public static void main(String[] args) {
FileReader fr = null;
StateMachine sm = new StateMachine();
ArrayList<Token> tokenList = new ArrayList();
String letters = "";
String digits = "";
String symbols = "";
boolean encounteredSentinel = false;
boolean encounteredDot = false;
boolean encounteredPlusOrMinus = false;
boolean encounteredFinalDigit = false;
// read in the name of file from command line.
if (args.length <= 0) {
// print out error and then terminate.
System.out.println("Error. Enter file at command line.");
System.exit(4);
} else {
try {
fr = new FileReader(args[0]);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
char sourceChar = ' ';
int num = 0;
while (true) {
if (encounteredSentinel) break;
try {
num = fr.read();
if (num < 0) {
// end of file reached
encounteredSentinel = true;
// send a space back down to switch statements to form last
// token.
num = ' ';
// break;
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
sourceChar = (char) num;
// System.out.println("sourceChar: " + sourceChar);
// System.exit(0);
if (sm.currentState() == 0) {
switch (sourceChar) {
// if we see space in state 0 go pull another char off stream.
case ' ':
case '\n':
case '\t':
case '\r':
break;
case ':':
sm.setState(1);
break;
case '+':
sm.setState(3);
break;
case '-':
sm.setState(4);
break;
case '*':
sm.setState(5);
break;
case '/':
sm.setState(6);
break;
case '(':
sm.setState(7);
break;
case ')':
sm.setState(8);
break;
case 'a':
case 'b':
case 'c':
case 'd':
case 'e':
case 'f':
case 'g':
case 'h':
case 'i':
case 'j':
case 'k':
case 'l':
case 'm':
case 'n':
case 'o':
case 'p':
case 'q':
case 'r':
case 's':
case 't':
case 'u':
case 'v':
case 'w':
case 'x':
case 'y':
case 'z':
case 'A':
case 'B':
case 'C':
case 'D':
case 'E':
case 'F':
case 'G':
case 'H':
case 'I':
case 'J':
case 'K':
case 'L':
case 'M':
case 'N':
case 'O':
case 'P':
case 'Q':
case 'R':
case 'S':
case 'T':
case 'U':
case 'V':
case 'W':
case 'X':
case 'Y':
case 'Z':
letters += sourceChar;
sm.setState(9);
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
digits += sourceChar;
sm.setState(11);
break;
case '^':
sm.setState(10);
break;
case '.':
if (encounteredDot) {
System.out.println("Error. Multiple dots detected.");
System.exit(4);
}
encounteredDot = true;
digits += sourceChar;
// sm.setState(11);
break;
default:
System.out.println("Error. Character is not in Calculator Language.");
System.exit(4);
} // end switch
} else if (sm.currentState() == 1) {
switch (sourceChar) {
case '=':
sm.setState(2);
// create a Token and add it to list
// Token token = new Token(":=", "assign");
// tokenList.add(token);
break;
default:
sm.setState(0); // if we didn't find an acceptable token for
// this state
System.out.println("Error in state 1.");
System.exit(4);
break;
} // end switch
} else if (sm.currentState() == 2) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
// create Token and add it to token list.
Token token = new Token(":=", "assign");
tokenList.add(token);
sm.setState(0);
break;
default:
sm.setState(0);
System.out.println("Error in state 2");
System.exit(4);
} // end switch
} else if (sm.currentState() == 3) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token("+", "plus");
tokenList.add(token);
sm.setState(0);
break;
case '+':
sm.setState(12);
break;
default:
System.out.println("Error in state 3");
System.exit(4);
}
} else if (sm.currentState() == 4) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token("-", "minus");
tokenList.add(token);
sm.setState(0);
break;
case '-':
sm.setState(13);
break;
default:
System.out.println("Error in state 4");
System.exit(4);
}
} else if (sm.currentState() == 5) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token("*", "times");
tokenList.add(token);
sm.setState(0);
break;
default:
System.out.println("Error in state 5");
System.exit(4);
}
} else if (sm.currentState() == 6) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token("/", "div");
tokenList.add(token);
sm.setState(0);
break;
case '/':
// handle single line comments.
sm.setState(17);
break;
case '*':
// handle multi-line comments.
