#include "../config/pathan_config.h"
/*
 * Copyright (c) 2001, DecisionSoft Limited All rights reserved.
 * Please see LICENSE.TXT for more information.
 */

#include <pathan/functions/FunctionZeroOrOne.hpp>
#include <pathan/Sequence.hpp>
#include <pathan/DynamicContext.hpp>
#include <pathan/exceptions/FunctionException.hpp>

const XMLCh FunctionZeroOrOne::name[] = { XERCES_CPP_NAMESPACE_QUALIFIER chLatin_z, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_e, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_r, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_o, XERCES_CPP_NAMESPACE_QUALIFIER chDash, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_o, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_r, XERCES_CPP_NAMESPACE_QUALIFIER chDash, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_o, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_n, XERCES_CPP_NAMESPACE_QUALIFIER chLatin_e, XERCES_CPP_NAMESPACE_QUALIFIER chNull };

/*
 * fn:zero-or-one($arg as item()*) as item()?
 */

FunctionZeroOrOne::FunctionZeroOrOne(const VectorOfDataItems &args, XPath2MemoryManager* memMgr)
  : ConstantFoldingFunction(name,1, 1, "item()*", args, memMgr)
{
}

Sequence FunctionZeroOrOne::collapseTreeInternal(DynamicContext* context, int flags) const
{
  Sequence arg = getParamNumber(1,context,DataItem::RETURN_TWO);

	if (arg.getLength() == 0 || arg.getLength() == 1) {
    return arg;
  } else {
    DSLthrow(FunctionException, X("FunctionZeroOrOne::collapseTreeInternal"),X("fn:zero-or-one called with a sequence containing more than one item"));
  }
}