emacs: Add "Source" field to 'guix-info' buffers.

Suggested by Ludovic Courtès.

* emacs/guix-info.el (guix-info-insert-methods, guix-info-displayed-params):
  Add 'source' parameter.
  (guix-package-info-source): New face.
  (guix-package-source): New button type.
  (guix-package-info-auto-find-source, guix-package-info-auto-download-source,
  guix-package-info-download-buffer): New variables.
  (guix-package-info-show-source, guix-package-info-insert-source-url,
  guix-package-info-insert-source, guix-package-info-download-source,
  guix-package-info-redisplay-after-download): New procedures.
* emacs/guix-base.el (guix-param-titles): Add 'source' parameter.
  (guix-operation-prompt): Add 'prompt' argument.
  (guix-after-source-download-hook): New variable.
  (guix-package-source-path, guix-package-source-build-derivation): New
  procedures.
* emacs/guix-main.scm (%package-param-alist): Add 'source' parameter.
  (package-source-names, package-source-derivation->store-path,
  package-source-path, package-source-build-derivation): New procedures.

emacs/guix-base.el

@@ -82,6 +82,7 @@ Interactively, prompt for PATH.  With prefix, use
      (id                . "ID")
      (name              . "Name")
      (version           . "Version")
+     (source            . "Source")
      (license           . "License")
      (synopsis          . "Synopsis")
      (description       . "Description")
@@ -100,6 +101,7 @@ Interactively, prompt for PATH.  With prefix, use
      (id                . "ID")
      (name              . "Name")
      (version           . "Version")
+     (source            . "Source")
      (license           . "License")
      (synopsis          . "Synopsis")
      (description       . "Description")
@@ -954,13 +956,14 @@ ENTRIES is a list of package entries to get info about packages."
           strings)
     (insert "\n")))
 
-(defun guix-operation-prompt ()
+(defun guix-operation-prompt (&optional prompt)
   "Prompt a user for continuing the current operation.
-Return non-nil, if the operation should be continued; nil otherwise."
+Return non-nil, if the operation should be continued; nil otherwise.
+Ask a user with PROMPT for continuing an operation."
   (let* ((option-keys (mapcar #'guix-operation-option-key
                               guix-operation-options))
          (keys (append '(?y ?n) option-keys))
-         (prompt (concat (propertize "Continue operation?"
+         (prompt (concat (propertize (or prompt "Continue operation?")
                                      'face 'minibuffer-prompt)
                          " ("
                          (mapconcat
@@ -1035,6 +1038,30 @@ Each element from GENERATIONS is a generation number."
       'switch-to-generation profile generation)
      operation-buffer)))
 
+(defun guix-package-source-path (package-id)
+  "Return a store file path to a source of a package PACKAGE-ID."
+  (message "Calculating the source derivation ...")
+  (guix-eval-read
+   (guix-make-guile-expression
+    'package-source-path package-id)))
+
+(defvar guix-after-source-download-hook nil
+  "Hook run after successful performing a 'source-download' operation.")
+
+(defun guix-package-source-build-derivation (package-id &optional prompt)
+  "Build source derivation of a package PACKAGE-ID.
+Ask a user with PROMPT for continuing an operation."
+  (when (or (not guix-operation-confirm)
+            (guix-operation-prompt (or prompt
+                                       "Build the source derivation?")))
+    (guix-eval-in-repl
+     (guix-make-guile-expression
+      'package-source-build-derivation
+      package-id
+      :use-substitutes? (or guix-use-substitutes 'f)
+      :dry-run? (or guix-dry-run 'f))
+     nil 'source-download)))
+
 
 ;;; Pull
 

emacs/guix-info.el

@@ -1,4 +1,4 @@
-;;; guix-info.el --- Info buffers for displaying entries
+;;; guix-info.el --- Info buffers for displaying entries   -*- lexical-binding: t -*-
 
 ;; Copyright © 2014 Alex Kost <alezost@gmail.com>
 
@@ -24,7 +24,6 @@
 
 ;;; Code:
 
-(require 'guix-history)
 (require 'guix-base)
 (require 'guix-utils)
 
@@ -107,6 +106,8 @@ number of characters, it will be split into several lines.")
                         guix-info-insert-title-simple)
      (outputs           guix-package-info-insert-outputs
                         guix-info-insert-title-simple)
+     (source            guix-package-info-insert-source
+                        guix-info-insert-title-simple)
      (home-url          guix-info-insert-url)
      (inputs            guix-package-info-insert-inputs)
      (native-inputs     guix-package-info-insert-native-inputs)
@@ -121,6 +122,8 @@ number of characters, it will be split into several lines.")
      (name              guix-package-info-name)
      (version           guix-output-info-insert-version)
      (output            guix-output-info-insert-output)
+     (source            guix-package-info-insert-source
+                        guix-info-insert-title-simple)
      (path              guix-package-info-insert-output-path
                         guix-info-insert-title-simple)
      (dependencies      guix-package-info-insert-output-dependencies
@@ -157,10 +160,11 @@ is a function, this function is called with parameter title as
 argument.")
 
