woocommerce-pos / includes / Templates / Barcode_Symbology.php

Barcode_Symbology.php in WCPOS – Point of Sale (POS) plugin for WooCommerce 1.10.6, at includes/Templates/Barcode_Symbology.php

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1	<?php
2	/**
3	* Barcode symbology owner — one map, five render lanes.
4	*
5	* A receipt template names its barcode symbology once (`<barcode type="ean13">`),
6	* but that name has to be translated for every render lane we ship: raw ESC/POS
7	* bytes, raw StarPRNT bytes, Star Document Markup, ePOS-Print XML, and the
8	* picqer rasterizer used by the HTML/PDF path. Each lane spells the same nine
9	* symbologies differently, and two of them disagree about the order of the UPC
10	* pair, so keeping the maps next to the emitters that use them guarantees they
11	* drift. They live here instead, with a matrix test pinning every cell.
12	*
13	* Vendor references:
14	* - ESC/POS: Epson ESC/POS Command Reference, `GS k` (barcode, function B).
15	* - StarPRNT: StarPRNT Command Specifications Ver 1.3E, section 10 (barcode).
16	* - ePOS-Print XML: Epson ePOS-Print XML reference, `<barcode>` element.
17	*
18	* @author Paul Kilmurray <paul@kilbot.com>
19	*
20	* @see http://wcpos.com
21	* @package WCPOS\WooCommercePOS\Templates
22	*/
23
24	namespace WCPOS\WooCommercePOS\Templates;
25
26	use WCPOS\Vendor\Picqer\Barcode\BarcodeGeneratorPNG;
27
28	/**
29	* Barcode_Symbology class.
30	*
31	* All-static and stateless: a pure translation table.
32	*
33	* Shape, and when to change it. The per-lane accessors come in pairs named for
34	* the vendor (escpos_, starprnt_) rather than hanging off a lane-descriptor
35	* object, because the lanes are not uniform: two want an integer selector, two
36	* want a string name, and one wants a picqer constant. A descriptor would make
37	* that return type a union and hand the XML and markup lanes members they never
38	* use. Revisit when either becomes true: a third vendor needs its own payload
39	* encoder, or the matrix test's provider grows past roughly seven columns.
40	*
41	* Known duplication this class does NOT address: emit_centered_text() is
42	* identical in Escpos_Thermal_Emitter and Starprnt_Thermal_Emitter, alongside
43	* eleven text-metric helpers those two files already duplicated before this
44	* class existed. Extracting one of the twelve into a trait would fragment the
45	* set rather than fix it; they belong together in a shared text-layout module,
46	* which is scoped separately. Do not treat this class as the pattern for that
47	* work — a static lookup owner suits a translation table keyed by lane, not
48	* shared behaviour that needs emitter state.
49	*/
50	class Barcode_Symbology {
51	/**
52	* The 1D symbologies WCPOS supports, in canonical (parser) spelling.
53	*
54	* Every lane accessor below is total over this list.
55	*
56	* @var array
57	*/
58	public const SYMBOLOGIES = array(
59	'code128',
60	'code39',
61	'code93',
62	'ean13',
63	'ean8',
64	'upca',
65	'upce',
66	'codabar',
67	'itf',
68	);
69
70	/**
71	* Canonical name for the 2D QR symbology, which is not a 1D barcode.
72	*
73	* @var string
74	*/
75	public const QRCODE = 'qrcode';
76
77	/**
78	* Symbology used when a template names one we do not support.
79	*
80	* Code 128 encodes any printable ASCII, so it is the only symbology that can
81	* carry an arbitrary value without a data constraint of its own.
82	*
83	* @var string
84	*/
85	public const DEFAULT_SYMBOLOGY = 'code128';
86
87	/**
88	* Lane discriminator for the ESC/POS byte emitter.
89	*
90	* @var string
91	*/
92	public const LANE_ESCPOS = 'escpos';
93
94	/**
95	* Lane discriminator for the StarPRNT byte emitter.
