<?php
/*
	Question2Answer (c) Gideon Greenspan
	http://www.question2answer.org/
	License: GPLv2+ <http://www.question2answer.org/license.php>

	File: qa-include/Util/String.php
	Description: Some useful string-related stuff
*/

class Q2A_Util_String
{
	/**
	 * Notable exclusions here: $ & - _ # % @
	 */
	private static $pregIndexWordSeparator = '[\n\r\t\ \!\"\\\'\(\)\*\+\,\.\/\:\;\<\=\>\?\[\\\\\]\^\`\{\|\}\~]';

	/**
	 * Asterisk (*) excluded here because it's used to match anything
	 */
	private static $pregBlockWordSeparator = '[\n\r\t\ \!\"\\\'\(\)\+\,\.\/\:\;\<\=\>\?\[\\\\\]\^\`\{\|\}\~\$\&\-\_\#\%\@]';

	/**
	 * Pattern to match Chinese/Japanese/Korean ideographic symbols in UTF-8 encoding
	 */
	private static $pregCjkIdeographsUtf8 = '\xE2[\xBA-\xBF][\x80-\xBF]|\xE3[\x80\x88-\xBF][\x80-\xBF]|[\xE4-\xE9][\x80-\xBF][\x80-\xBF]|\xEF[\xA4-\xAB][\x80-\xBF]|\xF0[\xA0-\xAF][\x80-\xBF][\x80-\xBF]';

	/**
	 * Holder for keep-length data
	 */
	private static $utf8PunctuationKeepLength = array();

	/**
	 * Converts UTF-8 punctuation characters to spaces (or in some cases, hyphens)
	 */
	private static $utf8Punctuation = array(
		"\xC2\xA1" => ' ', // INVERTED EXCLAMATION MARK
		"\xC2\xA6" => ' ', // BROKEN BAR
		"\xC2\xAB" => ' ', // LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
		"\xC2\xB1" => ' ', // PLUS-MINUS SIGN
		"\xC2\xBB" => ' ', // RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
		"\xC2\xBF" => ' ', // INVERTED QUESTION MARK
		"\xC3\x97" => ' ', // MULTIPLICATION SIGN
		"\xC3\xB7" => ' ', // DIVISION SIGN

		"\xE2\x80\x80" => ' ', // EN QUAD
		"\xE2\x80\x81" => ' ', // EM QUAD
		"\xE2\x80\x82" => ' ', // EN SPACE
		"\xE2\x80\x83" => ' ', // EM SPACE
		"\xE2\x80\x84" => ' ', // THREE-PER-EM SPACE
		"\xE2\x80\x85" => ' ', // FOUR-PER-EM SPACE
		"\xE2\x80\x86" => ' ', // SIX-PER-EM SPACE
		"\xE2\x80\x87" => ' ', // FIGURE SPACE
		"\xE2\x80\x88" => ' ', // PUNCTUATION SPACE
		"\xE2\x80\x89" => ' ', // THIN SPACE
		"\xE2\x80\x8A" => ' ', // HAIR SPACE
		"\xE2\x80\x8B" => ' ', // ZERO WIDTH SPACE
		"\xE2\x80\x8C" => ' ', // ZERO WIDTH NON-JOINER
		"\xE2\x80\x8E" => ' ', // LEFT-TO-RIGHT MARK
		"\xE2\x80\x8F" => ' ', // RIGHT-TO-LEFT MARK

		"\xE2\x80\x90" => '-', // HYPHEN
		"\xE2\x80\x91" => '-', // NON-BREAKING HYPHEN
		"\xE2\x80\x92" => '-', // FIGURE DASH
		"\xE2\x80\x93" => '-', // EN DASH
		"\xE2\x80\x94" => '-', // EM DASH
		"\xE2\x80\x95" => '-', // HORIZONTAL BAR

		"\xE2\x80\x96" => ' ', // DOUBLE VERTICAL LINE
		"\xE2\x80\x98" => ' ', // LEFT SINGLE QUOTATION MARK
		"\xE2\x80\x99" => "'", // RIGHT SINGLE QUOTATION MARK
		"\xE2\x80\x9A" => ' ', // SINGLE LOW-9 QUOTATION MARK
		"\xE2\x80\x9B" => ' ', // SINGLE HIGH-REVERSED-9 QUOTATION MARK
		"\xE2\x80\x9C" => ' ', // LEFT DOUBLE QUOTATION MARK
		"\xE2\x80\x9D" => ' ', // RIGHT DOUBLE QUOTATION MARK
		"\xE2\x80\x9E" => ' ', // DOUBLE LOW-9 QUOTATION MARK
		"\xE2\x80\x9F" => ' ', // DOUBLE HIGH-REVERSED-9 QUOTATION MARK

		"\xE2\x80\xA2" => ' ', // BULLET
		"\xE2\x80\xA4" => ' ', // ONE DOT LEADER
		"\xE2\x80\xA5" => ' ', // TWO DOT LEADER
		"\xE2\x80\xA6" => ' ', // HORIZONTAL ELLIPSIS
		"\xE2\x80\xB9" => ' ', // SINGLE LEFT-POINTING ANGLE QUOTATION MARK
		"\xE2\x80\xBA" => ' ', // SINGLE RIGHT-POINTING ANGLE QUOTATION MARK
		"\xE2\x80\xBC" => ' ', // DOUBLE EXCLAMATION MARK
		"\xE2\x80\xBD" => ' ', // INTERROBANG
		"\xE2\x81\x87" => ' ', // DOUBLE QUESTION MARK
		"\xE2\x81\x88" => ' ', // QUESTION EXCLAMATION MARK
		"\xE2\x81\x89" => ' ', // EXCLAMATION QUESTION MARK

