/wp-includes/formatting.php

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<?php
/**
 * Main WordPress Formatting API.
 *
 * Handles many functions for formatting output.
 *
 * @package WordPress
 */

/**
 * Replaces common plain text characters into formatted entities
 *
 * As an example,
 * <code>
 * 'cause today's effort makes it worth tomorrow's "holiday"...
 * </code>
 * Becomes:
 * <code>
 * &#8217;cause today&#8217;s effort makes it worth tomorrow&#8217;s &#8220;holiday&#8221;&#8230;
 * </code>
 * Code within certain html blocks are skipped.
 *
 * @since 0.71
 * @uses $wp_cockneyreplace Array of formatted entities for certain common phrases
 *
 * @param string $text The text to be formatted
 * @return string The string replaced with html entities
 */
function wptexturize($text) {
	global $wp_cockneyreplace;
	static $static_characters, $static_replacements, $dynamic_characters, $dynamic_replacements,
		$default_no_texturize_tags, $default_no_texturize_shortcodes;

	// No need to set up these static variables more than once
	if ( ! isset( $static_characters ) ) {
		/* translators: opening curly double quote */
		$opening_quote = _x( '&#8220;', 'opening curly double quote' );
		/* translators: closing curly double quote */
		$closing_quote = _x( '&#8221;', 'closing curly double quote' );

		/* translators: apostrophe, for example in 'cause or can't */
		$apos = _x( '&#8217;', 'apostrophe' );

		/* translators: prime, for example in 9' (nine feet) */
		$prime = _x( '&#8242;', 'prime' );
		/* translators: double prime, for example in 9" (nine inches) */
		$double_prime = _x( '&#8243;', 'double prime' );

		/* translators: opening curly single quote */
		$opening_single_quote = _x( '&#8216;', 'opening curly single quote' );
		/* translators: closing curly single quote */
		$closing_single_quote = _x( '&#8217;', 'closing curly single quote' );

		/* translators: en dash */
		$en_dash = _x( '&#8211;', 'en dash' );
		/* translators: em dash */
		$em_dash = _x( '&#8212;', 'em dash' );

		$default_no_texturize_tags = array('pre', 'code', 'kbd', 'style', 'script', 'tt');
		$default_no_texturize_shortcodes = array('code');

		// if a plugin has provided an autocorrect array, use it
		if ( isset($wp_cockneyreplace) ) {
			$cockney = array_keys($wp_cockneyreplace);
			$cockneyreplace = array_values($wp_cockneyreplace);
		} elseif ( "'" != $apos ) { // Only bother if we're doing a replacement.
			$cockney = array( "'tain't", "'twere", "'twas", "'tis", "'twill", "'til", "'bout", "'nuff", "'round", "'cause" );
			$cockneyreplace = array( $apos . "tain" . $apos . "t", $apos . "twere", $apos . "twas", $apos . "tis", $apos . "twill", $apos . "til", $apos . "bout", $apos . "nuff", $apos . "round", $apos . "cause" );
		} else {
			$cockney = $cockneyreplace = array();
		}

		$static_characters = array_merge( array( '---', ' -- ', '--', ' - ', 'xn&#8211;', '...', '``', '\'\'', ' (tm)' ), $cockney );
		$static_replacements = array_merge( array( $em_dash, ' ' . $em_dash . ' ', $en_dash, ' ' . $en_dash . ' ', 'xn--', '&#8230;', $opening_quote, $closing_quote, ' &#8482;' ), $cockneyreplace );

		$dynamic = array();
		if ( "'" != $apos ) {
			$dynamic[ '/\'(\d\d(?:&#8217;|\')?s)/' ] = $apos . '$1'; // '99's
			$dynamic[ '/\'(\d)/'                   ] = $apos . '$1'; // '99
		}
		if ( "'" != $opening_single_quote )
			$dynamic[ '/(\s|\A|[([{<]|")\'/'       ] = '$1' . $opening_single_quote; // opening single quote, even after (, {, <, [
		if ( '"' != $double_prime )
			$dynamic[ '/(\d)"/'                    ] = '$1' . $double_prime; // 9" (double prime)
		if ( "'" != $prime )
			$dynamic[ '/(\d)\'/'                   ] = '$1' . $prime; // 9' (prime)
		if ( "'" != $apos )
			$dynamic[ '/(\S)\'([^\'\s])/'          ] = '$1' . $apos . '$2'; // apostrophe in a word
		if ( '"' != $opening_quote )
			$dynamic[ '/(\s|\A|[([{<])"(?!\s)/'    ] = '$1' . $opening_quote . '$2'; // opening double quote, even after (, {, <, [
		if ( '"' != $closing_quote )
			$dynamic[ '/"(\s|\S|\Z)/'              ] = $closing_quote . '$1'; // closing double quote
		if ( "'" != $closing_single_quote )
			$dynamic[ '/\'([\s.]|\Z)/'             ] = $closing_single_quote . '$1'; // closing single quote

		$dynamic[ '/\b(\d+)x(\d+)\b/'              ] = '$1&#215;$2'; // 9x9 (times)

		$dynamic_characters = array_keys( $dynamic );
		$dynamic_replacements = array_values( $dynamic );
	}

	// Transform into regexp sub-expression used in _wptexturize_pushpop_element
	// Must do this every time in case plugins use these filters in a context sensitive manner
	$no_texturize_tags = '(' . implode('|', apply_filters('no_texturize_tags', $default_no_texturize_tags) ) . ')';
	$no_texturize_shortcodes = '(' . implode('|', apply_filters('no_texturize_shortcodes', $default_no_texturize_shortcodes) ) . ')';

	$no_texturize_tags_stack = array();
	$no_texturize_shortcodes_stack = array();

	$textarr = preg_split('/(<.*>|\[.*\])/Us', $text, -1, PREG_SPLIT_DELIM_CAPTURE);

	foreach ( $textarr as &$curl ) {
		if ( empty( $curl ) )
			continue;

		// Only call _wptexturize_pushpop_element if first char is correct tag opening
		$first = $curl[0];
		if ( '<' === $first ) {
			_wptexturize_pushpop_element($curl, $no_texturize_tags_stack, $no_texturize_tags, '<', '>');
		} elseif ( '[' === $first ) {
			_wptexturize_pushpop_element($curl, $no_texturize_shortcodes_stack, $no_texturize_shortcodes, '[', ']');
		} elseif ( empty($no_texturize_shortcodes_stack) && empty($no_texturize_tags_stack) ) {
			// This is not a tag, nor is the texturization disabled static strings
			$curl = str_replace($static_characters, $static_replacements, $curl);
			// regular expressions
			$curl = preg_replace($dynamic_characters, $dynamic_replacements, $curl);
		}
		$curl = preg_replace('/&([^#])(?![a-zA-Z1-4]{1,8};)/', '&#038;$1', $curl);
	}
	return implode( '', $textarr );
}

/**
 * Search for disabled element tags. Push element to stack on tag open and pop
 * on tag close. Assumes first character of $text is tag opening.
 *
 * @since 2.9.0
 * @access private
 *
 * @param string $text Text to check. First character is assumed to be $opening
 * @param array $stack Array used as stack of opened tag elements
 * @param string $disabled_elements Tags to match against formatted as regexp sub-expression
 * @param string $opening Tag opening character, assumed to be 1 character long
 * @param string $closing Tag closing character
 */
function _wptexturize_pushpop_element($text, &$stack, $disabled_elements, $opening = '<', $closing = '>') {
	// Check if it is a closing tag -- otherwise assume opening tag
	if (strncmp($opening . '/', $text, 2)) {
		// Opening? Check $text+1 against disabled elements
		if (preg_match('/^' . $disabled_elements . '\b/', substr($text, 1), $matches)) {
			/*
			 * This disables texturize until we find a closing tag of our type
			 * (e.g. <pre>) even if there was invalid nesting before that
			 *
			 * Example: in the case <pre>sadsadasd</code>"baba"</pre>
			 *          "baba" won't be texturize
			 */

			array_push($stack, $matches[1]);
		}
	} else {
		// Closing? Check $text+2 against disabled elements
		$c = preg_quote($closing, '/');
		if (preg_match('/^' . $disabled_elements . $c . '/', substr($text, 2), $matches)) {
			$last = array_pop($stack);

