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;;; guix-backend.el --- Communication with Geiser
;; Copyright © 2014 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 the code for interacting with Guile using Geiser.
;; By default (if `guix-use-guile-server' is non-nil) 2 Geiser REPLs are
;; started. The main one (with "guile --listen" process) is used for
;; "interacting" with a user - for showing a progress of
;; installing/deleting Guix packages. The second (internal) REPL is
;; used for synchronous evaluating, e.g. when information about
;; packages/generations should be received for a list/info buffer.
;;
;; This "2 REPLs concept" makes it possible to have a running process of
;; installing/deleting packages and to continue to search/list/get info
;; about other packages at the same time. If you prefer to use a single
;; Guix REPL, do not try to receive any information while there is a
;; running code in the REPL (see
;; <https://github.com/jaor/geiser/issues/28>).
;;
;; If you need to use "guix.el" in another Emacs (i.e. when there is
;; a runnig "guile --listen..." REPL somewhere), you can either change
;; `guix-default-port' in that Emacs instance or set
;; `guix-use-guile-server' to t.
;;
;; Guix REPLs (unlike the usual Geiser REPLs) are not added to
;; `geiser-repl--repls' variable, and thus cannot be used for evaluating
;; while editing scm-files. The only purpose of Guix REPLs is to be an
;; intermediate between "Guix/Guile level" and "Emacs interface level".
;; That being said you can still want to use a Guix REPL while hacking
;; auxiliary scheme-files for "guix.el". You can just use "M-x
;; connect-to-guile" (connect to "localhost" and `guix-default-port') to
;; have a usual Geiser REPL with all stuff defined by "guix.el" package.
;;; Code:
(require 'geiser-mode)
(require 'guix-emacs)
(defvar guix-load-path
(file-name-directory (or load-file-name
(locate-library "guix")))
"Directory with scheme files for \"guix.el\" package.")
(defvar guix-helper-file
(expand-file-name "guix-helper.scm" guix-load-path)
"Auxiliary scheme file for loading.")
(defvar guix-guile-program (or geiser-guile-binary "guile")
"Name of the guile executable used for Guix REPL.
May be either a string (the name of the executable) or a list of
strings of the form:
(NAME . ARGS)
Where ARGS is a list of arguments to the guile program.")
;;; REPL
(defgroup guix-repl nil
"Settings for Guix REPLs."
:prefix "guix-repl-"
:group 'guix)
(defcustom guix-repl-startup-time 30000
"Time, in milliseconds, to wait for Guix REPL to startup.
Same as `geiser-repl-startup-time' but is used for Guix REPL.
If you have a slow system, try to increase this time."
:type 'integer
:group 'guix-repl)
(defcustom guix-repl-buffer-name "*Guix REPL*"
"Default name of a Geiser REPL buffer used for Guix."
:type 'string
:group 'guix-repl)
(defcustom guix-after-start-repl-hook ()
"Hook called after Guix REPL is started."
:type 'hook
:group 'guix-repl)
(defcustom guix-use-guile-server t
"If non-nil, start guile with '--listen' argument.
This allows to receive information about packages using an additional
REPL while some packages are being installed/removed in the main REPL."
:type 'boolean
:group 'guix-repl)
(defcustom guix-default-port 37246
"Default port used if `guix-use-guile-server' is non-nil."
:type 'integer
:group 'guix-repl)
(defvar guix-repl-buffer nil
"Main Geiser REPL buffer used for communicating with Guix.
This REPL is used for processing package actions and for
receiving information if `guix-use-guile-server' is nil.")
(defvar guix-internal-repl-buffer nil
"Additional Geiser REPL buffer used for communicating with Guix.
This REPL is used for receiving information only if
`guix-use-guile-server' is non-nil.")
(defvar guix-internal-repl-buffer-name "*Guix Internal REPL*"
"Default name of an internal Guix REPL buffer.")
(defvar guix-before-repl-operation-hook nil
"Hook run before executing an operation in Guix REPL.")
(defvar guix-after-repl-operation-hook
'(guix-emacs-load-autoloads-maybe
guix-repl-operation-success-message)
"Hook run after executing successful operation in Guix REPL.")
(defvar guix-repl-operation-p nil
"Non-nil, if current operation is performed by `guix-eval-in-repl'.
This internal variable is used to distinguish Guix operations
from operations performed in Guix REPL by a user.")
(defvar guix-repl-operation-type nil
"Type of the current operation performed by `guix-eval-in-repl'.
This internal variable is used to define what actions should be
executed after the current operation succeeds.
See `guix-eval-in-repl' for details.")
