Create "LanguageCode" rule

docs/LanguageCode.md

@@ -0,0 +1,20 @@
+# LanguageCode
+
+- `v::languageCode()`
+
+Validates a language code based on ISO 639:
+
+```php
+v::languageCode()->validate('pt'); // true
+v::languageCode()->validate('en'); // true
+v::languageCode()->validate('it'); // true
+v::languageCode('alpha-3')->validate('ita'); // true
+v::languageCode('alpha-3')->validate('eng'); // true
+```
+
+You can choose between alpha-2 and alpha-3, alpha-2 is set by default.
+
+***
+See also:
+
+  * [CountryCode](CountryCode.md)

docs/VALIDATORS.md

@@ -139,6 +139,7 @@
 
   * [CountryCode](CountryCode.md)
   * [CurrencyCode](CurrencyCode.md)
+  * [LanguageCode](LanguageCode.md)
   * [PostalCode](PostalCode.md)
   * [SubdivisionCode](SubdivisionCode.md)
   * [Tld](Tld.md)
@@ -254,6 +255,7 @@
   * [KeyNested](KeyNested.md)
   * [KeySet](KeySet.md)
   * [KeyValue](KeyValue.md)
+  * [LanguageCode](LanguageCode.md)
   * [LeapDate](LeapDate.md)
   * [LeapYear](LeapYear.md)
   * [Length](Length.md)

library/Exceptions/LanguageCodeException.php

@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of Respect/Validation.
+ *
+ * (c) Alexandre Gomes Gaigalas <alexandre@gaigalas.net>
+ *
+ * For the full copyright and license information, please view the "LICENSE.md"
+ * file that was distributed with this source code.
+ */
+
+namespace Respect\Validation\Exceptions;
+
+class LanguageCodeException extends ValidationException
+{
+    public static $defaultTemplates = [
+        self::MODE_DEFAULT => [
+            self::STANDARD => '{{name}} must be a valid language',
+        ],
+        self::MODE_NEGATIVE => [
+            self::STANDARD => '{{name}} must not be a valid language',
+        ]
+    ];
+}

