refl

Simple embeddable scripting language for Java 11+ and Android

---

Installation

Gradle

implementation 'ru.rofleksey.refl:refl:0.0.6'

Maven

<dependency>
    <groupId>ru.rofleksey.refl</groupId>
  <artifactId>refl</artifactId>
  <version>0.0.6</version>
</dependency>

Usage

Declare functions and variables via context and run script.

import ru.rofleksey.refl.lang.Refl;
import ru.rofleksey.refl.lang.ReflContext;
import ru.rofleksey.refl.lang.Value;
import ru.rofleksey.refl.lang.error.EvalError;
import ru.rofleksey.refl.lang.error.ParseError;
import ru.rofleksey.refl.lang.value.FunctionValue;
import ru.rofleksey.refl.lang.value.NilValue;
import ru.rofleksey.refl.lang.value.NumberValue;

import java.util.List;
import java.util.Map;

public class Main {
    public static void main(String[] args) throws EvalError, ParseError {
        var ctx = ReflContext.empty();

        ctx.setVar("x", new NumberValue(5));
        ctx.setVar("print", new FunctionValue("print") {
            @Override
            public Value call(ReflContext ctx, Value thisValue, List<Value> args, Map<String, Value> namedArgs) {
                var prefix = namedArgs.get("prefix").toString();
                args.forEach(it -> System.out.println(prefix + it.toString()));
                return NilValue.INSTANCE;
            }
        });

        var executor = Refl.compile("while x > 0 \n print(x, prefix ~ '>') \n x-- \n end");
        var result = executor.execute(ReflContext.empty());
    }
}

Language

• operators: +, -, *, /, %, =, +=, -=, *=, /=, %=, ==, !=, <, <=, >, >=, &, |, !, ??, <<
• keywords: if, while, end, fun, scope
• types: number (double), string, nil, function, object
• built-in functions:
  • exit (stops execution, returns first argument or nil)
  • wait (waits for ReflContext.notifyCtx() call)
  • sleep (calls Thread.sleep with first argument)
  • random, floor, ceil, round
  • string, number (conversion)
• logical operators return 1 or 0

Syntax

# variable definitions
var = 1

# conditions
if condition1
  body1
  body2
elif condition2
  body1
  body2
else
  body1
  body2
end

# loops
while condition
  body1
  body2
end

# functions
fun fact
  result = 1
  i = 2

  while i <= it
    result *= i
    i++
  end

  result
end

fun concat
  if args.length == 0
    << nil
  end

  if args.length == 1
    << args[0]
  end

  result = it
  separator = args.separator ?? ''

  i = 1
  while i < args.length
    result += separator + args[i]
    i++
  end

  result
end

# scope (singleton struct)
scope Math
  PI = 3.14

  fun min
    result = it
    i = 1

    while i < args.length
      if args[i] < result
        result = args[i]
      fi
      i++
    end

    result
  end
  ...
end

pi = Math.PI
z = Math.min(x, y)