96	*
97	* @var string
98	*/
99	public const LANE_STARPRNT = 'starprnt';
100
101	/**
102	* Maximum barcode data bytes either byte lane will transmit.
103	*
104	* ESC/POS function B carries the length in a single byte (`GS k m n`), and
105	* the StarPRNT barcode data field is capped at the same 255 for every
106	* symbology, so one clamp covers both.
107	*
108	* @var int
109	*/
110	public const MAX_DATA_BYTES = 255;
111
112	/**
113	* ESC/POS `GS k` function-B symbology selector (the `m` parameter).
114	*
115	* @var array
116	*/
117	private const ESCPOS_IDS = array(
118	'upca' => 65,
119	'upce' => 66,
120	'ean13' => 67,
121	'ean8' => 68,
122	'code39' => 69,
123	'itf' => 70,
124	'codabar' => 71,
125	'code93' => 72,
126	'code128' => 73,
127	);
128
129	/**
130	* StarPRNT `ESC b n1` symbology selector.
131	*
132	* NOTE: the UPC pair is the inverse of the ESC/POS table above — Star numbers
133	* UPC-E before UPC-A. Do not transcribe one table from the other.
134	*
135	* @var array
136	*/
137	private const STARPRNT_IDS = array(
138	'upce' => 0,
139	'upca' => 1,
140	'ean8' => 2,
141	'ean13' => 3,
142	'code39' => 4,
143	'itf' => 5,
144	'code128' => 6,
145	'code93' => 7,
146	'codabar' => 8,
147	);
148
149	/**
150	* Attribute values for the ePOS-Print XML `<barcode type>` element.
151	*
152	* Only the UPC pair differs from the canonical spelling: ePOS-Print
153	* underscores them, and rejects the unseparated form outright.
154	*
155	* @var array
156	*/
157	private const EPOS_XML_NAMES = array(
158	'upca' => 'upc_a',
159	'upce' => 'upc_e',
160	);
161
162	/**
163	* Symbologies ePOS-Print accepts that WCPOS does not model itself.
164	*
165	* Source: Epson ePOS-Print XML reference, `<barcode>` element. These are
166	* accepted by the printer but absent from self::SYMBOLOGIES, so they are
167	* passed through untranslated instead of being folded to Code 128.
168	*
169	* @var array
170	*/
171	private const EPOS_XML_ONLY_TYPES = array(
172	'jan13',
173	'jan8',
174	'code128_auto',
175	'gs1_128',
176	'gs1_databar_omnidirectional',
177	'gs1_databar_truncated',
178	'gs1_databar_limited',
179	'gs1_databar_expanded',
180	);
181
182	/**
183	* Star Document Markup `[barcode: type ...]` names.
184	*
185	* Star markup is alone in calling Codabar "NW-7".
186	*
187	* @var array
188	*/
189	private const STAR_MARKUP_NAMES = array(
190	'codabar' => 'nw7',
191	);
192
193	/**
194	* ESC/POS Code 128 code-set selector prefixed to the data.
195	*
196	* Function B requires the data to open with a code-set selector; without one
197	* the printer prints nothing and reports no error. Set B carries the full
198	* printable ASCII range, which is what receipt values use.
199	*
200	* @var string
201	*/
202	private const ESCPOS_CODE128_SELECTOR = '{B';
203
204	/**
205	* Reduce a template's barcode type to a canonical name.
206	*
207	* @param string $type The barcode type attribute value.
208	*
209	* @return string A member of self::SYMBOLOGIES, or self::QRCODE.
210	*/
211	public static function normalize( string $type ): string {
212	$normalized = strtolower( trim( $type ) );
213
214	if ( 'qr' === $normalized ) {
215	$normalized = self::QRCODE;
216	}
217
218	// Star markup's spelling of Codabar leaks back in through templates
219	// written against a Star printer; accept it as an alias.
