从字符串中的数组键替换匹配的字符串

Question

我的目标是，在一个字符串中，找到一个假定数组的键，并在该字符串中，用数组中匹配的键替换这些键。

我有一个小而有用的函数，可以在 2 个分隔符之间找到我的所有字符串（沙盒链接：https://repl.it/repls/UnlinedDodgerblueAbstractions）：

function findBetween( $string, $start, $end )
{
    $start = preg_quote( $start, '/' );
    $end = preg_quote( $end, '/' );

    $format = '/(%s)(.*?)(%s)/';

    $pattern = sprintf( $format, $start, $end );

    preg_match_all( $pattern, $string, $matches );

    $number_of_matches = is_string( $matches[2] ) ? 1 : count( $matches[2] );

    if( $number_of_matches === 1 ) {
        return $matches[2];
    }

    if( $number_of_matches < 2 || empty( $matches ) ) {
        return False;
    }

    return $matches[2];
}

例子：

findBetween( 'This thing should output _$this_key$_ and also _$this_one$_ so that I can match it with an array!', '_$', '$_')

应该返回一个包含值['this_key', 'this_one'] 的数组。问题是，我怎样才能将它们替换为关联数组的值？

假设我的数组是这样的：

[
    'this_key' => 'love',
    'this_one' => 'more love'
];

我的输出应该是这样的：

This thing should output love and also more love so that I can match it with an array!

我怎样才能做到这一点？

Answer 1

使用strtr 可能比使用正则表达式更容易解决这个问题。我们可以使用array_map在$replacements的key周围加上$start和$end的值，然后使用strtr进行替换：

$str = 'This thing should output _$this_key$_ and also _$this_one$_ so that I can match it with an array!';
$replacements = [
    'this_key' => 'love',
    'this_one' => 'more love'
];
$start = '_$';
$end = '$_';
$replacements = array_combine(array_map(function ($v) use ($start, $end) { return "$start$v$end"; }, array_keys($replacements)), $replacements);
echo strtr($str, $replacements);

输出：

This thing should output love and also more love so that I can match it with an array!

Demo on 3v4l.org

如果因为每次都必须重新生成 $replacements 数组而导致性能问题，那么这个循环会快得多：

foreach ($replacements as $key => $value) {
    $new_reps["_\$$key\$_"] = $value;
}

性能对比demo on 3v4l.org

Answer 2

您可以使用preg_replace_callback:

<?php

$str = 'This thing should output _$this_key$_ and also _$this_one$_ so that I can match it with an array!';

$replacements = [
    'this_key' => 'love',
    'this_one' => 'more love'
];

$replaced = preg_replace_callback('/_\$([^$]+)\$_/', function($matches) use ($replacements) {
    return $replacements[$matches[1]];
}, $str);

print $replaced;

你有一个演示 here。

正则表达式，解释：

_              # Literal '_'
\$             # Literal '$' ($ needs to be scaped as it means end of line/string)
(              # Begin of first capturing group
    [^$]+      # One carcter that cannot be "$", repeated 1 or more times
)              # End of first capturing group
\$             # Literal '$'
_              # Literal '_'

对于每个匹配，匹配的数据 ($mathces) 被传递给函数。

在数组的第一个元素上有第一个捕获组，我们用它来进行替换。

Answer 3

希望这能解决您的问题！

$items['this_key'] = 'love';
$items['this_one'] = 'more love';

$string = 'This thing should output _$this_key$_ and also _$this_one$_ so that I can match it with an array!';

$this_key = $items['this_key'];
$this_one = $items['this_one'];
$string = str_replace('_$this_key$_',$this_key,$string);
$string = str_replace('_$this_one$_',$this_one,$string);

echo  $string;