PHP preg_replace Expertise Sought

I'm creating some custom BBcode for a forum. I'm trying to get the regular expression right, but it has been eluding me for two days. Any expert advice is welcome.

The input (e.g. sample forum post):

[quote=Bob]I like Candace. She is nice.[/quote]

I agree, she is very nice. I like Ashley, too, and especially [Ryan] when he's drinking.

Essentially, I want to encase any names (from a specified list) in [user][/user] BBcode... except, of course, those being quoted, because doing that causes some terrible parsing errors. Below is an example of how I want the output to be.

The desired output:

[quote=Bob]I like [user]Candace[/user]. She is nice.[/quote]

I agree, she is very nice. I like [user]Ashley[/user], too, and especially [[user]Ryan[/user]] when he's drinking.

My current code:

$searchArray = array(
  '/开发者_如何学JAVA(?i)(Ashley|Bob|Candace|Ryan|Tim)/'
);

$replaceArray = array(
  "[user]\\0[/user]"
);

$text = preg_replace($searchArray, $replaceArray, $input);

$input is of course set to the post contents (i.e. the first example listed above). How can I achieve the results I want? I don't want the regex to match when a name is preceded by an equals sign (=), but putting a [^=] in front of the names in the regex will make it match any non-equals sign character (i.e. spaces), which then messes up the formatting.

Update

The problem is that by using \1 instead of \0 it is omitting the first character before the names (because anything but = is matched). The output results in this:

[quote=Bob]I like[user]Candace[/user]. She is nice.[/quote]

I agree, she is very nice. I like[user]Ashley[/user], too, and especially [user]Ryan[/user]] when he's drinking.

You were on the right track with the [^=] idea. You can put it outside the capture group, and instead of \\0 which is the full match, use \\1 and \\2 i.e. the first & second capture groups

$searchArray = array(
  '/(?i)([^=])(Ashley|Bob|Candace|Ryan|Tim)/'
);

$replaceArray = array(
  "\\1[user]\\2[/user]"
);

$text = preg_replace($searchArray, $replaceArray, $input);