RFR: 8316150: Refactor get chars and string size [v7]

[温绍锦]

On Fri, 22 Sep 2023 09:22:04 GMT, 温绍锦 <duke at openjdk.org> wrote:

>> 1. Reduce duplicate stringSize code
>> 2. Move java.lang.StringLatin1.getChars to jdk.internal.util.DecimalDigits::getCharLatin1，not only java.lang, other packages also need to use this method
>
> 温绍锦 has updated the pull request incrementally with one additional commit since the last revision:
> 
>   restore HexDigits & OctalDigits

private static final MethodHandle PUT_CHAR_DIGIT;

    static {
        try {
            Lookup lookup = MethodHandles.lookup();
            PUT_CHAR_DIGIT = lookup.findStatic(FormatItem.class, "putByte",
                    MethodType.methodType(void.class,
                            byte[].class, int.class, int.class));
        } catch (ReflectiveOperationException ex) {
            throw new AssertionError("putByte lookup failed", ex);
        }
    }

    private static void putByte(byte[] buffer, int index, int ch) {
        buffer[index] = (byte)ch;
    }

   int length = DecimalDigits.INSTANCE.size(value);
   DecimalDigits.INSTANCE.digits(value, this.digits, length, PUT_CHAR_DIGIT);


In the current implementation, FormatItem only calls DecimalDigits using the encoding of LATIN1

-------------

PR Comment: https://git.openjdk.org/jdk/pull/15699#issuecomment-1731821226