emacs: Add minibuffer readers.

* emacs/guix-read.el: New file.
* emacs.am (ELFILES): Add it.

emacs.am

@@ -29,6 +29,7 @@ ELFILES =					\
   emacs/guix-messages.el			\
   emacs/guix-pcomplete.el			\
   emacs/guix-prettify.el			\
+  emacs/guix-read.el				\
   emacs/guix-utils.el				\
   emacs/guix.el
 

emacs/guix-read.el

+;;; guix-read.el --- Minibuffer readers
+
+;; Copyright © 2015 Alex Kost <alezost@gmail.com>
+
+;; This file is part of GNU Guix.
+
+;; GNU Guix is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Guix is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This file provides functions to prompt a user for packages, system
+;; types, hash formats and other guix related stuff.
+
+;;; Code:
+
+(require 'guix-help-vars)
+(require 'guix-utils)
+(require 'guix-base)
+
+(defun guix-read-file-name (prompt &optional dir default-filename
+                                   mustmatch initial predicate)
+  "Read file name.
+This function is similar to `read-file-name' except it also
+expands the file name."
+  (expand-file-name (read-file-name prompt dir default-filename
+                                    mustmatch initial predicate)))
+
+(defmacro guix-define-reader (name read-fun completions prompt)
+  "Define NAME function to read from minibuffer.
+READ-FUN may be `completing-read', `completing-read-multiple' or
+another function with the same arguments."
+  `(defun ,name (&optional prompt initial-contents)
+     (,read-fun ,(if prompt
+                     `(or prompt ,prompt)
+                   'prompt)
+                ,completions nil nil initial-contents)))
+
+(defmacro guix-define-readers (&rest args)
+  "Define reader functions.
+
+ARGS should have a form [KEYWORD VALUE] ...  The following
+keywords are available:
+
+  - `completions-var' - variable used to get completions.
+
+  - `completions-getter' - function used to get completions.
+
+  - `single-reader', `single-prompt' - name of a function to read
+    a single value, and a prompt for it.
+
+  - `multiple-reader', `multiple-prompt' - name of a function to
+    read multiple values, and a prompt for it.
+
+  - `multiple-separator' - if specified, another
+    `<multiple-reader-name>-string' function returning a string
+    of multiple values separated the specified separator will be
+    defined."
+  (let (completions-var
+        completions-getter
+        single-reader
+        single-prompt
+        multiple-reader
+        multiple-prompt
+        multiple-separator)
+
+    ;; Process the keyword args.
+    (while (keywordp (car args))
+      (pcase (pop args)
+        (`:completions-var    (setq completions-var    (pop args)))
+        (`:completions-getter (setq completions-getter (pop args)))
+        (`:single-reader      (setq single-reader      (pop args)))
+        (`:single-prompt      (setq single-prompt      (pop args)))
+        (`:multiple-reader    (setq multiple-reader    (pop args)))
+        (`:multiple-prompt    (setq multiple-prompt    (pop args)))
+        (`:multiple-separator (setq multiple-separator (pop args)))
+	(_ (pop args))))
+
+    (let ((completions
+           (cond ((and completions-var completions-getter)
+                  `(or ,completions-var
+                       (setq ,completions-var
+                             (funcall ',completions-getter))))
+                 (completions-var
+                  completions-var)
+                 (completions-getter
+                  `(funcall ',completions-getter)))))
+      `(progn
+         ,(when (and completions-var
+                     (not (boundp completions-var)))
+            `(defvar ,completions-var nil))
+
+         ,(when single-reader
+            `(guix-define-reader ,single-reader completing-read
+                                 ,completions ,single-prompt))
+
+         ,(when multiple-reader
+            `(guix-define-reader ,multiple-reader completing-read-multiple
+                                 ,completions ,multiple-prompt))
+
+         ,(when (and multiple-reader multiple-separator)
+            (let ((name (intern (concat (symbol-name multiple-reader)
+                                        "-string"))))
+              `(defun ,name (&optional prompt initial-contents)
+                 (guix-concat-strings
+                  (,multiple-reader prompt initial-contents)
+                  ,multiple-separator))))))))
+
+(guix-define-readers
+ :completions-var guix-help-system-types
+ :single-reader guix-read-system-type
+ :single-prompt "System type: ")
+
+(guix-define-readers
+ :completions-var guix-help-source-types
+ :single-reader guix-read-source-type
+ :single-prompt "Source type: ")
+
+(guix-define-readers
+ :completions-var guix-help-hash-formats
+ :single-reader guix-read-hash-format
+ :single-prompt "Hash format: ")
+
+(guix-define-readers
+ :completions-var guix-help-refresh-subsets
+ :single-reader guix-read-refresh-subset
+ :single-prompt "Refresh subset: ")
+
+(guix-define-readers
+ :completions-var guix-help-key-policies
+ :single-reader guix-read-key-policy
+ :single-prompt "Key policy: ")
+
+(guix-define-readers
+ :completions-var guix-help-elpa-archives
+ :single-reader guix-read-elpa-archive
+ :single-prompt "ELPA archive: ")
+
+(guix-define-readers
+ :completions-var guix-help-verify-options
+ :multiple-reader guix-read-verify-options
+ :multiple-prompt "Verify option,s: "
+ :multiple-separator ",")
+
+(guix-define-readers
+ :completions-getter guix-graph-type-names
+ :single-reader guix-read-graph-type
+ :single-prompt "Graph node type: ")
+
+(guix-define-readers
+ :completions-getter guix-lint-checker-names
+ :multiple-reader guix-read-lint-checker-names
+ :multiple-prompt "Linter,s: "
+ :multiple-separator ",")
+
+(guix-define-readers
+ :completions-getter guix-package-names
+ :single-reader guix-read-package-name
+ :single-prompt "Package: "
+ :multiple-reader guix-read-package-names
+ :multiple-prompt "Package,s: "
+ :multiple-separator " ")
+
+(provide 'guix-read)
+
+;;; guix-read.el ends here