Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

   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
/**
 * @copyright
 * ====================================================================
 *    Licensed to the Apache Software Foundation (ASF) under one
 *    or more contributor license agreements.  See the NOTICE file
 *    distributed with this work for additional information
 *    regarding copyright ownership.  The ASF licenses this file
 *    to you under the Apache License, Version 2.0 (the
 *    "License"); you may not use this file except in compliance
 *    with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing,
 *    software distributed under the License is distributed on an
 *    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *    KIND, either express or implied.  See the License for the
 *    specific language governing permissions and limitations
 *    under the License.
 * ====================================================================
 * @endcopyright
 *
 * @file svn_editor.h
 * @brief Tree editing functions and structures
 */

#ifndef SVN_EDITOR_H
#define SVN_EDITOR_H

#include <apr_pools.h>

#include "svn_types.h"
#include "svn_error.h"
#include "svn_io.h"    /* for svn_stream_t  */
#include "svn_delta.h"

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */


/*** Temporarily private stuff (should move to svn_delta.h when Editor
     V2 is made public) ***/

/** Callback to retrieve a node's entire set of properties.  This is
 * needed by the various editor shims in order to effect backwards
 * compatibility.
 *
 * Implementations should set @a *props to the hash of properties
 * associated with @a path in @a base_revision, allocating that hash
 * and its contents in @a result_pool, and should use @a scratch_pool
 * for temporary allocations.
 *
 * @a baton is an implementation-specific closure.
 */
typedef svn_error_t *(*svn_delta_fetch_props_func_t)(
  apr_hash_t **props,
  void *baton,
  const char *path,
  svn_revnum_t base_revision,
  apr_pool_t *result_pool,
  apr_pool_t *scratch_pool
  );

/** Callback to retrieve a node's kind.  This is needed by the various
 * editor shims in order to effect backwards compatibility.
 *
 * Implementations should set @a *kind to the node kind of @a path in
 * @a base_revision, using @a scratch_pool for temporary allocations.
 *
 * @a baton is an implementation-specific closure.
 */
typedef svn_error_t *(*svn_delta_fetch_kind_func_t)(
  svn_node_kind_t *kind,
  void *baton,
  const char *path,
  svn_revnum_t base_revision,
  apr_pool_t *scratch_pool
  );

/** Callback to fetch the name of a file to use as a delta base.
 *
 * Implementations should set @a *filename to the name of a file
 * suitable for use as a delta base for @a path in @a base_revision
 * (allocating @a *filename from @a result_pool), or to @c NULL if the
 * base stream is empty.  @a scratch_pool is provided for temporary
 * allocations.
 *
 * @a baton is an implementation-specific closure.
 */
typedef svn_error_t *(*svn_delta_fetch_base_func_t)(
  const char **filename,
  void *baton,
  const char *path,
  svn_revnum_t base_revision,
  apr_pool_t *result_pool,
  apr_pool_t *scratch_pool
  );

/** Collection of callbacks used for the shim code.  This structure
 * may grow additional fields in the future.  Therefore, always use
 * svn_delta_shim_callbacks_default() to allocate new instances of it.
 */
typedef struct svn_delta_shim_callbacks_t
{
  svn_delta_fetch_props_func_t fetch_props_func;
  svn_delta_fetch_kind_func_t fetch_kind_func;
  svn_delta_fetch_base_func_t fetch_base_func;
  void *fetch_baton;
} svn_delta_shim_callbacks_t;

/** Return a collection of default shim functions in @a result_pool.
 */
svn_delta_shim_callbacks_t *
svn_delta_shim_callbacks_default(apr_pool_t *result_pool);