		"\xE3\x80\x80" => ' ', // IDEOGRAPHIC SPACE
		"\xE3\x80\x81" => ' ', // IDEOGRAPHIC COMMA
		"\xE3\x80\x82" => ' ', // IDEOGRAPHIC FULL STOP
	);

	/**
	 * Convert UTF-8 accented characters to basic Roman characters
	 */
	private static $utf8RemoveAccents = array(
		"\xC3\x80" => 'A', // LATIN CAPITAL LETTER A WITH GRAVE
		"\xC3\x81" => 'A', // LATIN CAPITAL LETTER A WITH ACUTE
		"\xC3\x82" => 'A', // LATIN CAPITAL LETTER A WITH CIRCUMFLEX
		"\xC3\x83" => 'A', // LATIN CAPITAL LETTER A WITH TILDE
		"\xC3\x84" => 'A', // LATIN CAPITAL LETTER A WITH DIAERESIS
		"\xC3\x85" => 'A', // LATIN CAPITAL LETTER A WITH RING ABOVE
		"\xC3\x86" => 'AE', // LATIN CAPITAL LETTER AE
		"\xC3\x87" => 'C', // LATIN CAPITAL LETTER C WITH CEDILLA
		"\xC3\x88" => 'E', // LATIN CAPITAL LETTER E WITH GRAVE
		"\xC3\x89" => 'E', // LATIN CAPITAL LETTER E WITH ACUTE
		"\xC3\x8A" => 'E', // LATIN CAPITAL LETTER E WITH CIRCUMFLEX
		"\xC3\x8B" => 'E', // LATIN CAPITAL LETTER E WITH DIAERESIS
		"\xC3\x8C" => 'I', // LATIN CAPITAL LETTER I WITH GRAVE
		"\xC3\x8D" => 'I', // LATIN CAPITAL LETTER I WITH ACUTE
		"\xC3\x8E" => 'I', // LATIN CAPITAL LETTER I WITH CIRCUMFLEX
		"\xC3\x8F" => 'I', // LATIN CAPITAL LETTER I WITH DIAERESIS
		"\xC3\x91" => 'N', // LATIN CAPITAL LETTER N WITH TILDE
		"\xC3\x92" => 'O', // LATIN CAPITAL LETTER O WITH GRAVE
		"\xC3\x93" => 'O', // LATIN CAPITAL LETTER O WITH ACUTE
		"\xC3\x94" => 'O', // LATIN CAPITAL LETTER O WITH CIRCUMFLEX
		"\xC3\x95" => 'O', // LATIN CAPITAL LETTER O WITH TILDE
		"\xC3\x96" => 'O', // LATIN CAPITAL LETTER O WITH DIAERESIS
		"\xC3\x98" => 'O', // LATIN CAPITAL LETTER O WITH STROKE
		"\xC3\x99" => 'U', // LATIN CAPITAL LETTER U WITH GRAVE
		"\xC3\x9A" => 'U', // LATIN CAPITAL LETTER U WITH ACUTE
		"\xC3\x9B" => 'U', // LATIN CAPITAL LETTER U WITH CIRCUMFLEX
		"\xC3\x9C" => 'U', // LATIN CAPITAL LETTER U WITH DIAERESIS
		"\xC3\x9D" => 'Y', // LATIN CAPITAL LETTER Y WITH ACUTE
		"\xC3\x9F" => 'ss', // LATIN SMALL LETTER SHARP S
		"\xC3\xA0" => 'a', // LATIN SMALL LETTER A WITH GRAVE
		"\xC3\xA1" => 'a', // LATIN SMALL LETTER A WITH ACUTE
		"\xC3\xA2" => 'a', // LATIN SMALL LETTER A WITH CIRCUMFLEX
		"\xC3\xA3" => 'a', // LATIN SMALL LETTER A WITH TILDE
		"\xC3\xA4" => 'a', // LATIN SMALL LETTER A WITH DIAERESIS
		"\xC3\xA5" => 'a', // LATIN SMALL LETTER A WITH RING ABOVE
		"\xC3\xA6" => 'ae', // LATIN SMALL LETTER AE
		"\xC3\xA7" => 'c', // LATIN SMALL LETTER C WITH CEDILLA
		"\xC3\xA8" => 'e', // LATIN SMALL LETTER E WITH GRAVE
		"\xC3\xA9" => 'e', // LATIN SMALL LETTER E WITH ACUTE
		"\xC3\xAA" => 'e', // LATIN SMALL LETTER E WITH CIRCUMFLEX
		"\xC3\xAB" => 'e', // LATIN SMALL LETTER E WITH DIAERESIS
		"\xC3\xAC" => 'i', // LATIN SMALL LETTER I WITH GRAVE
		"\xC3\xAD" => 'i', // LATIN SMALL LETTER I WITH ACUTE
		"\xC3\xAE" => 'i', // LATIN SMALL LETTER I WITH CIRCUMFLEX
		"\xC3\xAF" => 'i', // LATIN SMALL LETTER I WITH DIAERESIS
		"\xC3\xB1" => 'n', // LATIN SMALL LETTER N WITH TILDE
		"\xC3\xB2" => 'o', // LATIN SMALL LETTER O WITH GRAVE
		"\xC3\xB3" => 'o', // LATIN SMALL LETTER O WITH ACUTE
		"\xC3\xB4" => 'o', // LATIN SMALL LETTER O WITH CIRCUMFLEX
		"\xC3\xB5" => 'o', // LATIN SMALL LETTER O WITH TILDE
		"\xC3\xB6" => 'o', // LATIN SMALL LETTER O WITH DIAERESIS
		"\xC3\xB8" => 'o', // LATIN SMALL LETTER O WITH STROKE
		"\xC3\xB9" => 'u', // LATIN SMALL LETTER U WITH GRAVE
		"\xC3\xBA" => 'u', // LATIN SMALL LETTER U WITH ACUTE
		"\xC3\xBB" => 'u', // LATIN SMALL LETTER U WITH CIRCUMFLEX
		"\xC3\xBC" => 'u', // LATIN SMALL LETTER U WITH DIAERESIS
		"\xC3\xBD" => 'y', // LATIN SMALL LETTER Y WITH ACUTE
		"\xC3\xBF" => 'y', // LATIN SMALL LETTER Y WITH DIAERESIS
		"\xC4\x80" => 'A', // LATIN CAPITAL LETTER A WITH MACRON
		"\xC4\x81" => 'a', // LATIN SMALL LETTER A WITH MACRON
