abstract class Token

case object T_SEMI extends Token

case object T_LPAREN extends Token

case object T_RPAREN extends Token

case class T_ID(s: String) extends Token

case class T_OP(s: String) extends Token

case class T_NUM(n: Int) extends Token

case class T_KWD(s: String) extends Token

case class T_STR(s: String) extends Token

// Loops program

//===============

/*

start := 1000; 

x := start;

y := start;

z := start;

while 0 < x do {

 while 0 < y do {

  while 0 < z do { z := z - 1 };

  z := start;

  y := y - 1

 };     

 y := start;

 x := x - 1

}

*/

val loops =

  List(T_ID("start"), T_OP(":="), T_NUM(1000), T_SEMI, T_ID("x"), T_OP(":="), 

       T_ID("start"), T_SEMI, T_ID("y"), T_OP(":="), T_ID("start"), T_SEMI, 

       T_ID("z"), T_OP(":="), T_ID("start"), T_SEMI, T_KWD("while"), T_NUM(0), 

       T_OP("<"), T_ID("x"), T_KWD("do"), T_LPAREN, T_KWD("while"), T_NUM(0), 

       T_OP("<"), T_ID("y"), T_KWD("do"), T_LPAREN, T_KWD("while"), T_NUM(0), 

       T_OP("<"), T_ID("z"), T_KWD("do"), T_LPAREN, T_ID("z"), T_OP(":="), 

       T_ID("z"), T_OP("-"), T_NUM(1), T_RPAREN, T_SEMI, T_ID("z"), T_OP(":="),

       T_ID("start"), T_SEMI, T_ID("y"), T_OP(":="), T_ID("y"), T_OP("-"), 

       T_NUM(1), T_RPAREN, T_SEMI, T_ID("y"), T_OP(":="), T_ID("start"), 

       T_SEMI, T_ID("x"), T_OP(":="), T_ID("x"), T_OP("-"), T_NUM(1), T_RPAREN) 

// Fib program

//=============

/*

write "Fib";

read n;  

minus1 := 0;

minus2 := 1;

while n > 0 do {

       temp := minus2;

       minus2 := minus1 + minus2;

       minus1 := temp;

       n := n - 1

};

write "Result";

write minus2

*/

val fib =

  List(T_KWD("write"), T_STR("Fib"), T_SEMI, T_KWD("read"), T_ID("n"), 

       T_SEMI, T_ID("minus1"), T_OP(":="), T_NUM(0), T_SEMI, T_ID("minus2"), 

       T_OP(":="), T_NUM(1), T_SEMI, T_KWD("while"), T_ID("n"), T_OP(">"), 

       T_NUM(0), T_KWD("do"), T_LPAREN, T_ID("temp"), T_OP(":="), 

       T_ID("minus2"), T_SEMI, T_ID("minus2"), T_OP(":="), T_ID("minus1"), 

       T_OP("+"), T_ID("minus2"), T_SEMI, T_ID("minus1"), T_OP(":="), 

       T_ID("temp"), T_SEMI, T_ID("n"), T_OP(":="), T_ID("n"), T_OP("-"), 

       T_NUM(1), T_RPAREN, T_SEMI, T_KWD("write"), T_STR("Result"), T_SEMI, 

       T_KWD("write"), T_ID("minus2"))

// Factors program

//=================

/*

write "Input n please";

read n;

write "The factors of n are";

f := 2;

while n != 1 do {

    while (n / f) * f == n do {

        write f;

        n := n / f

    };

    f := f + 1

}

*/

val factors = 

  List(T_KWD("write"), T_STR("Input n please"), T_SEMI, T_KWD("read"), 

       T_ID("n"), T_SEMI, T_KWD("write"), T_STR("The factors of n are"), 

       T_SEMI, T_ID("f"), T_OP(":="), T_NUM(2), T_SEMI, T_KWD("while"), 

       T_ID("n"), T_OP("!="), T_NUM(1), T_KWD("do"), T_LPAREN, 

       T_KWD("while"), T_ID("n"), T_OP("/"), T_ID("f"), T_OP("*"), 

       T_ID("f"), T_OP("=="), T_ID("n"), T_KWD("do"), T_LPAREN, 

       T_KWD("write"), T_ID("f"), T_SEMI, T_ID("n"), T_OP(":="), 

       T_ID("n"), T_OP("/"), T_ID("f"), T_RPAREN, T_SEMI, T_ID("f"), 

       T_OP(":="), T_ID("f"), T_OP("+"), T_NUM(1), T_RPAREN)

// Primes program

//================

/*

end := 100;

n := 2;

while (n < end) do {

  f := 2;

  tmp := 0;

  while ((f < n / 2 + 1) && (tmp == 0)) do {

    if ((n / f) * f == n) then  { tmp := 1 } else { skip };

    f := f + 1

  };

  if (tmp == 0) then { write(n) } else { skip };

  n  := n + 1

}

*/

val primes =

  List(T_ID("end"), T_OP(":="), T_NUM(100), T_SEMI, T_ID("n"), T_OP(":="), 

       T_NUM(2), T_SEMI, T_KWD("while"), T_ID("n"), T_OP("<"), T_ID("end"), 

       T_KWD("do"), T_LPAREN, T_ID("f"), T_OP(":="), T_NUM(2), T_SEMI, 

       T_ID("tmp"), T_OP(":="), T_NUM(0), T_SEMI, T_KWD("while"), T_ID("f"), 

       T_OP("<"), T_ID("n"), T_OP("/"), T_NUM(2), T_OP("+"), T_NUM(1), 

       T_OP("&&"), T_ID("tmp"), T_OP("=="), T_NUM(0), T_KWD("do"), T_LPAREN, 

       T_KWD("if"), T_ID("n"), T_OP("/"), T_ID("f"), T_OP("*"), T_ID("f"), 

       T_OP("=="), T_ID("n"), T_KWD("then"), T_LPAREN, T_ID("tmp"), T_OP(":="),

       T_NUM(1), T_RPAREN, T_KWD("else"), T_LPAREN, T_KWD("skip"), T_RPAREN, 

       T_SEMI, T_ID("f"), T_OP(":="), T_ID("f"), T_OP("+"), T_NUM(1), 

       T_RPAREN, T_SEMI, T_KWD("if"), T_ID("tmp"), T_OP("=="), T_NUM(0), 

       T_KWD("then"), T_LPAREN, T_KWD("write"), T_ID("n"), T_RPAREN, 

       T_KWD("else"), T_LPAREN, T_KWD("skip"), T_RPAREN, T_SEMI, T_ID("n"), 

       T_OP(":="), T_ID("n"), T_OP("+"), T_NUM(1), T_RPAREN)