library/Rules/LanguageCode.php

@@ -0,0 +1,564 @@
+<?php
+
+/*
+ * This file is part of Respect/Validation.
+ *
+ * (c) Alexandre Gomes Gaigalas <alexandre@gaigalas.net>
+ *
+ * For the full copyright and license information, please view the "LICENSE.md"
+ * file that was distributed with this source code.
+ */
+
+namespace Respect\Validation\Rules;
+
+use Respect\Validation\Exceptions\ComponentException;
+
+/**
+ * Validates languages in ISO 639.
+ */
+class LanguageCode extends AbstractRule
+{
+    const ALPHA2 = 'alpha-2';
+    const ALPHA3 = 'alpha-3';
+
+    /**
+     * @link http://www.loc.gov/standards/iso639-2/ISO-639-2_utf-8.txt
+     *
+     * @var array
+     */
+    protected $languageCodeList = [
+        ['AA', 'AAR'], // AFAR
+        ['AB', 'ABK'], // ABKHAZIAN
+        ['', 'ACE'], // ACHINESE
+        ['', 'ACH'], // ACOLI
+        ['', 'ADA'], // ADANGME
+        ['', 'ADY'], // ADYGHE; ADYGEI
+        ['', 'AFA'], // AFRO-ASIATIC LANGUAGES
+        ['', 'AFH'], // AFRIHILI
+        ['AF', 'AFR'], // AFRIKAANS
+        ['', 'AIN'], // AINU
+        ['AK', 'AKA'], // AKAN
+        ['', 'AKK'], // AKKADIAN
+        ['SQ', 'ALB'], // ALBANIAN
+        ['', 'ALE'], // ALEUT
+        ['', 'ALG'], // ALGONQUIAN LANGUAGES
+        ['', 'ALT'], // SOUTHERN ALTAI
+        ['AM', 'AMH'], // AMHARIC
+        ['', 'ANG'], // ENGLISH, OLD (CA.450-1100)
+        ['', 'ANP'], // ANGIKA
+        ['', 'APA'], // APACHE LANGUAGES
+        ['AR', 'ARA'], // ARABIC
+        ['', 'ARC'], // OFFICIAL ARAMAIC (700-300 BCE); IMPERIAL ARAMAIC (700-300 BCE)
+        ['AN', 'ARG'], // ARAGONESE
+        ['HY', 'ARM'], // ARMENIAN
+        ['', 'ARN'], // MAPUDUNGUN; MAPUCHE
+        ['', 'ARP'], // ARAPAHO
+        ['', 'ART'], // ARTIFICIAL LANGUAGES
+        ['', 'ARW'], // ARAWAK
+        ['AS', 'ASM'], // ASSAMESE
+        ['', 'AST'], // ASTURIAN; BABLE; LEONESE; ASTURLEONESE
+        ['', 'ATH'], // ATHAPASCAN LANGUAGES
+        ['', 'AUS'], // AUSTRALIAN LANGUAGES
+        ['AV', 'AVA'], // AVARIC
+        ['AE', 'AVE'], // AVESTAN
+        ['', 'AWA'], // AWADHI
+        ['AY', 'AYM'], // AYMARA
+        ['AZ', 'AZE'], // AZERBAIJANI
+        ['', 'BAD'], // BANDA LANGUAGES
+        ['', 'BAI'], // BAMILEKE LANGUAGES
+        ['BA', 'BAK'], // BASHKIR
+        ['', 'BAL'], // BALUCHI
+        ['BM', 'BAM'], // BAMBARA
+        ['', 'BAN'], // BALINESE
+        ['EU', 'BAQ'], // BASQUE
+        ['', 'BAS'], // BASA
+        ['', 'BAT'], // BALTIC LANGUAGES
+        ['', 'BEJ'], // BEJA; BEDAWIYET
+        ['BE', 'BEL'], // BELARUSIAN
+        ['', 'BEM'], // BEMBA
+        ['BN', 'BEN'], // BENGALI
+        ['', 'BER'], // BERBER LANGUAGES
+        ['', 'BHO'], // BHOJPURI
+        ['BH', 'BIH'], // BIHARI LANGUAGES
+        ['', 'BIK'], // BIKOL
+        ['', 'BIN'], // BINI; EDO
+        ['BI', 'BIS'], // BISLAMA
+        ['', 'BLA'], // SIKSIKA
+        ['', 'BNT'], // BANTU (OTHER)
+        ['BS', 'BOS'], // BOSNIAN
+        ['', 'BRA'], // BRAJ
+        ['BR', 'BRE'], // BRETON
+        ['', 'BTK'], // BATAK LANGUAGES
+        ['', 'BUA'], // BURIAT
+        ['', 'BUG'], // BUGINESE
+        ['BG', 'BUL'], // BULGARIAN
+        ['MY', 'BUR'], // BURMESE
+        ['', 'BYN'], // BLIN; BILIN
+        ['', 'CAD'], // CADDO
+        ['', 'CAI'], // CENTRAL AMERICAN INDIAN LANGUAGES
+        ['', 'CAR'], // GALIBI CARIB
+        ['CA', 'CAT'], // CATALAN; VALENCIAN