		"\xC4\x82" => 'A', // LATIN CAPITAL LETTER A WITH BREVE
		"\xC4\x83" => 'a', // LATIN SMALL LETTER A WITH BREVE
		"\xC4\x84" => 'A', // LATIN CAPITAL LETTER A WITH OGONEK
		"\xC4\x85" => 'a', // LATIN SMALL LETTER A WITH OGONEK
		"\xC4\x86" => 'C', // LATIN CAPITAL LETTER C WITH ACUTE
		"\xC4\x87" => 'c', // LATIN SMALL LETTER C WITH ACUTE
		"\xC4\x88" => 'C', // LATIN CAPITAL LETTER C WITH CIRCUMFLEX
		"\xC4\x89" => 'c', // LATIN SMALL LETTER C WITH CIRCUMFLEX
		"\xC4\x8A" => 'C', // LATIN CAPITAL LETTER C WITH DOT ABOVE
		"\xC4\x8B" => 'c', // LATIN SMALL LETTER C WITH DOT ABOVE
		"\xC4\x8C" => 'C', // LATIN CAPITAL LETTER C WITH CARON
		"\xC4\x8D" => 'c', // LATIN SMALL LETTER C WITH CARON
		"\xC4\x8E" => 'D', // LATIN CAPITAL LETTER D WITH CARON
		"\xC4\x8F" => 'd', // LATIN SMALL LETTER D WITH CARON
		"\xC4\x90" => 'D', // LATIN CAPITAL LETTER D WITH STROKE
		"\xC4\x91" => 'd', // LATIN SMALL LETTER D WITH STROKE
		"\xC4\x92" => 'E', // LATIN CAPITAL LETTER E WITH MACRON
		"\xC4\x93" => 'e', // LATIN SMALL LETTER E WITH MACRON
		"\xC4\x94" => 'E', // LATIN CAPITAL LETTER E WITH BREVE
		"\xC4\x95" => 'e', // LATIN SMALL LETTER E WITH BREVE
		"\xC4\x96" => 'E', // LATIN CAPITAL LETTER E WITH DOT ABOVE
		"\xC4\x97" => 'e', // LATIN SMALL LETTER E WITH DOT ABOVE
		"\xC4\x98" => 'E', // LATIN CAPITAL LETTER E WITH OGONEK
		"\xC4\x99" => 'e', // LATIN SMALL LETTER E WITH OGONEK
		"\xC4\x9A" => 'E', // LATIN CAPITAL LETTER E WITH CARON
		"\xC4\x9B" => 'e', // LATIN SMALL LETTER E WITH CARON
		"\xC4\x9C" => 'G', // LATIN CAPITAL LETTER G WITH CIRCUMFLEX
		"\xC4\x9D" => 'g', // LATIN SMALL LETTER G WITH CIRCUMFLEX
		"\xC4\x9E" => 'G', // LATIN CAPITAL LETTER G WITH BREVE
		"\xC4\x9F" => 'g', // LATIN SMALL LETTER G WITH BREVE
		"\xC4\xA0" => 'G', // LATIN CAPITAL LETTER G WITH DOT ABOVE
		"\xC4\xA1" => 'g', // LATIN SMALL LETTER G WITH DOT ABOVE
		"\xC4\xA2" => 'G', // LATIN CAPITAL LETTER G WITH CEDILLA
		"\xC4\xA3" => 'g', // LATIN SMALL LETTER G WITH CEDILLA
		"\xC4\xA4" => 'H', // LATIN CAPITAL LETTER H WITH CIRCUMFLEX
		"\xC4\xA5" => 'h', // LATIN SMALL LETTER H WITH CIRCUMFLEX
		"\xC4\xA6" => 'H', // LATIN CAPITAL LETTER H WITH STROKE
		"\xC4\xA7" => 'h', // LATIN SMALL LETTER H WITH STROKE
		"\xC4\xA8" => 'I', // LATIN CAPITAL LETTER I WITH TILDE
		"\xC4\xA9" => 'i', // LATIN SMALL LETTER I WITH TILDE
		"\xC4\xAA" => 'I', // LATIN CAPITAL LETTER I WITH MACRON
		"\xC4\xAB" => 'i', // LATIN SMALL LETTER I WITH MACRON
		"\xC4\xAC" => 'I', // LATIN CAPITAL LETTER I WITH BREVE
		"\xC4\xAD" => 'i', // LATIN SMALL LETTER I WITH BREVE
		"\xC4\xAE" => 'I', // LATIN CAPITAL LETTER I WITH OGONEK
		"\xC4\xAF" => 'i', // LATIN SMALL LETTER I WITH OGONEK
		"\xC4\xB0" => 'I', // LATIN CAPITAL LETTER I WITH DOT ABOVE
		"\xC4\xB1" => 'i', // LATIN SMALL LETTER DOTLESS I
		"\xC4\xB2" => 'IJ', // LATIN CAPITAL LIGATURE IJ
		"\xC4\xB3" => 'ij', // LATIN SMALL LIGATURE IJ
		"\xC4\xB4" => 'j', // LATIN CAPITAL LETTER J WITH CIRCUMFLEX
		"\xC4\xB5" => 'j', // LATIN SMALL LETTER J WITH CIRCUMFLEX
		"\xC4\xB6" => 'K', // LATIN CAPITAL LETTER K WITH CEDILLA
		"\xC4\xB7" => 'k', // LATIN SMALL LETTER K WITH CEDILLA
		"\xC4\xB9" => 'L', // LATIN CAPITAL LETTER L WITH ACUTE
		"\xC4\xBA" => 'l', // LATIN SMALL LETTER L WITH ACUTE
		"\xC4\xBB" => 'L', // LATIN CAPITAL LETTER L WITH CEDILLA
		"\xC4\xBC" => 'l', // LATIN SMALL LETTER L WITH CEDILLA
		"\xC4\xBD" => 'L', // LATIN CAPITAL LETTER L WITH CARON
		"\xC4\xBE" => 'l', // LATIN SMALL LETTER L WITH CARON
		"\xC4\xBF" => 'L', // LATIN CAPITAL LETTER L WITH MIDDLE DOT
		"\xC5\x80" => 'l', // LATIN SMALL LETTER L WITH MIDDLE DOT
		"\xC5\x81" => 'L', // LATIN CAPITAL LETTER L WITH STROKE
		"\xC5\x82" => 'l', // LATIN SMALL LETTER L WITH STROKE
		"\xC5\x83" => 'N', // LATIN CAPITAL LETTER N WITH ACUTE
