HTMLPurifier_Strategy_MakeWellFormed::execute()   F
last analyzed

Complexity

Conditions 87
Paths > 20000

Size

Total Lines 449
Code Lines 252

Duplication

Lines 0
Ratio 0 %

Importance

Changes 0
Metric Value
eloc 252
dl 0
loc 449
rs 0
c 0
b 0
f 0
cc 87
nc 28129
nop 3

How to fix   Long Method    Complexity   

Long Method

Small methods make your code easier to understand, in particular if combined with a good name. Besides, if your method is small, finding a good name is usually much easier.

For example, if you find yourself adding comments to a method's body, this is usually a good sign to extract the commented part to a new method, and use the comment as a starting point when coming up with a good name for this new method.

Commonly applied refactorings include:

1
<?php
2
3
/**
4
 * Takes tokens makes them well-formed (balance end tags, etc.)
5
 *
6
 * Specification of the armor attributes this strategy uses:
7
 *
8
 *      - MakeWellFormed_TagClosedError: This armor field is used to
9
 *        suppress tag closed errors for certain tokens [TagClosedSuppress],
10
 *        in particular, if a tag was generated automatically by HTML
11
 *        Purifier, we may rely on our infrastructure to close it for us
12
 *        and shouldn't report an error to the user [TagClosedAuto].
13
 */
14
class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
15
{
16
17
    /**
18
     * Array stream of tokens being processed.
19
     * @type HTMLPurifier_Token[]
20
     */
21
    protected $tokens;
22
23
    /**
24
     * Current token.
25
     * @type HTMLPurifier_Token
26
     */
27
    protected $token;
28
29
    /**
30
     * Zipper managing the true state.
31
     * @type HTMLPurifier_Zipper
32
     */
33
    protected $zipper;
34
35
    /**
36
     * Current nesting of elements.
37
     * @type array
38
     */
39
    protected $stack;
40
41
    /**
42
     * Injectors active in this stream processing.
43
     * @type HTMLPurifier_Injector[]
44
     */
45
    protected $injectors;
46
47
    /**
48
     * Current instance of HTMLPurifier_Config.
49
     * @type HTMLPurifier_Config
50
     */
51
    protected $config;
52
53
    /**
54
     * Current instance of HTMLPurifier_Context.
55
     * @type HTMLPurifier_Context
56
     */
57
    protected $context;
58
59
    /**
60
     * @param HTMLPurifier_Token[] $tokens
61
     * @param HTMLPurifier_Config $config
62
     * @param HTMLPurifier_Context $context
63
     * @return HTMLPurifier_Token[]
64
     * @throws HTMLPurifier_Exception
65
     */
66
    public function execute($tokens, $config, $context)
67
    {
68
        $definition = $config->getHTMLDefinition();
69
70
        // local variables
71
        $generator = new HTMLPurifier_Generator($config, $context);
72
        $escape_invalid_tags = $config->get('Core.EscapeInvalidTags');
73
        // used for autoclose early abortion
74
        $global_parent_allowed_elements = $definition->info_parent_def->child->getAllowedElements($config);
75
        $e = $context->get('ErrorCollector', true);
76
        $i = false; // injector index
77
        list($zipper, $token) = HTMLPurifier_Zipper::fromArray($tokens);
78
        if ($token === NULL) {
79
            return array();
80
        }
81
        $reprocess = false; // whether or not to reprocess the same token
82
        $stack = array();
83
84
        // member variables
85
        $this->stack =& $stack;
86
        $this->tokens =& $tokens;
87
        $this->token =& $token;
88
        $this->zipper =& $zipper;
89
        $this->config = $config;
90
        $this->context = $context;
91
92
        // context variables
93
        $context->register('CurrentNesting', $stack);
94
        $context->register('InputZipper', $zipper);
95
        $context->register('CurrentToken', $token);
96
97
        // -- begin INJECTOR --
98
99
        $this->injectors = array();
100
101
        $injectors = $config->getBatch('AutoFormat');
102
        $def_injectors = $definition->info_injector;
103
        $custom_injectors = $injectors['Custom'];
104
        unset($injectors['Custom']); // special case
105
        foreach ($injectors as $injector => $b) {
106
            // XXX: Fix with a legitimate lookup table of enabled filters
107
            if (strpos($injector, '.') !== false) {
108
                continue;
109
            }
110
            $injector = "HTMLPurifier_Injector_$injector";
111
            if (!$b) {
112
                continue;
113
            }
114
            $this->injectors[] = new $injector;
115
        }
116
        foreach ($def_injectors as $injector) {
117
            // assumed to be objects
118
            $this->injectors[] = $injector;
119
        }
120
        foreach ($custom_injectors as $injector) {
121
            if (!$injector) {
122
                continue;
123
            }
124
            if (is_string($injector)) {
125
                $injector = "HTMLPurifier_Injector_$injector";
126
                $injector = new $injector;
127
            }
128
            $this->injectors[] = $injector;
129
        }
130
131
        // give the injectors references to the definition and context
