using CanonSharp.Combinator.Abstractions;

namespace CanonSharp.Combinator.Parsers;

/// <summary>
/// 修改解析器返回结果的解析器基类
/// </summary>
/// <param name="parser">需要修改结果的解析器</param>
/// <typeparam name="TToken">输入流类型</typeparam>
/// <typeparam name="TIntermediate">需要修改结果的解析器</typeparam>
/// <typeparam name="T">最终返回的解析结果</typeparam>
public abstract class ModifiedParser<TToken, TIntermediate, T>(Parser<TToken, TIntermediate> parser) : Parser<TToken, T>
{
    protected abstract ParseResult<TToken, T> Fail<TState>(TState state,
        FailedResult<TToken, TIntermediate> failedResult)
        where TState : IReadState<TToken, TState>;

    protected abstract ParseResult<TToken, T> Succeed<TState>(TState state,
        SuccessfulResult<TToken, TIntermediate> successfulResult)
        where TState : IReadState<TToken, TState>;

    internal override ParseResult<TToken, TResult> Run<TState, TResult>(TState state,
        Func<ParseResult<TToken, T>, ParseResult<TToken, TResult>> continuation)
        => parser.Run(state, result => result.CaseOf(
            success => continuation(Succeed(state, success)),
            failure => continuation(Fail(state, failure))));
}