Add SymbolVisitor<TArgument, TResult> #55183
Description
Background and Motivation
In order to avoid shared state and allowing parallel invocations of the same visitor, it would be nice to be able to use a SymbolVisitor<TArgument, TResult>. We already have a similar pattern with OperationVisitor.
Proposed API
namespace Microsoft.CodeAnalysis
{
+ public abstract class SymbolVisitor<TArgument, TResult>
+ {
+ public virtual TResult? Visit(ISymbol? symbol, TArgument argument)
+ {
+ if (symbol != null)
+ {
+ return symbol.Accept(this, argument);
+ }
+
+ return default(TResult);
+ }
+
+ public virtual TResult? DefaultVisit(ISymbol symbol, TArgument argument)
+ {
+ return default(TResult);
+ }
+
+ public virtual TResult? VisitAlias(IAliasSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitArrayType(IArrayTypeSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitAssembly(IAssemblySymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitDiscard(IDiscardSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitDynamicType(IDynamicTypeSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitEvent(IEventSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitField(IFieldSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitLabel(ILabelSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitLocal(ILocalSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitMethod(IMethodSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitModule(IModuleSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitNamedType(INamedTypeSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitNamespace(INamespaceSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitParameter(IParameterSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitPointerType(IPointerTypeSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitFunctionPointerType(IFunctionPointerTypeSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitProperty(IPropertySymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitRangeVariable(IRangeVariableSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+
+ public virtual TResult? VisitTypeParameter(ITypeParameterSymbol symbol, TArgument argument)
+ {
+ return DefaultVisit(symbol, argument);
+ }
+ }
public interface ISymbol : IEquatable<ISymbol?>
{
// ...
void Accept(SymbolVisitor visitor);
TResult? Accept<TResult>(SymbolVisitor<TResult> visitor);
+ TResult? Accept<TArgument, TResult>(SymbolVisitor<TArgument, TResult> visitor, TArgument argument);
// ...
}
}Usage Examples
var result = symbol.Accept(new GenerateIdVisitor(), new GeneratorContext());Alternative Designs
It would be possible to implement a visitor based on dynamic invocation, however, I think this is not the optimal solution.
Risks
none I can think of