Return an array of CSS selectors that have certain properties.

search-css.php

<?php

/**
 * Return an array of CSS selectors that have certain properties.
 *
 * Example: fjarrett_search_css( 'font-family: "Open Sans"' )
 * Result: array( 'h1', 'h2', 'h3', 'h4', 'h5', 'p', 'blockquote' );
 *
 * @param  string $path
 * @param  string $search
 *
 * @return array
 */
function fjarrett_search_css( $path, $search ) {

	if ( ! is_readable( $path ) ) {

		return array();

	}

	$array = array();
	$css   = file_get_contents( $path );
	$css   = preg_replace( '/^(\s)*(\/|\*|\#|\-|\>|\=).*(\r\n|\r|\n)?/m', '', $css ); // Strip comments
	$css   = array_map( 'trim', explode( '}', $css ) ); // Parse rule blocks

	foreach ( $css as $rule ) {

		$parts = array_map( 'trim', explode( '{', $rule ) ); // Parse rule

		if (
			isset( $parts[1] ) // Must have a property
			&&
			false === strpos( $parts[0], '@' ) // No imports, media queries, etc
		) {

			$array[ $parts[0] ] = isset( $array[ $parts[0] ] ) ? $array[ $parts[0] ] . $parts[1] : $parts[1];

		}

	}

	$results = array_keys( preg_grep( "/{$search}/i", $array ) ); // Find case-insensitive matches
	$results = explode( ',', implode( ',', $results ) ); // Normalize the results

	return array_map( 'trim', array_unique( $results ) );

}