function utf8Slice()

in web-ui/src/js/axios.js [1359:1430]
66 lines of code
24 McCabe index (conditional complexity)

	function utf8Slice (buf, start, end) {
	  end = Math.min(buf.length, end)
	  var res = []
	
	  var i = start
	  while (i < end) {
	    var firstByte = buf[i]
	    var codePoint = null
	    var bytesPerSequence = (firstByte > 0xEF) ? 4
	      : (firstByte > 0xDF) ? 3
	      : (firstByte > 0xBF) ? 2
	      : 1
	
	    if (i + bytesPerSequence <= end) {
	      var secondByte, thirdByte, fourthByte, tempCodePoint
	
	      switch (bytesPerSequence) {
	        case 1:
	          if (firstByte < 0x80) {
	            codePoint = firstByte
	          }
	          break
	        case 2:
	          secondByte = buf[i + 1]
	          if ((secondByte & 0xC0) === 0x80) {
	            tempCodePoint = (firstByte & 0x1F) << 0x6 | (secondByte & 0x3F)
	            if (tempCodePoint > 0x7F) {
	              codePoint = tempCodePoint
	            }
	          }
	          break
	        case 3:
	          secondByte = buf[i + 1]
	          thirdByte = buf[i + 2]
	          if ((secondByte & 0xC0) === 0x80 && (thirdByte & 0xC0) === 0x80) {
	            tempCodePoint = (firstByte & 0xF) << 0xC | (secondByte & 0x3F) << 0x6 | (thirdByte & 0x3F)
	            if (tempCodePoint > 0x7FF && (tempCodePoint < 0xD800 || tempCodePoint > 0xDFFF)) {
	              codePoint = tempCodePoint
	            }
	          }
	          break
	        case 4:
	          secondByte = buf[i + 1]
	          thirdByte = buf[i + 2]
	          fourthByte = buf[i + 3]
	          if ((secondByte & 0xC0) === 0x80 && (thirdByte & 0xC0) === 0x80 && (fourthByte & 0xC0) === 0x80) {
	            tempCodePoint = (firstByte & 0xF) << 0x12 | (secondByte & 0x3F) << 0xC | (thirdByte & 0x3F) << 0x6 | (fourthByte & 0x3F)
	            if (tempCodePoint > 0xFFFF && tempCodePoint < 0x110000) {
	              codePoint = tempCodePoint
	            }
	          }
	      }
	    }
	
	    if (codePoint === null) {
	      // we did not generate a valid codePoint so insert a
	      // replacement char (U+FFFD) and advance only 1 byte
	      codePoint = 0xFFFD
	      bytesPerSequence = 1
	    } else if (codePoint > 0xFFFF) {
	      // encode to utf16 (surrogate pair dance)
	      codePoint -= 0x10000
	      res.push(codePoint >>> 10 & 0x3FF | 0xD800)
	      codePoint = 0xDC00 | codePoint & 0x3FF
	    }
	
	    res.push(codePoint)
	    i += bytesPerSequence
	  }
	
	  return decodeCodePointsArray(res)
	}