Source

gnus / lisp / nnrss.el

Full commit
   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
;;; nnrss.el --- interfacing with RSS

;; Copyright (C) 2001, 2002, 2003, 2004, 2005,
;;   2006 Free Software Foundation, Inc.

;; Author: Shenghuo Zhu <zsh@cs.rochester.edu>
;; Keywords: RSS

;; This file is part of GNU Emacs.

;; GNU Emacs 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.

;; GNU Emacs 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 Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;;; Code:

(eval-when-compile (require 'cl))

(require 'gnus)
(require 'nnoo)
(require 'nnmail)
(require 'message)
(require 'mm-util)
(require 'gnus-util)
(require 'time-date)
(require 'rfc2231)
(require 'mm-url)
(require 'rfc2047)
(require 'mml)
(eval-when-compile
  (ignore-errors
   (require 'xml)))
(eval '(require 'xml))

(nnoo-declare nnrss)

(defvoo nnrss-directory (nnheader-concat gnus-directory "rss/")
  "Where nnrss will save its files.")

;; (group max rss-url)
(defvoo nnrss-server-data nil)

;; (num timestamp url subject author date extra)
(defvoo nnrss-group-data nil)
(defvoo nnrss-group-max 0)
(defvoo nnrss-group-min 1)
(defvoo nnrss-group nil)
(defvoo nnrss-group-hashtb nil)
(defvoo nnrss-status-string "")

(defconst nnrss-version "nnrss 1.0")

(defvar nnrss-group-alist '()
  "List of RSS addresses.")

(defvar nnrss-use-local nil)

(defvar nnrss-description-field 'X-Gnus-Description
  "Field name used for DESCRIPTION.
To use the description in headers, put this name into `nnmail-extra-headers'.")

(defvar nnrss-url-field 'X-Gnus-Url
  "Field name used for URL.
To use the description in headers, put this name into `nnmail-extra-headers'.")

(defvar nnrss-content-function nil
  "A function which is called in `nnrss-request-article'.
The arguments are (ENTRY GROUP ARTICLE).
ENTRY is the record of the current headline.  GROUP is the group name.
ARTICLE is the article number of the current headline.")

(defvar nnrss-file-coding-system mm-universal-coding-system
  "Coding system used when reading and writing files.")

(defvar nnrss-compatible-encoding-alist '((iso-8859-1 . windows-1252))
  "Alist of encodings and those supersets.
The cdr of each element is used to decode data if it is available when
the car is what the data specify as the encoding.  Or, the car is used
for decoding when the cdr that the data specify is not available.")

(defvar nnrss-wash-html-in-text-plain-parts nil
  "*Non-nil means render text in text/plain parts as HTML.
The function specified by the `mm-text-html-renderer' variable will be
used to render text.  If it is nil, text will simply be folded.")

(nnoo-define-basics nnrss)

;;; Interface functions

(defsubst nnrss-format-string (string)
  (gnus-replace-in-string string " *\n *" " "))

(defun nnrss-decode-group-name (group)
  (if (and group (mm-coding-system-p 'utf-8))
      (setq group (mm-decode-coding-string group 'utf-8))
    group))

(deffoo nnrss-retrieve-headers (articles &optional group server fetch-old)
  (setq group (nnrss-decode-group-name group))
  (nnrss-possibly-change-group group server)
  (let (e)
    (save-excursion
      (set-buffer nntp-server-buffer)
      (erase-buffer)
      (dolist (article articles)
	(if (setq e (assq article nnrss-group-data))
	    (insert (number-to-string (car e)) "\t" ;; number
		    ;; subject
		    (or (nth 3 e) "")
		    "\t"
		    ;; from
		    (or (nth 4 e) "(nobody)")
		    "\t"
		    ;; date
		    (or (nth 5 e) "")
		    "\t"
		    ;; id
		    (format "<%d@%s.nnrss>" (car e) group)
		    "\t"
		    ;; refs
		    "\t"
		    ;; chars
		    "-1" "\t"
		    ;; lines
		    "-1" "\t"
		    ;; Xref
		    "" "\t"
		    (if (and (nth 6 e)
			     (memq nnrss-description-field
				   nnmail-extra-headers))
			(concat (symbol-name nnrss-description-field)
				": "
				(nnrss-format-string (nth 6 e))
				"\t")
		      "")
		    (if (and (nth 2 e)
			     (memq nnrss-url-field
				   nnmail-extra-headers))
			(concat (symbol-name nnrss-url-field)
				": "
				(nnrss-format-string (nth 2 e))
				"\t")
		      "")
		    "\n")))))
  'nov)

(deffoo nnrss-request-group (group &optional server dont-check)
  (setq group (nnrss-decode-group-name group))
  (nnheader-message 6 "nnrss: Requesting %s..." group)
  (nnrss-possibly-change-group group server)
  (prog1
      (if dont-check
	  t
	(nnrss-check-group group server)
	(nnheader-report 'nnrss "Opened group %s" group)
	(nnheader-insert
	 "211 %d %d %d %s\n" nnrss-group-max nnrss-group-min nnrss-group-max
	 (prin1-to-string group)
	 t))
    (nnheader-message 6 "nnrss: Requesting %s...done" group)))

(deffoo nnrss-close-group (group &optional server)
  t)

(eval-when-compile
  (defvar mm-text-html-renderer)
  (defvar mm-text-html-washer-alist))