132
        // variables for performance reasons
133
        foreach ($this->injectors as $ix => $injector) {
134
            $error = $injector->prepare($config, $context);
135
            if (!$error) {
136
                continue;
137
            }
138
            array_splice($this->injectors, $ix, 1); // rm the injector
139
            trigger_error("Cannot enable {$injector->name} injector because $error is not allowed", E_USER_WARNING);
140
        }
141
142
        // -- end INJECTOR --
143
144
        // a note on reprocessing:
145
        //      In order to reduce code duplication, whenever some code needs
146
        //      to make HTML changes in order to make things "correct", the
147
        //      new HTML gets sent through the purifier, regardless of its
148
        //      status. This means that if we add a start token, because it
149
        //      was totally necessary, we don't have to update nesting; we just
150
        //      punt ($reprocess = true; continue;) and it does that for us.
151
152
        // isset is in loop because $tokens size changes during loop exec
153
        for (;;
154
             // only increment if we don't need to reprocess
155
             $reprocess ? $reprocess = false : $token = $zipper->next($token)) {
156
157
            // check for a rewind
158
            if (is_int($i)) {
159
                // possibility: disable rewinding if the current token has a
160
                // rewind set on it already. This would offer protection from
161
                // infinite loop, but might hinder some advanced rewinding.
162
                $rewind_offset = $this->injectors[$i]->getRewindOffset();
163
                if (is_int($rewind_offset)) {
164
                    for ($j = 0; $j < $rewind_offset; $j++) {
165
                        if (empty($zipper->front)) break;
166
                        $token = $zipper->prev($token);
167
                        // indicate that other injectors should not process this token,
168
                        // but we need to reprocess it.  See Note [Injector skips]
169
                        unset($token->skip[$i]);
170
                        $token->rewind = $i;
171
                        if ($token instanceof HTMLPurifier_Token_Start) {
172
                            array_pop($this->stack);
173
                        } elseif ($token instanceof HTMLPurifier_Token_End) {
174
                            $this->stack[] = $token->start;
175
                        }
176
                    }
177
                }
178
                $i = false;
179
            }
180
181
            // handle case of document end
182
            if ($token === NULL) {
183
                // kill processing if stack is empty
184
                if (empty($this->stack)) {
185
                    break;
186
                }
187
188
                // peek
189
                $top_nesting = array_pop($this->stack);
190
                $this->stack[] = $top_nesting;
191
192
                // send error [TagClosedSuppress]
193
                if ($e && !isset($top_nesting->armor['MakeWellFormed_TagClosedError'])) {
194
                    $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by document end', $top_nesting);
195
                }
196
197
                // append, don't splice, since this is the end
198
                $token = new HTMLPurifier_Token_End($top_nesting->name);
199
200
                // punt!
201
                $reprocess = true;
202
                continue;
203
            }
204
205
            //echo '<br>'; printZipper($zipper, $token);//printTokens($this->stack);
206
            //flush();
207
208
            // quick-check: if it's not a tag, no need to process
209
            if (empty($token->is_tag)) {
210
                if ($token instanceof HTMLPurifier_Token_Text) {
211
                    foreach ($this->injectors as $i => $injector) {
212
                        if (isset($token->skip[$i])) {
213
                            // See Note [Injector skips]
214
                            continue;
215
                        }
216
                        if ($token->rewind !== null && $token->rewind !== $i) {
217
                            continue;
218
                        }
219
                        // XXX fuckup
220
                        $r = $token;
221
                        $injector->handleText($r);
222
                        $token = $this->processToken($r, $i);
223
                        $reprocess = true;
224
                        break;
225
                    }
226
                }
227
                // another possibility is a comment
228
                continue;
229
            }
230
231
            if (isset($definition->info[$token->name])) {
232
                $type = $definition->info[$token->name]->child->type;
233
            } else {
234
                $type = false; // Type is unknown, treat accordingly
235
            }
236
237
            // quick tag checks: anything that's *not* an end tag
238
            $ok = false;
239
            if ($type === 'empty' && $token instanceof HTMLPurifier_Token_Start) {
