Automatically search and replace link in content (pages/posts)?

Question

The users of my site mainly share documents by inserting links into content (pages/posts) using the built in editor. These files include everything from pdfs to word documents. The users currently get/copy these links from a php file manager like FileRun. My goal is to have the users instead use a path from mapped network drive such as \testdrive\Folder1\Folder2\test.txt. The following function has been written to handle replacing the mapped network drive files to an internet link such as "http://page.test.org/files/".

<?php
function test_test_url_parse($string)
{
// Called by test_test_url_parse_wrapper()
// The nature of preg_replace means this needs a seperate function
    $bits=explode("\\",$string);
    $bobs=array();
    foreach ($bits as $bit)
    {
        $bobs[]=urlencode($bit);
    }
    return "\"http://page.test.org/files/".implode("/",$bobs)."\"";
}

function test_test_url_parse_wrapper($string)
{
//Finds/replaces UCNs with URLs in the provided string. 
    $pattern1="~\"[a-z]{1}:\\\([^\"]+)\"~ie";
    return preg_replace($pattern1, "test_test_url_parse('$1')", $string);
}
?>

Where could I put a function like this to automatically look through the content of a page or a post and replace the filepath accordingly? Would there theoretically be any way to put this just in the child theme? Currently when I upload media such as photos, it is already putting the files into the path "http://page.test.org/files/". I'm really looking for have function go through the post/page content and perform essentially a constant "search and replace"

Answer 1

There is somewhat similar answer in the below mentioned link:

Removing any and all inline styles from the_content()

where some inline style are being removed with the help of preg_replace and wordpress hooks (wp_insert_post_data & the_content).

Similarly any part of the content can be modified with the as the same done in this (Removing any and all inline styles from the_content()) case.

Answer 2

I know this is an old question, but it was bumped to the homepage (for some reason).

I wouldn't do it constantly, since this would check all the page every time a page is loaded, which would be a lot of redundant operations, when users are simply browsing around.

I would do it on the save_post-hook.

As such:

function custom_check_URL( $post_ID, $post, $update ) {

  if ( 'publish' === $post->post_status || 'page' === $post->post_type) {
    // CHECK AND MODIFY YOUR URL'S HERE. 
  }
}
add_action( 'save_post', 'custom_check_URL', 10, 3 );

I'm not 100% certain what you were checking for or replacing it with, so I didn't include it in this answer.