			// Make sure it matches the opening tag
			if ($last != $matches[1])
				array_push($stack, $last);
		}
	}
}

/**
 * Replaces double line-breaks with paragraph elements.
 *
 * A group of regex replaces used to identify text formatted with newlines and
 * replace double line-breaks with HTML paragraph tags. The remaining
 * line-breaks after conversion become <<br />> tags, unless $br is set to '0'
 * or 'false'.
 *
 * @since 0.71
 *
 * @param string $pee The text which has to be formatted.
 * @param bool $br Optional. If set, this will convert all remaining line-breaks after paragraphing. Default true.
 * @return string Text which has been converted into correct paragraph tags.
 */
function wpautop($pee, $br = true) {
	$pre_tags = array();

	if ( trim($pee) === '' )
		return '';

	$pee = $pee . "\n"; // just to make things a little easier, pad the end

	if ( strpos($pee, '<pre') !== false ) {
		$pee_parts = explode( '</pre>', $pee );
		$last_pee = array_pop($pee_parts);
		$pee = '';
		$i = 0;

		foreach ( $pee_parts as $pee_part ) {
			$start = strpos($pee_part, '<pre');

			// Malformed html?
			if ( $start === false ) {
				$pee .= $pee_part;
				continue;
			}

			$name = "<pre wp-pre-tag-$i></pre>";
			$pre_tags[$name] = substr( $pee_part, $start ) . '</pre>';

			$pee .= substr( $pee_part, 0, $start ) . $name;
			$i++;
		}

		$pee .= $last_pee;
	}

	$pee = preg_replace('|<br />\s*<br />|', "\n\n", $pee);
	// Space things out a little
	$allblocks = '(?:table|thead|tfoot|caption|col|colgroup|tbody|tr|td|th|div|dl|dd|dt|ul|ol|li|pre|select|option|form|map|area|blockquote|address|math|style|p|h[1-6]|hr|fieldset|noscript|legend|section|article|aside|hgroup|header|footer|nav|figure|figcaption|details|menu|summary)';
	$pee = preg_replace('!(<' . $allblocks . '[^>]*>)!', "\n$1", $pee);
	$pee = preg_replace('!(</' . $allblocks . '>)!', "$1\n\n", $pee);
	$pee = str_replace(array("\r\n", "\r"), "\n", $pee); // cross-platform newlines
	if ( strpos($pee, '<object') !== false ) {
		$pee = preg_replace('|\s*<param([^>]*)>\s*|', "<param$1>", $pee); // no pee inside object/embed
		$pee = preg_replace('|\s*</embed>\s*|', '</embed>', $pee);
	}
	$pee = preg_replace("/\n\n+/", "\n\n", $pee); // take care of duplicates
	// make paragraphs, including one at the end
	$pees = preg_split('/\n\s*\n/', $pee, -1, PREG_SPLIT_NO_EMPTY);
	$pee = '';
	foreach ( $pees as $tinkle )
		$pee .= '<p>' . trim($tinkle, "\n") . "</p>\n";
	$pee = preg_replace('|<p>\s*</p>|', '', $pee); // under certain strange conditions it could create a P of entirely whitespace
	$pee = preg_replace('!<p>([^<]+)</(div|address|form)>!', "<p>$1</p></$2>", $pee);
	$pee = preg_replace('!<p>\s*(</?' . $allblocks . '[^>]*>)\s*</p>!', "$1", $pee); // don't pee all over a tag
	$pee = preg_replace("|<p>(<li.+?)</p>|", "$1", $pee); // problem with nested lists
	$pee = preg_replace('|<p><blockquote([^>]*)>|i', "<blockquote$1><p>", $pee);
	$pee = str_replace('</blockquote></p>', '</p></blockquote>', $pee);
	$pee = preg_replace('!<p>\s*(</?' . $allblocks . '[^>]*>)!', "$1", $pee);
	$pee = preg_replace('!(</?' . $allblocks . '[^>]*>)\s*</p>!', "$1", $pee);
	if ( $br ) {
		$pee = preg_replace_callback('/<(script|style).*?<\/\\1>/s', '_autop_newline_preservation_helper', $pee);
		$pee = preg_replace('|(?<!<br />)\s*\n|', "<br />\n", $pee); // optionally make line breaks
		$pee = str_replace('<WPPreserveNewline />', "\n", $pee);
	}
	$pee = preg_replace('!(</?' . $allblocks . '[^>]*>)\s*<br />!', "$1", $pee);
	$pee = preg_replace('!<br />(\s*</?(?:p|li|div|dl|dd|dt|th|pre|td|ul|ol)[^>]*>)!', '$1', $pee);
	$pee = preg_replace( "|\n</p>$|", '</p>', $pee );

	if ( !empty($pre_tags) )
		$pee = str_replace(array_keys($pre_tags), array_values($pre_tags), $pee);

	return $pee;
}

/**
 * Newline preservation help function for wpautop
 *
 * @since 3.1.0
 * @access private
 *
 * @param array $matches preg_replace_callback matches array
 * @return string
 */
function _autop_newline_preservation_helper( $matches ) {
	return str_replace("\n", "<WPPreserveNewline />", $matches[0]);
}

/**
 * Don't auto-p wrap shortcodes that stand alone
 *
 * Ensures that shortcodes are not wrapped in <<p>>...<</p>>.
 *
 * @since 2.9.0
 *
 * @param string $pee The content.
 * @return string The filtered content.
 */
function shortcode_unautop( $pee ) {
	global $shortcode_tags;

	if ( empty( $shortcode_tags ) || !is_array( $shortcode_tags ) ) {
		return $pee;
	}

	$tagregexp = join( '|', array_map( 'preg_quote', array_keys( $shortcode_tags ) ) );

	$pattern =
		  '/'
		. '<p>'                              // Opening paragraph
		. '\\s*+'                            // Optional leading whitespace
		. '('                                // 1: The shortcode
		.     '\\['                          // Opening bracket
		.     "($tagregexp)"                 // 2: Shortcode name
		.     '(?![\\w-])'                   // Not followed by word character or hyphen
		                                     // Unroll the loop: Inside the opening shortcode tag
		.     '[^\\]\\/]*'                   // Not a closing bracket or forward slash
		.     '(?:'
		.         '\\/(?!\\])'               // A forward slash not followed by a closing bracket
		.         '[^\\]\\/]*'               // Not a closing bracket or forward slash
		.     ')*?'
		.     '(?:'
		.         '\\/\\]'                   // Self closing tag and closing bracket
		.     '|'
		.         '\\]'                      // Closing bracket
		.         '(?:'                      // Unroll the loop: Optionally, anything between the opening and closing shortcode tags
		.             '[^\\[]*+'             // Not an opening bracket
		.             '(?:'
		.                 '\\[(?!\\/\\2\\])' // An opening bracket not followed by the closing shortcode tag
		.                 '[^\\[]*+'         // Not an opening bracket
		.             ')*+'
		.             '\\[\\/\\2\\]'         // Closing shortcode tag
		.         ')?'
		.     ')'
		. ')'
		. '\\s*+'                            // optional trailing whitespace
		. '<\\/p>'                           // closing paragraph
		. '/s';