220	if ( 'nw7' === $normalized ) {
221	$normalized = 'codabar';
222	}
223
224	if ( self::QRCODE === $normalized ) {
225	return self::QRCODE;
226	}
227
228	return \in_array( $normalized, self::SYMBOLOGIES, true ) ? $normalized : self::DEFAULT_SYMBOLOGY;
229	}
230
231	/**
232	* Determine whether a barcode type should be rendered as a QR code.
233	*
234	* @param string $type The barcode type attribute value.
235	*
236	* @return bool True when the type is a QR variant.
237	*/
238	public static function is_qr( string $type ): bool {
239	return self::QRCODE === self::normalize( $type );
240	}
241
242	/**
243	* Determine whether a value satisfies a symbology's data constraints.
244	*
245	* A printer given data it cannot encode prints nothing and reports no error,
246	* so callers on the byte lanes check this first and print the value as text
247	* instead of handing the printer a symbol it will silently drop. The same
248	* rule governs the constraints below: where a value would print as a symbol
249	* that scans back as something other than the value asked for, it is
250	* rejected here, because a silently wrong barcode is worse than no barcode.
251	*
252	* The lane is required, not optional. Two symbologies differ between lanes:
253	* UPC-E (ESC/POS accepts the 6-8 digit short form, StarPRNT requires the
254	* full 11-12 digit payload) and Code 128 (the lanes escape and select code
255	* sets differently, so both the alphabet and the encoded length differ).
256	* Defaulting either to one vendor would dress that printer's rules up as a
257	* neutral answer.
258	*
259	* @param string $type The barcode type attribute value.
260	* @param string $value The barcode value.
261	* @param string $lane Lane discriminator: self::LANE_ESCPOS or self::LANE_STARPRNT.
262	*
263	* @return bool True when the value can be encoded.
264	*/
265	public static function is_valid_value( string $type, string $value, string $lane ): bool {
266	$symbology = self::normalize_linear( $type );
267	$length = \strlen( $value );
268
269	switch ( $symbology ) {
270	case 'upca':
271	if ( ! self::is_digits( $value ) ) {
272	return false;
273	}
274	// 11 digits: the printer computes the check digit. 12: the last
275	// digit is the check digit and must already be right.
276	return 11 === $length \|\| ( 12 === $length && self::has_valid_gtin_check_digit( $value ) );
277	case 'upce':
278	// ESC/POS accepts the 6-8 digit short form as well as the full
279	// 11-12 digit form; StarPRNT accepts only the full form. The full
280	// form is a UPC-A payload the printer compresses, so its check
281	// digit is the UPC-A one. The short form's check digit is derived
282	// from an expansion only the printer performs, so it is left to
283	// the printer rather than half-checked here.
284	if ( ! self::is_digits( $value ) ) {
285	return false;
286	}
287	if ( 12 === $length ) {
288	return self::has_valid_gtin_check_digit( $value );
289	}
290	if ( 11 === $length ) {
291	return true;
292	}
293
294	return self::LANE_ESCPOS === $lane && $length >= 6 && $length <= 8;
295	case 'ean13':
296	if ( ! self::is_digits( $value ) ) {
297	return false;
298	}
299
300	return 12 === $length \|\| ( 13 === $length && self::has_valid_gtin_check_digit( $value ) );
301	case 'ean8':
302	if ( ! self::is_digits( $value ) ) {
303	return false;
304	}
305
306	return 7 === $length \|\| ( 8 === $length && self::has_valid_gtin_check_digit( $value ) );
307	case 'code39':
308	return self::is_valid_code39( $value );
309	case 'itf':
310	// Interleaved 2 of 5 encodes digits in pairs, so an odd-length
311	// value cannot be encoded at all.
312	return self::is_digits( $value ) && $length >= 2 && $length <= 254 && 0 === $length % 2;
313	case 'codabar':
314	// The start and stop characters travel in the data itself.
