BFInterpreter.java

import java.util.HashMap;
import java.util.Map;
import java.util.Arrays;
import java.util.logging.Level;
import java.util.logging.Logger;

import java.io.*;
import java.util.*;
import java.nio.charset.Charset;

import org.antlr.runtime.TokenStream;
import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;

import org.apache.commons.io.IOUtils;

public class BFInterpreter extends BrainfuqBaseVisitor {

    //private static Logger logger = Logger.getLogger(BFInterpreter.class.getName());
    
     //ANSI COLOURS
    public static final String ANSI_RESET = "\u001B[0m";
    public static final String ANSI_RED = "\u001B[31m";
    public static final String ANSI_GREEN = "\u001B[32m";
    public static final String ANSI_CYAN_BACKGROUND = "\u001B[46m";

    Boolean isMoving = false;

    private int LENGTH = 65443;
    byte[] tape = new byte[LENGTH];
    int dataPointer = 0;

    //For the input
    private Scanner sc = new Scanner(System.in);


    @Override
    public Object visitTop(BrainfuqParser.TopContext ctx) {

//        System.out.print("Enterted Top\n");
        visitChildren(ctx);
        return null;
    }

    @Override
    public Object visitProg(BrainfuqParser.ProgContext ctx) {

//        System.out.print("Enterted Prog\n");
        visitChildren(ctx);
        return null;
    }


    @Override
    public Object visitOps(BrainfuqParser.OpsContext ctx) {

//        System.out.print("Enterted Ops\n");
        switch (ctx.op.getType()) {
            case BrainfuqLexer.INPUT:
                tape[dataPointer] = (byte) sc.next().charAt(0);
                break;
            case BrainfuqLexer.OUTPUT:
                if (isMoving) {
                    System.out.print((char) tape[dataPointer]);
                } else {
                    System.out.print(ANSI_GREEN + (char) tape[dataPointer] + ANSI_RESET);
                }
                break;
            case BrainfuqLexer.INC:
                tape[dataPointer]++;
                break;
            case BrainfuqLexer.DEC:
                tape[dataPointer]--;
                break;
            case BrainfuqLexer.P_INC:
                dataPointer = (dataPointer == LENGTH-1) ? 0 : dataPointer + 1;
                break;
            case BrainfuqLexer.P_DEC:
                dataPointer = (dataPointer == 0) ? LENGTH-1 : dataPointer - 1;
                break;
        }

        return null;
    }

    @Override
    public Object visitLoop(BrainfuqParser.LoopContext ctx) {

//        System.out.print("Enterted Loop\n");
        while (tape[dataPointer] != 0) {
            visitChildren(ctx);
        }


        return null;

    }

    


    public static void main(String[] args) throws IOException {
        
        BFInterpreter bfInt = new BFInterpreter();

        final String BRAINFUCK = "Brain" + ANSI_RED + "fuck" + ANSI_RESET;
        final String HELPCODE = ANSI_CYAN_BACKGROUND + ":help" + ANSI_RESET;
        final String BFHEADER = ANSI_RED + "BF" + ANSI_RESET;


        if (args[0].equals("-i")) {

            //Stack<String> commandStack = new Stack<String>();
    
            Scanner commands = new Scanner(System.in);
            System.out.print("\n    Welcome to " + BRAINFUCK + " REPL(an interactive programming environment) :)\n");
            System.out.print("    " + BRAINFUCK + " is trivial yet very difficult to write.\n    If you want to get a hint of the grammar, just type in " + HELPCODE + "\n\n");   

            while (true) {
                System.out.print(BFHEADER + " ⚡️  ");
                String command = commands.next();
                
                //TODO: Implement a Command Stack and detect arrow keys to select through previous commands
                //if (command.equals("^[[A")) {
                    //System.out.print("foooo");
                //}
                //commandStack.push(command);
                
                System.out.print("\n    ");

                if (command.equals(":help") || command.equals(":h")) {

                    System.out.print("> : Move data pointer one cell to the right\n" +
                                     "    < : Move data pointer one cell to the left\n" +
                                     "    + : Increment the value at the data pointer\n" +
                                     "    - : Decrement the value at the data pointer\n" +
                                     "    . : Print out the value at the data pointer (as ASCII)\n" +
                                     "    , : Accept a byte of input and store it as the value at the pointer\n" +
                                     "    [ : Jump to the matching ] unless the value at the pointer is 0\n" +
                                     "    ] : Jump backwards to the matching [ unless the value at the data pointer is not 0\n\n");

                } else if (command.equals(":emoji") || command.equals(":e")) {

                    System.out.print("👉  : Move data pointer one cell to the right\n" +
                                     "    👈  : Move data pointer one cell to the left\n" +
                                     "    👆  : Increment the value at the data pointer\n" +
                                     "    👇  : Decrement the value at the data pointer\n" +
                                     "    🌚  : Print out the value at the data pointer (as ASCII)\n" +
                                     "    🌝  : Accept a byte of input and store it as the value at the pointer\n" +
                                     "    🌜  : Jump to the matching 🌛  unless the value at the pointer is 0\n" +
                                     "    🌛  : Jump backwards to the matching 🌜  unless the value at the data pointer is not 0\n\n");
        
                } else if (command.equals(":quit") || command.equals(":q")) {
                    System.out.print("It's been fun playing with you! See you next time!\n\n");
                    return;
                } else {

                    command = command.replaceAll("🌝", ",");
                    command = command.replaceAll("🌚", ".");
                    command = command.replaceAll("👆", "+");
                    command = command.replaceAll("👇", "-");
                    command = command.replaceAll("👉", ">");
                    command = command.replaceAll("👈", "<");
                    command = command.replaceAll("🌜", "[");
                    command = command.replaceAll("🌛", "]");

                    ANTLRInputStream input = new ANTLRInputStream(command);
                    BrainfuqLexer lexer = new BrainfuqLexer(input);
                    CommonTokenStream tokens = new CommonTokenStream(lexer);
                    BrainfuqParser parser = new BrainfuqParser(tokens);
                    bfInt.visit(parser.top());
                    System.out.print("\n\n");

                    //Resetting the state for the next repl
                    bfInt.dataPointer = 0;
                    bfInt.tape = null;
                    bfInt.tape = new byte[bfInt.LENGTH];
                }

            }
                
        } else {
            try {
            FileInputStream inStream = new FileInputStream(args[0]);

            //Temporary fix for Hanoi Tower moving program
            if (args[0].equals("Hanoi.bf")) {
                bfInt.isMoving = true;
            }
            String code = IOUtils.toString(inStream, Charset.defaultCharset());
            code = code.replaceAll("🌝", ",");
            code = code.replaceAll("🌚", ".");
            code = code.replaceAll("👆", "+");
            code = code.replaceAll("👇", "-");
            code = code.replaceAll("👉", ">");
            code = code.replaceAll("👈", "<");
            code = code.replaceAll("🌜", "[");
            code = code.replaceAll("🌛", "]");

            final ANTLRInputStream input = new ANTLRInputStream(code);
            BrainfuqLexer lexer = new BrainfuqLexer(input);
            CommonTokenStream tokens = new CommonTokenStream(lexer);
            BrainfuqParser parser = new BrainfuqParser(tokens);
            bfInt.visit(parser.top());

//            logger.log(Level.INFO, "p: {0}; tape: {1}", new Object[] {
//                    bfInt.p,
//                    Arrays.toString(bfInt.tape)
//            });
            } catch (IOException foo) {
                foo.printStackTrace();
            }

        }

    }
}