jmustache

Introduction to jmustache

JMustache is a Java-based implementation of the Mustache template language, an unopinionated logic-less template syntax that is simple to implement across different programming languages. This library allows developers to integrate Mustache templating into their Java applications with minimal overhead.

Motivations Behind JMustache

JMustache was created with several key motivations in mind:

• Zero Dependencies: JMustache is designed to have no external dependencies, making it extremely lightweight and easy to include in any Java project. You can just add this library and start using Mustache templates right away.

• Platform Versatility: Its limited demands on the Java Virtual Machine (JVM) make it suitable for different environments, including Android or other restricted JVMs. Moreover, it allows working with nested maps to provide data, bypassing reflection if necessary.

• Tool Compatibility: The library is compatible with tools like Proguard and JarJar. While it can access data reflectively if needed, it avoids any other internal reflection, ensuring smooth usage alongside these tools.

• Simple API: The core API is minimal, focusing on two essential methods—compile and execute. These methods allow you to compile templates and execute them on data provided in a context.

These motivations culminate in a product that is user-friendly, lightweight, and efficient.

Getting Started

JMustache can be easily incorporated into your project. It is available on Maven Central, allowing you to add it as a dependency like so:

<dependency>
    <groupId>com.samskivert</groupId>
    <artifactId>jmustache</artifactId>
    <version>1.15</version>
</dependency>

Alternatively, you can download the pre-built JAR file from the Maven repository and include it directly in your project's classpath.

Using JMustache

Working with JMustache is straightforward. You provide your template as a String or through a Reader, and JMustache returns a Template object. This object can then be executed with any Java object as the context. Here is a basic example illustrating this:

String templateText = "One, two, {{three}}. Three sir!";
Template template = Mustache.compiler().compile(templateText);
Map<String, String> data = new HashMap<>();
data.put("three", "five");
System.out.println(template.execute(data));
// Outputs: "One, two, five. Three sir!"

For more serious usage involving input/output streams, you can use Reader and Writer with the execute method for enhanced flexibility.

Features and Extensions

JMustache extends standard Mustache template features to provide enhanced functionality:

• Partials and Lambdas: Supports partial templates for reusability and lambdas for dynamic content manipulation.

• Default Values: Flexibility in handling unresolved or null variables through defaultValue() and nullValue() methods.

• Special Variables: Offers special variables like this and -first to handle iteration within contexts effectively.

• Custom Escaping and Formatting: Customize escaping rules and object formatting to suit diverse applications or output formats beyond HTML.

Performance and Limitations

JMustache is designed to parse templates separately from their execution, optimizing repeated template use. Variables are specialized based on context and class to speed up repeated executions.

However, the library limits delimiter customization within templates to one or two characters, simplifying the parser complexity.

Thread Safety

JMustache ensures thread-safe operations when compiling templates and executing them by using default settings or ensuring custom implementations are thread-safe. It is safe to compile templates or execute them across multiple threads, provided the context is immutably maintained.

In conclusion, JMustache offers a robust and efficient solution for integrating Mustache templates within Java applications, making it a valuable tool for developers who need powerful yet minimalist templating capabilities.