		"\xC5\x84" => 'n', // LATIN SMALL LETTER N WITH ACUTE
		"\xC5\x85" => 'N', // LATIN CAPITAL LETTER N WITH CEDILLA
		"\xC5\x86" => 'n', // LATIN SMALL LETTER N WITH CEDILLA
		"\xC5\x87" => 'N', // LATIN CAPITAL LETTER N WITH CARON
		"\xC5\x88" => 'n', // LATIN SMALL LETTER N WITH CARON
		"\xC5\x8C" => 'O', // LATIN CAPITAL LETTER O WITH MACRON
		"\xC5\x8D" => 'o', // LATIN SMALL LETTER O WITH MACRON
		"\xC5\x8E" => 'O', // LATIN CAPITAL LETTER O WITH BREVE
		"\xC5\x8F" => 'o', // LATIN SMALL LETTER O WITH BREVE
		"\xC5\x90" => 'O', // LATIN CAPITAL LETTER O WITH DOUBLE ACUTE
		"\xC5\x91" => 'o', // LATIN SMALL LETTER O WITH DOUBLE ACUTE
		"\xC5\x92" => 'OE', // LATIN CAPITAL LIGATURE OE
		"\xC5\x93" => 'oe', // LATIN SMALL LIGATURE OE
		"\xC5\x94" => 'R', // LATIN CAPITAL LETTER R WITH ACUTE
		"\xC5\x95" => 'r', // LATIN SMALL LETTER R WITH ACUTE
		"\xC5\x96" => 'R', // LATIN CAPITAL LETTER R WITH CEDILLA
		"\xC5\x97" => 'r', // LATIN SMALL LETTER R WITH CEDILLA
		"\xC5\x98" => 'R', // LATIN CAPITAL LETTER R WITH CARON
		"\xC5\x99" => 'r', // LATIN SMALL LETTER R WITH CARON
		"\xC5\x9A" => 'S', // LATIN CAPITAL LETTER S WITH ACUTE
		"\xC5\x9B" => 's', // LATIN SMALL LETTER S WITH ACUTE
		"\xC5\x9C" => 'S', // LATIN CAPITAL LETTER S WITH CIRCUMFLEX
		"\xC5\x9D" => 's', // LATIN SMALL LETTER S WITH CIRCUMFLEX
		"\xC5\x9E" => 'S', // LATIN CAPITAL LETTER S WITH CEDILLA
		"\xC5\x9F" => 's', // LATIN SMALL LETTER S WITH CEDILLA
		"\xC5\xA0" => 'S', // LATIN CAPITAL LETTER S WITH CARON
		"\xC5\xA1" => 's', // LATIN SMALL LETTER S WITH CARON
		"\xC5\xA2" => 'T', // LATIN CAPITAL LETTER T WITH CEDILLA
		"\xC5\xA3" => 't', // LATIN SMALL LETTER T WITH CEDILLA
		"\xC5\xA4" => 'T', // LATIN CAPITAL LETTER T WITH CARON
		"\xC5\xA5" => 't', // LATIN SMALL LETTER T WITH CARON
		"\xC5\xA6" => 'T', // LATIN CAPITAL LETTER T WITH STROKE
		"\xC5\xA7" => 't', // LATIN SMALL LETTER T WITH STROKE
		"\xC5\xA8" => 'U', // LATIN CAPITAL LETTER U WITH TILDE
		"\xC5\xA9" => 'u', // LATIN SMALL LETTER U WITH TILDE
		"\xC5\xAA" => 'U', // LATIN CAPITAL LETTER U WITH MACRON
		"\xC5\xAB" => 'u', // LATIN SMALL LETTER U WITH MACRON
		"\xC5\xAC" => 'U', // LATIN CAPITAL LETTER U WITH BREVE
		"\xC5\xAD" => 'u', // LATIN SMALL LETTER U WITH BREVE
		"\xC5\xAE" => 'U', // LATIN CAPITAL LETTER U WITH RING ABOVE
		"\xC5\xAF" => 'u', // LATIN SMALL LETTER U WITH RING ABOVE
		"\xC5\xB0" => 'U', // LATIN CAPITAL LETTER U WITH DOUBLE ACUTE
		"\xC5\xB1" => 'u', // LATIN SMALL LETTER U WITH DOUBLE ACUTE
		"\xC5\xB2" => 'U', // LATIN CAPITAL LETTER U WITH OGONEK
		"\xC5\xB3" => 'u', // LATIN SMALL LETTER U WITH OGONEK
		"\xC5\xB4" => 'W', // LATIN CAPITAL LETTER W WITH CIRCUMFLEX
		"\xC5\xB5" => 'w', // LATIN SMALL LETTER W WITH CIRCUMFLEX
		"\xC5\xB6" => 'Y', // LATIN CAPITAL LETTER Y WITH CIRCUMFLEX
		"\xC5\xB7" => 'y', // LATIN SMALL LETTER Y WITH CIRCUMFLEX
		"\xC5\xB8" => 'Y', // LATIN CAPITAL LETTER Y WITH DIAERESIS
		"\xC5\xB9" => 'Z', // LATIN CAPITAL LETTER Z WITH ACUTE
		"\xC5\xBA" => 'z', // LATIN SMALL LETTER Z WITH ACUTE
		"\xC5\xBB" => 'Z', // LATIN CAPITAL LETTER Z WITH DOT ABOVE
		"\xC5\xBC" => 'z', // LATIN SMALL LETTER Z WITH DOT ABOVE
		"\xC5\xBD" => 'Z', // LATIN CAPITAL LETTER Z WITH CARON
		"\xC5\xBE" => 'z', // LATIN SMALL LETTER Z WITH CARON
		"\xC6\x80" => 'b', // LATIN SMALL LETTER B WITH STROKE
		"\xC6\x81" => 'B', // LATIN CAPITAL LETTER B WITH HOOK
		"\xC6\x82" => 'B', // LATIN CAPITAL LETTER B WITH TOPBAR
		"\xC6\x83" => 'b', // LATIN SMALL LETTER B WITH TOPBAR
		"\xC6\x87" => 'C', // LATIN CAPITAL LETTER C WITH HOOK
		"\xC6\x88" => 'c', // LATIN SMALL LETTER C WITH HOOK
		"\xC6\x89" => 'D', // LATIN CAPITAL LETTER AFRICAN D
		"\xC6\x8A" => 'D', // LATIN CAPITAL LETTER D WITH HOOK
		"\xC6\x8B" => 'D', // LATIN CAPITAL LETTER D WITH TOPBAR
