/*
 * Copyright (c) 2001, DecisionSoft Limited All rights reserved.
 * Please see LICENSE.TXT for more information.
 */

#ifndef _AGGREGATEFUNCTION_HPP
#define _AGGREGATEFUNCTION_HPP

#include <pathan/functionAPI/ConstantFoldingFunction.hpp>

/** Virtual interface class for functions */
class PATHAN_EXPORT AggregateFunction : public ConstantFoldingFunction
{
public:

  /// constructor, checks for the correct number of arguments.
  AggregateFunction(const XMLCh* name,unsigned int argsFrom, unsigned int argsTo, const char* paramDecl, const VectorOfDataItems &args, XPath2MemoryManager* memMgr);

protected:
  /* 
   * returns a sequence with untypedAtomic values casted to the type of the other values in the sequence
   * or if all values are untypedAtomic they are cast to the convertType. 
   * If the items aren't all the same type (or untypedAtomic) an exception is thrown.   
   */
  virtual Sequence validateSequence(Sequence sequence, DynamicContext* context) const;

  // is the type specified by the given URI/Name pair a numeric one?
  bool isNumericType(const XMLCh* typeURI, const XMLCh* typeName, const DynamicContext* context) const;  

  // is the item a NaN?
  bool isNumericNaN(const Item* item) const;

};
#endif // _AGGREGATEFUNCTION_HPP