generating_bg_image_based_on_files.php

<?php
require  '../vendor/autoload.php';

$Directory = new RecursiveDirectoryIterator(__DIR__ . '\svg');
$Iterator = new RecursiveIteratorIterator($Directory);
$svgs = new RegexIterator($Iterator, '/^.+\.svg$/i', RecursiveRegexIterator::GET_MATCH);
echo '<pre>';
foreach ($svgs as $svg) {
    [$name, $extension] = explode('.', basename($svg[0]));
    $content = base64_encode(file_get_contents($svg[0]));
    $prefix = '    background-image: url("data:image/svg+xml;base64,';
    $suffix = '");' . PHP_EOL;
    echo ".$name {" . PHP_EOL;
    echo $prefix . $content . $suffix;
    echo '}' . PHP_EOL;
}
echo '</pre>';

generating_html_based_on_generated_css.php

<?php
require  '../vendor/autoload.php';

$Directory = new RecursiveDirectoryIterator(__DIR__ . '\svg');
$Iterator = new RecursiveIteratorIterator($Directory);
$svgs = new RegexIterator($Iterator, '/^.+\.svg$/i', RecursiveRegexIterator::GET_MATCH);
foreach ($svgs as $svg) {
    [$name, $extension] = explode('.', basename($svg[0]));
    echo  '<span class="icon ' . $name . '"></span>' . PHP_EOL;
}