+        ['', 'CAU'], // CAUCASIAN LANGUAGES
+        ['', 'CEB'], // CEBUANO
+        ['', 'CEL'], // CELTIC LANGUAGES
+        ['CH', 'CHA'], // CHAMORRO
+        ['', 'CHB'], // CHIBCHA
+        ['CE', 'CHE'], // CHECHEN
+        ['', 'CHG'], // CHAGATAI
+        ['ZH', 'CHI'], // CHINESE
+        ['', 'CHK'], // CHUUKESE
+        ['', 'CHM'], // MARI
+        ['', 'CHN'], // CHINOOK JARGON
+        ['', 'CHO'], // CHOCTAW
+        ['', 'CHP'], // CHIPEWYAN; DENE SULINE
+        ['', 'CHR'], // CHEROKEE
+        ['CU', 'CHU'], // CHURCH SLAVIC; OLD SLAVONIC; CHURCH SLAVONIC; OLD BULGARIAN; OLD CHURCH SLAVONIC
+        ['CV', 'CHV'], // CHUVASH
+        ['', 'CHY'], // CHEYENNE
+        ['', 'CMC'], // CHAMIC LANGUAGES
+        ['', 'COP'], // COPTIC
+        ['KW', 'COR'], // CORNISH
+        ['CO', 'COS'], // CORSICAN
+        ['', 'CPE'], // CREOLES AND PIDGINS, ENGLISH BASED
+        ['', 'CPF'], // CREOLES AND PIDGINS, FRENCH-BASED
+        ['', 'CPP'], // CREOLES AND PIDGINS, PORTUGUESE-BASED
+        ['CR', 'CRE'], // CREE
+        ['', 'CRH'], // CRIMEAN TATAR; CRIMEAN TURKISH
+        ['', 'CRP'], // CREOLES AND PIDGINS
+        ['', 'CSB'], // KASHUBIAN
+        ['', 'CUS'], // CUSHITIC LANGUAGES
+        ['CS', 'CZE'], // CZECH
+        ['', 'DAK'], // DAKOTA
+        ['DA', 'DAN'], // DANISH
+        ['', 'DAR'], // DARGWA
+        ['', 'DAY'], // LAND DAYAK LANGUAGES
+        ['', 'DEL'], // DELAWARE
+        ['', 'DEN'], // SLAVE (ATHAPASCAN)
+        ['', 'DGR'], // DOGRIB
+        ['', 'DIN'], // DINKA
+        ['DV', 'DIV'], // DIVEHI; DHIVEHI; MALDIVIAN
+        ['', 'DOI'], // DOGRI
+        ['', 'DRA'], // DRAVIDIAN LANGUAGES
+        ['', 'DSB'], // LOWER SORBIAN
+        ['', 'DUA'], // DUALA
+        ['', 'DUM'], // DUTCH, MIDDLE (CA.1050-1350)
+        ['NL', 'DUT'], // DUTCH; FLEMISH
+        ['', 'DYU'], // DYULA
+        ['DZ', 'DZO'], // DZONGKHA
+        ['', 'EFI'], // EFIK
+        ['', 'EGY'], // EGYPTIAN (ANCIENT)
+        ['', 'EKA'], // EKAJUK
+        ['', 'ELX'], // ELAMITE
+        ['EN', 'ENG'], // ENGLISH
+        ['', 'ENM'], // ENGLISH, MIDDLE (1100-1500)
+        ['EO', 'EPO'], // ESPERANTO
+        ['ET', 'EST'], // ESTONIAN
+        ['EE', 'EWE'], // EWE
+        ['', 'EWO'], // EWONDO
+        ['', 'FAN'], // FANG
+        ['FO', 'FAO'], // FAROESE
+        ['', 'FAT'], // FANTI
+        ['FJ', 'FIJ'], // FIJIAN
+        ['', 'FIL'], // FILIPINO; PILIPINO
+        ['FI', 'FIN'], // FINNISH
+        ['', 'FIU'], // FINNO-UGRIAN LANGUAGES
+        ['', 'FON'], // FON
+        ['FR', 'FRE'], // FRENCH
+        ['', 'FRM'], // FRENCH, MIDDLE (CA.1400-1600)
+        ['', 'FRO'], // FRENCH, OLD (842-CA.1400)
+        ['', 'FRR'], // NORTHERN FRISIAN
+        ['', 'FRS'], // EASTERN FRISIAN
+        ['FY', 'FRY'], // WESTERN FRISIAN
+        ['FF', 'FUL'], // FULAH
+        ['', 'FUR'], // FRIULIAN
+        ['', 'GAA'], // GA
+        ['', 'GAY'], // GAYO
+        ['', 'GBA'], // GBAYA
+        ['', 'GEM'], // GERMANIC LANGUAGES
+        ['KA', 'GEO'], // GEORGIAN
+        ['DE', 'GER'], // GERMAN
+        ['', 'GEZ'], // GEEZ
+        ['', 'GIL'], // GILBERTESE
+        ['GD', 'GLA'], // GAELIC; SCOTTISH GAELIC
+        ['GA', 'GLE'], // IRISH
+        ['GL', 'GLG'], // GALICIAN
+        ['GV', 'GLV'], // MANX
+        ['', 'GMH'], // GERMAN, MIDDLE HIGH (CA.1050-1500)
+        ['', 'GOH'], // GERMAN, OLD HIGH (CA.750-1050)
+        ['', 'GON'], // GONDI
+        ['', 'GOR'], // GORONTALO
+        ['', 'GOT'], // GOTHIC
+        ['', 'GRB'], // GREBO
+        ['', 'GRC'], // GREEK, ANCIENT (TO 1453)
+        ['EL', 'GRE'], // GREEK, MODERN (1453-)
+        ['GN', 'GRN'], // GUARANI
+        ['', 'GSW'], // SWISS GERMAN; ALEMANNIC; ALSATIAN
+        ['GU', 'GUJ'], // GUJARATI
+        ['', 'GWI'], // GWICH'IN
+        ['', 'HAI'], // HAIDA
+        ['HT', 'HAT'], // HAITIAN; HAITIAN CREOLE
+        ['HA', 'HAU'], // HAUSA
+        ['', 'HAW'], // HAWAIIAN
+        ['HE', 'HEB'], // HEBREW
+        ['HZ', 'HER'], // HERERO
+        ['', 'HIL'], // HILIGAYNON
+        ['', 'HIM'], // HIMACHALI LANGUAGES; WESTERN PAHARI LANGUAGES
+        ['HI', 'HIN'], // HINDI
+        ['', 'HIT'], // HITTITE
+        ['', 'HMN'], // HMONG; MONG
+        ['HO', 'HMO'], // HIRI MOTU
+        ['HR', 'HRV'], // CROATIAN
+        ['', 'HSB'], // UPPER SORBIAN
+        ['HU', 'HUN'], // HUNGARIAN
+        ['', 'HUP'], // HUPA
+        ['', 'IBA'], // IBAN
+        ['IG', 'IBO'], // IGBO
+        ['IS', 'ICE'], // ICELANDIC
+        ['IO', 'IDO'], // IDO
+        ['II', 'III'], // SICHUAN YI; NUOSU
+        ['', 'IJO'], // IJO LANGUAGES
+        ['IU', 'IKU'], // INUKTITUT
+        ['IE', 'ILE'], // INTERLINGUE; OCCIDENTAL
+        ['', 'ILO'], // ILOKO
+        ['IA', 'INA'], // INTERLINGUA (INTERNATIONAL AUXILIARY LANGUAGE ASSOCIATION)
+        ['', 'INC'], // INDIC LANGUAGES
+        ['ID', 'IND'], // INDONESIAN
+        ['', 'INE'], // INDO-EUROPEAN LANGUAGES
+        ['', 'INH'], // INGUSH
+        ['IK', 'IPK'], // INUPIAQ
+        ['', 'IRA'], // IRANIAN LANGUAGES
+        ['', 'IRO'], // IROQUOIAN LANGUAGES
+        ['IT', 'ITA'], // ITALIAN
+        ['JV', 'JAV'], // JAVANESE
+        ['', 'JBO'], // LOJBAN
+        ['JA', 'JPN'], // JAPANESE
+        ['', 'JPR'], // JUDEO-PERSIAN
+        ['', 'JRB'], // JUDEO-ARABIC
+        ['', 'KAA'], // KARA-KALPAK
+        ['', 'KAB'], // KABYLE
+        ['', 'KAC'], // KACHIN; JINGPHO
+        ['KL', 'KAL'], // KALAALLISUT; GREENLANDIC
+        ['', 'KAM'], // KAMBA
+        ['KN', 'KAN'], // KANNADA
+        ['', 'KAR'], // KAREN LANGUAGES
+        ['KS', 'KAS'], // KASHMIRI
+        ['KR', 'KAU'], // KANURI
+        ['', 'KAW'], // KAWI
+        ['KK', 'KAZ'], // KAZAKH
+        ['', 'KBD'], // KABARDIAN
+        ['', 'KHA'], // KHASI
+        ['', 'KHI'], // KHOISAN LANGUAGES
+        ['KM', 'KHM'], // CENTRAL KHMER
+        ['', 'KHO'], // KHOTANESE; SAKAN
+        ['KI', 'KIK'], // KIKUYU; GIKUYU
+        ['RW', 'KIN'], // KINYARWANDA
+        ['KY', 'KIR'], // KIRGHIZ; KYRGYZ
+        ['', 'KMB'], // KIMBUNDU
+        ['', 'KOK'], // KONKANI
+        ['KV', 'KOM'], // KOMI
+        ['KG', 'KON'], // KONGO
+        ['KO', 'KOR'], // KOREAN
+        ['', 'KOS'], // KOSRAEAN
+        ['', 'KPE'], // KPELLE
+        ['', 'KRC'], // KARACHAY-BALKAR
+        ['', 'KRL'], // KARELIAN
+        ['', 'KRO'], // KRU LANGUAGES
+        ['', 'KRU'], // KURUKH
+        ['KJ', 'KUA'], // KUANYAMA; KWANYAMA
+        ['', 'KUM'], // KUMYK
+        ['KU', 'KUR'], // KURDISH
+        ['', 'KUT'], // KUTENAI
+        ['', 'LAD'], // LADINO
+        ['', 'LAH'], // LAHNDA
+        ['', 'LAM'], // LAMBA
+        ['LO', 'LAO'], // LAO
+        ['LA', 'LAT'], // LATIN
+        ['LV', 'LAV'], // LATVIAN
+        ['', 'LEZ'], // LEZGHIAN
