unofficial mirror of emacs-devel@gnu.org 
 help / color / mirror / code / Atom feed
blob 10190f49339cb5a437553a5af0144c4c63ca09f6 57081 bytes (raw)
name: lisp/emacs-lisp/cl-generic.el 	 # note: path name is non-authoritative(*)

   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
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
 
;;; cl-generic.el --- CLOS-style generic functions for Elisp  -*- lexical-binding: t; -*-

;; Copyright (C) 2015-2019 Free Software Foundation, Inc.

;; Author: Stefan Monnier <monnier@iro.umontreal.ca>
;; Version: 1.0

;; 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 3 of the License, 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.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; This implements the most of CLOS's multiple-dispatch generic functions.
;; To use it you need either (require 'cl-generic) or (require 'cl-lib).
;; The main entry points are: `cl-defgeneric' and `cl-defmethod'.

;; Missing elements:
;; - We don't support make-method, call-method, define-method-combination.
;;   CLOS's define-method-combination is IMO overly complicated, and it suffers
;;   from a significant problem: the method-combination code returns a sexp
;;   that needs to be `eval'uated or compiled.  IOW it requires run-time
;;   code generation.  Given how rarely method-combinations are used,
;;   I just provided a cl-generic-combine-methods generic function, to which
;;   people can add methods if they are really desperate for such functionality.
;; - In defgeneric we don't support the options:
;;   declare, :method-combination, :generic-function-class, :method-class.
;; Added elements:
;; - We support aliases to generic functions.
;; - cl-generic-generalizers.  This generic function lets you extend the kind
;;   of thing on which to dispatch.  There is support in this file for
;;   dispatch on:
;;   - (eql <val>)
;;   - (head <val>) which checks that the arg is a cons with <val> as its head.
;;   - plain old types
;;   - type of CL structs
;;   eieio-core adds dispatch on:
;;   - class of eieio objects
;;   - actual class argument, using the syntax (subclass <class>).
;; - cl-generic-combine-methods (i.s.o define-method-combination and
;;   compute-effective-method).
;; - cl-generic-call-method (which replaces make-method and call-method).
;; - The standard method combination supports ":extra STRING" qualifiers
;;   which simply allows adding more methods for the same
;;   specializers&qualifiers.
;; - Methods can dispatch on the context.  For that, a method needs to specify
;;   context arguments, introduced by `&context' (which need to come right
;;   after the mandatory arguments and before anything like
;;   &optional/&rest/&key).  Each context argument is given as (EXP SPECIALIZER)
;;   which means that EXP is taken as an expression which computes some context
;;   and this value is then used to dispatch.
;;   E.g. (foo &context (major-mode (eql c-mode))) is an arglist specifying
;;   that this method will only be applicable when `major-mode' has value
;;   `c-mode'.

;; Efficiency considerations: overall, I've made an effort to make this fairly
;; efficient for the expected case (e.g. no constant redefinition of methods).
;; - Generic functions which do not dispatch on any argument are implemented
;;   optimally (just as efficient as plain old functions).
;; - Generic functions which only dispatch on one argument are fairly efficient
;;   (not a lot of room for improvement without changes to the byte-compiler,
;;   I think).
;; - Multiple dispatch is implemented rather naively.  There's an extra `apply'
;;   function call for every dispatch; we don't optimize each dispatch
;;   based on the set of candidate methods remaining; we don't optimize the
;;   order in which we performs the dispatches either;
;;   If/when this becomes a problem, we can try and optimize it.
;; - call-next-method could be made more efficient, but isn't too terrible.

;; TODO:
;;
;; - A generic "filter" generalizer (e.g. could be used to cleanly add methods
;;   to cl-generic-combine-methods with a specializer that says it applies only
;;   when some particular qualifier is used).

;;; Code:

;; The autoloads.el mechanism which adds package--builtin-versions
;; maintenance to loaddefs.el doesn't work for preloaded packages (such
;; as this one), so we have to do it by hand!
(push (purecopy '(cl-generic 1 0)) package--builtin-versions)

;; Note: For generic functions that dispatch on several arguments (i.e. those
;; which use the multiple-dispatch feature), we always use the same "tagcodes"
;; and the same set of arguments on which to dispatch.  This works, but is
;; often suboptimal since after one dispatch, the remaining dispatches can
;; usually be simplified, or even completely skipped.

(eval-when-compile (require 'cl-lib))
(eval-when-compile (require 'cl-macs))  ;For cl--find-class.
(eval-when-compile (require 'pcase))

(cl-defstruct (cl--generic-generalizer
               (:constructor nil)
               (:constructor cl-generic-make-generalizer
                (name priority tagcode-function specializers-function)))
  (name nil :type string)
  (priority nil :type integer)
  tagcode-function
  specializers-function)


(defmacro cl-generic-define-generalizer
    (name priority tagcode-function specializers-function)
  "Define a new kind of generalizer.
NAME is the name of the variable that will hold it.
PRIORITY defines which generalizer takes precedence.
  The catch-all generalizer has priority 0.
  Then `eql' generalizer has priority 100.
TAGCODE-FUNCTION takes as first argument a varname and should return
  a chunk of code that computes the tag of the value held in that variable.
  Further arguments are reserved for future use.
SPECIALIZERS-FUNCTION takes as first argument a tag value TAG
  and should return a list of specializers that match TAG.
  Further arguments are reserved for future use."
  (declare (indent 1) (debug (symbolp body)))
  `(defconst ,name
     (cl-generic-make-generalizer
      ',name ,priority ,tagcode-function ,specializers-function)))

(cl-generic-define-generalizer cl--generic-t-generalizer
   0 (lambda (_name &rest _) nil) (lambda (_tag &rest _) '(t)))

(cl-defstruct (cl--generic-method
               (:constructor nil)
               (:constructor cl--generic-make-method
                (specializers qualifiers uses-cnm function))
               (:predicate nil))
  (specializers nil :read-only t :type list)
  (qualifiers   nil :read-only t :type (list-of atom))
  ;; USES-CNM is a boolean indicating if FUNCTION expects an extra argument
  ;; holding the next-method.
  (uses-cnm     nil :read-only t :type boolean)
  (function     nil :read-only t :type function))

(cl-defstruct (cl--generic
               (:constructor nil)
               (:constructor cl--generic-make (name))
               (:predicate nil))
  (name nil :type symbol :read-only t)  ;Pointer back to the symbol.
  ;; `dispatches' holds a list of (ARGNUM . TAGCODES) where ARGNUM is the index
  ;; of the corresponding argument and TAGCODES is a list of (PRIORITY . EXP)
  ;; where the EXPs are expressions (to be `or'd together) to compute the tag
  ;; on which to dispatch and PRIORITY is the priority of each expression to
  ;; decide in which order to sort them.
  ;; The most important dispatch is last in the list (and the least is first).
  (dispatches nil :type (list-of (cons natnum (list-of generalizers))))
  (method-table nil :type (list-of cl--generic-method))
  (options nil :type list))

