WP_HTML_Decoder::code_point_to_utf8_bytes │ public static │ WP 6.6.0

Encode a code point number into the UTF-8 encoding.

This encoder implements the UTF-8 encoding algorithm for converting a code point into a byte sequence. If it receives an invalid code point it will return the Unicode Replacement Character U+FFFD �.

Example:

'🅰' === WP_HTML_Decoder::code_point_to_utf8_bytes( 0x1f170 );

// Half of a surrogate pair is an invalid code point.
'�' === WP_HTML_Decoder::code_point_to_utf8_bytes( 0xd83c );

Method of the class: WP_HTML_Decoder{}

No Hooks.

Returns

String. Converted code point, or � if invalid.

Usage

$result = WP_HTML_Decoder::code_point_to_utf8_bytes( $code_point ): string;

$code_point(int) (required)

Which code point to convert.

Notes

• See: https://www.rfc-editor.org/rfc/rfc3629 For the UTF-8 standard.

Changelog

WP_HTML_Decoder::code_point_to_utf8_bytes() WP HTML Decoder::code point to utf8 bytes code ^{WP 6.9.1}

public static function code_point_to_utf8_bytes( $code_point ): string {
	// Pre-check to ensure a valid code point.
	if (
		$code_point <= 0 ||
		( $code_point >= 0xD800 && $code_point <= 0xDFFF ) ||
		$code_point > 0x10FFFF
	) {
		return '�';
	}

	if ( $code_point <= 0x7F ) {
		return chr( $code_point );
	}

	if ( $code_point <= 0x7FF ) {
		$byte1 = chr( ( $code_point >> 6 ) | 0xC0 );
		$byte2 = chr( $code_point & 0x3F | 0x80 );

		return "{$byte1}{$byte2}";
	}

	if ( $code_point <= 0xFFFF ) {
		$byte1 = chr( ( $code_point >> 12 ) | 0xE0 );
		$byte2 = chr( ( $code_point >> 6 ) & 0x3F | 0x80 );
		$byte3 = chr( $code_point & 0x3F | 0x80 );

		return "{$byte1}{$byte2}{$byte3}";
	}

	// Any values above U+10FFFF are eliminated above in the pre-check.
	$byte1 = chr( ( $code_point >> 18 ) | 0xF0 );
	$byte2 = chr( ( $code_point >> 12 ) & 0x3F | 0x80 );
	$byte3 = chr( ( $code_point >> 6 ) & 0x3F | 0x80 );
	$byte4 = chr( $code_point & 0x3F | 0x80 );

	return "{$byte1}{$byte2}{$byte3}{$byte4}";
}