public final void readNumber()

in core/src/main/java/com/alibaba/fastjson2/JSONReaderUTF8.java [5411:5611]
179 lines of code
63 McCabe index (conditional complexity)

    public final void readNumber(ValueConsumer consumer, boolean quoted) {
        boolean valid = false;
        this.wasNull = false;
        this.boolValue = false;
        this.mag0 = 0;
        this.mag1 = 0;
        this.mag2 = 0;
        this.mag3 = 0;
        this.negative = false;
        this.exponent = 0;
        this.scale = 0;

        final int end = this.end;
        final byte[] bytes = this.bytes;
        char quote = '\0';
        if (ch == '"' || ch == '\'') {
            quote = ch;
            ch = (char) bytes[offset++];
        }
        final int start = offset;

        if (ch == '-') {
            negative = true;
            ch = (char) bytes[offset++];
        }

        boolean intOverflow = false;
        valueType = JSON_TYPE_INT;
        while (ch >= '0' && ch <= '9') {
            valid = true;
            if (!intOverflow) {
                int mag3_10 = mag3 * 10 + (ch - '0');
                if (mag3_10 < mag3) {
                    intOverflow = true;
                } else {
                    mag3 = mag3_10;
                }
            }
            ch = (char) bytes[offset++];
        }

        if (ch == '.') {
            valueType = JSON_TYPE_DEC;
            ch = (char) bytes[offset++];
            while (ch >= '0' && ch <= '9') {
                valid = true;
                if (!intOverflow) {
                    int mag3_10 = mag3 * 10 + (ch - '0');
                    if (mag3_10 < mag3) {
                        intOverflow = true;
                    } else {
                        mag3 = mag3_10;
                    }
                }

                this.scale++;
                ch = (char) bytes[offset++];
            }
        }

        if (intOverflow) {
            int numStart = negative ? start : start - 1;
            bigInt(bytes, numStart, offset - 1);
        }

        if (ch == 'e' || ch == 'E') {
            boolean negativeExp = false;
            int expValue = 0;
            ch = (char) bytes[offset++];

            if (ch == '-') {
                negativeExp = true;
                ch = (char) bytes[offset++];
            } else if (ch == '+') {
                ch = (char) bytes[offset++];
            }

            while (ch >= '0' && ch <= '9') {
                valid = true;
                int byteVal = (ch - '0');
                expValue = expValue * 10 + byteVal;
                if (expValue > MAX_EXP) {
                    throw new JSONException("too large exp value : " + expValue);
                }
                ch = (char) bytes[offset++];
            }

            if (negativeExp) {
                expValue = -expValue;
            }

            this.exponent = (short) expValue;
            valueType = JSON_TYPE_DEC;
        }

        int len = offset - start;

        if (offset == start) {
            if (ch == 'n') {
                if (bytes[offset++] == 'u'
                        && bytes[offset++] == 'l'
                        && bytes[offset++] == 'l'
                ) {
                    valid = true;
                    wasNull = true;
                    valueType = JSON_TYPE_NULL;
                    ch = (char) bytes[offset++];
                }
            } else if (ch == 't') {
                if (bytes[offset++] == 'r'
                        && bytes[offset++] == 'u'
                        && bytes[offset++] == 'e'
                ) {
                    valid = true;
                    boolValue = true;
                    valueType = JSON_TYPE_BOOL;
                    ch = (char) bytes[offset++];
                }
            } else if (ch == 'f' && offset + 3 < end && IOUtils.isALSE(bytes, offset)) {
                valid = true;
                offset += 4;
                boolValue = false;
                valueType = JSON_TYPE_BOOL;
                ch = (char) bytes[offset++];
            } else if (ch == '{' && quote == 0) {
                this.complex = readObject();
                valueType = JSON_TYPE_OBJECT;
                return;
            } else if (ch == '[' && quote == 0) {
                this.complex = readArray();
                valueType = JSON_TYPE_ARRAY;
                return;
            }
        }

        if (quote != 0) {
            if (ch != quote) {
                this.offset -= 1;
                this.ch = quote;
                readString0();
                valueType = JSON_TYPE_STRING;
                return;
            }
            ch = (char) bytes[offset++];
        }

        while (ch <= ' ' && ((1L << ch) & SPACE) != 0) {
            if (offset >= end) {
                ch = EOI;
            } else {
                ch = (char) bytes[offset++];
            }
        }

        if (comma = (ch == ',')) {
            this.ch = (char) bytes[this.offset++];
            // next inline
            if (this.offset >= end) {
                this.ch = EOI;
            } else {
                while (ch <= ' ' && ((1L << ch) & SPACE) != 0) {
                    if (offset >= end) {
                        ch = EOI;
                    } else {
                        ch = (char) bytes[offset++];
                    }
                }
            }
        }

        if (!quoted && (valueType == JSON_TYPE_INT || valueType == JSON_TYPE_DEC)) {
            consumer.accept(bytes, start - 1, len);
            return;
        }

        if (valueType == JSON_TYPE_INT) {
            if (mag0 == 0 && mag1 == 0 && mag2 == 0 && mag3 != Integer.MIN_VALUE) {
                int intValue = negative ? -mag3 : mag3;
                consumer.accept(intValue);
                return;
            }

            if (mag0 == 0 && mag1 == 0) {
                long v3 = mag3 & 0XFFFFFFFFL;
                long v2 = mag2 & 0XFFFFFFFFL;

                if (v2 <= Integer.MAX_VALUE) {
                    long v23 = (v2 << 32) + (v3);
                    long longValue = negative ? -v23 : v23;
                    consumer.accept(longValue);
                    return;
                }
            }
        }

        Number number = getNumber();
        consumer.accept(number);
        if (!valid) {
            throw new JSONException(info("illegal input error"));
        }
    }