	return preg_replace( $pattern, '$1', $pee );
}

/**
 * Checks to see if a string is utf8 encoded.
 *
 * NOTE: This function checks for 5-Byte sequences, UTF8
 *       has Bytes Sequences with a maximum length of 4.
 *
 * @author bmorel at ssi dot fr (modified)
 * @since 1.2.1
 *
 * @param string $str The string to be checked
 * @return bool True if $str fits a UTF-8 model, false otherwise.
 */
function seems_utf8($str) {
	$length = strlen($str);
	for ($i=0; $i < $length; $i++) {
		$c = ord($str[$i]);
		if ($c < 0x80) $n = 0; # 0bbbbbbb
		elseif (($c & 0xE0) == 0xC0) $n=1; # 110bbbbb
		elseif (($c & 0xF0) == 0xE0) $n=2; # 1110bbbb
		elseif (($c & 0xF8) == 0xF0) $n=3; # 11110bbb
		elseif (($c & 0xFC) == 0xF8) $n=4; # 111110bb
		elseif (($c & 0xFE) == 0xFC) $n=5; # 1111110b
		else return false; # Does not match any model
		for ($j=0; $j<$n; $j++) { # n bytes matching 10bbbbbb follow ?
			if ((++$i == $length) || ((ord($str[$i]) & 0xC0) != 0x80))
				return false;
		}
	}
	return true;
}

/**
 * Converts a number of special characters into their HTML entities.
 *
 * Specifically deals with: &, <, >, ", and '.
 *
 * $quote_style can be set to ENT_COMPAT to encode " to
 * &quot;, or ENT_QUOTES to do both. Default is ENT_NOQUOTES where no quotes are encoded.
 *
 * @since 1.2.2
 * @access private
 *
 * @param string $string The text which is to be encoded.
 * @param mixed $quote_style Optional. Converts double quotes if set to ENT_COMPAT, both single and double if set to ENT_QUOTES or none if set to ENT_NOQUOTES. Also compatible with old values; converting single quotes if set to 'single', double if set to 'double' or both if otherwise set. Default is ENT_NOQUOTES.
 * @param string $charset Optional. The character encoding of the string. Default is false.
 * @param boolean $double_encode Optional. Whether to encode existing html entities. Default is false.
 * @return string The encoded text with HTML entities.
 */
function _wp_specialchars( $string, $quote_style = ENT_NOQUOTES, $charset = false, $double_encode = false ) {
	$string = (string) $string;

	if ( 0 === strlen( $string ) )
		return '';

	// Don't bother if there are no specialchars - saves some processing
	if ( ! preg_match( '/[&<>"\']/', $string ) )
		return $string;

	// Account for the previous behaviour of the function when the $quote_style is not an accepted value
	if ( empty( $quote_style ) )
		$quote_style = ENT_NOQUOTES;
	elseif ( ! in_array( $quote_style, array( 0, 2, 3, 'single', 'double' ), true ) )
		$quote_style = ENT_QUOTES;

	// Store the site charset as a static to avoid multiple calls to wp_load_alloptions()
	if ( ! $charset ) {
		static $_charset;
		if ( ! isset( $_charset ) ) {
			$alloptions = wp_load_alloptions();
			$_charset = isset( $alloptions['blog_charset'] ) ? $alloptions['blog_charset'] : '';
		}
		$charset = $_charset;
	}

	if ( in_array( $charset, array( 'utf8', 'utf-8', 'UTF8' ) ) )
		$charset = 'UTF-8';

	$_quote_style = $quote_style;

	if ( $quote_style === 'double' ) {
		$quote_style = ENT_COMPAT;
		$_quote_style = ENT_COMPAT;
	} elseif ( $quote_style === 'single' ) {
		$quote_style = ENT_NOQUOTES;
	}

	// Handle double encoding ourselves
	if ( $double_encode ) {
		$string = @htmlspecialchars( $string, $quote_style, $charset );
	} else {
		// Decode &amp; into &
		$string = wp_specialchars_decode( $string, $_quote_style );

		// Guarantee every &entity; is valid or re-encode the &
		$string = wp_kses_normalize_entities( $string );

		// Now re-encode everything except &entity;
		$string = preg_split( '/(&#?x?[0-9a-z]+;)/i', $string, -1, PREG_SPLIT_DELIM_CAPTURE );

		for ( $i = 0; $i < count( $string ); $i += 2 )
			$string[$i] = @htmlspecialchars( $string[$i], $quote_style, $charset );

		$string = implode( '', $string );
	}

	// Backwards compatibility
	if ( 'single' === $_quote_style )
		$string = str_replace( "'", '&#039;', $string );

	return $string;
}

/**
 * Converts a number of HTML entities into their special characters.
 *
 * Specifically deals with: &, <, >, ", and '.
 *
 * $quote_style can be set to ENT_COMPAT to decode " entities,
 * or ENT_QUOTES to do both " and '. Default is ENT_NOQUOTES where no quotes are decoded.
 *
 * @since 2.8.0
 *
 * @param string $string The text which is to be decoded.
 * @param mixed $quote_style Optional. Converts double quotes if set to ENT_COMPAT, both single and double if set to ENT_QUOTES or none if set to ENT_NOQUOTES. Also compatible with old _wp_specialchars() values; converting single quotes if set to 'single', double if set to 'double' or both if otherwise set. Default is ENT_NOQUOTES.
 * @return string The decoded text without HTML entities.
 */
function wp_specialchars_decode( $string, $quote_style = ENT_NOQUOTES ) {
	$string = (string) $string;

	if ( 0 === strlen( $string ) ) {
		return '';
	}

	// Don't bother if there are no entities - saves a lot of processing
	if ( strpos( $string, '&' ) === false ) {
		return $string;
	}

	// Match the previous behaviour of _wp_specialchars() when the $quote_style is not an accepted value
	if ( empty( $quote_style ) ) {
		$quote_style = ENT_NOQUOTES;
	} elseif ( !in_array( $quote_style, array( 0, 2, 3, 'single', 'double' ), true ) ) {
		$quote_style = ENT_QUOTES;
	}

	// More complete than get_html_translation_table( HTML_SPECIALCHARS )
	$single = array( '&#039;'  => '\'', '&#x27;' => '\'' );
	$single_preg = array( '/&#0*39;/'  => '&#039;', '/&#x0*27;/i' => '&#x27;' );
	$double = array( '&quot;' => '"', '&#034;'  => '"', '&#x22;' => '"' );
	$double_preg = array( '/&#0*34;/'  => '&#034;', '/&#x0*22;/i' => '&#x22;' );
	$others = array( '&lt;'   => '<', '&#060;'  => '<', '&gt;'   => '>', '&#062;'  => '>', '&amp;'  => '&', '&#038;'  => '&', '&#x26;' => '&' );
	$others_preg = array( '/&#0*60;/'  => '&#060;', '/&#0*62;/'  => '&#062;', '/&#0*38;/'  => '&#038;', '/&#x0*26;/i' => '&#x26;' );

	if ( $quote_style === ENT_QUOTES ) {
		$translation = array_merge( $single, $double, $others );
		$translation_preg = array_merge( $single_preg, $double_preg, $others_preg );
	} elseif ( $quote_style === ENT_COMPAT || $quote_style === 'double' ) {
		$translation = array_merge( $double, $others );
		$translation_preg = array_merge( $double_preg, $others_preg );
	} elseif ( $quote_style === 'single' ) {
		$translation = array_merge( $single, $others );
		$translation_preg = array_merge( $single_preg, $others_preg );
	} elseif ( $quote_style === ENT_NOQUOTES ) {
		$translation = $others;
		$translation_preg = $others_preg;
	}

