Aviator: A Lightweight High‑Performance JVM Expression Engine and Script Language

Today we introduce Aviator, a lightweight rule engine that started as a high‑performance JVM expression engine and, since version 5.0.0, has become AviatorScript—a lightweight scripting language running on the JVM (including Android).

Key features of Aviator include support for basic types (numbers, strings, regex, booleans), full Java operator support, first‑class functions with closures, built‑in bigint/decimal types with operator overloading ( +-*/ ), complete script syntax (multiline data, conditionals, loops, lexical scope, exception handling), functional programming with Sequence, a lightweight module system, seamless Java method invocation, extensive customization for sandboxing or full‑language use, and high performance via ASM bytecode generation or an interpreter mode for non‑standard JVM platforms.

Typical scenarios are rule evaluation, formula calculation, dynamic script control, and ELT on collection data.

Aviator Basic Usage

Basic Expression

To use Aviator, add the Maven dependency:

<dependency>
    <groupId>com.googlecode.aviator</groupId>
    <artifactId>aviator</artifactId>
    <version>5.3.3</version>
</dependency>

Then evaluate an expression:

// returns 16
Long r = (Long) AviatorEvaluator.execute("2 * (3 + 5)");

For better performance, compile the expression first:

Expression expression = AviatorEvaluator.compile("2 * (3 + 5)");
Long r = (Long) expression.execute();

Aviator handles numbers, strings, booleans, and supports most arithmetic, logical, comparison, bitwise, ternary, and regex operators.

Expression Variables

Variables can be passed as parameters:

Long a = 12L;
Boolean r = (Boolean) AviatorEvaluator.exec("a > 10", a);

Lists and objects can also be used as the environment:

List<Long> a = new ArrayList<>();
a.add(12L);
a.add(20L);
Boolean r = (Boolean) AviatorEvaluator.exec("a[0] > 10", a);

public static class Person {
    private String name;
    private Integer age;
}
Person p = new Person("movee", 25);
Boolean r2 = (Boolean) AviatorEvaluator.exec("a.age > 10", p);

Map
env = new HashMap<>();
env.put("person", new Person("movee", 25));
env.put("a", 20L);
Object result = AviatorEvaluator.execute("person.name", env);

Using Functions

Aviator provides many built‑in functions:

// round
Long r1 = (Long) AviatorEvaluator.execute("math.round(4.3)");
// string length
Long r2 = (Long) AviatorEvaluator.execute("string.length('hello')");
// sequence list
Object r3 = AviatorEvaluator.execute("seq.list(1,2,3)");

Custom functions can be created by extending AbstractFunction and registering them:

public class AddFunction extends AbstractFunction {
    @Override
    public AviatorObject call(Map
env, AviatorObject arg1, AviatorObject arg2) {
        long num1 = FunctionUtils.getNumberValue(arg1, env).longValue();
        long num2 = FunctionUtils.getNumberValue(arg2, env).longValue();
        return AviatorLong.valueOf(num1 + num2);
    }
    @Override
    public String getName() { return "add"; }
}
AviatorEvaluator.addFunction(new AddFunction());
long sum = (Long) AviatorEvaluator.getInstance().execute("add(3,4)");

AviatorScript

Since the upgrade, Aviator can run full scripts:

// returns 1
Object r = AviatorEvaluator.execute("if (true) { return 1; } else { return 2; }");

Scripts are stored in files with the .av extension, e.g., hello.av :

if (a > 10) {
    return 10;
} else {
    return a;
}

Execute the script with parameters:

Map
env = new HashMap<>();
env.put("a", 30);
Expression exp = AviatorEvaluator.getInstance().compileScript("./hello.av", true);
Object result = exp.execute(env);

Official documentation: https://github.com/killme2008/aviatorscript