Source

File: wp-includes/comment-template.php

function get_comment_reply_link( $args = array(), $comment = null, $post = null ) {
	$defaults = array(
		'add_below'     => 'comment',
		'respond_id'    => 'respond',
		'reply_text'    => __( 'Reply' ),
		/* translators: Comment reply button text. %s: Comment author name. */
		'reply_to_text' => __( 'Reply to %s' ),
		'login_text'    => __( 'Log in to Reply' ),
		'max_depth'     => 0,
		'depth'         => 0,
		'before'        => '',
		'after'         => '',
	);

	$args = wp_parse_args( $args, $defaults );

	if ( 0 == $args['depth'] || $args['max_depth'] <= $args['depth'] ) {
		return;
	}

	$comment = get_comment( $comment );

	if ( empty( $comment ) ) {
		return;
	}

	if ( empty( $post ) ) {
		$post = $comment->comment_post_ID;
	}

	$post = get_post( $post );

	if ( ! comments_open( $post->ID ) ) {
		return false;
	}

	/**
	 * Filters the comment reply link arguments.
	 *
	 * @since 4.1.0
	 *
	 * @param array      $args    Comment reply link arguments. See get_comment_reply_link()
	 *                            for more information on accepted arguments.
	 * @param WP_Comment $comment The object of the comment being replied to.
	 * @param WP_Post    $post    The WP_Post object.
	 */
	$args = apply_filters( 'comment_reply_link_args', $args, $comment, $post );

	if ( get_option( 'comment_registration' ) && ! is_user_logged_in() ) {
		$link = sprintf(
			'<a rel="nofollow" class="comment-reply-login" href="%s">%s</a>',
			esc_url( wp_login_url( get_permalink() ) ),
			$args['login_text']
		);
	} else {
		$data_attributes = array(
			'commentid'      => $comment->comment_ID,
			'postid'         => $post->ID,
			'belowelement'   => $args['add_below'] . '-' . $comment->comment_ID,
			'respondelement' => $args['respond_id'],
			'replyto'        => sprintf( $args['reply_to_text'], $comment->comment_author ),
		);

		$data_attribute_string = '';

		foreach ( $data_attributes as $name => $value ) {
			$data_attribute_string .= " data-${name}=\"" . esc_attr( $value ) . '"';
		}

		$data_attribute_string = trim( $data_attribute_string );

		$link = sprintf(
			"<a rel='nofollow' class='comment-reply-link' href='%s' %s aria-label='%s'>%s</a>",
			esc_url(
				add_query_arg(
					array(
						'replytocom'      => $comment->comment_ID,
						'unapproved'      => false,
						'moderation-hash' => false,
					),
					get_permalink( $post->ID )
				)
			) . '#' . $args['respond_id'],
			$data_attribute_string,
			esc_attr( sprintf( $args['reply_to_text'], $comment->comment_author ) ),
			$args['reply_text']
		);
	}

	/**
	 * Filters the comment reply link.
	 *
	 * @since 2.7.0
	 *
	 * @param string     $link    The HTML markup for the comment reply link.
	 * @param array      $args    An array of arguments overriding the defaults.
	 * @param WP_Comment $comment The object of the comment being replied.
	 * @param WP_Post    $post    The WP_Post object.
	 */
	return apply_filters( 'comment_reply_link', $args['before'] . $link . $args['after'], $args, $comment, $post );
}