比较两个相同结构的任意JToken-s

Question

提前致谢.我感谢任何帮助.

我想比较两个相同类型和结构的任意JTokens(来自NewtonSoft的Json.Net).

static int CompareTokens(JToken x, JToken y);  
// possible output: 0 / 1 / -1

主要目标是能够使用此方法对两个Json字符串进行排序,这样即使在开始时它们具有相同的数据,但是以不同的顺序,最后这两个字符串完全相同.所以排序标准并不重要,重要的是这个标准总是一样的.并且应该考虑每个小数据元素.

JToken可以是以下几种类型之一:Array, Boolean, Date, Float, Guid, Integer, Null, Object, Property, String, TimeSpan, Uri.我不考虑比较Bytes, Comment, Constructor, None, Undefined, Raw.

• 获得一些关于比较JArrays和JObjects的想法会很棒.这应该是一些递归比较,因为JArrays可能包含其他JArrays和JObject,反之亦然.任何想法将不胜感激.
• 但是,了解比较更简单的类型也会非常有帮助.我想知道如何从JToken转换为实际类型(而不是知道如何逻辑地执行它).
• JValue已实现IComparable,但我没有弄清楚如何将简单类型的JToken转换为JValue.了解这一点也会有所帮助.

这是一个很常见的问题.如果我弄明白该怎么做,我会给它加一个+100.抱歉我的英语.

Answer 1

在Linq-to-JSON中,JValue表示原始值(字符串,数字,布尔值等).它实现了IComparable<JValue>,所以Json.NET负责为你排序原始值.

基于此,您将需要以递归方式JToken并行地下降两个对象层次结构.当您遇到具有不同.Net类型的第一个令牌,或不同的属性(如果不是a JValue)或具有不同的值(如果是JValue)时,您需要返回比较值.

请记住以下内容:

• 比较方法应该是反身的,反对称的和传递的.
• 不同.Net类型的容器令牌需要以某种一致的方式按类型排序.
• 儿童代币JArray和JConstructor订购.
• 儿童代币JObject不是,所以需要以一种稳定,对称的方式进行比较.按照属性名称行走似乎都有效.
• 没有明显的比较方法JRaw,所以不要尝试,并抛出异常.

以下是原型实现:

public class JTokenComparer : IComparer<JToken>
{
    public static JTokenComparer Instance { get { return instance; } }

    static JTokenComparer instance;

    static JTokenComparer()
    {
        instance = new JTokenComparer();
    }

    readonly Dictionary<Type, KeyValuePair<int, IComparer<JToken>>> dict;

    JTokenComparer()
    {
        dict = new Dictionary<Type, KeyValuePair<int, IComparer<JToken>>>
        {
            // Order chosen semi-arbitrarily.  Putting values first seems reasonable though.
            {typeof(JValue), new KeyValuePair<int, IComparer<JToken>>(0, new JValueComparer()) },
            {typeof(JProperty), new KeyValuePair<int, IComparer<JToken>>(1, new JPropertyComparer()) },
            {typeof(JArray), new KeyValuePair<int, IComparer<JToken>>(2, new JArrayComparer()) },
            {typeof(JObject), new KeyValuePair<int, IComparer<JToken>>(3, new JObjectComparer()) },
            {typeof(JConstructor), new KeyValuePair<int, IComparer<JToken>>(4, new JConstructorComparer()) },
        };
    }

    #region IComparer<JToken> Members

    public int Compare(JToken x, JToken y)
    {
        if (x is JRaw || y is JRaw)
            throw new InvalidOperationException("Tokens of type JRaw cannot be sorted");
        if (object.ReferenceEquals(x, y))
            return 0;
        else if (x == null)
            return -1;
        else if (y == null)
            return 1;

        var typeData1 = dict[x.GetType()];
        var typeData2 = dict[y.GetType()];

        int comp;
        if ((comp = typeData1.Key.CompareTo(typeData2.Key)) != 0)
            return comp;
        if (typeData1.Value != typeData2.Value)
            throw new InvalidOperationException("inconsistent dictionary values"); // Internal error
        return typeData2.Value.Compare(x, y);
    }

