Re^5: Unsigned 64-bit integer as Judy key

Of course not.

$ perl -MDevel::Peek -E 'Dump $_ for 1<<63,-(1<<63)'
SV = IV(0x559e408d8210) at 0x559e408d8220
  REFCNT = 1
  FLAGS = (IOK,pIOK,IsUV)
  UV = 9223372036854775808
SV = IV(0x559e408d83c0) at 0x559e408d83d0
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = -9223372036854775808

$ perl -MJudy::L=Set -E 'say Set($j, $_, 1) for 1<<63,-(1<<63),0'
94434583711008
Coercing -9223372036854775808 to 0. Can't use negative values as keys.
+ at -e line 1.
94434579767256
94434579767256
[download]

Comment on Re^5: Unsigned 64-bit integer as Judy key Download Code

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Re^6: Unsigned 64-bit integer as Judy key by ikegami (Patriarch) on Dec 09, 2022 at 17:58 UTC
You didn't retrieve any information from the data structure, so you didn't test it at all. Try this: `perl -Mv5.14 -MJudy::L=Get,Set -e' my $i = 1<<63; my $j = -$i; my $judy; Set( $judy, $i, 4 ); Set( $judy, $j, 5 ); say( ( Get( $judy, $i ) )[1] ); say( ( Get( $judy, $j ) )[1] ); '` [download] If you get different values, I was wrong. If you get the same value, each negative value is considered to the same as a very large positive value. Without the hack, it outputs `5` twice. I suspect the hack only silences the warning. Of course not. No, it isn't obvious that the keys are 65 bits (or larger) in size. In fact, they pretty obviously aren't.	[reply] [d/l] [select]

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Re^6: Unsigned 64-bit integer as Judy key
by ikegami (Patriarch) on Dec 09, 2022 at 17:58 UTC

You didn't retrieve any information from the data structure, so you didn't test it at all. Try this:

perl -Mv5.14  -MJudy::L=Get,Set -e'
   my $i = 1<<63;
   my $j = -$i;

   my $judy;

   Set( $judy, $i, 4 );
   Set( $judy, $j, 5 );

   say( ( Get( $judy, $i ) )[1] );
   say( ( Get( $judy, $j ) )[1] );
'
[download]

If you get different values, I was wrong. If you get the same value, each negative value is considered to the same as a very large positive value.

Without the hack, it outputs 5 twice. I suspect the hack only silences the warning.

Of course not.

No, it isn't obvious that the keys are 65 bits (or larger) in size. In fact, they pretty obviously aren't.

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