(defun cl-generic-function-options (generic)
  "Return the options of the generic function GENERIC."
  (cl--generic-options generic))

(defmacro cl--generic (name)
  `(get ,name 'cl--generic))

(defun cl-generic-p (f)
  "Return non-nil if F is a generic function."
  (and (symbolp f) (cl--generic f)))

(defun cl-generic-ensure-function (name &optional noerror)
  (let (generic
        (origname name))
    (while (and (null (setq generic (cl--generic name)))
                (fboundp name)
                (null noerror)
                (symbolp (symbol-function name)))
      (setq name (symbol-function name)))
    (unless (or (not (fboundp name))
                (autoloadp (symbol-function name))
                (and (functionp name) generic)
                noerror)
      (error "%s is already defined as something else than a generic function"
             origname))
    (if generic
        (cl-assert (eq name (cl--generic-name generic)))
      (setf (cl--generic name) (setq generic (cl--generic-make name))))
    generic))

;;;###autoload
(defmacro cl-defgeneric (name args &rest options-and-methods)
  "Create a generic function NAME.
DOC-STRING is the base documentation for this class.  A generic
function has no body, as its purpose is to decide which method body
is appropriate to use.  Specific methods are defined with `cl-defmethod'.
With this implementation the ARGS are currently ignored.
OPTIONS-AND-METHODS currently understands:
- (:documentation DOCSTRING)
- (declare DECLARATIONS)
- (:argument-precedence-order &rest ARGS)
- (:method [QUALIFIERS...] ARGS &rest BODY)
DEFAULT-BODY, if present, is used as the body of a default method.

\(fn NAME ARGS [DOC-STRING] [OPTIONS-AND-METHODS...] &rest DEFAULT-BODY)"
  (declare (indent 2) (doc-string 3)
           (debug
            (&define [&or name ("setf" name :name setf)] listp
                     lambda-doc
                     [&rest [&or
                             ("declare" &rest sexp)
                             (":argument-precedence-order" &rest sexp)
                             (&define ":method" [&rest atom]
                                      cl-generic-method-args lambda-doc
                                      def-body)]]
                     def-body)))
  (let* ((doc (if (stringp (car-safe options-and-methods))
                  (pop options-and-methods)))
         (declarations nil)
         (methods ())
         (options ())
         next-head)
    (while (progn (setq next-head (car-safe (car options-and-methods)))
                  (or (keywordp next-head)
                      (eq next-head 'declare)))
      (pcase next-head
        (`:documentation
         (when doc (error "Multiple doc strings for %S" name))
         (setq doc (cadr (pop options-and-methods))))
        (`declare
         (when declarations (error "Multiple `declare' for %S" name))
         (setq declarations (pop options-and-methods)))
        (`:method (push (cdr (pop options-and-methods)) methods))
        (_ (push (pop options-and-methods) options))))
    (when options-and-methods
      ;; Anything remaining is assumed to be a default method body.
      (push `(,args ,@options-and-methods) methods))
    (when (eq 'setf (car-safe name))
      (require 'gv)
      (declare-function gv-setter "gv" (name))
      (setq name (gv-setter (cadr name))))
    `(prog1
         (progn
           (defalias ',name
             (cl-generic-define ',name ',args ',(nreverse options))
             ,(help-add-fundoc-usage doc args))
           :autoload-end
           ,@(mapcar (lambda (method) `(cl-defmethod ,name ,@method))
                     (nreverse methods)))
       ,@(mapcar (lambda (declaration)
                   (let ((f (cdr (assq (car declaration)
                                       defun-declarations-alist))))
                     (cond
                      (f (apply (car f) name args (cdr declaration)))
                      (t (message "Warning: Unknown defun property `%S' in %S"
                                  (car declaration) name)
                         nil))))
                 (cdr declarations)))))

;;;###autoload
(defun cl-generic-define (name args options)
  (pcase-let* ((generic (cl-generic-ensure-function name 'noerror))
               (`(,spec-args . ,_) (cl--generic-split-args args))
               (mandatory (mapcar #'car spec-args))
               (apo (assq :argument-precedence-order options)))
    (unless (fboundp name)
      ;; If the generic function was fmakunbound, throw away previous methods.
      (setf (cl--generic-dispatches generic) nil)
      (setf (cl--generic-method-table generic) nil))
    (when apo
      (dolist (arg (cdr apo))
        (let ((pos (memq arg mandatory)))
          (unless pos (error "%S is not a mandatory argument" arg))
          (let* ((argno (- (length mandatory) (length pos)))
                 (dispatches (cl--generic-dispatches generic))
                 (dispatch (or (assq argno dispatches) (list argno))))
            (setf (cl--generic-dispatches generic)
                  (cons dispatch (delq dispatch dispatches)))))))
    (setf (cl--generic-options generic) options)
    (cl--generic-make-function generic)))

(defmacro cl-generic-current-method-specializers ()
  "List of (VAR . TYPE) where TYPE is var's specializer.
This macro can only be used within the lexical scope of a cl-generic method."
  (error "cl-generic-current-method-specializers used outside of a method"))

(defmacro cl-generic-define-context-rewriter (name args &rest body)
  "Define a special kind of context named NAME.
Whenever a context specializer of the form (NAME . ARGS) appears,
the specializer used will be the one returned by BODY."
  (declare (debug (&define name lambda-list def-body)) (indent defun))
  `(eval-and-compile
     (put ',name 'cl-generic--context-rewriter
          (lambda ,args ,@body))))

(eval-and-compile         ;Needed while compiling the cl-defmethod calls below!
  (defun cl--generic-fgrep (vars sexp)    ;Copied from pcase.el.
    "Check which of the symbols VARS appear in SEXP."
    (let ((res '()))
      (while (consp sexp)
        (dolist (var (cl--generic-fgrep vars (pop sexp)))
          (unless (memq var res) (push var res))))
      (and (memq sexp vars) (not (memq sexp res)) (push sexp res))
      res))

  (defun cl--generic-split-args (args)
    "Return (SPEC-ARGS . PLAIN-ARGS)."
    (let ((plain-args ())
          (specializers nil)
          (mandatory t))
      (dolist (arg args)
        (push (pcase arg
                ((or '&optional '&rest '&key) (setq mandatory nil) arg)
                ('&context
                 (unless mandatory
                   (error "&context not immediately after mandatory args"))
                 (setq mandatory 'context) nil)
                ((let 'nil mandatory) arg)
                ((let 'context mandatory)
                 (unless (consp arg)
                   (error "Invalid &context arg: %S" arg))
                 (let* ((name (car arg))
                        (rewriter
                         (and (symbolp name)
                              (get name 'cl-generic--context-rewriter))))
                   (if rewriter (setq arg (apply rewriter (cdr arg)))))
                 (push `((&context . ,(car arg)) . ,(cadr arg)) specializers)
                 nil)
                (`(,name . ,type)
                 (push (cons name (car type)) specializers)
                 name)
                (_
                 (push (cons arg t) specializers)
                 arg))
              plain-args))
      (cons (nreverse specializers)
            (nreverse (delq nil plain-args)))))

