public override EntitySet Load(Evaluant.NLinq.NLinqQuery query, string[] attributes, string orderby, int first, int max)
{
if (first <= 0)
throw new ArgumentException("first must be greater than 0");
if (max < 0)
throw new ArgumentException("max must be none negative");
XPathTransformer transformer = new XPathTransformer(Factory.Model);
string xpath = transformer.ConvertToXPath(query);
EntitySet result = LoadWithXPath(xpath);
LoadAttribute(result, attributes);
// sort
if (orderby != null)
result.Sort(orderby.Split(','));
// page
EntitySet pageResult = new EntitySet();
Utils.TruncateList(result, pageResult, first, max);
return pageResult;
}
public override object LoadScalar(NLinqQuery query)
{
XPathTransformer transformer = new XPathTransformer(false, this.Model);
string xpath = transformer.Visit(query);
object result = null;
result = _Document.CreateNavigator().Evaluate(xpath);
// Ensure the result in an Int32 in cas of a count()
if (query.Expression.Operands[0] is OPath.Expressions.Function)
result = Convert.ToInt32(result);
return result;
}
public override void Visit(Call call)
{
_ExprLevel.Push((int)_ExprLevel.Peek());
if(call.Name == "id")
{
XPathTransformer transformer = new XPathTransformer(false, _Model, _ExprLevel);
call.Operands[0].Accept(transformer);
string strQuote = transformer.Result.IndexOf("'") > 0 ? "\"" : "'"; // if id contains ' limiter is " else '
_Result = String.Concat(" @Id = concat( @Type, ':', ", strQuote, transformer.Result, strQuote, ")");
for(int i=1; i<call.Operands.Count; i++)
{
call.Operands[i].Accept(transformer);
strQuote = transformer.Result.IndexOf("'") > 0 ? "\"" : "'"; // if id contains ' limiter is " else '
_Result += String.Concat(" or @Id = concat( @Type, ':', ", strQuote, transformer.Result, strQuote, ")");
}
}
_ExprLevel.Pop();
}
public override object LoadScalar(string opath)
{
XPathTransformer transformer = new XPathTransformer(false, this.Model);
string query = string.Format("eval({0})", opath);
string xpath = transformer.ConvertToScalarXPath(query);
object result = null;
result = _Document.CreateNavigator().Evaluate(xpath);
// Ensure the result in an Int32 in cas of a count()
if (opath.Trim().StartsWith("count"))
result = Convert.ToInt32(result);
return result;
}
public override void Visit(UnaryOperator unaryop)
{
_ExprLevel.Push((int)_ExprLevel.Peek());
XPathTransformer transformer = new XPathTransformer(true, _Model, _ExprLevel);
unaryop.Operand.Accept(transformer);
_Result = UnaryOperatorToString(unaryop.Type) + "(" + transformer.Result + " )";
_ExprLevel.Pop();
}
public override void Visit(BinaryOperator binaryop)
{
_ExprLevel.Push((int)_ExprLevel.Peek());
XPathTransformer transformer = new XPathTransformer(true, _Model, _ExprLevel);
binaryop.LeftOperand.Accept(transformer);
string leftValue = String.Empty, rightValue = String.Empty;
if(binaryop.LeftOperand is Value)
{
if(binaryop.RightOperand is Function)
leftValue = transformer.Result;
else
leftValue = FormatValue(transformer.Result);
}
else
leftValue = transformer.Result;
binaryop.RightOperand.Accept(transformer);
if(binaryop.RightOperand is Value)
{
if(binaryop.LeftOperand is Function)
rightValue = transformer.Result;
else
rightValue = FormatValue(transformer.Result);
}
else
rightValue = transformer.Result;
_Result = String.Format("({0})", BinaryOperatorToString(binaryop.Type, leftValue, rightValue));
_ExprLevel.Pop();
}
public override void Visit(Function function)
{
_ExprLevel.Push((int)_ExprLevel.Peek());
XPathTransformer transformer;
switch(function.Type)
{
case FunctionEnum.Average :
transformer = new XPathTransformer(true, _Model, _ExprLevel);
function.Path.Accept(transformer);
_Result = String.Concat(" sum( ", transformer.Result, " ) div count( ", transformer.Result ," )");
break;
case FunctionEnum.Count :
transformer = new XPathTransformer(false, _Model, _ExprLevel);
function.Path.Accept(transformer);
_Result = String.Concat(" count( ", transformer.Result, " )");
break;
case FunctionEnum.Exists :
transformer = new XPathTransformer(false, _Model, _ExprLevel);
function.Path.Accept(transformer);
_Result = String.Concat(" count( ", transformer.Result, " ) > 0");
break;
case FunctionEnum.IsNull :
transformer = new XPathTransformer(true, _Model, _ExprLevel);
function.Path.Accept(transformer);
_Result = String.Concat(" count( ", transformer.Result, " ) = 0");
break;
case FunctionEnum.Max :
/// TODO: Needs exslt extensions
throw new NotImplementedException("The max() function is not implemented for this engine");
case FunctionEnum.Min :
/// TODO: Needs exslt extensions
throw new NotImplementedException("The min() function is not implemented for this engine");
case FunctionEnum.Sum :
transformer = new XPathTransformer(true, _Model, _ExprLevel);
function.Path.Accept(transformer);
_Result = String.Concat(" sum( ", transformer.Result, " )");
break;
}
_ExprLevel.Pop();
}
/// <summary>
/// Converts the Expression to a xpath expression.
/// </summary>
/// <param name="path">Expression.</param>
/// <param name="firstIsType">True if the first identifer is a type.</param>
/// <param name="lastIsAttribute">True if the latest identifer is an attribute.</param>
/// <param name="isInConstraint"><see langword="true"/> if [is in constraint]; otherwise, <see langword="false"/>.</param>
/// <returns></returns>
private string ConvertToXPath(Call call, bool firstIsType, bool lastIsAttribute, bool isInConstraint)
{
// eval(count(...) + 3 + 2 * sum(...))
string xpath = String.Empty;
if (call.Name == "eval")
{
// evaluate a scalar expression
XPathTransformer transformer = new XPathTransformer(true, _Model, _ExprLevel);
call.Operands[0].Accept(transformer);
xpath = transformer.Result;
}
return xpath;
}
/// <summary>
/// Converts a Constraint to the corresponding xpath.
/// </summary>
/// <param name="constraint">Constraint.</param>
/// <param name="attributeAtEnd"></param>
/// <returns></returns>
private string ConvertToXPath(Constraint constraint, bool attributeAtEnd)
{
_ExprLevel.Push((int)_ExprLevel.Peek());
// We must do as if the first identifier is not a Type but a reference or attribute's name.
// The first case is taken into account by the same method's Query overload
XPathTransformer transformer = new XPathTransformer(attributeAtEnd, _Model, _ExprLevel);
constraint.Accept(transformer);
_ExprLevel.Pop();
return transformer.Result;
}
