Re: Why does the lexer convert text integer lexemes to binary integers? I thought that lexers should be simple?

On Fri, 15 Jul 2022 03:02:07 -0700 (PDT), Jan Ziak
<0xe2.0x9a.0x9b@gmail.com> wrote:


>On Friday, July 15, 2022 at 4:13:42 AM UTC+2, George Neuner wrote:
>> In many (actually most) cases, the binary representation of an integer
>> can be stored in less space than the text representation.
>
>The output of a command such as (cd /usr/src/linux; grep --only-matching
>--recursive "\b[0-9][0-9]*\b") proves the falsity of the above claim.
>
>Binary, fixed-width, representation of integers is statistically more
>space-efficient compared to implicit-width textual representation only if the
>text representation of the integers includes (for example): a plain 32/64-bit
>pointer to the start of the text, a plain 16/32/64-bit relative/absolute
>offset to the start of the number in a character array, the [length of the
>textual form of the number] in an explicit form.


???


Decimal 100 is 3 characters in text, but 1 byte in binary.
65535 is 5 characters, but 2 bytes.
2147483648 is 11 characters, but 4 bytes.


0x101010 is 8 characters, 1 byte.
052 is 2 characters, 1 byte.


This dichotomy holds for almost all numbers: regardless of what number
base is used for the text form, the binary form will be shorter.




>Binary, fixed-width, representation of integers is more likely to be more
>space-efficient than [their textual representation with an implicit length] if
>the source of the integers doesn't originate from a human hand typing digits
>on a keyboard. For example, when the source of the integers is a
>high-precision measurement device, is something with a physical counterpart
>(such as: the GPS coordinates of objects spread across Earth's surface), etc.


The source of the value is not relevant - only the form.


>-atom


You completely misunderstood/misinterpreted what I wrote.


I said the binary form CAN BE stored in less space than the text ... I
said NOTHING about being restricted to fixed sized binary integers. It
should be obvious to anyone that storing 42 into a 64-bit integer is
not saving space.


YMMV,
George
[I think the point was that variable length strings are more common than
variable length binary integers, but as a message earlier today pointed out,
it's not likely to make any difference in practical compilers. -John]

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