private bool TryRewriteTagHelperStart(
MarkupStartTagSyntax startTag,
MarkupEndTagSyntax endTag,
out MarkupTagHelperStartTagSyntax rewritten,
out TagHelperInfo tagHelperInfo)
{
rewritten = null;
tagHelperInfo = null;
// Get tag name of the current block
var tagName = startTag.GetTagNameWithOptionalBang();
// Could not determine tag name, it can't be a TagHelper, continue on and track the element.
if (string.IsNullOrEmpty(tagName) || tagName.StartsWith("!", StringComparison.Ordinal))
{
return(false);
}
TagHelperBinding tagHelperBinding;
if (!IsPotentialTagHelperStart(tagName, startTag))
{
return(false);
}
var tracker = CurrentTagHelperTracker;
var tagNameScope = tracker?.TagName ?? string.Empty;
// We're now in a start tag block, we first need to see if the tag block is a tag helper.
var elementAttributes = GetAttributeNameValuePairs(startTag);
tagHelperBinding = _tagHelperBinder.GetBinding(
tagName,
elementAttributes,
CurrentParentTagName,
CurrentParentIsTagHelper);
// If there aren't any TagHelperDescriptors registered then we aren't a TagHelper
if (tagHelperBinding == null)
{
// If the current tag matches the current TagHelper scope it means the parent TagHelper matched
// all the required attributes but the current one did not; therefore, we need to increment the
// OpenMatchingTags counter for current the TagHelperBlock so we don't end it too early.
// ex: <myth req="..."><myth></myth></myth> We don't want the first myth to close on the inside
// tag.
if (string.Equals(tagNameScope, tagName, StringComparison.OrdinalIgnoreCase))
{
tracker.OpenMatchingTags++;
}
return(false);
}
ValidateParentAllowsTagHelper(tagName, startTag);
ValidateBinding(tagHelperBinding, tagName, startTag);
// We're in a start TagHelper block.
ValidateStartTagSyntax(tagName, startTag);
var rewrittenStartTag = TagHelperBlockRewriter.Rewrite(
tagName,
_featureFlags,
startTag,
tagHelperBinding,
_errorSink,
_source);
var tagMode = TagHelperBlockRewriter.GetTagMode(startTag, endTag, tagHelperBinding);
tagHelperInfo = new TagHelperInfo(tagName, tagMode, tagHelperBinding);
rewritten = rewrittenStartTag;
return(true);
}
private bool TryRewriteTagHelper(Block tagBlock, ErrorSink errorSink)
{
// Get tag name of the current block (doesn't matter if it's an end or start tag)
var tagName = GetTagName(tagBlock);
// Could not determine tag name, it can't be a TagHelper, continue on and track the element.
if (tagName == null)
{
return(false);
}
TagHelperBinding tagHelperBinding;
if (!IsPotentialTagHelper(tagName, tagBlock))
{
return(false);
}
var tracker = _currentTagHelperTracker;
var tagNameScope = tracker?.TagName ?? string.Empty;
if (!IsEndTag(tagBlock))
{
// We're now in a start tag block, we first need to see if the tag block is a tag helper.
var elementAttributes = GetAttributeNameValuePairs(tagBlock);
tagHelperBinding = _tagHelperBinder.GetBinding(
tagName,
elementAttributes,
CurrentParentTagName,
CurrentParentIsTagHelper);
// If there aren't any TagHelperDescriptors registered then we aren't a TagHelper
if (tagHelperBinding == null)
{
// If the current tag matches the current TagHelper scope it means the parent TagHelper matched
// all the required attributes but the current one did not; therefore, we need to increment the
// OpenMatchingTags counter for current the TagHelperBlock so we don't end it too early.
// ex: <myth req="..."><myth></myth></myth> We don't want the first myth to close on the inside
// tag.
if (string.Equals(tagNameScope, tagName, StringComparison.OrdinalIgnoreCase))
{
tracker.OpenMatchingTags++;
}
return(false);
}
ValidateParentAllowsTagHelper(tagName, tagBlock, errorSink);
ValidateBinding(tagHelperBinding, tagName, tagBlock, errorSink);
// We're in a start TagHelper block.
var validTagStructure = ValidateTagSyntax(tagName, tagBlock, errorSink);
var builder = TagHelperBlockRewriter.Rewrite(
tagName,
validTagStructure,
_featureFlags,
tagBlock,
tagHelperBinding,
errorSink);
// Track the original start tag so the editor knows where each piece of the TagHelperBlock lies
// for formatting.
builder.SourceStartTag = tagBlock;
// Found a new tag helper block
TrackTagHelperBlock(builder);
// If it's a non-content expecting block then we don't have to worry about nested children within the
// tag. Complete it.
if (builder.TagMode == TagMode.SelfClosing || builder.TagMode == TagMode.StartTagOnly)
{
BuildCurrentlyTrackedTagHelperBlock(endTag: null);
}
}
else
{
// Validate that our end tag matches the currently scoped tag, if not we may need to error.
if (tagNameScope.Equals(tagName, StringComparison.OrdinalIgnoreCase))
{
// If there are additional end tags required before we can build our block it means we're in a
// situation like this: <myth req="..."><myth></myth></myth> where we're at the inside </myth>.
if (tracker.OpenMatchingTags > 0)
{
tracker.OpenMatchingTags--;
return(false);
}
ValidateTagSyntax(tagName, tagBlock, errorSink);
BuildCurrentlyTrackedTagHelperBlock(tagBlock);
}
else
{
tagHelperBinding = _tagHelperBinder.GetBinding(
tagName,
attributes: Array.Empty <KeyValuePair <string, string> >(),
parentTagName: CurrentParentTagName,
parentIsTagHelper: CurrentParentIsTagHelper);
// If there are not TagHelperDescriptors associated with the end tag block that also have no
// required attributes then it means we can't be a TagHelper, bail out.
if (tagHelperBinding == null)
{
return(false);
}
foreach (var descriptor in tagHelperBinding.Descriptors)
{
var boundRules = tagHelperBinding.GetBoundRules(descriptor);
var invalidRule = boundRules.FirstOrDefault(rule => rule.TagStructure == TagStructure.WithoutEndTag);
if (invalidRule != null)
{
// End tag TagHelper that states it shouldn't have an end tag.
errorSink.OnError(
RazorDiagnosticFactory.CreateParsing_TagHelperMustNotHaveAnEndTag(
new SourceSpan(SourceLocationTracker.Advance(tagBlock.Start, "</"), tagName.Length),
tagName,
descriptor.DisplayName,
invalidRule.TagStructure));
return(false);
}
}
// Current tag helper scope does not match the end tag. Attempt to recover the tag
// helper by looking up the previous tag helper scopes for a matching tag. If we
// can't recover it means there was no corresponding tag helper start tag.
if (TryRecoverTagHelper(tagName, tagBlock, errorSink))
{
ValidateParentAllowsTagHelper(tagName, tagBlock, errorSink);
ValidateTagSyntax(tagName, tagBlock, errorSink);
// Successfully recovered, move onto the next element.
}
else
{
// Could not recover, the end tag helper has no corresponding start tag, create
// an error based on the current childBlock.
errorSink.OnError(
RazorDiagnosticFactory.CreateParsing_TagHelperFoundMalformedTagHelper(
new SourceSpan(SourceLocationTracker.Advance(tagBlock.Start, "</"), tagName.Length), tagName));
return(false);
}
}
}
return(true);
}
