xpath: Fix wrong position with nested path (#122)

## Why? Fixed incorrect calculation of position in node set. Fix GH-25 Reported by jcavalieri. Thanks!!!

Author: naitoh

lib/rexml/xpath_parser.rb

@@ -590,6 +590,7 @@ def filter_nodeset(nodeset)
 
  def evaluate_predicate(expression, nodesets)
  enter(:predicate, expression, nodesets) if @debug
+ new_nodeset_count = 0
  new_nodesets = nodesets.collect do |nodeset|
  new_nodeset = []
  subcontext = { :size => nodeset.size }
@@ -606,17 +607,20 @@ def evaluate_predicate(expression, nodesets)
  result = result[0] if result.kind_of? Array and result.length == 1
  if result.kind_of? Numeric
  if result == node.position
- new_nodeset << XPathNode.new(node, position: new_nodeset.size + 1)
+ new_nodeset_count += 1
+ new_nodeset << XPathNode.new(node, position: new_nodeset_count)
  end
  elsif result.instance_of? Array
  if result.size > 0 and result.inject(false) {|k,s| s or k}
  if result.size > 0
- new_nodeset << XPathNode.new(node, position: new_nodeset.size + 1)
+ new_nodeset_count += 1
+ new_nodeset << XPathNode.new(node, position: new_nodeset_count)
  end
  end
  else
  if result
- new_nodeset << XPathNode.new(node, position: new_nodeset.size + 1)
+ new_nodeset_count += 1
+ new_nodeset << XPathNode.new(node, position: new_nodeset_count)
  end
  end
  end

test/xpath/test_base.rb

@@ -451,6 +451,46 @@ def test_following
  # puts results
  #end
 
+ def test_nested_predicates
+ doc = Document.new <<-EOF
+ <div>
+ <div>
+ <test>ab</test>
+ <test>cd</test>
+ </div>
+ <div>
+ <test>ef</test>
+ <test>gh</test>
+ </div>
+ <div>
+ <test>hi</test>
+ </div>
+ </div>
+ EOF
+
+ matches = XPath.match(doc, '(/div/div/test[0])').map(&:text)
+ assert_equal [], matches
+ matches = XPath.match(doc, '(/div/div/test[1])').map(&:text)
+ assert_equal ["ab", "ef", "hi"], matches
+ matches = XPath.match(doc, '(/div/div/test[2])').map(&:text)
+ assert_equal ["cd", "gh"], matches
+ matches = XPath.match(doc, '(/div/div/test[3])').map(&:text)
+ assert_equal [], matches
+
+ matches = XPath.match(doc, '(/div/div/test[1])[1]').map(&:text)
+ assert_equal ["ab"], matches
+ matches = XPath.match(doc, '(/div/div/test[1])[2]').map(&:text)
+ assert_equal ["ef"], matches
+ matches = XPath.match(doc, '(/div/div/test[1])[3]').map(&:text)
+ assert_equal ["hi"], matches
+ matches = XPath.match(doc, '(/div/div/test[2])[1]').map(&:text)
+ assert_equal ["cd"], matches
+ matches = XPath.match(doc, '(/div/div/test[2])[2]').map(&:text)
+ assert_equal ["gh"], matches
+ matches = XPath.match(doc, '(/div/div/test[2])[3]').map(&:text)
+ assert_equal [], matches
+ end
+
  # Contributed by Mike Stok
  def test_starts_with
  source = <<-EOF