315	return $length >= 2 && $length <= 255 && 1 === preg_match( '/\A[A-Da-d][0-9\$\+\-\.\/:]*[A-Da-d]\z/', $value );
316	case 'code93':
317	return $length >= 1 && $length <= 255 && self::is_ascii( $value )
318	&& ( self::LANE_STARPRNT !== $lane \|\| 0 === preg_match( '/[\x00-\x1f\x7f]/', $value ) );
319	case 'code128':
320	default:
321	return self::is_valid_code128( $value, $lane );
322	}
323	}
324
325	/**
326	* Map a symbology to its ESC/POS `GS k` function-B selector.
327	*
328	* @param string $type The barcode type attribute value.
329	*
330	* @return int The `m` parameter byte.
331	*/
332	public static function escpos_id( string $type ): int {
333	return self::ESCPOS_IDS[ self::normalize_linear( $type ) ] ?? self::ESCPOS_IDS[ self::DEFAULT_SYMBOLOGY ];
334	}
335
336	/**
337	* Build the ESC/POS data bytes for a barcode value.
338	*
339	* Code 128 alone needs a code-set selector prefixed to the data, and needs a
340	* literal `{` doubled so it is not read as one. The prefix counts toward the
341	* transmitted length, so the clamp is applied after it is added.
342	*
343	* @param string $type The barcode type attribute value.
344	* @param string $value The barcode value.
345	*
346	* @return string The data bytes to transmit.
347	*/
348	public static function escpos_payload( string $type, string $value ): string {
349	if ( self::DEFAULT_SYMBOLOGY !== self::normalize_linear( $type ) ) {
350	return substr( $value, 0, self::MAX_DATA_BYTES );
351	}
352
353	$payload = substr( self::escpos_code128_data( $value ), 0, self::MAX_DATA_BYTES );
354
355	// Clamping can split an escaped `{{` pair; a lone trailing `{` would be
356	// read as the start of a code-set selector, so drop it.
357	$trailing_braces = \strlen( $payload ) - \strlen( rtrim( $payload, '{' ) );
358	if ( 1 === $trailing_braces % 2 ) {
359	$payload = substr( $payload, 0, -1 );
360	}
361
362	return $payload;
363	}
364
365	/**
366	* Build the ePOS-Print XML payload for a barcode value.
367	*
368	* Code 128 uses the same `{B` selector and `{{` escaping as the ESC/POS
369	* lane — the ePOS-Print spec defines the data identically. The branch is
370	* keyed on the name ePOS will receive, not on normalize_linear(): that
371	* folds every unmodelled type to Code 128, which would hand `{B` to the
372	* pass-through symbologies in EPOS_XML_ONLY_TYPES (`jan13`, `gs1_128`,
373	* `code128_auto`, …) and silently blank them.
374	*
375	* ePOS barcode data also has its own escape layer on top of the XML text:
376	* `\xnn` is a control byte and `\\` a literal backslash (ePOS-Print XML
377	* manual, <barcode> "escape sequences"). A raw backslash in a value would
378	* therefore be decoded by the printer — `A\x41` scans as `AA` — so every
379	* backslash is doubled first, for every symbology.
380	*
381	* Unlike escpos_payload() there is no MAX_DATA_BYTES clamp here: the
382	* emitter validates the value up front with the ESC/POS rules and falls
383	* back to text, and the data travels as XML rather than a length-prefixed
384	* byte command, so a clamp could only ever produce a wrong-but-scannable
385	* symbol.
386	*
387	* @param string $type The barcode type attribute value.
388	* @param string $value The barcode value.
389	*
390	* @return string The XML barcode payload.
391	*/
392	public static function epos_xml_payload( string $type, string $value ): string {
393	$value = self::epos_xml_escape_data( $value );
394
395	if ( self::DEFAULT_SYMBOLOGY === self::epos_xml_name( $type ) ) {
396	return self::escpos_code128_data( $value );
397	}
398
399	return $value;
400	}
401
402	/**
403	* Apply the ePOS-Print barcode/symbol data escape layer to a value.