  (defun cl--generic-lambda (args body)
    "Make the lambda expression for a method with ARGS and BODY."
    (pcase-let* ((`(,spec-args . ,plain-args)
                  (cl--generic-split-args args))
                 (fun `(cl-function (lambda ,plain-args ,@body)))
                 (macroenv (cons `(cl-generic-current-method-specializers
                                   . ,(lambda () spec-args))
                                 macroexpand-all-environment)))
      (require 'cl-lib)        ;Needed to expand `cl-flet' and `cl-function'.
      (when (interactive-form (cadr fun))
        (message "Interactive forms unsupported in generic functions: %S"
                 (interactive-form (cadr fun))))
      ;; First macroexpand away the cl-function stuff (e.g. &key and
      ;; destructuring args, `declare' and whatnot).
      (pcase (macroexpand fun macroenv)
        (`#'(lambda ,args . ,body)
         (let* ((parsed-body (macroexp-parse-body body))
                (cnm (make-symbol "cl--cnm"))
                (nmp (make-symbol "cl--nmp"))
                (nbody (macroexpand-all
                        `(cl-flet ((cl-call-next-method ,cnm)
                                   (cl-next-method-p ,nmp))
                           ,@(cdr parsed-body))
                        macroenv))
                ;; FIXME: Rather than `grep' after the fact, the
                ;; macroexpansion should directly set some flag when cnm
                ;; is used.
                ;; FIXME: Also, optimize the case where call-next-method is
                ;; only called with explicit arguments.
                (uses-cnm (cl--generic-fgrep (list cnm nmp) nbody)))
           (cons (not (not uses-cnm))
                 `#'(lambda (,@(if uses-cnm (list cnm)) ,@args)
                      ,@(car parsed-body)
                      ,(if (not (memq nmp uses-cnm))
                           nbody
                         `(let ((,nmp (lambda ()
                                        (cl--generic-isnot-nnm-p ,cnm))))
                            ,nbody))))))
        (f (error "Unexpected macroexpansion result: %S" f))))))

(put 'cl-defmethod 'function-documentation
     '(cl--generic-make-defmethod-docstring))

(defun cl--generic-make-defmethod-docstring ()
  ;; FIXME: Copy&paste from pcase--make-docstring.
  (let* ((main (documentation (symbol-function 'cl-defmethod) 'raw))
         (ud (help-split-fundoc main 'cl-defmethod)))
    ;; So that eg emacs -Q -l cl-lib --eval "(documentation 'pcase)" works,
    ;; where cl-lib is anything using pcase-defmacro.
    (require 'help-fns)
    (with-temp-buffer
      (insert (or (cdr ud) main))
      (insert "\n\n\tCurrently supported forms for TYPE:\n\n")
      (dolist (method (reverse (cl--generic-method-table
                                (cl--generic 'cl-generic-generalizers))))
        (let* ((info (cl--generic-method-info method)))
          (when (nth 2 info)
          (insert (nth 2 info) "\n\n"))))
      (let ((combined-doc (buffer-string)))
        (if ud (help-add-fundoc-usage combined-doc (car ud)) combined-doc)))))

;;;###autoload
(defmacro cl-defmethod (name args &rest body)
  "Define a new method for generic function NAME.
I.e. it defines the implementation of NAME to use for invocations where the
values of the dispatch arguments match the specified TYPEs.
The dispatch arguments have to be among the mandatory arguments, and
all methods of NAME have to use the same set of arguments for dispatch.
Each dispatch argument and TYPE are specified in ARGS where the corresponding
formal argument appears as (VAR TYPE) rather than just VAR.

The optional second argument QUALIFIER is a specifier that
modifies how the method is combined with other methods, including:
   :before  - Method will be called before the primary
   :after   - Method will be called after the primary
   :around  - Method will be called around everything else
The absence of QUALIFIER means this is a \"primary\" method.
The set of acceptable qualifiers and their meaning is defined
\(and can be extended) by the methods of `cl-generic-combine-methods'.

ARGS can also include so-called context specializers, introduced by
`&context' (which should appear right after the mandatory arguments,
before any &optional or &rest).  They have the form (EXPR TYPE) where
EXPR is an Elisp expression whose value should match TYPE for the
method to be applicable.

The set of acceptable TYPEs (also called \"specializers\") is defined
\(and can be extended) by the various methods of `cl-generic-generalizers'.

\(fn NAME [QUALIFIER] ARGS &rest [DOCSTRING] BODY)"
  (declare (doc-string 3) (indent defun)
           (debug
            (&define                    ; this means we are defining something
             [&or name ("setf" name :name setf)]
             ;; ^^ This is the methods symbol
             [ &rest atom ]         ; Multiple qualifiers are allowed.
                                    ; Like in CLOS spec, we support
                                    ; any non-list values.
             cl-generic-method-args     ; arguments
             lambda-doc                 ; documentation string
             def-body)))                ; part to be debugged
  (let ((qualifiers nil))
    (while (not (listp args))
      (push args qualifiers)
      (setq args (pop body)))
    (when (eq 'setf (car-safe name))
      (require 'gv)
      (declare-function gv-setter "gv" (name))
      (setq name (gv-setter (cadr name))))
    (pcase-let* ((`(,uses-cnm . ,fun) (cl--generic-lambda args body)))
      `(progn
         ,(and (get name 'byte-obsolete-info)
               (or (not (fboundp 'byte-compile-warning-enabled-p))
                   (byte-compile-warning-enabled-p 'obsolete name))
               (let* ((obsolete (get name 'byte-obsolete-info)))
                 (macroexp--warn-and-return
                  (macroexp--obsolete-warning name obsolete "generic function")
                  nil)))
         ;; You could argue that `defmethod' modifies rather than defines the
         ;; function, so warnings like "not known to be defined" are fair game.
         ;; But in practice, it's common to use `cl-defmethod'
         ;; without a previous `cl-defgeneric'.
         ;; The ",'" is a no-op that pacifies check-declare.
         (,'declare-function ,name "")
         (cl-generic-define-method ',name ',(nreverse qualifiers) ',args
                                   ,uses-cnm ,fun)))))

(defun cl--generic-member-method (specializers qualifiers methods)
  (while
      (and methods
           (let ((m (car methods)))
             (not (and (equal (cl--generic-method-specializers m) specializers)
                       (equal (cl--generic-method-qualifiers m) qualifiers)))))
    (setq methods (cdr methods)))
  methods)

