{two})"
-
     end
 
     def or(one, two)
diff --git a/spec/xpath_spec.rb b/spec/xpath_spec.rb
index a271c27..3c0d453 100644
--- a/spec/xpath_spec.rb
+++ b/spec/xpath_spec.rb
@@ -125,6 +125,25 @@ def xpath(predicate=nil, &block)
     end
   end
 
+  describe '#starts_with' do
+    it "should find nodes that begin with the given string" do
+      @results = xpath do |x|
+        x.descendant(:*).where(x.attr(:id).starts_with('foo'))
+      end
+      @results.size.should == 2
+      @results[0][:id].should == "foo"
+      @results[1][:id].should == "fooDiv"
+    end
+
+    it "should find nodes that contain the given expression" do
+      @results = xpath do |x|
+        expression = x.anywhere(:div).where(x.attr(:title) == 'fooDiv').attr(:id)
+        x.descendant(:div).where(x.attr(:title).starts_with(expression))
+      end
+      @results[0][:id].should == "foo"
+    end
+  end
+
   describe '#text' do
     it "should select a node's text" do
       @results = xpath { |x| x.descendant(:p).where(x.text == 'Bax') }