	// Remove zero padding on numeric entities
	$string = preg_replace( array_keys( $translation_preg ), array_values( $translation_preg ), $string );

	// Replace characters according to translation table
	return strtr( $string, $translation );
}

/**
 * Checks for invalid UTF8 in a string.
 *
 * @since 2.8.0
 *
 * @param string $string The text which is to be checked.
 * @param boolean $strip Optional. Whether to attempt to strip out invalid UTF8. Default is false.
 * @return string The checked text.
 */
function wp_check_invalid_utf8( $string, $strip = false ) {
	$string = (string) $string;

	if ( 0 === strlen( $string ) ) {
		return '';
	}

	// Store the site charset as a static to avoid multiple calls to get_option()
	static $is_utf8;
	if ( !isset( $is_utf8 ) ) {
		$is_utf8 = in_array( get_option( 'blog_charset' ), array( 'utf8', 'utf-8', 'UTF8', 'UTF-8' ) );
	}
	if ( !$is_utf8 ) {
		return $string;
	}

	// Check for support for utf8 in the installed PCRE library once and store the result in a static
	static $utf8_pcre;
	if ( !isset( $utf8_pcre ) ) {
		$utf8_pcre = @preg_match( '/^./u', 'a' );
	}
	// We can't demand utf8 in the PCRE installation, so just return the string in those cases
	if ( !$utf8_pcre ) {
		return $string;
	}

	// preg_match fails when it encounters invalid UTF8 in $string
	if ( 1 === @preg_match( '/^./us', $string ) ) {
		return $string;
	}

	// Attempt to strip the bad chars if requested (not recommended)
	if ( $strip && function_exists( 'iconv' ) ) {
		return iconv( 'utf-8', 'utf-8', $string );
	}

	return '';
}

/**
 * Encode the Unicode values to be used in the URI.
 *
 * @since 1.5.0
 *
 * @param string $utf8_string
 * @param int $length Max length of the string
 * @return string String with Unicode encoded for URI.
 */
function utf8_uri_encode( $utf8_string, $length = 0 ) {
	$unicode = '';
	$values = array();
	$num_octets = 1;
	$unicode_length = 0;

	$string_length = strlen( $utf8_string );
	for ($i = 0; $i < $string_length; $i++ ) {

		$value = ord( $utf8_string[ $i ] );

		if ( $value < 128 ) {
			if ( $length && ( $unicode_length >= $length ) )
				break;
			$unicode .= chr($value);
			$unicode_length++;
		} else {
			if ( count( $values ) == 0 ) $num_octets = ( $value < 224 ) ? 2 : 3;

			$values[] = $value;

			if ( $length && ( $unicode_length + ($num_octets * 3) ) > $length )
				break;
			if ( count( $values ) == $num_octets ) {
				if ($num_octets == 3) {
					$unicode .= '%' . dechex($values[0]) . '%' . dechex($values[1]) . '%' . dechex($values[2]);
					$unicode_length += 9;
				} else {
					$unicode .= '%' . dechex($values[0]) . '%' . dechex($values[1]);
					$unicode_length += 6;
				}

				$values = array();
				$num_octets = 1;
			}
		}
	}

	return $unicode;
}

/**
 * Converts all accent characters to ASCII characters.
 *
 * If there are no accent characters, then the string given is just returned.
 *
 * @since 1.2.1
 *
 * @param string $string Text that might have accent characters
 * @return string Filtered string with replaced "nice" characters.
 */
function remove_accents($string) {
	if ( !preg_match('/[\x80-\xff]/', $string) )
		return $string;

