替换字符串中的占位符变量

Question

刚刚完成这个功能.基本上,假设查看字符串并尝试查找任何占位符变量,这些变量将位于两个大括号之间{}.它抓取大括号之间的值,并使用它来查看应与键匹配的数组.然后它用匹配键数组中的值替换字符串中的大括号变量.

但它有一些问题.首先是当var_dump($matches)它把它放在数组中的数组时.所以我必须使用两个foreach()只是达到正确的数据.

我也觉得它很沉重,我一直在寻找它,试图让它变得更好,但我有点难过.我错过了任何优化？

function dynStr($str,$vars) {
    preg_match_all("/\{[A-Z0-9_]+\}+/", $str, $matches);
    foreach($matches as $match_group) {
        foreach($match_group as $match) {
            $match = str_replace("}", "", $match);
            $match = str_replace("{", "", $match);
            $match = strtolower($match);
            $allowed = array_keys($vars);
            $match_up = strtoupper($match);
            $str = (in_array($match, $allowed)) ? str_replace("{".$match_up."}", $vars[$match], $str) : str_replace("{".$match_up."}", '', $str);
        }
    }
    return $str;
}

$variables = array("first_name"=>"John","last_name"=>"Smith","status"=>"won");
$string = 'Dear {FIRST_NAME} {LAST_NAME}, we wanted to tell you that you {STATUS} the competition.';
echo dynStr($string,$variables);
//Would output: 'Dear John Smith, we wanted to tell you that you won the competition.'

Answer 1

我认为对于这么简单的任务,您不需要使用RegEx:

$variables = array("first_name"=>"John","last_name"=>"Smith","status"=>"won");
$string = 'Dear {FIRST_NAME} {LAST_NAME}, we wanted to tell you that you {STATUS} the competition.';

foreach($variables as $key => $value){
    $string = str_replace('{'.strtoupper($key).'}', $value, $string);
}

echo $string; // Dear John Smith, we wanted to tell you that you won the competition.

Answer 2

我希望我加入聚会还不算太晚 - 这就是我要做的事情:

function template_substitution($template, $data) {
    $placeholders = array_keys($data);
    foreach ($placeholders as &$placeholder) {
        $placeholder = strtoupper("{{$placeholder}}");
    }
    return str_replace($placeholders, array_values($data), $template);
}

$variables = array(
    'first_name' => 'John',
    'last_name' => 'Smith',
    'status' => 'won',
);

$string = 'Dear {FIRST_NAME} {LAST_NAME}, we wanted to tell you that you have {STATUS} the competition.';

echo template_substitution($string, $variables);

并且,如果您有可能使您的$variables密钥与您的占位符完全匹配,那么解决方案变得非常简单:

$variables = array(
    '{FIRST_NAME}' => 'John',
    '{LAST_NAME}' => 'Smith',
    '{STATUS}' => 'won',
);

$string = 'Dear {FIRST_NAME} {LAST_NAME}, we wanted to tell you that you have {STATUS} the competition.';

echo strtr($string, $variables);

(参见PHP手册中的strtr().)

考虑到PHP语言的本质,我相信这种方法应该能够从这个线程中列出的所有内容中获得最佳性能.

Answer 3

我认为你可以大大简化你的代码(除非我误解了一些要求):

$allowed = array("first_name"=>"John","last_name"=>"Smith","status"=>"won");

$resultString = preg_replace_callback(

    // the pattern, no need to escape curly brackets
    // uses a group (the parentheses) that will be captured in $matches[ 1 ]
    '/{([A-Z0-9_]+)}/',

    // the callback, uses $allowed array of possible variables
    function( $matches ) use ( $allowed )
    {
        $key = strtolower( $matches[ 1 ] );
        // return the complete match (captures in $matches[ 0 ]) if no allowed value is found
        return array_key_exists( $key, $allowed ) ? $allowed[ $key ] : $matches[ 0 ];
    },

    // the input string
    $yourString
);

PS.:如果要删除输入字符串中不允许的占位符,请替换

return array_key_exists( $key, $allowed ) ? $allowed[ $key ] : $matches[ 0 ];

同

return array_key_exists( $key, $allowed ) ? $allowed[ $key ] : '';