private static AttributeCompletionContext BuildAttributeCompletionContext(
IEnumerable <TagHelperDescriptor> descriptors,
IEnumerable <string> existingCompletions,
string currentTagName,
string currentAttributeName = null,
IEnumerable <KeyValuePair <string, string> > attributes = null,
string tagHelperPrefix = "")
{
attributes = attributes ?? Enumerable.Empty <KeyValuePair <string, string> >();
var documentContext = TagHelperDocumentContext.Create(tagHelperPrefix, descriptors);
var completionContext = new AttributeCompletionContext(
documentContext,
existingCompletions,
currentTagName,
currentAttributeName,
attributes,
currentParentTagName: "body",
currentParentIsTagHelper: false,
inHTMLSchema: (tag) => tag == "strong" || tag == "b" || tag == "bold" || tag == "li" || tag == "div");
return(completionContext);
}
/*
* This API attempts to understand a users context as they're typing in a Razor file to provide TagHelper based attribute IntelliSense.
*
* Scenarios for TagHelper attribute IntelliSense follows:
* 1. TagHelperDescriptor's have matching required attribute names
* -> Provide IntelliSense for the required attributes of those descriptors to lead users towards a TagHelperified element.
* 2. TagHelperDescriptor entirely applies to current element. Tag name, attributes, everything is fulfilled.
* -> Provide IntelliSense for the bound attributes for the applied descriptors.
*
* Within each of the above scenarios if an attribute completion has a corresponding bound attribute we associate it with the corresponding
* BoundAttributeDescriptor. By doing this a user can see what C# type a TagHelper expects for the attribute.
*/
public override AttributeCompletionResult GetAttributeCompletions(AttributeCompletionContext completionContext)
{
if (completionContext == null)
{
throw new ArgumentNullException(nameof(completionContext));
}
var attributeCompletions = completionContext.ExistingCompletions.ToDictionary(
completion => completion,
_ => new HashSet <BoundAttributeDescriptor>(),
StringComparer.OrdinalIgnoreCase);
var documentContext = completionContext.DocumentContext;
var descriptorsForTag = _tagHelperFactsService.GetTagHelpersGivenTag(documentContext, completionContext.CurrentTagName, completionContext.CurrentParentTagName);
if (descriptorsForTag.Count == 0)
{
// If the current tag has no possible descriptors then we can't have any additional attributes.
var defaultResult = AttributeCompletionResult.Create(attributeCompletions);
return(defaultResult);
}
var prefix = documentContext.Prefix ?? string.Empty;
Debug.Assert(completionContext.CurrentTagName.StartsWith(prefix, StringComparison.OrdinalIgnoreCase));
var applicableTagHelperBinding = _tagHelperFactsService.GetTagHelperBinding(
documentContext,
completionContext.CurrentTagName,
completionContext.Attributes,
completionContext.CurrentParentTagName,
completionContext.CurrentParentIsTagHelper);
var applicableDescriptors = applicableTagHelperBinding?.Descriptors ?? Enumerable.Empty <TagHelperDescriptor>();
var unprefixedTagName = completionContext.CurrentTagName.Substring(prefix.Length);
if (!completionContext.InHTMLSchema(unprefixedTagName) &&
applicableDescriptors.All(descriptor => descriptor.TagOutputHint == null))
{
// This isn't a known HTML tag and no descriptor has an output element hint. Remove all previous completions.
attributeCompletions.Clear();
}
for (var i = 0; i < descriptorsForTag.Count; i++)
{
var descriptor = descriptorsForTag[i];
if (applicableDescriptors.Contains(descriptor))
{
foreach (var attributeDescriptor in descriptor.BoundAttributes)
{
UpdateCompletions(attributeDescriptor.Name, attributeDescriptor);
}
}
else
{
var htmlNameToBoundAttribute = descriptor.BoundAttributes.ToDictionary(attribute => attribute.Name, StringComparer.OrdinalIgnoreCase);
foreach (var rule in descriptor.TagMatchingRules)
{
foreach (var requiredAttribute in rule.Attributes)
{
if (htmlNameToBoundAttribute.TryGetValue(requiredAttribute.Name, out var attributeDescriptor))
{
UpdateCompletions(requiredAttribute.Name, attributeDescriptor);
}
else
{
UpdateCompletions(requiredAttribute.Name, possibleDescriptor: null);
}
}
}
}
}
var completionResult = AttributeCompletionResult.Create(attributeCompletions);
return(completionResult);
void UpdateCompletions(string attributeName, BoundAttributeDescriptor possibleDescriptor)
{
if (completionContext.Attributes.Any(attribute => string.Equals(attribute.Key, attributeName, StringComparison.OrdinalIgnoreCase)) &&
(completionContext.CurrentAttributeName == null ||
!string.Equals(attributeName, completionContext.CurrentAttributeName, StringComparison.OrdinalIgnoreCase)))
{
// Attribute is already present on this element and it is not the attribute in focus.
// It shouldn't exist in the completion list.
return;
}
if (!attributeCompletions.TryGetValue(attributeName, out var rules))
{
rules = new HashSet <BoundAttributeDescriptor>();
attributeCompletions[attributeName] = rules;
}
if (possibleDescriptor != null)
{
rules.Add(possibleDescriptor);
}
}
}