 (defvar guix-info-displayed-params
-  '((package name version synopsis outputs location home-url
+  '((package name version synopsis outputs source location home-url
              license inputs native-inputs propagated-inputs description)
-    (output name version output synopsis path dependencies location home-url
+    (output name version output synopsis source path dependencies location
-            license inputs native-inputs propagated-inputs description)
+            home-url license inputs native-inputs propagated-inputs
+            description)
     (installed path dependencies)
     (generation number prev-number current time path))
   "List of displayed entry parameters.
@@ -651,6 +655,122 @@ ENTRY is an alist with package info."
 (defalias 'guix-package-info-insert-output-dependencies
   'guix-package-info-insert-output-path)
 
+
+;;; Inserting a source
+
+(defface guix-package-info-source
+  '((t :inherit link :underline nil))
+  "Face used for a source URL of a package."
+  :group 'guix-package-info)
+
+(defcustom guix-package-info-auto-find-source nil
+  "If non-nil, find a source file after pressing a \"Show\" button.
+If nil, just display the source file path without finding."
+  :type 'boolean
+  :group 'guix-package-info)
+
+(defcustom guix-package-info-auto-download-source t
+  "If nil, do not automatically download a source file if it doesn't exist.
+After pressing a \"Show\" button, a derivation of the package
+source is calculated and a store file path is displayed.  If this
+variable is non-nil and the source file does not exist in the
+store, it will be automatically downloaded (with a possible
+prompt depending on `guix-operation-confirm' variable)."
+  :type 'boolean
+  :group 'guix-package-info)
+
+(defvar guix-package-info-download-buffer nil
+  "Buffer from which a current download operation was performed.")
+
+(define-button-type 'guix-package-source
+  :supertype 'guix
+  'face 'guix-package-info-source
+  'help-echo ""
+  'action (lambda (_)
+            ;; As a source may not be a real URL (e.g., "mirror://..."),
+            ;; no action is bound to a source button.
+            (message "Yes, this is the source URL. What did you expect?")))
+
+(defun guix-package-info-insert-source-url (url &optional _)
+  "Make button from source URL and insert it at point."
+  (guix-insert-button url 'guix-package-source))
+
+(defun guix-package-info-show-source (entry-id package-id)
+  "Show file name of a package source in the current info buffer.
+Find the file if needed (see `guix-package-info-auto-find-source').
+ENTRY-ID is an ID of the current entry (package or output).
+PACKAGE-ID is an ID of the package which source to show."
+  (let* ((entry (guix-get-entry-by-id entry-id guix-entries))
+         (file  (guix-package-source-path package-id)))
+    (or file
+        (error "Couldn't define file path of the package source"))
+    (let* ((new-entry (cons (cons 'source-file file)
+                            entry))
+           (entries (cl-substitute-if
+                     new-entry
+                     (lambda (entry)
+                       (equal (guix-get-key-val entry 'id)
+                              entry-id))
+                     guix-entries
+                     :count 1)))
+      (guix-redisplay-buffer :entries entries)
+      (if (file-exists-p file)
+          (if guix-package-info-auto-find-source
+              (guix-find-file file)
+            (message "The source store path is displayed."))
+        (if guix-package-info-auto-download-source
+            (guix-package-info-download-source package-id)
+          (message "The source does not exist in the store."))))))
+
+(defun guix-package-info-download-source (package-id)
+  "Download a source of the package PACKAGE-ID."
+  (setq guix-package-info-download-buffer (current-buffer))
+  (guix-package-source-build-derivation
+   package-id
+   "The source does not exist in the store. Download it?"))
+
+(defun guix-package-info-insert-source (source entry)
+  "Insert SOURCE from package ENTRY at point.
+SOURCE is a list of URLs."
+  (guix-info-insert-indent)
+  (if (null source)
+      (guix-format-insert nil)
+    (let* ((source-file (guix-get-key-val entry 'source-file))
+           (entry-id    (guix-get-key-val entry 'id))
+           (package-id  (or (guix-get-key-val entry 'package-id)
+                            entry-id)))
+      (if (null source-file)
+          (guix-info-insert-action-button
+           "Show"
+           (lambda (btn)
+             (guix-package-info-show-source (button-get btn 'entry-id)
+                                            (button-get btn 'package-id)))
+           "Show the source store path of the current package"
+           'entry-id entry-id
+           'package-id package-id)
+        (unless (file-exists-p source-file)
+          (guix-info-insert-action-button
+           "Download"
+           (lambda (btn)
+             (guix-package-info-download-source
+              (button-get btn 'package-id)))
+           "Download the source into the store"
+           'package-id package-id))
+        (guix-info-insert-val-simple source-file
+                                     #'guix-info-insert-file-path))
+      (guix-info-insert-val-simple source
+                                   #'guix-package-info-insert-source-url))))
+
+(defun guix-package-info-redisplay-after-download ()
+  "Redisplay an 'info' buffer after downloading the package source.
+This function is used to hide a \"Download\" button if needed."
+  (when (buffer-live-p guix-package-info-download-buffer)
+    (guix-redisplay-buffer :buffer guix-package-info-download-buffer)
+    (setq guix-package-info-download-buffer nil)))
+
+(add-hook 'guix-after-source-download-hook
+          'guix-package-info-redisplay-after-download)
+
 
