/// <summary>
/// Starts the generation of a <see cref="TagHelperChunk"/>.
/// </summary>
/// <param name="target">
/// The <see cref="Block"/> responsible for this <see cref="TagHelperCodeGenerator"/>.
/// </param>
/// <param name="context">A <see cref="CodeGeneratorContext"/> instance that contains information about
/// the current code generation process.</param>
public override void GenerateStartBlockCode(Block target, CodeGeneratorContext context)
{
var tagHelperBlock = target as TagHelperBlock;
if (tagHelperBlock == null)
{
throw new ArgumentException(
RazorResources.TagHelpers_TagHelperCodeGeneartorMustBeAssociatedWithATagHelperBlock);
}
var attributes = new List<KeyValuePair<string, Chunk>>();
// We need to create a code generator to create chunks for each of the attributes.
var codeGenerator = context.Host.CreateCodeGenerator(
context.ClassName,
context.RootNamespace,
context.SourceFile);
foreach (var attribute in tagHelperBlock.Attributes)
{
ChunkBlock attributeChunkValue = null;
if (attribute.Value != null)
{
// Populates the code tree with chunks associated with attributes
attribute.Value.Accept(codeGenerator);
var chunks = codeGenerator.Context.CodeTreeBuilder.CodeTree.Chunks;
var first = chunks.FirstOrDefault();
attributeChunkValue = new ChunkBlock
{
Association = first?.Association,
Children = chunks,
Start = first == null ? SourceLocation.Zero : first.Start
};
}
attributes.Add(new KeyValuePair<string, Chunk>(attribute.Key, attributeChunkValue));
// Reset the code tree builder so we can build a new one for the next attribute
codeGenerator.Context.CodeTreeBuilder = new CodeTreeBuilder();
}
var unprefixedTagName = tagHelperBlock.TagName.Substring(_tagHelperDescriptors.First().Prefix.Length);
context.CodeTreeBuilder.StartChunkBlock(
new TagHelperChunk(
unprefixedTagName,
tagHelperBlock.SelfClosing,
attributes,
_tagHelperDescriptors),
target,
topLevel: false);
}
protected abstract void Visit(ChunkBlock chunk);
