Clojure - 编写 split-first 和 split-last 的惯用方式

Question

编写以下函数的惯用方式是什么？

(split-first #"." "abc.def.ghi") ;;=>["abc", "def.ghi"]
(split-last #"." "abc.def.ghi") ;;=>["abc.def", "ghi"]

使用 split 有一个明显(丑陋？)的解决方案，但我确定还有更优雅的解决方案？也许使用 regexes/indexOf/split-with？

Answer 1

对于优先拆分，最好的方法是:

(defn split-first [re s]
  (clojure.string/split s re 2))

(split-first #"\." "abc.def.ghi") 
=> ["abc" "def.ghi"]

(split-first #"<>" "abc<>def<>ghi")
=> ["abc" "def<>ghi"]

split-last 的一种方法是使用否定先行断言:

(defn split-last [re s]
  (let [pattern (re-pattern (str re "(?!.*" re ")"))]
    (split-first pattern s)))

(split-last #"\." "abc.def.ghi")
=> ["abc.def" "ghi"]

(split-last #"<>" "abc<>def<>ghi")
=> ["abc<>def" "ghi"]