(defun cl--generic-load-hist-format (name qualifiers specializers)
  ;; FIXME: This function is used in elisp-mode.el and
  ;; elisp-mode-tests.el, but I still decided to use an internal name
  ;; because these uses should be removed or moved into cl-generic.el.
  `(,name ,qualifiers . ,specializers))

;;;###autoload
(defun cl-generic-define-method (name qualifiers args uses-cnm function)
  (pcase-let*
      ((generic (cl-generic-ensure-function name))
       (`(,spec-args . ,_) (cl--generic-split-args args))
       (specializers (mapcar (lambda (spec-arg)
                               (if (eq '&context (car-safe (car spec-arg)))
                                   spec-arg (cdr spec-arg)))
                             spec-args))
       (method (cl--generic-make-method
                specializers qualifiers uses-cnm function))
       (mt (cl--generic-method-table generic))
       (me (cl--generic-member-method specializers qualifiers mt))
       (dispatches (cl--generic-dispatches generic))
       (i 0))
    (dolist (spec-arg spec-args)
      (let* ((key (if (eq '&context (car-safe (car spec-arg)))
                      (car spec-arg) i))
             (generalizers (cl-generic-generalizers (cdr spec-arg)))
             (x (assoc key dispatches)))
        (unless x
          (setq x (cons key (cl-generic-generalizers t)))
          (setf (cl--generic-dispatches generic)
                (setq dispatches (cons x dispatches))))
        (dolist (generalizer generalizers)
          (unless (member generalizer (cdr x))
            (setf (cdr x)
                  (sort (cons generalizer (cdr x))
                        (lambda (x y)
                          (> (cl--generic-generalizer-priority x)
                             (cl--generic-generalizer-priority y)))))))
        (setq i (1+ i))))
    ;; We used to (setcar me method), but that can cause false positives in
    ;; the hash-consing table of the method-builder (bug#20644).
    ;; See also the related FIXME in cl--generic-build-combined-method.
    (setf (cl--generic-method-table generic)
          (if (null me)
              (cons method mt)
            ;; Keep the ordering; important for methods with :extra qualifiers.
            (mapcar (lambda (x) (if (eq x (car me)) method x)) mt)))
    (let ((sym (cl--generic-name generic))) ; Actual name (for aliases).
      (unless (symbol-function sym)
        (defalias sym 'dummy))   ;Record definition into load-history.
      (cl-pushnew `(cl-defmethod . ,(cl--generic-load-hist-format
                                     (cl--generic-name generic)
                                     qualifiers specializers))
                  current-load-list :test #'equal)
      ;; FIXME: Try to avoid re-constructing a new function if the old one
      ;; is still valid (e.g. still empty method cache)?
      (let ((gfun (cl--generic-make-function generic))
            ;; Prevent `defalias' from recording this as the definition site of
            ;; the generic function.
            current-load-list
            ;; BEWARE!  Don't purify this function definition, since that leads
            ;; to memory corruption if the hash-tables it holds are modified
            ;; (the GC doesn't trace those pointers).
            (purify-flag nil))
        ;; But do use `defalias', so that it interacts properly with nadvice,
        ;; e.g. for tracing/debug-on-entry.
        (defalias sym gfun)))))

(defmacro cl--generic-with-memoization (place &rest code)
  (declare (indent 1) (debug t))
  (gv-letplace (getter setter) place
    `(or ,getter
         ,(macroexp-let2 nil val (macroexp-progn code)
            `(progn
               ,(funcall setter val)
               ,val)))))

(defvar cl--generic-dispatchers (make-hash-table :test #'equal))

(defun cl--generic-get-dispatcher (dispatch)
  (cl--generic-with-memoization
      (gethash dispatch cl--generic-dispatchers)
    ;; (message "cl--generic-get-dispatcher (%S)" dispatch)
    (let* ((dispatch-arg (car dispatch))
           (generalizers (cdr dispatch))
           (lexical-binding t)
           (tagcodes
            (mapcar (lambda (generalizer)
                      (funcall (cl--generic-generalizer-tagcode-function
                                generalizer)
                               'arg))
                    generalizers))
           (typescodes
            (mapcar
             (lambda (generalizer)
               `(funcall ',(cl--generic-generalizer-specializers-function
                            generalizer)
                         ,(funcall (cl--generic-generalizer-tagcode-function
                                    generalizer)
                                   'arg)))
             generalizers))
           (tag-exp
            ;; Minor optimization: since this tag-exp is
            ;; only used to lookup the method-cache, it
            ;; doesn't matter if the default value is some
            ;; constant or nil.
            `(or ,@(if (macroexp-const-p (car (last tagcodes)))
                       (butlast tagcodes)
                     tagcodes)))
           (fixedargs '(arg))
           (dispatch-idx dispatch-arg)
           (bindings nil))
      (when (eq '&context (car-safe dispatch-arg))
        (setq bindings `((arg ,(cdr dispatch-arg))))
        (setq fixedargs nil)
        (setq dispatch-idx 0))
      (dotimes (i dispatch-idx)
        (push (make-symbol (format "arg%d" (- dispatch-idx i 1))) fixedargs))
      ;; FIXME: For generic functions with a single method (or with 2 methods,
      ;; one of which always matches), using a tagcode + hash-table is
      ;; overkill: better just use a `cl-typep' test.
      (byte-compile
       `(lambda (generic dispatches-left methods)
          (let ((method-cache (make-hash-table :test #'eql)))
            (lambda (,@fixedargs &rest args)
              (let ,bindings
                (apply (cl--generic-with-memoization
                        (gethash ,tag-exp method-cache)
                        (cl--generic-cache-miss
                         generic ',dispatch-arg dispatches-left methods
                         ,(if (cdr typescodes)
                              `(append ,@typescodes) (car typescodes))))
                       ,@fixedargs args)))))))))

(defun cl--generic-make-function (generic)
  (cl--generic-make-next-function generic
                                  (cl--generic-dispatches generic)
                                  (cl--generic-method-table generic)))

(defun cl--generic-make-next-function (generic dispatches methods)
  (let* ((dispatch
          (progn
            (while (and dispatches
                        (let ((x (nth 1 (car dispatches))))
                          ;; No need to dispatch for t specializers.
                          (or (null x) (equal x cl--generic-t-generalizer))))
              (setq dispatches (cdr dispatches)))
            (pop dispatches))))
    (if (not (and dispatch
                  ;; If there's no method left, there's no point checking
                  ;; further arguments.
                  methods))
        (cl--generic-build-combined-method generic methods)
      (let ((dispatcher (cl--generic-get-dispatcher dispatch)))
        (funcall dispatcher generic dispatches methods)))))

(defvar cl--generic-combined-method-memoization
  (make-hash-table :test #'equal :weakness 'value)
  "Table storing previously built combined-methods.
This is particularly useful when many different tags select the same set
of methods, since this table then allows us to share a single combined-method
for all those different tags in the method-cache.")

