Question

我想遍历表示打嗝数据结构的矢量树：

[:div {:class "special"} [:btn-grp '("Hello" "Hi")]]

然后我想调度向量的关键字，如果已经为关键字定义了一个多方法，那么它将返回另一组向量，它将替换原始标记。

例如，上述结构将转换为：

[:div {:class "special"} [:div [:button "Hello"] [:button "Hi"]]]

自定义多方法将接收列表（“hello”“hi”）作为参数。然后它将返回包含按钮的div。

如何编写遍历向量的函数，并将表单中的所有其他内容作为参数调度到关键字，然后用返回的表单替换当前表单？

Answer 1

(ns customtags
  (:require [clojure.walk :as walk]))

(def customtags (atom {}))

(defn add-custom-tag [tag f]
  (swap! customtags assoc tag f))

(defn try-transform [[tag & params :as coll]]
  (if-let [f (get @customtags tag)]
    (apply f params)
    coll))

(defmacro defcustomtag [tag params & body]
  `(add-custom-tag ~tag (fn ~params ~@body)))

(defn apply-custom-tags [coll]
  (walk/prewalk
    (fn [x]
      (if (vector? x)
        (try-transform x)
        x)) coll))

使用它：

(require '[customtags :as ct])
(ct/defcustomtag :btn-grp [& coll] (into [:div] (map (fn [x] [:button x]) coll)))
(ct/defcustomtag :button [name] [:input {:type "button" :id name}])

(def data [:div {:class "special"} [:btn-grp "Hello" "Hi"]])

(ct/apply-custom-tags data)
[:div {:class "special"} [:div [:input {:type "button", :id "Hello"}] [:input {:type "button", :id "Hi"}]]]

遍历矢量树

1 个答案: