using CanonSharp.Combinator.Abstractions;

namespace CanonSharp.Combinator.Results;

/// <summary>
/// 错误类型的失败解析结果
/// </summary>
/// <typeparam name="TToken">输入流的类型</typeparam>
/// <typeparam name="TState">输入流的读取类型</typeparam>
/// <typeparam name="T">实际的结果类型</typeparam>
internal sealed class FailedResultWithError<TToken, TState, T>(TState state) : IFailedResult<TToken, T>
    where TState : IReadState<TToken, TState>
{
    public IReadState<TToken> State => state;

    public string Message => $"Unexpected state: {state}.";

    public IFailedResult<TToken, TNext> Convert<TNext>()
    {
        return new FailedResultWithError<TToken, TState, TNext>(state);
    }

    public override string ToString() => $"Parse failed: {Message}.";
}