emacs 正则表达式问题

Question

我在使用以下代码时遇到问题，不确定我还能如何编写它

(defun padname (strg)
  (string-match "[uU]_\(.*\)\(_[0-9\]+\)?" strg)
    (match-string 1 strg)
)

(padname "u_CLR_REQ_SUP_00")
"CLR_REQ_SUP_00" ==> expect "CLR_REQ_SUP"
(padname "u_CLR_REQ_SUP_0")
"CLR_REQ_SUP_0"  ==> expect "CLR_REQ_SUP"
(padname "u_PTO_AVDD_3P3_0")
"PTO_AVDD_3P3_0"  ==> expect "PTO_AVDD_3P3"
(padname "u_PTO_0")
"PTO_0"  ==> expect "PTO"
(padname "u_PTO")
"PTO" ==> as expected
(padname "u_BTNI")
"BTNI" ==> as expected

Answer 1

你可以让第一组非贪婪，并在第二个可选组之后添加一个锚点

[Uu]_\(.*?\)\(_[0-9]+\)?$

Answer 2

另一种变体，在末尾使用带有[^0-9_][0-9]*的贪婪点来停止在最后一个非数字后面有任何数字并与可选组组合：

[Uu]_\(.*[^0-9_][0-9]*\)\(_[0-9]+\)?$

见regex proof。

解释

--------------------------------------------------------------------------------
  [Uu]                     any character of: 'U', 'u'
--------------------------------------------------------------------------------
  _                        '_'
--------------------------------------------------------------------------------
  (                        group and capture to :
--------------------------------------------------------------------------------
    .*                       any character except \n (0 or more times
                             (matching the most amount possible))
--------------------------------------------------------------------------------
    [^0-9_]                  any character except: '0' to '9', '_'
--------------------------------------------------------------------------------
    [0-9]*                   any character of: '0' to '9' (0 or more
                             times (matching the most amount
                             possible))
--------------------------------------------------------------------------------
  )                        end of 
--------------------------------------------------------------------------------
  (                        group and capture to  (optional
                           (matching the most amount possible)):
--------------------------------------------------------------------------------
    _                        '_'
--------------------------------------------------------------------------------
    [0-9]+                   any character of: '0' to '9' (1 or more
                             times (matching the most amount
                             possible))
--------------------------------------------------------------------------------
  )?                       end of  (NOTE: because you are using a
                           quantifier on this capture, only the LAST
                           repetition of the captured pattern will be
                           stored in )
--------------------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string

emacs 正则表达式问题

Issue with emacs regular expression

regex

emacs

elisp