From: Chris Hanson <org/chris-hanson/cph>
Date: Tue, 23 May 2000 21:48:53 +0000 (+0000)
Subject: Do pivoting when deciding what a two-digit year means.  I can't
X-Git-Tag: 20090517-FFI~3691
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=9ac3e0dbb04a32e20c8dbee9fa94e98b9395b913;p=mit-scheme.git

Do pivoting when deciding what a two-digit year means.  I can't
believe that some programs still generate these strings!
---

diff --git a/v7/src/runtime/datime.scm b/v7/src/runtime/datime.scm
index cc3a083d6..ccf21757f 100644
--- a/v7/src/runtime/datime.scm
+++ b/v7/src/runtime/datime.scm
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Id: datime.scm,v 14.28 2000/05/15 18:15:36 cph Exp $
+$Id: datime.scm,v 14.29 2000/05/23 21:48:53 cph Exp $
 
 Copyright (c) 1988-2000 Massachusetts Institute of Technology
 
@@ -253,11 +253,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 			   (string->number (car time))
 			   (string->number (list-ref tokens 0))
 			   (string->month (list-ref tokens 1))
-			   (let ((n (string->number (list-ref tokens 2))))
-			     (and (exact-nonnegative-integer? n)
-				  (if (< n 100)
-				      (+ 1900 n)
-				      n)))
+			   (string->year (list-ref tokens 2))
 			   (string->time-zone (list-ref tokens 4)))))))
 
 (define (string->universal-time string)
@@ -343,12 +339,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 			   (string->number (car time))
 			   (string->number (list-ref tokens 2))
 			   (string->month (list-ref tokens 1))
-			   (let ((n (string->number (list-ref tokens 4))))
-			     (if (not (exact-nonnegative-integer? n))
-				 (lose))
-			     (if (< n 100)
-				 (+ 1900 n)
-				 n))
+			   (string->year (list-ref tokens 4))
 			   zone)))))
 
 (define (universal-time->local-ctime-string time)
@@ -434,6 +425,14 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 	    ((string-ci=? string (vector-ref string-vector index)) index)
 	    (else (loop (fix:+ index 1)))))))
 
+(define (string->year string)
+  (let ((n (string->number string)))
+    (if (not (exact-nonnegative-integer? n))
+	(error:bad-range-argument string 'STRING->YEAR))
+    (cond ((< n 38) (+ 2000 n))
+	  ((< n 100) (+ 1900 n))
+	  (else n))))
+
 ;; Upwards compatibility
 (define decode-universal-time universal-time->local-decoded-time)
 (define encode-universal-time decoded-time->universal-time)