	if (seems_utf8($string)) {
		$chars = array(
		// Decompositions for Latin-1 Supplement
		chr(194).chr(170) => 'a', chr(194).chr(186) => 'o',
		chr(195).chr(128) => 'A', chr(195).chr(129) => 'A',
		chr(195).chr(130) => 'A', chr(195).chr(131) => 'A',
		chr(195).chr(132) => 'A', chr(195).chr(133) => 'A',
		chr(195).chr(134) => 'AE',chr(195).chr(135) => 'C',
		chr(195).chr(136) => 'E', chr(195).chr(137) => 'E',
		chr(195).chr(138) => 'E', chr(195).chr(139) => 'E',
		chr(195).chr(140) => 'I', chr(195).chr(141) => 'I',
		chr(195).chr(142) => 'I', chr(195).chr(143) => 'I',
		chr(195).chr(144) => 'D', chr(195).chr(145) => 'N',
		chr(195).chr(146) => 'O', chr(195).chr(147) => 'O',
		chr(195).chr(148) => 'O', chr(195).chr(149) => 'O',
		chr(195).chr(150) => 'O', chr(195).chr(153) => 'U',
		chr(195).chr(154) => 'U', chr(195).chr(155) => 'U',
		chr(195).chr(156) => 'U', chr(195).chr(157) => 'Y',
		chr(195).chr(158) => 'TH',chr(195).chr(159) => 's',
		chr(195).chr(160) => 'a', chr(195).chr(161) => 'a',
		chr(195).chr(162) => 'a', chr(195).chr(163) => 'a',
		chr(195).chr(164) => 'a', chr(195).chr(165) => 'a',
		chr(195).chr(166) => 'ae',chr(195).chr(167) => 'c',
		chr(195).chr(168) => 'e', chr(195).chr(169) => 'e',
		chr(195).chr(170) => 'e', chr(195).chr(171) => 'e',
		chr(195).chr(172) => 'i', chr(195).chr(173) => 'i',
		chr(195).chr(174) => 'i', chr(195).chr(175) => 'i',
		chr(195).chr(176) => 'd', chr(195).chr(177) => 'n',
		chr(195).chr(178) => 'o', chr(195).chr(179) => 'o',
		chr(195).chr(180) => 'o', chr(195).chr(181) => 'o',
		chr(195).chr(182) => 'o', chr(195).chr(184) => 'o',
		chr(195).chr(185) => 'u', chr(195).chr(186) => 'u',
		chr(195).chr(187) => 'u', chr(195).chr(188) => 'u',
		chr(195).chr(189) => 'y', chr(195).chr(190) => 'th',
		chr(195).chr(191) => 'y', chr(195).chr(152) => 'O',
		// Decompositions for Latin Extended-A
		chr(196).chr(128) => 'A', chr(196).chr(129) => 'a',
		chr(196).chr(130) => 'A', chr(196).chr(131) => 'a',
		chr(196).chr(132) => 'A', chr(196).chr(133) => 'a',
		chr(196).chr(134) => 'C', chr(196).chr(135) => 'c',
		chr(196).chr(136) => 'C', chr(196).chr(137) => 'c',
		chr(196).chr(138) => 'C', chr(196).chr(139) => 'c',
		chr(196).chr(140) => 'C', chr(196).chr(141) => 'c',
		chr(196).chr(142) => 'D', chr(196).chr(143) => 'd',
		chr(196).chr(144) => 'D', chr(196).chr(145) => 'd',
		chr(196).chr(146) => 'E', chr(196).chr(147) => 'e',
		chr(196).chr(148) => 'E', chr(196).chr(149) => 'e',
		chr(196).chr(150) => 'E', chr(196).chr(151) => 'e',
		chr(196).chr(152) => 'E', chr(196).chr(153) => 'e',
		chr(196).chr(154) => 'E', chr(196).chr(155) => 'e',
		chr(196).chr(156) => 'G', chr(196).chr(157) => 'g',
		chr(196).chr(158) => 'G', chr(196).chr(159) => 'g',
		chr(196).chr(160) => 'G', chr(196).chr(161) => 'g',
		chr(196).chr(162) => 'G', chr(196).chr(163) => 'g',
		chr(196).chr(164) => 'H', chr(196).chr(165) => 'h',
		chr(196).chr(166) => 'H', chr(196).chr(167) => 'h',
		chr(196).chr(168) => 'I', chr(196).chr(169) => 'i',
		chr(196).chr(170) => 'I', chr(196).chr(171) => 'i',
		chr(196).chr(172) => 'I', chr(196).chr(173) => 'i',
		chr(196).chr(174) => 'I', chr(196).chr(175) => 'i',
		chr(196).chr(176) => 'I', chr(196).chr(177) => 'i',
		chr(196).chr(178) => 'IJ',chr(196).chr(179) => 'ij',
		chr(196).chr(180) => 'J', chr(196).chr(181) => 'j',
		chr(196).chr(182) => 'K', chr(196).chr(183) => 'k',
		chr(196).chr(184) => 'k', chr(196).chr(185) => 'L',
		chr(196).chr(186) => 'l', chr(196).chr(187) => 'L',
		chr(196).chr(188) => 'l', chr(196).chr(189) => 'L',
		chr(196).chr(190) => 'l', chr(196).chr(191) => 'L',
		chr(197).chr(128) => 'l', chr(197).chr(129) => 'L',
		chr(197).chr(130) => 'l', chr(197).chr(131) => 'N',
		chr(197).chr(132) => 'n', chr(197).chr(133) => 'N',
		chr(197).chr(134) => 'n', chr(197).chr(135) => 'N',
		chr(197).chr(136) => 'n', chr(197).chr(137) => 'N',
		chr(197).chr(138) => 'n', chr(197).chr(139) => 'N',
		chr(197).chr(140) => 'O', chr(197).chr(141) => 'o',
		chr(197).chr(142) => 'O', chr(197).chr(143) => 'o',
		chr(197).chr(144) => 'O', chr(197).chr(145) => 'o',
		chr(197).chr(146) => 'OE',chr(197).chr(147) => 'oe',
		chr(197).chr(148) => 'R',chr(197).chr(149) => 'r',
		chr(197).chr(150) => 'R',chr(197).chr(151) => 'r',
		chr(197).chr(152) => 'R',chr(197).chr(153) => 'r',
		chr(197).chr(154) => 'S',chr(197).chr(155) => 's',
		chr(197).chr(156) => 'S',chr(197).chr(157) => 's',
		chr(197).chr(158) => 'S',chr(197).chr(159) => 's',
		chr(197).chr(160) => 'S', chr(197).chr(161) => 's',
		chr(197).chr(162) => 'T', chr(197).chr(163) => 't',
		chr(197).chr(164) => 'T', chr(197).chr(165) => 't',
		chr(197).chr(166) => 'T', chr(197).chr(167) => 't',
		chr(197).chr(168) => 'U', chr(197).chr(169) => 'u',
		chr(197).chr(170) => 'U', chr(197).chr(171) => 'u',
		chr(197).chr(172) => 'U', chr(197).chr(173) => 'u',
		chr(197).chr(174) => 'U', chr(197).chr(175) => 'u',
		chr(197).chr(176) => 'U', chr(197).chr(177) => 'u',
		chr(197).chr(178) => 'U', chr(197).chr(179) => 'u',
		chr(197).chr(180) => 'W', chr(197).chr(181) => 'w',
		chr(197).chr(182) => 'Y', chr(197).chr(183) => 'y',
		chr(197).chr(184) => 'Y', chr(197).chr(185) => 'Z',
		chr(197).chr(186) => 'z', chr(197).chr(187) => 'Z',
		chr(197).chr(188) => 'z', chr(197).chr(189) => 'Z',
		chr(197).chr(190) => 'z', chr(197).chr(191) => 's',
		// Decompositions for Latin Extended-B
		chr(200).chr(152) => 'S', chr(200).chr(153) => 's',
		chr(200).chr(154) => 'T', chr(200).chr(155) => 't',
		// Euro Sign
		chr(226).chr(130).chr(172) => 'E',
		// GBP (Pound) Sign
		chr(194).chr(163) => '',
		// Vowels with diacritic (Vietnamese)
		// unmarked
		chr(198).chr(160) => 'O', chr(198).chr(161) => 'o',
		chr(198).chr(175) => 'U', chr(198).chr(176) => 'u',
		// grave accent
		chr(225).chr(186).chr(166) => 'A', chr(225).chr(186).chr(167) => 'a',
		chr(225).chr(186).chr(176) => 'A', chr(225).chr(186).chr(177) => 'a',
		chr(225).chr(187).chr(128) => 'E', chr(225).chr(187).chr(129) => 'e',
		chr(225).chr(187).chr(146) => 'O', chr(225).chr(187).chr(147) => 'o',
		chr(225).chr(187).chr(156) => 'O', chr(225).chr(187).chr(157) => 'o',
		chr(225).chr(187).chr(170) => 'U', chr(225).chr(187).chr(171) => 'u',
		chr(225).chr(187).chr(178) => 'Y', chr(225).chr(187).chr(179) => 'y',
		// hook
		chr(225).chr(186).chr(162) => 'A', chr(225).chr(186).chr(163) => 'a',
		chr(225).chr(186).chr(168) => 'A', chr(225).chr(186).chr(169) => 'a',
		chr(225).chr(186).chr(178) => 'A', chr(225).chr(186).chr(179) => 'a',
		chr(225).chr(186).chr(186) => 'E', chr(225).chr(186).chr(187) => 'e',
		chr(225).chr(187).chr(130) => 'E', chr(225).chr(187).chr(131) => 'e',
		chr(225).chr(187).chr(136) => 'I', chr(225).chr(187).chr(137) => 'i',
		chr(225).chr(187).chr(142) => 'O', chr(225).chr(187).chr(143) => 'o',
		chr(225).chr(187).chr(148) => 'O', chr(225).chr(187).chr(149) => 'o',
		chr(225).chr(187).chr(158) => 'O', chr(225).chr(187).chr(159) => 'o',
		chr(225).chr(187).chr(166) => 'U', chr(225).chr(187).chr(167) => 'u',
		chr(225).chr(187).chr(172) => 'U', chr(225).chr(187).chr(173) => 'u',
		chr(225).chr(187).chr(182) => 'Y', chr(225).chr(187).chr(183) => 'y',
		// tilde
		chr(225).chr(186).chr(170) => 'A', chr(225).chr(186).chr(171) => 'a',
		chr(225).chr(186).chr(180) => 'A', chr(225).chr(186).chr(181) => 'a',
		chr(225).chr(186).chr(188) => 'E', chr(225).chr(186).chr(189) => 'e',
		chr(225).chr(187).chr(132) => 'E', chr(225).chr(187).chr(133) => 'e',
		chr(225).chr(187).chr(150) => 'O', chr(225).chr(187).chr(151) => 'o',
		chr(225).chr(187).chr(160) => 'O', chr(225).chr(187).chr(161) => 'o',
		chr(225).chr(187).chr(174) => 'U', chr(225).chr(187).chr(175) => 'u',
		chr(225).chr(187).chr(184) => 'Y', chr(225).chr(187).chr(185) => 'y',
		// acute accent
		chr(225).chr(186).chr(164) => 'A', chr(225).chr(186).chr(165) => 'a',
		chr(225).chr(186).chr(174) => 'A', chr(225).chr(186).chr(175) => 'a',
		chr(225).chr(186).chr(190) => 'E', chr(225).chr(186).chr(191) => 'e',
		chr(225).chr(187).chr(144) => 'O', chr(225).chr(187).chr(145) => 'o',
		chr(225).chr(187).chr(154) => 'O', chr(225).chr(187).chr(155) => 'o',
		chr(225).chr(187).chr(168) => 'U', chr(225).chr(187).chr(169) => 'u',
		// dot below
		chr(225).chr(186).chr(160) => 'A', chr(225).chr(186).chr(161) => 'a',
		chr(225).chr(186).chr(172) => 'A', chr(225).chr(186).chr(173) => 'a',
		chr(225).chr(186).chr(182) => 'A', chr(225).chr(186).chr(183) => 'a',
		chr(225).chr(186).chr(184) => 'E', chr(225).chr(186).chr(185) => 'e',
		chr(225).chr(187).chr(134) => 'E', chr(225).chr(187).chr(135) => 'e',
		chr(225).chr(187).chr(138) => 'I', chr(225).chr(187).chr(139) => 'i',
		chr(225).chr(187).chr(140) => 'O', chr(225).chr(187).chr(141) => 'o',
		chr(225).chr(187).chr(152) => 'O', chr(225).chr(187).chr(153) => 'o',
		chr(225).chr(187).chr(162) => 'O', chr(225).chr(187).chr(163) => 'o',
		chr(225).chr(187).chr(164) => 'U', chr(225).chr(187).chr(165) => 'u',
		chr(225).chr(187).chr(176) => 'U', chr(225).chr(187).chr(177) => 'u',
		chr(225).chr(187).chr(180) => 'Y', chr(225).chr(187).chr(181) => 'y',
		// Vowels with diacritic (Chinese, Hanyu Pinyin)
		chr(201).chr(145) => 'a',
		// macron
		chr(199).chr(149) => 'U', chr(199).chr(150) => 'u',
		// acute accent
		chr(199).chr(151) => 'U', chr(199).chr(152) => 'u',
		// caron
		chr(199).chr(141) => 'A', chr(199).chr(142) => 'a',
		chr(199).chr(143) => 'I', chr(199).chr(144) => 'i',
		chr(199).chr(145) => 'O', chr(199).chr(146) => 'o',
		chr(199).chr(147) => 'U', chr(199).chr(148) => 'u',
		chr(199).chr(153) => 'U', chr(199).chr(154) => 'u',
		// grave accent
		chr(199).chr(155) => 'U', chr(199).chr(156) => 'u',
		);

