lisp - 如何在拆分字符串后修剪以在 Lisp 中列出

Question

以下代码来自 https://www.rosettacode.org/wiki/Tokenize_a_string#Common_Lisp在逗号处拆分字符串并发送列表。

(defun comma-split (string)
  (loop for start = 0 then (1+ finish)
        for finish = (position #\, string :start start)
        collecting (subseq string start finish)
        until (null finish)
  )
)

但是，如果子字符串在原始字符串中，则子字符串周围会有空格。

> (comma-split " a, b ,c , d ,   e")
(" a" " b " "c " " d " "   e")

如何在此处添加字符串修剪功能以删除这些空格。我看不到函数中返回的字符串变量。

我尝试使用局部变量，但它不起作用:

(defun comma-split2 (string)
(let* ( (onestr "")
     ) 
  (loop for start = 0 then (1+ finish)
        for finish = (position #\, string :start start)
        (onestr (subseq string start finish))
        (onestr (string-trim onestr))
        collecting onestr
        until (null finish)
  )
))

加载文件时出错:

*** - LOOP: illegal syntax near (ONESTR (SUBSEQ STRING START FINISH)) in
       (LOOP FOR START = 0 THEN (1+ FINISH) FOR FINISH = (POSITION #\, STRING :START START) (ONESTR (SUBSEQ STRING START FINISH))
        (ONESTR (STRING-TRIM ONESTR)) COLLECTING ONESTR UNTIL (NULL FINISH))
The following restarts are available:

即使在第二个函数中修剪 outlist 也不起作用:

(defun comma-split2 (string)
(let ( (outlist (list))
    (setf outlist (comma-split string))
    (dolist (str outlist)
        (push (string-trim str) outlist)
    )
    (nreverse outlist)
)))

> (comma-split2 " a, b ,c , d ,   e")

*** - LET: illegal variable specification (SETF OUTLIST (COMMA-SPLIT STRING))
The following restarts are available:

Answer 1

COLLECTING 语句是创建列表的内容。因此，您需要围绕正在收集的内容调用 STRING-TRIM。

(defun comma-split (string)
  (loop for start = 0 then (1+ finish)
        for finish = (position #\, string :start start)
        collecting (string-trim " " (subseq string start finish))
        until (null finish)))

您不应该将右括号单独放在一行。