/// <summary>
/// Find the first IQueryable expression.
/// </summary>
/// <param name="expression">The current expression</param>
/// <returns>The iqueryable expression.</returns>
public static Expression Find(Expression expression)
{
RootQueryableFinder finder = new RootQueryableFinder();
finder.Visit(expression);
return(finder.root);
}
/// <summary>
/// Compiles the expression through the delegate.
/// </summary>
/// <param name="args">The arguments for the method to execute.</param>
internal void Compile(params object[] args)
{
if (this.fnQuery == null)
{
// First identify the query provider being used
Expression body = this.query.Body;
ConstantExpression root = RootQueryableFinder.Find(body) as ConstantExpression;
if (root == null && args != null && args.Length > 0)
{
Expression replaced = ExpressionReplacer.ReplaceAll(
body,
this.query.Parameters.ToArray(),
args.Select((a, i) => Expression.Constant(a, this.query.Parameters[i].Type)).ToArray()
);
body = PartialEvaluator.Eval(replaced);
root = RootQueryableFinder.Find(body) as ConstantExpression;
}
if (root == null)
{
throw new InvalidOperationException("Could not find query provider");
}
// Ask the query provider to compile the query by 'executing' the lambda expression
IQueryProvider provider = ((IQueryable)root.Value).Provider;
Delegate result = (Delegate)provider.Execute(this.query);
System.Threading.Interlocked.CompareExchange(ref this.fnQuery, result, null);
}
}
