Extract database and other constants from a wp-config.php file without "including" it.

wordpress-config-extract.php

<?php
/**
 * Extract key and value from all "define" constants in a wp-config.php file using built-in php tokenizer functions.
 * Does not "include" the file so it won't pollute the current scope or cause side effects.
 *
 * NOTE: Works with constants defined as string, bool or number
 * Method can extract values from statements like:
 * define( 'DB_NAME', 'wordpress' );
 * define('WP_DEBUG', true);
 * define('SOMEINT', 1234567);
 *
 * Any defined using a function or magic var ( __FILE__ or __DIR__ ) will not decode properly.
 * define( 'ABSPATH', dirname( __FILE__ ) . '/' );
 * The value requires php to interpret it.
 * You'll get NULL for these values.
 *
 * @param $pathToFile
 * @return array
 */
function extractNamedConstants($pathToFile)
{
    if(is_readable($pathToFile)){
        $tokens = token_get_all(file_get_contents($pathToFile));
    }else{
        throw new InvalidArgumentException("Cannot read file. Check permissions.");
    }

    //useful for debugging @see http://php.net/manual/en/function.token-get-all.php
    //foreach($tokens as &$token){
    //    if(is_array($token))
    //        $token[0] = token_name($token[0]) . ':' . $token[0];
    //}
    //print_r($tokens); die(__FILE__ . __LINE__);

    //list of tokens by line#
    $lineIndex = array();
    //list of lines with "define" statements.
    $defineIndex = array();
    foreach ($tokens as $index => $attribs) {
        //FYI: $attribs[0]= token_name(); $attribs[1]==value; $attribs[2]==line#
        if (is_array($attribs)) {
            $lineNum = $attribs[2];

            //group tokens by line#. (make list if it doesn't exist)
            if (!isset($lineIndex[$lineNum])) {
                $lineIndex[$lineNum] = array();
            }
            $lineIndex[$lineNum][] = $index;

            //remember a line# with a 'define' statement
            if ($attribs[0] == T_STRING && strtolower($attribs[1]) == 'define') {
                $defineIndex[] = $lineNum;
            }
        }
    }

    //loop again and consider only lines with 'define' statements
    $data = [];
    foreach ($defineIndex as $lineNum) {
        $kvp = [];
        //look on each line with a define for the key and value tokens. (Assumes one define statement per line)
        foreach ($lineIndex[$lineNum] as $tokenIndex) {
            //load token attributes
            $attribs = $tokens[$tokenIndex];

            //Look for string constant like define( 'DB_NAME', 'wordpress' );
            if ($attribs[0] == T_CONSTANT_ENCAPSED_STRING) {
                $kvp[] = trim($attribs[1], "'");
            } elseif ($attribs[0] == T_STRING && !empty($kvp)) {
                //Look for bool values like define('TEST',true);
                //Check value for functions like: define( 'ABSPATH', dirname( __FILE__ ) . '/' );
                if (function_exists($attribs[1]) && $tokens[$tokenIndex + 1] == '(') {
                    //this "define" is using a function. decoding requires parsing. Error out.
                    $kvp[] = NULL;
                } else {
                    $kvp[] = $attribs[1];
                }
            } elseif ($attribs[0] == T_LNUMBER && !empty($kvp)) {
                //Look for bool/number values like define('TEST',1);
                $kvp[] = $attribs[1];
            }
        }
        //store result. Assumes T_CONSTANT_ENCAPSED_STRING is encountered first on a line with one or more other elements after.
        $data[$kvp[0]] = $kvp[1];
    }
    return $data;
}

/*
 * Try it out!
 */
$data = extractNamedConstants(__DIR__ . '/wordpress/wp-config.php');
var_dump($data);
die();