+        ['LI', 'LIM'], // LIMBURGAN; LIMBURGER; LIMBURGISH
+        ['LN', 'LIN'], // LINGALA
+        ['LT', 'LIT'], // LITHUANIAN
+        ['', 'LOL'], // MONGO
+        ['', 'LOZ'], // LOZI
+        ['LB', 'LTZ'], // LUXEMBOURGISH; LETZEBURGESCH
+        ['', 'LUA'], // LUBA-LULUA
+        ['LU', 'LUB'], // LUBA-KATANGA
+        ['LG', 'LUG'], // GANDA
+        ['', 'LUI'], // LUISENO
+        ['', 'LUN'], // LUNDA
+        ['', 'LUO'], // LUO (KENYA AND TANZANIA)
+        ['', 'LUS'], // LUSHAI
+        ['MK', 'MAC'], // MACEDONIAN
+        ['', 'MAD'], // MADURESE
+        ['', 'MAG'], // MAGAHI
+        ['MH', 'MAH'], // MARSHALLESE
+        ['', 'MAI'], // MAITHILI
+        ['', 'MAK'], // MAKASAR
+        ['ML', 'MAL'], // MALAYALAM
+        ['', 'MAN'], // MANDINGO
+        ['MI', 'MAO'], // MAORI
+        ['', 'MAP'], // AUSTRONESIAN LANGUAGES
+        ['MR', 'MAR'], // MARATHI
+        ['', 'MAS'], // MASAI
+        ['MS', 'MAY'], // MALAY
+        ['', 'MDF'], // MOKSHA
+        ['', 'MDR'], // MANDAR
+        ['', 'MEN'], // MENDE
+        ['', 'MGA'], // IRISH, MIDDLE (900-1200)
+        ['', 'MIC'], // MI'KMAQ; MICMAC
+        ['', 'MIN'], // MINANGKABAU
+        ['', 'MIS'], // UNCODED LANGUAGES
+        ['', 'MKH'], // MON-KHMER LANGUAGES
+        ['MG', 'MLG'], // MALAGASY
+        ['MT', 'MLT'], // MALTESE
+        ['', 'MNC'], // MANCHU
+        ['', 'MNI'], // MANIPURI
+        ['', 'MNO'], // MANOBO LANGUAGES
+        ['', 'MOH'], // MOHAWK
+        ['MN', 'MON'], // MONGOLIAN
+        ['', 'MOS'], // MOSSI
+        ['', 'MUL'], // MULTIPLE LANGUAGES
+        ['', 'MUN'], // MUNDA LANGUAGES
+        ['', 'MUS'], // CREEK
+        ['', 'MWL'], // MIRANDESE
+        ['', 'MWR'], // MARWARI
+        ['', 'MYN'], // MAYAN LANGUAGES
+        ['', 'MYV'], // ERZYA
+        ['', 'NAH'], // NAHUATL LANGUAGES
+        ['', 'NAI'], // NORTH AMERICAN INDIAN LANGUAGES
+        ['', 'NAP'], // NEAPOLITAN
+        ['NA', 'NAU'], // NAURU
+        ['NV', 'NAV'], // NAVAJO; NAVAHO
+        ['NR', 'NBL'], // NDEBELE, SOUTH; SOUTH NDEBELE
+        ['ND', 'NDE'], // NDEBELE, NORTH; NORTH NDEBELE
+        ['NG', 'NDO'], // NDONGA
+        ['', 'NDS'], // LOW GERMAN; LOW SAXON; GERMAN, LOW; SAXON, LOW
+        ['NE', 'NEP'], // NEPALI
+        ['', 'NEW'], // NEPAL BHASA; NEWARI
+        ['', 'NIA'], // NIAS
+        ['', 'NIC'], // NIGER-KORDOFANIAN LANGUAGES
+        ['', 'NIU'], // NIUEAN
+        ['NN', 'NNO'], // NORWEGIAN NYNORSK; NYNORSK, NORWEGIAN
+        ['NB', 'NOB'], // BOKMÅL, NORWEGIAN; NORWEGIAN BOKMÅL
+        ['', 'NOG'], // NOGAI
+        ['', 'NON'], // NORSE, OLD
+        ['NO', 'NOR'], // NORWEGIAN
+        ['', 'NQO'], // N'KO
+        ['', 'NSO'], // PEDI; SEPEDI; NORTHERN SOTHO
+        ['', 'NUB'], // NUBIAN LANGUAGES
+        ['', 'NWC'], // CLASSICAL NEWARI; OLD NEWARI; CLASSICAL NEPAL BHASA
+        ['NY', 'NYA'], // CHICHEWA; CHEWA; NYANJA
+        ['', 'NYM'], // NYAMWEZI
+        ['', 'NYN'], // NYANKOLE
+        ['', 'NYO'], // NYORO
+        ['', 'NZI'], // NZIMA
+        ['OC', 'OCI'], // OCCITAN (POST 1500); PROVENÇAL
+        ['OJ', 'OJI'], // OJIBWA
+        ['OR', 'ORI'], // ORIYA
+        ['OM', 'ORM'], // OROMO
+        ['', 'OSA'], // OSAGE
+        ['OS', 'OSS'], // OSSETIAN; OSSETIC
+        ['', 'OTA'], // TURKISH, OTTOMAN (1500-1928)
+        ['', 'OTO'], // OTOMIAN LANGUAGES
