utf8.php
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Created: Sat, May 18, 05:15

utf8.php
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	<?php

	/**
	* Convert a string into valid UTF-8. This function is quite slow.
	*
	* When invalid byte subsequences are encountered, they will be replaced with
	* U+FFFD, the Unicode replacement character.
	*
	* @param string String to convert to valid UTF-8.
	* @return string String with invalid UTF-8 byte subsequences replaced with
	* U+FFFD.
	* @group utf8
	*/
	function phutil_utf8ize($string) {
	if (phutil_is_utf8($string)) {
	return $string;
	}

	// There is no function to do this in iconv, mbstring or ICU to do this, so
	// do it (very very slowly) in pure PHP.

	// TODO: Provide an optional fast C implementation ala fb_utf8ize() if this
	// ever shows up in profiles?

	$result = array();

	$regex =
	"/([\x01-\x7F]".
	"\|[\xC2-\xDF][\x80-\xBF]".
	"\|[\xE0-\xEF][\x80-\xBF][\x80-\xBF]".
	"\|[\xF0-\xF4][\x80-\xBF][\x80-\xBF][\x80-\xBF])".
	"\|(.)/";

	$offset = 0;
	$matches = null;
	while (preg_match($regex, $string, $matches, 0, $offset)) {
	if (!isset($matches[2])) {
	$result[] = $matches[1];
	} else {
	// Unicode replacement character, U+FFFD.
	$result[] = "\xEF\xBF\xBD";
	}
	$offset += strlen($matches[0]);
	}

	return implode('', $result);
	}


	/**
	* Determine if a string is valid UTF-8.
	*
	* @param string Some string which may or may not be valid UTF-8.
	* @return bool True if the string is valid UTF-8.
	* @group utf8
	*/
	function phutil_is_utf8($string) {
	if (function_exists('mb_check_encoding')) {
	// If mbstring is available, this is significantly faster than using PHP
	// regexps.
	return mb_check_encoding($string, 'UTF-8');
	}

	$regex =
	"/^(".
	"[\x01-\x7F]+".
	"\|([\xC2-\xDF][\x80-\xBF])".
	"\|([\xE0-\xEF][\x80-\xBF][\x80-\xBF])".
	"\|([\xF0-\xF4][\x80-\xBF][\x80-\xBF][\x80-\xBF]))*\$/";

	return preg_match($regex, $string);
	}


	/**
	* Find the character length of a UTF-8 string.
	*
	* @param string A valid utf-8 string.
	* @return int The character length of the string.
	* @group utf8
	*/
	function phutil_utf8_strlen($string) {
	return strlen(utf8_decode($string));
	}


	/**
	* Find the console display length of a UTF-8 string. This may differ from the
	* character length of the string if it contains double-width characters, like
	* many Chinese characters.
	*
	* This method is based on a C implementation here, which is based on the IEEE
	* standards. The source has more discussion and addresses more considerations
	* than this implementation does.
	*
	* http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c
	*
	* NOTE: We currently do not handle combining characters correctly.
	*
	* NOTE: We currently assume width 1 for East-Asian ambiguous characters.
	*
	* NOTE: This function is VERY slow.
	*
	* @param string A valid UTF-8 string.
	* @return int The console display length of the string.
	* @group utf8
	*/
	function phutil_utf8_console_strlen($string) {
	$string_v = phutil_utf8v_codepoints($string);

	$len = 0;
	foreach ($string_v as $c) {
	if ($c == 0) {
	continue;
	}

	$len += 1 +
	($c >= 0x1100 &&
	($c <= 0x115f \|\| /* Hangul Jamo init. consonants */
	$c == 0x2329 \|\| $c == 0x232a \|\|
	($c >= 0x2e80 && $c <= 0xa4cf &&
	$c != 0x303f) \|\| /* CJK ... Yi */
	($c >= 0xac00 && $c <= 0xd7a3) \|\| /* Hangul Syllables */
	($c >= 0xf900 && $c <= 0xfaff) \|\| /* CJK Compatibility Ideographs */
	($c >= 0xfe10 && $c <= 0xfe19) \|\| /* Vertical forms */
	($c >= 0xfe30 && $c <= 0xfe6f) \|\| /* CJK Compatibility Forms */
	($c >= 0xff00 && $c <= 0xff60) \|\| /* Fullwidth Forms */
	($c >= 0xffe0 && $c <= 0xffe6) \|\|
	($c >= 0x20000 && $c <= 0x2fffd) \|\|
	($c >= 0x30000 && $c <= 0x3fffd)));
	}

