private void ProcessDuplicates(IntermediateNode node)
{
// Reverse order because we will remove nodes.
//
// Each 'property' node could be duplicated if there are multiple tag helpers that match that
// particular attribute. This is common in our approach, which relies on 'fallback' tag helpers
// that overlap with more specific ones.
for (var i = node.Children.Count - 1; i >= 0; i--)
{
// For each usage of the general 'fallback' bind tag helper, it could duplicate
// the usage of a more specific one. Look for duplicates and remove the fallback.
var attribute = node.Children[i] as TagHelperPropertyIntermediateNode;
if (attribute != null &&
attribute.TagHelper != null &&
attribute.TagHelper.IsFallbackBindTagHelper())
{
for (var j = 0; j < node.Children.Count; j++)
{
var duplicate = node.Children[j] as TagHelperPropertyIntermediateNode;
if (duplicate != null &&
duplicate.TagHelper != null &&
duplicate.TagHelper.IsBindTagHelper() &&
duplicate.AttributeName == attribute.AttributeName &&
!object.ReferenceEquals(attribute, duplicate))
{
// Found a duplicate - remove the 'fallback' in favor of the
// more specific tag helper.
node.Children.RemoveAt(i);
break;
}
}
}
// Also treat the general <input bind="..." /> as a 'fallback' for that case and remove it.
// This is a workaround for a limitation where you can't write a tag helper that binds only
// when a specific attribute is **not** present.
if (attribute != null &&
attribute.TagHelper != null &&
attribute.TagHelper.IsInputElementFallbackBindTagHelper())
{
for (var j = 0; j < node.Children.Count; j++)
{
var duplicate = node.Children[j] as TagHelperPropertyIntermediateNode;
if (duplicate != null &&
duplicate.TagHelper != null &&
duplicate.TagHelper.IsInputElementBindTagHelper() &&
duplicate.AttributeName == attribute.AttributeName &&
!object.ReferenceEquals(attribute, duplicate))
{
// Found a duplicate - remove the 'fallback' input tag helper in favor of the
// more specific tag helper.
node.Children.RemoveAt(i);
break;
}
}
}
}
// If we still have duplicates at this point then they are genuine conflicts.
var duplicates = node.Children
.OfType <TagHelperPropertyIntermediateNode>()
.GroupBy(p => p.AttributeName)
.Where(g => g.Count() > 1);
foreach (var duplicate in duplicates)
{
node.Diagnostics.Add(ComponentDiagnosticFactory.CreateBindAttribute_Duplicates(
node.Source,
duplicate.Key,
duplicate.ToArray()));
foreach (var property in duplicate)
{
node.Children.Remove(property);
}
}
}
