You may be better off doing the initial check without using the regex engine;
only using it with split where necessary.
As you can see from ++aaron_baugher's analysis,
your results will depend on your real data.
Furthermore, if your volume of data is small, your choice of solution may make little difference (in terms of runtime).
Here's a solution using substr, rindex and length for the initial check.
As a proof-of-concept to show that these functions work on characters (as opposed to bytes), I've included single-byte and multi-byte characters in the data.
#!/usr/bin/env perl -l
use strict;
use warnings;
use utf8;
use open OUT => ':utf8', ':std';
my @strings = (
'A B C', 'D E', 'F ', 'G', 'H ', 'I ',
"\N{MERCURY} \N{FEMALE SIGN} \N{EARTH}", "\N{MALE SIGN} \N{JUPITER
+}",
"\N{SATURN} ", "\N{URANUS}", "\N{NEPTUNE} ", "\N{PLUTO} ",
);
for (@strings) {
next if substr($_, -1, 1) eq ' ' or rindex($_, ' ', length() - 2)
+== -1;
print;
}
Output:
A B C
D E
☿ ♀ ♁
♂ ♃
[The Unicode range of characters labelled "Astrological symbols" is 0x263d to 0x2647.
There is no charname for "VENUS" or "MARS";
the charnames "FEMALE SIGN" and "MALE SIGN" are defined for these symbols, respectively.]
Here's a benchmark test. This uses my sample data.
If you choose this route, you should benchmark with representative samples of your data.
#!/usr/bin/env perl -l
use strict;
use warnings;
use Benchmark qw{cmpthese};
my @strings = (
'A B C', 'D E', 'F ', 'G', 'H ', 'I ',
"\N{MERCURY} \N{FEMALE SIGN} \N{EARTH}", "\N{MALE SIGN} \N{JUPITER
+}",
"\N{SATURN} ", "\N{URANUS}", "\N{NEPTUNE} ", "\N{PLUTO} ",
);
my $re = qr{\s+\b};
cmpthese -1 => {
no_re_check_and_split => \&no_re_check_and_split,
re_check_and_split => \&re_check_and_split,
split_and_re_check => \&split_and_re_check,
};
sub no_re_check_and_split {
for (@strings) {
next if substr($_, -1, 1) eq ' ' or rindex($_, ' ', length() -
+ 2) == -1;
my @parts = split /$re/;
}
}
sub re_check_and_split {
for (@strings) {
next unless /$re/;
my @parts = split /$re/;
}
}
sub split_and_re_check {
for (@strings) {
my @parts = split /$re/;
next if @parts > 1;
}
}
Here's three sample runs:
Rate split_and_re_check re_check_and_split no
+_re_check_and_split
split_and_re_check 50243/s -- -18%
+ -29%
re_check_and_split 61265/s 22% --
+ -13%
no_re_check_and_split 70274/s 40% 15%
+ --
Rate split_and_re_check re_check_and_split no
+_re_check_and_split
split_and_re_check 53593/s -- -19%
+ -27%
re_check_and_split 66370/s 24% --
+ -10%
no_re_check_and_split 73770/s 38% 11%
+ --
Rate split_and_re_check re_check_and_split no
+_re_check_and_split
split_and_re_check 53096/s -- -20%
+ -27%
re_check_and_split 66369/s 25% --
+ -8%
no_re_check_and_split 72404/s 36% 9%
+ --
ken@ganymede: ~/tmp
With my sample data, doing the initial check without a regex appears faster.
Again, I'll stress, you'll need to check with your data.
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