404	*
405	* Shared by <barcode> and <symbol> (QR) data, which use the same
406	* `\xnn` / `\\` escape sequences.
407	*
408	* @param string $value The raw value.
409	*
410	* @return string The value with literal backslashes doubled.
411	*/
412	public static function epos_xml_escape_data( string $value ): string {
413	return str_replace( '\\', '\\\\', $value );
414	}
415
416	/**
417	* Map a symbology to its StarPRNT `ESC b n1` selector.
418	*
419	* @param string $type The barcode type attribute value.
420	*
421	* @return int The `n1` parameter byte.
422	*/
423	public static function starprnt_id( string $type ): int {
424	return self::STARPRNT_IDS[ self::normalize_linear( $type ) ] ?? self::STARPRNT_IDS[ self::DEFAULT_SYMBOLOGY ];
425	}
426
427	/**
428	* Build the StarPRNT data bytes for a barcode value.
429	*
430	* StarPRNT escapes Code 128 with `%`, not `{`: `%0` is a literal `%`, and
431	* `%6`/`%7`/`%8` select code sets A/B/C. Omitting the start code is legal —
432	* the printer auto-selects — so, unlike ESC/POS, no selector is prefixed.
433	*
434	* @param string $type The barcode type attribute value.
435	* @param string $value The barcode value.
436	*
437	* @return string The data bytes to transmit.
438	*/
439	public static function starprnt_payload( string $type, string $value ): string {
440	if ( self::DEFAULT_SYMBOLOGY !== self::normalize_linear( $type ) ) {
441	return substr( $value, 0, self::MAX_DATA_BYTES );
442	}
443
444	$payload = substr( self::starprnt_code128_data( $value ), 0, self::MAX_DATA_BYTES );
445
446	// Clamping can split an escaped `%0` pair. Star reads `%` plus the byte
447	// after it as an escape, and the next byte on the wire is the RS that
448	// terminates the barcode — so a lone trailing `%` eats the terminator and
449	// the printer keeps consuming the rest of the receipt as barcode data.
450	// Unlike an unprintable symbol, that failure is not self-limiting.
451	$trailing_percents = \strlen( $payload ) - \strlen( rtrim( $payload, '%' ) );
452	if ( 1 === $trailing_percents % 2 ) {
453	$payload = substr( $payload, 0, -1 );
454	}
455
456	return $payload;
457	}
458
459	/**
460	* Map a symbology to its Star Document Markup name.
461	*
462	* @param string $type The barcode type attribute value.
463	*
464	* @return string The `[barcode: type ...]` name.
465	*/
466	public static function star_markup_name( string $type ): string {
467	$symbology = self::normalize_linear( $type );
468
469	return self::STAR_MARKUP_NAMES[ $symbology ] ?? $symbology;
470	}
471
472	/**
473	* Map a symbology to its ePOS-Print XML `<barcode type>` value.
474	*
475	* @param string $type The barcode type attribute value.
476	*
477	* @return string The attribute value.
478	*/
479	public static function epos_xml_name( string $type ): string {
480	$requested = strtolower( trim( $type ) );
481
482	// ePOS-Print accepts symbologies WCPOS does not model, and the `type`
483	// attribute is free-form, so a template may legitimately ask for one.
484	// Folding those to Code 128 would silently downgrade a working GS1-128
485	// to a scannable-but-wrong symbol, so anything ePOS itself accepts is
486	// passed straight through. A name neither we nor ePOS recognise still
487	// falls back to Code 128 rather than being handed to the printer, which
488	// would reject the element and print nothing at all.
489	if ( \in_array( $requested, self::EPOS_XML_ONLY_TYPES, true ) ) {
490	return $requested;
491	}
492
493	$symbology = self::normalize_linear( $type );
494
495	return self::EPOS_XML_NAMES[ $symbology ] ?? $symbology;
496	}
497
498	/**
499	* Map a symbology to its picqer generator constant.
