From 9008debc54aaa4d65444d5cef85df83455d48d7b Mon Sep 17 00:00:00 2001 From: Chris Marusich Date: Tue, 1 Nov 2016 22:48:11 -0700 Subject: profiles: Extract a procedure for getting relative generation numbers. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * guix/profiles.scm (relative-generation-spec->number): New procedure. * guix/scripts/package.scm (switch-generation-action): Use it. Signed-off-by: Ludovic Courtès --- guix/profiles.scm | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'guix/profiles.scm') diff --git a/guix/profiles.scm b/guix/profiles.scm index 96f8b65c3e..33a5f50a53 100644 --- a/guix/profiles.scm +++ b/guix/profiles.scm @@ -5,6 +5,7 @@ ;;; Copyright © 2015 Mark H Weaver ;;; Copyright © 2015 Sou Bunnbu ;;; Copyright © 2016 Ricardo Wurmus +;;; Copyright © 2016 Chris Marusich ;;; ;;; This file is part of GNU Guix. ;;; @@ -97,6 +98,7 @@ generation-number generation-numbers profile-generations + relative-generation-spec->number relative-generation previous-generation-number generation-time @@ -1039,6 +1041,23 @@ former profiles were found." '() generations))) +(define (relative-generation-spec->number profile spec) + "Return PROFILE's generation specified by SPEC, which is a string. The SPEC +may be a N, -N, or +N, where N is a number. If the spec is N, then the number +returned is N. If it is -N, then the number returned is the profile's current +generation number minus N. If it is +N, then the number returned is the +profile's current generation number plus N. Return #f if there is no such +generation." + (let ((number (string->number spec))) + (and number + (case (string-ref spec 0) + ((#\+ #\-) + (relative-generation profile number)) + (else (if (memv number (profile-generations profile)) + number + #f)))))) + + (define* (relative-generation profile shift #:optional (current (generation-number profile))) "Return PROFILE's generation shifted from the CURRENT generation by SHIFT. -- cgit v1.2.3