BrainFuck interpreter/jit compiler using java's MethodHandle

BrainFuckMethodHandleCompiler.java

package org.bennydict.brainmethodfuckhandles;

import java.io.*;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.util.HashMap;
import java.util.Scanner;

public class BrainFuckMethodHandleCompiler {
    public static void main(String[] args) {
        String code = new Scanner(System.in).nextLine();

        MethodHandle compiled = compile(code);

        BrainFuckVM vm = new BrainFuckVM(System.in, System.out);

        try {
            compiled.invoke(vm);
        } catch (Throwable e) {
            throw new RuntimeException(e);
        }
    }

    static class CompileResult {
        MethodHandle result;
        String rest;

        public CompileResult(MethodHandle result, String rest) {
            this.result = result;
            this.rest = rest;
        }
    }

    static MethodHandle compile(String code) {
        CompileResult result = null;
        try {
            result = compileLoop(code);
        } catch (NoSuchMethodException e) {
            throw new NoSuchMethodError(e.toString());
        } catch (IllegalAccessException e) {
            throw new IllegalAccessError(e.toString());
        }
        if (!result.rest.isEmpty()) {
            throw new IllegalArgumentException("bad code");
        }
        return result.result;
    }

    static CompileResult compileLoop(String code) throws NoSuchMethodException, IllegalAccessException {
        MethodType type = MethodType.methodType(void.class);
        MethodHandle ret = MethodHandles.empty(type);
        HashMap<Character, String> nameMap = new HashMap<>();
        nameMap.put('>', "gt");
        nameMap.put('<', "lt");
        nameMap.put('+', "plus");
        nameMap.put('-', "minus");
        nameMap.put('.', "dot");
        nameMap.put(',', "comma");

        while (!(code.isEmpty() || code.charAt(0) == ']')) {
            MethodHandle next;
            switch (code.charAt(0)) {
                case '>':
                case '<':
                case '+':
                case '-':
                case '.':
                case ',':
                    next = MethodHandles.lookup().findVirtual(BrainFuckVM.class, nameMap.get(code.charAt(0)), type);
                    ret = MethodHandles.doWhileLoop(ret, next, MethodHandles.constant(boolean.class, false));
                    break;
                case '[':
                    CompileResult result = compileLoop(code.substring(1));
                    ret = MethodHandles.doWhileLoop(ret,
                            MethodHandles.whileLoop(null,
                                    MethodHandles.lookup().findVirtual(BrainFuckVM.class, "testNZ", MethodType.methodType(boolean.class)),
                                    result.result), MethodHandles.constant(boolean.class, false));
                    code = result.rest;
                    if (code.charAt(0) != ']') {
                        throw new IllegalArgumentException("bad code");
                    }
                    break;
                case ']':
                    break;
            }
            code = code.substring(1);
        }
        return new CompileResult(ret, code);
    }
}

class BrainFuckVM {
    private InputStream in;
    private PrintStream out;

    public BrainFuckVM(InputStream in, PrintStream out) {
        this.in = in;
        this.out = out;
    }

    private byte[] tape = new byte[30000];
    private int ptr = 0;

    void gt() {
        ptr += 1;
    }

    void lt() {
        ptr -= 1;
    }

    void plus() {
        tape[ptr] += 1;
    }

    void minus() {
        tape[ptr] -= 1;
    }

    void dot() {
        out.print((char) tape[ptr]);
    }

    void comma() {
        try {
            tape[ptr] = (byte) in.read();
        } catch (IOException e) {
            throw new IOError(e);
        }
    }

    boolean testNZ() {
        return tape[ptr] != 0;
    }
}

BRILLIANT <3

GENIUS :3