		// Used for locale-specific rules
		$locale = get_locale();

		if ( 'de_DE' == $locale ) {
			$chars[ chr(195).chr(132) ] = 'Ae';
			$chars[ chr(195).chr(164) ] = 'ae';
			$chars[ chr(195).chr(150) ] = 'Oe';
			$chars[ chr(195).chr(182) ] = 'oe';
			$chars[ chr(195).chr(156) ] = 'Ue';
			$chars[ chr(195).chr(188) ] = 'ue';
			$chars[ chr(195).chr(159) ] = 'ss';
		}

		$string = strtr($string, $chars);
	} else {
		// Assume ISO-8859-1 if not UTF-8
		$chars['in'] = chr(128).chr(131).chr(138).chr(142).chr(154).chr(158)
			.chr(159).chr(162).chr(165).chr(181).chr(192).chr(193).chr(194)
			.chr(195).chr(196).chr(197).chr(199).chr(200).chr(201).chr(202)
			.chr(203).chr(204).chr(205).chr(206).chr(207).chr(209).chr(210)
			.chr(211).chr(212).chr(213).chr(214).chr(216).chr(217).chr(218)
			.chr(219).chr(220).chr(221).chr(224).chr(225).chr(226).chr(227)
			.chr(228).chr(229).chr(231).chr(232).chr(233).chr(234).chr(235)
			.chr(236).chr(237).chr(238).chr(239).chr(241).chr(242).chr(243)
			.chr(244).chr(245).chr(246).chr(248).chr(249).chr(250).chr(251)
			.chr(252).chr(253).chr(255);

		$chars['out'] = "EfSZszYcYuAAAAAACEEEEIIIINOOOOOOUUUUYaaaaaaceeeeiiiinoooooouuuuyy";

		$string = strtr($string, $chars['in'], $chars['out']);
		$double_chars['in'] = array(chr(140), chr(156), chr(198), chr(208), chr(222), chr(223), chr(230), chr(240), chr(254));
		$double_chars['out'] = array('OE', 'oe', 'AE', 'DH', 'TH', 'ss', 'ae', 'dh', 'th');
		$string = str_replace($double_chars['in'], $double_chars['out'], $string);
	}

	return $string;
}

/**
 * Sanitizes a filename, replacing whitespace with dashes.
 *
 * Removes special characters that are illegal in filenames on certain
 * operating systems and special characters requiring special escaping
 * to manipulate at the command line. Replaces spaces and consecutive
 * dashes with a single dash. Trims period, dash and underscore from beginning
 * and end of filename.
 *
 * @since 2.1.0
 *
 * @param string $filename The filename to be sanitized
 * @return string The sanitized filename
 */
function sanitize_file_name( $filename ) {
	$filename_raw = $filename;
	$special_chars = array("?", "[", "]", "/", "\\", "=", "<", ">", ":", ";", ",", "'", "\"", "&", "$", "#", "*", "(", ")", "|", "~", "`", "!", "{", "}", chr(0));
	$special_chars = apply_filters('sanitize_file_name_chars', $special_chars, $filename_raw);
	$filename = str_replace($special_chars, '', $filename);
	$filename = preg_replace('/[\s-]+/', '-', $filename);
	$filename = trim($filename, '.-_');

	// Split the filename into a base and extension[s]
	$parts = explode('.', $filename);

	// Return if only one extension
	if ( count($parts) <= 2 )
		return apply_filters('sanitize_file_name', $filename, $filename_raw);

	// Process multiple extensions
	$filename = array_shift($parts);
	$extension = array_pop($parts);
	$mimes = get_allowed_mime_types();

	// Loop over any intermediate extensions. Munge them with a trailing underscore if they are a 2 - 5 character
	// long alpha string not in the extension whitelist.
	foreach ( (array) $parts as $part) {
		$filename .= '.' . $part;

		if ( preg_match("/^[a-zA-Z]{2,5}\d?$/", $part) ) {
			$allowed = false;
			foreach ( $mimes as $ext_preg => $mime_match ) {
				$ext_preg = '!^(' . $ext_preg . ')$!i';
				if ( preg_match( $ext_preg, $part ) ) {
					$allowed = true;
					break;
				}
			}
			if ( !$allowed )
				$filename .= '_';
		}
	}
	$filename .= '.' . $extension;

	return apply_filters('sanitize_file_name', $filename, $filename_raw);
}

/**
 * Sanitizes a username, stripping out unsafe characters.
 *
 * Removes tags, octets, entities, and if strict is enabled, will only keep
 * alphanumeric, _, space, ., -, @. After sanitizing, it passes the username,
 * raw username (the username in the parameter), and the value of $strict as
 * parameters for the 'sanitize_user' filter.
 *
 * @since 2.0.0
 * @uses apply_filters() Calls 'sanitize_user' hook on username, raw username,
 *		and $strict parameter.
 *
 * @param string $username The username to be sanitized.
 * @param bool $strict If set limits $username to specific characters. Default false.
 * @return string The sanitized username, after passing through filters.
 */
function sanitize_user( $username, $strict = false ) {
	$raw_username = $username;
	$username = wp_strip_all_tags( $username );
	$username = remove_accents( $username );
	// Kill octets
	$username = preg_replace( '|%([a-fA-F0-9][a-fA-F0-9])|', '', $username );
	$username = preg_replace( '/&.+?;/', '', $username ); // Kill entities

