Question

我需要一个更健壮的字典式结构来获取：

通过提供密钥（默认字典行为）;
提供一个值（不是那么简单）。

此外，我想扩展这种类字典结构的功能，以便键可以与多个值相关联。

通过this讨论，this回答和this other one提供了实施该工具的工具。我决定从BiDictionary（Jon Skeet的答案）中删除“按索引访问”，因为模糊性会比我想要的更频繁（例如，将字符串映射到字符串时）。我想出的字典式“结构”是：

using System.Collections.Generic;

public interface IBiLookup<TLeft, TRight>
{
    IDictionary<TLeft, ICollection<TRight>> LeftToRight { get; }
    IDictionary<TRight, ICollection<TLeft>> RightToLeft { get; }

    bool TryGetByLeft(TLeft left, out ICollection<TRight> rights);
    bool TryGetByRight(TRight right, out ICollection<TLeft> lefts);

    void Add(TLeft left, TRight right);
}

public class BiLookup<TLeft, TRight> : IBiLookup<TLeft, TRight>
{
    public IDictionary<TLeft, ICollection<TRight>> LeftToRight
    {
        get { return this.leftToRight; }
    }
    public IDictionary<TRight, ICollection<TLeft>> RightToLeft
    {
        get { return this.rightToLeft; }
    }

    public bool TryGetByLeft(TLeft left, out ICollection<TRight> rights)
    {
        return LeftToRight.TryGetValue(left, out rights);
    }
    public bool TryGetByRight(TRight right, out ICollection<TLeft> lefts)
    {
        return RightToLeft.TryGetValue(right, out lefts);
    }

    public void Add(TLeft left, TRight right)
    {
        AddLeftToRight(left, right);
        AddRightToLeft(right, left);
    }

    private void AddLeftToRight(TLeft left, TRight right)
    {
        ICollection<TRight> rights;

        // 1) Is there an entry associated with the "left" value?
        // 2) If so, is the "right" value already associated?
        if (!TryGetByLeft(left, out rights))
        {
            // Then we have to add an entry in the leftToRight dictionary.
            rights = new List<TRight> { right };                
        }
        else
        {
            // So there are entries associated with the "left" value.
            // We must verify if the "right" value itself is not there.
            if (((List<TRight>)rights).FindIndex(element => element.Equals(right)) < 0)
            {
                // We don't have that association yet.
                rights.Add(right);
            }
            else
            {
                // The value is already in the list: do nothing.
                return;
            }
        }

        LeftToRight[left] = rights;
    }
    private void AddRightToLeft(TRight right, TLeft left)
    {
        ICollection<TLeft> lefts;

        // 1) Is there an entry associated with the "right" value?
        // 2) If so, is the "left" value already associated?
        if (!TryGetByRight(right, out lefts))
        {
            // Then we have to add an entry in the leftToRight dictionary.
            lefts = new List<TLeft> { left };
        }
        else
        {
            // So there are entries associated with the "right" value.
            // We must verify if the "right" value itself is not there.
            if (((List<TLeft>)lefts).FindIndex(element => element.Equals(left)) < 0)
            {
                // We don't have that association yet.
                lefts.Add(left);
            }
            else
            {
                // The value is already in the list: do nothing.
                return;
            }
        }

        RightToLeft[right] = lefts;
    }

    #region Fields

    private IDictionary<TLeft, ICollection<TRight>> leftToRight = new Dictionary<TLeft, ICollection<TRight>>();
    private IDictionary<TRight, ICollection<TLeft>> rightToLeft = new Dictionary<TRight, ICollection<TLeft>>();

    #endregion
}

我担心将Add（...）方法拆分为两个更具体的方法是一个很好的实现，因为BiLookup类将被广泛使用，并且要记住性能。此外，此线程的目的是讨论接口和类实现是否尽可能好，或者可以对它们进行改进。

如果我将Interface和“deafult”实现同时保存到类库项目中，那么设计是否足以重用？

Answer 1

在没有实际使用它的情况下，无法确定“设计是否足以重复使用”。您需要尝试以几种不同的方式使用您的代码（所有单元测试都算作一个）以查看它是否有意义并鼓励编写可读代码。

如果您没有任何特定要求（性能或其他方面），只需确保代码的单元测试覆盖率良好，所有测试都通过，测试将涵盖您的预期使用方案。

关于代码的注释：强制转换（即((List<TLeft>)lefts)）看起来是不必要的。 FindIndex次调用（使用O（number_of_items）进行线性搜索）不会在性能敏感代码中查看主页。

IBiLookup和Bilookup：键和值“字典”查找

1 个答案: