woocommerce add to cart button for product variations

//new code added here

function find_valid_variations() {
    global $product;

    $variations = $product->get_available_variations();
    $attributes = $product->get_attributes();
    $new_variants = array();

    // Loop through all variations
    foreach( $variations as $variation ) {

        // Peruse the attributes.

        // 1. If both are explicitly set, this is a valid variation
        // 2. If one is not set, that means any, and we must 'create' the rest.

        $valid = true; // so far
        foreach( $attributes as $slug => $args ) {
            if( array_key_exists("attribute_$slug", $variation['attributes']) && !empty($variation['attributes']["attribute_$slug"]) ) {
                // Exists

            } else {
                // Not exists, create
                $valid = false; // it contains 'anys'
                // loop through all options for the 'ANY' attribute, and add each
                foreach( explode( '|', $attributes[$slug]['value']) as $attribute ) {
                    $attribute = trim( $attribute );
                    $new_variant = $variation;
                    $new_variant['attributes']["attribute_$slug"] = $attribute;
                    $new_variants[] = $new_variant;
                }

            }
        }

        // This contains ALL set attributes, and is itself a 'valid' variation.
        if( $valid )
            $new_variants[] = $variation;

    }

    return $new_variants;
}






function woocommerce_variable_add_to_cart(){
    global $product, $post;

    $variations = find_valid_variations();

    // Check if the special 'price_grid' meta is set, if it is, load the default template:
    if ( get_post_meta($post->ID, 'price_grid', true) ) {
        // Enqueue variation scripts
        wp_enqueue_script( 'wc-add-to-cart-variation' );

        // Load the template
        wc_get_template( 'single-product/add-to-cart/variable.php', array(
                'available_variations'  => $product->get_available_variations(),
                'attributes'            => $product->get_variation_attributes(),
                'selected_attributes'   => $product->get_variation_default_attributes()
            ) );
        return;
    }

    // Cool, lets do our own template!
    ?>
    <table class="variations variations-grid" cellspacing="0">
        <tbody>
            <?php
            foreach ($variations as $key => $value) {
                if( !$value['variation_is_visible'] ) continue;
            ?>
            <tr>
                <td>
                    <?php foreach($value['attributes'] as $key => $val ) {
                        $val = str_replace(array('-','_'), ' ', $val);
                        printf( '<span class="attr attr-%s">%s</span>', $key, ucwords($val) );
                    } ?>
                </td>
                <td>
                    <?php echo $value['price_html'];?>
                </td>
                <td>
                    <?php if( $value['is_in_stock'] ) { ?>
                    <form class="cart" action="<?php echo esc_url( $product->add_to_cart_url() ); ?>" method="post" enctype='multipart/form-data'>
                        <?php woocommerce_quantity_input(); ?>
                        <?php
                        if(!empty($value['attributes'])){
                            foreach ($value['attributes'] as $attr_key => $attr_value) {
                            ?>
                            <input type="hidden" name="<?php echo $attr_key?>" value="<?php echo $attr_value?>">
                            <?php
                            }
                        }
                        ?>
                        <button type="submit" class="single_add_to_cart_button btn btn-primary"><span class="glyphicon glyphicon-tag"></span> Add to cart</button>
                        <input type="hidden" name="variation_id" value="<?php echo $value['variation_id']?>" />
                        <input type="hidden" name="product_id" value="<?php echo esc_attr( $post->ID ); ?>" />
                        <input type="hidden" name="add-to-cart" value="<?php echo esc_attr( $post->ID ); ?>" />
                    </form>
                    <?php } else { ?>
                        <p class="stock out-of-stock"><?php _e( 'This product is currently out of stock and unavailable.', 'woocommerce' ); ?></p>
                    <?php } ?>
                </td>
            </tr>
            <?php } ?>
        </tbody>
    </table>
    <?php
}