/// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public override ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     if (this._arg != null)
     {
         return new NormalizeUnicodeFunction(transformer.Transform(this._expr), transformer.Transform(this._arg));
     }
     else
     {
         return new NormalizeUnicodeFunction(transformer.Transform(this._expr));
     }
 }

        private static Expression ApplyTransformations(Expression expression)
        {
            var chain = new IExpressionTransformer[]
            {
                new PartialEvaluationTransformer(),
                new VbStringCompareTransformer(),
                new VbConvertInvocationTransformer(),
            };

            Expression result = expression;
            foreach (var transformer in chain)
            {
                expression = transformer.Transform(expression);
            }

            return expression;
        }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public override ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new NotEqualsExpression(transformer.Transform(this._leftExpr), transformer.Transform(this._rightExpr));
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public override ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new MultiplicationExpression(transformer.Transform(this._leftExpr), transformer.Transform(this._rightExpr));
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     if (this._optionExpr != null)
     {
         return new RegexFunction(transformer.Transform(this._textExpr), transformer.Transform(this._patternExpr), transformer.Transform(this._optionExpr));
     }
     else
     {
         return new RegexFunction(transformer.Transform(this._textExpr), transformer.Transform(this._patternExpr));
     }
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public override ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new InFunction(transformer.Transform(this._expr), this._expressions.Select(e => transformer.Transform(e)));
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public override ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new StartsWithFunction(transformer.Transform(this._expr), transformer.Transform(this._arg));
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new ConcatFunction(this._exprs.Select(e => transformer.Transform(e)));
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public override ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new XPathStringCast(transformer.Transform(this._expr));
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new StringJoinFunction(transformer.Transform(this._sep), this._exprs.Select(e => transformer.Transform(e)));
 }

 public ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new UnknownFunction(this._funcUri, this._args.Select(e => transformer.Transform(e)));
 }

 public ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new IfElseFunction(transformer.Transform(_condition), transformer.Transform(_ifBranch),
                               transformer.Transform(_elseBranch));
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public override ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new LeviathanCosecantFunction(transformer.Transform(this._expr), this._inverse);
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     ISparqlExpression temp = transformer.Transform(new GraphPatternTerm(this._pattern));
     if (temp is GraphPatternTerm)
     {
         return new ExistsFunction(((GraphPatternTerm)temp).Pattern, this._mustExist);
     }
     else
     {
         throw new RdfQueryException("Unable to transform an EXISTS/NOT EXISTS function since the expression transformer in use failed to transform the inner Graph Pattern Expression to another Graph Pattern Expression");
     }
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     if (this._3d)
     {
         return new CartesianFunction(transformer.Transform(this._x1), transformer.Transform(this._y1), transformer.Transform(this._z1), transformer.Transform(this._x2), transformer.Transform(this._y2), transformer.Transform(this._z2));
     }
     else
     {
         return new CartesianFunction(transformer.Transform(this._x1), transformer.Transform(this._y1), transformer.Transform(this._x2), transformer.Transform(this._y2));
     }
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     if (this._length != null)
     {
         return new SubstringFunction(transformer.Transform(this._expr), transformer.Transform(this._start), transformer.Transform(this._length));
     }
     else
     {
         return new SubstringFunction(transformer.Transform(this._expr), transformer.Transform(this._start));
     }
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public override ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new RoundHalfToEvenFunction(transformer.Transform(this._expr));
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public override ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     if (this._log10)
     {
         return new LogFunction(transformer.Transform(this._leftExpr));
     }
     else
     {
         return new LogFunction(transformer.Transform(this._leftExpr), transformer.Transform(this._rightExpr));
     }
 }

 /// <summary>
 /// Transforms the Expression using the given Transformer
 /// </summary>
 /// <param name="transformer">Expression Transformer</param>
 /// <returns></returns>
 public override ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return new BooleanCast(transformer.Transform(this._expr));
 }

 public ISparqlExpression Transform(IExpressionTransformer transformer)
 {
     return _end != null
                ? new ArqSubstringFunction(transformer.Transform(_expr), transformer.Transform(_start),
                                           transformer.Transform(_end))
                : new ArqSubstringFunction(transformer.Transform(_end), transformer.Transform(_start));
 }