/** Transforming trees ("editing").
 *
 * In Subversion, we have a number of occasions where we transform a tree
 * from one state into another. This process is called "editing" a tree.
 *
 * In processing a `commit' command:
 * - The client examines its working copy data to determine the set of
 *   changes necessary to transform its base tree into the desired target.
 * - The client networking library delivers that set of changes/operations
 *   across the wire as an equivalent series of network requests (for
 *   example, to svnserve as an ra_svn protocol stream, or to an
 *   Apache httpd server as WebDAV commands)
 * - The server receives those requests and applies the sequence of
 *   operations on a revision, producing a transaction representing the
 *   desired target.
 * - The Subversion server then commits the transaction to the filesystem.
 *
 * In processing an `update' command, the process is reversed:
 * - The Subversion server module talks to the filesystem and computes a
 *   set of changes necessary to bring the client's working copy up to date.
 * - The server serializes this description of changes, and delivers it to
 *   the client.
 * - The client networking library receives that reply, producing a set
 *   of changes/operations to alter the working copy into the revision
 *   requested by the update command.
 * - The working copy library applies those operations to the working copy
 *   to align it with the requested update target.
 *
 * The series of changes (or operations) necessary to transform a tree from
 * one state into another is passed between subsystems using this "editor"
 * interface. The "receiver" edits its tree according to the operations
 * described by the "driver".
 *
 * Note that the driver must have a perfect understanding of the tree which
 * the receiver will be applying edits upon. There is no room for error here,
 * and the interface embodies assumptions/requirements that the driver has
 * about the targeted tree. As a result, this interface is a standardized
 * mechanism of *describing* those change operations, but the intimate
 * knowledge between the driver and the receiver implies some level of
 * coupling between those subsystems.
 *
 * The set of changes, and the data necessary to describe it entirely, is
 * completely unbounded. An addition of one simple 20 GB file might be well
 * past the available memory of a machine processing these operations.
 * As a result, the API to describe the changes is designed to be applied
 * in a sequential (and relatively random-access) model. The operations
 * can be streamed from the driver to the receiver, resulting in the
 * receiver editing its tree to the target state defined by the driver.
 *
 *
 * <h3>History</h3>
 *
 * Classically, Subversion had a notion of a "tree delta" which could be
 * passed around as an independent entity. Theory implied this delta was an
 * entity in its own right, to be used when and where necessary.
 * Unfortunately, this theory did not work well in practice. The producer
 * and consumer of these tree deltas were (and are) tightly coupled. As noted
 * above, the tree delta producer needed to be *totally* aware of the tree
 * that it needed to edit. So rather than telling the delta consumer how to
 * edit its tree, the classic #svn_delta_editor_t interface focused
 * entirely on the tree delta, an intermediate (logical) data structure
 * which was unusable outside of the particular, coupled pairing of producer
 * and consumer. This generation of the API forgoes the logical tree delta
 * entity and directly passes the necessary edits/changes/operations from
 * the producer to the consumer. In our new parlance, one subsystem "drives"
 * a set of operations describing the change, and a "receiver" accepts and
 * applies them to its tree.
 *
 * The classic interface was named #svn_delta_editor_t and was described
 * idiomatically as the "editor interface". This generation of the interface
 * retains the "editor" name for that reason. All notions of a "tree delta"
 * structure are no longer part of this interface.
 *
 * The old interface was purely vtable-based and used a number of special
 * editors which could be interposed between the driver and receiver. Those
 * editors provided cancellation, debugging, and other various operations.
 * While the "interposition" pattern is still possible with this interface,
 * the most common functionality (cancellation and debugging) have been
 * integrated directly into this new editor system.
 *
 *
 * <h3>Implementation Plan</h3>
 * @note This section can be removed after Ev2 is fully implemented.
 *
 * The delta editor is pretty engrained throughout Subversion, so attempting
 * to replace it in situ is somewhat akin to performing open heart surgery
 * while the patient is running a marathon.  However, a viable plan should
 * make things a bit easier, and help parallelize the work.
 *
 * In short, the following items need to be done:
 *  -# Implement backward compatibility wrappers ("shims")
 *  -# Use shims to update editor consumers to Ev2
 *  -# Update editor producers to drive Ev2
 *     - This will largely involve rewriting the RA layers to accept and
 *       send Ev2 commands
 *  -# Optimize consumers and producers to leverage the features of Ev2
 *
 * The shims are largely self-contained, and as of this writing, are almost
 * complete.  They can be released without much ado.  However, they do add
 * <em>significant</em> performance regressions, which make releasing code
 * which is half-delta-editor and half-Ev2 inadvisable.  As such, the updating
 * of producers and consumers to Ev2 will probably need to wait until 1.9,
 * though it could be largely parallelized.
 *
 *
 * @defgroup svn_editor The editor interface
 * @{
 */