    #endregion
}

abstract class JTokenComparerBase<TJToken> : IComparer<JToken> where TJToken : JToken
{
    protected TJToken CheckType(JToken item)
    {
        if (item != null && item.GetType() != typeof(TJToken))
            throw new ArgumentException(string.Format("Actual type {0} of token \"{1}\" does not match expected type {2}", item.GetType(), item, typeof(TJToken)));
        return (TJToken)item;
    }

    protected bool TryBaseCompare(TJToken x, TJToken y, out int comparison)
    {
        CheckType(x);
        CheckType(y);
        if (object.ReferenceEquals(x, y))
        {
            comparison = 0;
            return true;
        }
        else if (x == null)
        {
            comparison = -1;
            return true;
        }
        else if (y == null)
        {
            comparison = 1;
            return true;
        }
        comparison = 0;
        return false;
    }

    protected abstract int CompareDerived(TJToken x, TJToken y);

    protected int TokenCompare(JToken x, JToken y)
    {
        var tx = CheckType(x);
        var ty = CheckType(y);
        int comp;
        if (TryBaseCompare(tx, ty, out comp))
            return comp;
        return CompareDerived(tx, ty);
    }

    #region IComparer<JToken> Members

    int IComparer<JToken>.Compare(JToken x, JToken y)
    {
        return TokenCompare(x, y);
    }

    #endregion
}

abstract class JContainerOrderedComparerBase<TJToken> : JTokenComparerBase<TJToken> where TJToken : JContainer
{
    protected int CompareItemsInOrder(TJToken x, TJToken y)
    {
        int comp;
        // Dictionary order: sort on items before number of items.
        for (int i = 0, n = Math.Min(x.Count, y.Count); i < n; i++)
            if ((comp = JTokenComparer.Instance.Compare(x[i], y[i])) != 0)
                return comp;
        if ((comp = x.Count.CompareTo(y.Count)) != 0)
            return comp;
        return 0;
    }
}

class JPropertyComparer : JTokenComparerBase<JProperty>
{
    protected override int CompareDerived(JProperty x, JProperty y)
    {
        int comp;
        if ((comp = x.Name.CompareTo(y.Name)) != 0)
            return comp;
        return JTokenComparer.Instance.Compare(x.Value, y.Value);
    }
}

class JObjectComparer : JTokenComparerBase<JObject>
{
    protected override int CompareDerived(JObject x, JObject y)
    {
        int comp;
        // Dictionary order: sort on items before number of items.
        // Order both property sequences to preserve reflexivity.
        foreach (var propertyComp in x.Properties().OrderBy(p => p.Name).Zip(y.Properties().OrderBy(p => p.Name), (xp, yp) => JTokenComparer.Instance.Compare(xp, yp)))
            if (propertyComp != 0)
                return propertyComp;
        if ((comp = x.Count.CompareTo(y.Count)) != 0)
            return comp;
        return 0;
    }
}

class JArrayComparer : JContainerOrderedComparerBase<JArray>
{
    protected override int CompareDerived(JArray x, JArray y)
    {
        int comp;
        if ((comp = CompareItemsInOrder(x, y)) != 0)
            return comp;
        return 0;
    }
}

class JConstructorComparer : JContainerOrderedComparerBase<JConstructor>
{
    protected override int CompareDerived(JConstructor x, JConstructor y)
    {
        int comp;
        if ((comp = x.Name.CompareTo(y.Name)) != 0)
            return comp;
        if ((comp = CompareItemsInOrder(x, y)) != 0)
            return comp;
        return 0;
    }
}

class JValueComparer : JTokenComparerBase<JValue>
{
    protected override int CompareDerived(JValue x, JValue y)
    {
        return Comparer<JToken>.Default.Compare(x, y); // JValue implements IComparable<JValue>
    }
}

经过轻微测试的原型小提琴.

Answer 2

实际上，这可以用更少的代码来完成。不太好，因为使用字符串比较而不是JValue比较。

以下不是我自己问题的确切答案，但目标已经达到。

    public static JToken Normalize(this JToken token)
    {
        var result = token;

        switch (token.Type)
        {
            case JTokenType.Object:
                var jObject = (JObject)token;

                if (jObject != null && jObject.HasValues)
                {
                    var newObject = new JObject();

                    foreach (var property in jObject.Properties().OrderBy(x => x.Name).ToList())
                    {
                        var value = property.Value as JToken;
                        if (value != null)
                        {
                            value = Normalize(value);
                        }

                        newObject.Add(property.Name, value);
                    }
                    return newObject;
                }

                break;

            case JTokenType.Array:

                var jArray = (JArray)token;

                if (jArray != null && jArray.Count > 0)
                {
                    var normalizedArrayItems = jArray
                        .Select(x => Normalize(x))
                        .OrderBy(x => x.ToString(), StringComparer.Ordinal);

                    result = new JArray(normalizedArrayItems);
                }

                break;
            default:
                break;
        }

        return result;
    }