Trimming strings, /emacs/lisp/emacs-lisp/subr-x.el modification

[Jean-Christophe Helary <jean.christophe.helary@gmail.com>]

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Following the discussion about how trimming in subr-x.el did not allow for non-default regex, I have this small modification to the 3 trimming functions found therein.

Basically:
1) I extracted the default regex and assigned it to string-trim-default-regex
2) I declared optional "trim-left" and "trim-right" arguments respectively for the string-trim-left and string-trim-right functions, and declared both optional for the general string-trim function

The documentation strings are pretty much taken from subr.el so maybe the wording is not the best.

Please advise.

Jean-Christophe


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diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el
index 440213eb38..188f314871 100644
--- a/lisp/emacs-lisp/subr-x.el
+++ b/lisp/emacs-lisp/subr-x.el
@@ -179,21 +179,36 @@ VARLIST can just be a plain tuple.
 
 (define-obsolete-function-alias 'string-reverse 'reverse "25.1")
 
-(defsubst string-trim-left (string)
-  "Remove leading whitespace from STRING."
-  (if (string-match "\\`[ \t\n\r]+" string)
+(defconst string-trim-default-regex "[ \t\n\r]+")
+  "The default value of separators for `string-trim'."
+
+(defsubst string-trim-left (string &optional trim-left)
+  "Trim STRING of leading whitespace matching TRIM-LEFT.
+
+If TRIM-LEFT is non-nil, it should be a regular expression. If nil,
+it defaults to `string-trim-default-regex', normally \"[ \t\n\r]+\"."
+  
+  (if (string-match (concat "\\`" (or  trim-left string-trim-default-regex)) string)
       (replace-match "" t t string)
     string))
 
-(defsubst string-trim-right (string)
-  "Remove trailing whitespace from STRING."
-  (if (string-match "[ \t\n\r]+\\'" string)
+(defsubst string-trim-right (string &optional trim-right)
+  "Trim STRING of trailing whitespace matching TRIM-RIGHT.
+
+If TRIM-RIGHT is non-nil, it should be a regular expression. If nil,
+it defaults to `string-trim-default-regex', normally \"[ \t\n\r]+\"."
+  
+  (if (string-match (concat (or trim-right string-trim-default-regex) "\\'") string)
       (replace-match "" t t string)
     string))
 
-(defsubst string-trim (string)
-  "Remove leading and trailing whitespace from STRING."
-  (string-trim-left (string-trim-right string)))
+(defsubst string-trim (string &optional trim-left trim-right)
+  "Trim STRING of leading and trailing whitespace matching TRIM-LEFT and TRIM-RIGHT.
+
+If TRIM-LEFT and TRIM-RIGHT are non-nil, they should be a regular expression. If nil,
+they default to `string-trim-default-regex', normally \"[ \t\n\r]+\"."
+
+  (string-trim-left (string-trim-right string trim-right) trim-left))
 
 (defsubst string-blank-p (string)
   "Check whether STRING is either empty or only whitespace."