A fast MoLang parser, compiler, and runtime for Java.

MoLang is Minecraft Bedrock's expression language for animations, particles, and render controllers. MoJava parses MoLang source, compiles it to JVM bytecode, and evaluates the result — so a script that's compiled once and reused runs at hand-written-Java speed.

Requires Java 17+.

• Compiles to JVM bytecode (via ASM) into a GC-reclaimable hidden class — no tree-walking at eval time.
• Allocation-free numeric evaluation. Numeric scripts evaluate straight to a primitive double with zero heap allocation per call (executeDouble), so there's no per-frame GC pressure.
• math.* inlined to java.lang.Math, repeated variable reads cached, and variable/temp reads resolved to slot indices instead of map lookups.

repositories {
    maven("https://repo.opencollab.dev/maven-releases/")
}
dependencies {
    implementation("org.cloudburstmc:mojava:0.0.1")
}

import org.cloudburstmc.mojava.MoJava;
import org.cloudburstmc.mojava.compiler.MoScript;
import org.cloudburstmc.mojava.runtime.MoRuntime;
import org.cloudburstmc.mojava.runtime.value.DoubleValue;

MoRuntime runtime = MoJava.createRuntime();

// Seed a variable and register a query the script can read
runtime.getEnvironment().variable.setDirectly("speed", new DoubleValue(1.5));
runtime.getEnvironment().query.addDoubleFunction("life_time", params -> 0.5);

// Compile once...
MoScript script = runtime.compile(MoJava.parse("math.sin(q.life_time * 90) * v.speed"));

// ...evaluate as often as you like (allocation-free for numeric scripts)
double value = runtime.executeDouble(script);

For a one-off evaluation, skip the caching: runtime.execute(MoJava.parse(code)) returns a MoValue (call .asDouble() or .asString() on it).

v./variable., t./temp., q./query., and c./context. resolve against the runtime's environment:

var env = runtime.getEnvironment();

// Variables (read/write from scripts; persist across evals)
env.variable.setDirectly("health", new DoubleValue(20));

// Queries — host callbacks the script can read or call
env.query.addFunction("entity_name", params -> new StringValue("creeper")); // any MoValue
env.query.addDoubleFunction("distance", params -> 12.5);                     // numeric fast path

Register numeric queries with addDoubleFunction: it returns a primitive double, skipping the Double/DoubleValue boxing a generic Function incurs, so query reads on the numeric path stay allocation-free. Use addFunction for queries that return strings or structs.

./gradlew build      # compile + run tests
./gradlew jmh        # run the benchmark suite (cross-engine + per-workload)

Licensed under the Apache License 2.0.