 ;;; Displaying outputs
 

emacs/guix-main.scm

@@ -46,10 +46,12 @@
  (ice-9 vlist)
  (ice-9 match)
  (srfi srfi-1)
+ (srfi srfi-2)
  (srfi srfi-11)
  (srfi srfi-19)
  (srfi srfi-26)
  (guix)
+ (guix git-download)
  (guix packages)
  (guix profiles)
  (guix licenses)
@@ -252,6 +254,18 @@ Example:
                      (license-name license)))
               (list-maybe (package-license package))))
 
+(define (package-source-names package)
+  "Return a list of source names (URLs) of the PACKAGE."
+  (let ((source (package-source package)))
+    (and (origin? source)
+         (filter-map (lambda (uri)
+                       (cond ((string? uri)
+                              uri)
+                             ((git-reference? uri)
+                              (git-reference-url uri))
+                             (else "Unknown source type")))
+                     (list-maybe (origin-uri source))))))
+
 (define (package-unique? package)
   "Return #t if PACKAGE is a single package with such name/version."
   (null? (cdr (packages-by-name (package-name package)
@@ -263,6 +277,7 @@ Example:
     (name              . ,package-name)
     (version           . ,package-version)
     (license           . ,package-license-names)
+    (source            . ,package-source-names)
     (synopsis          . ,package-synopsis)
     (description       . ,package-description)
     (home-url          . ,package-home-page)
@@ -867,3 +882,37 @@ OUTPUTS is a list of package outputs (may be an empty list)."
 GENERATIONS is a list of generation numbers."
   (with-store store
     (delete-generations store profile generations)))
+
+(define (package-source-derivation->store-path derivation)
+  "Return a store path of the package source DERIVATION."
+  (match (derivation-outputs derivation)
+    ;; Source derivation is always (("out" . derivation)).
+    (((_ . output-drv))
+     (derivation-output-path output-drv))
+    (_ #f)))
+
+(define (package-source-path package-id)
+  "Return a store file path to a source of a package PACKAGE-ID."
+  (and-let* ((package (package-by-id package-id))
+             (source  (package-source package)))
+    (with-store store
+      (package-source-derivation->store-path
+       (package-source-derivation store source)))))
+
+(define* (package-source-build-derivation package-id #:key dry-run?
+                                          (use-substitutes? #t))
+  "Build source derivation of a package PACKAGE-ID."
+  (and-let* ((package (package-by-id package-id))
+             (source  (package-source package)))
+    (with-store store
+      (let* ((derivation  (package-source-derivation store source))
+             (derivations (list derivation)))
+        (set-build-options store
+                           #:use-substitutes? use-substitutes?)
+        (show-what-to-build store derivations
+                            #:use-substitutes? use-substitutes?
+                            #:dry-run? dry-run?)
+        (unless dry-run?
+          (build-derivations store derivations))
+        (format #t "The source store path: ~a~%"
+                (package-source-derivation->store-path derivation))))))