build: Add 'emacs-build-system'.

* Makefile.am (MODULES): Add 'guix/build-system/emacs.scm' and
  'guix/build/emacs-build-system.scm'.
* guix/build-system/emacs.scm: New file.
* guix/build/emacs-build-system.scm: New file.
* doc/guix.texi (Build Systems): Document it.

1 files changed, 200 insertions, 0 deletions

diff --git a/guix/build/emacs-build-system.scm b/guix/build/emacs-build-system.scm
new file mode 100644
index 0000000000..dd3cfc47ac
--- /dev/null
+++ b/guix/build/emacs-build-system.scm
@@ -0,0 +1,200 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2015 Federico Beffa <beffa@fbengineering.ch>
+;;;
+;;; 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 GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix build emacs-build-system)
+  #:use-module ((guix build gnu-build-system) #:prefix gnu:)
+  #:use-module (guix build utils)
+  #:use-module (guix build emacs-utils)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:use-module (ice-9 rdelim)
+  #:use-module (ice-9 regex)
+  #:use-module (ice-9 match)
+  #:export (%standard-phases
+            emacs-build))
+
+;; Commentary:
+;;
+;; Builder-side code of the build procedure for ELPA Emacs packages.
+;;
+;; Code:
+
+;; Directory suffix where we install ELPA packages.  We avoid ".../elpa" as
+;; Emacs expects to find the ELPA repository 'archive-contents' file and the
+;; archive signature.
+(define %install-suffix "/share/emacs/site-lisp/guix.d")
+
+(define* (build #:key outputs inputs #:allow-other-keys)
+  "Compile .el files."
+  (let* ((emacs (string-append (assoc-ref inputs "emacs") "/bin/emacs"))
+         (out (assoc-ref outputs "out"))
+         (elpa-name-ver (store-directory->elpa-name-version out))
+         (el-dir (string-append out %install-suffix "/" elpa-name-ver))
+         (deps-dirs (emacs-inputs-directories inputs)))
+    (setenv "SHELL" "sh")
+    (parameterize ((%emacs emacs))
+      (emacs-byte-compile-directory el-dir
+                                    (emacs-inputs-el-directories deps-dirs)))))
+
+(define* (patch-el-files #:key outputs #:allow-other-keys)
+  "Substitute the absolute \"/bin/\" directory with the right location in the
+store in '.el' files."
+  (let* ((out (assoc-ref outputs "out"))
+         (elpa-name-ver (store-directory->elpa-name-version out))
+         (el-dir (string-append out %install-suffix "/" elpa-name-ver))
+         (substitute-cmd (lambda ()
+                           (substitute* (find-files "." "\\.el$")
+                             (("\"/bin/(.*)\"" _ cmd)
+                              (string-append "\"" (which cmd) "\""))))))
+    (with-directory-excursion el-dir
+      ;; Some old '.el' files (e.g., tex-buf.el in AUCTeX) are still encoded
+      ;; with the "ISO-8859-1" locale.
+      (unless (false-if-exception (substitute-cmd))
+        (with-fluids ((%default-port-encoding "ISO-8859-1"))
+          (substitute-cmd))))
+    #t))
+
+(define* (install #:key outputs #:allow-other-keys)
+  "Install the package contents."
+  (let* ((out (assoc-ref outputs "out"))
+         (elpa-name-ver (store-directory->elpa-name-version out))
+         (src-dir (getcwd))
+         (tgt-dir (string-append out %install-suffix "/" elpa-name-ver)))
+    (copy-recursively src-dir tgt-dir)
+    #t))
+
+(define* (move-doc #:key outputs #:allow-other-keys)
+  "Move info files from the ELPA package directory to the info directory."
+  (let* ((out (assoc-ref outputs "out"))
+         (elpa-name-ver (store-directory->elpa-name-version out))
+         (el-dir (string-append out %install-suffix "/" elpa-name-ver))
+         (name-ver (store-directory->name-version out))
+         (info-dir (string-append out "/share/info/" name-ver))
+         (info-files (find-files el-dir "\\.info$")))
+    (unless (null? info-files)
+      (mkdir-p info-dir)
+      (with-directory-excursion el-dir
+        (when (file-exists? "dir") (delete-file "dir"))
+        (for-each (lambda (f)
+                    (copy-file f (string-append info-dir "/" (basename f)))
