Add version-compare and version>? to utils.scm.

* guix/utils.scm (version-compare, version>?): New exported procedures,
  based on version-string>?, which was formerly in gnu-maintenance.scm.

* guix/gnu-maintenance.scm (version-string>?): Removed procedure.
  (latest-release): Use 'version>?' instead of 'version-string>?'.

1 files changed, 20 insertions, 0 deletions

diff --git a/guix/utils.scm b/guix/utils.scm
index 7ab835e7f1..d7c37e37d1 100644
--- a/guix/utils.scm
+++ b/guix/utils.scm
@@ -57,6 +57,8 @@
 
             gnu-triplet->nix-system
             %current-system
+            version-compare
+            version>?
             package-name->name+version))
 
 
@@ -422,6 +424,24 @@ returned by `config.guess'."
   ;; By default, this is equal to (gnu-triplet->nix-system %host-type).
   (make-parameter %system))
 
+(define version-compare
+  (let ((strverscmp
+         (let ((sym (or (dynamic-func "strverscmp" (dynamic-link))
+                        (error "could not find `strverscmp' (from GNU libc)"))))
+           (pointer->procedure int sym (list '* '*)))))
+    (lambda (a b)
+      "Return '> when A denotes a newer version than B,
+'< when A denotes a older version than B,
+or '= when they denote equal versions."
+      (let ((result (strverscmp (string->pointer a) (string->pointer b))))
+        (cond ((positive? result) '>)
+              ((negative? result) '<)
+              (else '=))))))
+
+(define (version>? a b)
+  "Return #t when A denotes a newer version than B."
+  (eq? '> (version-compare a b)))
+
 (define (package-name->name+version name)
   "Given NAME, a package name like \"foo-0.9.1b\", return two values:
 \"foo\" and \"0.9.1b\".  When the version part is unavailable, NAME and