(define-error 'cl--generic-cyclic-definition "Cyclic definition: %S")

(defun cl--generic-build-combined-method (generic methods)
  (if (null methods)
      ;; Special case needed to fix a circularity during bootstrap.
      (cl--generic-standard-method-combination generic methods)
    (let ((f
           (cl--generic-with-memoization
               ;; FIXME: Since the fields of `generic' are modified, this
               ;; hash-table won't work right, because the hashes will change!
               ;; It's not terribly serious, but reduces the effectiveness of
               ;; the table.
               (gethash (cons generic methods)
                        cl--generic-combined-method-memoization)
             (puthash (cons generic methods) :cl--generic--under-construction
                      cl--generic-combined-method-memoization)
             (condition-case nil
                 (cl-generic-combine-methods generic methods)
               ;; Special case needed to fix a circularity during bootstrap.
               (cl--generic-cyclic-definition
                (cl--generic-standard-method-combination generic methods))))))
      (if (eq f :cl--generic--under-construction)
          (signal 'cl--generic-cyclic-definition
                  (list (cl--generic-name generic)))
        f))))

(defun cl--generic-no-next-method-function (generic method)
  (lambda (&rest args)
    (apply #'cl-no-next-method generic method args)))

(defun cl-generic-call-method (generic method &optional fun)
  "Return a function that calls METHOD.
FUN is the function that should be called when METHOD calls
`call-next-method'."
  (if (not (cl--generic-method-uses-cnm method))
      (cl--generic-method-function method)
    (let ((met-fun (cl--generic-method-function method))
          (next (or fun (cl--generic-no-next-method-function
                         generic method))))
      (lambda (&rest args)
        (apply met-fun
               ;; FIXME: This sucks: passing just `next' would
               ;; be a lot more efficient than the lambda+apply
               ;; quasi-η, but we need this to implement the
               ;; "if call-next-method is called with no
               ;; arguments, then use the previous arguments".
               (lambda (&rest cnm-args)
                 (apply next (or cnm-args args)))
               args)))))

;; Standard CLOS name.
(defalias 'cl-method-qualifiers #'cl--generic-method-qualifiers)

(defun cl--generic-standard-method-combination (generic methods)
  (let ((mets-by-qual ()))
    (dolist (method methods)
      (let ((qualifiers (cl-method-qualifiers method)))
        (if (eq (car qualifiers) :extra) (setq qualifiers (cddr qualifiers)))
        (unless (member qualifiers '(() (:after) (:before) (:around)))
          (error "Unsupported qualifiers in function %S: %S"
                 (cl--generic-name generic) qualifiers))
        (push method (alist-get (car qualifiers) mets-by-qual))))
    (cond
     ((null mets-by-qual)
      (lambda (&rest args)
        (apply #'cl-no-applicable-method generic args)))
     ((null (alist-get nil mets-by-qual))
      (lambda (&rest args)
        (apply #'cl-no-primary-method generic args)))
     (t
      (let* ((fun nil)
             (ab-call (lambda (m) (cl-generic-call-method generic m)))
             (before
              (mapcar ab-call (reverse (cdr (assoc :before mets-by-qual)))))
             (after (mapcar ab-call (cdr (assoc :after mets-by-qual)))))
        (dolist (method (cdr (assoc nil mets-by-qual)))
          (setq fun (cl-generic-call-method generic method fun)))
        (when (or after before)
          (let ((next fun))
            (setq fun (lambda (&rest args)
                        (dolist (bf before)
                          (apply bf args))
                        (prog1
                            (apply next args)
                          (dolist (af after)
                            (apply af args)))))))
        (dolist (method (cdr (assoc :around mets-by-qual)))
          (setq fun (cl-generic-call-method generic method fun)))
        fun)))))

(defun cl-generic-apply (generic args)
  "Like `apply' but takes a cl-generic object rather than a function."
  ;; Handy in cl-no-applicable-method, for example.
  ;; In Common Lisp, generic-function objects are funcallable.  Ideally
  ;; we'd want the same in Elisp, but it would either require using a very
  ;; different (and less efficient) representation of cl--generic objects,
  ;; or non-trivial changes in the general infrastructure (compiler and such).
  (apply (cl--generic-name generic) args))

(defun cl--generic-arg-specializer (method dispatch-arg)
  (or (if (integerp dispatch-arg)
          (nth dispatch-arg
               (cl--generic-method-specializers method))
        (cdr (assoc dispatch-arg
                    (cl--generic-method-specializers method))))
      t))

(defun cl--generic-cache-miss (generic
                               dispatch-arg dispatches-left methods-left types)
  (let ((methods '()))
    (dolist (method methods-left)
      (let* ((specializer (cl--generic-arg-specializer method dispatch-arg))
             (m (member specializer types)))
        (when m
          (push (cons (length m) method) methods))))
    ;; Sort the methods, most specific first.
    ;; It would be tempting to sort them once and for all in the method-table
    ;; rather than here, but the order might depend on the actual argument
    ;; (e.g. for multiple inheritance with defclass).
    (setq methods (nreverse (mapcar #'cdr (sort methods #'car-less-than-car))))
    (cl--generic-make-next-function generic dispatches-left methods)))

(cl-defgeneric cl-generic-generalizers (specializer)
  "Return a list of generalizers for a given SPECIALIZER.
To each kind of `specializer', corresponds a `generalizer' which describes
how to extract a \"tag\" from an object which will then let us check if this
object matches the specializer.  A typical example of a \"tag\" would be the
type of an object.  It's called a `generalizer' because it
takes a specific object and returns a more general approximation,
denoting a set of objects to which it belongs.
A generalizer gives us the chunk of code which the
dispatch function needs to use to extract the \"tag\" of an object, as well
as a function which turns this tag into an ordered list of
`specializers' that this object matches.
The code which extracts the tag should be as fast as possible.
The tags should be chosen according to the following rules:
- The tags should not be too specific: similar objects which match the
  same list of specializers should ideally use the same (`eql') tag.
  This insures that the cached computation of the applicable
  methods for one object can be reused for other objects.
- Corollary: objects which don't match any of the relevant specializers
  should ideally all use the same tag (typically nil).
  This insures that this cache does not grow unnecessarily large.
- Two different generalizers G1 and G2 should not use the same tag
  unless they use it for the same set of objects.  IOW, if G1.tag(X1) =
  G2.tag(X2) then G1.tag(X1) = G2.tag(X1) = G1.tag(X2) = G2.tag(X2).
- If G1.priority > G2.priority and G1.tag(X1) = G1.tag(X2) and this tag is
  non-nil, then you have to make sure that the G2.tag(X1) = G2.tag(X2).
  This is because the method-cache is only indexed with the first non-nil
  tag (by order of decreasing priority).")