		"\xC6\x8C" => 'd', // LATIN SMALL LETTER D WITH TOPBAR
		"\xC6\x91" => 'F', // LATIN CAPITAL LETTER F WITH HOOK
		"\xC6\x92" => 'f', // LATIN SMALL LETTER F WITH HOOK
		"\xC6\x93" => 'G', // LATIN CAPITAL LETTER G WITH HOOKU+0195
		"\xC6\x97" => 'I', // LATIN CAPITAL LETTER I WITH STROKE
		"\xC6\x98" => 'K', // LATIN CAPITAL LETTER K WITH HOOK
		"\xC6\x99" => 'k', // LATIN SMALL LETTER K WITH HOOK
		"\xC6\x9A" => 'l', // LATIN SMALL LETTER L WITH BAR
		"\xC6\x9D" => 'N', // LATIN CAPITAL LETTER N WITH LEFT HOOK
		"\xC6\x9E" => 'n', // LATIN SMALL LETTER N WITH LONG RIGHT LEG
		"\xC6\x9F" => 'O', // LATIN CAPITAL LETTER O WITH MIDDLE TILDE
		"\xC6\xA0" => 'O', // LATIN CAPITAL LETTER O WITH HORN
		"\xC6\xA1" => 'o', // LATIN SMALL LETTER O WITH HORN
		"\xC6\xA2" => 'OI', // LATIN CAPITAL LETTER OI
		"\xC6\xA3" => 'oi', // LATIN SMALL LETTER OI
		"\xC6\xA4" => 'P', // LATIN CAPITAL LETTER P WITH HOOK
		"\xC6\xA5" => 'p', // LATIN SMALL LETTER P WITH HOOK
		"\xC6\xAB" => 't', // LATIN SMALL LETTER T WITH PALATAL HOOK
		"\xC6\xAC" => 'T', // LATIN CAPITAL LETTER T WITH HOOK
		"\xC6\xAD" => 't', // LATIN SMALL LETTER T WITH HOOK
		"\xC6\xAE" => 'T', // LATIN CAPITAL LETTER T WITH RETROFLEX HOOK
		"\xC6\xAF" => 'U', // LATIN CAPITAL LETTER U WITH HORN
		"\xC6\xB0" => 'u', // LATIN SMALL LETTER U WITH HORN
		"\xC6\xB2" => 'V', // LATIN CAPITAL LETTER V WITH HOOK
		"\xC6\xB3" => 'Y', // LATIN CAPITAL LETTER Y WITH HOOK
		"\xC6\xB4" => 'y', // LATIN SMALL LETTER Y WITH HOOK
		"\xC6\xB5" => 'Z', // LATIN CAPITAL LETTER Z WITH STROKE
		"\xC6\xB6" => 'z', // LATIN SMALL LETTER Z WITH STROKE
		"\xC7\x8D" => 'A', // LATIN CAPITAL LETTER A WITH CARON
		"\xC7\x8E" => 'a', // LATIN SMALL LETTER A WITH CARON
		"\xC7\x8F" => 'I', // LATIN CAPITAL LETTER I WITH CARON
		"\xC7\x90" => 'i', // LATIN SMALL LETTER I WITH CARON
		"\xC7\x91" => 'O', // LATIN CAPITAL LETTER O WITH CARON
		"\xC7\x92" => 'o', // LATIN SMALL LETTER O WITH CARON
		"\xC7\x93" => 'U', // LATIN CAPITAL LETTER U WITH CARON
		"\xC7\x94" => 'u', // LATIN SMALL LETTER U WITH CARON
		"\xC7\x95" => 'U', // LATIN CAPITAL LETTER U WITH DIAERESIS AND MACRON
		"\xC7\x96" => 'u', // LATIN SMALL LETTER U WITH DIAERESIS AND MACRON
		"\xC7\x97" => 'U', // LATIN CAPITAL LETTER U WITH DIAERESIS AND ACUTE
		"\xC7\x98" => 'u', // LATIN SMALL LETTER U WITH DIAERESIS AND ACUTE
		"\xC7\x99" => 'U', // LATIN CAPITAL LETTER U WITH DIAERESIS AND CARON
		"\xC7\x9A" => 'u', // LATIN SMALL LETTER U WITH DIAERESIS AND CARON
		"\xC7\x9B" => 'U', // LATIN CAPITAL LETTER U WITH DIAERESIS AND GRAVE
		"\xC7\x9C" => 'u', // LATIN SMALL LETTER U WITH DIAERESIS AND GRAVE
		"\xC7\x9E" => 'A', // LATIN CAPITAL LETTER A WITH DIAERESIS AND MACRON
		"\xC7\x9F" => 'a', // LATIN SMALL LETTER A WITH DIAERESIS AND MACRON
		"\xC7\xA0" => 'A', // LATIN CAPITAL LETTER A WITH DOT ABOVE AND MACRON
		"\xC7\xA1" => 'a', // LATIN SMALL LETTER A WITH DOT ABOVE AND MACRON
		"\xC7\xA2" => 'AE', // LATIN CAPITAL LETTER AE WITH MACRON
		"\xC7\xA3" => 'ae', // LATIN SMALL LETTER AE WITH MACRON
		"\xC7\xA4" => 'G', // LATIN CAPITAL LETTER G WITH STROKE
		"\xC7\xA5" => 'g', // LATIN SMALL LETTER G WITH STROKE
		"\xC7\xA6" => 'G', // LATIN CAPITAL LETTER G WITH CARON
		"\xC7\xA7" => 'g', // LATIN SMALL LETTER G WITH CARON
		"\xC7\xA8" => 'K', // LATIN CAPITAL LETTER K WITH CARON
		"\xC7\xA9" => 'k', // LATIN SMALL LETTER K WITH CARON
		"\xC7\xAA" => 'O', // LATIN CAPITAL LETTER O WITH OGONEK
		"\xC7\xAB" => 'o', // LATIN SMALL LETTER O WITH OGONEK
		"\xC7\xAC" => 'O', // LATIN CAPITAL LETTER O WITH OGONEK AND MACRON
		"\xC7\xAD" => 'o', // LATIN SMALL LETTER O WITH OGONEK AND MACRON
		"\xC7\xB0" => 'j', // LATIN SMALL LETTER J WITH CARON
		"\xC7\xB4" => 'G', // LATIN CAPITAL LETTER G WITH ACUTE
		"\xC7\xB5" => 'g', // LATIN SMALL LETTER G WITH ACUTE