240
                // claims to be a start tag but is empty
241
                $token = new HTMLPurifier_Token_Empty(
242
                    $token->name,
243
                    $token->attr,
244
                    $token->line,
245
                    $token->col,
246
                    $token->armor
247
                );
248
                $ok = true;
249
            } elseif ($type && $type !== 'empty' && $token instanceof HTMLPurifier_Token_Empty) {
250
                // claims to be empty but really is a start tag
251
                // NB: this assignment is required
252
                $old_token = $token;
253
                $token = new HTMLPurifier_Token_End($token->name);
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254
                $token = $this->insertBefore(
255
                    new HTMLPurifier_Token_Start($old_token->name, $old_token->attr, $old_token->line, $old_token->col, $old_token->armor)
256
                );
257
                // punt (since we had to modify the input stream in a non-trivial way)
258
                $reprocess = true;
259
                continue;
260
            } elseif ($token instanceof HTMLPurifier_Token_Empty) {
261
                // real empty token
262
                $ok = true;
263
            } elseif ($token instanceof HTMLPurifier_Token_Start) {
264
                // start tag
265
266
                // ...unless they also have to close their parent
267
                if (!empty($this->stack)) {
268
269
                    // Performance note: you might think that it's rather
270
                    // inefficient, recalculating the autoclose information
271
                    // for every tag that a token closes (since when we
272
                    // do an autoclose, we push a new token into the
273
                    // stream and then /process/ that, before
274
                    // re-processing this token.)  But this is
275
                    // necessary, because an injector can make an
276
                    // arbitrary transformations to the autoclosing
277
                    // tokens we introduce, so things may have changed
278
                    // in the meantime.  Also, doing the inefficient thing is
279
                    // "easy" to reason about (for certain perverse definitions
280
                    // of "easy")
281
282
                    $parent = array_pop($this->stack);
283
                    $this->stack[] = $parent;
284
285
                    $parent_def = null;
286
                    $parent_elements = null;
287
                    $autoclose = false;
288
                    if (isset($definition->info[$parent->name])) {
289
                        $parent_def = $definition->info[$parent->name];
290
                        $parent_elements = $parent_def->child->getAllowedElements($config);
291
                        $autoclose = !isset($parent_elements[$token->name]);
292
                    }
293
294
                    if ($autoclose && $definition->info[$token->name]->wrap) {
295
                        // Check if an element can be wrapped by another
296
                        // element to make it valid in a context (for
297
                        // example, <ul><ul> needs a <li> in between)
298
                        $wrapname = $definition->info[$token->name]->wrap;
299
                        $wrapdef = $definition->info[$wrapname];
300
                        $elements = $wrapdef->child->getAllowedElements($config);
301
                        if (isset($elements[$token->name]) && isset($parent_elements[$wrapname])) {
302
                            $newtoken = new HTMLPurifier_Token_Start($wrapname);
303
                            $token = $this->insertBefore($newtoken);
304
                            $reprocess = true;
305
                            continue;
306
                        }
307
                    }
308
309
                    $carryover = false;
310
                    if ($autoclose && $parent_def->formatting) {
311
                        $carryover = true;
312
                    }
313
314
                    if ($autoclose) {
315
                        // check if this autoclose is doomed to fail
316
                        // (this rechecks $parent, which his harmless)
317
                        $autoclose_ok = isset($global_parent_allowed_elements[$token->name]);
318
                        if (!$autoclose_ok) {
319
                            foreach ($this->stack as $ancestor) {
320
                                $elements = $definition->info[$ancestor->name]->child->getAllowedElements($config);
321
                                if (isset($elements[$token->name])) {
322
                                    $autoclose_ok = true;
323
                                    break;
324
                                }
325
                                if ($definition->info[$token->name]->wrap) {
326
                                    $wrapname = $definition->info[$token->name]->wrap;
327
                                    $wrapdef = $definition->info[$wrapname];
