private static TryParseResult TryParseBlock(
string tagName,
Block block,
IEnumerable <TagHelperDescriptor> descriptors,
ErrorSink errorSink)
{
// TODO: Accept more than just spans: https://github.com/aspnet/Razor/issues/96.
// The first child will only ever NOT be a Span if a user is doing something like:
// <input @checked />
var childSpan = block.Children.First() as Span;
if (childSpan == null || childSpan.Kind != SpanKind.Markup)
{
errorSink.OnError(
block.Start,
RazorResources.FormatTagHelpers_CannotHaveCSharpInTagDeclaration(tagName),
block.Length);
return(null);
}
var builder = new BlockBuilder(block);
// If there's only 1 child it means that it's plain text inside of the attribute.
// i.e. <div class="plain text in attribute">
if (builder.Children.Count == 1)
{
return(TryParseSpan(childSpan, descriptors, errorSink));
}
var nameSymbols = childSpan
.Symbols
.OfType <HtmlSymbol>()
.SkipWhile(symbol => !HtmlMarkupParser.IsValidAttributeNameSymbol(symbol)) // Skip prefix
.TakeWhile(nameSymbol => HtmlMarkupParser.IsValidAttributeNameSymbol(nameSymbol))
.Select(nameSymbol => nameSymbol.Content);
var name = string.Concat(nameSymbols);
if (string.IsNullOrEmpty(name))
{
errorSink.OnError(
childSpan.Start,
RazorResources.FormatTagHelpers_AttributesMustHaveAName(tagName),
childSpan.Length);
return(null);
}
// Have a name now. Able to determine correct isBoundNonStringAttribute value.
var result = CreateTryParseResult(name, descriptors);
var firstChild = builder.Children[0] as Span;
if (firstChild != null && firstChild.Symbols[0] is HtmlSymbol)
{
var htmlSymbol = firstChild.Symbols[firstChild.Symbols.Count - 1] as HtmlSymbol;
switch (htmlSymbol.Type)
{
// Treat NoQuotes and DoubleQuotes equivalently. We purposefully do not persist NoQuotes
// ValueStyles at code generation time to protect users from rendering dynamic content with spaces
// that can break attributes.
// Ex: <tag my-attribute=@value /> where @value results in the test "hello world".
// This way, the above code would render <tag my-attribute="hello world" />.
case HtmlSymbolType.Equals:
case HtmlSymbolType.DoubleQuote:
result.AttributeValueStyle = HtmlAttributeValueStyle.DoubleQuotes;
break;
case HtmlSymbolType.SingleQuote:
result.AttributeValueStyle = HtmlAttributeValueStyle.SingleQuotes;
break;
default:
result.AttributeValueStyle = HtmlAttributeValueStyle.Minimized;
break;
}
}
// Remove first child i.e. foo="
builder.Children.RemoveAt(0);
// Grabbing last child to check if the attribute value is quoted.
var endNode = block.Children.Last();
if (!endNode.IsBlock)
{
var endSpan = (Span)endNode;
// In some malformed cases e.g. <p bar="false', the last Span (false' in the ex.) may contain more
// than a single HTML symbol. Do not ignore those other symbols.
var symbolCount = endSpan.Symbols.Count();
var endSymbol = symbolCount == 1 ? (HtmlSymbol)endSpan.Symbols.First() : null;
// Checking to see if it's a quoted attribute, if so we should remove end quote
if (endSymbol != null && IsQuote(endSymbol))
{
builder.Children.RemoveAt(builder.Children.Count - 1);
}
}
// We need to rebuild the chunk generators of the builder and its children (this is needed to
// ensure we don't do special attribute chunk generation since this is a tag helper).
block = RebuildChunkGenerators(builder.Build(), result.IsBoundAttribute);
// If there's only 1 child at this point its value could be a simple markup span (treated differently than
// block level elements for attributes).
if (block.Children.Count() == 1)
{
var child = block.Children.First() as Span;
if (child != null)
{
// After pulling apart the block we just have a value span.
