private IQueryProvider FindProvider(Expression expression, object[] args)
{
ConstantExpression root = TypedSubtreeFinder.Find(expression,
typeof(IQueryProvider)) as ConstantExpression;
if (root == null)
{
root = TypedSubtreeFinder.Find(expression, typeof(IQueryable)) as ConstantExpression;
}
if (root == null && args != null && args.Length > 0)
{
Expression replaced = ExpressionReplacer.ReplaceAll(
expression, _expression.Parameters.ToArray(),
args.Select((a, i) => Expression.Constant(a, _expression.Parameters[i].Type)).ToArray()
);
Expression partial = PartialEvaluator.Eval(replaced);
return(FindProvider(partial, null));
}
if (root != null)
{
IQueryProvider provider = (root.Value as IQueryProvider);
if (provider == null)
{
IQueryable query = (root.Value as IQueryable);
if (query != null)
{
provider = query.Provider;
}
}
return(provider);
}
return(null);
}
/// <summary>
/// Convert the query expression into an execution plan
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
protected virtual Expression GetExecutionPlan(Expression expression)
{
// strip off lambda for now
LambdaExpression lambda = expression as LambdaExpression;
if (lambda != null)
{
expression = lambda.Body;
}
// translate query into client & server parts
Expression translation = this.Translate(expression);
Expression provider = TypedSubtreeFinder.Find(expression, typeof(DbQueryProvider));
if (provider == null)
{
Expression rootQueryable = TypedSubtreeFinder.Find(expression, typeof(IQueryable));
provider = Expression.Convert(
Expression.Property(rootQueryable, typeof(IQueryable).GetProperty("Provider")),
typeof(DbQueryProvider)
);
}
return(this.policy.BuildExecutionPlan(this.Mapping, translation, provider));
}
public static Expression Find(Expression expression, Type type)
{
TypedSubtreeFinder finder = new TypedSubtreeFinder(type);
finder.Visit(expression);
return finder._root;
}
public static Expression Find(Expression expression, Type type)
{
TypedSubtreeFinder finder = new TypedSubtreeFinder(type);
finder.Visit(expression);
return(finder._root);
}