/** An abstract object that edits a target tree.
 *
 * @note The term "follow" means at any later time in the editor drive.
 * Terms such as "must", "must not", "required", "shall", "shall not",
 * "should", "should not", "recommended", "may", and "optional" in this
 * document are to be interpreted as described in RFC 2119.
 *
 * @note The editor objects are *not* reentrant. The receiver should not
 * directly or indirectly invoke an editor API with the same object unless
 * it has been marked as explicitly supporting reentrancy during a
 * receiver's callback. This limitation extends to the cancellation
 * callback, too. (This limitation is due to the scratch_pool shared by
 * all callbacks, and cleared after each callback; a reentrant call could
 * clear the outer call's pool). Note that the code itself is reentrant, so
 * there is no problem using the APIs on different editor objects.
 *
 * \n
 * <h3>Life-Cycle</h3>
 *
 * - @b Create: A receiver uses svn_editor_create() to create an
 *    "empty" svn_editor_t.  It cannot be used yet, since it still lacks
 *    actual callback functions.  svn_editor_create() sets the
 *    #svn_editor_t's callback baton and scratch pool that the callback
 *    functions receive, as well as a cancellation callback and baton
 *    (see "Cancellation" below).
 *
 * - @b Set callbacks: The receiver calls svn_editor_setcb_many() or a
 *    succession of the other svn_editor_setcb_*() functions to tell
 *    #svn_editor_t which functions to call when driven by the various
 *    operations.  Callback functions are implemented by the receiver and must
 *    adhere to the @c svn_editor_cb_*_t function types as expected by the
 *    svn_editor_setcb_*() functions. See: \n
 *      svn_editor_cb_many_t \n
 *      svn_editor_setcb_many() \n
 *      or \n
 *      svn_editor_setcb_add_directory() \n
 *      svn_editor_setcb_add_file() \n
 *      svn_editor_setcb_add_symlink() \n
 *      svn_editor_setcb_add_absent() \n
 *      svn_editor_setcb_alter_directory() \n
 *      svn_editor_setcb_alter_file() \n
 *      svn_editor_setcb_alter_symlink() \n
 *      svn_editor_setcb_delete() \n
 *      svn_editor_setcb_copy() \n
 *      svn_editor_setcb_move() \n
 *      svn_editor_setcb_complete() \n
 *      svn_editor_setcb_abort()
 *
 * - @b Drive: The driver is provided with the completed #svn_editor_t
 *    instance. (It is typically passed to a generic driving
 *    API, which could receive the driving editor calls over the network
 *    by providing a proxy #svn_editor_t on the remote side.)
 *    The driver invokes the #svn_editor_t instance's callback functions
 *    according to the restrictions defined below, in order to describe the
 *    entire set of operations necessary to transform the receiver's tree
 *    into the desired target. The callbacks can be invoked using the
 *    svn_editor_*() functions, i.e.: \n
 *      svn_editor_add_directory() \n
 *      svn_editor_add_file() \n
 *      svn_editor_add_symlink() \n
 *      svn_editor_add_absent() \n
 *      svn_editor_alter_directory() \n
 *      svn_editor_alter_file() \n
 *      svn_editor_alter_symlink() \n
 *      svn_editor_delete() \n
 *      svn_editor_copy() \n
 *      svn_editor_move() \n
 *    \n\n
 *    Just before each callback invocation is carried out, the @a cancel_func
 *    that was passed to svn_editor_create() is invoked to poll any
 *    external reasons to cancel the sequence of operations.  Unless it
 *    overrides the cancellation (denoted by #SVN_ERR_CANCELLED), the driver
 *    aborts the transmission by invoking the svn_editor_abort() callback.
 *    Exceptions to this are calls to svn_editor_complete() and
 *    svn_editor_abort(), which cannot be canceled externally.
 *
 * - @b Receive: While the driver invokes operations upon the editor, the
 *    receiver finds its callback functions called with the information
 *    to operate on its tree. Each actual callback function receives those
 *    arguments that the driver passed to the "driving" functions, plus these:
 *    -  @a baton: This is the @a editor_baton pointer originally passed to
 *       svn_editor_create().  It may be freely used by the callback
 *       implementation to store information across all callbacks.
 *    -  @a scratch_pool: This temporary pool is cleared directly after
 *       each callback returns.  See "Pool Usage".
 *    \n\n
 *    If the receiver encounters an error within a callback, it returns an
 *    #svn_error_t*. The driver receives this and aborts transmission.
 *
 * - @b Complete/Abort: The driver will end transmission by calling \n
 *    svn_editor_complete() if successful, or \n
 *    svn_editor_abort() if an error or cancellation occurred.
 * \n\n
 *
 * <h3>Driving Order Restrictions</h3>
 * In order to reduce complexity of callback receivers, the editor callbacks
 * must be driven in adherence to these rules:
 *
 * - If any path is added (with add_*) or deleted/moved, then
 *   an svn_editor_alter_directory() call must be made for its parent
 *   directory with the target/eventual set of children.
 *
 * - svn_editor_add_directory() -- Another svn_editor_add_*() call must
 *   follow for each child mentioned in the @a children argument of any
 *   svn_editor_add_directory() call.
 *
 * - For each node created with add_*, if its parent was created using
 *   svn_editor_add_directory(), then the new child node MUST have been
 *   mentioned in the @a children parameter of the parent's creation.
 *   This allows the parent directory to properly mark the child as
 *   "incomplete" until the child's add_* call arrives.
 *
 * - A path should never be referenced more than once by the add_*, alter_*,
 *   and delete operations (the "Once Rule"). The source path of a copy (and
 *   its children, if a directory) may be copied many times, and are
 *   otherwise subject to the Once Rule. The destination path of a copy
 *   or move may have alter_* operations applied, but not add_* or delete.
 *   If the destination path of a copy or move is a directory,
