public class NaurTextProcessing {
    private final int MAXPOS = 10;
    private boolean debugOn = false;
    public void turnDebugOn(){
        debugOn = true;
    }
    public void turnDebugOff(){
        debugOn = false;
    }

    private char returnChar(RandomAccessFile inFile){         //get character()
        try{
            char characterRead;
            if(inFile.getFilePointer() == inFile.length())      //if we are at end of file return an empty character.
                characterRead = '\0';
            else                                                //if we are not at end of inFile then read in next char
                characterRead = (char)inFile.readByte();

            if(characterRead =='\n')                            //if character read is a newline then return a blank
                characterRead = ' ';
            return(characterRead);                            //Otherwise return character that was read from the file
        }catch(Exception e){
            System.out.println("**** Error in NaurApp.returnChar () ****");
            System.out.println("\t" + e);
            return '\0';
        }
    }

    public void runApp(){
        try{
            char currentChar;           //current character being processed
            int lineLength = 0;         //length of current output line
            char state = '0';           //current state of finite state machine
            StringBuffer    word = new StringBuffer();      //current word being built
            File inputFile = new File("naur.dat");
            if(!inputFile.exists()){
                System.out.println("input file 'naur.dat' does not exist.");
                return;
            }
            RandomAccessFile inFile = new RandomAccessFile(inputFile, "r"); //character.digit(state,10) returns integer value corresponding to character state
            while(Character.digit(state,10) < 4){           //Computation is performed in base-10 arithmetic.
                currentChar = returnChar(inFile);
                if(debugOn){
                    System.out.print("State: " + state + "\t");
                    switch(currentChar){                        //if switch(state)
                        case '\0':
                            System.out.println("End of file.");
                            break;
                        case ' ':
                            System.out.println("Blank/Carriage Return.");
                            break;
                        default:
                            System.out.println("Character read: " + currentChar +".");
                    }
                }
                switch(state){
                    case '0':
                        if(debugOn)
                            System.out.println("Entering state 0.");
                        switch(currentChar){
                            case ' ':       //character is a blank or a newline
                                break;              //T1 state = '4';
                            case '\0':              //end of file was reached
                                state = '4';        //this terminates loop
                                break;              //T2
                            default:                //T3
                                word.append(currentChar);
                                state = '1';
                                break;
                        }                           //switch (currentChar)
                        break;
                    case '1':
                        if(debugOn)
                            System.out.println("Entering state 1");
                        switch(currentChar){
                            case ' ':            //character is a blank or a newline
                                System.out.print(word.toString());      //T4
                                lineLength = word.length();
                                word = new StringBuffer();
                                state = '2';
                                break;
                            case '\0':      //end of file was reached
                                System.out.println(word.toString());    //T5
                                state = '4';        //this terminates loop
                                break;
                            default:
                                if(word.length() <= MAXPOS)             //T6
                                    word.append(currentChar);
                                else
                                    state = '5';        //this terminates loop
                                break;                  //T7
                        }
                    case '2':
                        if(debugOn)
                            System.out.println("Entering state 2");
                        switch(currentChar){
                            case ' ':       //character is a blank or a newline
                                break;          //T8
                            case '\0':      //end of file was reached
                                state = '4';            //this terminates loop
                                break;          //T9
                            default:            //T10
                                word.append(currentChar);
                                state = '3';
                                break;
                        }
                        break;
                    case '3':
                        if(debugOn)
                            System.out.println("Entering state 3");
                        switch(currentChar){
                            case ' ':
                            case '\0':
                                if((lineLength + word.length()) <= MAXPOS){
                                    System.out.print(currentChar);
                                    System.out.print(word.toString());
                                    lineLength = lineLength + 1 + word.length();
                                    word = new StringBuffer();
                                }
                                else{
                                    System.out.println();
                                    System.out.print(word.toString());
                                    lineLength = word.length();
                                    word = new StringBuffer();
                                }
                                if(currentChar != '\0')
                                    state = '2';        //T11
                                else
                                    state = '4';         //this terminates loop //T12
                                break;
                        }
                        break;
                }
            }
            while(Character.digit(state, 10) < 4)
                System.out.println();
            if(state == '5')
                System.out.println("Word longer than permitted length encountered");
            inFile.close();
        }catch(Exception e){
            System.out.println("**** Error in NaurApp.main() ****");
            System.out.println("\t + e");
        }
    }   //runApp()
}