/// <summary>
/// Visits a LinqDistinctExpression. This expression is not supported in Linq to Astoria.
/// </summary>
/// <param name="expression">The expression.</param>
/// <returns>The result of visiting this expression.</returns>
public override QueryValue Visit(LinqDistinctExpression expression)
{
var source = this.EvaluateCollection(expression.Source);
var sourceError = QueryError.GetErrorFromValues(source.Elements);
var error = QueryError.Combine(sourceError, new QueryError("This expression is not supported in Linq to Astoria."));
return(expression.Source.ExpressionType.CreateErrorValue(error));
}
/// <summary>
/// Replaces the given expression.
/// </summary>
/// <param name="expression">Expression to replace.</param>
/// <returns>Replaced expression.</returns>
public virtual QueryExpression Visit(LinqDistinctExpression expression)
{
QueryExpression source = this.ReplaceExpression(expression.Source);
if (this.HasChanged(expression.Source, source))
{
return(new LinqDistinctExpression(source, expression.ExpressionType));
}
return(expression);
}
/// <summary>
/// Visits a QueryExpression tree whose root node is the LinqDistinctExpression.
/// </summary>
/// <param name="expression">The root node of the expression tree being visited.</param>
/// <returns>Uri query string representing the expression.</returns>
public virtual string Visit(LinqDistinctExpression expression)
{
throw new TaupoNotSupportedException("Not supported");
}
/// <summary>
/// Generates System.CodeDom.CodeExpression from the given expression.
/// </summary>
/// <param name="expression">Expression from which System.CodeDom.CodeExpression is generated.</param>
/// <returns>Generated System.CodeDom.CodeExpression.</returns>
public virtual CodeExpression Visit(LinqDistinctExpression expression)
{
CodeExpression source = this.GenerateCode(expression.Source);
return(source.Call("Distinct"));
}
/// <summary>
/// Evaluates the specified expression.
/// </summary>
/// <param name="expression">The expression to evaluate.</param>
/// <returns>Value of the expression.</returns>
public virtual QueryValue Visit(LinqDistinctExpression expression)
{
var source = this.EvaluateCollection(expression.Source);
return(source.Distinct());
}
/// <summary>
/// Resolves types for the specified expression.
/// </summary>
/// <param name="expression">The expression to resolve types for.</param>
/// <returns>Expression with resolved types.</returns>
public QueryExpression Visit(LinqDistinctExpression expression)
{
var source = this.ResolveTypes(expression.Source);
return(new LinqDistinctExpression(source, source.ExpressionType));
}