	return $len;
	}


	/**
	* Split a UTF-8 string into an array of characters. Combining characters are
	* also split.
	*
	* @param string A valid utf-8 string.
	* @return list A list of characters in the string.
	* @group utf8
	*/
	function phutil_utf8v($string) {
	$res = array();
	$len = strlen($string);
	$ii = 0;
	while ($ii < $len) {
	$byte = $string[$ii];
	if ($byte <= "\x7F") {
	$res[] = $byte;
	$ii += 1;
	continue;
	} else if ($byte < "\xC0") {
	throw new Exception("Invalid UTF-8 string passed to phutil_utf8v().");
	} else if ($byte <= "\xDF") {
	$seq_len = 2;
	} else if ($byte <= "\xEF") {
	$seq_len = 3;
	} else if ($byte <= "\xF7") {
	$seq_len = 4;
	} else if ($byte <= "\xFB") {
	$seq_len = 5;
	} else if ($byte <= "\xFD") {
	$seq_len = 6;
	} else {
	throw new Exception("Invalid UTF-8 string passed to phutil_utf8v().");
	}

	if ($ii + $seq_len > $len) {
	throw new Exception("Invalid UTF-8 string passed to phutil_utf8v().");
	}
	for ($jj = 1; $jj < $seq_len; ++$jj) {
	if ($string[$ii + $jj] >= "\xC0") {
	throw new Exception("Invalid UTF-8 string passed to phutil_utf8v().");
	}
	}
	$res[] = substr($string, $ii, $seq_len);
	$ii += $seq_len;
	}
	return $res;
	}


	/**
	* Split a UTF-8 string into an array of codepoints (as integers).
	*
	* @param string A valid UTF-8 string.
	* @return list A list of codepoints, as integers.
	* @group utf8
	*/
	function phutil_utf8v_codepoints($string) {
	$str_v = phutil_utf8v($string);

	foreach ($str_v as $key => $char) {
	$c = ord($char[0]);
	$v = 0;

	if (($c & 0x80) == 0) {
	$v = $c;
	} else if (($c & 0xE0) == 0xC0) {
	$v = (($c & 0x1F) << 6)
	+ ((ord($char[1]) & 0x3F));
	} else if (($c & 0xF0) == 0xE0) {
	$v = (($c & 0x0F) << 12)
	+ ((ord($char[1]) & 0x3f) << 6)
	+ ((ord($char[2]) & 0x3f));
	} else if (($c & 0xF8) == 0xF0) {
	$v = (($c & 0x07) << 18)
	+ ((ord($char[1]) & 0x3F) << 12)
	+ ((ord($char[2]) & 0x3F) << 6)
	+ ((ord($char[3]) & 0x3f));
	} else if (($c & 0xFC) == 0xF8) {
	$v = (($c & 0x03) << 24)
	+ ((ord($char[1]) & 0x3F) << 18)
	+ ((ord($char[2]) & 0x3F) << 12)
	+ ((ord($char[3]) & 0x3f) << 6)
	+ ((ord($char[4]) & 0x3f));
	} else if (($c & 0xFE) == 0xFC) {
	$v = (($c & 0x01) << 30)
	+ ((ord($char[1]) & 0x3F) << 24)
	+ ((ord($char[2]) & 0x3F) << 18)
	+ ((ord($char[3]) & 0x3f) << 12)
	+ ((ord($char[4]) & 0x3f) << 6)
	+ ((ord($char[5]) & 0x3f));
	}

	$str_v[$key] = $v;
	}

	return $str_v;
	}


	/**
	* Shorten a string to provide a summary, respecting UTF-8 characters. This
	* function attempts to truncate strings at word boundaries.
	*
	* NOTE: This function makes a best effort to apply some reasonable rules but
	* will not work well for the full range of unicode languages.
	*
	* @param string UTF-8 string to shorten.
	* @param int Maximum length of the result.
	* @param string If the string is shortened, add this at the end. Defaults to
	* horizontal ellipsis.
	* @return string A string with no more than the specified character length.
	*
	* @group utf8
	*/
	function phutil_utf8_shorten($string, $length, $terminal = "\xE2\x80\xA6") {
	// If the string has fewer bytes than the minimum length, we can return
	// it unmodified without doing any heavy lifting.
	if (strlen($string) <= $length) {
	return $string;
	}