(cl-defgeneric cl-generic-combine-methods (generic methods)
  "Build the effective method made of METHODS.
It should return a function that expects the same arguments as the methods, and
 calls those methods in some appropriate order.
GENERIC is the generic function (mostly used for its name).
METHODS is the list of the selected methods.
The METHODS list is sorted from most specific first to most generic last.
The function can use `cl-generic-call-method' to create functions that call those
methods.")

(unless (ignore-errors (cl-generic-generalizers t))
  ;; Temporary definition to let the next defmethod succeed.
  (fset 'cl-generic-generalizers
        (lambda (specializer)
          (if (eq t specializer) (list cl--generic-t-generalizer))))
  (fset 'cl-generic-combine-methods #'cl--generic-standard-method-combination))

(cl-defmethod cl-generic-generalizers (specializer)
  "Support for the catch-all t specializer which always matches."
  (if (eq specializer t) (list cl--generic-t-generalizer)
    (error "Unknown specializer %S" specializer)))

(eval-when-compile
  ;; This macro is brittle and only really important in order to be
  ;; able to preload cl-generic without also preloading the byte-compiler,
  ;; So we use `eval-when-compile' so as not keep it available longer than
  ;; strictly needed.
(defmacro cl--generic-prefill-dispatchers (arg-or-context &rest specializers)
  (unless (integerp arg-or-context)
    (setq arg-or-context `(&context . ,arg-or-context)))
  (unless (fboundp 'cl--generic-get-dispatcher)
    (require 'cl-generic))
  (let ((fun (cl--generic-get-dispatcher
              `(,arg-or-context
                ,@(apply #'append
                         (mapcar #'cl-generic-generalizers specializers))
                ,cl--generic-t-generalizer))))
    ;; Recompute dispatch at run-time, since the generalizers may be slightly
    ;; different (e.g. byte-compiled rather than interpreted).
    ;; FIXME: There is a risk that the run-time generalizer is not equivalent
    ;; to the compile-time one, in which case `fun' may not be correct
    ;; any more!
    `(let ((dispatch
            `(,',arg-or-context
              ,@(apply #'append
                       (mapcar #'cl-generic-generalizers ',specializers))
              ,cl--generic-t-generalizer)))
       ;; (message "Prefilling for %S with \n%S" dispatch ',fun)
       (puthash dispatch ',fun cl--generic-dispatchers)))))

(cl-defmethod cl-generic-combine-methods (generic methods)
  "Standard support for :after, :before, :around, and `:extra NAME' qualifiers."
  (cl--generic-standard-method-combination generic methods))

(defconst cl--generic-nnm-sample (cl--generic-no-next-method-function t t))
(defconst cl--generic-cnm-sample
  (funcall (cl--generic-build-combined-method
            nil (list (cl--generic-make-method () () t #'identity)))))

(defun cl--generic-isnot-nnm-p (cnm)
  "Return non-nil if CNM is the function that calls `cl-no-next-method'."
  ;; ¡Big Gross Ugly Hack!
  ;; `next-method-p' just sucks, we should let it die.  But EIEIO did support
  ;; it, and some packages use it, so we need to support it.
  (catch 'found
    (cl-assert (function-equal cnm cl--generic-cnm-sample))
    (if (byte-code-function-p cnm)
        (let ((cnm-constants (aref cnm 2))
              (sample-constants (aref cl--generic-cnm-sample 2)))
          (dotimes (i (length sample-constants))
            (when (function-equal (aref sample-constants i)
                                  cl--generic-nnm-sample)
              (throw 'found
                     (not (function-equal (aref cnm-constants i)
                                          cl--generic-nnm-sample))))))
      (cl-assert (eq 'closure (car-safe cl--generic-cnm-sample)))
      (let ((cnm-env (cadr cnm)))
        (dolist (vb (cadr cl--generic-cnm-sample))
          (when (function-equal (cdr vb) cl--generic-nnm-sample)
            (throw 'found
                   (not (function-equal (cdar cnm-env)
                                        cl--generic-nnm-sample))))
          (setq cnm-env (cdr cnm-env)))))
    (error "Haven't found no-next-method-sample in cnm-sample")))

;;; Define some pre-defined generic functions, used internally.

(define-error 'cl-no-method "No method")
(define-error 'cl-no-next-method "No next method" 'cl-no-method)
(define-error 'cl-no-primary-method "No primary method" 'cl-no-method)
(define-error 'cl-no-applicable-method "No applicable method"
  'cl-no-method)

(cl-defgeneric cl-no-next-method (generic method &rest args)
  "Function called when `cl-call-next-method' finds no next method."
  (signal 'cl-no-next-method `(,(cl--generic-name generic) ,method ,@args)))

(cl-defgeneric cl-no-applicable-method (generic &rest args)
  "Function called when a method call finds no applicable method."
  (signal 'cl-no-applicable-method `(,(cl--generic-name generic) ,@args)))

(cl-defgeneric cl-no-primary-method (generic &rest args)
  "Function called when a method call finds no primary method."
  (signal 'cl-no-primary-method `(,(cl--generic-name generic) ,@args)))

(defun cl-call-next-method (&rest _args)
  "Function to call the next applicable method.
Can only be used from within the lexical body of a primary or around method."
  (error "cl-call-next-method only allowed inside primary and around methods"))

(defun cl-next-method-p ()
  "Return non-nil if there is a next method.
Can only be used from within the lexical body of a primary or around method."
  (declare (obsolete "make sure there's always a next method, or catch `cl-no-next-method' instead" "25.1"))
  (error "cl-next-method-p only allowed inside primary and around methods"))

;;;###autoload
(defun cl-find-method (generic qualifiers specializers)
  (car (cl--generic-member-method
        specializers qualifiers
        (cl--generic-method-table (cl--generic generic)))))

;;; Add support for describe-function

(defun cl--generic-search-method (met-name)
  "For `find-function-regexp-alist'. Searches for a cl-defmethod.
MET-NAME is as returned by `cl--generic-load-hist-format'."
  (let ((base-re (concat "(\\(?:cl-\\)?defmethod[ \t]+"
                         (regexp-quote (format "%s" (car met-name)))
			 "\\_>")))
    (or
     (re-search-forward
      (concat base-re "[^&\"\n]*"
              (mapconcat (lambda (qualifier)
                           (regexp-quote (format "%S" qualifier)))
                         (cadr met-name)
                         "[ \t\n]*")
              (mapconcat (lambda (specializer)
                           (regexp-quote
                            (format "%S" (if (consp specializer)
                                             (nth 1 specializer) specializer))))
                         (remq t (cddr met-name))
                         "[ \t\n]*)[^&\"\n]*"))
      nil t)
     (re-search-forward base-re nil t))))

