function decodeSymbol()

in Events and Hacks/Tech Talks/ContainerDemo/example-voting-app/result/views/socket.io.js [5044:5105]

49 lines of code
11 McCabe index (conditional complexity)


	function decodeSymbol() {
		var byte1;
		var byte2;
		var byte3;
		var byte4;
		var codePoint;

		if (byteIndex > byteCount) {
			throw Error('Invalid byte index');
		}

		if (byteIndex == byteCount) {
			return false;
		}

		// Read first byte
		byte1 = byteArray[byteIndex] & 0xFF;
		byteIndex++;

		// 1-byte sequence (no continuation bytes)
		if ((byte1 & 0x80) == 0) {
			return byte1;
		}

		// 2-byte sequence
		if ((byte1 & 0xE0) == 0xC0) {
			var byte2 = readContinuationByte();
			codePoint = ((byte1 & 0x1F) << 6) | byte2;
			if (codePoint >= 0x80) {
				return codePoint;
			} else {
				throw Error('Invalid continuation byte');
			}
		}

		// 3-byte sequence (may include unpaired surrogates)
		if ((byte1 & 0xF0) == 0xE0) {
			byte2 = readContinuationByte();
			byte3 = readContinuationByte();
			codePoint = ((byte1 & 0x0F) << 12) | (byte2 << 6) | byte3;
			if (codePoint >= 0x0800) {
				checkScalarValue(codePoint);
				return codePoint;
			} else {
				throw Error('Invalid continuation byte');
			}
		}

		// 4-byte sequence
		if ((byte1 & 0xF8) == 0xF0) {
			byte2 = readContinuationByte();
			byte3 = readContinuationByte();
			byte4 = readContinuationByte();
			codePoint = ((byte1 & 0x0F) << 0x12) | (byte2 << 0x0C) |
				(byte3 << 0x06) | byte4;
			if (codePoint >= 0x010000 && codePoint <= 0x10FFFF) {
				return codePoint;
			}
		}

		throw Error('Invalid UTF-8 detected');
	}