(deffoo nnrss-request-article (article &optional group server buffer)
  (setq group (nnrss-decode-group-name group))
  (when (stringp article)
    (setq article (if (string-match "\\`<\\([0-9]+\\)@" article)
		      (string-to-number (match-string 1 article))
		    0)))
  (nnrss-possibly-change-group group server)
  (let ((e (assq article nnrss-group-data))
	(nntp-server-buffer (or buffer nntp-server-buffer))
	post err)
    (when e
      (with-current-buffer nntp-server-buffer
	(erase-buffer)
	(if group
	    (insert "Newsgroups: " group "\n"))
	(if (nth 3 e)
	    (insert "Subject: " (nth 3 e) "\n"))
	(if (nth 4 e)
	    (insert "From: " (nth 4 e) "\n"))
	(if (nth 5 e)
	    (insert "Date: " (nnrss-format-string (nth 5 e)) "\n"))
	(let ((header (buffer-string))
	      (text (nth 6 e))
	      (link (nth 2 e))
	      (enclosure (nth 7 e))
	      (comments (nth 8 e))
	      ;; Enable encoding of Newsgroups header in XEmacs.
	      (default-enable-multibyte-characters t)
	      (rfc2047-header-encoding-alist
	       (if (mm-coding-system-p 'utf-8)
		   (cons '("Newsgroups" . utf-8)
			 rfc2047-header-encoding-alist)
		 rfc2047-header-encoding-alist))
	      rfc2047-encode-encoded-words body fn)
	  (when (or text link enclosure comments)
	    (insert "\n")
	    (insert "<#multipart type=alternative>\n"
		    "<#part type=\"text/plain\">\n")
	    (setq body (point))
	    (when text
	      (insert text)
	      (goto-char body)
	      (if (and nnrss-wash-html-in-text-plain-parts
		       (progn
			 (require 'mm-view)
			 (setq fn (or (cdr (assq mm-text-html-renderer
						 mm-text-html-washer-alist))
				      mm-text-html-renderer))))
		  (progn
		    (narrow-to-region body (point-max))
		    (if (functionp fn)
			(funcall fn)
		      (apply (car fn) (cdr fn)))
		    (widen)
		    (goto-char body)
		    (re-search-forward "[^\t\n ]" nil t)
		    (beginning-of-line)
		    (delete-region body (point))
		    (goto-char (point-max))
		    (skip-chars-backward "\t\n ")
		    (end-of-line)
		    (delete-region (point) (point-max))
		    (insert "\n"))
		(while (re-search-forward "\n+" nil t)
		  (replace-match " "))
		(goto-char body)
		;; See `nnrss-check-group', which inserts "<br /><br />".
		(when (search-forward "<br /><br />" nil t)
		  (if (eobp)
		      (replace-match "\n")
		    (replace-match "\n\n")))
		(unless (eobp)
		  (let ((fill-column default-fill-column)
			(window (get-buffer-window nntp-server-buffer)))
		    (when window
		      (setq fill-column
			    (max 1 (/ (* (window-width window) 7) 8))))
		    (fill-region (point) (point-max))
		    (goto-char (point-max))
		    ;; XEmacs version of `fill-region' inserts newline.
		    (unless (bolp)
		      (insert "\n")))))
	      (when (or link enclosure)
		(insert "\n")))
	    (when link
	      (insert link "\n"))
	    (when enclosure
	      (insert (car enclosure) " "
		      (nth 2 enclosure) " "
		      (nth 3 enclosure) "\n"))
	    (when comments
	      (insert comments "\n"))
	    (setq body (buffer-substring body (point)))
	    (insert "<#/part>\n"
		    "<#part type=\"text/html\">\n"
		    "<html><head></head><body>\n")
	    (when text
	      (insert text "\n"))
	    (when link
	      (insert "<p><a href=\"" link "\">link</a></p>\n"))
	    (when enclosure
	      (insert "<p><a href=\"" (car enclosure) "\">"
		      (cadr enclosure) "</a> " (nth 2 enclosure)
		      " " (nth 3 enclosure) "</p>\n"))
	    (when comments
	      (insert "<p><a href=\"" comments "\">comments</a></p>\n"))
	    (insert "</body></html>\n"
		    "<#/part>\n"
		    "<#/multipart>\n"))
	  (condition-case nil
	      (mml-to-mime)
	    (error
	     (erase-buffer)
	     (insert header
		     "Content-Type: text/plain; charset=gnus-decoded\n"
		     "Content-Transfer-Encoding: 8bit\n\n"
		     body)
	     (nnheader-message
	      3 "Warning - there might be invalid characters"))))
	(goto-char (point-min))
	(search-forward "\n\n")
	(forward-line -1)
	(insert (format "Message-ID: <%d@%s.nnrss>\n"
			(car e)
			(let ((rfc2047-encoding-type 'mime)
			      rfc2047-encode-max-chars)
			  (rfc2047-encode-string
			   (gnus-replace-in-string group "[\t\n ]+" "_")))))
	(when nnrss-content-function
	  (funcall nnrss-content-function e group article))))
    (cond
     (err
      (nnheader-report 'nnrss err))
     ((not e)
      (nnheader-report 'nnrss "no such id: %d" article))
     (t
      (nnheader-report 'nnrss "article %s retrieved" (car e))
      ;; we return the article number.
      (cons nnrss-group (car e))))))

