data-structures - 如何在结构内移动元素(可能使用 zipper )？

Question

我有这样的结构:

 [{"a" {"b" 1 "c" 2} 
   "children" [{"a" {"b" 3 "c" 4} "children" []}]}
  {"a" {"b" 5 "c" 6} "children" []}
  {"a" {"b" 7 "c" 8}
    "children" [{"a" {"b" 9 "c" 10} "children" []} {"a" {"b" 10 "c" 10} "children" []}]}]

我正在尝试编写一种算法来在向量内移动和元素。例如，在最后一个元素中，它有 children 向量:

"children" [{"a" {"b" 9 "c" 10} "children" []} {"a" {"b" 10 "c" 10} "children" []}]

我的函数应该搜索特定的嵌套映射 - 比方说，找到其 b 属性值为 10 的映射。我将找到 {"a"{"b"10 "c"10} "children"[]}。一旦找到它，我需要用向量改变它的位置。我们假设，children 将变成:

 "children" [{"a" {"b" 10 "c" 10} "children" []} {"a" {"b" 9 "c" 10} "children" []}]

使用 Zipper，我能够遍历并定位嵌套 map ，但不确定如何在向量内移动它。

这是我的 zipper 的创建方式:

  (z/zipper #(contains? % "children") #(get % "children")  (fn [_ c] c) data-structure)

Answer 1

作为替代解决方案，使用 specter :

  (def z [
          {"a" {"b" 1 "c" 2}
           "children" [{"a" {"b" 3 "c" 4}
                        "children" []}]}
          {"a" {"b" 5 "c" 6}
           "children" []}
          {"a" {"b" 7 "c" 8}
           "children" [{"a" {"b" 9 "c" 10}
                        "children" []}
                       {"a" {"b" 10 "c" 10}
                        "children" []}]}])


    (transform
      (walker (fn [x]
                (and
                  (vector? x)
                  (some
                    #(= 10
                        (get-in % ["a" "b"]))
                    x))))
      reverse
      z)

返回:

[{"a" {"b" 1, "c" 2}, "children" [{"a" {"b" 3, "c" 4}, "children" []}]}
 {"a" {"b" 5, "c" 6}, "children" []}
 {"a" {"b" 7, "c" 8},
  "children"
  ({"a" {"b" 10, "c" 10}, "children" []}
   {"a" {"b" 9, "c" 10}, "children" []})}]

注释:

1. 步行者一直在行走，所以如果您正在寻找一次性的转换，您应该以某种方式进行调整。我尝试将 FIRST 添加到变换向量中，但即使找到其中一个“b”，它仍然会继续行走。
2. 我尝试使用 collect-one 而不是 get-in，但没有成功。

如果您找到更好的解决方案，请随时编辑它。我对幽灵还是个新手。