diff --git a/.bzrignore b/.bzrignore
index c72c1ba3..4be526c7 100644
--- a/.bzrignore
+++ b/.bzrignore
@@ -34,3 +34,4 @@ vs9/mangle.sln
 *.stackdump
 *.lnk
 spec
+gmon.out
diff --git a/include/XPath/impl/xpath_arithmetic.hpp b/include/XPath/impl/xpath_arithmetic.hpp
index d81614e3..a03e55b0 100644
--- a/include/XPath/impl/xpath_arithmetic.hpp
+++ b/include/XPath/impl/xpath_arithmetic.hpp
@@ -1,6 +1,7 @@
 #ifndef ARABICA_XPATHIC_XPATH_ARITHMETIC_HPP
 #define ARABICA_XPATHIC_XPATH_ARITHMETIC_HPP
 
+#include <functional>
 #include "xpath_value.hpp"
 
 namespace Arabica
@@ -10,12 +11,12 @@ namespace XPath
 namespace impl
 {
 
-template<class string_type, class string_adaptor>
-class PlusOperator : public BinaryExpression<string_type, string_adaptor>
+template<class string_type, class string_adaptor, class Op>
+class ArithmeticOperator : public BinaryExpression<string_type, string_adaptor>
 {
   typedef BinaryExpression<string_type, string_adaptor> baseT;
 public:
-  PlusOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, XPathExpression_impl<string_type, string_adaptor>* rhs) : 
+  ArithmeticOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, XPathExpression_impl<string_type, string_adaptor>* rhs) : 
       BinaryExpression<string_type, string_adaptor>(lhs, rhs) { }
 
   virtual ValueType type() const { return NUMBER; }
@@ -23,81 +24,67 @@ public:
   virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
                                               const ExecutionContext<string_type, string_adaptor>& executionContext) const 
   {
-    return NumericValue<string_type, string_adaptor>::createValue(baseT::lhs()->evaluateAsNumber(context, executionContext) + baseT::rhs()->evaluateAsNumber(context, executionContext));
+    return NumericValue<string_type, string_adaptor>::createValue(evaluateAsNumber(context, executionContext));
   } // evaluate
+
+  virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context, 
+                                  const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  {
+    return Op()(baseT::lhs()->evaluateAsNumber(context, executionContext),
+                baseT::rhs()->evaluateAsNumber(context, executionContext));
+  } // evaluateAsNumber
+}; // class ArithmeticOperator
+
+template<class string_type, class string_adaptor>
+class PlusOperator : public ArithmeticOperator<string_type, string_adaptor, std::plus<double> >
+{
+public:
+  PlusOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, XPathExpression_impl<string_type, string_adaptor>* rhs) : 
+      ArithmeticOperator<string_type, string_adaptor, std::plus<double> >(lhs, rhs) { }
 }; // class PlusOperator
 
 template<class string_type, class string_adaptor>
-class MinusOperator : public BinaryExpression<string_type, string_adaptor>
+class MinusOperator : public ArithmeticOperator<string_type, string_adaptor, std::minus<double> >
 {
-  typedef BinaryExpression<string_type, string_adaptor> baseT;
 public:
   MinusOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, XPathExpression_impl<string_type, string_adaptor>* rhs) : 
-      BinaryExpression<string_type, string_adaptor>(lhs, rhs) { }
-
-  virtual ValueType type() const { return NUMBER; }
-
-  virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
-                                              const ExecutionContext<string_type, string_adaptor>& executionContext) const
-  {
-    return NumericValue<string_type, string_adaptor>::createValue(baseT::lhs()->evaluateAsNumber(context, executionContext) - baseT::rhs()->evaluateAsNumber(context, executionContext));
-  } // evaluate
+      ArithmeticOperator<string_type, string_adaptor, std::minus<double> >(lhs, rhs) { }
 }; // class MinusOperator
 