(deffoo nnrss-request-list (&optional server)
  (nnrss-possibly-change-group nil server)
  (nnrss-generate-active)
  t)

(deffoo nnrss-open-server (server &optional defs connectionless)
  (nnrss-read-server-data server)
  (nnoo-change-server 'nnrss server defs)
  t)

(deffoo nnrss-request-expire-articles
    (articles group &optional server force)
  (setq group (nnrss-decode-group-name group))
  (nnrss-possibly-change-group group server)
  (let (e days not-expirable changed)
    (dolist (art articles)
      (if (and (setq e (assq art nnrss-group-data))
	       (nnmail-expired-article-p
		group
		(if (listp (setq days (nth 1 e))) days
		  (days-to-time (- days (time-to-days '(0 0)))))
		force))
	  (setq nnrss-group-data (delq e nnrss-group-data)
		changed t)
	(push art not-expirable)))
    (if changed
	(nnrss-save-group-data group server))
    not-expirable))

(deffoo nnrss-request-delete-group (group &optional force server)
  (setq group (nnrss-decode-group-name group))
  (nnrss-possibly-change-group group server)
  (let (elem)
    ;; There may be two or more entries in `nnrss-group-alist' since
    ;; this function didn't delete them formerly.
    (while (setq elem (assoc group nnrss-group-alist))
      (setq nnrss-group-alist (delq elem nnrss-group-alist))))
  (setq nnrss-server-data
	(delq (assoc group nnrss-server-data) nnrss-server-data))
  (nnrss-save-server-data server)
  (ignore-errors
   (delete-file (nnrss-make-filename group server)))
  t)

(deffoo nnrss-request-list-newsgroups (&optional server)
  (nnrss-possibly-change-group nil server)
  (save-excursion
    (set-buffer nntp-server-buffer)
    (erase-buffer)
    (dolist (elem nnrss-group-alist)
      (if (third elem)
	  (insert (car elem) "\t" (third elem) "\n"))))
  t)

(nnoo-define-skeleton nnrss)

;;; Internal functions
(eval-when-compile (defun xml-rpc-method-call (&rest args)))

(defun nnrss-get-encoding ()
  "Return an encoding attribute specified in the current xml contents.
If `nnrss-compatible-encoding-alist' specifies the compatible encoding,
it is used instead.  If the xml contents doesn't specify the encoding,
return `utf-8' which is the default encoding for xml if it is available,
otherwise return nil."
  (goto-char (point-min))
  (if (re-search-forward
       "<\\?[^>]*encoding=\\(\"\\([^\">]+\\)\"\\|'\\([^'>]+\\)'\\)"
       nil t)
      (let ((encoding (intern (downcase (or (match-string 2)
					    (match-string 3))))))
	(or
	 (mm-coding-system-p (cdr (assq encoding
					nnrss-compatible-encoding-alist)))
	 (mm-coding-system-p encoding)
	 (mm-coding-system-p (car (rassq encoding
					 nnrss-compatible-encoding-alist)))))
    (mm-coding-system-p 'utf-8)))

(defun nnrss-fetch (url &optional local)
  "Fetch URL and put it in a the expected Lisp structure."
  (mm-with-unibyte-buffer
    ;;some CVS versions of url.el need this to close the connection quickly
    (let (cs xmlform htmlform)
      ;; bit o' work necessary for w3 pre-cvs and post-cvs
      (if local
	  (let ((coding-system-for-read 'binary))
	    (insert-file-contents url))
	;; FIXME: shouldn't binding `coding-system-for-read' be moved
	;; to `mm-url-insert'?
	(let ((coding-system-for-read 'binary))
	  (condition-case err
	      (mm-url-insert url)
	    (error (if (or debug-on-quit debug-on-error)
		       (signal (car err) (cdr err))
		     (message "nnrss: Failed to fetch %s" url))))))
      (nnheader-remove-cr-followed-by-lf)
      ;; Decode text according to the encoding attribute.
      (when (setq cs (nnrss-get-encoding))
	(mm-decode-coding-region (point-min) (point-max) cs)
	(mm-enable-multibyte))
      (goto-char (point-min))

      ;; Because xml-parse-region can't deal with anything that isn't
      ;; xml and w3-parse-buffer can't deal with some xml, we have to
      ;; parse with xml-parse-region first and, if that fails, parse
      ;; with w3-parse-buffer.  Yuck.  Eventually, someone should find out
      ;; why w3-parse-buffer fails to parse some well-formed xml and
      ;; fix it.

      (condition-case err1
	  (setq xmlform (xml-parse-region (point-min) (point-max)))
	(error
	 (condition-case err2
	     (setq htmlform (caddar (w3-parse-buffer
				     (current-buffer))))
	   (error
	    (message "\
nnrss: %s: Not valid XML %s and w3-parse doesn't work %s"
		     url err1 err2)))))
      (if htmlform
	  htmlform
	xmlform))))

(defun nnrss-possibly-change-group (&optional group server)
  (when (and server
	     (not (nnrss-server-opened server)))
    (nnrss-open-server server))
  (when (and group (not (equal group nnrss-group)))
    (nnrss-read-group-data group server)
    (setq nnrss-group group)))

(defvar nnrss-extra-categories '(nnrss-snarf-moreover-categories))

