WorkflowGraphGenerator.cs

public class WorkflowGraphGenerator : Esprima.Utils.AstVisitor
{
    StringBuilder _sb = new StringBuilder();
    Stack<string> _current = new Stack<string>();
    Stack<string> _conditionals = new Stack<string>();
    private string _code;

    public string Graph => _sb.ToString() + "\r\n}";

    public WorkflowGraphGenerator(string code)
    {
        _code = code;
        _sb.AppendLine("digraph G {");
    }

    protected override void VisitIfStatement(Esprima.Ast.IfStatement ifStatement)
    {
        var text = _code.Substring(ifStatement.Test.Range.Start, ifStatement.Test.Range.End - ifStatement.Test.Range.Start);
        _conditionals.Push(
            text.Replace("\"", "\\\"")
            );

        base.VisitIfStatement(ifStatement);

        _conditionals.Pop();
    }

    protected override void VisitReturnStatement(Esprima.Ast.ReturnStatement returnStatement)
    {
        if(returnStatement.Argument is Esprima.Ast.Literal explain)
        {
            _sb.Append($"\"{_current.Peek()}\" -> \"{explain.StringValue}\" ");

            if (_conditionals.Count > 0)
            {
                _sb.Append("[ label=\"").AppendJoin(" AND ", _conditionals).Append("\" ]");
            }

            _sb.AppendLine(";");
        }
        base.VisitReturnStatement(returnStatement);
    }

    protected override void VisitCallExpression(Esprima.Ast.CallExpression callExpression)
    {
        var depth = _current.Count;
        if (callExpression.Callee is Esprima.Ast.Identifier id)
        {
            switch (id.Name)
            {
                case "on":
                    if(callExpression.Arguments.Count > 0 && callExpression.Arguments[0] is Esprima.Ast.Literal onLabel)
                    {
                        _current.Push(onLabel.StringValue);
                    }
                    break;
                case "next":
                    if (callExpression.Arguments.Count > 0 && callExpression.Arguments[0] is Esprima.Ast.Literal nextLabel)
                    {
                        _sb.Append($"\"{_current.Peek()}\" -> \"{nextLabel.StringValue}\" ");

                        if(_conditionals.Count > 0)
                        {
                            _sb.Append("[ label=\"").AppendJoin(" AND ", _conditionals).Append("\" ]");
                        }

                        _sb.AppendLine(";");
                    }
                    break;
                default:
                    break;
            }

        }
        base.VisitCallExpression(callExpression);
        if (depth != _current.Count)
            _current.Pop();
    }
}