SyntaxHelper.cs

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using Microsoft.CodeAnalysis.CSharp.Syntax;

namespace Gir.Integration.CSharp;

internal static class SyntaxHelper
{
    #region Methods

    public static AttributeSyntax GetAttributeSyntax(MemberDeclarationSyntax member, string attributeName)
    {
        if (!TryGetAttributeSyntax(member, attributeName, out var attributeSyntax))
            throw new Exception($"Attribute {attributeName} not found.");

        return attributeSyntax;
    }

    public static bool TryGetAttributeSyntax(MemberDeclarationSyntax member, string attributeName, [NotNullWhen(true)] out AttributeSyntax? attributeSyntax)
    {
        var attributes = member.AttributeLists.SelectMany(x => x.Attributes);
        attributeSyntax = attributes.FirstOrDefault(x => x.Name.ToString() == attributeName);

        return attributeSyntax is not null;
    }

    public static string GetFirstArgument(AttributeSyntax attribute)
    {
        if (attribute.ArgumentList is null)
            throw new Exception($"Attribute does not contain an argument");

        return attribute.ArgumentList.Arguments.First().ToString();
    }

    public static IEnumerable<FieldDeclarationSyntax> GetFieldSyntaxes(ClassDeclarationSyntax classDeclarationSyntax)
    {
        return classDeclarationSyntax.Members.Where(x => x is FieldDeclarationSyntax).Cast<FieldDeclarationSyntax>();
    }

    public static bool HasAttribute(MemberDeclarationSyntax memberSyntax, string attribute)
    {
        return TryGetAttributeSyntax(memberSyntax, attribute, out _);
    }

    public static string GetFirstFieldName(FieldDeclarationSyntax field)
    {
        return field.Declaration.Variables.First().Identifier.ValueText;
    }

    #endregion
}