Used to insert a CSS file <link> tag once no matter how often it's called. HTTP/2 inline CSS is why I wrote this.

inline_css_file.php

<?php

// This is defined somewhere high up in functions.php
// $GLOBALS['cnmd_inline_css_record'] = array();


/**
 * Used to shoot out css files in-line, and only once per file. Uses the CSS ID as an 
 * index into an array to prevent dupes.
 * 
 * @param $handle
 * @param $path
 *
 * @return string
 */
function cnmd_get_inline_css_file( $handle, $path ) {
	if ( !isset($GLOBALS['cnmd_inline_css_record'][$handle] ) ) {
		$GLOBALS['cnmd_inline_css_record'][$handle] = true;
		return '<link rel="stylesheet" id="' . $handle . '" href="' . $path . '" media="all">';
	}
	return '';
}