 template<class string_type, class string_adaptor>
-class MultiplyOperator : public BinaryExpression<string_type, string_adaptor>
+class MultiplyOperator : public ArithmeticOperator<string_type, string_adaptor, std::multiplies<double> >
 {
-  typedef BinaryExpression<string_type, string_adaptor> baseT;
 public:
   MultiplyOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, XPathExpression_impl<string_type, string_adaptor>* rhs) :
-      BinaryExpression<string_type, string_adaptor>(lhs, rhs) { }
-
-  virtual ValueType type() const { return NUMBER; }
-
-  virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
-                                              const ExecutionContext<string_type, string_adaptor>& executionContext) const
-  {
-    return NumericValue<string_type, string_adaptor>::createValue(baseT::lhs()->evaluateAsNumber(context, executionContext) * baseT::rhs()->evaluateAsNumber(context, executionContext));
-  } // evaluate
+      ArithmeticOperator<string_type, string_adaptor, std::multiplies<double> >(lhs, rhs) { }
 }; // class MultiplyOperator
 
 template<class string_type, class string_adaptor>
-class DivideOperator : public BinaryExpression<string_type, string_adaptor>
+class DivideOperator : public ArithmeticOperator<string_type, string_adaptor, std::divides<double> >
 {
-  typedef BinaryExpression<string_type, string_adaptor> baseT;
 public:
   DivideOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, XPathExpression_impl<string_type, string_adaptor>* rhs) :
-      BinaryExpression<string_type, string_adaptor>(lhs, rhs) { }
-
-  virtual ValueType type() const { return NUMBER; }
-
-  virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
-                                              const ExecutionContext<string_type, string_adaptor>& executionContext) const
-  {
-    return NumericValue<string_type, string_adaptor>::createValue(baseT::lhs()->evaluateAsNumber(context, executionContext) / baseT::rhs()->evaluateAsNumber(context, executionContext));
-  } // evaluate
+      ArithmeticOperator<string_type, string_adaptor, std::divides<double> >(lhs, rhs) { }
 }; // class DivideOperator
 
+
+struct NaN_aware_modulus
+{	
+  double operator()(const double& lhs, const double& rhs) const
+	{	// apply operator% to operands 
+    if(isNaN(lhs) || isNaN(rhs)) 
+      return NaN; 
+    return (static_cast<long>(lhs) % static_cast<long>(rhs)); 
+	}
+}; // NaN_aware_modulus
+
 template<class string_type, class string_adaptor>
-class ModOperator : public BinaryExpression<string_type, string_adaptor>
+class ModOperator : public ArithmeticOperator<string_type, string_adaptor, NaN_aware_modulus>
 {
   typedef BinaryExpression<string_type, string_adaptor> baseT;
 public:
   ModOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, XPathExpression_impl<string_type, string_adaptor>* rhs) :
-      BinaryExpression<string_type, string_adaptor>(lhs, rhs) { }
-
-  virtual ValueType type() const { return NUMBER; }
-
-  virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
-                                              const ExecutionContext<string_type, string_adaptor>& executionContext) const
-  {
-    double l = baseT::lhs()->evaluateAsNumber(context, executionContext);
-    double r = baseT::rhs()->evaluateAsNumber(context, executionContext);
-
-    if(isNaN(l) || isNaN(r))
-      return NumericValue<string_type, string_adaptor>::createValue(NaN);
-    return NumericValue<string_type, string_adaptor>::createValue(static_cast<long>(l) % static_cast<long>(r));
-  } // evaluate
+      ArithmeticOperator<string_type, string_adaptor, NaN_aware_modulus>(lhs, rhs) { }
 }; // class ModOperator
 
 template<class string_type, class string_adaptor>
@@ -113,8 +100,13 @@ public:
   virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
                                               const ExecutionContext<string_type, string_adaptor>& executionContext) const
   {
-    return NumericValue<string_type, string_adaptor>::createValue(-baseT::expr()->evaluate(context, executionContext).asNumber());
+    return NumericValue<string_type, string_adaptor>::createValue(evaluateAsNumber(context, executionContext));
   } // evaluate
+  virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context, 
+                                  const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  {
+    return -baseT::expr()->evaluateAsNumber(context, executionContext);
+  } // evaluateAsNumber
 }; // class UnaryNegative
 
