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;;; emms-info.el --- Info system for EMMS
;; Copyright (C) 2003 Free Software Foundation, Inc.
;; Author: Ulrik Jensen <terryp@daimi.au.dk>
;; Keywords:
;; This file 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 2, or (at your option)
;; any later version.
;; This file 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 Emacs; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
;; Boston, MA 02110-1301 USA
;;; Commentary:
;; This file provides an interface for different methods of reading
;; info about the files that EMMS is playing, and displaying it.
;; To create a method for retrieving info about a file, you create an
;; object like this:
;; (define-emms-info-method emms-info-mp3info
;; :providep 'emms-info-mp3info-providep
;; :get 'emms-info-mp3info-get
;; :set 'emms-info-mp3info-set)
;; Then you register it with emms-info, by adding it to
;; `emms-info-methods-list'.
;; (add-to-list 'emms-info-methods-list 'emms-info-ogg-comment)
;;; Code:
(require 'emms)
(eval-when-compile (require 'cl))
(defvar emms-info-version "0.2 $Revision: 1.16 $"
"EMMS info version string.")
;; $Id: emms-info.el,v 1.16 2005/08/12 17:59:30 xwl Exp $
;; Customizations
(defgroup emms-info nil
"*Info system for EMMS"
:prefix "emms-info-"
:group 'emms)
(defgroup emms-info-methods nil
"*Methods to get info for EMMS-info"
:group 'emms-info
:prefix "emms-info-")
(defcustom emms-info-methods-list nil
"List of info-methods. You need to set this."
:group 'emms-info
:type '(repeat function))
;; Caching
(defcustom emms-info-cache t
"Boolean value, indicating whether or not to use a cache for
info-structures."
:group 'emms-info
:type 'boolean)
(defcustom emms-info-format '("%s - %s" (emms-info-artist emms-info-title))
"Format the info string.
The first element of the list is a string with typical format
instructions, the cdr is a list of functions that get called with
the struct as argument."
:type '(list string (repeat sexp))
:group 'emms-pbi)
(defvar emms-info-cache-hash-table nil
"A hash-table storing the cached info.
Uses tracks as keys and the emms-info structures as
values.")
;; The structure for info about files:
(defstruct emms-info title artist album note year genre file
playing-time playing-time-min playing-time-sec)
;; Interface
(defmacro define-emms-info-method (name &rest alist)
`(defun ,name (action)
(plist-get ',(mapcar (lambda (keyword)
(if (not (keywordp keyword))
(cadr keyword)
(intern (substring (symbol-name keyword) 1))))
alist)
action)))
;; Methods for the cache
(defun emms-info-get-cached (track)
"Return cached info for the track TRACK, nil of no cache."
(if emms-info-cache-hash-table
(gethash track emms-info-cache-hash-table nil)
nil))
(defun emms-info-set-cached (track info)
"Set cached info for TRACK to INFO"
(unless emms-info-cache-hash-table
;; No hash-table yet, create one
(setq emms-info-cache-hash-table (make-hash-table :test 'equal)))
(puthash track info emms-info-cache-hash-table))
;; Retrieve
(defun emms-info-method-for (track)
"Return an info-method suitable for TRACK."
(unless emms-info-methods-list
(error "There are no info-methods defined at all. You should customize `emms-info-methods-alist'."))
;; find an info-method capable of providing info for this file
(let ((curmethod emms-info-methods-list))
(while (and curmethod
(not (funcall (funcall (car curmethod) 'providep) track)))
(setq curmethod (cdr curmethod)))
(when curmethod
(car curmethod))))
(defun emms-info-get (track &optional dont-use-cached)
"Return an emms-info structure representing the track TRACK.
if DONT-USE-CACHED is non-nil, then always read from the file."
;; extend with methods for caching
(let ((method (emms-info-method-for track))
(cached (emms-info-get-cached track)))
(if (or dont-use-cached (not emms-info-cache) (not cached))
;; read from the file
(when method
(let ((readinfo (funcall (funcall method 'get) track)))
(when emms-info-cache
;; save the cache
(emms-info-set-cached track readinfo))
;; return the read version
readinfo))
;; else just use the cached
cached)))
(defun emms-info-set (track info)
"Set the info of the file TRACK to the emms-info structure INFO."
(let ((method (emms-info-method-for track)))
(when method
(when emms-info-cache
(emms-info-set-cached track info))
(funcall (funcall method 'set) track info))))
(defun emms-info-format-info (format struct)
"Take FORMAT and format it with STRUCT.
For the formaz of FORMAT see `emms-info-format')"
(apply 'format (car format)
(mapcar (lambda (func)
(funcall func struct))
(cadr format))))
;; Functions suitable as values of
;; `emms-playlist-get-file-name-function':
(defun emms-info-file-info-song-artist (track)
"Returns a description of TRACK, build from it's comments.
If `emms-info-methods-list' indicates how to retrieve special info
about it, use this. Otherwise returns the name alone."
(if (not (and track (emms-track-name track)))
"Invalid track!"
(if (emms-info-method-for track)
;; read the info
(let ((info (emms-info-get track)))
(if (and info (not (string= (emms-info-artist info) "")) (not (string= (emms-info-title info) "")))
(concat (emms-info-artist info) " - " (emms-info-title info))
(file-name-sans-extension (file-name-nondirectory (emms-track-name track)))))
;; we can't read info for this file, default to the name
(file-name-sans-extension (file-name-nondirectory (emms-track-name track))))))
(provide 'emms-info)
;;; emms-info.el ends here
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