Function which uses regular expression to parse Microsoft Word footnotes into WordPress's Simple Footnotes format

parse-word-footnotes.php

/**
 * Function which uses regular expression to parse Microsoft Word footnotes 
 * into WordPress's Simple Footnotes format
 *
 * @param string $content post content from filter hook
 * @returns string post content with parsed footnotes
 * @link http://ben.balter.com/2011/03/20/regular-expression-to-parse-word-style-footnotes/
 */
function bb_parse_footnotes( $content ) {
    global $post;

    if ( !isset( $post ) )
    	return;

    //if we have already parsed, kick
    if ( get_post_meta($post->ID, 'parsed_footnotes') )
    	return $content;

    $content = stripslashes( $content );

    //grab all the Word-style footnotes into an array
    $pattern = '#\<a href\="\#_ftnref([0-9]+)"\>\[([0-9]+)\]\</a\> (.*)#';
    preg_match_all( $pattern, $content, $footnotes, PREG_SET_ORDER);
    
    //build find and replace arrays
    foreach ($footnotes as $footnote) {
    	$find[] = '#\<a href\="\#_ftn'.$footnote[1].'"\>\['.$footnote[1].'\]\</a\>#';
    	$replace[] = '[[ref]' . str_replace( array("\r\n", "\r", "\n"), "", $footnote[3]) . '[/ref]]';
    }
    
    //remove all the original footnotes when done
    $find[] = '#\<div\>\s*<a href\="\#_ftnref([0-9]+)"\>\[([0-9]+)\]\</a\> (.*)\s*\</div\>\s+#';
    $replace[] = '';
    
    //make the switch
    $content = preg_replace( $find, $replace, $content );
    
    //add meta so we know it has been parsed
    add_post_meta($post->ID,'parsed_footnotes', true, true);
    
    return addslashes($content);
}

add_filter( 'content_save_pre', 'bb_parse_footnotes' );