 } // namespace impl
diff --git a/include/XPath/impl/xpath_expression.hpp b/include/XPath/impl/xpath_expression.hpp
index 897dfe9c..389ed03f 100644
--- a/include/XPath/impl/xpath_expression.hpp
+++ b/include/XPath/impl/xpath_expression.hpp
@@ -48,30 +48,58 @@ public:
 
   XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context) const
   {
-    ExecutionContext<string_type, string_adaptor> executionContext;
-    return evaluate(context, executionContext);
+    return evaluate(context, StaticExecutionContext());
   } // evaluate
+  virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context) const 
+  { 
+    return evaluateAsBool(context, StaticExecutionContext()); 
+  }
+  virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context) const 
+  { 
+    return evaluateAsNumber(context, StaticExecutionContext()); 
+  }
+  virtual string_type evaluateAsString(const DOM::Node<string_type, string_adaptor>& context) const 
+  { 
+    return evaluateAsString(context, StaticExecutionContext()); 
+  }
+  virtual NodeSet<string_type, string_adaptor> evaluateAsNodeSet(const DOM::Node<string_type, string_adaptor>& context) const 
+  { 
+    return evaluateAsNodeSet(context, StaticExecutionContext()); 
+  }
 
-  virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context) const { return evaluate(context).asBool(); }
-  virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context) const { return evaluate(context).asNumber(); }
-  virtual string_type evaluateAsString(const DOM::Node<string_type, string_adaptor>& context) const { return evaluate(context).asString(); }
-  virtual NodeSet<string_type, string_adaptor> evaluateAsNodeSet(const DOM::Node<string_type, string_adaptor>& context) const { return evaluate(context).asNodeSet(); }
-
-  virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
+   virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
                                               const ExecutionContext<string_type, string_adaptor>& executionContext) const = 0;
 
   virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context, 
-															const ExecutionContext<string_type, string_adaptor>& executionContext) const { return evaluate(context, executionContext).asBool(); }
+															const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  { 
+    return evaluate(context, executionContext).asBool(); 
+  }
   virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context, 
-                                  const ExecutionContext<string_type, string_adaptor>& executionContext) const { return evaluate(context, executionContext).asNumber(); }
+                                  const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  { 
+    return evaluate(context, executionContext).asNumber(); 
+  }
   virtual string_type evaluateAsString(const DOM::Node<string_type, string_adaptor>& context, 
-                                       const ExecutionContext<string_type, string_adaptor>& executionContext) const { return evaluate(context, executionContext).asString(); }
+                                       const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  { 
+    return evaluate(context, executionContext).asString(); 
+  }
   virtual NodeSet<string_type, string_adaptor> evaluateAsNodeSet(const DOM::Node<string_type, string_adaptor>& context, 
-                                                 const ExecutionContext<string_type, string_adaptor>& executionContext) const { return evaluate(context, executionContext).asNodeSet(); }
+                                                 const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  {
+    return evaluate(context, executionContext).asNodeSet(); 
+  }
 
   virtual void scan(impl::Expression_scanner<string_type, string_adaptor>& scanner) const { scanner.scan(this); }
 