var spanBuilder = new SpanBuilder(child);
result.AttributeValueNode =
CreateMarkupAttribute(spanBuilder, result.IsBoundNonStringAttribute);
return(result);
}
}
var isFirstSpan = true;
result.AttributeValueNode = ConvertToMarkupAttributeBlock(
block,
(parentBlock, span) =>
{
// If the attribute was requested by a tag helper but the corresponding property was not a
// string, then treat its value as code. A non-string value can be any C# value so we need
// to ensure the SyntaxTreeNode reflects that.
if (result.IsBoundNonStringAttribute)
{
// For bound non-string attributes, we'll only allow a transition span to appear at the very
// beginning of the attribute expression. All later transitions would appear as code so that
// they are part of the generated output. E.g.
// key="@value" -> MyTagHelper.key = value
// key=" @value" -> MyTagHelper.key = @value
// key="1 + @case" -> MyTagHelper.key = 1 + @case
// key="@int + @case" -> MyTagHelper.key = int + @case
// key="@(a + b) -> MyTagHelper.key = a + b
// key="4 + @(a + b)" -> MyTagHelper.key = 4 + @(a + b)
if (isFirstSpan && span.Kind == SpanKind.Transition)
{
// do nothing.
}
else
{
var spanBuilder = new SpanBuilder(span);
if (parentBlock.Type == BlockType.Expression &&
(spanBuilder.Kind == SpanKind.Transition ||
spanBuilder.Kind == SpanKind.MetaCode))
{
// Change to a MarkupChunkGenerator so that the '@' \ parenthesis is generated as part of the output.
spanBuilder.ChunkGenerator = new MarkupChunkGenerator();
}
spanBuilder.Kind = SpanKind.Code;
span = spanBuilder.Build();
}
}
isFirstSpan = false;
return(span);
});
return(result);
}
// This method handles cases when the attribute is a simple span attribute such as
// class="something moresomething". This does not handle complex attributes such as
// class="@myclass". Therefore the span.Content is equivalent to the entire attribute.
private static TryParseResult TryParseSpan(
Span span,
IEnumerable <TagHelperDescriptor> descriptors,
ErrorSink errorSink)
{
var afterEquals = false;
var builder = new SpanBuilder
{
ChunkGenerator = span.ChunkGenerator,
EditHandler = span.EditHandler,
Kind = span.Kind
};
// Will contain symbols that represent a single attribute value: <input| class="btn"| />
var htmlSymbols = span.Symbols.OfType <HtmlSymbol>().ToArray();
var capturedAttributeValueStart = false;
var attributeValueStartLocation = span.Start;
// Default to DoubleQuotes. We purposefully do not persist NoQuotes ValueStyle to stay consistent with the
// TryParseBlock() variation of attribute parsing.
var attributeValueStyle = HtmlAttributeValueStyle.DoubleQuotes;
// The symbolOffset is initialized to 0 to expect worst case: "class=". If a quote is found later on for
// the attribute value the symbolOffset is adjusted accordingly.
var symbolOffset = 0;
string name = null;
// Iterate down through the symbols to find the name and the start of the value.
// We subtract the symbolOffset so we don't accept an ending quote of a span.
for (var i = 0; i < htmlSymbols.Length - symbolOffset; i++)
{
var symbol = htmlSymbols[i];
if (afterEquals)
{
// We've captured all leading whitespace, the attribute name, and an equals with an optional
// quote/double quote. We're now at: " asp-for='|...'" or " asp-for=|..."
// The goal here is to capture all symbols until the end of the attribute. Note this will not
// consume an ending quote due to the symbolOffset.
// When symbols are accepted into SpanBuilders, their locations get altered to be offset by the
// parent which is why we need to mark our start location prior to adding the symbol.