	// If strict, reduce to ASCII for max portability.
	if ( $strict )
		$username = preg_replace( '|[^a-z0-9 _.\-@]|i', '', $username );

	$username = trim( $username );
	// Consolidate contiguous whitespace
	$username = preg_replace( '|\s+|', ' ', $username );

	return apply_filters( 'sanitize_user', $username, $raw_username, $strict );
}

/**
 * Sanitizes a string key.
 *
 * Keys are used as internal identifiers. Lowercase alphanumeric characters, dashes and underscores are allowed.
 *
 * @since 3.0.0
 *
 * @param string $key String key
 * @return string Sanitized key
 */
function sanitize_key( $key ) {
	$raw_key = $key;
	$key = strtolower( $key );
	$key = preg_replace( '/[^a-z0-9_\-]/', '', $key );
	return apply_filters( 'sanitize_key', $key, $raw_key );
}

/**
 * Sanitizes a title, or returns a fallback title.
 *
 * Specifically, HTML and PHP tags are stripped. Further actions can be added
 * via the plugin API. If $title is empty and $fallback_title is set, the latter
 * will be used.
 *
 * @since 1.0.0
 *
 * @param string $title The string to be sanitized.
 * @param string $fallback_title Optional. A title to use if $title is empty.
 * @param string $context Optional. The operation for which the string is sanitized
 * @return string The sanitized string.
 */
function sanitize_title( $title, $fallback_title = '', $context = 'save' ) {
	$raw_title = $title;

	if ( 'save' == $context )
		$title = remove_accents($title);

	$title = apply_filters('sanitize_title', $title, $raw_title, $context);

	if ( '' === $title || false === $title )
		$title = $fallback_title;

	return $title;
}

/**
 * Sanitizes a title with the 'query' context.
 *
 * Used for querying the database for a value from URL.
 *
 * @since 3.1.0
 * @uses sanitize_title()
 *
 * @param string $title The string to be sanitized.
 * @return string The sanitized string.
 */
function sanitize_title_for_query( $title ) {
	return sanitize_title( $title, '', 'query' );
}

/**
 * Sanitizes a title, replacing whitespace and a few other characters with dashes.
 *
 * Limits the output to alphanumeric characters, underscore (_) and dash (-).
 * Whitespace becomes a dash.
 *
 * @since 1.2.0
 *
 * @param string $title The title to be sanitized.
 * @param string $raw_title Optional. Not used.
 * @param string $context Optional. The operation for which the string is sanitized.
 * @return string The sanitized title.
 */
function sanitize_title_with_dashes( $title, $raw_title = '', $context = 'display' ) {
	$title = strip_tags($title);
	// Preserve escaped octets.
	$title = preg_replace('|%([a-fA-F0-9][a-fA-F0-9])|', '---$1---', $title);
	// Remove percent signs that are not part of an octet.
	$title = str_replace('%', '', $title);
	// Restore octets.
	$title = preg_replace('|---([a-fA-F0-9][a-fA-F0-9])---|', '%$1', $title);

	if (seems_utf8($title)) {
		if (function_exists('mb_strtolower')) {
			$title = mb_strtolower($title, 'UTF-8');
		}
		$title = utf8_uri_encode($title, 200);
	}

	$title = strtolower($title);
	$title = preg_replace('/&.+?;/', '', $title); // kill entities
	$title = str_replace('.', '-', $title);

	if ( 'save' == $context ) {
		// Convert nbsp, ndash and mdash to hyphens
		$title = str_replace( array( '%c2%a0', '%e2%80%93', '%e2%80%94' ), '-', $title );

		// Strip these characters entirely
		$title = str_replace( array(
			// iexcl and iquest
			'%c2%a1', '%c2%bf',
			// angle quotes
			'%c2%ab', '%c2%bb', '%e2%80%b9', '%e2%80%ba',
			// curly quotes
			'%e2%80%98', '%e2%80%99', '%e2%80%9c', '%e2%80%9d',
			'%e2%80%9a', '%e2%80%9b', '%e2%80%9e', '%e2%80%9f',
			// copy, reg, deg, hellip and trade
			'%c2%a9', '%c2%ae', '%c2%b0', '%e2%80%a6', '%e2%84%a2',
			// acute accents
			'%c2%b4', '%cb%8a', '%cc%81', '%cd%81',
			// grave accent, macron, caron
			'%cc%80', '%cc%84', '%cc%8c',
		), '', $title );

		// Convert times to x
		$title = str_replace( '%c3%97', 'x', $title );
	}

	$title = preg_replace('/[^%a-z0-9 _-]/', '', $title);
	$title = preg_replace('/\s+/', '-', $title);
	$title = preg_replace('|-+|', '-', $title);
	$title = trim($title, '-');

	return $title;
}

/**
 * Ensures a string is a valid SQL order by clause.
 *
 * Accepts one or more columns, with or without ASC/DESC, and also accepts
 * RAND().
 *
 * @since 2.5.1
 *
 * @param string $orderby Order by string to be checked.
 * @return string|bool Returns the order by clause if it is a match, false otherwise.
 */
function sanitize_sql_orderby( $orderby ){
	preg_match('/^\s*([a-z0-9_]+(\s+(ASC|DESC))?(\s*,\s*|\s*$))+|^\s*RAND\(\s*\)\s*$/i', $orderby, $obmatches);
	if ( !$obmatches )
		return false;
	return $orderby;
}

/**
 * Sanitizes an HTML classname to ensure it only contains valid characters.
 *
 * Strips the string down to A-Z,a-z,0-9,_,-. If this results in an empty
 * string then it will return the alternative value supplied.
 *
 * @todo Expand to support the full range of CDATA that a class attribute can contain.
 *
 * @since 2.8.0
 *
 * @param string $class The classname to be sanitized
 * @param string $fallback Optional. The value to return if the sanitization end's up as an empty string.
 * 	Defaults to an empty string.
 * @return string The sanitized value
 */
function sanitize_html_class( $class, $fallback = '' ) {
	//Strip out any % encoded octets
	$sanitized = preg_replace( '|%[a-fA-F0-9][a-fA-F0-9]|', '', $class );

	//Limit to A-Z,a-z,0-9,_,-
	$sanitized = preg_replace( '/[^A-Za-z0-9_-]/', '', $sanitized );

	if ( '' == $sanitized )
		$sanitized = $fallback;

	return apply_filters( 'sanitize_html_class', $sanitized, $class, $fallback );
}

/**
 * Converts a number of characters from a string.
 *
 * Metadata tags <<title>> and <<category>> are removed, <<br>> and <<hr>> are
 * converted into correct XHTML and Unicode characters are converted to the
 * valid range.
 *
 * @since 0.71
 *
 * @param string $content String of characters to be converted.
 * @param string $deprecated Not used.
 * @return string Converted string.
 */
function convert_chars($content, $deprecated = '') {
	if ( !empty( $deprecated ) )
		_deprecated_argument( __FUNCTION__, '0.71' );