 private:
+  static const ExecutionContext<string_type, string_adaptor>& StaticExecutionContext() 
+  {
+    static ExecutionContext<string_type, string_adaptor> executionContext;
+    return executionContext;
+  } // StaticExecutionContext
+
   XPathExpression_impl(const XPathExpression_impl&);
   bool operator==(const XPathExpression_impl&);
   XPathExpression_impl& operator=(const XPathExpression_impl&);
diff --git a/include/XPath/impl/xpath_logical.hpp b/include/XPath/impl/xpath_logical.hpp
index aa14d481..773d4212 100644
--- a/include/XPath/impl/xpath_logical.hpp
+++ b/include/XPath/impl/xpath_logical.hpp
@@ -1,66 +1,81 @@
-#ifndef ARABICA_XPATHIC_XPATH_LOGICAL_HPP
-#define ARABICA_XPATHIC_XPATH_LOGICAL_HPP
-
-#include "xpath_value.hpp"
-
-namespace Arabica
-{
-namespace XPath
-{
-namespace impl
-{
-
-template<class string_type, class string_adaptor>
-class OrOperator : public BinaryExpression<string_type, string_adaptor>
-{
-  typedef BinaryExpression<string_type, string_adaptor> baseT;
-public:
-  OrOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, 
-             XPathExpression_impl<string_type, string_adaptor>* rhs) :
-       BinaryExpression<string_type, string_adaptor>(lhs, rhs) { }
-
-  virtual ValueType type() const { return BOOL; }
-
-  virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
-                                              const ExecutionContext<string_type, string_adaptor>& executionContext) const
-  {
-    // From XPath 1.0 Rec, section 3.4
-    // An or expression is evaluated by evaluating each operand and converting its value 
-    // to a boolean as if by a call to the boolean function. The result is true if either 
-    // value is true and false otherwise. The right operand is not evaluated if the 
-    // left operand evaluates to true.
-    if(baseT::lhs()->evaluate(context, executionContext).asBool())
-      return BoolValue<string_type, string_adaptor>::createValue(true);
-    return BoolValue<string_type, string_adaptor>::createValue(baseT::rhs()->evaluate(context, executionContext).asBool());
-  } // evaluate
-}; // class OrOperator
-
-template<class string_type, class string_adaptor>
-class AndOperator : public BinaryExpression<string_type, string_adaptor>
-{
-  typedef BinaryExpression<string_type, string_adaptor> baseT;
-public:
-  AndOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, 
-              XPathExpression_impl<string_type, string_adaptor>* rhs) :
-       BinaryExpression<string_type, string_adaptor>(lhs, rhs) { }
-
-  virtual ValueType type() const { return BOOL; }
-
-  virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
-                                              const ExecutionContext<string_type, string_adaptor>& executionContext) const
-  {
-    // From XPath 1.0 Rec, section 3.4
-    // An and expression is evaluated by evaluating each operand and converting its value 
-    // to a boolean as if by a call to the boolean function. The result is true if both 
-    // values are true and false otherwise. The right operand is not evaluated if the left 
-    // operand evaluates to false.
-    if(!baseT::lhs()->evaluate(context, executionContext).asBool())
-      return BoolValue<string_type, string_adaptor>::createValue(false);
-    return BoolValue<string_type, string_adaptor>::createValue(baseT::rhs()->evaluate(context, executionContext).asBool());
-  } // evaluate
-}; // class AndOperator
-
-} // namespace impl
-} // namespace XPath
-} // namespace Arabica
-#endif 
+#ifndef ARABICA_XPATHIC_XPATH_LOGICAL_HPP
+#define ARABICA_XPATHIC_XPATH_LOGICAL_HPP
+
+#include "xpath_value.hpp"
+
+namespace Arabica
+{
+namespace XPath
+{
+namespace impl
+{
+
+
+template<class string_type, class string_adaptor>
+class LogicalOperator : public BinaryExpression<string_type, string_adaptor>
+{
+public:
+  LogicalOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, XPathExpression_impl<string_type, string_adaptor>* rhs) : 
+      BinaryExpression<string_type, string_adaptor>(lhs, rhs) { }
+
+  virtual ValueType type() const { return BOOL; }
+
+  virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context, 
+                                                           const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  {
+    return BoolValue<string_type, string_adaptor>::createValue(evaluateAsBool(context, executionContext));
+  } // evaluate
+}; // class LogicalOperator
+
+template<class string_type, class string_adaptor>
+class OrOperator : public LogicalOperator<string_type, string_adaptor>
+{
+  typedef LogicalOperator<string_type, string_adaptor> LogicalOperatorT;
+  using LogicalOperatorT::lhs;
+  using LogicalOperatorT::rhs;
+public:
+  OrOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, 
+             XPathExpression_impl<string_type, string_adaptor>* rhs) :
+       LogicalOperator<string_type, string_adaptor>(lhs, rhs) { }
+
+  virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context, 
+                              const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  {
+    // From XPath 1.0 Rec, section 3.4
+    // An or expression is evaluated by evaluating each operand and converting its value 
+    // to a boolean as if by a call to the boolean function. The result is true if either 
+    // value is true and false otherwise. The right operand is not evaluated if the 
+    // left operand evaluates to true.
+    return lhs()->evaluate(context, executionContext).asBool() || 
+           rhs()->evaluate(context, executionContext).asBool();
+  } // evaluateAsBool
+}; // class OrOperator
+
+template<class string_type, class string_adaptor>
+class AndOperator : public LogicalOperator<string_type, string_adaptor>
+{
+  typedef LogicalOperator<string_type, string_adaptor> LogicalOperatorT;
+  using LogicalOperatorT::lhs;
+  using LogicalOperatorT::rhs;
+public:
+  AndOperator(XPathExpression_impl<string_type, string_adaptor>* lhs, 
+              XPathExpression_impl<string_type, string_adaptor>* rhs) :
+       LogicalOperator<string_type, string_adaptor>(lhs, rhs) { }
+
+  virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context, 
+                              const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  {
+    // From XPath 1.0 Rec, section 3.4
+    // An and expression is evaluated by evaluating each operand and converting its value 
+    // to a boolean as if by a call to the boolean function. The result is true if both 
+    // values are true and false otherwise. The right operand is not evaluated if the left 
+    // operand evaluates to false.
+    return lhs()->evaluate(context, executionContext).asBool() &&
+           rhs()->evaluate(context, executionContext).asBool();
+  } // evaluateAsBool
+}; // class AndOperator
+
+} // namespace impl
+} // namespace XPath
+} // namespace Arabica
+#endif 
diff --git a/include/XPath/impl/xpath_value.hpp b/include/XPath/impl/xpath_value.hpp
index a2101314..63eac5d2 100644
--- a/include/XPath/impl/xpath_value.hpp
+++ b/include/XPath/impl/xpath_value.hpp
@@ -14,8 +14,49 @@ namespace Arabica
 namespace XPath
 {
 