+        ['', 'PAA'], // PAPUAN LANGUAGES
+        ['', 'PAG'], // PANGASINAN
+        ['', 'PAL'], // PAHLAVI
+        ['', 'PAM'], // PAMPANGA; KAPAMPANGAN
+        ['PA', 'PAN'], // PANJABI; PUNJABI
+        ['', 'PAP'], // PAPIAMENTO
+        ['', 'PAU'], // PALAUAN
+        ['', 'PEO'], // PERSIAN, OLD (CA.600-400 B.C.)
+        ['FA', 'PER'], // PERSIAN
+        ['', 'PHI'], // PHILIPPINE LANGUAGES
+        ['', 'PHN'], // PHOENICIAN
+        ['PI', 'PLI'], // PALI
+        ['PL', 'POL'], // POLISH
+        ['', 'PON'], // POHNPEIAN
+        ['PT', 'POR'], // PORTUGUESE
+        ['', 'PRA'], // PRAKRIT LANGUAGES
+        ['', 'PRO'], // PROVENÇAL, OLD (TO 1500)
+        ['PS', 'PUS'], // PUSHTO; PASHTO
+        ['', 'QAA-QTZ'], // RESERVED FOR LOCAL USE
+        ['QU', 'QUE'], // QUECHUA
+        ['', 'RAJ'], // RAJASTHANI
+        ['', 'RAP'], // RAPANUI
+        ['', 'RAR'], // RAROTONGAN; COOK ISLANDS MAORI
+        ['', 'ROA'], // ROMANCE LANGUAGES
+        ['RM', 'ROH'], // ROMANSH
+        ['', 'ROM'], // ROMANY
+        ['RO', 'RUM'], // ROMANIAN; MOLDAVIAN; MOLDOVAN
+        ['RN', 'RUN'], // RUNDI
+        ['', 'RUP'], // AROMANIAN; ARUMANIAN; MACEDO-ROMANIAN
+        ['RU', 'RUS'], // RUSSIAN
+        ['', 'SAD'], // SANDAWE
+        ['SG', 'SAG'], // SANGO
+        ['', 'SAH'], // YAKUT
+        ['', 'SAI'], // SOUTH AMERICAN INDIAN (OTHER)
+        ['', 'SAL'], // SALISHAN LANGUAGES
+        ['', 'SAM'], // SAMARITAN ARAMAIC
+        ['SA', 'SAN'], // SANSKRIT
+        ['', 'SAS'], // SASAK
+        ['', 'SAT'], // SANTALI
+        ['', 'SCN'], // SICILIAN
+        ['', 'SCO'], // SCOTS
+        ['', 'SEL'], // SELKUP
+        ['', 'SEM'], // SEMITIC LANGUAGES
+        ['', 'SGA'], // IRISH, OLD (TO 900)
+        ['', 'SGN'], // SIGN LANGUAGES
+        ['', 'SHN'], // SHAN
+        ['', 'SID'], // SIDAMO
+        ['SI', 'SIN'], // SINHALA; SINHALESE
+        ['', 'SIO'], // SIOUAN LANGUAGES
+        ['', 'SIT'], // SINO-TIBETAN LANGUAGES
+        ['', 'SLA'], // SLAVIC LANGUAGES
+        ['SK', 'SLO'], // SLOVAK
+        ['SL', 'SLV'], // SLOVENIAN
+        ['', 'SMA'], // SOUTHERN SAMI
+        ['SE', 'SME'], // NORTHERN SAMI
+        ['', 'SMI'], // SAMI LANGUAGES
+        ['', 'SMJ'], // LULE SAMI
+        ['', 'SMN'], // INARI SAMI
+        ['SM', 'SMO'], // SAMOAN
+        ['', 'SMS'], // SKOLT SAMI
+        ['SN', 'SNA'], // SHONA
+        ['SD', 'SND'], // SINDHI
+        ['', 'SNK'], // SONINKE
+        ['', 'SOG'], // SOGDIAN
+        ['SO', 'SOM'], // SOMALI
+        ['', 'SON'], // SONGHAI LANGUAGES
+        ['ST', 'SOT'], // SOTHO, SOUTHERN
+        ['ES', 'SPA'], // SPANISH; CASTILIAN
+        ['SC', 'SRD'], // SARDINIAN
+        ['', 'SRN'], // SRANAN TONGO
+        ['SR', 'SRP'], // SERBIAN
+        ['', 'SRR'], // SERER
+        ['', 'SSA'], // NILO-SAHARAN LANGUAGES
+        ['SS', 'SSW'], // SWATI
+        ['', 'SUK'], // SUKUMA
+        ['SU', 'SUN'], // SUNDANESE
+        ['', 'SUS'], // SUSU
+        ['', 'SUX'], // SUMERIAN
+        ['SW', 'SWA'], // SWAHILI
+        ['SV', 'SWE'], // SWEDISH
+        ['', 'SYC'], // CLASSICAL SYRIAC
+        ['', 'SYR'], // SYRIAC
+        ['TY', 'TAH'], // TAHITIAN
+        ['', 'TAI'], // TAI LANGUAGES
+        ['TA', 'TAM'], // TAMIL
+        ['TT', 'TAT'], // TATAR
+        ['TE', 'TEL'], // TELUGU
+        ['', 'TEM'], // TIMNE
+        ['', 'TER'], // TERENO
+        ['', 'TET'], // TETUM
