Disaster Continues

/^(\w+|::)*$/

• Try

     perl -Mre=debug -e '"abcd!" =~ /^(?:\w+|::)*$/'

• It generates 279 lines of diagnostic output about the backtracking that it tried before it gave up.

     perl -Mre=debug -e '"abcde!" =~ /^(?:\w+|::)*$/'

takes twice as long and generates twice as much: 535 lines. We would expect

     perl -Mre=debug -e '"what_an_incredible_disaster!" =~ /^(?:\w+|::)*$/'

to take about 8,388,608 times as long and to generate 2,147,483,671 lines of output.

• It doesn't take forever, but it's hard to tell the difference.

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Copyright © 2002 M. J. Dominus