+template<class string_type, class string_adaptor>
+class Value_base : public XPathValue_impl<string_type, string_adaptor>, public XPathExpression_impl<string_type, string_adaptor>
+{
+  typedef XPathValue_impl<string_type, string_adaptor> XPathValue_implT;
+  using XPathValue_implT::asBool;
+  using XPathValue_implT::asNumber;
+  using XPathValue_implT::asString;
+  using XPathValue_implT::asNodeSet;
+
+protected:
+  Value_base() { }
+  ~Value_base() { }
+
+public:
+  virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context) { return asBool(); }
+  virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context) { return asNumber(); }
+  virtual string_type evaluateAsString(const DOM::Node<string_type, string_adaptor>& context) { return asString(); }
+  virtual NodeSet<string_type, string_adaptor> evaluateAsNodeSet(const DOM::Node<string_type, string_adaptor>& context) { return asNodeSet(); }
+
+  virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context, 
+															const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  { 
+    return asBool(); 
+  }
+  virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context, 
+                                  const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  { 
+    return asNumber(); 
+  }
+  virtual string_type evaluateAsString(const DOM::Node<string_type, string_adaptor>& context, 
+                                       const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  { 
+    return asString(); 
+  }
+  virtual NodeSet<string_type, string_adaptor> evaluateAsNodeSet(const DOM::Node<string_type, string_adaptor>& context, 
+                                                 const ExecutionContext<string_type, string_adaptor>& executionContext) const 
+  {
+    return asNodeSet(); 
+  }
+}; // class Value_base
+
 template<class string_type, class string_adaptor = Arabica::default_string_adaptor<string_type> >
-class BoolValue : public XPathValue_impl<string_type, string_adaptor>, public XPathExpression_impl<string_type, string_adaptor>
+class BoolValue : public Value_base<string_type, string_adaptor>
 {
 public:
   BoolValue(bool value) :
@@ -28,10 +69,6 @@ public:
   {
     return XPathValue<string_type, string_adaptor>(new BoolValue(value_));
   } // evaluate
-  virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context) { return asBool(); }
-  virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context) { return asNumber(); }
-  virtual string_type evaluateAsString(const DOM::Node<string_type, string_adaptor>& context) { return asString(); }
-  virtual NodeSet<string_type, string_adaptor> evaluateAsNodeSet(const DOM::Node<string_type, string_adaptor>& context) { return asNodeSet(); }
 
