字符串中的同一变量随机替换成其他变量

$str = <<<EOF
AAAAAAAAAA{keywords}bbbbbbb
    CCCCCCCCCCCCC
    DDDDDD{keywords}DDDDdddddd
    EEEEEEEEEEEEEEe
    dDDDDDDDDDDDDdd
    EE{keywords}EEEEE
    GGGGGGGGGGGg
   UUUUUUUUUUuuuuuuuuuuuuu
   IIIIIIII{keywords}IIIIIIiii
   
CCCCCCCCCCCCC
    DDDDDD{keywords}DDDDdddddd
    EEEEEEEEEEEEEEe
    dDDDDDDDDDDDDdd
    EE{keywords}EEEEE
    GGGGGGGGGGGg
   UUUUUUUUUUuuuuuuuuuuuuu
   IIIIIIII{keywords}IIIIIIiii

EOF;

$str = preg_replace('/({keywords})/ie', 'regetkeywords("$0")', $str);
echo $str;



function regetkeywords($word) {
    $keywords = '<L>';
$keywords2 = '<0>';
$keywords3 = '<V>';
    static $count = 0;
    $count += mt_rand(1,9);
    if($count%3 == 0) {
        $word = $keywords;
    } elseif ($count%3 == 1) {
        $word = $keywords2;
    } elseif ($count%3 == 2) {
        $word = $keywords3;
    }
    return $word. '('. ($count%3). ')';
}

 php 正则匹配中文

　　php中utf-8编码下用正则表达式匹配汉字的最终正确表达式——/^[x{4e00}-x{9fa5}]+$/u

　　http://blog.sina.com.cn/s/blog_69e1a96d0100vebg.html