<?php
    if ( ! function_exists( 'woocommerce_template_loop_add_to_cart' ) ) {

    /**
     * Get the add to cart template for the loop.
     *
     * @subpackage  Loop
     */
    function woocommerce_template_loop_add_to_cart( $args = array() ) {
        global $product;

        if ( $product ) {
            $defaults = array(
                'quantity' => 1,
                'class'    => implode( ' ', array_filter( array(
                        'button',
                        'product_type_' . $product->product_type,
                        $product->is_purchasable() && $product->is_in_stock() ? 'add_to_cart_button' : '',
                        $product->supports( 'ajax_add_to_cart' ) ? 'ajax_add_to_cart' : ''
                ) ) )
            );

            $args = apply_filters( 'woocommerce_loop_add_to_cart_args', wp_parse_args( $args, $defaults ), $product );

            wc_get_template( 'loop/add-to-cart.php', $args );
        }
    }
}
?>