+                    (delete-file f))
+                  info-files)))
+    #t))
+
+(define* (make-autoloads #:key outputs inputs #:allow-other-keys)
+  "Generate the autoloads file."
+  (let* ((emacs (string-append (assoc-ref inputs "emacs") "/bin/emacs"))
+         (out (assoc-ref outputs "out"))
+         (elpa-name-ver (store-directory->elpa-name-version out))
+         (elpa-name (package-name->name+version elpa-name-ver))
+         (el-dir (string-append out %install-suffix "/" elpa-name-ver)))
+    (parameterize ((%emacs emacs))
+      (emacs-generate-autoloads elpa-name el-dir))
+    #t))
+
+(define (emacs-package? name)
+  "Check if NAME correspond to the name of an Emacs package."
+  (string-prefix? "emacs-" name))
+
+(define (emacs-inputs inputs)
+  "Retrieve the list of Emacs packages from INPUTS."
+  (filter (match-lambda
+            ((label directory)
+             (emacs-package? ((compose package-name->name+version
+                                       store-directory->name-version)
+                              directory)))
+            (_ #f))
+          inputs))
+
+(define (emacs-inputs-directories inputs)
+  "Extract the list of Emacs package directories from INPUTS."
+  (let ((inputs (emacs-inputs inputs)))
+    (match inputs
+      (((names . directories) ...) directories))))
+
+(define (emacs-inputs-el-directories dirs)
+  "Build the list of Emacs Lisp directories from the Emacs package directory
+DIRS."
+  (map (lambda (d)
+         (string-append d %install-suffix "/"
+                        (store-directory->elpa-name-version d)))
+       dirs))
+
+(define (package-name-version->elpa-name-version name-ver)
+  "Convert the Guix package NAME-VER to the corresponding ELPA name-version
+format.  Essnetially drop the prefix used in Guix."
+  (let ((name (store-directory->name-version name-ver)))
+    (if (emacs-package? name-ver)
+        (store-directory->name-version name-ver)
+        name-ver)))
+
+(define (store-directory->elpa-name-version store-dir)
+  "Given a store directory STORE-DIR return the part of the basename after the
+second hyphen.  This corresponds to 'name-version' as used in ELPA packages."
+  ((compose package-name-version->elpa-name-version
+            store-directory->name-version)
+   store-dir))
+
+(define (store-directory->name-version store-dir)
+  "Given a store directory STORE-DIR return the part of the basename
+after the first hyphen.  This corresponds to 'name-version' of the package."
+  (let* ((base (basename store-dir)))
+    (string-drop base
+                 (+ 1 (string-index base #\-)))))
+
+;; from (guix utils).  Should we put it in (guix build utils)?
+(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
+#f are returned.  The first hyphen followed by a digit is considered to
+introduce the version part."
+  ;; See also `DrvName' in Nix.
+
+  (define number?
+    (cut char-set-contains? char-set:digit <>))
+
+  (let loop ((chars   (string->list name))
+             (prefix '()))
+    (match chars
+      (()
+       (values name #f))
+      ((#\- (? number? n) rest ...)
+       (values (list->string (reverse prefix))
+               (list->string (cons n rest))))
+      ((head tail ...)
+       (loop tail (cons head prefix))))))
+
+(define %standard-phases
+  (modify-phases gnu:%standard-phases
+    (delete 'configure)
+    (delete 'check)
+    (delete 'install)
+    (replace 'build build)
+    (add-before 'build 'install install)
+    (add-after 'install 'make-autoloads make-autoloads)
+    (add-after 'make-autoloads 'patch-el-files patch-el-files)
+    (add-after 'make-autoloads 'move-doc move-doc)))
+
+(define* (emacs-build #:key inputs (phases %standard-phases)
+                      #:allow-other-keys #:rest args)
+  "Build the given Emacs package, applying all of PHASES in order."
+  (apply gnu:gnu-build
+         #:inputs inputs #:phases phases
+         args))
+
+;;; emacs-build-system.scm ends here