		"\xC7\xB8" => 'N', // LATIN CAPITAL LETTER N WITH GRAVE
		"\xC7\xB9" => 'n', // LATIN SMALL LETTER N WITH GRAVE
		"\xC7\xBA" => 'A', // LATIN CAPITAL LETTER A WITH RING ABOVE AND ACUTE
		"\xC7\xBB" => 'a', // LATIN SMALL LETTER A WITH RING ABOVE AND ACUTE
		"\xC7\xBC" => 'AE', // LATIN CAPITAL LETTER AE WITH ACUTE
		"\xC7\xBD" => 'ae', // LATIN SMALL LETTER AE WITH ACUTE
		"\xC7\xBE" => 'O', // LATIN CAPITAL LETTER O WITH STROKE AND ACUTE
		"\xC7\xBF" => 'o', // LATIN SMALL LETTER O WITH STROKE AND ACUTE
		"\xC8\x80" => 'A', // LATIN CAPITAL LETTER A WITH DOUBLE GRAVE
		"\xC8\x81" => 'a', // LATIN SMALL LETTER A WITH DOUBLE GRAVE
		"\xC8\x82" => 'A', // LATIN CAPITAL LETTER A WITH INVERTED BREVE
		"\xC8\x83" => 'a', // LATIN SMALL LETTER A WITH INVERTED BREVE
		"\xC8\x84" => 'E', // LATIN CAPITAL LETTER E WITH DOUBLE GRAVE
		"\xC8\x85" => 'e', // LATIN SMALL LETTER E WITH DOUBLE GRAVE
		"\xC8\x86" => 'E', // LATIN CAPITAL LETTER E WITH INVERTED BREVE
		"\xC8\x87" => 'e', // LATIN SMALL LETTER E WITH INVERTED BREVE
		"\xC8\x88" => 'I', // LATIN CAPITAL LETTER I WITH DOUBLE GRAVE
		"\xC8\x89" => 'i', // LATIN SMALL LETTER I WITH DOUBLE GRAVE
		"\xC8\x8A" => 'I', // LATIN CAPITAL LETTER I WITH INVERTED BREVE
		"\xC8\x8B" => 'i', // LATIN SMALL LETTER I WITH INVERTED BREVE
		"\xC8\x8C" => 'O', // LATIN CAPITAL LETTER O WITH DOUBLE GRAVE
		"\xC8\x8D" => 'o', // LATIN SMALL LETTER O WITH DOUBLE GRAVE
		"\xC8\x8E" => 'O', // LATIN CAPITAL LETTER O WITH INVERTED BREVE
		"\xC8\x8F" => 'o', // LATIN SMALL LETTER O WITH INVERTED BREVE
		"\xC8\x90" => 'R', // LATIN CAPITAL LETTER R WITH DOUBLE GRAVE
		"\xC8\x91" => 'r', // LATIN SMALL LETTER R WITH DOUBLE GRAVE
		"\xC8\x92" => 'R', // LATIN CAPITAL LETTER R WITH INVERTED BREVE
		"\xC8\x93" => 'r', // LATIN SMALL LETTER R WITH INVERTED BREVE
		"\xC8\x94" => 'U', // LATIN CAPITAL LETTER U WITH DOUBLE GRAVE
		"\xC8\x95" => 'u', // LATIN SMALL LETTER U WITH DOUBLE GRAVE
		"\xC8\x96" => 'U', // LATIN CAPITAL LETTER U WITH INVERTED BREVE
		"\xC8\x97" => 'u', // LATIN SMALL LETTER U WITH INVERTED BREVE
		"\xC8\x98" => 'S', // LATIN CAPITAL LETTER S WITH COMMA BELOW
		"\xC8\x99" => 's', // LATIN SMALL LETTER S WITH COMMA BELOW
		"\xC8\x9A" => 'T', // LATIN CAPITAL LETTER T WITH COMMA BELOW
		"\xC8\x9B" => 't', // LATIN SMALL LETTER T WITH COMMA BELOW
		"\xC8\x9E" => 'H', // LATIN CAPITAL LETTER H WITH CARON
		"\xC8\x9F" => 'h', // LATIN SMALL LETTER H WITH CARON
		"\xC8\xA0" => 'n', // LATIN CAPITAL LETTER N WITH LONG RIGHT LEG
		"\xC8\xA1" => 'd', // LATIN SMALL LETTER D WITH CURL
		"\xC8\xA4" => 'Z', // LATIN CAPITAL LETTER Z WITH HOOK
		"\xC8\xA5" => 'z', // LATIN SMALL LETTER Z WITH HOOK
		"\xC8\xA6" => 'A', // LATIN CAPITAL LETTER A WITH DOT ABOVE
		"\xC8\xA7" => 'a', // LATIN SMALL LETTER A WITH DOT ABOVE
		"\xC8\xA8" => 'E', // LATIN CAPITAL LETTER E WITH CEDILLA
		"\xC8\xA9" => 'e', // LATIN SMALL LETTER E WITH CEDILLA
		"\xC8\xAA" => 'O', // LATIN CAPITAL LETTER O WITH DIAERESIS AND MACRON
		"\xC8\xAB" => 'o', // LATIN SMALL LETTER O WITH DIAERESIS AND MACRON
		"\xC8\xAC" => 'O', // LATIN CAPITAL LETTER O WITH TILDE AND MACRON
		"\xC8\xAD" => 'o', // LATIN SMALL LETTER O WITH TILDE AND MACRON
		"\xC8\xAE" => 'O', // LATIN CAPITAL LETTER O WITH DOT ABOVE
		"\xC8\xAF" => 'o', // LATIN SMALL LETTER O WITH DOT ABOVE
		"\xC8\xB0" => 'O', // LATIN CAPITAL LETTER O WITH DOT ABOVE AND MACRON
		"\xC8\xB1" => 'o', // LATIN SMALL LETTER O WITH DOT ABOVE AND MACRON
		"\xC8\xB2" => 'Y', // LATIN CAPITAL LETTER Y WITH MACRON
		"\xC8\xB3" => 'y', // LATIN SMALL LETTER Y WITH MACRON
		"\xC8\xB4" => 'l', // LATIN SMALL LETTER L WITH CURL
		"\xC8\xB5" => 'n', // LATIN SMALL LETTER N WITH CURL
		"\xC8\xB6" => 't', // LATIN SMALL LETTER T WITH CURL
		"\xC8\xB7" => 'j', // LATIN SMALL LETTER DOTLESS J
	);