(defun guix-repl-operation-success-message ()
"Message telling about successful Guix operation."
(message "Guix operation has been performed."))
(defun guix-get-guile-program (&optional internal)
"Return a value suitable for `geiser-guile-binary'."
(if (or internal
(not guix-use-guile-server))
guix-guile-program
(append (if (listp guix-guile-program)
guix-guile-program
(list guix-guile-program))
;; Guile understands "--listen=..." but not "--listen ..."
(list (concat "--listen="
(number-to-string guix-default-port))))))
(defun guix-start-process-maybe (&optional start-msg end-msg)
"Start Geiser REPL configured for Guix if needed.
START-MSG and END-MSG are strings displayed in the minibuffer in
the beginning and in the end of the starting process. If nil,
display default messages."
(guix-start-repl-maybe nil
(or start-msg "Starting Guix REPL ...")
(or end-msg "Guix REPL has been started."))
(if guix-use-guile-server
(guix-start-repl-maybe 'internal)
(setq guix-internal-repl-buffer guix-repl-buffer)))
(defun guix-start-repl-maybe (&optional internal start-msg end-msg)
"Start Guix REPL if needed.
If INTERNAL is non-nil, start an internal REPL.
START-MSG and END-MSG are strings displayed in the minibuffer in
the beginning and in the end of the process. If nil, do not
display messages."
(let* ((repl-var (guix-get-repl-buffer-variable internal))
(repl (symbol-value repl-var)))
(unless (and (buffer-live-p repl)
(get-buffer-process repl))
(and start-msg (message start-msg))
(setq guix-repl-operation-p nil)
(let ((geiser-guile-binary (guix-get-guile-program internal))
(geiser-guile-init-file (or internal guix-helper-file))
(repl (get-buffer-create
(guix-get-repl-buffer-name internal))))
(condition-case err
(guix-start-repl repl
(and internal
(geiser-repl--read-address
"localhost" guix-default-port)))
(text-read-only
(error (concat "Couldn't start Guix REPL. Perhaps the port %s is busy.\n"
"See buffer '%s' for details")
guix-default-port (buffer-name repl))))
(set repl-var repl)
(and end-msg (message end-msg))
(unless internal
(run-hooks 'guix-after-start-repl-hook))))))
(defun guix-start-repl (buffer &optional address)
"Start Guix REPL in BUFFER.
If ADDRESS is non-nil, connect to a remote guile process using
this address (it should be defined by
`geiser-repl--read-address')."
;; A mix of the code from `geiser-repl--start-repl' and
;; `geiser-repl--to-repl-buffer'.
(let ((impl 'guile)
(geiser-guile-load-path (cons guix-load-path
geiser-guile-load-path))
(geiser-repl-startup-time guix-repl-startup-time))
(with-current-buffer buffer
(geiser-repl-mode)
(geiser-impl--set-buffer-implementation impl)
(geiser-repl--autodoc-mode -1)
(goto-char (point-max))
(let ((prompt (geiser-con--combined-prompt
geiser-guile--prompt-regexp
geiser-guile--debugger-prompt-regexp)))
(geiser-repl--save-remote-data address)
(geiser-repl--start-scheme impl address prompt)
(geiser-repl--quit-setup)
(geiser-repl--history-setup)
(setq-local geiser-repl--repls (list buffer))
(geiser-repl--set-this-buffer-repl buffer)
(setq geiser-repl--connection
(geiser-con--make-connection
(get-buffer-process (current-buffer))
geiser-guile--prompt-regexp
geiser-guile--debugger-prompt-regexp))
(geiser-repl--startup impl address)
(geiser-repl--autodoc-mode 1)
(geiser-company--setup geiser-repl-company-p)
(add-hook 'comint-output-filter-functions
'guix-repl-output-filter
nil t)
(set-process-query-on-exit-flag
(get-buffer-process (current-buffer))
geiser-repl-query-on-kill-p)))))
(defun guix-repl-output-filter (str)
"Filter function suitable for `comint-output-filter-functions'.
This is a replacement for `geiser-repl--output-filter'."
(cond
((string-match-p geiser-guile--prompt-regexp str)
(geiser-autodoc--disinhibit-autodoc)
(when guix-repl-operation-p
(setq guix-repl-operation-p nil)
(run-hooks 'guix-after-repl-operation-hook)
;; Run hooks specific to the current operation type.
