如何使用 preg_replace 和正则表达式替换 php 文件中的代码块？

Question

I have a php config file that contains a few arrays use to store settings.

<?php
$array1 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);
$array2 = array(
    "item1",
    "item2",
    "item3",
    "item4",
);
$array3 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);
?>

I am not very good with regex expression (yet).I am having diffulties understanding how it works. I am trying to build a regex expression that would allow me to replace all lines in array2. Using preg_replace($pattern, $replacement, $str) .

$str=file_get_contents('config.php');
$pattern = "/[$array2 = array(](.*)[);]/";
$replacement = '    "itemA",
    "itemB",
    "itemC",
    "itemD",';
$str=preg_replace($pattern, $replacement, $str);
file_put_contents('config.php', $str);

The expected result would be:

<?php
$array1 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);
$array2 = array(
    "itemA",
    "itemB",
    "itemC",
    "itemD",
);
$array3 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);
?>

Answer 1

I guess, maybe some expression similar to

(\h{2,}"[^"\r\n]+")$

might work here to some level:

RegEx Demo

Test

$re = '/(\h{2,}"[^"\r\n]+")$/m';
$str = '$array1 = array(
    "item1\' => "value1",
    "item2\' => "value2",
    "item3\' => "value3",
    "item4\' => "value4",
);
$array2 = array(
    "item1"
    "item2"
    "item3"
    "item4"
);
$array3 = array(
    "item1\' => "value1",
    "item2\' => "value2",
    "item3\' => "value3",
    "item4\' => "value4",
);';
$subst = '$1,';

$result = preg_replace($re, $subst, $str);

echo $result;

Output

$array1 = array(
    "item1' => "value1",
    "item2' => "value2",
    "item3' => "value3",
    "item4' => "value4",
);
$array2 = array(
    "item1",
    "item2",
    "item3",
    "item4",
);
$array3 = array(
    "item1' => "value1",
    "item2' => "value2",
    "item3' => "value3",
    "item4' => "value4",
);

---

If you wish to simplify/update/explore the expression, it's been explained on the top right panel of regex101.com . You can watch the matching steps or modify them in this debugger link , if you'd be interested. The debugger demonstrates that how a RegEx engine might step by step consume some sample input strings and would perform the matching process.

---

Method 2

I guess, an expression similar to,

(?s)(?<=\$array2 = array\()[^)]*

might be OK to look into.

RegEx Demo 2

$re = '/(?s)(?<=\$array2 = array\()[^)]*/';
$str = '$array1 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);
$array2 = array(
    "item1",
    "item2",
    "item3",
    "item4",
);
$array3 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);';
$subst = '\\n\\t"itemA",\\n\\t"itemB",\\n\\t"itemC",\\n\\t"itemD"\\n';

$result = preg_replace($re, $subst, $str);

echo $result;

Output 2

$array1 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);
$array2 = array(\n\t"itemA",\n\t"itemB",\n\t"itemC",\n\t"itemD"\n);
$array3 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);

Answer 2

Firstly thanks @Emma for all the help. Here is the final code that worked for me simplified with the same example.

config.php

<?php
$array1 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);
$array2 = array(
    "item1",
    "item2",
    "item3",
    "item4",
);
$array3 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);
?>

PHP Code to manipulate the file:

<?php
function format_array($newarray){
    return('    "'.$newarray.'",');
}
$pattern = '/(?s)(?<=\$array2 = array\()[^)]*/';
$myarray = array(
    "itemA",
    "itemB",
    "itemC",
    "itemD",
);
$myarray = array_map("format_array",$myarray);
array_unshift($myarray, '');
array_pop($myarray);
array_push($myarray,'');
$str=file_get_contents('config.php');
$str=preg_replace($pattern,implode(PHP_EOL, $myarray),$str);
file_put_contents('config.php', $str);
?>

Output

<?php
$array1 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);
$array2 = array(
    "itemA",
    "itemB",
    "itemC",
    "itemD",
);
$array3 = array(
    "item1" => "value1",
    "item2" => "value2",
    "item3" => "value3",
    "item4" => "value4",
);
?>

In order to get the expected result including the indents, I had to store the new array and create a leading empty element along with another one at the end. This makes sure that newlines are created in the file so we keep the same formatting.