;; WORKAROUND: This can't be a defconst due to bug#21237.
(defvar cl--generic-find-defgeneric-regexp "(\\(?:cl-\\)?defgeneric[ \t]+%s\\>")

(with-eval-after-load 'find-func
  (defvar find-function-regexp-alist)
  (add-to-list 'find-function-regexp-alist
               `(cl-defmethod . ,#'cl--generic-search-method))
  (add-to-list 'find-function-regexp-alist
               '(cl-defgeneric . cl--generic-find-defgeneric-regexp)))

(defun cl--generic-method-info (method)
  (let* ((specializers (cl--generic-method-specializers method))
         (qualifiers   (cl--generic-method-qualifiers method))
         (uses-cnm     (cl--generic-method-uses-cnm method))
         (function     (cl--generic-method-function method))
         (args (help-function-arglist function 'names))
         (docstring (documentation function))
         (qual-string
          (if (null qualifiers) ""
            (cl-assert (consp qualifiers))
            (let ((s (prin1-to-string qualifiers)))
              (concat (substring s 1 -1) " "))))
         (doconly (if docstring
                      (let ((split (help-split-fundoc docstring nil)))
                        (if split (cdr split) docstring))))
         (combined-args ()))
    (if uses-cnm (setq args (cdr args)))
    (dolist (specializer specializers)
      (let ((arg (if (eq '&rest (car args))
                     (intern (format "arg%d" (length combined-args)))
                   (pop args))))
        (push (if (eq specializer t) arg (list arg specializer))
              combined-args)))
    (setq combined-args (append (nreverse combined-args) args))
    (list qual-string combined-args doconly)))

(add-hook 'help-fns-describe-function-functions #'cl--generic-describe)
(defun cl--generic-describe (function)
  ;; Supposedly this is called from help-fns, so help-fns should be loaded at
  ;; this point.
  (declare-function help-fns-short-filename "help-fns" (filename))
  (let ((generic (if (symbolp function) (cl--generic function))))
    (when generic
      (require 'help-mode)              ;Needed for `help-function-def' button!
      (save-excursion
        (insert "\n\nThis is a generic function.\n\n")
        (insert (propertize "Implementations:\n\n" 'face 'bold))
        ;; Loop over fanciful generics
        (dolist (method (cl--generic-method-table generic))
          (let* ((info (cl--generic-method-info method)))
            ;; FIXME: Add hyperlinks for the types as well.
            (insert (format "%s%S" (nth 0 info) (nth 1 info)))
            (let* ((met-name (cl--generic-load-hist-format
                              function
                              (cl--generic-method-qualifiers method)
                              (cl--generic-method-specializers method)))
                   (file (find-lisp-object-file-name met-name 'cl-defmethod)))
              (when file
                (insert (substitute-command-keys " in `"))
                (help-insert-xref-button (help-fns-short-filename file)
                                         'help-function-def met-name file
                                         'cl-defmethod)
                (insert (substitute-command-keys "'.\n"))))
            (insert "\n" (or (nth 2 info) "Undocumented") "\n\n")))))))

(defun cl--generic-specializers-apply-to-type-p (specializers type)
  "Return non-nil if a method with SPECIALIZERS applies to TYPE."
  (let ((applies nil))
    (dolist (specializer specializers)
      (if (memq (car-safe specializer) '(subclass eieio--static))
          (setq specializer (nth 1 specializer)))
      ;; Don't include the methods that are "too generic", such as those
      ;; applying to `eieio-default-superclass'.
      (and (not (memq specializer '(t eieio-default-superclass)))
           (or (equal type specializer)
               (when (symbolp specializer)
                 (let ((sclass (cl--find-class specializer))
                       (tclass (cl--find-class type)))
                   (when (and sclass tclass)
                     (member specializer (cl--generic-class-parents tclass))))))
           (setq applies t)))
    applies))

(defun cl-generic-all-functions (&optional type)
  "Return a list of all generic functions.
Optional TYPE argument returns only those functions that contain
methods for TYPE."
  (let ((l nil))
    (mapatoms
     (lambda (symbol)
       (let ((generic (and (fboundp symbol) (cl--generic symbol))))
         (and generic
	      (catch 'found
		(if (null type) (throw 'found t))
		(dolist (method (cl--generic-method-table generic))
		  (if (cl--generic-specializers-apply-to-type-p
		       (cl--generic-method-specializers method) type)
		      (throw 'found t))))
	      (push symbol l)))))
    l))

(defun cl--generic-method-documentation (function type)
  "Return info for all methods of FUNCTION (a symbol) applicable to TYPE.
The value returned is a list of elements of the form
\(QUALIFIERS ARGS DOC)."
  (let ((generic (cl--generic function))
        (docs ()))
    (when generic
      (dolist (method (cl--generic-method-table generic))
        (when (cl--generic-specializers-apply-to-type-p
               (cl--generic-method-specializers method) type)
          (push (cl--generic-method-info method) docs))))
    docs))

(defun cl--generic-method-files (method)
  "Return a list of files where METHOD is defined by `cl-defmethod'.
The list will have entries of the form (FILE . (METHOD ...))
where (METHOD ...) contains the qualifiers and specializers of
the method and is a suitable argument for
`find-function-search-for-symbol'.  Filenames are absolute."
  (let (result)
    (pcase-dolist (`(,file . ,defs) load-history)
      (dolist (def defs)
        (when (and (eq (car-safe def) 'cl-defmethod)
                   (eq (cadr def) method))
          (push (cons file (cdr def)) result))))
    result))

;;; Support for (head <val>) specializers.

;; For both the `eql' and the `head' specializers, the dispatch
;; is unsatisfactory.  Basically, in the "common&fast case", we end up doing
;;
;;    (let ((tag (gethash value <tagcode-hashtable>)))
;;      (funcall (gethash tag <method-cache>)))
;;
;; whereas we'd like to just do
;;
;;      (funcall (gethash value <method-cache>)))
;;
;; but the problem is that the method-cache is normally "open ended", so
;; a nil means "not computed yet" and if we bump into it, we dutifully fill the
;; corresponding entry, whereas we'd want to just fallback on some default
;; effective method (so as not to fill the cache with lots of redundant
;; entries).