(defun nnrss-generate-active ()
  (when (y-or-n-p "Fetch extra categories? ")
    (dolist (func nnrss-extra-categories)
      (funcall func)))
  (save-excursion
    (set-buffer nntp-server-buffer)
    (erase-buffer)
    (dolist (elem nnrss-group-alist)
      (insert (prin1-to-string (car elem)) " 0 1 y\n"))
    (dolist (elem nnrss-server-data)
      (unless (assoc (car elem) nnrss-group-alist)
	(insert (prin1-to-string (car elem)) " 0 1 y\n")))))

(eval-and-compile (autoload 'timezone-parse-date "timezone"))

(defun nnrss-normalize-date (date)
  "Return a date string of DATE in the RFC822 style.
This function handles the ISO 8601 date format described in
<URL:http://www.w3.org/TR/NOTE-datetime>, and also the RFC822 style
which RSS 2.0 allows."
  (let (case-fold-search vector year month day time zone cts)
    (cond ((null date))
	  ;; RFC822
	  ((string-match " [0-9]+ " date)
	   (setq vector (timezone-parse-date date)
		 year (string-to-number (aref vector 0)))
	   (when (>= year 1969)
	     (setq month (string-to-number (aref vector 1))
		   day (string-to-number (aref vector 2)))
	     (unless (>= (length (setq time (aref vector 3))) 3)
	       (setq time "00:00:00"))
	     (when (and (setq zone (aref vector 4))
			(not (string-match "\\`[A-Z+-]" zone)))
	       (setq zone nil))))
	  ;; ISO 8601
	  ((string-match
	    (eval-when-compile
	      (concat
	       ;; 1. year
	       "\\(199[0-9]\\|20[0-9][0-9]\\)"
	       "\\(-"
	       ;; 3. month
	       "\\([01][0-9]\\)"
	       "\\(-"
	       ;; 5. day
	       "\\([0-3][0-9]\\)"
	       "\\)?\\)?\\(T"
	       ;; 7. hh:mm
	       "\\([012][0-9]:[0-5][0-9]\\)"
	       "\\("
	       ;; 9. :ss
	       "\\(:[0-5][0-9]\\)"
	       "\\(\\.[0-9]+\\)?\\)?\\)?"
	       ;; 13+14,15,16. zone
	       "\\(\\(\\([+-][012][0-9]\\):\\([0-5][0-9]\\)\\)"
	       "\\|\\([+-][012][0-9][0-5][0-9]\\)"
	       "\\|\\(Z\\)\\)?"))
	    date)
	   (setq year (string-to-number (match-string 1 date))
		 month (string-to-number (or (match-string 3 date) "1"))
		 day (string-to-number (or (match-string 5 date) "1"))
		 time (if (match-beginning 9)
			  (substring date (match-beginning 7) (match-end 9))
			(concat (or (match-string 7 date) "00:00") ":00"))
		 zone (cond ((match-beginning 13)
			     (concat (match-string 13 date)
				     (match-string 14 date)))
			    ((match-beginning 16) ;; Z
			     "+0000")
			    (t ;; nil if zone is not provided.
			     (match-string 15 date))))))
    (if month
	(progn
	  (setq cts (current-time-string (encode-time 0 0 0 day month year)))
	  (format "%s, %02d %s %04d %s%s"
		  (substring cts 0 3) day (substring cts 4 7) year time
		  (if zone
		      (concat " " zone)
		    "")))
      (message-make-date))))

;;; data functions

(defun nnrss-read-server-data (server)
  (setq nnrss-server-data nil)
  (let ((file (nnrss-make-filename "nnrss" server)))
    (when (file-exists-p file)
      ;; In Emacs 21.3 and earlier, `load' doesn't support non-ASCII
      ;; file names.  So, we use `insert-file-contents' instead.
      (mm-with-multibyte-buffer
	(let ((coding-system-for-read nnrss-file-coding-system)
	      (file-name-coding-system nnmail-pathname-coding-system))
	  (insert-file-contents file)
	  (eval-region (point-min) (point-max)))))))

(defun nnrss-save-server-data (server)
  (gnus-make-directory nnrss-directory)
  (let ((coding-system-for-write nnrss-file-coding-system)
	(file-name-coding-system nnmail-pathname-coding-system))
    (with-temp-file (nnrss-make-filename "nnrss" server)
      (insert (format ";; -*- coding: %s; -*-\n"
		      nnrss-file-coding-system))
      (gnus-prin1 `(setq nnrss-group-alist ',nnrss-group-alist))
      (insert "\n")
      (gnus-prin1 `(setq nnrss-server-data ',nnrss-server-data)))))

(defun nnrss-read-group-data (group server)
  (setq nnrss-group-data nil)
  (setq nnrss-group-hashtb (gnus-make-hashtable))
  (let ((pair (assoc group nnrss-server-data)))
    (setq nnrss-group-max (or (cadr pair) 0))
    (setq nnrss-group-min (+ nnrss-group-max 1)))
  (let ((file (nnrss-make-filename group server)))
    (when (file-exists-p file)
      ;; In Emacs 21.3 and earlier, `load' doesn't support non-ASCII
      ;; file names.  So, we use `insert-file-contents' instead.
      (mm-with-multibyte-buffer
	(let ((coding-system-for-read nnrss-file-coding-system)
	      (file-name-coding-system nnmail-pathname-coding-system))
	  (insert-file-contents file)
	  (eval-region (point-min) (point-max))))
      (dolist (e nnrss-group-data)
	(gnus-sethash (or (nth 2 e) (nth 6 e)) t nnrss-group-hashtb)
	(when (and (car e) (> nnrss-group-min (car e)))
	  (setq nnrss-group-min (car e)))
	(when (and (car e) (< nnrss-group-max (car e)))
	  (setq nnrss-group-max (car e)))))))