500	*
501	* @param string $type The barcode type attribute value.
502	*
503	* @return string The picqer TYPE_* constant value.
504	*/
505	public static function picqer_type( string $type ): string {
506	$map = array(
507	'code128' => BarcodeGeneratorPNG::TYPE_CODE_128,
508	'code39' => BarcodeGeneratorPNG::TYPE_CODE_39,
509	'code93' => BarcodeGeneratorPNG::TYPE_CODE_93,
510	'ean13' => BarcodeGeneratorPNG::TYPE_EAN_13,
511	'ean8' => BarcodeGeneratorPNG::TYPE_EAN_8,
512	'upca' => BarcodeGeneratorPNG::TYPE_UPC_A,
513	'upce' => BarcodeGeneratorPNG::TYPE_UPC_E,
514	'codabar' => BarcodeGeneratorPNG::TYPE_CODABAR,
515	'itf' => BarcodeGeneratorPNG::TYPE_INTERLEAVED_2_5,
516	);
517
518	return $map[ self::normalize_linear( $type ) ] ?? $map[ self::DEFAULT_SYMBOLOGY ];
519	}
520
521	/**
522	* Build the unclamped ESC/POS Code 128 data bytes for a value.
523	*
524	* Split out from escpos_payload() so is_valid_value() can measure the
525	* encoded length. The selector and the doubled braces both count toward
526	* the 255-byte limit, so a value that fits before escaping can overflow
527	* after it — and the clamp would then print a shortened barcode that scans
528	* cleanly as the wrong value.
529	*
530	* @param string $value The barcode value.
531	*
532	* @return string The encoded data, before any length clamp.
533	*/
534	private static function escpos_code128_data( string $value ): string {
535	return self::ESCPOS_CODE128_SELECTOR . str_replace( '{', '{{', $value );
536	}
537
538	/**
539	* Build the unclamped StarPRNT Code 128 data bytes for a value.
540	*
541	* @param string $value The barcode value.
542	*
543	* @return string The encoded data, before any length clamp.
544	*/
545	private static function starprnt_code128_data( string $value ): string {
546	return str_replace( '%', '%0', $value );
547	}
548
549	/**
550	* Whether a value can be encoded as Code 128 on a given lane.
551	*
552	* Two lane-specific constraints, both of which fail silently on the printer:
553	*
554	* - Alphabet. escpos_payload() always selects code set B, which encodes
555	* ASCII 32-126 only; a tab, LF or CR needs set A, so an ESC/POS printer
556	* drops the symbol. StarPRNT auto-selects its code set, but its barcode
557	* data is RS-terminated, so control bytes cannot safely travel in it.
558	* - Length. The limit applies to the encoded bytes, not the merchant's
559	* value: ESC/POS adds a two-byte selector and doubles every `{`, StarPRNT
560	* doubles every `%`. A value that only overflows once escaped would be
561	* clamped into a shorter barcode that still scans — as the wrong value —
562	* so it is rejected here and printed as text instead.
563	*
564	* Epson's minimum of n >= 2 counts the `{B` selector, so a one-character
565	* value is legal on the wire (n = 3).
566	*
567	* @param string $value The barcode value.
568	* @param string $lane Lane discriminator: self::LANE_ESCPOS or self::LANE_STARPRNT.
569	*
570	* @return bool True when the value can be encoded.
571	*/
572	private static function is_valid_code128( string $value, string $lane ): bool {
573	if ( self::LANE_ESCPOS === $lane ) {
574	if ( 1 !== preg_match( '/\A[\x20-\x7e]+\z/', $value ) ) {
575	return false;
576	}
577
578	return \strlen( self::escpos_code128_data( $value ) ) <= self::MAX_DATA_BYTES;
579	}
580
581	if ( '' === $value \|\| ! self::is_ascii( $value ) \|\| 1 === preg_match( '/[\x00-\x1f\x7f]/', $value ) ) {
582	return false;
583	}
584
585	return \strlen( self::starprnt_code128_data( $value ) ) <= self::MAX_DATA_BYTES;
586	}
587
588	/**
589	* Whether a value can be encoded as Code 39.
