gistfile1.php

<?php

class Encoder
{

	const ENCODE_STYLE_HTML = 0 ;
	const ENCODE_STYLE_JAVASCRIPT = 1 ;
	const ENCODE_STYLE_CSS = 2 ;
	const ENCODE_STYLE_URL = 3 ;
	const ENCODE_STYLE_URL_SPECIAL = 4 ;

	private static $URL_UNRESERVED_CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcedfghijklmnopqrstuvwxyz-_.~' ;

	public function encodeForHTML ( $value )
	{
		$value = str_replace ( '&' , '&amp;' , $value ) ;
		$value = str_replace ( '<' , '&lt;' , $value ) ;
		$value = str_replace ( '>' , '&gt;' , $value ) ;
		$value = str_replace ( '"' , '&quot;' , $value ) ;
		$value = str_replace ( '\'' , '&#x27;' , $value ) ; // &apos; is not recommended
		$value = str_replace ( '/' , '&#x2F;' , $value ) ; // forward slash can help end HTML entity
		return $value ;
	}

	public function encodeForHTMLAttribute ( $value )
	{
		return $this -> _encodeString ( $value ) ;
	}

	public function encodeForJavascript ( $value )
	{
		return $this -> _encodeString ( $value , self::ENCODE_STYLE_JAVASCRIPT ) ;
	}

	public function encodeForURL ( $value )
	{
		return $this -> _encodeString ( $value , self::ENCODE_STYLE_URL_SPECIAL ) ;
	}

	public function encodeForCSS ( $value )
	{
		return $this -> _encodeString ( $value , self::ENCODE_STYLE_CSS ) ;
	}

	/**
	 * Encodes any special characters in the path portion of the URL. Does not
	 * modify the forward slash used to denote directories. If your directory
	 * names contain slashes (rare), use the plain urlencode on each directory
	 * component and then join them together with a forward slash.
	 *
	 * Based on http://en.wikipedia.org/wiki/Percent-encoding and
	 * http://tools.ietf.org/html/rfc3986
	 */
	public function encodeURLPath ( $value )
	{
		$length = mb_strlen ( $value ) ;
		if ( $length == 0 )
		{
			return $value ;
		}
		$output = '' ;
		for ( $i = 0 ; $i < $length ; $i ++ )
		{
			$char = mb_substr ( $value , $i , 1 ) ;
			if ( $char == '/' )
			{
// Slashes are allowed in paths.
				$output .= $char ;
			}
			else if ( mb_strpos ( self::$URL_UNRESERVED_CHARS , $char ) == false )
			{
// It's not in the unreserved list so it needs to be encoded.
				$output .= $this -> _encodeCharacter ( $char , self::ENCODE_STYLE_URL ) ;
			}
			else
			{
// It's in the unreserved list so let it through.
				$output .= $char ;
			}
		}
		return $output ;
	}

	private function _encodeString ( $value , $style = self::ENCODE_STYLE_HTML )
	{
		if ( mb_strlen ( $value ) == 0 )
		{
			return $value ;
		}
		//returns an array of chars in the string, explode and str_split where not used so utf-8 is supported
		// , preg_split splits the string by matching delimiters
		// /u means unicode charcters
		// (?<!subpattern) negative look behind
		// (?!subpattern) negative look ahead
		// ^ is the first character and $ is the last
		$characters = preg_split ( '/(?<!^)(?!$)/u' , $value ) ;
		$output = '' ;
		foreach ( $characters as $c )
		{
			$output .= $this -> _encodeCharacter ( $c , $style ) ;
		}
		return $output ;
	}

	private function _encodeCharacter ( $c , $style = self::ENCODE_STYLE_HTML )
	{
		if ( ctype_alnum ( $c ) )
		{
			return $c ;
		}
		if ( ($style === self::ENCODE_STYLE_URL_SPECIAL) && ($c == '/' || $c == ':') )
		{
			return $c ;
		}
		$charCode = $this -> _unicodeOrdinal ( $c ) ;
		$prefixes = array(
		    self::ENCODE_STYLE_HTML => array( '&#x' , '&#x' ) ,
		    self::ENCODE_STYLE_JAVASCRIPT => array( '\\x' , '\\u' ) ,
		    self::ENCODE_STYLE_CSS => array( '\\' , '\\' ) ,
		    self::ENCODE_STYLE_URL => array( '%' , '%' ) ,
		    self::ENCODE_STYLE_URL_SPECIAL => array( '%' , '%' ) ,
			) ;
		$suffixes = array(
		    self::ENCODE_STYLE_HTML => ';' ,
		    self::ENCODE_STYLE_JAVASCRIPT => '' ,
		    self::ENCODE_STYLE_CSS => '' ,
		    self::ENCODE_STYLE_URL => '' ,
		    self::ENCODE_STYLE_URL_SPECIAL => '' ,
			) ;
// if ASCII, encode with \\xHH
		if ( $charCode < 256 )
		{
			$prefix = $prefixes[ $style ][ 0 ] ;
			$suffix = $suffixes[ $style ] ;
			return $prefix . str_pad ( strtoupper ( dechex ( $charCode ) ) , 2 , '0' ) . $suffix ;
		}
// otherwise encode with \\uHHHH
		$prefix = $prefixes[ $style ][ 1 ] ;
		$suffix = $suffixes[ $style ] ;
		return $prefix . str_pad ( strtoupper ( dechex ( $charCode ) ) , 4 , '0' ) . $suffix ;
	}

	private function _unicodeOrdinal ( $u )
	{
		/*
		 * Convert character encoding
		 * Converts the character encoding of string str to to_encoding from optionally from_encoding. 
		 * string mb_convert_encoding ( string $str 
		 * , string $to_encoding 
		 * [, mixed $from_encoding = mb_internal_encoding() ] )
		 */
		$c = mb_convert_encoding ( $u , 'UCS-2LE' , 'UTF-8' ) ;
		$c1 = ord ( substr ( $c , 0 , 1 ) ) ;
		$c2 = ord ( substr ( $c , 1 , 1 ) ) ;
		return $c2 * 256 + $c1 ;
	}

}