// This is needed to know the location of the attribute value start within the document.
if (!capturedAttributeValueStart)
{
capturedAttributeValueStart = true;
attributeValueStartLocation = span.Start + symbol.Start;
}
builder.Accept(symbol);
}
else if (name == null && HtmlMarkupParser.IsValidAttributeNameSymbol(symbol))
{
// We've captured all leading whitespace prior to the attribute name.
// We're now at: " |asp-for='...'" or " |asp-for=..."
// The goal here is to capture the attribute name.
var symbolContents = htmlSymbols
.Skip(i) // Skip prefix
.TakeWhile(nameSymbol => HtmlMarkupParser.IsValidAttributeNameSymbol(nameSymbol))
.Select(nameSymbol => nameSymbol.Content);
// Move the indexer past the attribute name symbols.
i += symbolContents.Count() - 1;
name = string.Concat(symbolContents);
attributeValueStartLocation = SourceLocation.Advance(attributeValueStartLocation, name);
}
else if (symbol.Type == HtmlSymbolType.Equals)
{
// We've captured all leading whitespace and the attribute name.
// We're now at: " asp-for|='...'" or " asp-for|=..."
// The goal here is to consume the equal sign and the optional single/double-quote.
// The coming symbols will either be a quote or value (in the case that the value is unquoted).
SourceLocation symbolStartLocation;
// Skip the whitespace preceding the start of the attribute value.
do
{
i++; // Start from the symbol after '='.
} while (i < htmlSymbols.Length &&
(htmlSymbols[i].Type == HtmlSymbolType.WhiteSpace ||
htmlSymbols[i].Type == HtmlSymbolType.NewLine));
// Check for attribute start values, aka single or double quote
if (i < htmlSymbols.Length && IsQuote(htmlSymbols[i]))
{
if (htmlSymbols[i].Type == HtmlSymbolType.SingleQuote)
{
attributeValueStyle = HtmlAttributeValueStyle.SingleQuotes;
}
symbolStartLocation = htmlSymbols[i].Start;
// If there's a start quote then there must be an end quote to be valid, skip it.
symbolOffset = 1;
}
else
{
// We are at the symbol after equals. Go back to equals to ensure we don't skip past that symbol.
i--;
symbolStartLocation = symbol.Start;
}
attributeValueStartLocation =
span.Start +
symbolStartLocation +
new SourceLocation(absoluteIndex: 1, lineIndex: 0, characterIndex: 1);
afterEquals = true;
}
else if (symbol.Type == HtmlSymbolType.WhiteSpace)
{
// We're at the start of the attribute, this branch may be hit on the first iterations of
// the loop since the parser separates attributes with their spaces included as symbols.
// We're at: "| asp-for='...'" or "| asp-for=..."
// Note: This will not be hit even for situations like asp-for ="..." because the core Razor
// parser currently does not know how to handle attributes in that format. This will be addressed
// by https://github.com/aspnet/Razor/issues/123.
attributeValueStartLocation = SourceLocation.Advance(attributeValueStartLocation, symbol.Content);
}
}
// After all symbols have been added we need to set the builders start position so we do not indirectly
// modify each symbol's Start location.
builder.Start = attributeValueStartLocation;
if (name == null)
{
// We couldn't find a name, if the original span content was whitespace it ultimately means the tag
// that owns this "attribute" is malformed and is expecting a user to type a new attribute.
// ex: <myTH class="btn"| |
if (!string.IsNullOrWhiteSpace(span.Content))
{
errorSink.OnError(
span.Start,
RazorResources.TagHelperBlockRewriter_TagHelperAttributeListMustBeWellFormed,
span.Content.Length);
}
return(null);
}
var result = CreateTryParseResult(name, descriptors);
// If we're not after an equal then we should treat the value as if it were a minimized attribute.
Span attributeValue = null;
if (afterEquals)
{
attributeValue = CreateMarkupAttribute(builder, result.IsBoundNonStringAttribute);
}
else
{
attributeValueStyle = HtmlAttributeValueStyle.Minimized;
}
result.AttributeValueNode = attributeValue;
result.AttributeValueStyle = attributeValueStyle;
return(result);
}