igp_hashtags.php

<?php

/**
	 * Get matching hashtag regex.
	 * Based on https://github.com/ngnpope/twitter-text-php
	 *
	 * @return string Regex pattern.
	 */
	protected function valid_hashtag_regex() {
		$tmp = array();
		// Expression to match latin accented characters.
		//
		// 0x00C0-0x00D6
		// 0x00D8-0x00F6
		// 0x00F8-0x00FF
		// 0x0100-0x024f
		// 0x0253-0x0254
		// 0x0256-0x0257
		// 0x0259
		// 0x025b
		// 0x0263
		// 0x0268
		// 0x026f
		// 0x0272
		// 0x0289
		// 0x028b
		// 0x02bb
		// 0x0300-0x036f
		// 0x1e00-0x1eff
		//
		// Excludes 0x00D7 - multiplication sign (confusable with 'x').
		// Excludes 0x00F7 - division sign.
		$tmp['latin_accents'] = '\x{00c0}-\x{00d6}\x{00d8}-\x{00f6}\x{00f8}-\x{00ff}';
		$tmp['latin_accents'] .= '\x{0100}-\x{024f}\x{0253}-\x{0254}\x{0256}-\x{0257}';
		$tmp['latin_accents'] .= '\x{0259}\x{025b}\x{0263}\x{0268}\x{026f}\x{0272}\x{0289}\x{028b}\x{02bb}\x{0300}-\x{036f}\x{1e00}-\x{1eff}';
		// Expression to match non-latin characters.
		//
		// Cyrillic (Russian, Ukranian, ...):
		//
		// 0x0400-0x04FF Cyrillic
		// 0x0500-0x0527 Cyrillic Supplement
		// 0x2DE0-0x2DFF Cyrillic Extended A
		// 0xA640-0xA69F Cyrillic Extended B
		$tmp['non_latin_hashtag_chars'] = '\x{0400}-\x{04ff}\x{0500}-\x{0527}\x{2de0}-\x{2dff}\x{a640}-\x{a69f}';
		// Hebrew:
		//
		// 0x0591-0x05bf Hebrew
		// 0x05c1-0x05c2
		// 0x05c4-0x05c5
		// 0x05c7
		// 0x05d0-0x05ea
		// 0x05f0-0x05f4
		// 0xfb12-0xfb28 Hebrew Presentation Forms
		// 0xfb2a-0xfb36
		// 0xfb38-0xfb3c
		// 0xfb3e
		// 0xfb40-0xfb41
		// 0xfb43-0xfb44
		// 0xfb46-0xfb4f
		$tmp['non_latin_hashtag_chars'] .= '\x{0591}-\x{05bf}\x{05c1}-\x{05c2}\x{05c4}-\x{05c5}\x{05c7}\x{05d0}-\x{05ea}\x{05f0}-\x{05f4}';
		$tmp['non_latin_hashtag_chars'] .= '\x{fb12}-\x{fb28}\x{fb2a}-\x{fb36}\x{fb38}-\x{fb3c}\x{fb3e}\x{fb40}-\x{fb41}\x{fb43}-\x{fb44}\x{fb46}-\x{fb4f}';
		// Arabic:
		//
		// 0x0610-0x061a Arabic
		// 0x0620-0x065f
		// 0x066e-0x06d3
		// 0x06d5-0x06dc
		// 0x06de-0x06e8
		// 0x06ea-0x06ef
		// 0x06fa-0x06fc
		// 0x06ff
		// 0x0750-0x077f Arabic Supplement
		// 0x08a0        Arabic Extended A
		// 0x08a2-0x08ac
		// 0x08e4-0x08fe
		// 0xfb50-0xfbb1 Arabic Pres. Forms A
		// 0xfbd3-0xfd3d
		// 0xfd50-0xfd8f
		// 0xfd92-0xfdc7
		// 0xfdf0-0xfdfb
		// 0xfe70-0xfe74 Arabic Pres. Forms B
		// 0xfe76-0xfefc
		$tmp['non_latin_hashtag_chars'] .= '\x{0610}-\x{061a}\x{0620}-\x{065f}\x{066e}-\x{06d3}\x{06d5}-\x{06dc}\x{06de}-\x{06e8}\x{06ea}-\x{06ef}\x{06fa}-\x{06fc}\x{06ff}';
		$tmp['non_latin_hashtag_chars'] .= '\x{0750}-\x{077f}\x{08a0}\x{08a2}-\x{08ac}\x{08e4}-\x{08fe}';