(when guix-repl-operation-type
(let ((type-hook (intern
(concat "guix-after-"
(symbol-name guix-repl-operation-type)
"-hook"))))
(setq guix-repl-operation-type nil)
(and (boundp type-hook)
(run-hooks type-hook))))))
((string-match geiser-guile--debugger-prompt-regexp str)
(setq guix-repl-operation-p nil)
(geiser-con--connection-set-debugging geiser-repl--connection
(match-beginning 0))
(geiser-autodoc--disinhibit-autodoc))))
(defun guix-repl-exit (&optional internal no-wait)
"Exit the current Guix REPL.
If INTERNAL is non-nil, exit the internal REPL.
If NO-WAIT is non-nil, do not wait for the REPL process to exit:
send a kill signal to it and return immediately."
(let ((repl (symbol-value (guix-get-repl-buffer-variable internal))))
(when (get-buffer-process repl)
(with-current-buffer repl
(geiser-con--connection-deactivate geiser-repl--connection t)
(comint-kill-subjob)
(unless no-wait
(while (get-buffer-process repl)
(sleep-for 0.1)))))))
(defun guix-get-repl-buffer (&optional internal)
"Return Guix REPL buffer; start REPL if needed.
If INTERNAL is non-nil, return an additional internal REPL."
(guix-start-process-maybe)
(let ((repl (symbol-value (guix-get-repl-buffer-variable internal))))
;; If a new Geiser REPL is started, `geiser-repl--repl' variable may
;; be set to the new value in a Guix REPL, so set it back to a
;; proper value here.
(with-current-buffer repl
(geiser-repl--set-this-buffer-repl repl))
repl))
(defun guix-get-repl-buffer-variable (&optional internal)
"Return the name of a variable with a REPL buffer."
(if internal
'guix-internal-repl-buffer
'guix-repl-buffer))
(defun guix-get-repl-buffer-name (&optional internal)
"Return the name of a REPL buffer."
(if internal
guix-internal-repl-buffer-name
guix-repl-buffer-name))
(defun guix-switch-to-repl (&optional internal)
"Switch to Guix REPL.
If INTERNAL is non-nil (interactively with prefix), switch to the
additional internal REPL if it exists."
(interactive "P")
(geiser-repl--switch-to-buffer (guix-get-repl-buffer internal)))
;;; Evaluating expressions
(defvar guix-operation-buffer nil
"Buffer from which the latest Guix operation was performed.")
(defun guix-make-guile-expression (fun &rest args)
"Return string containing a guile expression for calling FUN with ARGS."
(format "(%S %s)" fun
(mapconcat
(lambda (arg)
(cond
((null arg) "'()")
((or (eq arg t)
;; An ugly hack to separate 'false' from nil
(equal arg 'f)
(keywordp arg))
(concat "#" (prin1-to-string arg t)))
((or (symbolp arg) (listp arg))
(concat "'" (prin1-to-string arg)))
(t (prin1-to-string arg))))
args
" ")))
(defun guix-eval (str &optional wrap)
"Evaluate guile expression STR.
If WRAP is non-nil, wrap STR into (begin ...) form.
Return a list of strings with result values of evaluation."
(with-current-buffer (guix-get-repl-buffer 'internal)
(let* ((wrapped (if wrap (geiser-debug--wrap-region str) str))
(code `(:eval (:scm ,wrapped)))
(ret (geiser-eval--send/wait code)))
(if (geiser-eval--retort-error ret)
(error "Error in evaluating guile expression: %s"
(geiser-eval--retort-output ret))
(cdr (assq 'result ret))))))
(defun guix-eval-read (str &optional wrap)
"Evaluate guile expression STR.
For the meaning of WRAP, see `guix-eval'.
Return elisp expression of the first result value of evaluation."
;; Parsing scheme code with elisp `read' is probably not the best idea.
(read (replace-regexp-in-string
"#f\\|#<unspecified>" "nil"
(replace-regexp-in-string
"#t" "t" (car (guix-eval str wrap))))))
(defun guix-eval-in-repl (str &optional operation-buffer operation-type)
"Switch to Guix REPL and evaluate STR with guile expression there.
If OPERATION-BUFFER is non-nil, it should be a buffer from which
the current operation was performed.
If OPERATION-TYPE is non-nil, it should be a symbol. After
successful executing of the current operation,
`guix-after-OPERATION-TYPE-hook' is called."
(run-hooks 'guix-before-repl-operation-hook)
(setq guix-repl-operation-p t
guix-repl-operation-type operation-type
guix-operation-buffer operation-buffer)
(let ((repl (guix-get-repl-buffer)))
(with-current-buffer repl
(geiser-repl--send str))
(geiser-repl--switch-to-buffer repl)))
(provide 'guix-backend)
;;; guix-backend.el ends here