sm.setState(18);
break;
default:
System.out.println("Error in state 6");
System.exit(4);
}
} else if (sm.currentState() == 7) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token("(", "lparen");
tokenList.add(token);
sm.setState(0);
break;
default:
System.out.println("Error in state 7");
System.exit(4);
}
} else if (sm.currentState() == 8) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token(")", "rparen");
tokenList.add(token);
sm.setState(0);
break;
default:
System.out.println("Error in state 8");
System.exit(4);
}
} else if (sm.currentState() == 9) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
if (letters.equals("read") || letters.equals("write")) {
Token token = new Token(letters, "keyword");
tokenList.add(token);
letters = "";
break;
}
Token token = new Token(letters, "id");
tokenList.add(token);
sm.setState(0);
letters = "";
break;
case 'a':
case 'b':
case 'c':
case 'd':
case 'e':
case 'f':
case 'g':
case 'h':
case 'i':
case 'j':
case 'k':
case 'l':
case 'm':
case 'n':
case 'o':
case 'p':
case 'q':
case 'r':
case 's':
case 't':
case 'u':
case 'v':
case 'w':
case 'x':
case 'y':
case 'z':
case 'A':
case 'B':
case 'C':
case 'D':
case 'E':
case 'F':
case 'G':
case 'H':
case 'I':
case 'J':
case 'K':
case 'L':
case 'M':
case 'N':
case 'O':
case 'P':
case 'Q':
case 'R':
case 'S':
case 'T':
case 'U':
case 'V':
case 'W':
case 'X':
case 'Y':
case 'Z':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
letters += sourceChar; // concatenate numbers with any
// letters seen.
break;
default:
System.out.println("Error detected in state 9.");
System.exit(4);
}
} else if (sm.currentState() == 10) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token("^", "exponent");
tokenList.add(token);
sm.setState(0);
break;
default:
System.out.println("Error. Invalid characater in State 10.");
System.exit(4);
}
} else if (sm.currentState() == 11) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token(digits, "number");
tokenList.add(token);
sm.setState(0);
digits = "";
encounteredDot = false;
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
digits += sourceChar;
break;
case '.':
if (encounteredDot) {
System.out.println("Error. Multiple dots in number.");
System.exit(4);
}
digits += sourceChar;
encounteredDot = true;
break;
case 'e':
case 'E':
sm.setState(14);
digits += sourceChar;
break;
default:
System.out.println("Error in state 11");
System.exit(4);
}
} else if (sm.currentState() == 12) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token("++", "increment");
tokenList.add(token);
sm.setState(0);
break;
default:
System.out.println("Error in state 12.");
System.exit(4);
}
} else if (sm.currentState() == 13) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token("--", "decrement");
tokenList.add(token);
sm.setState(0);
break;
default:
System.out.println("Error in state 13.");
System.exit(4);
}
} else if (sm.currentState() == 14) {
switch (sourceChar) {
case '+':
case '-':
sm.setState(15);
digits += sourceChar;
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
digits += sourceChar;
sm.setState(16);
break;
default:
System.out.println("Error. Expecting + or - or integer.");
System.exit(4);
}
} else if (sm.currentState() == 15) {
switch (sourceChar) {
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
digits += sourceChar;
sm.setState(16);
break;
default:
System.out.println("Error. Invalid character after + or - in exponent.");
System.exit(4);
}
} else if (sm.currentState() == 16) {
switch (sourceChar) {
case ' ':
case '\n':
case '\t':
case '\r':
Token token = new Token(digits, "number");
tokenList.add(token);
sm.setState(0);
digits = "";
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
digits += sourceChar;
break;
default:
System.out.println("Error. Invalid character at end of the file.");
System.out.println("sourceChar: " + sourceChar);
System.exit(4);
}
} else if (sm.currentState() == 17) {
// stay in this state unless we see newline or carriage return.
switch (sourceChar) {
case '\n':
case '\r':
sm.setState(0);
break;
}
} else if (sm.currentState() == 18) {
// stay in this state until we see a star
switch (sourceChar) {
case '*':
sm.setState(19);
break;
}
} else if (sm.currentState() == 19) {
// if we see a forward slash go to state zero
// otherwise go back to state 18.
switch (sourceChar) {
case '/':
sm.setState(0);
break;
default:
sm.setState(18);
break;
}
}
} // end while
// print out the contents of the token list.
for (int i = 0; i < tokenList.size(); i++) {
System.out.println(tokenList.get(i).toString());
}
System.exit(0);
} // end main method
