Update the list of PHP keywords

[ghost]

Here are some suggestions:

• add __halt_compiler, callable, clone, empty, eval, exit, insteadof, isset, list, unset. See https://secure.php.net/manual/en/reserved.keywords.php;
• remove cfunction or add old_function. Both are defined in PHP 4 only. See https://web.archive.org/web/20090122062341/http://php.net/manual/en/reserved.keywords.php.

Presently, empty(), eval(), exit(), isset(), list(), unset() are recognized as functions because of braces. But __halt_compiler(), array(), die(), empty(), eval(), exit(), isset(), list(), unset() are not functions: they are keywords.

Depending on your decision, I can make a PR with the appropriate RegExp. An example:

/\b(?:__halt_compiler|abstract|and|array|as|break|callable|case|catch|cfunction|class|clone|const|continue|declare|default|die|do|echo|else|elseif|empty|enddeclare|endfor|endforeach|endif|endswitch|endwhile|eval|exit|extends|final|finally|for|foreach|function|global|goto|if|implements|include|include_once|instanceof|insteadof|interface|isset|list|namespace|new|null|old_function|or|parent|print|private|protected|public|require|require_once|return|static|switch|throw|trait|try|unset|use|var|while|xor|yield)\b/i

Is it alright to arrange keywords in alphabetical order? Is there a meaning in the current order? Is it connected with optimization?

I also have suggestions regarding null and parent, but it’s better to start a separate topic for that.

[RunDevelopment]

It's a good idea to update the PHP keyword. I think we can copy the keyword list you linked to as is (including empty, eval, and so on).

Regex looks good (sans the PHP 4 keywords). I'm looking forward to the PR.

remove cfunction or add old_function. Both are defined in PHP 4 only.

I think it's ok to remove the keywords of a PHP version for which support has ended a decade ago.

Is it alright to arrange keywords in alphabetical order? Is there a meaning in the current order? Is it connected with optimization?

Alphabetic order is very much appreciated because it makes it easy to spot missing/duplicate keyword (yes, that happens). Apart from that, the order doesn't matter in this case.

[ghost]

Great, I’ll make this PR today.

I’ll keep null and parent (which are not in the list of keywords) in the RegExp until the next my PR.