//private static Type GetCodeGeneratorTypeForAttribute(this INamedTypeSymbol attributeType, AttributeAssemblyLoaderCallback loader)
private static Type GetCodeGeneratorTypeForAttribute <TSymbol>(this TSymbol attributeType, LoadAssemblyCallback loader)
where TSymbol : ISymbol
{
Requires.NotNull(loader, nameof(loader));
Type LoadGeneratorTypeFromAssembly(string fullTypeName, string assemblyName)
{
var generatorType = assemblyName != null
? loader(new AssemblyName(assemblyName))?.GetType(fullTypeName)
: null;
if (generatorType == null)
{
Verify.FailOperation($"Unable to find code generator `{fullTypeName}´ in `{assemblyName}´.");
}
return(generatorType);
}
// ReSharper disable once InvertIf
if (attributeType != null)
{
var codeGenerationAttributeType = typeof(CodeGenerationAttributeAttribute);
foreach (var generatorCandidateAttribute in attributeType.GetAttributes()
.Where(x => x.AttributeClass.Name == codeGenerationAttributeType.Name))
{
var firstArg = generatorCandidateAttribute.ConstructorArguments.Single();
switch (firstArg.Value)
{
case INamedTypeSymbol typeOfValue:
// This was a typeof(T) expression
return(LoadGeneratorTypeFromAssembly(
typeOfValue.GetFullTypeName()
, typeOfValue.ContainingAssembly.Name));
case string typeName:
// This string is the full name of the type, which MAY be assembly-qualified.
var commaIndex = typeName.IndexOf(Comma);
var isAssemblyQualified = commaIndex >= 0;
if (isAssemblyQualified)
{
return(LoadGeneratorTypeFromAssembly(
typeName.Substring(0, commaIndex)
, typeName.Substring(commaIndex + 1).Trim()));
}
else
{
return(LoadGeneratorTypeFromAssembly(
typeName
, generatorCandidateAttribute.AttributeClass.ContainingAssembly.Name));
}
}
}
}
// Nothing found, but should short-circuit, i.e. "fail", i.e. throw, before reaching this moment.
return(null);
}
public static IEnumerable <TGenerator> LoadCodeGenerators <TGenerator>(this ImmutableArray <AttributeData> attributeData, LoadAssemblyCallback loader)
where TGenerator : class, ICodeGenerator
{
Requires.NotNull(loader, nameof(loader));
TGenerator CreateCodeGenerator(GeneratorTuple tuple)
{
var(generatorType, datum) = tuple;
var generator = Activator.CreateInstance(generatorType, datum);
Requires.NotNull(generator, nameof(generator));
// TODO: TBD: might be better if .Is<T> actually returned T... i.e. could simple `return Assumes.Is<ICodeGenerator>(generator);´
Assumes.Is <TGenerator>(generator);
return((TGenerator)generator);
}
return(attributeData
.Select(x => GeneratorTuple.Create(x.AttributeClass.GetCodeGeneratorTypeForAttribute(loader), x))
.Where(tuple => tuple.GeneratorType != null).Select(CreateCodeGenerator));
}
