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#!/usr/bin/perl
use v5.14;
use warnings;
use Test2::V0;
# This "test" never fails, but prints a benchmark comparison between this
# syntax and a simple if/elsif chain
use Time::HiRes qw( gettimeofday tv_interval );
sub measure(&)
{
my ( $code ) = @_;
my $start = [ gettimeofday ];
$code->();
return tv_interval $start;
}
use Syntax::Keyword::Match 0.03 qw( match :experimental(dispatch) );
sub digit_ifelsif
{
my ( $x ) = @_;
if ( $x eq "one" ) { return 1; }
elsif( $x eq "two" ) { return 2; }
elsif( $x eq "three" ) { return 3; }
elsif( $x eq "four" ) { return 4; }
elsif( $x eq "five" ) { return 5; }
elsif( $x eq "six" ) { return 6; }
elsif( $x eq "seven" ) { return 7; }
elsif( $x eq "eight" ) { return 8; }
elsif( $x eq "nine" ) { return 9; }
else { return 0; }
}
sub digit_matchcase
{
my ( $x ) = @_;
match( $x : eq ) {
case( "one" ) { return 1; }
case( "two" ) { return 2; }
case( "three" ) { return 3; }
case( "four" ) { return 4; }
case( "five" ) { return 5; }
case( "six" ) { return 6; }
case( "seven" ) { return 7; }
case( "eight" ) { return 8; }
case( "nine" ) { return 9; }
default { return 0; }
}
}
my $COUNT = 5_000;
my $matchcase_elapsed = 0;
my $ifelsif_elapsed = 0;
# To reduce the influence of bursts of timing noise, interleave many small runs
# of each type.
foreach ( 1 .. 20 ) {
$matchcase_elapsed += measure {
foreach ( 1 .. $COUNT ) {
digit_matchcase $_ for 0 .. 9;
}
};
$ifelsif_elapsed += measure {
foreach ( 1 .. $COUNT ) {
digit_ifelsif $_ for 0 .. 9;
}
};
}
pass( "Benchmarked" );
if( $matchcase_elapsed > $ifelsif_elapsed ) {
diag( sprintf "if/elsif took %.3fsec, ** this was SLOWER at %.3fsec **",
$ifelsif_elapsed, $matchcase_elapsed );
}
else {
my $speedup = ( $ifelsif_elapsed - $matchcase_elapsed ) / $ifelsif_elapsed;
diag( sprintf "if/elsif took %.3fsec, this was %d%% faster at %.3fsec",
$ifelsif_elapsed, $speedup * 100, $matchcase_elapsed );
}
done_testing;
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