 *   then its children are subject to the Once Rule. The source path of
 *   a move (and its child paths) may be referenced in add_*, or as the
 *   destination of a copy (where these new or copied nodes are subject
 *   to the Once Rule).
 *
 * - The ancestor of an added, copied-here, moved-here, or
 *   modified node may not be deleted. The ancestor may not be moved
 *   (instead: perform the move, *then* the edits).
 *
 * - svn_editor_delete() must not be used to replace a path -- i.e.
 *   svn_editor_delete() must not be followed by an svn_editor_add_*() on
 *   the same path, nor by an svn_editor_copy() or svn_editor_move() with
 *   the same path as the copy/move target.
 *
 *   Instead of a prior delete call, the add/copy/move callbacks should be
 *   called with the @a replaces_rev argument set to the revision number of
 *   the node at this path that is being replaced.  Note that the path and
 *   revision number are the key to finding any other information about the
 *   replaced node, like node kind, etc.
 *   @todo say which function(s) to use.
 *
 * - svn_editor_delete() must not be used to move a path -- i.e.
 *   svn_editor_delete() must not delete the source path of a previous
 *   svn_editor_copy() call. Instead, svn_editor_move() must be used.
 *   Note: if the desired semantics is one (or more) copies, followed
 *   by a delete... that is fine. It is simply that svn_editor_move()
 *   should be used to describe a semantic move.
 *
 * - One of svn_editor_complete() or svn_editor_abort() must be called
 *   exactly once, which must be the final call the driver invokes.
 *   Invoking svn_editor_complete() must imply that the set of changes has
 *   been transmitted completely and without errors, and invoking
 *   svn_editor_abort() must imply that the transformation was not completed
 *   successfully.
 *
 * - If any callback invocation (besides svn_editor_complete()) returns
 *   with an error, the driver must invoke svn_editor_abort() and stop
 *   transmitting operations.
 * \n\n
 *
 * <h3>Receiving Restrictions</h3>
 *
 * All callbacks must complete their handling of a path before they return.
 * Since future callbacks will never reference this path again (due to the
 * Once Rule), the changes can and should be completed.
 *
 * This restriction is not recursive -- a directory's children may remain
 * incomplete until later callback calls are received.
 *
 * For example, an svn_editor_add_directory() call during an 'update'
 * operation will create the directory itself, including its properties,
 * and will complete any client notification for the directory itself.
 * The immediate children of the added directory, given in @a children,
 * will be recorded in the WC as 'incomplete' and will be completed in the
 * course of the same operation sequence, when the corresponding callbacks
 * for these items are invoked.
 * \n\n
 *
 * <h3>Timing and State</h3>
 * The calls made by the driver to alter the state in the receiver are
 * based on the receiver's *current* state, which includes all prior changes
 * made during the edit.
 *
 * Example: copy A to B; set-props on A; copy A to C. The props on C
 * should reflect the updated properties of A.
 *
 * Example: mv A@N to B; mv C@M to A. The second move cannot be marked as
 * a "replacing" move since it is not replacing A. The node at A was moved
 * away. The second operation is simply moving C to the now-empty path
 * known as A.
 *
 * <h3>Paths</h3>
 * Each driver/receiver implementation of this editor interface must
 * establish the expected root for all the paths sent and received via
 * the callbacks' @a relpath arguments.
 *
 * For example, during an "update", the driver is the repository, as a
 * whole. The receiver may have just a portion of that repository. Here,
 * the receiver could tell the driver which repository URL the working
 * copy refers to, and thus the driver could send @a relpath arguments
 * that are relative to the receiver's working copy.
 *
 * @note Because the source of a copy may be located *anywhere* in the
 * repository, editor drives should typically use the repository root
 * as the negotiated root. This allows the @a src_relpath argument in
 * svn_editor_copy() to specify any possible source.
 * \n\n
 *
 * <h3>Pool Usage</h3>
 * The @a result_pool passed to svn_editor_create() is used to allocate
 * the #svn_editor_t instance, and thus it must not be cleared before the
 * driver has finished driving the editor.
 *
 * The @a scratch_pool passed to each callback invocation is derived from
 * the @a result_pool that was passed to svn_editor_create(). It is
 * cleared directly after each single callback invocation.
 * To allocate memory with a longer lifetime from within a callback
 * function, you may use your own pool kept in the @a editor_baton.
 *
 * The @a scratch_pool passed to svn_editor_create() may be used to help
 * during construction of the #svn_editor_t instance, but it is assumed to
 * live only until svn_editor_create() returns.
 * \n\n
 *
 * <h3>Cancellation</h3>
 * To allow graceful interruption by external events (like a user abort),
 * svn_editor_create() can be passed an #svn_cancel_func_t that is
 * polled every time the driver invokes a callback, just before the
 * actual editor callback implementation is invoked.  If this function
 * decides to return with an error, the driver will receive this error
 * as if the callback function had returned it, i.e. as the result from
 * calling any of the driving functions (e.g. svn_editor_add_directory()).
 * As with any other error, the driver must then invoke svn_editor_abort()
 * and abort the transformation sequence. See #svn_cancel_func_t.
 *
 * The @a cancel_baton argument to svn_editor_create() is passed
 * unchanged to each poll of @a cancel_func.
 *
 * The cancellation function and baton are typically provided by the client
 * context.
 *
 *
 * @todo ### TODO anything missing?
 *
 * @since New in 1.8.
 */
typedef struct svn_editor_t svn_editor_t;