	$string_v = phutil_utf8v_combined($string);
	$string_len = count($string_v);

	if ($string_len <= $length) {
	// If the string is already shorter than the requested length, simply return
	// it unmodified.
	return $string;
	}

	// NOTE: This is not complete, and there are many other word boundary
	// characters and reasonable places to break words in the UTF-8 character
	// space. For now, this gives us reasonable behavior for latin langauges. We
	// don't necessarily have access to PCRE+Unicode so there isn't a great way
	// for us to look up character attributes.

	// If we encounter these, prefer to break on them instead of cutting the
	// string off in the middle of a word.
	static $break_characters = array(
	' ' => true,
	"\n" => true,
	';' => true,
	':' => true,
	'[' => true,
	'(' => true,
	',' => true,
	'-' => true,
	);

	// If we encounter these, shorten to this character exactly without appending
	// the terminal.
	static $stop_characters = array(
	'.' => true,
	'!' => true,
	'?' => true,
	);

	// Search backward in the string, looking for reasonable places to break it.
	$word_boundary = null;
	$stop_boundary = null;

	$terminal_len = phutil_utf8_strlen($terminal);

	// If we do a word break with a terminal, we have to look beyond at least the
	// number of characters in the terminal. If the terminal is longer than the
	// required length, we'll skip this whole block and return it on its own
	$terminal_area = $length - min($length, $terminal_len);
	for ($ii = $length; $ii >= 0; $ii--) {
	$c = $string_v[$ii];

	if (isset($break_characters[$c]) && ($ii <= $terminal_area)) {
	$word_boundary = $ii;
	} else if (isset($stop_characters[$c]) && ($ii < $length)) {
	$stop_boundary = $ii + 1;
	break;
	} else {
	if ($word_boundary !== null) {
	break;
	}
	}
	}

	if ($stop_boundary !== null) {
	// We found a character like ".". Cut the string there, without appending
	// the terminal.
	$string_part = array_slice($string_v, 0, $stop_boundary);
	return implode('', $string_part);
	}

	// If we didn't find any boundary characters or we found ONLY boundary
	// characters, just break at the maximum character length.
	if ($word_boundary === null \|\| $word_boundary === 0) {
	$word_boundary = $terminal_area;
	}

	$string_part = array_slice($string_v, 0, $word_boundary);
	$string_part = implode('', $string_part);
	return $string_part.$terminal;
	}


	/**
	* Hard-wrap a block of UTF-8 text with embedded HTML tags and entities.
	*
	* @param string An HTML string with tags and entities.
	* @return list List of hard-wrapped lines.
	* @group utf8
	*/
	function phutil_utf8_hard_wrap_html($string, $width) {
	$break_here = array();

	// Convert the UTF-8 string into a list of UTF-8 characters.
	$vector = phutil_utf8v($string);
	$len = count($vector);
	$char_pos = 0;
	for ($ii = 0; $ii < $len; ++$ii) {
	// An ampersand indicates an HTML entity; consume the whole thing (until
	// ";") but treat it all as one character.
	if ($vector[$ii] == '&') {
	do {
	++$ii;
	} while ($vector[$ii] != ';');
	++$char_pos;
	// An "<" indicates an HTML tag, consume the whole thing but don't treat
	// it as a character.
	} else if ($vector[$ii] == '<') {
	do {
	++$ii;
	} while ($vector[$ii] != '>');
	} else {
	++$char_pos;
	}

	// Keep track of where we need to break the string later.
	if ($char_pos == $width) {
	$break_here[$ii] = true;
	$char_pos = 0;
	}
	}