(defun nnrss-save-group-data (group server)
  (gnus-make-directory nnrss-directory)
  (let ((coding-system-for-write nnrss-file-coding-system)
	(file-name-coding-system nnmail-pathname-coding-system))
    (with-temp-file (nnrss-make-filename group server)
      (insert (format ";; -*- coding: %s; -*-\n"
		      nnrss-file-coding-system))
      (gnus-prin1 `(setq nnrss-group-data ',nnrss-group-data)))))

(defun nnrss-make-filename (name server)
  (expand-file-name
   (nnrss-translate-file-chars
    (concat name
	    (and server
		 (not (equal server ""))
		 "-")
	    server
	    ".el"))
   nnrss-directory))

(gnus-add-shutdown 'nnrss-close 'gnus)

(defun nnrss-close ()
  "Clear internal nnrss variables."
  (setq nnrss-group-data nil
	nnrss-server-data nil
	nnrss-group-hashtb nil
	nnrss-group-alist nil))

;;; URL interface

(defun nnrss-no-cache (url)
  "")

(defun nnrss-insert-w3 (url)
  (mm-with-unibyte-current-buffer
    (condition-case err
	(mm-url-insert url)
      (error (if (or debug-on-quit debug-on-error)
		 (signal (car err) (cdr err))
	       (message "nnrss: Failed to fetch %s" url))))))

(defun nnrss-decode-entities-string (string)
  (if string
      (mm-with-multibyte-buffer
	(insert string)
	(mm-url-decode-entities-nbsp)
	(buffer-string))))

(defalias 'nnrss-insert 'nnrss-insert-w3)

(defun nnrss-mime-encode-string (string)
  (mm-with-multibyte-buffer
    (insert string)
    (mm-url-decode-entities-nbsp)
    (goto-char (point-min))
    (while (re-search-forward "[\t\n ]+" nil t)
      (replace-match " "))
    (goto-char (point-min))
    (skip-chars-forward " ")
    (delete-region (point-min) (point))
    (goto-char (point-max))
    (skip-chars-forward " ")
    (delete-region (point) (point-max))
    (let ((rfc2047-encoding-type 'mime)
	  rfc2047-encode-max-chars)
      (rfc2047-encode-region (point-min) (point-max)))
    (goto-char (point-min))
    (while (search-forward "\n" nil t)
      (delete-backward-char 1))
    (buffer-string)))

;;; Snarf functions

(defun nnrss-check-group (group server)
  (let (file xml subject url extra changed author date feed-subject
	     enclosure comments rss-ns rdf-ns content-ns dc-ns)
    (if (and nnrss-use-local
	     (file-exists-p (setq file (expand-file-name
					(nnrss-translate-file-chars
					 (concat group ".xml"))
					nnrss-directory))))
	(setq xml (nnrss-fetch file t))
      (setq url (or (nth 2 (assoc group nnrss-server-data))
		    (second (assoc group nnrss-group-alist))))
      (unless url
	(setq url
	      (cdr
	       (assoc 'href
		      (nnrss-discover-feed
		       (read-string
			(format "URL to search for %s: " group) "http://")))))
	(let ((pair (assoc group nnrss-server-data)))
	  (if pair
	      (setcdr (cdr pair) (list url))
	    (push (list group nnrss-group-max url) nnrss-server-data)))
	(setq changed t))
      (setq xml (nnrss-fetch url)))
    ;; See
    ;; http://feeds.archive.org/validator/docs/howto/declare_namespaces.html
    ;; for more RSS namespaces.
    (setq dc-ns (nnrss-get-namespace-prefix xml "http://purl.org/dc/elements/1.1/")
	  rdf-ns (nnrss-get-namespace-prefix xml "http://www.w3.org/1999/02/22-rdf-syntax-ns#")
	  rss-ns (nnrss-get-namespace-prefix xml "http://purl.org/rss/1.0/")
	  content-ns (nnrss-get-namespace-prefix xml "http://purl.org/rss/1.0/modules/content/"))
    (dolist (item (nreverse (nnrss-find-el (intern (concat rss-ns "item")) xml)))
      (when (and (listp item)
		 (string= (concat rss-ns "item") (car item))
		 (if (setq url (nnrss-decode-entities-string
				(nnrss-node-text rss-ns 'link (cddr item))))
		     (not (gnus-gethash url nnrss-group-hashtb))
		   (setq extra (or (nnrss-node-text content-ns 'encoded item)
				   (nnrss-node-text rss-ns 'description item)))
		   (not (gnus-gethash extra nnrss-group-hashtb))))
	(setq subject (nnrss-node-text rss-ns 'title item))
	(setq extra (or extra
			(nnrss-node-text content-ns 'encoded item)
			(nnrss-node-text rss-ns 'description item)))
	(if (setq feed-subject (nnrss-node-text dc-ns 'subject item))
	    (setq extra (concat feed-subject "<br /><br />" extra)))
	(setq author (or (nnrss-node-text rss-ns 'author item)
			 (nnrss-node-text dc-ns 'creator item)
			 (nnrss-node-text dc-ns 'contributor item)))
	(setq date (nnrss-normalize-date
		    (or (nnrss-node-text dc-ns 'date item)
			(nnrss-node-text rss-ns 'pubDate item))))
	(setq comments (nnrss-node-text rss-ns 'comments item))
	(when (setq enclosure (cadr (assq (intern (concat rss-ns "enclosure")) item)))
	  (let ((url (cdr (assq 'url enclosure)))
		(len (cdr (assq 'length enclosure)))
		(type (cdr (assq 'type enclosure)))
		(name))
	    (setq len
		  (if (and len (integerp (setq len (string-to-number len))))
		      ;; actually already in `ls-lisp-format-file-size' but
		      ;; probably not worth to require it for one function
		      (do ((size (/ len 1.0) (/ size 1024.0))
			   (post-fixes (list "" "k" "M" "G" "T" "P" "E")
				       (cdr post-fixes)))
			  ((< size 1024)
			   (format "%.1f%s" size (car post-fixes))))
		    "0"))
	    (setq url (or url ""))
	    (setq name (if (string-match "/\\([^/]*\\)$" url)
			   (match-string 1 url)
			 "file"))
	    (setq type (or type ""))
	    (setq enclosure (list url name len type))))
	(push
	 (list
	  (incf nnrss-group-max)
	  (current-time)
	  url
	  (and subject (nnrss-mime-encode-string subject))
	  (and author (nnrss-mime-encode-string author))
	  date
	  (and extra (nnrss-decode-entities-string extra))
	  enclosure
	  comments)
	 nnrss-group-data)
	(gnus-sethash (or url extra) t nnrss-group-hashtb)
	(setq changed t))
      (setq extra nil))
    (when changed
      (nnrss-save-group-data group server)
      (let ((pair (assoc group nnrss-server-data)))
	(if pair
	    (setcar (cdr pair) nnrss-group-max)
	  (push (list group nnrss-group-max) nnrss-server-data)))
      (nnrss-save-server-data server))))

