From 6a7f8cfd7373afe664b3f0412c02d7b1beeb5c7a Mon Sep 17 00:00:00 2001
From: Mark H Weaver <mhw@netris.org>
Date: Tue, 12 Feb 2013 01:24:21 -0500
Subject: [PATCH 2/2] Implement guix-package --upgrade.

* guix-package.in (%options): Add --upgrade/-u option.
  (newest-available-packages, upgradeable?): New procedures.
  (process-actions): Implement upgrade option.
---
 guix-package.in |   78 +++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 67 insertions(+), 11 deletions(-)

diff --git a/guix-package.in b/guix-package.in
index 32d9afd..f00b7e7 100644
--- a/guix-package.in
+++ b/guix-package.in
@@ -52,6 +52,7 @@ exec "${GUILE-@GUILE@}" -c "$startup" "@guilemoduledir@" "$0" "$@"
   #:use-module (ice-9 format)
   #:use-module (ice-9 match)
   #:use-module (ice-9 regex)
+  #:use-module (ice-9 vlist)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-26)
@@ -356,6 +357,9 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
         (option '(#\r "remove") #t #f
                 (lambda (opt name arg result)
                   (alist-cons 'remove arg result)))
+        (option '(#\u "upgrade") #t #f
+                (lambda (opt name arg result)
+                  (alist-cons 'upgrade arg result)))
         (option '("roll-back") #f #f
                 (lambda (opt name arg result)
                   (alist-cons 'roll-back? #t result)))
@@ -468,6 +472,41 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
         (()
          (leave (_ "~a: package not found~%") request)))))
 
+  (define (newest-available-packages)
+    ;; Return a vhash with elements of the form:
+    ;; (name newest-version newest-package ...)
+    ;; where the preferred package is listed first.
+
+    ;; FIXME: Currently, the preferred package is whichever one
+    ;; was found last by 'fold-packages'.  Find a better solution.
+    (fold-packages (lambda (p r)
+                     (let ((name    (package-name p))
+                           (version (package-version p)))
+                       (match (vhash-assoc name r)
+                         ((_ newest-so-far . pkgs)
+                          (case (version-compare version newest-so-far)
+                            ((>) (vhash-cons name `(,version ,p) r))
+                            ((=) (vhash-cons name `(,version ,p ,@pkgs) r))
+                            ((<) r)))
+                         (#f (vhash-cons name `(,version ,p) r)))))
+                   vlist-null))
+
+  (define (upgradeable? name current-version current-path newest)
+    ;; Return #t if there is a newer version available, or if the
+    ;; newest version if the same as the current one but the
+    ;; output path would be different than the current path.
+
+    ;; NEWEST must be the result of (newest-available-packages).
+    (match (vhash-assoc name newest)
+      ((_ candidate-version pkg . rest)
+       (case (version-compare candidate-version current-version)
+         ((>) #t)
+         ((<) #f)
+         ((=) (let* ((candidate-path (derivation-path->output-path
+                                      (package-derivation (%store) pkg))))
+                (not (string=? current-path candidate-path))))))
+      (#f #f)))
+
   (define (ensure-default-profile)
     ;; Ensure the default profile symlink and directory exist.
 
@@ -520,13 +559,33 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
         (begin
           (roll-back profile)
           (process-actions (alist-delete 'roll-back? opts)))
-        (let* ((install  (filter-map (match-lambda
-                                      (('install . (? store-path?))
-                                       #f)
-                                      (('install . package)
-                                       (find-package package))
-                                      (_ #f))
-                                     opts))
+        (let* ((installed (manifest-packages (profile-manifest profile)))
+               (upgrade-regexps (filter-map (match-lambda
+                                             (('upgrade . regexp)
+                                              (make-regexp regexp))
+                                             (_ #f))
+                                            opts))
+               (upgrade  (if (null? upgrade-regexps)
+                             '()
+                             (let ((newest (newest-available-packages)))
+                               (filter-map (match-lambda
+                                            ((name version output path _)
+                                             (and (any (cut regexp-exec <> name)
+                                                       upgrade-regexps)
+                                                  (upgradeable? name version path
+                                                                newest)
+                                                  (find-package name)))
+                                            (_ #f))
+                                           installed))))
+               (install  (append
+                          upgrade
+                          (filter-map (match-lambda
+                                       (('install . (? store-path?))
+                                        #f)
+                                       (('install . package)
+                                        (find-package package))
+                                       (_ #f))
+                                      opts)))
                (drv      (filter-map (match-lambda
                                       ((name version sub-drv
                                              (? package? package)
@@ -563,10 +622,7 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
                                          (match package
                                            ((name _ ...)
                                             (alist-delete name result))))
-                                       (fold alist-delete
-                                             (manifest-packages
-                                              (profile-manifest profile))
-                                             remove)
+                                       (fold alist-delete installed remove)
                                        install*))))
 
           (when (equal? profile %current-profile)
-- 
1.7.10.4