subq（LISP）的簡單問題

Question

我剛開始使用LISP，來自C語言的背景。到目前爲止，儘管它有着令人難以置信的學習曲線（我也是emacs新手），但它很有趣。

無論如何，我在解析來自c源代碼的include語句時遇到了一個愚蠢的問題 - 如果任何人都可以對此進行評論並提出解決方案，那將會有很大幫助。

(defun include-start (line) 
    (search "#include " line)) 

(defun get-include(line) 
    (let ((s (include-start line))) 
    (if (not (eq NIL s)) 
     (subseq line s (length line))))) 

(get-include "#include <stdio.h>") 

我希望最後一行返回

"<stdio.h>" 

但是實際結果是

"#include <stdio.h>" 

有什麼想法？

Answer 1

(defun include-start (line) 
    "returns the string position after the '#include ' directive or nil if none" 
    (let ((search-string "#include ")) 
    (when (search search-string line) 
     (length search-string)))) 

(defun get-include (line) 
    (let ((s (include-start line))) 
    (when s 
     (subseq line s)))) 

Answer 2

我覺得replace-in-string容易得多。

(replace-in-string "#include <stdio.h>" "#include +" "") 
    => "<stdio.h>" 

爲您的代碼，include-start返回比賽開始，顧名思義。您正在尋找include-end這可能是(+ (include-start ....) (length ....))

Answer 3

(defun get-include (s) 
    (subseq s (mismatch "#include " s)))