	$result = array();
	$string = '';
	foreach ($vector as $ii => $char) {
	$string .= $char;
	if (isset($break_here[$ii])) {
	$result[] = $string;
	$string = '';
	}
	}

	if (strlen($string)) {
	$result[] = $string;
	}

	return $result;
	}

	/**
	* Hard-wrap a block of UTF-8 text with no embedded HTML tags and entitites
	*
	* @param string A non HTML string
	* @param int Width of the hard-wrapped lines
	* @return list List of hard-wrapped lines.
	* @group utf8
	*/
	function phutil_utf8_hard_wrap($string, $width) {
	$result = array();

	$lines = phutil_split_lines($string, $retain_endings = false);
	foreach ($lines as $line) {

	// Convert the UTF-8 string into a list of UTF-8 characters.
	$vector = phutil_utf8v($line);

	$len = count($vector);
	$buffer = '';

	for ($ii = 1; $ii <= $len; ++$ii) {
	$buffer .= $vector[$ii - 1];
	if (($ii % $width) === 0) {
	$result[] = $buffer;
	$buffer = '';
	}
	}

	if (strlen($buffer)) {
	$result[] = $buffer;
	}
	}

	return $result;
	}

	/**
	* Convert a string from one encoding (like ISO-8859-1) to another encoding
	* (like UTF-8).
	*
	* This is primarily a thin wrapper around `mb_convert_encoding()` which checks
	* you have the extension installed, since we try to require the extension
	* only if you actually need it (i.e., you want to work with encodings other
	* than UTF-8).
	*
	* NOTE: This function assumes that the input is in the given source encoding.
	* If it is not, it may not output in the specified target encoding. If you
	* need to perform a hard conversion to UTF-8, use this function in conjunction
	* with @{function:phutil_utf8ize}. We can detect failures caused by invalid
	* encoding names, but `mb_convert_encoding()` fails silently if the
	* encoding name identifies a real encoding but the string is not actually
	* encoded with that encoding.
	*
	* @param string String to re-encode.
	* @param string Target encoding name, like "UTF-8".
	* @param string Source endocing name, like "ISO-8859-1".
	* @return string Input string, with converted character encoding.
	*
	* @group utf8
	*
	* @phutil-external-symbol function mb_convert_encoding
	*/
	function phutil_utf8_convert($string, $to_encoding, $from_encoding) {
	if (!$from_encoding) {
	throw new InvalidArgumentException(
	"Attempting to convert a string encoding, but no source encoding ".
	"was provided. Explicitly provide the source encoding.");
	}
	if (!$to_encoding) {
	throw new InvalidArgumentException(
	"Attempting to convert a string encoding, but no target encoding ".
	"was provided. Explicitly provide the target encoding.");
	}

	// Normalize encoding names so we can no-op the very common case of UTF8
	// to UTF8 (or any other conversion where both encodings are identical).
	$to_upper = strtoupper(str_replace('-', '', $to_encoding));
	$from_upper = strtoupper(str_replace('-', '', $from_encoding));
	if ($from_upper == $to_upper) {
	return $string;
	}

	if (!function_exists('mb_convert_encoding')) {
	throw new Exception(
	"Attempting to convert a string encoding from '{$from_encoding}' ".
	"to '{$to_encoding}', but the 'mbstring' PHP extension is not ".
	"available. Install mbstring to work with encodings other than ".
	"UTF-8.");
	}

	$result = @mb_convert_encoding($string, $to_encoding, $from_encoding);

	if ($result === false) {
	$message = error_get_last();
	if ($message) {
	$message = idx($message, 'message', 'Unknown error.');
	}
	throw new Exception(
	"String conversion from encoding '{$from_encoding}' to encoding ".
	"'{$to_encoding}' failed: {$message}");
	}

	return $result;
	}


	/**
	* Convert a string to title case in a UTF8-aware way. This function doesn't
	* necessarily do a great job, but the builtin implementation of ucwords() can
	* completely destroy inputs, so it just has to be better than that. Similar to
	* @{function:ucwords}.
	*
	* @param string UTF-8 input string.
	* @return string Input, in some semblance of title case.
	*
	* @group utf8
	*/
	function phutil_utf8_ucwords($str) {
	// NOTE: mb_convert_case() discards uppercase letters in words when converting
	// to title case. For example, it will convert "AAA" into "Aaa", which is
	// undesirable.

