Read and join multiple remote files PHP

I’m using this code to read multiple remote files:

$filters = [ "https://example.com/file.txt", "https://example.com/file1.txt", "https://example.com/file3.txt" ]

function parseFilterLists( $filters )
  {
    foreach( $filters as $filter ){
      $file =  file_get_contents( $filter );
      $parsed = preg_replace( '/!.*/', '', $file );
      $parsed = preg_replace( '/||([wd]+(?:.[w]+)+)(?:[^$=~].*)/', '*://*.$1/*', $parsed ); 
    }
    $output = array_filter( explode( "n", $parsed ), function($url){
      return preg_match('/^*://*.[wd-]+.[w]+/*$/', $url);
    });
    return array_values(array_unique($output));
  }

I’ve noticed that the output content is truncated like just one file is processed, but what I need is to join the three files to manipulate them. How I can achive this?

Answer

The scope of $parsed is limited to the foreach loop, so $output only contains results from the last iteration of the loop. You should define $output before the loop, and append the results of each iteration to it.

<?php
$filters = ["https://example.com/file.txt", "https://example.com/file1.txt", "https://example.com/file3.txt"];

function parseFilterLists($filters)
{
    // Define a buffer for the output
    $output = [];
    foreach ($filters as $filter)
    {
        $file   = file_get_contents($filter);
        $parsed = preg_replace('/!.*/', '', $file);
        $parsed = preg_replace('/||([wd]+(?:.[w]+)+)(?:[^$=~].*)/', '*://*.$1/*', $parsed);

        // Get the output for the file we're working on in this iteration
        $currOutput = array_filter(explode("n", $parsed), function ($url) {
            return preg_match('/^*://*.[wd-]+.[w]+/*$/', $url);
        });

        // Append the output from the current file to the output buffer
        $output = array_merge($output, $currOutput);
    }

    // Return the unique results
    return array_unique($output);
}