摘要

@Parser.java
@HelloWorld.java
@运行结果

Parser.java

package com.afirez.brainfuck;

import java.io.IOException;
/** 
 * Project: brainfuck
 * Author: afirez
 * Date: 2016/7/29 0029. 
 */
public class Parser {
    private Codes mCodes;
    private VM mVM; 
    
    public void run() {
        mVM.run();
    } 
   
    Parser() {
        this.mCodes = new ReadCodesFromScanner();
        mVM = new VM(mCodes.get());
    }

    Parser(Codes codes) {
        this.mCodes = codes;
        mVM = new VM(mCodes.get());
    }

    public interface Codes {
        String get();
    }

    interface CallBack {
        void execute(VM vm);
    }

    private class VM {
        public static final String TOKENS = "><+-,.[]";
        static final int STACK_SIZE = 1000;
        static final int DATAS_SIZE = 30000;

        char[] codes;
        int codePointer;

        int[] stack;
        int stackPointer;

        char[] datas;
        int dataPointer;

        CallBack[] callBacks;

        private VM(String codes) {
            this.codes = codes.toCharArray();
            stack = new int[STACK_SIZE];
            datas = new char[DATAS_SIZE];
            initCallBacks();
        }

        private void initCallBacks() {
            callBacks = new CallBack[128];
            this.callBacks['>'] = new Forward();
            this.callBacks['<'] = new Backward();
            this.callBacks['+'] = new Increment();
            this.callBacks['-'] = new Decrement();
            this.callBacks['.'] = new Output();
            this.callBacks[','] = new Input();
            this.callBacks['['] = new WhileEntry();
            this.callBacks[']'] = new WhileExit();
        }

        void run() {
            for (; this.codePointer < codes.length ; this.codePointer++) {
                this.callBacks[this.codes[this.codePointer]].execute(this);
            }
        }
    }

    private class Forward implements CallBack {
        @Override
        public void execute(VM vm) {
            vm.dataPointer++;
            vm.dataPointer %= VM.DATAS_SIZE;
        }
    }

    private class Backward implements CallBack {
        @Override
        public void execute(VM vm) {
            vm.dataPointer--;
            vm.dataPointer = (vm.dataPointer + VM.DATAS_SIZE) % VM.DATAS_SIZE;
        }
    }

    private class Increment implements CallBack {
        @Override
        public void execute(VM vm) {
            vm.datas[vm.dataPointer]++;
        }
    }

    private class Decrement implements CallBack {
        @Override
        public void execute(VM vm) {
            vm.datas[vm.dataPointer]--;
        }
    }

    private class Input implements CallBack {
        @Override
        public void execute(VM vm) {
            vm.datas[vm.dataPointer] = getChar();
        }
    }

    private class Output implements CallBack {
        @Override
        public void execute(VM vm) {
            System.out.printf("%c",vm.datas[vm.dataPointer]);
        }
    }

    private class WhileEntry implements CallBack {
        @Override
        public void execute(VM vm) {
            if(0 != vm.datas[vm.dataPointer]) {
                vm.stack[vm.stackPointer] = vm.codePointer - 1;
                vm.stackPointer++;
            } else {
                int count = 1;
                for (vm.codePointer++; 0 != vm.codes[vm.codePointer] && 0 != count; vm.codePointer++) {
                    if (vm.codes[vm.codePointer] == '[') {
                        count++;
                    } else if (vm.codes[vm.codePointer] == ']') {
                        count--;
                    }
                }
            }
        }
    }

    private class WhileExit implements CallBack {
        @Override
        public void execute(VM vm) {
            if (0 != vm.datas[vm.dataPointer]) {
                vm.stackPointer--;
                vm.codePointer = vm.stack[vm.stackPointer];
            }
        }
    }

    private char getChar() {
        char temp;
        try {
            temp = (char) System.in.read();
        } catch (IOException e) {
            e.printStackTrace();
            temp = 0;
        }
        return temp;
    }
}

HelloWorld.java

package com.afirez.brainfuck;
/**
 * Project: brainfuck
 * Author: afirez
 * Date: 2016/7/29 0029.
 */
public class HelloWorld {
    public static void main(String[] args) {
        new Parser(() -> "++++++++++[>+++++++>++++++++++>+++>+<<<<-]" +
                ">++.>+.+++++++..+++.>++.<<+++++++++++++++." +
                ">.+++.------.--------.>+.>.").run();
    }
}

运行结果

HelloWorld.PNG