590	*
591	* `*` is the start/stop sentinel, not data. A printer that finds one in the
592	* middle of the value ends the symbol there, so `AB*CD` scans back as `AB`.
593	* A matching leading and trailing pair is accepted because that is how a
594	* value copied off another system's barcode is usually written; anything
595	* else is rejected and printed as text.
596	*
597	* @param string $value The barcode value.
598	*
599	* @return bool True when the value can be encoded.
600	*/
601	private static function is_valid_code39( string $value ): bool {
602	$length = \strlen( $value );
603	if ( $length < 1 \|\| $length > 255 ) {
604	return false;
605	}
606
607	$body = $value;
608	if ( $length >= 2 && '' === $value[0] && '' === $value[ $length - 1 ] ) {
609	$body = substr( $value, 1, -1 );
610	}
611
612	return 1 === preg_match( '/\A[0-9A-Z \$%\+\-\.\/]+\z/', $body );
613	}
614
615	/**
616	* Whether a GTIN's trailing digit is the correct mod-10 check digit.
617	*
618	* EAN-13, EAN-8 and UPC-A share one rule: weight the digits 3 and 1
619	* alternately from the one immediately left of the check digit, then the
620	* check digit is whatever brings the total to a multiple of ten. UPC-E's
621	* full 12-digit form is a UPC-A payload, so it uses the same rule.
622	*
623	* A wrong check digit is not a harmless typo. The printer either drops the
624	* symbol or prints one encoding a different number from the human-readable
625	* value beside it, and both outcomes are worse than the text fallback.
626	*
627	* @param string $digits An all-digit value whose last character is the check digit.
628	*
629	* @return bool True when the check digit is correct.
630	*/
631	private static function has_valid_gtin_check_digit( string $digits ): bool {
632	$length = \strlen( $digits );
633	if ( $length < 2 ) {
634	return false;
635	}
636
637	$sum = 0;
638	for ( $index = $length - 2; $index >= 0; $index-- ) {
639	$weight = 0 === ( $length - 2 - $index ) % 2 ? 3 : 1;
640	$sum += (int) $digits[ $index ] * $weight;
641	}
642
643	return ( ( 10 - ( $sum % 10 ) ) % 10 ) === (int) $digits[ $length - 1 ];
644	}
645
646	/**
647	* Normalize to a 1D symbology, folding QR onto the default.
648	*
649	* The lane accessors are only ever reached for `barcode` AST nodes; a QR type
650	* arriving here means a caller routed a node wrongly, and Code 128 keeps the
651	* value printable rather than emitting an unencodable symbology id.
652	*
653	* @param string $type The barcode type attribute value.
654	*
655	* @return string A member of self::SYMBOLOGIES.
656	*/
657	private static function normalize_linear( string $type ): string {
658	$symbology = self::normalize( $type );
659
660	return self::QRCODE === $symbology ? self::DEFAULT_SYMBOLOGY : $symbology;
661	}
662
663	/**
664	* Whether a value is a non-empty run of ASCII digits.
665	*
666	* @param string $value The value to test.
667	*
668	* @return bool True when the value is all digits.
669	*/
670	private static function is_digits( string $value ): bool {
671	return 1 === preg_match( '/\A[0-9]+\z/', $value );
672	}
673
674	/**
675	* Whether every byte of a value is in the 0-127 range printers accept.
676	*
677	* @param string $value The value to test.
678	*
679	* @return bool True when the value is 7-bit clean.
680	*/
681	private static function is_ascii( string $value ): bool {
682	return 1 !== preg_match( '/[\x80-\xff]/', $value );
683	}
684	}
685