(defun nnrss-opml-import (opml-file)
  "OPML subscriptions import.
Read the file and attempt to subscribe to each Feed in the file."
  (interactive "fImport file: ")
  (mapc
   (lambda (node)
     (let ((xmlurl (cdr (assq 'xmlUrl (cadr node)))))
       (when (and xmlurl
		  (not (string-match "\\`[\t ]*\\'" xmlurl))
		  (prog1
		      (y-or-n-p (format "Subscribe to %s " xmlurl))
		    (message "")))
	 (condition-case err
	     (progn
	       (gnus-group-make-rss-group xmlurl)
	       (forward-line 1))
	   (error
	    (message
	     "Failed to subscribe to %s (%s); type any key to continue: "
	     xmlurl
	     (error-message-string err))
	    (let ((echo-keystrokes 0))
	      (read-char)))))))
   (nnrss-find-el 'outline
		  (mm-with-multibyte-buffer
		    (insert-file-contents opml-file)
		    (xml-parse-region (point-min) (point-max))))))

(defun nnrss-opml-export ()
  "OPML subscription export.
Export subscriptions to a buffer in OPML Format."
  (interactive)
  (with-current-buffer (get-buffer-create "*OPML Export*")
    (mm-set-buffer-file-coding-system 'utf-8)
    (insert "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
	    "<!-- OPML generated by Emacs Gnus' nnrss.el -->\n"
	    "<opml version=\"1.1\">\n"
	    "  <head>\n"
	    "    <title>mySubscriptions</title>\n"
	    "    <dateCreated>" (format-time-string "%a, %d %b %Y %T %z")
	    "</dateCreated>\n"
	    "    <ownerEmail>" user-mail-address "</ownerEmail>\n"
	    "    <ownerName>" (user-full-name) "</ownerName>\n"
	    "  </head>\n"
	    "  <body>\n")
    (dolist (sub nnrss-group-alist)
      (insert "    <outline text=\"" (car sub)
	      "\" xmlUrl=\"" (cadr sub) "\"/>\n"))
    (insert "  </body>\n"
	    "</opml>\n"))
  (pop-to-buffer "*OPML Export*")
  (when (fboundp 'sgml-mode)
    (sgml-mode)))

(defun nnrss-generate-download-script ()
  "Generate a download script in the current buffer.
It is useful when `(setq nnrss-use-local t)'."
  (interactive)
  (insert "#!/bin/sh\n")
  (insert "WGET=wget\n")
  (insert "RSSDIR='" (expand-file-name nnrss-directory) "'\n")
  (dolist (elem nnrss-server-data)
    (let ((url (or (nth 2 elem)
		   (second (assoc (car elem) nnrss-group-alist)))))
      (insert "$WGET -q -O \"$RSSDIR\"/'"
	      (nnrss-translate-file-chars (concat (car elem) ".xml"))
	      "' '" url "'\n"))))

(defun nnrss-translate-file-chars (name)
  (let ((nnheader-file-name-translation-alist
	 (append nnheader-file-name-translation-alist '((?' . ?_)))))
    (nnheader-translate-file-chars name)))

(defvar nnrss-moreover-url
  "http://w.moreover.com/categories/category_list_rss.html"
  "The url of moreover.com categories.")