328
                                    $wrap_elements = $wrapdef->child->getAllowedElements($config);
329
                                    if (isset($wrap_elements[$token->name]) && isset($elements[$wrapname])) {
330
                                        $autoclose_ok = true;
331
                                        break;
332
                                    }
333
                                }
334
                            }
335
                        }
336
                        if ($autoclose_ok) {
337
                            // errors need to be updated
338
                            $new_token = new HTMLPurifier_Token_End($parent->name);
339
                            $new_token->start = $parent;
340
                            // [TagClosedSuppress]
341
                            if ($e && !isset($parent->armor['MakeWellFormed_TagClosedError'])) {
342
                                if (!$carryover) {
343
                                    $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag auto closed', $parent);
344
                                } else {
345
                                    $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag carryover', $parent);
346
                                }
347
                            }
348
                            if ($carryover) {
349
                                $element = clone $parent;
350
                                // [TagClosedAuto]
351
                                $element->armor['MakeWellFormed_TagClosedError'] = true;
352
                                $element->carryover = true;
353
                                $token = $this->processToken(array($new_token, $token, $element));
354
                            } else {
355
                                $token = $this->insertBefore($new_token);
356
                            }
357
                        } else {
358
                            $token = $this->remove();
359
                        }
360
                        $reprocess = true;
361
                        continue;
362
                    }
363
364
                }
365
                $ok = true;
366
            }
367
368
            if ($ok) {
369
                foreach ($this->injectors as $i => $injector) {
370
                    if (isset($token->skip[$i])) {
371
                        // See Note [Injector skips]
372
                        continue;
373
                    }
374
                    if ($token->rewind !== null && $token->rewind !== $i) {
375
                        continue;
376
                    }
377
                    $r = $token;
378
                    $injector->handleElement($r);
379
                    $token = $this->processToken($r, $i);
380
                    $reprocess = true;
381
                    break;
382
                }
383
                if (!$reprocess) {
384
                    // ah, nothing interesting happened; do normal processing
385
                    if ($token instanceof HTMLPurifier_Token_Start) {
386
                        $this->stack[] = $token;
387
                    } elseif ($token instanceof HTMLPurifier_Token_End) {
388
                        throw new HTMLPurifier_Exception(
389
                            'Improper handling of end tag in start code; possible error in MakeWellFormed'
390
                        );
391
                    }
392
                }
393
                continue;
394
            }
395
396
            // sanity check: we should be dealing with a closing tag
397
            if (!$token instanceof HTMLPurifier_Token_End) {
398
                throw new HTMLPurifier_Exception('Unaccounted for tag token in input stream, bug in HTML Purifier');
399
            }
400
401
            // make sure that we have something open
402
            if (empty($this->stack)) {
403
                if ($escape_invalid_tags) {
404
                    if ($e) {
405
                        $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag to text');
406
                    }
407
                    $token = new HTMLPurifier_Token_Text($generator->generateFromToken($token));
408
                } else {
409
                    if ($e) {
410
                        $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag removed');
411
                    }
412
                    $token = $this->remove();
413
                }
414
                $reprocess = true;
415
                continue;
416
            }
417
418
            // first, check for the simplest case: everything closes neatly.
419
            // Eventually, everything passes through here; if there are problems
420
            // we modify the input stream accordingly and then punt, so that
421
            // the tokens get processed again.
422
            $current_parent = array_pop($this->stack);
423
            if ($current_parent->name == $token->name) {
424
                $token->start = $current_parent;
425
                foreach ($this->injectors as $i => $injector) {
426
                    if (isset($token->skip[$i])) {
427
