如何设置复杂 LINQ 表达式的格式

Question

我有一个怪物linq表达：

public static class HeaderOperators
{
    public static IDictionary<string, string> GetValues(IReadOnlyList<string> keys, IHeaderDictionary headers, string defaultValue)
    {
        return keys.Select(x => x.ToLower()).Intersect(headers.Keys.Select(x => x.ToLower()))
            .Select(k => new KeyValuePair<string, string>(k.ToLower(), headers[k.ToLower()]))
            .Union(keys.Select(x => x.ToLower()).Where(k => !headers.Keys.Select(x => x.ToLower()).Contains(k.ToLower())).Select(k => new KeyValuePair<string, string>(k.ToLower(), defaultValue)))
            .ToDictionary(p => p.Key.ToLower(), p => p.Value);
    }
}

是否有任何工具可以很好地格式化它，使其可读？

或者，也许有一种语法更易于管理？

Answer 1

我会将其拆分为更具可读性：

public static class HeaderOperators
{
    public static IDictionary<string, string> GetValues(IReadOnlyList<string> keys, IHeaderDictionary headers, string defaultValue)
    {
        var firstCollection = keys
            .Select(x => x.ToLower()).Intersect(headers.Keys.Select(x => x.ToLower()))
            .Select(k => new KeyValuePair<string, string>(k.ToLower(), headers[k.ToLower()]));
        var secondCollection = keys
            .Select(x => x.ToLower())
            .Where(k => !headers.Keys.Select(x => x.ToLower()).Contains(k.ToLower()))
            .Select(k => new KeyValuePair<string, string>(k.ToLower(), defaultValue));
        return
            firstCollection.Union(secondCollection).ToDictionary(p => p.Key.ToLower(), p => p.Value);
    }
}

Answer 2

由于它比嵌套更链接，所以我只是将其格式化为：

return keys.Select( x => x.ToLower() )
           .Intersect( headers.Keys.Select(x => x.ToLower()) )
           .Select( k => new KeyValuePair<string, string>(k.ToLower(), headers[k.ToLower()]) )
           .Union( keys.Select(x => x.ToLower() )
           .Where( k => !headers.Keys.Select(x => x.ToLower()).Contains(k.ToLower()) )
           .Select( k => new KeyValuePair<string, string>(k.ToLower(), defaultValue)) )
           .ToDictionary( p => p.Key.ToLower(), p => p.Value );

并且...在每行末尾添加注释。