Iri::remove_iunreserved_percent_encoded( array $regex_match ): string

Source

protected function remove_iunreserved_percent_encoded($regex_match) {
	// As we just have valid percent encoded sequences we can just explode
	// and ignore the first member of the returned array (an empty string).
	$bytes = explode('%', $regex_match[0]);

	// Initialize the new string (this is what will be returned) and that
	// there are no bytes remaining in the current sequence (unsurprising
	// at the first byte!).
	$string = '';
	$remaining = 0;

	// Loop over each and every byte, and set $value to its value
	for ($i = 1, $len = count($bytes); $i < $len; $i++) {
		$value = hexdec($bytes[$i]);

		// If we're the first byte of sequence:
		if (!$remaining) {
			// Start position
			$start = $i;

			// By default we are valid
			$valid = true;

			// One byte sequence:
			if ($value <= 0x7F) {
				$character = $value;
				$length = 1;
			}
			// Two byte sequence:
			elseif (($value & 0xE0) === 0xC0) {
				$character = ($value & 0x1F) << 6;
				$length = 2;
				$remaining = 1;
			}
			// Three byte sequence:
			elseif (($value & 0xF0) === 0xE0) {
				$character = ($value & 0x0F) << 12;
				$length = 3;
				$remaining = 2;
			}
			// Four byte sequence:
			elseif (($value & 0xF8) === 0xF0) {
				$character = ($value & 0x07) << 18;
				$length = 4;
				$remaining = 3;
			}
			// Invalid byte:
			else {
				$valid = false;
				$remaining = 0;
			}
		}
		// Continuation byte:
		else {
			// Check that the byte is valid, then add it to the character:
			if (($value & 0xC0) === 0x80) {
				$remaining--;
				$character |= ($value & 0x3F) << ($remaining * 6);
			}
			// If it is invalid, count the sequence as invalid and reprocess the current byte as the start of a sequence:
			else {
				$valid = false;
				$remaining = 0;
				$i--;
			}
		}

		// If we've reached the end of the current byte sequence, append it to Unicode::$data
		if (!$remaining) {
			// Percent encode anything invalid or not in iunreserved
			if (
				// Invalid sequences
				!$valid
				// Non-shortest form sequences are invalid
				|| $length > 1 && $character <= 0x7F
				|| $length > 2 && $character <= 0x7FF
				|| $length > 3 && $character <= 0xFFFF
				// Outside of range of iunreserved codepoints
				|| $character < 0x2D
				|| $character > 0xEFFFD
				// Noncharacters
				|| ($character & 0xFFFE) === 0xFFFE
				|| $character >= 0xFDD0 && $character <= 0xFDEF
				// Everything else not in iunreserved (this is all BMP)
				|| $character === 0x2F
				|| $character > 0x39 && $character < 0x41
				|| $character > 0x5A && $character < 0x61
				|| $character > 0x7A && $character < 0x7E
				|| $character > 0x7E && $character < 0xA0
				|| $character > 0xD7FF && $character < 0xF900
			) {
				for ($j = $start; $j <= $i; $j++) {
					$string .= '%' . strtoupper($bytes[$j]);
				}
			}
			else {
				for ($j = $start; $j <= $i; $j++) {
					$string .= chr(hexdec($bytes[$j]));
				}
			}
		}
	}

	// If we have any bytes left over they are invalid (i.e., we are
	// mid-way through a multi-byte sequence)
	if ($remaining) {
		for ($j = $start; $j < $len; $j++) {
			$string .= '%' . strtoupper($bytes[$j]);
		}
	}

	return $string;
}

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