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    preg_replace_callback_array

    (PHP 7, PHP 8)

    preg_replace_callback_array — 正規表現検索を行い、コールバック関数を使用して置換を行う

    説明

    preg_replace_callback_array(
        array $pattern,
        string|array $subject,
        int $limit = -1,
        int &$count = null,
        int $flags = 0
    ): string|array|null

    この関数の動作は、preg_replace_callback() に似ていますが、 コールバック関数が、パターン単位ペースで実行されるところが異なります。

    パラメータ

    pattern

    パターンをキーとし、callable を値とする連想配列です。

    subject

    文字列あるいは文字列の配列で、 検索および置換の対象となる文字列を指定します。

    limit

    subject 文字列における 各パターンの最大置換回数。デフォルトは -1 (無制限) です。

    count

    指定した場合は、置換を行った回数がここに格納されます。

    flags

    flags には、 PREG_OFFSET_CAPTURE と PREG_UNMATCHED_AS_NULL の組み合わせが指定できます。 これは matches 配列のフォーマットに影響します。 詳細は preg_match() 関数の説明を参照ください。

    戻り値

    preg_replace_callback_array() は、 subject が配列の場合には配列を、 それ以外の場合は文字列を返します。 エラー時の戻り値は null となります。

    マッチするものが見つかった場合は新しい subject を返し、それ以外の場合はもとの subject をそのまま返します。

    エラー / 例外

    渡された正規表現のパターンがコンパイルできない場合、E_WARNING が発生します。

    変更履歴

    バージョン 説明
    7.4.0 パラメータ flags が追加されました。

    例

    例1 preg_replace_callback_array() の例

    <?php
    $subject     = 'Aaaaaa Bbb';

    preg_replace_callback_array(
    [
    '~[a]+~i' => function ($match) {
    echo     strlen($match[0]), ' matches for "a" found', PHP_EOL;
    },
    '~[b]+~i' => function ($match) {
    echo     strlen($match[0]), ' matches for "b" found', PHP_EOL;
    }
    ],
    $subject
    );
    ?>

    上の例の出力は以下となります。

    6 matches for "a" found
3 matches for "b" found

    参考

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    User Contributed Notes 4 notes

    up
    10
    Sz.
    6 years ago
    Based on some tests, I found these important traits of the function. (These would
    be nice to see documented as part of its spec, e.g. for confirmation. Without that,
    this is just experimental curiosity. Still better than guesswork, though! ;) )

    1. Changes cascade over a subject across callbacks, i.e. a change made to a
    subject by a callback will be seen by the next callback, if its pattern matches
    the changed subject.
    (But a change made by a previous call of the *same* callback (on any subject)
    will not be seen by that callback again.)

    2. The pattern + callback pairs will be applied in the order of their appearance
    in $patterns_and_callbacks.

    3. The callback can't be null (or '') for a quick shortcut for empty replacements.

    4. Overall, the algorithm starts iterating over $patterns_and_callbacks, and then
    feeds each $subject to the current callback, repeatedly for every single match
    of its pattern on the current subject (unlike "preg_match_all", that is, which
    can do the same in one go, returning the accumulated results in an array).

    This basically means that the "crown jewel", an even more efficient function:
    "preg_replace_all_callback_array" is still missing from the collection.

    (Of course, that would better fit a new design of the regex API, where one
    API could flexibly handle various different modes via some $flags = [] array.)

    5. (This last one is not specific to this function, but inherent to regexes, OTOH,
    it's probably more relevant here than anywhere else in PHP's regex support.)

    Even apparently simple cases can generate a crazy (and difficult-to-predict)
    number of matches, and therefore callback invokations, so remember the set
    $limit, where affordable. But, of course, try to sharpen your patterns first!

    E.g. use ^...$ anchoring to avoid unintended extra calls on matching substrings
    of a subject, (I.e. '/.*/', without anchoring, would match twice: once for the
    whole subject, and then for a trailing empty substring -- but I'm not quite sure
    this should actually be correct behavior, though.)
    up
    9
    drevilkuko at gmail dot com
    9 years ago
    finally!!!

    before (<=php5.6):

    <?php
    $htmlString     = preg_replace_callback(
    '/(href="?)(\S+)("?)/i',
    function (&    $matches) {
    return     $matches[1] . urldecode($matches[2]) . $matches[3];
    },
    $htmlString
    );

    $htmlString = preg_replace_callback(
    '/(href="?\S+)(%24)(\S+)?"?/i', // %24 = $
    function (&$matches) {
    return     urldecode($matches[1] . '$' . $matches[3]);
    },
    $htmlString
    );
    ?>

    php7

    <?php

    $htmlString     = preg_replace_callback_array(
    [
    '/(href="?)(\S+)("?)/i' => function (&$matches) {
    return     $matches[1] . urldecode($matches[2]) . $matches[3];
    },
    '/(href="?\S+)(%24)(\S+)?"?/i' => function (&$matches) {
    return     urldecode($matches[1] . '$' . $matches[3]);
    }
    ],
    $htmlString
    );
    ?>
    up
    1
    claus at tondering dot dk
    6 months ago
    Note that the first replacement is applied to the whole string before the next replacement is applied.

    For example:

    <?php
    $subject     = 'a b a b a b';

    preg_replace_callback_array(
    [
    '/a/' => function ($match) {
    echo     '"a" found', PHP_EOL;
    },
    '/b/' => function ($match) {
    echo     '"b" found', PHP_EOL;
    }
    ],
    $subject
    );

    ?>

    will print

    "a" found
    "a" found
    "a" found
    "b" found
    "b" found
    "b" found

    This means that you cannot use global variables to communicate information between the functions about what point in the string you have reached.
    up
    -3
    jfcherng at NOSPAM dot gmail dot com
    8 years ago
    Here's a possible alternative in older PHP.

    <?php

    // if (!function_exists('preg_replace_callback_array')) {

    function preg_replace_callback_array (array $patterns_and_callbacks, $subject, $limit=-1, &$count=NULL) {
    $count = 0;
    foreach (    $patterns_and_callbacks as $pattern => &$callback) {
    $subject = preg_replace_callback($pattern, $callback, $subject, $limit, $partial_count);
    $count += $partial_count;
    }
    return     preg_last_error() == PREG_NO_ERROR ? $subject : NULL;
    }

    // }

    ?>
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