/** The kind of the checksum to be used throughout the #svn_editor_t APIs.
 *
 * @note ### This may change before Ev2 is official released, so just like
 * everything else in this file, please don't rely upon it until then.
 */
#define SVN_EDITOR_CHECKSUM_KIND svn_checksum_sha1


/** These function types define the callback functions a tree delta consumer
 * implements.
 *
 * Each of these "receiving" function types matches a "driving" function,
 * which has the same arguments with these differences:
 *
 * - These "receiving" functions have a @a baton argument, which is the
 *   @a editor_baton originally passed to svn_editor_create(), as well as
 *   a @a scratch_pool argument.
 *
 * - The "driving" functions have an #svn_editor_t* argument, in order to
 *   call the implementations of the function types defined here that are
 *   registered with the given #svn_editor_t instance.
 *
 * Note that any remaining arguments for these function types are explained
 * in the comment for the "driving" functions. Each function type links to
 * its corresponding "driver".
 *
 * @see svn_editor_t, svn_editor_cb_many_t.
 *
 * @defgroup svn_editor_callbacks Editor callback definitions
 * @{
 */

/** @see svn_editor_add_directory(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_add_directory_t)(
  void *baton,
  const char *relpath,
  const apr_array_header_t *children,
  apr_hash_t *props,
  svn_revnum_t replaces_rev,
  apr_pool_t *scratch_pool);

/** @see svn_editor_add_file(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_add_file_t)(
  void *baton,
  const char *relpath,
  const svn_checksum_t *checksum,
  svn_stream_t *contents,
  apr_hash_t *props,
  svn_revnum_t replaces_rev,
  apr_pool_t *scratch_pool);

/** @see svn_editor_add_symlink(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_add_symlink_t)(
  void *baton,
  const char *relpath,
  const char *target,
  apr_hash_t *props,
  svn_revnum_t replaces_rev,
  apr_pool_t *scratch_pool);

/** @see svn_editor_add_absent(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_add_absent_t)(
  void *baton,
  const char *relpath,
  svn_node_kind_t kind,
  svn_revnum_t replaces_rev,
  apr_pool_t *scratch_pool);

/** @see svn_editor_alter_directory(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_alter_directory_t)(
  void *baton,
  const char *relpath,
  svn_revnum_t revision,
  const apr_array_header_t *children,
  apr_hash_t *props,
  apr_pool_t *scratch_pool);

/** @see svn_editor_alter_file(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_alter_file_t)(
  void *baton,
  const char *relpath,
  svn_revnum_t revision,
  const svn_checksum_t *checksum,
  svn_stream_t *contents,
  apr_hash_t *props,
  apr_pool_t *scratch_pool);

/** @see svn_editor_alter_symlink(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_alter_symlink_t)(
  void *baton,
  const char *relpath,
  svn_revnum_t revision,
  const char *target,
  apr_hash_t *props,
  apr_pool_t *scratch_pool);

/** @see svn_editor_delete(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_delete_t)(
  void *baton,
  const char *relpath,
  svn_revnum_t revision,
  apr_pool_t *scratch_pool);

/** @see svn_editor_copy(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_copy_t)(
  void *baton,
  const char *src_relpath,
  svn_revnum_t src_revision,
  const char *dst_relpath,
  svn_revnum_t replaces_rev,
  apr_pool_t *scratch_pool);

/** @see svn_editor_move(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_move_t)(
  void *baton,
  const char *src_relpath,
  svn_revnum_t src_revision,
  const char *dst_relpath,
  svn_revnum_t replaces_rev,
  apr_pool_t *scratch_pool);