(defvar cl--generic-head-used (make-hash-table :test #'eql))

(cl-generic-define-generalizer cl--generic-head-generalizer
  80 (lambda (name &rest _) `(gethash (car-safe ,name) cl--generic-head-used))
  (lambda (tag &rest _) (if (eq (car-safe tag) 'head) (list tag))))

(cl-defmethod cl-generic-generalizers :extra "head" (specializer)
  "Support for (head VAL) specializers.
These match if the argument is a cons cell whose car is `eql' to VAL."
  ;; We have to implement `head' here using the :extra qualifier,
  ;; since we can't use the `head' specializer to implement itself.
  (if (not (eq (car-safe specializer) 'head))
      (cl-call-next-method)
    (cl--generic-with-memoization
        (gethash (cadr specializer) cl--generic-head-used) specializer)
    (list cl--generic-head-generalizer)))

(cl--generic-prefill-dispatchers 0 (head eql))

;;; Support for (eql <val>) specializers.

(defvar cl--generic-eql-used (make-hash-table :test #'eql))

(cl-generic-define-generalizer cl--generic-eql-generalizer
  100 (lambda (name &rest _) `(gethash ,name cl--generic-eql-used))
  (lambda (tag &rest _) (if (eq (car-safe tag) 'eql) (list tag))))

(cl-defmethod cl-generic-generalizers ((specializer (head eql)))
  "Support for (eql VAL) specializers.
These match if the argument is `eql' to VAL."
  (puthash (cadr specializer) specializer cl--generic-eql-used)
  (list cl--generic-eql-generalizer))

(cl--generic-prefill-dispatchers 0 (eql nil))
(cl--generic-prefill-dispatchers window-system (eql nil))
(cl--generic-prefill-dispatchers (terminal-parameter nil 'xterm--get-selection)
                                 (eql nil))
(cl--generic-prefill-dispatchers (terminal-parameter nil 'xterm--set-selection)
                                 (eql nil))

;;; Support for cl-defstructs specializers.

(defun cl--generic-struct-tag (name &rest _)
  ;; Use exactly the same code as for `typeof'.
  `(if ,name (type-of ,name) 'null))

(defun cl--generic-class-parents (class)
  (let ((parents ())
        (classes (list class)))
    ;; BFS precedence.  FIXME: Use a topological sort.
    (while (let ((class (pop classes)))
             (cl-pushnew (cl--class-name class) parents)
             (setq classes
                   (append classes
                           (cl--class-parents class)))))
    (nreverse parents)))

(defun cl--generic-struct-specializers (tag &rest _)
  (and (symbolp tag)
       (let ((class (get tag 'cl--class)))
         (when (cl-typep class 'cl-structure-class)
           (cl--generic-class-parents class)))))

(cl-generic-define-generalizer cl--generic-struct-generalizer
  50 #'cl--generic-struct-tag
  #'cl--generic-struct-specializers)

(cl-defmethod cl-generic-generalizers :extra "cl-struct" (type)
  "Support for dispatch on types defined by `cl-defstruct'."
  (or
   (when (symbolp type)
     ;; Use the "cl--struct-class*" (inlinable) functions/macros rather than
     ;; the "cl-struct-*" variants which aren't inlined, so that dispatch can
     ;; take place without requiring cl-lib.
     (let ((class (cl--find-class type)))
       (and (cl-typep class 'cl-structure-class)
            (or (null (cl--struct-class-type class))
		(error "Can't dispatch on cl-struct %S: type is %S"
                     type (cl--struct-class-type class)))
            (progn (cl-assert (null (cl--struct-class-named class))) t)
            (list cl--generic-struct-generalizer))))
   (cl-call-next-method)))

(cl--generic-prefill-dispatchers 0 cl--generic-generalizer)

;;; Dispatch on "system types".

(cl-generic-define-generalizer cl--generic-typeof-generalizer
  ;; FIXME: We could also change `type-of' to return `null' for nil.
  10 (lambda (name &rest _) `(if ,name (type-of ,name) 'null))
  (lambda (tag &rest _)
    (and (symbolp tag) (assq tag cl--typeof-types))))

(cl-defmethod cl-generic-generalizers :extra "typeof" (type)
  "Support for dispatch on builtin types.
See the full list and their hierarchy in `cl--typeof-types'."
  ;; FIXME: Add support for other types accepted by `cl-typep' such
  ;; as `character', `face', `function', ...
  (or
   (and (memq type cl--all-builtin-types)
        (progn
          ;; FIXME: While this wrinkle in the semantics can be occasionally
          ;; problematic, this warning is more often annoying than helpful.
          ;;(if (memq type '(vector array sequence))
          ;;    (message "`%S' also matches CL structs and EIEIO classes"
          ;;             type))
          (list cl--generic-typeof-generalizer)))
   (cl-call-next-method)))

(cl--generic-prefill-dispatchers 0 integer)
(cl--generic-prefill-dispatchers 0 cl--generic-generalizer integer)

;;; Dispatch on major mode.

;; Two parts:
;; - first define a specializer (derived-mode <mode>) to match symbols
;;   representing major modes, while obeying the major mode hierarchy.
;; - then define a context-rewriter so you can write
;;   "&context (major-mode c-mode)" rather than
;;   "&context (major-mode (derived-mode c-mode))".

(defun cl--generic-derived-specializers (mode &rest _)
  ;; FIXME: Handle (derived-mode <mode1> ... <modeN>)
  (let ((specializers ()))
    (while mode
      (push `(derived-mode ,mode) specializers)
      (setq mode (get mode 'derived-mode-parent)))
    (nreverse specializers)))

(cl-generic-define-generalizer cl--generic-derived-generalizer
  90 (lambda (name) `(and (symbolp ,name) (functionp ,name) ,name))
  #'cl--generic-derived-specializers)

(cl-defmethod cl-generic-generalizers ((_specializer (head derived-mode)))
  "Support for (derived-mode MODE) specializers.
Used internally for the (major-mode MODE) context specializers."
  (list cl--generic-derived-generalizer))

(cl-generic-define-context-rewriter major-mode (mode &rest modes)
  `(major-mode ,(if (consp mode)
                    ;;E.g. could be (eql ...)
                    (progn (cl-assert (null modes)) mode)
                  `(derived-mode ,mode . ,modes))))

;;; Support for unloading.

(cl-defmethod loadhist-unload-element ((x (head cl-defmethod)))
  (pcase-let*
      ((`(,name ,qualifiers . ,specializers) (cdr x))
       (generic (cl-generic-ensure-function name 'noerror)))
    (when generic
      (let* ((mt (cl--generic-method-table generic))
             (me (cl--generic-member-method specializers qualifiers mt)))
        (when me
          (setf (cl--generic-method-table generic) (delq (car me) mt)))))))


(provide 'cl-generic)
;;; cl-generic.el ends here

debug log:

solving 10190f4933 ...
found 10190f4933 in https://git.savannah.gnu.org/cgit/emacs.git

(*) Git path names are given by the tree(s) the blob belongs to.
    Blobs themselves have no identifier aside from the hash of its contents.^

Code repositories for project(s) associated with this public inbox

	https://git.savannah.gnu.org/cgit/emacs.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).