static JsonNumber parseNumber()

in src/main/user-impl/java/com/mysql/cj/xdevapi/JsonParser.java [438:529]
82 lines of code
29 McCabe index (conditional complexity)

    static JsonNumber parseNumber(StringReader reader) throws IOException {
        StringBuilder sb = null;
        char lastChar = ' ';
        boolean hasFractionalPart = false;
        boolean hasExponent = false;

        int intch;
        while ((intch = reader.read()) != -1) {
            char ch = (char) intch;

            if (sb == null) {
                // number is still not found
                if (ch == '\u002D') {
                    // first char of number is minus
                    sb = new StringBuilder();
                    sb.append(ch);
                } else if (ch >= '\u0030' && ch <= '\u0039') {
                    // first char of number is digit
                    sb = new StringBuilder();
                    sb.append(ch);
                } else if (!whitespaceChars.contains(ch)) {
                    // only white spaces are allowed before value
                    throw ExceptionFactory.createException(WrongArgumentException.class, Messages.getString("JsonParser.1", new Character[] { ch }));
                }
            } else if (ch == '\u002D') {
                // '-' is allowed only on first position and after exponent character
                if (lastChar == 'E' || lastChar == 'e') {
                    sb.append(ch);
                } else {
                    throw ExceptionFactory.createException(WrongArgumentException.class,
                            Messages.getString("JsonParser.8", new Object[] { ch, sb.toString() }));
                }

            } else if (ch >= '\u0030' && ch <= '\u0039') { // 0-9
                sb.append(ch);

            } else if (ch == 'E' || ch == 'e') {
                // exponent character is allowed only after a digit
                if (lastChar >= '\u0030' && lastChar <= '\u0039') {
                    hasExponent = true;
                    sb.append(ch);
                } else {
                    throw ExceptionFactory.createException(WrongArgumentException.class,
                            Messages.getString("JsonParser.8", new Object[] { ch, sb.toString() }));
                }

            } else if (ch == '\u002E') {
                // '.' is allowed only once, after a digit and not in exponent part
                if (hasFractionalPart) {
                    throw ExceptionFactory.createException(WrongArgumentException.class,
                            Messages.getString("JsonParser.10", new Object[] { ch, sb.toString() }));
                }
                if (hasExponent) {
                    throw ExceptionFactory.createException(WrongArgumentException.class, Messages.getString("JsonParser.11"));
                }
                if (lastChar >= '\u0030' && lastChar <= '\u0039') {
                    hasFractionalPart = true;
                    sb.append(ch);
                } else {
                    throw ExceptionFactory.createException(WrongArgumentException.class,
                            Messages.getString("JsonParser.8", new Object[] { ch, sb.toString() }));
                }

            } else if (ch == '\u002B') {
                // '+' is allowed only once after exponent character
                if (lastChar == 'E' || lastChar == 'e') {
                    sb.append(ch);
                } else {
                    throw ExceptionFactory.createException(WrongArgumentException.class,
                            Messages.getString("JsonParser.8", new Object[] { ch, sb.toString() }));
                }

            } else if (whitespaceChars.contains(ch) || isValidEndOfValue(ch)) {
                // any whitespace, comma or right bracket character means the end of Number in case we already placed something to buffer
                reader.reset(); // set reader position to last number char
                break;

            } else {
                // no other characters are allowed after value
                throw ExceptionFactory.createException(WrongArgumentException.class, Messages.getString("JsonParser.1", new Character[] { ch }));
            }
            lastChar = ch;
            // it's safe to mark() here because the "higher" level marks won't be reset() once we start reading a number
            reader.mark(1);
        }

        if (sb == null || sb.length() == 0) {
            throw ExceptionFactory.createException(WrongArgumentException.class, Messages.getString("JsonParser.5"));
        }

        return new JsonNumber().setValue(sb.toString());
    }