/** @see svn_editor_complete(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_complete_t)(
  void *baton,
  apr_pool_t *scratch_pool);

/** @see svn_editor_abort(), svn_editor_t.
 * @since New in 1.8.
 */
typedef svn_error_t *(*svn_editor_cb_abort_t)(
  void *baton,
  apr_pool_t *scratch_pool);

/** @} */


/** These functions create an editor instance so that it can be driven.
 *
 * @defgroup svn_editor_create Editor creation
 * @{
 */

/** Allocate an #svn_editor_t instance from @a result_pool, store
 * @a editor_baton, @a cancel_func and @a cancel_baton in the new instance
 * and return it in @a editor.
 * @a scratch_pool is used for temporary allocations (if any). Note that
 * this is NOT the same @a scratch_pool that is passed to callback functions.
 * @see svn_editor_t
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_create(svn_editor_t **editor,
                  void *editor_baton,
                  svn_cancel_func_t cancel_func,
                  void *cancel_baton,
                  apr_pool_t *result_pool,
                  apr_pool_t *scratch_pool);


/** Return an editor's private baton.
 *
 * In some cases, the baton is required outside of the callbacks. This
 * function returns the private baton for use.
 *
 * @since New in 1.8.
 */
void *
svn_editor_get_baton(const svn_editor_t *editor);


/** Sets the #svn_editor_cb_add_directory_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_add_directory(svn_editor_t *editor,
                               svn_editor_cb_add_directory_t callback,
                               apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_add_file_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_add_file(svn_editor_t *editor,
                          svn_editor_cb_add_file_t callback,
                          apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_add_symlink_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_add_symlink(svn_editor_t *editor,
                             svn_editor_cb_add_symlink_t callback,
                             apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_add_absent_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_add_absent(svn_editor_t *editor,
                            svn_editor_cb_add_absent_t callback,
                            apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_alter_directory_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_alter_directory(svn_editor_t *editor,
                                 svn_editor_cb_alter_directory_t callback,
                                 apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_alter_file_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_alter_file(svn_editor_t *editor,
                            svn_editor_cb_alter_file_t callback,
                            apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_alter_symlink_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_alter_symlink(svn_editor_t *editor,
                               svn_editor_cb_alter_symlink_t callback,
                               apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_delete_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_delete(svn_editor_t *editor,
                        svn_editor_cb_delete_t callback,
                        apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_copy_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_copy(svn_editor_t *editor,
                      svn_editor_cb_copy_t callback,
                      apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_move_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_move(svn_editor_t *editor,
                      svn_editor_cb_move_t callback,
                      apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_complete_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_complete(svn_editor_t *editor,
                          svn_editor_cb_complete_t callback,
                          apr_pool_t *scratch_pool);

/** Sets the #svn_editor_cb_abort_t callback in @a editor
 * to @a callback.
 * @a scratch_pool is used for temporary allocations (if any).
 * @see also svn_editor_setcb_many().
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_abort(svn_editor_t *editor,
                       svn_editor_cb_abort_t callback,
                       apr_pool_t *scratch_pool);


/** Lists a complete set of editor callbacks.
 * This is a convenience structure.
 * @see svn_editor_setcb_many(), svn_editor_create(), svn_editor_t.
 * @since New in 1.8.
 */
typedef struct svn_editor_cb_many_t
{
  svn_editor_cb_add_directory_t cb_add_directory;
  svn_editor_cb_add_file_t cb_add_file;
  svn_editor_cb_add_symlink_t cb_add_symlink;
  svn_editor_cb_add_absent_t cb_add_absent;
  svn_editor_cb_alter_directory_t cb_alter_directory;
  svn_editor_cb_alter_file_t cb_alter_file;
  svn_editor_cb_alter_symlink_t cb_alter_symlink;
  svn_editor_cb_delete_t cb_delete;
  svn_editor_cb_copy_t cb_copy;
  svn_editor_cb_move_t cb_move;
  svn_editor_cb_complete_t cb_complete;
  svn_editor_cb_abort_t cb_abort;

} svn_editor_cb_many_t;

/** Sets all the callback functions in @a editor at once, according to the
 * callback functions stored in @a many.
 * @a scratch_pool is used for temporary allocations (if any).
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_setcb_many(svn_editor_t *editor,
                      const svn_editor_cb_many_t *many,
                      apr_pool_t *scratch_pool);

/** @} */


/** These functions are called by the tree delta driver to edit the target.
 *
 * @see svn_editor_t.
 *
 * @defgroup svn_editor_drive Driving the editor
 * @{
 */

