OreLang

OreLang.java

package com.example;

import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.stream.Collectors;

import com.fasterxml.jackson.databind.ObjectMapper;

public class OreLang {
    HashMap<String, Object> vars = new HashMap<>();

    private Object eval(Object o) {
        if (o instanceof List) {
            System.out.println("Running: " + o);
            Object result = doRun((List<?>) o);
            System.out.println("Result: " + o + " : " + result + " : " + vars);
            return result;
        } else {
            return o;
        }
    }

    private Object doRun(List<?> list) {
        String op = (String) list.get(0);
        List<?> args = list.subList(1, list.size());
        switch (op) {
            case "set":
                vars.put((String) args.get(0), eval(args.get(1)));
                return null;
            case "get":
                return vars.get(args.get(0));
            case "+":
                return (Integer) eval(args.get(0)) + (Integer) eval(args.get(1));
            case "=":
                return eval(args.get(0)) == eval(args.get(1));
            case "until":
                while (!(Boolean) eval(args.get(0))) {
                    eval(args.get(1));
                }
                return null;
            case "step":
                List<Object> collect = args.stream()
                                           .map(this::eval)
                                           .collect(Collectors.toList());
                return collect.get(collect.size() - 1);
        }
        throw new RuntimeException("Unknown operation: " + op);
    }

    public static void main(String[] args) throws IOException {
        String source = "[\"step\",\n"
                        + "  [\"set\", \"i\", 10],\n"
                        + "  [\"set\", \"sum\", 0],\n"
                        + "  [\"until\", [\"=\", [\"get\", \"i\"], 0], [\n"
                        + "    \"step\",\n"
                        + "    [\"set\", \"sum\", [\"+\", [\"get\", \"sum\"], [\"get\", \"i\"]]],\n"
                        + "    [\"set\", \"i\", [\"+\", [\"get\", \"i\"], -1]]\n"
                        + "  ]],\n"
                        + "  [\"get\", \"sum\"]\n"
                        + "]\n";
        ObjectMapper objectMapper = new ObjectMapper();
        Object script = objectMapper.readValue(source, Object.class);
        Object result = new OreLang().eval(script);
        System.out.println("RESULT: " + result);
    }
}