private void readNumber()

in johnzon-core/src/main/java/org/apache/johnzon/core/JsonStreamParserImpl.java [760:865]
65 lines of code
38 McCabe index (conditional complexity)

    private void readNumber() {

        char c = buffer[bufferPos];

        //start can change on any read() if we cross buffer boundary
        startOfValueInBuffer = bufferPos;
        endOfValueInBuffer = -1;

        char y = EOF;

        //sum up the digit values 
        int cumulatedDigitValue = 0;
        while (isAsciiDigit(y = readNextChar())) {

            if (c == ZERO) {
                throw uexc("Leading zeros not allowed");
            }

            if (c == MINUS && cumulatedDigitValue == 48) {
                throw uexc("Leading zeros after minus not allowed");
            }

            cumulatedDigitValue += y;

        }

        if (c == MINUS && cumulatedDigitValue == 0) {

            throw uexc("Unexpected premature end of number");
        }

        if (y == DOT) {
            isCurrentNumberIntegral = false;
            cumulatedDigitValue = 0;
            while (isAsciiDigit(y = readNextChar())) {
                cumulatedDigitValue++;
            }

            if (cumulatedDigitValue == 0) {

                throw uexc("Unexpected premature end of number");
            }

        }

        if (y == EXP_LOWERCASE || y == EXP_UPPERCASE) {
            isCurrentNumberIntegral = false;

            y = readNextChar(); //+ or - or digit

            if (!isAsciiDigit(y) && y != MINUS && y != PLUS) {
                throw uexc("Expected DIGIT or + or -");
            }

            if (y == MINUS || y == PLUS) {
                y = readNextChar();
                if (!isAsciiDigit(y)) {
                    throw uexc("Unexpected premature end of number");
                }

            }

            while (isAsciiDigit(y = readNextChar())) {
                //no-op
            }

        }

        endOfValueInBuffer = y == EOF && endOfValueInBuffer < 0 ? -1 : bufferPos;

        if (y == COMMA_CHAR || y == END_ARRAY_CHAR || y == END_OBJECT_CHAR || y == EOL || y == SPACE || y == TAB || y == CR || y == EOF) {

            unreadChar();//unread one char

            //['-', DIGIT]
            if (isCurrentNumberIntegral && c == MINUS && cumulatedDigitValue >= 48 && cumulatedDigitValue <= 57) {

                currentIntegralNumber = -(cumulatedDigitValue - 48); //optimize -0 till -9
                return;
            }

            //[DIGIT]
            if (isCurrentNumberIntegral && c != MINUS && cumulatedDigitValue == 0) {

                currentIntegralNumber = (c - 48); //optimize 0 till 9
                return;
            }

            if (fallBackCopyBufferLength > 0) {

                //we crossed a buffer boundary, use value buffer
                copyCurrentValue();

            } else {
                if ((endOfValueInBuffer - startOfValueInBuffer) >= maxValueLength) {
                    throw tmc();
                }
            }

            return;

        }

        throw uexc("Unexpected premature end of number");

    }