using Convention.RScript.Parser;
using System.Diagnostics.CodeAnalysis;

namespace Convention.RScript.Runner
{
    public class ExitNamespaceRunner : IRSentenceRunner
    {
        [return: MaybeNull]
        public object Run(ExpressionParser parser, RScriptSentence sentence, RScriptContext context)
        {
            // 移除当前命名空间的变量
            foreach (var local in context.CurrentLocalSpaceVariableNames.Peek())
            {
                context.Variables.Remove(local);
                parser.context.Variables.Remove(local);
            }
            // 还原上层命名空间的变量
            foreach (var local in context.CurrentLocalSpaceVariableNames.Peek())
            {
                parser.context.Variables[local] = context.Variables[local].data;
            }
            context.CurrentLocalSpaceVariableNames.Pop();
            // 弹栈
            context.RuntimePointerStack.Pop();
            return null;
        }
    }
}