PHP中有条件preg_replace吗？

Question

I have some code like this, which replaces some shortcodes with a link:

$search = array(
    '#\{r\|([^|]+)\|([^}]+)\}#',
    '#\{t\|([^|]+)\|([^}]+)\}#',
    ...,
);

$replace = array(
    '<a href="/ref/$1">$2</a>',
    '<a href="/type/$1">$2</a>',
    ...,
);

$content = preg_replace( $search, $replace, $content );

I have lots more that are similar so I was wondering, is there some way to reduce this to one simple preg_replace with a conditional?

For example, use the regex #\{([a-z])\|([^|]+)\|([^}]+)\}# and replace the first match with something different (r=ref, t=type) based on its letter? (If it helps, the shortcodes are like {r|url-slug|LinkTitle}.)

Answer 1

This calls for preg_replace_callback (or possibly just the /e eval modifier), which would allow you to put the mapping t = type and r = ref in the replacement logic:

= preg_replace_callback('#\{([rt])\|([^|]+)\|([^}]+)\}#', "cb_123", ...

function cb_123($m) {

    $map = array("t" => "type",  "r" => "ref");
    $what = $map[  $m[1]  ];

    return "<a href=\"/$what/$m[2]\">$m[3]</a>";
}