/** Drive @a editor's #svn_editor_cb_add_directory_t callback.
 *
 * Create a new directory at @a relpath. The immediate parent of @a relpath
 * is expected to exist.
 *
 * For descriptions of @a props and @a replaces_rev, see
 * svn_editor_add_file().
 *
 * A complete listing of the immediate children of @a relpath that will be
 * added subsequently is given in @a children. @a children is an array of
 * const char*s, each giving the basename of an immediate child. It is an
 * error to pass NULL for @a children; use an empty array to indicate
 * the new directory will have no children.
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 */
svn_error_t *
svn_editor_add_directory(svn_editor_t *editor,
                         const char *relpath,
                         const apr_array_header_t *children,
                         apr_hash_t *props,
                         svn_revnum_t replaces_rev);

/** Drive @a editor's #svn_editor_cb_add_file_t callback.
 *
 * Create a new file at @a relpath. The immediate parent of @a relpath
 * is expected to exist.
 *
 * The file's contents are specified in @a contents which has a checksum
 * matching @a checksum. Both values must be non-NULL.
 *
 * Set the properties of the new file to @a props, which is an
 * apr_hash_t holding key-value pairs. Each key is a const char* of a
 * property name, each value is a const svn_string_t*. If no properties are
 * being set on the new file, @a props must be the empty hash. It is an
 * error to pass NULL for @a props.
 *
 * If this add is expected to replace a previously existing file, symlink or
 * directory at @a relpath, the revision number of the node to be replaced
 * must be given in @a replaces_rev. Otherwise, @a replaces_rev must be
 * #SVN_INVALID_REVNUM.  Note: it is not allowed to call a "delete" followed
 * by an "add" on the same path. Instead, an "add" with @a replaces_rev set
 * accordingly MUST be used.
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_add_file(svn_editor_t *editor,
                    const char *relpath,
                    const svn_checksum_t *checksum,
                    svn_stream_t *contents,
                    apr_hash_t *props,
                    svn_revnum_t replaces_rev);

/** Drive @a editor's #svn_editor_cb_add_symlink_t callback.
 *
 * Create a new symbolic link at @a relpath, with a link target of @a
 * target. The immediate parent of @a relpath is expected to exist.
 *
 * For descriptions of @a props and @a replaces_rev, see
 * svn_editor_add_file().
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_add_symlink(svn_editor_t *editor,
                       const char *relpath,
                       const char *target,
                       apr_hash_t *props,
                       svn_revnum_t replaces_rev);

/** Drive @a editor's #svn_editor_cb_add_absent_t callback.
 *
 * Create an "absent" node of kind @a kind at @a relpath. The immediate
 * parent of @a relpath is expected to exist.
 * ### TODO @todo explain "absent".
 * ### JAF: What are the allowed values of 'kind'?
 *
 * For a description of @a replaces_rev, see svn_editor_add_file().
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_add_absent(svn_editor_t *editor,
                      const char *relpath,
                      svn_node_kind_t kind,
                      svn_revnum_t replaces_rev);

/** Drive @a editor's #svn_editor_cb_alter_directory_t callback.
 *
 * Alter the properties of the directory at @a relpath.
 *
 * @a revision specifies the revision at which the receiver should
 * expect to find this node. That is, @a relpath at the start of the
 * whole edit and @a relpath at @a revision must lie within the same
 * node-rev (aka location history segment). This information may be used
 * to catch an attempt to alter and out-of-date directory. If the
 * directory does not have a corresponding revision in the repository
 * (e.g. it has not yet been committed), then @a revision should be
 * #SVN_INVALID_REVNUM.
 *
 * If any changes to the set of children will be made in the future of
 * the edit drive, then @a children MUST specify the resulting set of
 * children. See svn_editor_add_directory() for the format of @a children.
 * If not changes will be made, then NULL may be specified.
 *
 * For a description of @a props, see svn_editor_add_file(). If no changes
 * to the properties will be made (ie. only future changes to the set of
 * children), then @a props may be NULL.
 *
 * It is an error to pass NULL for both @a children and @a props.
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_alter_directory(svn_editor_t *editor,
                           const char *relpath,
                           svn_revnum_t revision,
                           const apr_array_header_t *children,
                           apr_hash_t *props);