	/**
	 * Return the UTF-8 input string converted into an array of words, changed $tolowercase (or not).
	 *
	 * Set $delimiters to true to keep the delimiters after each word and tweak what we used for word
	 * splitting with $splitideographs and $splithyphens.
	 */
	public static function stringToWords($string, $tolowercase=true, $delimiters=false, $splitideographs=true, $splithyphens=true)
	{
		if ($tolowercase)
			$string = self::strtolower($string);

		$string = strtr($string, self::$utf8Punctuation);

		$separator = self::$pregIndexWordSeparator;
		if ($splithyphens)
			$separator .= '|\-';

		if ($delimiters) {
			if ($splitideographs)
				$separator .= '|' . self::$pregCjkIdeographsUtf8;
		}
		else {
			// remove apostrophes in words
			$string = preg_replace("/(\S)'(\S)/", '\1\2', $string);
			// put spaces around CJK ideographs so they're treated as separate words
			if ($splitideographs)
				$string = preg_replace('/'.self::$pregCjkIdeographsUtf8.'/', ' \0 ', $string);
		}

		return preg_split('/('.$separator.'+)/', $string, -1, PREG_SPLIT_NO_EMPTY | ($delimiters ? PREG_SPLIT_DELIM_CAPTURE : 0));
	}


	/**
	 * Return UTF-8 input $string with all accents (on Roman characters) removed
	 */
	public static function removeAccents($string)
	{
		return strtr($string, self::$utf8RemoveAccents);
	}


	/**
	 * Convert an array of tags into a string for storage in the database
	 */
	public static function tagsToTagstring($tags)
	{
		return implode(',', $tags);
	}


	/**
	 * Convert a tag string as stored in the database into an array of tags
	 */
	public static function tagstringToTags($tagstring)
	{
		return empty($tagstring) ? array() : explode(',', $tagstring);
	}


	/**
	 * Return no more than $length characters from $string after converting it to a single line, by
	 * removing words from the middle (and especially towards the end)
	 */
	public static function shortenStringLine($string, $length)
	{
		$string = strtr($string, "\r\n\t", '   ');

		if (self::strlen($string) > $length) {
			$remaining = $length - 5;

