meowlang/parser/DeclarationVisitorNya.cs

using Antlr4.Runtime.Tree;
using meowlang.parser.antlr;

namespace meowlang.parser;

public class DeclarationVisitorNya : MeowBaseVisitorNya<TopLevelConstructModel>
{
    public override TopLevelConstructModel VisitTopLevelStatement(MeowParser.TopLevelStatementContext context)
    {
        var statement = new StatementVisitorNya().Visit(context);
        return new TopLevelStatementModel(context.GetSpan(), statement);
    }

    public override TopLevelConstructModel VisitFunction(MeowParser.FunctionContext context)
    {
        var attributes = context.attribute().Select(x => new AttributeVisitorNya().Visit(x)).ToList();
        var pub = context.pub != null;
        var name = context.name.Text;

        var typeParameters =
            context.genericParameters()?._name.Select(x => new TypeParameterModel(x.GetSpan(), x.Text)).ToList() ??
            new List<TypeParameterModel>();
        var functionParameters = context.functionParameters().functionParameter()
            .Select(x => new FunctionParameterVisitorNya().Visit(x)).ToList();
        var functionReturns = context.functionReturn()?.typeReference().Select(x => new TypeReferenceVisitorNya().Visit(x))
            .ToList() ?? new List<TypeReferenceModel>();
        var constraints = context.constraint()?.Select(x => new FunctionConstraintVisitorNya().Visit(x)).ToList() ??
                          new List<ConstraintModel>();

        var body = new ExpressionVisitorNya().Visit(context.body);

        return new FunctionModel(context.GetSpan(), attributes, pub, name, typeParameters, functionParameters,
            functionReturns, constraints, body);
    }

    public override ConstraintTopLevelConstructModel VisitConstraintDeclaration(
        MeowParser.ConstraintDeclarationContext context)
    {
        var attributes = context.attribute().Select(x => new AttributeVisitorNya().Visit(x)).ToList();
        var pub = context.pub != null;
        var name = context.name.Text;
        var typeNames = context._types.Select(x => x.Text).ToList();
        var rules = context.constraintRule().Select(x => new ConstraintRuleVisitorNya().Visit(x)).ToList();
        return new ConstraintTopLevelConstructModel(context.GetSpan(), attributes, pub, name, typeNames, rules);
    }

    public override TopLevelConstructModel VisitStructDeclaration(MeowParser.StructDeclarationContext context)
    {
        var attributes = context.attribute().Select(x => new AttributeVisitorNya().Visit(x)).ToList();
        var pub = context.pub != null;
        var name = context.name.Text;
        var typeParameters = context.genericParameters()?._name.Select(x => x.Text).ToList() ?? new List<string>();
        var constraints = context.constraint()?.Select(x => new FunctionConstraintVisitorNya().Visit(x)).ToList() ??
                          new List<ConstraintModel>();
        var structModel = new TypeReferenceVisitorNya().Visit(context.structType()) as StructTypeModel;
        return new StructTopLevelConstructModel(context.GetSpan(), attributes, pub, name, typeParameters, constraints, structModel!);
    }

    public override TopLevelConstructModel VisitEnumDeclaration(MeowParser.EnumDeclarationContext context)
    {
        var attributes = context.attribute().Select(x => new AttributeVisitorNya().Visit(x)).ToList();
        var pub = context.pub != null;
        var name = context.name.Text;
        var typeParameters = context.genericParameters()?._name.Select(x => x.Text).ToList() ?? new List<string>();
        var constraints = context.constraint()?.Select(x => new FunctionConstraintVisitorNya().Visit(x)).ToList() ??
                          new List<ConstraintModel>();

        var enumModel = new TypeReferenceVisitorNya().Visit(context.enumType()) as EnumTypeModel;
        return new EnumTopLevelConstructModel(context.GetSpan(), attributes, pub, name, typeParameters, constraints, enumModel!);
    }

    public override TopLevelConstructModel VisitTupleDeclaration(MeowParser.TupleDeclarationContext context)
    {
        var attributes = context.attribute().Select(x => new AttributeVisitorNya().Visit(x)).ToList();
        var pub = context.pub != null;
        var name = context.name.Text;
        var typeParameters = context.genericParameters()?._name.Select(x => x.Text).ToList() ?? new List<string>();
        var constraints = context.constraint()?.Select(x => new FunctionConstraintVisitorNya().Visit(x)).ToList() ??
                          new List<ConstraintModel>();
        var tupleModel = new TypeReferenceVisitorNya().Visit(context.tupleType()) as TupleTypeModel;
        return new TupleTopLevelConstructModel(context.GetSpan(), attributes, pub, name, typeParameters, constraints, tupleModel!);
    }

    public override TopLevelConstructModel VisitTypeAlias(MeowParser.TypeAliasContext context)
    {
        var attributes = context.attribute().Select(x => new AttributeVisitorNya().Visit(x)).ToList();
        var pub = context.pub != null;
        var name = context.name.Text;
        var typeParameters = context.genericParameters()?._name.Select(x => x.Text).ToList() ?? new List<string>();
        var type = new TypeReferenceVisitorNya().Visit(context.typeReference());
        return new TypeAliasModel(context.GetSpan(), attributes, pub, name, typeParameters, type);
    }
}

public class MeowBaseVisitorNya<T> : MeowBaseVisitor<T>
{
    public T? TryVisit(IParseTree? tree)
    {
        return tree == null ? default : Visit(tree);
    }
}