如何在Clojure中遍历多分支树并收集数据？

Question

我需要将json转换为另一种格式，所以我使用instaparse将json转换为向量列表。

原始json：

[
  {
    "k1": "v1",
    "k2": {
      "k21": "v21",
      "k22": "v22"
    }
  },
  {
    "k4": "v4",
    "k5": "v5",
    "k6": "v6"
  }
]

转换为clojure向量列表：

[:JSON
 [:ARRAY
  [:OBJECT
   [:KEY_VALUE_PAIR [:STRING "\"k1\""] [:STRING "\"v1\""]]
   [:KEY_VALUE_PAIR
    [:STRING "\"k2\""]
    [:OBJECT
     [:KEY_VALUE_PAIR [:STRING "\"k21\""] [:STRING "\"v21\""]]
     [:KEY_VALUE_PAIR [:STRING "\"k22\""] [:STRING "\"v22\""]]]]]
  [:OBJECT
   [:KEY_VALUE_PAIR [:STRING "\"k4\""] [:STRING "\"v4\""]]
   [:KEY_VALUE_PAIR [:STRING "\"k5\""] [:STRING "\"v5\""]]
   [:KEY_VALUE_PAIR [:STRING "\"k6\""] [:STRING "\"v6\""]]]]]

可视化此链接中的树：visualizing tree

我想要这样的格式：

[
  {
    k1: "k1",
    k2: {
      k21: "k2.k21",
      k22: "k2.k22"
    }
  },
  {
    k4: "k4",
    k5: "k5",
    k6: "k6"
  }
]

那么，如何在Clojure中遍历多分支树并收集数据呢？我发现它很少使用tree-seq和walk函数，所以我试着写代码：

(ns clojure.examples.hello
    (:gen-class))
    
(def json-tree [:JSON [:ARRAY [:OBJECT [:KEY_VALUE_PAIR [:STRING "\"k1\""] [:STRING "\"v1\""]] [:KEY_VALUE_PAIR [:STRING "\"k2\""] [:OBJECT [:KEY_VALUE_PAIR [:STRING "\"k21\""] [:STRING "\"v21\""]] [:KEY_VALUE_PAIR [:STRING "\"k22\""] [:STRING "\"v22\""]]]]] [:OBJECT [:KEY_VALUE_PAIR [:STRING "\"k4\""] [:STRING "\"v4\""]] [:KEY_VALUE_PAIR [:STRING "\"k5\""] [:STRING "\"v5\""]] [:KEY_VALUE_PAIR [:STRING "\"k6\""] [:STRING "\"v6\""]]]]])

(defn transform-key [x]
    (-> x
        (clojure.string/replace "\"" "")
        (clojure.string/upper-case)))

(defn transform-value [x]
    (if (= x "") x (str x ".")))

(defn bf3 "return elements in tree, breath-first"
    [[el & children :as tree] path] ;; a tree is a seq of one element,
                     ;; followed by left and right child trees
    (if (nil? el)
        (do)
        (if (= el :JSON)
            (do (print (get (vec children) 0))
                (bf3 (get (vec children) 0) path))
                (if (= el :ARRAY)
                    (let [[first & rest-list] (get (vec children) 0)
                            rest (vec rest-list)]
                        (do (print "[") (bf3 first path) (bf3 rest path) (print "], ")))
                    (if (= el :OBJECT)
                        (let [[_ [_ key] & rest-list] (get (vec children) 0)
                            [rest] (vec rest-list)]
                            (do (print "{") 
                                (print (str (transform-key key) ": "))
                                (print (str "rest====>" rest))
                                (bf3 rest (transform-key key))
                                (print "}, ")))
                        (if (= el :KEY_VALUE_PAIR)
                            (do (print (str (transform-key (get first 1)) ": ")) 
                                (bf3 rest (str (transform-value path) (transform-key (get first 1)))))
                            (print (str "\"" path "\", "))))))))

(bf3 json-tree "")

但这段代码似乎只能遍历一个分支，其余分支则不能遍历。

Answer 1

您绝对应该考虑使用clojure.walk