			$words = self::stringToWords($string, false, true);
			$countwords = count($words);

			$prefix = '';
			$suffix = '';

			for ($addword = 0; $addword < $countwords; $addword++) {
				$tosuffix = ($addword%3) == 1; // order: prefix, suffix, prefix, prefix, suffix, prefix, ...

				if ($tosuffix)
					$word = array_pop($words);
				else
					$word = array_shift($words);

				if (self::strlen($word) > $remaining)
					break;

				if ($tosuffix)
					$suffix = $word.$suffix;
				else
					$prefix .= $word;

				$remaining -= self::strlen($word);
			}

			$string = $prefix.' ... '.$suffix;
		}

		return $string;
	}


	/**
	 * Return an array of the words within $wordstring, each of which can contain asterisks
	 */
	public static function blockWordsExplode($wordstring)
	{
		return preg_split('/'.self::$pregBlockWordSeparator.'+/', $wordstring, -1, PREG_SPLIT_NO_EMPTY);
	}


	/**
	 * Return a regular expression fragment corresponding to the block words $wordstring
	 */
	public static function blockWordsToPreg($wordsstring)
	{
		$blockwords = self::blockWordsExplode($wordsstring);
		$patterns = array();

		foreach ($blockwords as $blockword) {
			// * in rule maps to [^ ]* in regular expression
			$pattern = str_replace('\\*', '[^ ]*', preg_quote(self::strtolower($blockword), '/'));

			// assert leading word delimiter if pattern does not start with CJK
			if (!preg_match('/^('.self::$pregCjkIdeographsUtf8.')/', $blockword))
				$pattern = '(?<= )' . $pattern;

			// assert trailing word delimiter if pattern does not end with CJK
			if (!preg_match('/('.self::$pregCjkIdeographsUtf8.')$/', $blockword))
				$pattern = $pattern . '(?= )';

			$patterns[] = $pattern;
		}

		return implode('|', $patterns);
	}


	/**
	 *Return an array of matches of the regular expression fragment $wordspreg in $string, [offset] => [length]
	 */
	public static function blockWordsMatchAll($string, $wordspreg)
	{
		if (strlen($wordspreg)) {
			// replace all word separators with spaces of same length

			if (empty(self::$utf8PunctuationKeepLength)) {
				foreach (self::$utf8Punctuation as $key=>$value)
					self::$utf8PunctuationKeepLength[$key] = str_repeat(' ', strlen($key));
			}

			// assumes UTF-8 case conversion in self::strtolower does not change byte length
			$string = strtr(self::strtolower($string), self::$utf8PunctuationKeepLength);
			$string = preg_replace('/'.self::$pregBlockWordSeparator.'/', ' ', $string);

			preg_match_all('/'.$wordspreg.'/', ' '.$string.' ', $pregmatches, PREG_OFFSET_CAPTURE);

			$outmatches = array();
			foreach ($pregmatches[0] as $pregmatch)
				$outmatches[$pregmatch[1]-1] = strlen($pregmatch[0]);

			return $outmatches;
		}

		return array();
	}


	/**
	 * Return $string with any words matching the regular expression fragment $wordspreg replaced with repeated $character
	 */
	public static function blockWordsReplace($string, $wordspreg, $character='*')
	{
		if (strlen($wordspreg)) {
			$matches = self::blockWordsMatchAll($string, $wordspreg);
			krsort($matches, SORT_NUMERIC);

			// get length again below to deal with multi-byte characters
			foreach ($matches as $start => $length)
				$string = substr_replace($string, str_repeat($character, self::strlen(substr($string, $start, $length))), $start, $length);
		}

		return $string;
	}


	/**
	 * Return a random alphanumeric string (base 36) of $length
	 */
	public static function randomAlphanum($length)
	{
		$string = '';

		while (strlen($string) < $length)
			$string .= str_pad(base_convert(mt_rand(0, 46655), 10, 36), 3, '0', STR_PAD_LEFT);

		return substr($string, 0, $length);
	}


	/**
	 * Return true or false to indicate whether $email is a valid email (this is pretty flexible compared to most real emails out there)
	 */
	public static function emailValidate($email)
	{
		return preg_match("/^[\-\!\#\$\%\&\'\*\+\/\=\?\_\`\{\|\}\~a-zA-Z0-9\.\^]+\@[a-zA-Z0-9\-]+\.[a-zA-Z0-9\.\-]+$/", $email) === 1;
	}


	/**
	 * Return the number of characters in $string, preferably using PHP's multibyte string functions
	 */
	public static function strlen($string)
	{
		return function_exists('mb_strlen') ? mb_strlen($string, 'UTF-8') : strlen($string);
	}


	/**
	 * Return a lower case version of $string, preferably using PHP's multibyte string functions
	 */
	public static function strtolower($string)
	{
		return function_exists('mb_strtolower') ? mb_strtolower($string, 'UTF-8') : strtolower($string);
	}


	/**
	 * Return $length characters from $string, starting from $start, preferably using PHP's multibyte string functions
	 */
	public static function substr($string, $start, $length=2147483647)
	{
		return function_exists('mb_substr') ? mb_substr($string, $start, $length, 'UTF-8') : substr($string, $start, $length);
	}


	/**
	 * Return whether this version of PHP has been compiled with multibyte string support
	 */
	public static function hasMultibyte()
	{
		return function_exists('mb_strlen') && function_exists('mb_strtolower');
	}


	/**
	 * Return true if one of the elements in $matches is contained within $string
	 */
	public static function stringMatchesOne($string, $matches)
	{
		if (strlen($string)) {
			foreach ($matches as $match) {
				if (strpos($string, $match) !== false)
					return true;
			}
		}

		return false;
	}

}