		$tmp['non_latin_hashtag_chars'] .= '\x{fb50}-\x{fbb1}\x{fbd3}-\x{fd3d}\x{fd50}-\x{fd8f}\x{fd92}-\x{fdc7}\x{fdf0}-\x{fdfb}\x{fe70}-\x{fe74}\x{fe76}-\x{fefc}';
		//
		// 0x200c-0x200c Zero-Width Non-Joiner
		// 0x0e01-0x0e3a Thai
		$tmp['non_latin_hashtag_chars'] .= '\x{200c}\x{0e01}-\x{0e3a}';
		// Hangul (Korean):
		//
		// 0x0e40-0x0e4e Hangul (Korean)
		// 0x1100-0x11FF Hangul Jamo
		// 0x3130-0x3185 Hangul Compatibility Jamo
		// 0xA960-0xA97F Hangul Jamo Extended A
		// 0xAC00-0xD7AF Hangul Syllables
		// 0xD7B0-0xD7FF Hangul Jamo Extended B
		// 0xFFA1-0xFFDC Half-Width Hangul
		$tmp['non_latin_hashtag_chars'] .= '\x{0e40}-\x{0e4e}\x{1100}-\x{11ff}\x{3130}-\x{3185}\x{a960}-\x{a97f}\x{ac00}-\x{d7af}\x{d7b0}-\x{d7ff}\x{ffa1}-\x{ffdc}';
		// Expression to match other characters.
		//
		// 0x30A1-0x30FA   Katakana (Full-Width)
		// 0x30FC-0x30FE   Katakana (Full-Width)
		// 0xFF66-0xFF9F   Katakana (Half-Width)
		// 0xFF10-0xFF19   Latin (Full-Width)
		// 0xFF21-0xFF3A   Latin (Full-Width)
		// 0xFF41-0xFF5A   Latin (Full-Width)
		// 0x3041-0x3096   Hiragana
		// 0x3099-0x309E   Hiragana
		// 0x3400-0x4DBF   Kanji (CJK Extension A)
		// 0x4E00-0x9FFF   Kanji (Unified)
		// 0x20000-0x2A6DF Kanji (CJK Extension B)
		// 0x2A700-0x2B73F Kanji (CJK Extension C)
		// 0x2B740-0x2B81F Kanji (CJK Extension D)
		// 0x2F800-0x2FA1F Kanji (CJK supplement)
		// 0x3003          Kanji (CJK supplement)
		// 0x3005          Kanji (CJK supplement)
		// 0x303B          Kanji (CJK supplement)
		$tmp['cj_hashtag_characters'] = '\x{30A1}-\x{30FA}\x{30FC}-\x{30FE}\x{FF66}-\x{FF9F}\x{FF10}-\x{FF19}\x{FF21}-\x{FF3A}\x{FF41}-\x{FF5A}\x{3041}-\x{3096}\x{3099}-\x{309E}\x{3400}-\x{4DBF}\x{4E00}-\x{9FFF}\x{3003}\x{3005}\x{303B}\x{020000}-\x{02a6df}\x{02a700}-\x{02b73f}\x{02b740}-\x{02b81f}\x{02f800}-\x{02fa1f}';

		$tmp['hashtag_alpha']        = '[a-z_' . $tmp['latin_accents'] . $tmp['non_latin_hashtag_chars'] . $tmp['cj_hashtag_characters'] . ']';
		$tmp['hashtag_alphanumeric'] = '[a-z0-9_' . $tmp['latin_accents'] . $tmp['non_latin_hashtag_chars'] . $tmp['cj_hashtag_characters'] . ']';
		$tmp['hashtag_boundary']     = '(?:\A|\z|[^&a-z0-9_' . $tmp['latin_accents'] . $tmp['non_latin_hashtag_chars'] . $tmp['cj_hashtag_characters'] . '])';

		$tmp['hashtag'] = '(' . $tmp['hashtag_boundary'] . ')(' . $tmp['hashtag_alphanumeric'] . '*' . $tmp['hashtag_alpha'] . $tmp['hashtag_alphanumeric'] . '*)';

		$valid_hashtag = '/' . $tmp['hashtag'] . '(?=(.*|$))/iu';

		return $valid_hashtag;
	}