Thymeleaf apply different title-patterns

I am using the latest version of thymeleaf page layouts.

I want to use the title pattern $CONTENT_TITLE - $LAYOUT_TITLE for all my pages. Therefore, I created the following layout and content files.

My layout.html file looks like

<!doctype html>
<html xmlns:th="http://www.thymeleaf.org" xmlns:layout="http://www.w3.org/1999/xhtml">
<head>
    <title layout:title-pattern="$CONTENT_TITLE - $LAYOUT_TITLE">My Company Name</title>
    <!-- some scripts and styles --->
</head>
<body>
    <!-- some content --->
</body>
</html>

My content.html looks like

<!DOCTYPE html>
<html xmlns:layout="http://www.ultraq.net.nz/thymeleaf/layout" xmlns:th="http://www.thymeleaf.org"
      layout:decorate="~{layout.html}">
<head>
    <title>
        <th:block th:if="${meta.pageTitle}" th:text="${meta.pageTitle}"></th:block>
    </title>
</head>
<body>
    <!-- some content --->
</body>
</html>

If the content page gets Newsletter as value for the property pageTitle and I call the content page in my browser, I get the correct result:

<title>Newsletter - My Company Name</title>

If my content page does not have a title, I only want to display the $LAYOUT_TITLE in my <title> tag without the leading separator -. Howerver, with my code I get

<title>- My Company Name</title>

What I want is

<title>My Company Name</title>

How can I achieve that in a simple way? As far as I know, I cant use the $CONTENT_TITLE in the layout.html and check if it is empty, or can I?

Solution

Since i could not find a way to use conditions for the title-pattern I moved away from this and used parameterizable fragments as suggested in this answer.

layout.html

<!doctype html>
<html xmlns:th="http://www.thymeleaf.org" xmlns:layout="http://www.w3.org/1999/xhtml">
<head>
    <!-- some scripts and styles --->
</head>
<body>
    <!-- some content --->
</body>
</html>

content.html

<!doctype html>
<html xmlns:layout="http://www.ultraq.net.nz/thymeleaf/layout" xmlns:th="http://www.thymeleaf.org"
      layout:decorate="~{layout.html}">

<head>
    <th:block th:replace="./fragments/page-title.html :: page-title('My Content Title')"></th:block>
</head>

<body>
    <!-- some content --->
</body>
</html>

./fragments/page-title.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head th:fragment="page-title(pageTitle)" th:remove="tag">
    <title th:text="(${pageTitle}? ${pageTitle} + ' - ' : '') + 'My Company Name'"></title>
</head>
</html>

This results in <title>My Content Title - My Company Name</title> for all pages with an additional title and <title>My Company Name</title> for all pages without an additional title (like my start page).