/** Drive @a editor's #svn_editor_cb_alter_file_t callback.
 *
 * Alter the properties and/or the contents of the file at @a relpath
 * with @a revision as its expected revision. See svn_editor_alter_directory()
 * for more information about @a revision.
 *
 * If @a props is non-NULL, then the properties will be applied.
 *
 * If @a contents is non-NULL, then the stream will be copied to
 * the file, and its checksum must match @a checksum (which must also
 * be non-NULL). If @a contents is NULL, then @a checksum must also
 * be NULL, and no change will be applied to the file's contents.
 *
 * The properties and/or the contents must be changed. It is an error to
 * pass NULL for @a props, @a checksum, and @a contents.
 *
 * For a description of @a checksum and @a contents see
 * svn_editor_add_file(). This function allows @a props to be NULL, but
 * the parameter is otherwise described by svn_editor_add_file().
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_alter_file(svn_editor_t *editor,
                      const char *relpath,
                      svn_revnum_t revision,
                      const svn_checksum_t *checksum,
                      svn_stream_t *contents,
                      apr_hash_t *props);

/** Drive @a editor's #svn_editor_cb_alter_symlink_t callback.
 *
 * Alter the properties and/or the target of the symlink at @a relpath
 * with @a revision as its expected revision. See svn_editor_alter_directory()
 * for more information about @a revision.
 *
 * If @a props is non-NULL, then the properties will be applied.
 *
 * If @a target is non-NULL, then the symlink's target will be updated.
 *
 * The properties and/or the target must be changed. It is an error to
 * pass NULL for @a props and @a target.
 *
 * This function allows @a props to be NULL, but the parameter is
 * otherwise described by svn_editor_add_file().
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_alter_symlink(svn_editor_t *editor,
                         const char *relpath,
                         svn_revnum_t revision,
                         const char *target,
                         apr_hash_t *props);

/** Drive @a editor's #svn_editor_cb_delete_t callback.
 *
 * Delete the existing node at @a relpath, expected to be identical to
 * revision @a revision of that path.
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_delete(svn_editor_t *editor,
                  const char *relpath,
                  svn_revnum_t revision);

/** Drive @a editor's #svn_editor_cb_copy_t callback.
 *
 * Copy the node at @a src_relpath, expected to be identical to revision @a
 * src_revision of that path, to @a dst_relpath.
 *
 * For a description of @a replaces_rev, see svn_editor_add_file().
 *
 * @note See the general instructions on paths for this API. Since the
 * @a src_relpath argument must generally be able to reference any node
 * in the repository, the implication is that the editor's root must be
 * the repository root.
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_copy(svn_editor_t *editor,
                const char *src_relpath,
                svn_revnum_t src_revision,
                const char *dst_relpath,
                svn_revnum_t replaces_rev);

/** Drive @a editor's #svn_editor_cb_move_t callback.
 *
 * Move the node at @a src_relpath to @a dst_relpath.
 *
 * @a src_revision specifies the revision at which the receiver should
 * expect to find this node.  That is, @a src_relpath at the start of
 * the whole edit and @a src_relpath at @a src_revision must lie within
 * the same node-rev (aka history-segment).  This is just like the
 * revisions specified to svn_editor_delete().
 *
 * For a description of @a replaces_rev, see svn_editor_add_file().
 *
 * ### what happens if one side of this move is not "within" the receiver's
 * ### set of paths?
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_move(svn_editor_t *editor,
                const char *src_relpath,
                svn_revnum_t src_revision,
                const char *dst_relpath,
                svn_revnum_t replaces_rev);

/** Drive @a editor's #svn_editor_cb_complete_t callback.
 *
 * Send word that the edit has been completed successfully.
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_complete(svn_editor_t *editor);

/** Drive @a editor's #svn_editor_cb_abort_t callback.
 *
 * Notify that the edit transmission was not successful.
 * ### TODO @todo Shouldn't we add a reason-for-aborting argument?
 *
 * For all restrictions on driving the editor, see #svn_editor_t.
 * @since New in 1.8.
 */
svn_error_t *
svn_editor_abort(svn_editor_t *editor);

/** @} */

/** @} */

/** A temporary API which conditionally inserts a double editor shim
 * into the chain of delta editors.  Used for testing Editor v2.
 *
 * Whether or not the shims are inserted is controlled by a compile-time
 * option in libsvn_delta/compat.c.
 *
 * @note The use of these shims and this API will likely cause all kinds
 * of performance degredation.  (Which is actually a moot point since they
 * don't even work properly yet anyway.)
 */
svn_error_t *
svn_editor__insert_shims(const svn_delta_editor_t **deditor_out,
                         void **dedit_baton_out,
                         const svn_delta_editor_t *deditor_in,
                         void *dedit_baton_in,
                         const char *repos_root,
                         const char *base_dir,
                         svn_delta_shim_callbacks_t *shim_callbacks,
                         apr_pool_t *result_pool,
                         apr_pool_t *scratch_pool);


#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif /* SVN_EDITOR_H */