(defun nnrss-snarf-moreover-categories ()
  "Snarf RSS links from moreover.com."
  (interactive)
  (let (category name url changed)
    (with-temp-buffer
      (nnrss-insert nnrss-moreover-url)
      (goto-char (point-min))
      (while (re-search-forward
	      "<a name=\"\\([^\"]+\\)\">\\|<a href=\"\\(http://[^\"]*moreover\\.com[^\"]+page\\?c=\\([^\"&]+\\)&o=rss\\)" nil t)
	(if (match-string 1)
	    (setq category (match-string 1))
	  (setq url (match-string 2)
		name (mm-url-decode-entities-string
		      (rfc2231-decode-encoded-string
		       (match-string 3))))
	  (if category
	      (setq name (concat category "." name)))
	  (unless (assoc name nnrss-server-data)
	    (setq changed t)
	    (push (list name 0 url) nnrss-server-data)))))
    (if changed
	(nnrss-save-server-data ""))))

(defun nnrss-node-text (namespace local-name element)
  (let* ((node (assq (intern (concat namespace (symbol-name local-name)))
		     element))
	 (text (if (and node (listp node))
		   (nnrss-node-just-text node)
		 node))
	 (cleaned-text (if text
			   (gnus-replace-in-string
			    (gnus-replace-in-string
			     text "^[\000-\037\177]+\\|^ +\\| +$" "")
			    "\r\n" "\n"))))
    (if (string-equal "" cleaned-text)
	nil
      cleaned-text)))

(defun nnrss-node-just-text (node)
  (if (and node (listp node))
      (mapconcat 'nnrss-node-just-text (cddr node) " ")
    node))

(defun nnrss-find-el (tag data &optional found-list)
  "Find the all matching elements in the data.
Careful with this on large documents!"
  (when (consp data)
    (dolist (bit data)
      (when (car-safe bit)
	(when (equal tag (car bit))
	  ;; Old xml.el may return a list of string.
	  (when (and (consp (caddr bit))
		     (stringp (caaddr bit)))
	    (setcar (cddr bit) (caaddr bit)))
	  (setq found-list
		(append found-list
			(list bit))))
	(if (and (consp (car-safe (caddr bit)))
		 (not (stringp (caddr bit))))
	    (setq found-list
		  (append found-list
			  (nnrss-find-el
			   tag (caddr bit))))
	  (setq found-list
		(append found-list
			(nnrss-find-el
			 tag (cddr bit))))))))
  found-list)

(defun nnrss-rsslink-p (el)
  "Test if the element we are handed is an RSS autodiscovery link."
  (and (eq (car-safe el) 'link)
       (string-equal (cdr (assoc 'rel (cadr el))) "alternate")
       (or (string-equal (cdr (assoc 'type (cadr el)))
			 "application/rss+xml")
	   (string-equal (cdr (assoc 'type (cadr el))) "text/xml"))))

(defun nnrss-get-rsslinks (data)
  "Extract the <link> elements that are links to RSS from the parsed data."
  (delq nil (mapcar
	     (lambda (el)
	       (if (nnrss-rsslink-p el) el))
	     (nnrss-find-el 'link data))))

(defun nnrss-extract-hrefs (data)
  "Recursively extract hrefs from a page's source.
DATA should be the output of `xml-parse-region' or
`w3-parse-buffer'."
  (mapcar (lambda (ahref)
	    (cdr (assoc 'href (cadr ahref))))
	  (nnrss-find-el 'a data)))

(defmacro nnrss-match-macro (base-uri item onsite-list offsite-list)
  `(cond ((or (string-match (concat "^" ,base-uri) ,item)
	      (not (string-match "://" ,item)))
	  (setq ,onsite-list (append ,onsite-list (list ,item))))
	 (t (setq ,offsite-list (append ,offsite-list (list ,item))))))

(defun nnrss-order-hrefs (base-uri hrefs)
  "Given a list of hrefs, sort them using the following priorities:
  1. links ending in .rss
  2. links ending in .rdf
  3. links ending in .xml
  4. links containing the above
  5. offsite links

BASE-URI is used to determine the location of the links and
whether they are `offsite' or `onsite'."
  (let (rss-onsite-end  rdf-onsite-end  xml-onsite-end
	rss-onsite-in   rdf-onsite-in   xml-onsite-in
	rss-offsite-end rdf-offsite-end xml-offsite-end
	rss-offsite-in  rdf-offsite-in  xml-offsite-in)
    (dolist (href hrefs)
      (cond ((null href))
	    ((string-match "\\.rss$" href)
	     (nnrss-match-macro
	      base-uri href rss-onsite-end rss-offsite-end))
	    ((string-match "\\.rdf$" href)
	     (nnrss-match-macro
	      base-uri href rdf-onsite-end rdf-offsite-end))
	    ((string-match "\\.xml$" href)
	     (nnrss-match-macro
	      base-uri href xml-onsite-end xml-offsite-end))
	    ((string-match "rss" href)
	     (nnrss-match-macro
	      base-uri href rss-onsite-in rss-offsite-in))
	    ((string-match "rdf" href)
	     (nnrss-match-macro
	      base-uri href rdf-onsite-in rdf-offsite-in))
	    ((string-match "xml" href)
	     (nnrss-match-macro
	      base-uri href xml-onsite-in xml-offsite-in))))
    (append
     rss-onsite-end  rdf-onsite-end  xml-onsite-end
     rss-onsite-in   rdf-onsite-in   xml-onsite-in
     rss-offsite-end rdf-offsite-end xml-offsite-end
     rss-offsite-in rdf-offsite-in xml-offsite-in)))

(defun nnrss-discover-feed (url)
  "Given a page, find an RSS feed using Mark Pilgrim's
`ultra-liberal rss locator' (http://diveintomark.org/2002/08/15.html)."