   virtual bool asBool() const { return value_; }
   virtual double asNumber() const { return value_ ? 1 : 0; }
@@ -45,7 +82,7 @@ private:
 }; // class BoolValue
 
 template<class string_type, class string_adaptor = Arabica::default_string_adaptor<string_type> >
-class NumericValue : public XPathValue_impl<string_type, string_adaptor>, public XPathExpression_impl<string_type, string_adaptor>
+class NumericValue : public Value_base<string_type, string_adaptor>
 {
 public:
   NumericValue(double value) :
@@ -58,10 +95,6 @@ public:
   {
     return createValue(value_);
   } // evaluate
-  virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context) { return asBool(); }
-  virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context) { return asNumber(); }
-  virtual string_type evaluateAsString(const DOM::Node<string_type, string_adaptor>& context) { return asString(); }
-  virtual NodeSet<string_type, string_adaptor> evaluateAsNodeSet(const DOM::Node<string_type, string_adaptor>& context) { return asNodeSet(); }
 
   virtual bool asBool() const 
   { 
@@ -89,7 +122,7 @@ private:
 }; // class NumberValue
 
 template<class string_type, class string_adaptor = Arabica::default_string_adaptor<string_type> >
-class StringValue : public XPathValue_impl<string_type, string_adaptor>, public XPathExpression_impl<string_type, string_adaptor>
+class StringValue : public Value_base<string_type, string_adaptor>
 {
 public:
   StringValue(const char* value) :
@@ -104,10 +137,6 @@ public:
   {
     return XPathValue<string_type, string_adaptor>(new StringValue(value_));
   } // evaluate
-  virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context) { return asBool(); }
-  virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context) { return asNumber(); }
-  virtual string_type evaluateAsString(const DOM::Node<string_type, string_adaptor>& context) { return asString(); }
-  virtual NodeSet<string_type, string_adaptor> evaluateAsNodeSet() const { return asNodeSet(); }
 
   virtual bool asBool() const { return !string_adaptor::empty(value_); }
   virtual double asNumber() const 
@@ -124,7 +153,7 @@ private:
 }; // class StringValue
 
 template<class string_type, class string_adaptor = Arabica::default_string_adaptor<string_type> >
-class NodeSetValue : public XPathValue_impl<string_type, string_adaptor>, public XPathExpression_impl<string_type, string_adaptor>
+class NodeSetValue : public Value_base<string_type, string_adaptor>
 {
 public:
   NodeSetValue(const NodeSet<string_type, string_adaptor>& set) : set_(set) { }
@@ -139,10 +168,6 @@ public:
   {
     return XPathValue<string_type, string_adaptor>(this);
   } // evaluate
-  virtual bool evaluateAsBool(const DOM::Node<string_type, string_adaptor>& context) const{ return asBool(); }
-  virtual double evaluateAsNumber(const DOM::Node<string_type, string_adaptor>& context) const { return asNumber(); }
-  virtual string_type evaluateAsString(const DOM::Node<string_type, string_adaptor>& context) const { return asString(); }
-  virtual const NodeSet<string_type, string_adaptor>& evaluateAsNodeSet() const { return asNodeSet(); }
 
   virtual bool asBool() const 
   { 
diff --git a/include/XSLT/impl/handler/xslt_inline_element_handler.hpp b/include/XSLT/impl/handler/xslt_inline_element_handler.hpp
old mode 100644
new mode 100755
diff --git a/tests/XSLT/TO-DO b/tests/XSLT/TO-DO
index b25ada98..2ff38a3a 100644
--- a/tests/XSLT/TO-DO
+++ b/tests/XSLT/TO-DO
@@ -19,3 +19,10 @@ output combining (partially done for cdata-section-elements)
 
 
 Performance
+  variable pool
+  string pool?
+  use underlying_impl in XPath axis walker
+  use underlying_impl in XPath functions
+  short circuit evaluation in functions
+  only convert to full NodeSet at boundary
+  use a proxy to return propagate values out of functions
\ No newline at end of file