CamelCase to LowerDashCase - Without Regex - php

Question

I have the following functions:
function dashesToCamelCase($string)
{
return str_replace(' ', '', ucwords(str_replace('-', ' ', $string)));
}
function camelCaseToDashes($string) {
//This method should not have Regex
$string = preg_replace('/\B([A-Z])/', '-$1', $string);
return strtolower($string);
}
And here is a Test:
$testArray = ['UserProfile', 'UserSettings', 'Settings', 'SuperLongString'];
foreach ($testArray as $testData) {
$dashed = camelCaseToDashes($testData);
$orignal = dashesToCamelCase($dashed);
echo '<pre>' . $dashed . ' | ' . $orignal . '</pre>';
}
This is the expected output:
user-profile | UserProfile
user-settings | UserSettings
settings | Settings
super-long-string | SuperLongString
Now my Question: The method camelCaseToDashes now is using Regex. Can you imagine a better (faster) implementation without Regex?

Answer 1

You should really first check a profiler graph before optimizing the wrong thing.
Visualize the actual execution time your preg_replace takes.
Replacing a regex with various PHP string function workarounds is not usually an optimization.

Answer 2

Try this:
$text = 'CamelCaseString';
$result = '';
for ($i = 0; $i < strlen($text); $i++) {
$result .= $i > 0 && ord($text[$i]) >= 64 && ord($text[$i]) <= 90 ? '-'.$text[$i] : $text[$i];
}
var_dump(strtolower($result));
You can create a benchmark to see performance of each solution.
Actually, according to my benchmark, solution with regular expression seems to be roughly 10× faster:
$ php test2.php
regex: 0.41732287406921
without regex: 3.5226600170135
I guess, that regular expression would be better, because it's implemented in C. My algorithm is implemented in PHP, which has significantly worse performance. With few optimizations I was able to improve time of 100,000 iterations of my algorithm to 2.5 second (compare to 0.4 second of 100,000 iterations of regexp).
Improved version:
$text = 'CamelCaseString';
$result = '';
$lenght = strlen($text);
for ($i = 0; $i < $lenght; $i++) {
$ord = ($text[$i]);
$result .= $i > 0 && $ord >= 64 && $ord <= 90 ? '-'.$text[$i] : $text[$i];
}
$ php test2.php
regex: 0.40657687187195
without regex: 2.5361099243164
Also interesting thing:
As you can see on a profile of your function, function preg_replace takes only 12 % of total time, strtolower takes under 1 %. There is no other code in the function regex. But it's possible that this is overhead of Xdebug. Profile was visualized by qCacheGrind.

Answer 3

If you want a ridiculous gain try this:
function dashesToCamelCase2($string) {
return strtr(ucwords(strtr($string, '-', ' ')), ' ', '');
}
function camelCaseToDashes2($string) {
return strtolower(preg_replace('/(?=[A-Z])\B/', '-', $string));
}