mirror of
https://github.com/GeWuYou/GFramework.git
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1d50dc2224
- 在Combine方法中添加对Bottom状态的检查和处理 - 使用IfSucc方法简化成功状态下的值添加逻辑 - 修正泛型绑定示例中的语法错误 - 在FromNullable和FromNullableStruct方法中使用nameof获取参数名称 - 改进Exception属性的文档说明并优化异常消息 - 在Try方法中添加对空函数的验证
411 lines
13 KiB
C#
411 lines
13 KiB
C#
// Copyright (c) 2025 GeWuYou
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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using System.Diagnostics.Contracts;
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namespace GFramework.Core.Functional;
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/// <summary>
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/// 表示一个操作的结果，可能是成功值或异常
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/// </summary>
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public readonly struct Result<A> : IEquatable<Result<A>>, IComparable<Result<A>>
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{
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private readonly A? _value;
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private readonly Exception? _exception;
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// ------------------------------------------------------------------ 状态枚举
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/// <summary>
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/// 结果状态枚举，表示结果的不同状态
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/// 排序: Bottom < Faulted < Success
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/// </summary>
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private enum ResultState : byte
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{
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Bottom,
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Faulted,
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Success
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}
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private readonly ResultState _state;
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// ------------------------------------------------------------------ 静态默认值
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/// <summary>
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/// 表示未初始化的 Bottom 状态
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/// </summary>
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public static readonly Result<A> Bottom = default;
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// ------------------------------------------------------------------ 构造器
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/// <summary>
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/// 构造成功结果
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/// </summary>
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/// <param name="value">成功的值</param>
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public Result(A value)
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{
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_state = ResultState.Success;
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_value = value;
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_exception = null;
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}
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/// <summary>
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/// 构造失败结果
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/// </summary>
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/// <param name="exception">失败的异常</param>
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public Result(Exception exception)
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{
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_state = ResultState.Faulted;
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_exception = exception ?? throw new ArgumentNullException(nameof(exception));
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_value = default;
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}
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// ------------------------------------------------------------------ 隐式转换
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/// <summary>
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/// 隐式将值转换为成功结果
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/// </summary>
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/// <param name="value">要转换的值</param>
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/// <returns>成功结果</returns>
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[Pure]
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public static implicit operator Result<A>(A value) => new(value);
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// ------------------------------------------------------------------ 状态属性
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/// <summary>
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/// 判断结果是否为成功状态
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/// </summary>
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[Pure]
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public bool IsSuccess => _state == ResultState.Success;
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/// <summary>
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/// 判断结果是否为失败状态
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/// </summary>
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[Pure]
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public bool IsFaulted => _state == ResultState.Faulted;
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/// <summary>
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/// 判断结果是否为未初始化的 Bottom 状态
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/// </summary>
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[Pure]
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public bool IsBottom => _state == ResultState.Bottom;
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/// <summary>
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/// 获取内部异常：
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/// - 若为 Failure 状态，则返回内部异常
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/// - 若为 Bottom 状态，则返回带有 "Result is in Bottom state." 消息的 InvalidOperationException
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/// - 若为 Success 状态，则返回带有 "Cannot access Exception on a successful Result." 消息的 InvalidOperationException
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/// </summary>
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[Pure]
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public Exception Exception => _exception
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?? (IsBottom
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? new InvalidOperationException("Result is in Bottom state.")
