Starlasu Kotlin

Starlasu Kotlin provides the infrastructure for building custom, possibly mutable, Abstract Syntax Trees (ASTs).
It supports both Kotlin and Java, and integrates smoothly with ANTLR, though it can also be used standalone.

Starlasu stands for Star Language Support — a family of libraries available for multiple languages, including Python, TypeScript, and C#.

Starlasu Kotlin (previosuly called Kolasu) Version Overview

Supported JDKs

Tested with JDK 11, 17, and 21.
Other intermediate versions are expected to work as well.

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Documentation

• Concepts and Principles: Starlasu documentation — shared across all Starlasu libraries.
• API Reference: Javadoc for Starlasu Kotlin.

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What Is It Used For?

Starlasu is used to implement:

• Parsers
• Editors
• Transpilers
• Code analysis tools

It serves as a general foundation for projects that need to manipulate or generate language structures.

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Key Features

Extend your AST classes from Node to automatically gain:

• Navigation: Traverse, search, and modify the AST with utility methods.
• Printing: Output ASTs as XML, JSON, or parse trees.
• LionWeb Interoperability: Export ASTs and languages (i.e., metamodels) to LionWeb.
• Name Resolution: Built-in utilities for named elements and reference resolution.
• Automatic Structure Discovery: Starlasu introspects your AST — all properties and tree structure are detected automatically.

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Background

Starlasu began as a small framework to support building languages with ANTLR and Kotlin.
It has since evolved into a modular, cross-language toolkit used at Strumenta in both open-source and commercial projects for transpilers, interpreters, compilers, and related tools.

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Installation

Add the dependency from Maven Central:

dependencies {
    implementation "com.strumenta.starlasu:starlasu-core:1.7.x"
}

Performance benchmarks

The lionweb module contains JMH microbenchmarks for the model-conversion hot paths (importModelFromLionWeb, exportModelToLionWeb, tree traversal).

# Run all benchmarks
./gradlew :lionweb:jmh

# Run a specific class
./gradlew :lionweb:jmh --include "ImportModelBenchmark"

# Run with GCProfiler (allocation tracking) via the fat jar
./gradlew :lionweb:jmhJar
java -jar lionweb/build/libs/lionweb-jmh.jar ImportModelBenchmark

See lionweb/README.md for the full benchmark documentation.

How to format code

Code Formatting

Format the code using:

./gradlew ktlintFormat

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Projects Using Starlasu / Kolasu

Starlasu (and its predecessor Kolasu) are used in several internal and commercial projects developed at Strumenta.

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Releasing a New Version

If you need to publish a new release:

1. Set up GPG keys

   brew install gnupg
   gpg --gen-key
   

   (no passphrase needed)
   Export your keys:

   gpg --keyring secring.gpg --export-secret-keys > ~/.gnupg/secring.gpg
   

2. Configure credentials
   Add your Sonatype credentials to ~/.gradle/gradle.properties:

   ossrhTokenUsername=your_username
   ossrhTokenPassword=your_password
   

3. Publish the release

   ./gradlew release
   

Releases are handled automatically once triggered.

For detailed setup instructions, see
Publishing your first open-source library with Gradle.