Support for lexing empty XPath strings.

lib/oga/xpath/lexer.rl

@@ -201,8 +201,8 @@ module Oga
         dquote = '"';
         squote = "'";
 
-        string_dquote = (dquote ^dquote+ dquote);
-        string_squote = (squote ^squote+ squote);
+        string_dquote = (dquote ^dquote* dquote);
+        string_squote = (squote ^squote* squote);
 
         string = string_dquote | string_squote;
 

spec/oga/xpath/lexer/strings_spec.rb

@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+describe Oga::XPath::Lexer do
+  context 'strings' do
+    example 'lex a double quoted string' do
+      lex_xpath('"foo"').should == [[:T_STRING, 'foo']]
+    end
+
+    example 'lex a single quoted string' do
+      lex_xpath("'foo'").should == [[:T_STRING, 'foo']]
+    end
+
+    example 'lex an empty double quoted string' do
+      lex_xpath('""').should == [[:T_STRING, '']]
+    end
+
+    example 'lex an empty single quoted string' do
+      lex_xpath("''").should == [[:T_STRING, '']]
+    end
+  end
+end