+        ['TG', 'TGK'], // TAJIK
+        ['TL', 'TGL'], // TAGALOG
+        ['TH', 'THA'], // THAI
+        ['BO', 'TIB'], // TIBETAN
+        ['', 'TIG'], // TIGRE
+        ['TI', 'TIR'], // TIGRINYA
+        ['', 'TIV'], // TIV
+        ['', 'TKL'], // TOKELAU
+        ['', 'TLH'], // KLINGON; TLHINGAN-HOL
+        ['', 'TLI'], // TLINGIT
+        ['', 'TMH'], // TAMASHEK
+        ['', 'TOG'], // TONGA (NYASA)
+        ['TO', 'TON'], // TONGA (TONGA ISLANDS)
+        ['', 'TPI'], // TOK PISIN
+        ['', 'TSI'], // TSIMSHIAN
+        ['TN', 'TSN'], // TSWANA
+        ['TS', 'TSO'], // TSONGA
+        ['TK', 'TUK'], // TURKMEN
+        ['', 'TUM'], // TUMBUKA
+        ['', 'TUP'], // TUPI LANGUAGES
+        ['TR', 'TUR'], // TURKISH
+        ['', 'TUT'], // ALTAIC LANGUAGES
+        ['', 'TVL'], // TUVALU
+        ['TW', 'TWI'], // TWI
+        ['', 'TYV'], // TUVINIAN
+        ['', 'UDM'], // UDMURT
+        ['', 'UGA'], // UGARITIC
+        ['UG', 'UIG'], // UIGHUR; UYGHUR
+        ['UK', 'UKR'], // UKRAINIAN
+        ['', 'UMB'], // UMBUNDU
+        ['', 'UND'], // UNDETERMINED
+        ['UR', 'URD'], // URDU
+        ['UZ', 'UZB'], // UZBEK
+        ['', 'VAI'], // VAI
+        ['VE', 'VEN'], // VENDA
+        ['VI', 'VIE'], // VIETNAMESE
+        ['VO', 'VOL'], // VOLAPÜK
+        ['', 'VOT'], // VOTIC
+        ['', 'WAK'], // WAKASHAN LANGUAGES
+        ['', 'WAL'], // WALAMO
+        ['', 'WAR'], // WARAY
+        ['', 'WAS'], // WASHO
+        ['CY', 'WEL'], // WELSH
+        ['', 'WEN'], // SORBIAN LANGUAGES
+        ['WA', 'WLN'], // WALLOON
+        ['WO', 'WOL'], // WOLOF
+        ['', 'XAL'], // KALMYK; OIRAT
+        ['XH', 'XHO'], // XHOSA
+        ['', 'YAO'], // YAO
+        ['', 'YAP'], // YAPESE
+        ['YI', 'YID'], // YIDDISH
+        ['YO', 'YOR'], // YORUBA
+        ['', 'YPK'], // YUPIK LANGUAGES
+        ['', 'ZAP'], // ZAPOTEC
+        ['', 'ZBL'], // BLISSYMBOLS; BLISSYMBOLICS; BLISS
+        ['', 'ZEN'], // ZENAGA
+        ['', 'ZGH'], // STANDARD MOROCCAN TAMAZIGHT
+        ['ZA', 'ZHA'], // ZHUANG; CHUANG
+        ['', 'ZND'], // ZANDE LANGUAGES
+        ['ZU', 'ZUL'], // ZULU
+        ['', 'ZUN'], // ZUNI
+        ['', 'ZXX'], // NO LINGUISTIC CONTENT; NOT APPLICABLE
+        ['', 'ZZA'], // ZAZA; DIMILI; DIMLI; KIRDKI; KIRMANJKI; ZAZAKI
+    ];
+
+    public $set;
+    public $index;
+
+    public function __construct($set = self::ALPHA2)
+    {
+        $index = array_search($set, self::getAvailableSets(), true);
+
+        if (false === $index) {
+            throw new ComponentException(sprintf('"%s" is not a valid language set for ISO 639', $set));
+        }
+
+        $this->set = $set;
+        $this->index = $index;
+    }
+
+    public static function getAvailableSets()
+    {
+        return [
+            self::ALPHA2,
+            self::ALPHA3,
+        ];
+    }
+
+    private function getLanguageCodeList($index)
+    {
+        $languageList = [];
+
+        foreach ($this->languageCodeList as $language) {
+            $languageList[] = $language[$index];
+        }
+
+        return $languageList;
+    }
+
+    public function validate($input)
+    {
+        if (!is_string($input) || '' === $input) {
+            return false;
+        }
+
+        return in_array(
+            strtoupper($input),
+            $this->getLanguageCodeList($this->index),
+            true
+        );
+    }
+}