                        // See Note [Injector skips]
428
                        continue;
429
                    }
430
                    if ($token->rewind !== null && $token->rewind !== $i) {
431
                        continue;
432
                    }
433
                    $r = $token;
434
                    $injector->handleEnd($r);
435
                    $token = $this->processToken($r, $i);
436
                    $this->stack[] = $current_parent;
437
                    $reprocess = true;
438
                    break;
439
                }
440
                continue;
441
            }
442
443
            // okay, so we're trying to close the wrong tag
444
445
            // undo the pop previous pop
446
            $this->stack[] = $current_parent;
447
448
            // scroll back the entire nest, trying to find our tag.
449
            // (feature could be to specify how far you'd like to go)
450
            $size = count($this->stack);
451
            // -2 because -1 is the last element, but we already checked that
452
            $skipped_tags = false;
453
            for ($j = $size - 2; $j >= 0; $j--) {
454
                if ($this->stack[$j]->name == $token->name) {
455
                    $skipped_tags = array_slice($this->stack, $j);
456
                    break;
457
                }
458
            }
459
460
            // we didn't find the tag, so remove
461
            if ($skipped_tags === false) {
462
                if ($escape_invalid_tags) {
463
                    if ($e) {
464
                        $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag to text');
465
                    }
466
                    $token = new HTMLPurifier_Token_Text($generator->generateFromToken($token));
467
                } else {
468
                    if ($e) {
469
                        $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag removed');
470
                    }
471
                    $token = $this->remove();
472
                }
473
                $reprocess = true;
474
                continue;
475
            }
476
477
            // do errors, in REVERSE $j order: a,b,c with </a></b></c>
478
            $c = count($skipped_tags);
479
            if ($e) {
480
                for ($j = $c - 1; $j > 0; $j--) {
481
                    // notice we exclude $j == 0, i.e. the current ending tag, from
482
                    // the errors... [TagClosedSuppress]
483
                    if (!isset($skipped_tags[$j]->armor['MakeWellFormed_TagClosedError'])) {
484
                        $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by element end', $skipped_tags[$j]);
485
                    }
486
                }
487
            }
488
489
            // insert tags, in FORWARD $j order: c,b,a with </a></b></c>
490
            $replace = array($token);
491
            for ($j = 1; $j < $c; $j++) {
492
                // ...as well as from the insertions
493
                $new_token = new HTMLPurifier_Token_End($skipped_tags[$j]->name);
494
                $new_token->start = $skipped_tags[$j];
495
                array_unshift($replace, $new_token);
496
                if (isset($definition->info[$new_token->name]) && $definition->info[$new_token->name]->formatting) {
497
                    // [TagClosedAuto]
498
                    $element = clone $skipped_tags[$j];
499
                    $element->carryover = true;
500
                    $element->armor['MakeWellFormed_TagClosedError'] = true;
501
                    $replace[] = $element;
502
                }
503
            }
504
            $token = $this->processToken($replace);
505
            $reprocess = true;
506
            continue;
507
        }
508
509
        $context->destroy('CurrentToken');
510
        $context->destroy('CurrentNesting');
511
        $context->destroy('InputZipper');
512
513
        unset($this->injectors, $this->stack, $this->tokens);
514
        return $zipper->toArray($token);
515
    }
516
517
    /**
518
     * Processes arbitrary token values for complicated substitution patterns.
519
     * In general:
520
     *
521
     * If $token is an array, it is a list of tokens to substitute for the
522
     * current token. These tokens then get individually processed. If there
523
     * is a leading integer in the list, that integer determines how many
524
     * tokens from the stream should be removed.
525
     *
526
     * If $token is a regular token, it is swapped with the current token.
527
     *
528
     * If $token is false, the current token is deleted.
529
     *
530
     * If $token is an integer, that number of tokens (with the first token
531
     * being the current one) will be deleted.
532
     *
533
     * @param HTMLPurifier_Token|array|int|bool $token Token substitution value
534
     * @param HTMLPurifier_Injector|int $injector Injector that performed the substitution; default is if
535
     *        this is not an injector related operation.
536
     * @throws HTMLPurifier_Exception
537
     */
538
    protected function processToken($token, $injector = -1)
539
    {
540