  (let ((parsed-page (nnrss-fetch url)))

;;    1. if this url is the rss, use it.
    (if (nnrss-rss-p parsed-page)
	(let ((rss-ns (nnrss-get-namespace-prefix parsed-page "http://purl.org/rss/1.0/")))
	  (nnrss-rss-title-description rss-ns parsed-page url))

;;    2. look for the <link rel="alternate"
;;    type="application/rss+xml" and use that if it is there.
      (let ((links (nnrss-get-rsslinks parsed-page)))
	(if links
	    (let* ((xml (nnrss-fetch
			 (cdr (assoc 'href (cadar links)))))
		   (rss-ns (nnrss-get-namespace-prefix xml "http://purl.org/rss/1.0/")))
	      (nnrss-rss-title-description rss-ns xml (cdr (assoc 'href (cadar links)))))

;;    3. look for links on the site in the following order:
;;       - onsite links ending in .rss, .rdf, or .xml
;;       - onsite links containing any of the above
;;       - offsite links ending in .rss, .rdf, or .xml
;;       - offsite links containing any of the above
	  (let* ((base-uri (progn (string-match ".*://[^/]+/?" url)
				  (match-string 0 url)))
		 (hrefs (nnrss-order-hrefs
			 base-uri (nnrss-extract-hrefs parsed-page)))
		 (rss-link nil))
	    (while (and (eq rss-link nil) (not (eq hrefs nil)))
	      (let ((href-data (nnrss-fetch (car hrefs))))
		(if (nnrss-rss-p href-data)
		    (let* ((rss-ns (nnrss-get-namespace-prefix href-data "http://purl.org/rss/1.0/")))
		      (setq rss-link (nnrss-rss-title-description
				      rss-ns href-data (car hrefs))))
		  (setq hrefs (cdr hrefs)))))
	    (if rss-link rss-link

;;    4. check syndic8
	      (nnrss-find-rss-via-syndic8 url))))))))

(defun nnrss-find-rss-via-syndic8 (url)
  "Query syndic8 for the rss feeds it has for URL."
  (if (not (locate-library "xml-rpc"))
      (progn
	(message "XML-RPC is not available... not checking Syndic8.")
	nil)
    (require 'xml-rpc)
    (let ((feedid (xml-rpc-method-call
		   "http://www.syndic8.com/xmlrpc.php"
		   'syndic8.FindSites
		   url)))
      (when feedid
	(let* ((feedinfo (xml-rpc-method-call
			  "http://www.syndic8.com/xmlrpc.php"
			  'syndic8.GetFeedInfo
			  feedid))
	       (urllist
		(delq nil
		      (mapcar
		       (lambda (listinfo)
			 (if (string-equal
			      (cdr (assoc "status" listinfo))
			      "Syndicated")
			     (cons
			      (cdr (assoc "sitename" listinfo))
			      (list
			       (cons 'title
				     (cdr (assoc
					   "sitename" listinfo)))
			       (cons 'href
				     (cdr (assoc
					   "dataurl" listinfo)))))))
		       feedinfo))))
	  (if (not (> (length urllist) 1))
	      (cdar urllist)
	    (let ((completion-ignore-case t)
		  (selection
		   (mapcar (lambda (listinfo)
			     (cons (cdr (assoc "sitename" listinfo))
				   (string-to-number
				    (cdr (assoc "feedid" listinfo)))))
			   feedinfo)))
	      (cdr (assoc
		    (completing-read
		     "Multiple feeds found.  Select one: "
		     selection nil t) urllist)))))))))

(defun nnrss-rss-p (data)
  "Test if DATA is an RSS feed.
Simply ensures that the first element is rss or rdf."
  (or (eq (caar data) 'rss)
      (eq (caar data) 'rdf:RDF)))

(defun nnrss-rss-title-description (rss-namespace data url)
  "Return the title of an RSS feed."
  (if (nnrss-rss-p data)
      (let ((description (intern (concat rss-namespace "description")))
	    (title (intern (concat rss-namespace "title")))
	    (channel (nnrss-find-el (intern (concat rss-namespace "channel"))
				    data)))
	(list
	 (cons 'description (caddr (nth 0 (nnrss-find-el description channel))))
	 (cons 'title (caddr (nth 0 (nnrss-find-el title channel))))
	 (cons 'href url)))))

(defun nnrss-get-namespace-prefix (el uri)
  "Given EL (containing a parsed element) and URI (containing a string
that gives the URI for which you want to retrieve the namespace
prefix), return the prefix."
  (let* ((prefix (car (rassoc uri (cadar el))))
	 (nslist (if prefix
		     (split-string (symbol-name prefix) ":")))
	 (ns (cond ((eq (length nslist) 1) ; no prefix given
		    "")
		   ((eq (length nslist) 2) ; extract prefix
		    (cadr nslist)))))
    (if (and ns (not (string= ns "")))
	(concat ns ":")
      ns)))

(provide 'nnrss)


;;; nnrss.el ends here

;;; arch-tag: 12910c07-0cdf-44fb-8d2c-416ded64c267