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: new InvalidOperationException(
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"Cannot access Exception on a successful Result."));
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// ------------------------------------------------------------------ 取值
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/// <summary>
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/// 若成功则返回值，若失败则返回默认值
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/// </summary>
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/// <param name="defaultValue">失败时返回的默认值</param>
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/// <returns>成功时的值或默认值</returns>
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[Pure]
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public A IfFail(A defaultValue) => IsSuccess ? _value! : defaultValue;
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/// <summary>
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/// 若成功则返回值，若失败则通过委托处理异常
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/// </summary>
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/// <param name="f">处理异常的委托</param>
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/// <returns>成功时的值或委托处理后的结果</returns>
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[Pure]
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public A IfFail(Func<Exception, A> f) => IsSuccess ? _value! : f(Exception);
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/// <summary>
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/// 若失败则执行副作用
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/// </summary>
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/// <param name="f">处理异常的副作用委托</param>
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public void IfFail(Action<Exception> f)
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{
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if (IsFaulted) f(Exception);
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}
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/// <summary>
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/// 若成功则执行副作用
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/// </summary>
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/// <param name="f">处理成功值的副作用委托</param>
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public void IfSucc(Action<A> f)
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{
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if (IsSuccess) f(_value!);
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}
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// ------------------------------------------------------------------ 变换
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/// <summary>
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/// 成功时映射值，失败时透传异常
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/// </summary>
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/// <typeparam name="B">映射后的类型</typeparam>
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/// <param name="f">映射函数</param>
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/// <returns>映射后的结果</returns>
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[Pure]
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public Result<B> Map<B>(Func<A, B> f)
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{
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ArgumentNullException.ThrowIfNull(f);
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return IsSuccess ? new Result<B>(f(_value!)) : new Result<B>(Exception);
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}
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/// <summary>
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/// 成功时绑定到新 Result，失败时透传异常
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/// </summary>
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/// <typeparam name="B">绑定后的类型</typeparam>
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/// <param name="binder">绑定函数</param>
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/// <returns>绑定后的结果</returns>
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[Pure]
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public Result<B> Bind<B>(Func<A, Result<B>> binder)
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{
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ArgumentNullException.ThrowIfNull(binder);
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return IsSuccess ? binder(_value!) : new Result<B>(Exception);
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}
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/// <summary>
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/// 异步映射
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/// </summary>
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/// <typeparam name="B">映射后的类型</typeparam>
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/// <param name="f">异步映射函数</param>
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/// <returns>异步映射后的结果</returns>
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[Pure]
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public async Task<Result<B>> MapAsync<B>(Func<A, Task<B>> f)
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{
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ArgumentNullException.ThrowIfNull(f);
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if (!IsSuccess) return new Result<B>(Exception);
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try
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{
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return new Result<B>(await f(_value!));
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}
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catch (Exception ex)
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{
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return new Result<B>(ex);
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}
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}
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// ------------------------------------------------------------------ 模式匹配
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/// <summary>
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/// 对成功/失败两种情况分别处理并返回值
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/// </summary>
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/// <typeparam name="R">返回值类型</typeparam>
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/// <param name="succ">处理成功值的函数</param>
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/// <param name="fail">处理异常的函数</param>
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/// <returns>处理后的结果</returns>
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[Pure]
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public R Match<R>(Func<A, R> succ, Func<Exception, R> fail) =>
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IsSuccess ? succ(_value!) : fail(Exception);
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/// <summary>
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/// 对成功/失败两种情况分别执行副作用
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/// </summary>
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/// <param name="succ">处理成功值的副作用委托</param>
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/// <param name="fail">处理异常的副作用委托</param>
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public void Match(Action<A> succ, Action<Exception> fail)
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{
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if (IsSuccess) succ(_value!);
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else fail(Exception);
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}
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// ------------------------------------------------------------------ 静态工厂（语义更清晰）
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/// <summary>
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/// 创建成功结果
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/// </summary>
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/// <param name="value">成功的值</param>
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/// <returns>成功结果</returns>
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[Pure]
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public static Result<A> Succeed(A value) => new(value);
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/// <summary>
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/// 创建成功结果（别名）
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/// </summary>
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/// <param name="value">成功的值</param>
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/// <returns>成功结果</returns>
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[Pure]
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public static Result<A> Success(A value) => new(value);
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/// <summary>
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/// 创建失败结果
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/// </summary>
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/// <param name="ex">失败的异常</param>
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/// <returns>失败结果</returns>
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[Pure]
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public static Result<A> Fail(Exception ex) => new(ex);
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/// <summary>
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/// 创建失败结果（别名）
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/// </summary>
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/// <param name="ex">失败的异常</param>
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/// <returns>失败结果</returns>
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[Pure]
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public static Result<A> Failure(Exception ex) => new(ex);
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/// <summary>
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/// 根据错误消息创建失败结果
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/// </summary>
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/// <param name="message">错误消息</param>
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/// <returns>失败结果</returns>
