Single regex that changes camel-case to dash-separated lowercase

Question

I'm trying to write a SublimeText snippet for javascript import statements. I want the format the format to be like:

import MyFooBar from 'my-foo-bar';

The input to my regex is MyFooBar, and the output needs to be my-foo-bar. I found an answer that almost works in Regex - CamelCase to lower case with underscores:

Search for

((?<=.)[A-Z][a-zA-Z]*)|((?<=[a-zA-Z])\d+)

Replace with

-$1$2

The answer said to just use javascript's .toLowerCase() method for the lowercasing, but SublimeText snippets use perl, of which I have the briefest of knowledge. A quick search said that for lowercasing, I can use \L at the beginning of my replacement.

/((?<=.)[A-Z][a-zA-Z0-9]*)|((?<=[a-zA-Z])\d+)/\L-\1\2/g

This works on all but the first segment's character, so MyFooBar becomes My-foo-bar.

I thought maybe I could run two regexes in sequence, but either perl or Sublime doesn't recognize that.

Thoughts?

Edit:

When I say it uses perl, I just mean it uses a perl regex. As far as I can tell, I can't actually execute arbitrary code; I can only specify a regex that perl can execute.

Here's the full text of my snippet:

<snippet>
    <content><![CDATA[
import ${1:module} from '${2:./path/}${1/((?<=.)[A-Z][a-zA-Z0-9]*)|((?<=[a-zA-Z])\d+)/\L-\1\2/g}';
]]></content>
    <!-- Optional: Set a tabTrigger to define how to trigger the snippet -->
    <tabTrigger>import</tabTrigger>
    <!-- Optional: Set a scope to limit where the snippet will trigger -->
    <scope>source.js</scope>
</snippet>

Answer 1

I changed RegEx to something more useful and probably simple.

** Updated

<snippet>
    <content><![CDATA[
import ${1:module} from '${2:./path/}${1/(^[A-Z][a-z]+|[a-z])([A-Z])/\L\1-\2/g}';
]]></content>
    <!-- Optional: Set a tabTrigger to define how to trigger the snippet -->
    <tabTrigger>import</tabTrigger>
    <scope>source.js</scope>
</snippet>

Answer 2

Ugly (substr()) but works:

$x = "MyFooBar";
$x =~ s/(?:^|(?<=[a-z])(?=[A-Z]))(.)/-lc($1)/eg;
$x = substr($x, 1);
print $x;
// my-foo-bar

See a demo on ideone.com.

Answer 3

This one took me a little while, but I believe it does what you want, all within a single regex:

use warnings;
use strict;

while (<DATA>){
    chomp;
    s/([[:upper:]].*?)(?=(?:[[:upper:]]|$))/$+[0]!=length($_) ? lc($1).'-' : lc($1)/ge;
    print "$_\n";
}

__DATA__
MyCamelCase
AVeryLongCamelCaseStringWMXThat

Output:

my-camel-case
a-very-long-camel-case-string-w-m-x-that

Explanation: It looks for an upper case letter, and captures into $1 that letter, along with all other letters until it sees another capital or end of string within a zero-width lookahead. in the substitution side, we use the /e modifier which means the right-hand side is an expression (executable code). If the end of the most recent match ($+[0]) is less than the length of the string, we do a lower (lc()) and append a -. If the length of the string is the same as the end of the last match, we lowercase it and we're done.