Import Upstream version 2c3upstream/2c3

1 files changed, 21 insertions, 1 deletions

diff --git a/strsrch.scm b/strsrch.scm
index b25c229..68bcf0e 100644
--- a/strsrch.scm
+++ b/strsrch.scm
@@ -1,6 +1,6 @@
 ;;; "MISCIO" Search for string from port.
 ; Written 1995, 1996 by Oleg Kiselyov (oleg@ponder.csci.unt.edu)
-; Modified 1996, 1997 by A. Jaffer (jaffer@ai.mit.edu)
+; Modified 1996, 1997, 1998 by A. Jaffer (jaffer@ai.mit.edu)
 ;
 ; This code is in the public domain.
 
@@ -121,3 +121,23 @@
 			  (backtrack (+ 1 i) matched-substr-len))))))))
        )
     (match-1st-char)))
+
+(define (string-subst text old new . rest)
+  (define sub
+    (lambda (text)
+      (set! text
+	    (cond ((equal? "" text) text)
+		  ((substring? old text)
+		   => (lambda (idx)
+			(string-append
+			 (substring text 0 idx)
+			 new
+			 (sub (substring
+			       text (+ idx (string-length old))
+			       (string-length text))))))
+		  (else text)))
+      (if (null? rest)
+	  text
+	  (apply string-subst text rest))))
+  (sub text))
+