bug#17814: 24.3.91; better string manipulation in subr-x

[Shigeru Fukaya <shigeru.fukaya@gmail.com>]

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Some string manipulation functions in subr-x have room to optimize.


string-trim-left, string-trim-right -- use `substring' and
`match-beginning/end' instead of `replace-match'.  The formers have
bytecodes and the latter not.

string-trim -- call string-trim-left first would be cost effective.
But, to change the code to trim both sides of the string at once might
be better.

string-remove-suffix -- change the last argument of substring will
shorten the code.


I change the string-trim defined using defun from defsubst, as its
string literal is somewhat big (Actually I suspect most of other
functions would also be better if defined by defun).


Regards,
Shigeru

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--- orig/subr-x.el	2014-03-21 14:34:40.000000000 +0900
+++ ./subr-x.el	2014-06-20 03:43:54.627390700 +0900
@@ -59,18 +59,23 @@
 (defsubst string-trim-left (string)
   "Remove leading whitespace from STRING."
   (if (string-match "\\`[ \t\n\r]+" string)
-      (replace-match "" t t string)
+      (substring string (match-end 0))
     string))
 
 (defsubst string-trim-right (string)
   "Remove trailing whitespace from STRING."
   (if (string-match "[ \t\n\r]+\\'" string)
-      (replace-match "" t t string)
+      (substring string 0 (match-beginning 0))
     string))
 
-(defsubst string-trim (string)
+(defun string-trim (string)
   "Remove leading and trailing whitespace from STRING."
-  (string-trim-left (string-trim-right string)))
+  ;;(string-trim-right (string-trim-left string))
+  (if (string-match (concat "\\`\\(?:[\s\t\n\r]+\\(?1:.*?\\)[\s\t\n\r]*"
+			    "\\|\\(?1:.*?\\)[\s\t\n\r]+\\)\\'")
+		    string)
+      (match-string 1 string)
+    string))
 
 (defsubst string-blank-p (string)
   "Check whether STRING is either empty or only whitespace."
@@ -85,7 +90,7 @@
 (defsubst string-remove-suffix (suffix string)
   "Remove SUFFIX from STRING if present."
   (if (string-suffix-p suffix string)
-      (substring string 0 (- (length string) (length suffix)))
+      (substring string 0 (- (length suffix)))
     string))
 
 (provide 'subr-x)