Re^2: Faster regex to split a string into runs of similar characters?

in reply to Re: Faster regex to split a string into runs of similar characters?
in thread Faster regex to split a string into runs of similar characters?

Never would have thought of that! It yeilds another nice chunk of savings in the real application:

C:\test>\perl22\bin\perl 1176081.pl -WIDTH=1000 -HEIGHT=1000
yr() took 2.551594
buk() took 1.068262
buk2() took 0.681494
buk3() took 0.167000
dave() took 0.127978
[download]

Thanks.

On a related note: Any ideas why this:

    while( substr( $$str, $y * $WIDTH, $WIDTH ) =~ m[((.)\2*)]mg ) {
    ...
[download]

Works (runs to completion, produces the desired results) on 5.10.1, but silently loops forever in 5.22.0?

This works in 5.22.0:

        my $ref = \substr( $$str, $y * $WIDTH, $WIDTH );
        while( $$ref  =~ m[((.)\2*)]mg ) {
[download]

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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

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Re^3: Faster regex to split a string into runs of similar characters? by dave_the_m (Monsignor) on Nov 21, 2016 at 14:16 UTC
On a related note: Any ideas why this: `while( substr( $$str, $y * $WIDTH, $WIDTH ) =~ m[((.)\2*)]mg ) { ...` [download] Works (runs to completion, produces the desired results) on 5.10.1, but silently loops forever in 5.22.0? Looks like a bug fix. expr =~ /.../g attaches position magic to the LHS after each match, to record the current pos() for that expression. If expr is a var or similar this works well; if expr returns something new each time, the old pos magic gets lost. This similarly loops forever: `sub f { "abc" } 1 while f() =~ /./g;` [download] Dave.	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^3: Faster regex to split a string into runs of similar characters?
by dave_the_m (Monsignor) on Nov 21, 2016 at 14:16 UTC

On a related note: Any ideas why this:
while( substr( $$str, $y * $WIDTH, $WIDTH ) =~ m[((.)\2*)]mg ) { ...
[download]
Works (runs to completion, produces the desired results) on 5.10.1, but silently loops forever in 5.22.0?

This similarly loops forever:

sub f { "abc" }

1 while f() =~ /./g;
[download]

Dave.

[reply]
[d/l]
[select]

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