private LambdaExpression GetLambdaForSimpleProperty <T>(IncludePathMetadataFragment includePathMetadataFragment, LambdaExpression filterLambda)
{
var lambdaType = typeof(Func <,>).GetGenericTypeDefinition().MakeGenericType(includePathMetadataFragment.DeclaringType, includePathMetadataFragment.PropertyType);
var rootParameter = Expression.Parameter(includePathMetadataFragment.DeclaringType);
var propertyLambda = Expression.Lambda(lambdaType, includePathMetadataFragment.PropertyAccessExpression, rootParameter);
return(ParameterToMemberExpressionRebinder.CombineSinglePropertySelectorWithPredicate(propertyLambda, filterLambda));
}
/// <summary>
/// Modifies an expression, rebinding the usage of parameter x to the usage of a property on parameter x.
/// </summary>
/// <param name="propertySelector">The expression to replace the original parameter with.</param>
/// <param name="propertyPredicate">The predicate built on the original parameter.</param>
/// <returns>A predicate on the rebound root expression.</returns>
public static LambdaExpression CombineSinglePropertySelectorWithPredicate(
LambdaExpression propertySelector,
LambdaExpression propertyPredicate)
{
var memberExpression = propertySelector.Body as MemberExpression;
var containingType = memberExpression.Member.DeclaringType;
if (memberExpression == null)
{
throw new ArgumentException("propertySelector");
}
var rootPredicateType = typeof(Func <,>).GetGenericTypeDefinition().MakeGenericType(containingType, typeof(bool));
var expr = Expression.Lambda(rootPredicateType, propertyPredicate.Body, propertySelector.Parameters);
var rebinder = new ParameterToMemberExpressionRebinder(propertyPredicate.Parameters[0], memberExpression);
expr = (LambdaExpression)rebinder.Visit(expr);
return(expr);
}