        // Zend OpCache miscompiles $token = array($token), so
541
        // avoid this pattern.  See: https://github.com/ezyang/htmlpurifier/issues/108
542
543
        // normalize forms of token
544
        if (is_object($token)) {
545
            $tmp = $token;
546
            $token = array(1, $tmp);
547
        }
548
        if (is_int($token)) {
549
            $tmp = $token;
550
            $token = array($tmp);
551
        }
552
        if ($token === false) {
553
            $token = array(1);
554
        }
555
        if (!is_array($token)) {
556
            throw new HTMLPurifier_Exception('Invalid token type from injector');
557
        }
558
        if (!is_int($token[0])) {
559
            array_unshift($token, 1);
560
        }
561
        if ($token[0] === 0) {
562
            throw new HTMLPurifier_Exception('Deleting zero tokens is not valid');
563
        }
564
565
        // $token is now an array with the following form:
566
        // array(number nodes to delete, new node 1, new node 2, ...)
567
568
        $delete = array_shift($token);
569
        list($old, $r) = $this->zipper->splice($this->token, $delete, $token);
570
571
        if ($injector > -1) {
572
            // See Note [Injector skips]
573
            // Determine appropriate skips.  Here's what the code does:
574
            //  *If* we deleted one or more tokens, copy the skips
575
            //  of those tokens into the skips of the new tokens (in $token).
576
            //  Also, mark the newly inserted tokens as having come from
577
            //  $injector.
578
            $oldskip = isset($old[0]) ? $old[0]->skip : array();
579
            foreach ($token as $object) {
580
                $object->skip = $oldskip;
581
                $object->skip[$injector] = true;
582
            }
583
        }
584
585
        return $r;
586
587
    }
588
589
    /**
590
     * Inserts a token before the current token. Cursor now points to
591
     * this token.  You must reprocess after this.
592
     * @param HTMLPurifier_Token $token
593
     */
594
    private function insertBefore($token)
595
    {
596
        // NB not $this->zipper->insertBefore(), due to positioning
597
        // differences
598
        $splice = $this->zipper->splice($this->token, 0, array($token));
599
600
        return $splice[1];
601
    }
602
603
    /**
604
     * Removes current token. Cursor now points to new token occupying previously
605
     * occupied space.  You must reprocess after this.
606
     */
607
    private function remove()
608
    {
609
        return $this->zipper->delete();
610
    }
611
}
612
613
// Note [Injector skips]
614
// ~~~~~~~~~~~~~~~~~~~~~
615
// When I originally designed this class, the idea behind the 'skip'
616
// property of HTMLPurifier_Token was to help avoid infinite loops
617
// in injector processing.  For example, suppose you wrote an injector
618
// that bolded swear words.  Naively, you might write it so that
619
// whenever you saw ****, you replaced it with <strong>****</strong>.
620
//
621
// When this happens, we will reprocess all of the tokens with the
622
// other injectors.  Now there is an opportunity for infinite loop:
623
// if we rerun the swear-word injector on these tokens, we might
624
// see **** and then reprocess again to get
625
// <strong><strong>****</strong></strong> ad infinitum.
626
//
627
// Thus, the idea of a skip is that once we process a token with
628
// an injector, we mark all of those tokens as having "come from"
629
// the injector, and we never run the injector again on these
630
// tokens.
631
//
632
// There were two more complications, however:
633
//
634
//  - With HTMLPurifier_Injector_RemoveEmpty, we noticed that if
635
//    you had <b><i></i></b>, after you removed the <i></i>, you
636
//    really would like this injector to go back and reprocess
637
//    the <b> tag, discovering that it is now empty and can be
638
//    removed.  So we reintroduced the possibility of infinite looping
639
//    by adding a "rewind" function, which let you go back to an
640
//    earlier point in the token stream and reprocess it with injectors.
641
//    Needless to say, we need to UN-skip the token so it gets
642
//    reprocessed.
643
//
644
//  - Suppose that you successfuly process a token, replace it with
645
//    one with your skip mark, but now another injector wants to
646
//    process the skipped token with another token.  Should you continue
647
//    to skip that new token, or reprocess it?  If you reprocess,
648
//    you can end up with an infinite loop where one injector converts
649
//    <a> to <b>, and then another injector converts it back.  So
650
//    we inherit the skips, but for some reason, I thought that we
651
//    should inherit the skip from the first token of the token
652
//    that we deleted.  Why?  Well, it seems to work OK.
653
//
654
// If I were to redesign this functionality, I would absolutely not
655
// go about doing it this way: the semantics are just not very well
656
// defined, and in any case you probably wanted to operate on trees,
657
// not token streams.
658
659
// vim: et sw=4 sts=4
660