	// Translation of invalid Unicode references range to valid range
	$wp_htmltranswinuni = array(
	'&#128;' => '&#8364;', // the Euro sign
	'&#129;' => '',
	'&#130;' => '&#8218;', // these are Windows CP1252 specific characters
	'&#131;' => '&#402;',  // they would look weird on non-Windows browsers
	'&#132;' => '&#8222;',
	'&#133;' => '&#8230;',
	'&#134;' => '&#8224;',
	'&#135;' => '&#8225;',
	'&#136;' => '&#710;',
	'&#137;' => '&#8240;',
	'&#138;' => '&#352;',
	'&#139;' => '&#8249;',
	'&#140;' => '&#338;',
	'&#141;' => '',
	'&#142;' => '&#381;',
	'&#143;' => '',
	'&#144;' => '',
	'&#145;' => '&#8216;',
	'&#146;' => '&#8217;',
	'&#147;' => '&#8220;',
	'&#148;' => '&#8221;',
	'&#149;' => '&#8226;',
	'&#150;' => '&#8211;',
	'&#151;' => '&#8212;',
	'&#152;' => '&#732;',
	'&#153;' => '&#8482;',
	'&#154;' => '&#353;',
	'&#155;' => '&#8250;',
	'&#156;' => '&#339;',
	'&#157;' => '',
	'&#158;' => '&#382;',
	'&#159;' => '&#376;'
	);

	// Remove metadata tags
	$content = preg_replace('/<title>(.+?)<\/title>/','',$content);
	$content = preg_replace('/<category>(.+?)<\/category>/','',$content);

	// Converts lone & characters into &#38; (a.k.a. &amp;)
	$content = preg_replace('/&([^#])(?![a-z1-4]{1,8};)/i', '&#038;$1', $content);

	// Fix Word pasting
	$content = strtr($content, $wp_htmltranswinuni);

	// Just a little XHTML help
	$content = str_replace('<br>', '<br />', $content);
	$content = str_replace('<hr>', '<hr />', $content);

	return $content;
}

/**
 * Balances tags if forced to, or if the 'use_balanceTags' option is set to true.
 *
 * @since 0.71
 *
 * @param string $text Text to be balanced
 * @param bool $force If true, forces balancing, ignoring the value of the option. Default false.
 * @return string Balanced text
 */
function balanceTags( $text, $force = false ) {
	if ( $force || get_option('use_balanceTags') == 1 )
		return force_balance_tags( $text );
	else
		return $text;
}

/**
 * Balances tags of string using a modified stack.
 *
 * @since 2.0.4
 *
 * @author Leonard Lin <leonard@acm.org>
 * @license GPL
 * @copyright November 4, 2001
 * @version 1.1
 * @todo Make better - change loop condition to $text in 1.2
 * @internal Modified by Scott Reilly (coffee2code) 02 Aug 2004
 *		1.1  Fixed handling of append/stack pop order of end text
 *			 Added Cleaning Hooks
 *		1.0  First Version
 *
 * @param string $text Text to be balanced.
 * @return string Balanced text.
 */
function force_balance_tags( $text ) {
	$tagstack = array();
	$stacksize = 0;
	$tagqueue = '';
	$newtext = '';
	// Known single-entity/self-closing tags
	$single_tags = array( 'area', 'base', 'basefont', 'br', 'col', 'command', 'embed', 'frame', 'hr', 'img', 'input', 'isindex', 'link', 'meta', 'param', 'source' );
	// Tags that can be immediately nested within themselves
	$nestable_tags = array( 'blockquote', 'div', 'object', 'q', 'span' );

	// WP bug fix for comments - in case you REALLY meant to type '< !--'
	$text = str_replace('< !--', '<    !--', $text);
	// WP bug fix for LOVE <3 (and other situations with '<' before a number)
	$text = preg_replace('#<([0-9]{1})#', '&lt;$1', $text);

	while ( preg_match("/<(\/?[\w:]*)\s*([^>]*)>/", $text, $regex) ) {
		$newtext .= $tagqueue;

		$i = strpos($text, $regex[0]);
		$l = strlen($regex[0]);

		// clear the shifter
		$tagqueue = '';
		// Pop or Push
		if ( isset($regex[1][0]) && '/' == $regex[1][0] ) { // End Tag
			$tag = strtolower(substr($regex[1],1));
			// if too many closing tags
			if( $stacksize <= 0 ) {
				$tag = '';
				// or close to be safe $tag = '/' . $tag;
			}
			// if stacktop value = tag close value then pop
			else if ( $tagstack[$stacksize - 1] == $tag ) { // found closing tag
				$tag = '</' . $tag . '>'; // Close Tag
				// Pop
				array_pop( $tagstack );
				$stacksize--;
			} else { // closing tag not at top, search for it
				for ( $j = $stacksize-1; $j >= 0; $j-- ) {
					if ( $tagstack[$j] == $tag ) {
					// add tag to tagqueue
						for ( $k = $stacksize-1; $k >= $j; $k--) {
							$tagqueue .= '</' . array_pop( $tagstack ) . '>';
							$stacksize--;
						}
						break;
					}
				}
				$tag = '';
			}
		} else { // Begin Tag
			$tag = strtolower($regex[1]);

			// Tag Cleaning

			// If it's an empty tag "< >", do nothing
			if ( '' == $tag ) {
				// do nothing
			}
			// ElseIf it presents itself as a self-closing tag...
			elseif ( substr( $regex[2], -1 ) == '/' ) {
				// ...but it isn't a known single-entity self-closing tag, then don't let it be treated as such and
				// immediately close it with a closing tag (the tag will encapsulate no text as a result)
				if ( ! in_array( $tag, $single_tags ) )
					$regex[2] = trim( substr( $regex[2], 0, -1 ) ) . "></$tag";
			}
			// ElseIf it's a known single-entity tag but it doesn't close itself, do so
			elseif ( in_array($tag, $single_tags) ) {
				$regex[2] .= '/';
			}
			// Else it's not a single-entity tag
			else {
				// If the top of the stack is the same as the tag we want to push, close previous tag
				if ( $stacksize > 0 && !in_array($tag, $nestable_tags) && $tagstack[$stacksize - 1] == $tag ) {
					$tagqueue = '</' . array_pop( $tagstack ) . '>';
					$stacksize--;
				}
				$stacksize = array_push( $tagstack, $tag );
			}

			// Attributes
			$attributes = $regex[2];
			if( ! empty( $attributes ) && $attributes[0] != '>' )
				$attributes = ' ' . $attributes;

			$tag = '<' . $tag . $attributes . '>';
			//If already queuing a close tag, then put this tag on, too
			if ( !empty($tagqueue) ) {
				$tagqueue .= $tag;
				$tag = '';
			}
		}
		$newtext .= substr($text, 0, $i) . $tag;
		$text = substr($text, $i + $l);
	}

	// Clear Tag Queue
	$newtext .= $tagqueue;

	// Add Remaining text
	$newtext .= $text;

	// Empty Stack
	while( $x = array_pop($tagstack) )
		$newtext .= '</' . $x . '>'; // Add remaining tags to close

	// WP fix for the bug with HTML comments
	$newtext = str_replace("< !--","<!--",$newtext);
	$newtext = str_replace("<    !--","< !--",$newtext);

	return $newtext;
}

/**
 * Acts on text which is about to be edited.
 *
 * The $content is run through esc_textarea(), which uses htmlspecialchars()
 * to convert special characters to HTML entities. If $richedit is set to true,
 * it is simply a holder for the 'format_to_edit' filter.
 *
 * @since 0.71
 *
 * @param string $content The text about to be edited.
 * @param bool $richedit Whether the $content should not pass through htmlspecialchars(). Default false (meaning it will be passed).
 * @return string The text after the filter (and possibly htmlspecialchars()) has been run.
 */
function format_to_edit( $content, $richedit = false ) {
	$content = apply_filters( 'format_to_edit', $content );
	if (…