	$v = phutil_utf8v($str);
	$result = '';
	$last = null;

	$ord_a = ord('a');
	$ord_z = ord('z');
	foreach ($v as $c) {
	$convert = false;
	if ($last === null \|\| $last === ' ') {
	$o = ord($c[0]);
	if ($o >= $ord_a && $o <= $ord_z) {
	$convert = true;
	}
	}

	if ($convert) {
	$result .= phutil_utf8_strtoupper($c);
	} else {
	$result .= $c;
	}

	$last = $c;
	}

	return $result;
	}


	/**
	* Convert a string to lower case in a UTF8-aware way. Similar to
	* @{function:strtolower}.
	*
	* @param string UTF-8 input string.
	* @return string Input, in some semblance of lower case.
	*
	* @group utf8
	*
	* @phutil-external-symbol function mb_convert_case
	*/
	function phutil_utf8_strtolower($str) {
	if (function_exists('mb_convert_case')) {
	return mb_convert_case($str, MB_CASE_LOWER, 'UTF-8');
	}

	static $map;
	if ($map === null) {
	$map = array_combine(
	range('A', 'Z'),
	range('a', 'z'));
	}

	return phutil_utf8_strtr($str, $map);
	}


	/**
	* Convert a string to upper case in a UTF8-aware way. Similar to
	* @{function:strtoupper}.
	*
	* @param string UTF-8 input string.
	* @return string Input, in some semblance of upper case.
	*
	* @group utf8
	*
	* @phutil-external-symbol function mb_convert_case
	*/
	function phutil_utf8_strtoupper($str) {
	if (function_exists('mb_convert_case')) {
	return mb_convert_case($str, MB_CASE_UPPER, 'UTF-8');
	}

	static $map;
	if ($map === null) {
	$map = array_combine(
	range('a', 'z'),
	range('A', 'Z'));
	}

	return phutil_utf8_strtr($str, $map);
	}


	/**
	* Replace characters in a string in a UTF-aware way. Similar to
	* @{function:strtr}.
	*
	* @param string UTF-8 input string.
	* @param map<string, string> Map of characters to replace.
	* @return string Input with translated characters.
	*
	* @group utf8
	*/
	function phutil_utf8_strtr($str, array $map) {
	$v = phutil_utf8v($str);
	$result = '';
	foreach ($v as $c) {
	if (isset($map[$c])) {
	$result .= $map[$c];
	} else {
	$result .= $c;
	}
	}

	return $result;
	}

	/**
	* Determine if a given unicode character is a combining character or not.
	*
	* @param string A single unicode character.
	* @return boolean True or false.
	*
	* @group utf8
	*/

	function phutil_utf8_is_combining_character($character) {
	$components = phutil_utf8v_codepoints($character);

	// Combining Diacritical Marks (0300 - 036F).
	// Combining Diacritical Marks Supplement (1DC0 - 1DFF).
	// Combining Diacritical Marks for Symbols (20D0 - 20FF).
	// Combining Half Marks (FE20 - FE2F).

	foreach ($components as $codepoint) {
	if ($codepoint >= 0x0300 && $codepoint <= 0x036F \|\|
	$codepoint >= 0x1DC0 && $codepoint <= 0x1DFF \|\|
	$codepoint >= 0x20D0 && $codepoint <= 0x20FF \|\|
	$codepoint >= 0xFE20 && $codepoint <= 0xFE2F) {
	return true;
	}
	}

	return false;
	}

	/**
	* Split a UTF-8 string into an array of characters. Combining characters
	* are not split.
	*
	* @param string A valid utf-8 string.
	* @return list A list of characters in the string.
	*
	* @group utf8
	*/

	function phutil_utf8v_combined($string) {
	$components = phutil_utf8v($string);
	$array_length = count($components);

	// If the first character in the string is a combining character,
	// prepend a space to the string.
	if (
	$array_length > 0 &&
	phutil_utf8_is_combining_character($components[0])) {
	$string = " ".$string;
	$components = phutil_utf8v($string);
	$array_length++;
	}

	for ($index = 1; $index < $array_length; $index++) {
	if (phutil_utf8_is_combining_character($components[$index])) {
	$components[$index - 1] =
	$components[$index - 1].$components[$index];

	unset($components[$index]);
	$components = array_values($components);

	$index --;
	$array_length = count($components);
	}
	}

	return $components;
	}

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