library/Validator.php

@@ -82,6 +82,7 @@ use Respect\Validation\Rules\Key;
  * @method static Validator keyNested(string $reference, Validatable $referenceValidator = null, bool $mandatory = true)
  * @method static Validator keySet(Key $rule...)
  * @method static Validator keyValue(string $comparedKey, string $ruleName, string $baseKey)
+ * @method static Validator languageCode(string $set)
  * @method static Validator leapDate(string $format)
  * @method static Validator leapYear()
  * @method static Validator length(int $min = null, int $max = null, bool $inclusive = true)

tests/integration/rules/languagecode_1.phpt

@@ -0,0 +1,24 @@
+--FILE--
+<?php
+require 'vendor/autoload.php';
+
+use Respect\Validation\Validator as v;
+use Respect\Validation\Rules\LanguageCode;
+
+v::languageCode()->assert('pt');
+v::languageCode()->assert('en');
+v::languageCode()->assert('it');
+
+v::languageCode()->check('pt');
+v::languageCode()->check('en');
+v::languageCode()->check('it');
+
+v::languageCode('alpha-3')->assert('por');
+v::languageCode('alpha-3')->assert('eng');
+v::languageCode('alpha-3')->assert('ita');
+
+v::languageCode('alpha-3')->check('por');
+v::languageCode('alpha-3')->check('eng');
+v::languageCode('alpha-3')->check('ita');
+?>
+--EXPECTF--

tests/integration/rules/languagecode_2.phpt

@@ -0,0 +1,38 @@
+--FILE--
+<?php
+require 'vendor/autoload.php';
+
+use Respect\Validation\Validator as v;
+use Respect\Validation\Exceptions\LanguageCodeException;
+use Respect\Validation\Exceptions\AllOfException;
+
+try {
+    v::languageCode('alpha-3')->check('pt');
+} catch (LanguageCodeException $e) {
+    echo $e->getMainMessage() . PHP_EOL;
+}
+
+try {
+    v::languageCode()->assert('eng');
+} catch (AllOfException $e) {
+    echo $e->getFullMessage() . PHP_EOL;
+}
+
+try {
+    v::not(v::languageCode())->assert('en');
+} catch (AllOfException $e) {
+    echo $e->getFullMessage() . PHP_EOL;
+}
+
+try {
+    v::not(v::languageCode())->check('pt');
+} catch (LanguageCodeException $e) {
+    echo $e->getMainMessage() . PHP_EOL;
+}
+
+?>
+--EXPECTF--
+"pt" must be a valid language
+- "eng" must be a valid language
+- "en" must not be a valid language
+"pt" must not be a valid language

tests/unit/Rules/LanguageCodeTest.php

@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of Respect/Validation.
+ *
+ * (c) Alexandre Gomes Gaigalas <alexandre@gaigalas.net>
+ *
+ * For the full copyright and license information, please view the "LICENSE.md"
+ * file that was distributed with this source code.
+ */
+
+namespace Respect\Validation\Rules;
+
+/**
+ * @group  rule
+ * @covers Respect\Validation\Rules\LanguageCode
+ */
+class LanguageCodeTest extends RuleTestCase
+{
+    public function providerForValidInput()
+    {
+        $ruleAlpha2 = new LanguageCode();
+        $ruleAlpha3 = new LanguageCode('alpha-3');
+
+        return [
+            [$ruleAlpha2, 'pt'],
+            [$ruleAlpha3, 'por'],
+            [$ruleAlpha2, 'en'],
+            [$ruleAlpha3, 'eng'],
+            [$ruleAlpha2, 'it'],
+            [$ruleAlpha3, 'ita'],
+            [$ruleAlpha2, 'la'],
+            [$ruleAlpha3, 'lat'],
+        ];
+    }
+
+    public function providerForInvalidInput()
+    {
+        $ruleAlpha2 = new LanguageCode();
+        $ruleAlpha3 = new LanguageCode('alpha-3');
+
+        return [
+            [$ruleAlpha2, 'por'],
+            [$ruleAlpha2, ''],
+            [$ruleAlpha2, null],
+            [$ruleAlpha2, false],
+            [$ruleAlpha2, []],
+            [$ruleAlpha3, 'pt'],
+        ];
+    }
+}