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[Pure]
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public static Result<A> Failure(string message) => new(new Exception(message));
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/// <summary>
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/// 安全执行委托，自动捕获异常
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/// </summary>
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/// <param name="f">要执行的委托</param>
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/// <returns>执行结果</returns>
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public static Result<A> Try(Func<A> f)
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{
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ArgumentNullException.ThrowIfNull(f);
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try
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{
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return new Result<A>(f());
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}
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catch (Exception ex)
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{
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return new Result<A>(ex);
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}
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}
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// ------------------------------------------------------------------ 相等 / 比较
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/// <summary>
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/// 判断两个结果是否相等
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/// </summary>
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/// <param name="other">另一个结果</param>
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/// <returns>若相等返回 true，否则返回 false</returns>
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[Pure]
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public bool Equals(Result<A> other)
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{
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if (_state != other._state) return false;
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if (IsSuccess) return EqualityComparer<A>.Default.Equals(_value, other._value);
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if (IsFaulted)
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return Exception.GetType() == other.Exception.GetType()
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&& Exception.Message == other.Exception.Message;
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return true; // both Bottom
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}
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/// <summary>
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/// 判断对象是否与当前结果相等
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/// </summary>
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/// <param name="obj">要比较的对象</param>
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/// <returns>若相等返回 true，否则返回 false</returns>
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[Pure]
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public override bool Equals(object? obj) => obj is Result<A> other && Equals(other);
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/// <summary>
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/// 获取结果的哈希码
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/// </summary>
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/// <returns>哈希码</returns>
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[Pure]
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public override int GetHashCode() => IsSuccess
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? HashCode.Combine(0, _value)
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: HashCode.Combine(1, Exception.GetType(), Exception.Message);
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/// <summary>
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/// 比较两个结果的大小
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/// </summary>
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/// <param name="other">另一个结果</param>
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/// <returns>比较结果</returns>
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[Pure]
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public int CompareTo(Result<A> other)
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{
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// Bottom < Faulted < Success
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if (_state != other._state) return _state.CompareTo(other._state);
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if (!IsSuccess) return 0;
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try
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{
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return Comparer<A>.Default.Compare(_value, other._value);
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}
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catch (ArgumentException)
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{
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// 类型不可比较时返回 0
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return 0;
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}
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}
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/// <summary>
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/// 判断两个结果是否相等
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/// </summary>
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/// <param name="a">第一个结果</param>
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/// <param name="b">第二个结果</param>
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/// <returns>若相等返回 true，否则返回 false</returns>
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[Pure]
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public static bool operator ==(Result<A> a, Result<A> b) => a.Equals(b);
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/// <summary>
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/// 判断两个结果是否不相等
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/// </summary>
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/// <param name="a">第一个结果</param>
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/// <param name="b">第二个结果</param>
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/// <returns>若不相等返回 true，否则返回 false</returns>
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[Pure]
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public static bool operator !=(Result<A> a, Result<A> b) => !a.Equals(b);
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/// <summary>
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/// 判断第一个结果是否小于第二个结果
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/// </summary>
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/// <param name="a">第一个结果</param>
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/// <param name="b">第二个结果</param>
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/// <returns>若小于返回 true，否则返回 false</returns>
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[Pure]
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public static bool operator <(Result<A> a, Result<A> b) => a.CompareTo(b) < 0;
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/// <summary>
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/// 判断第一个结果是否小于等于第二个结果
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/// </summary>
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/// <param name="a">第一个结果</param>
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/// <param name="b">第二个结果</param>
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/// <returns>若小于等于返回 true，否则返回 false</returns>
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[Pure]
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public static bool operator <=(Result<A> a, Result<A> b) => a.CompareTo(b) <= 0;
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/// <summary>
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/// 判断第一个结果是否大于第二个结果
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/// </summary>
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/// <param name="a">第一个结果</param>
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/// <param name="b">第二个结果</param>
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/// <returns>若大于返回 true，否则返回 false</returns>
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[Pure]
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public static bool operator >(Result<A> a, Result<A> b) => a.CompareTo(b) > 0;
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/// <summary>
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/// 判断第一个结果是否大于等于第二个结果
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/// </summary>
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/// <param name="a">第一个结果</param>
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/// <param name="b">第二个结果</param>
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/// <returns>若大于等于返回 true，否则返回 false</returns>
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[Pure]
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public static bool operator >=(Result<A> a, Result<A> b) => a.CompareTo(b) >= 0;
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// ------------------------------------------------------------------ 调试
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/// <summary>
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/// 返回结果的字符串表示
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/// </summary>
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/// <returns>结果的字符串表示</returns>
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[Pure]
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public override string ToString() => _state switch
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{
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ResultState.Success => _value?.ToString() ?? "(null)",
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ResultState.Faulted => $"Fail({Exception.Message})",
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_ => "(Bottom)"
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};
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} |