public class Token

public class Token

// token codes
public const int
//error token
NONE = 0,
//terminal classes
IDENT = 1, NUMBER = 2, CHARCONST = 3,
//+ - * / %
PLUS = 4, MINUS = 5, TIMES = 6, SLASH = 7, REM = 8,
//relational operators (must be consecutive numbers, see Parser.Relop)
//== >= > <= < !=
EQ = 9, GE = 10, GT = 11, LE = 12, LT = 13, NE = 14,
//&& ||
AND = 15, OR = 16,
//= ++ --
ASSIGN = 17, PPLUS = 18, MMINUS = 19,
//; , .
SEMICOLON = 20, COMMA = 21, PERIOD = 22,
//( ) [ ] { }
LPAR = 23, RPAR = 24, LBRACK = 25, RBRACK = 26, LBRACE = 27, RBRACE = 28,
//KEYWORDS
BREAK = 29, CLASS = 30, CONST = 31, ELSE = 32, IF = 33, NEW = 34,
READ = 35, RETURN = 36, VOID = 37, WHILE = 38, WRITE = 39,
//end of file
EOF = 40;

/* List of printable names for all kinds of tokens (e.g. for error messages).
* The token codes must index correctly into this array! */
public static readonly string[] names = {
"?",
"identifier", "number", "character constant",
"+", "-", "*", "/", "%",
"==", ">=", ">", "<=", "<", "!=",
"&&", "||",
"=", "++", "--",
";", ",", ".",
"(", ")", "[", "]", "{", "}",
"break", "class", "const", "else", "if", "new",
"read", "return", "void", "while", "write",
"end of file"
};

public int kind; // token code (NONE, IDENT, ...)
public int line; // token line number (for error messages)
public int col; // token column number (for error messages)
public int val; // numerical value (for numbers and character constants)
public string str; // string representation of token (for numbers and identifiers)
/* We keep the string representation of numbers for error messages in case the
* number literal in the source code is too big to fit into an int.
*/

public Token ( int line, int col) : this(NONE, line, col, 0, null) {}
public Token (int kind, int line, int col) : this(kind, line, col, 0, null) {}
public Token (int kind, int line, int col, int val) : this(kind, line, col, val, null) {}
public Token (int kind, int line, int col, string str) : this(kind, line, col, 0, str) {}
public Token (int kind, int line, int col, int val, string str) {
this.kind = kind;
this.line = line; this.col = col;
this.val = val; this.str = str;
}

public override bool Equals (object o) {
if (this == o) return true; // same object
Token t = o as Token;
if (t == null) return false; // not a token
return Equals(t);
}

public bool Equals (Token t) {
if (kind != t.kind || line != t.line || col != t.col) return false;
switch (kind) {
case IDENT: return str == t.str;
case NUMBER: return val == t.val && str == t.str;
case CHARCONST: return val == t.val;
}
return true;
}

/* Returns a string representation of this Token object.
* Always includes all attributes of the token in the string.
* When string or val are irrelevant, they are put in parenthesis.
*/
public override string ToString () {
StringBuilder sb = new StringBuilder();
sb.AppendFormat("line {0}, col {1}: {2}", line, col, names[kind]);
switch (kind) {
case IDENT: sb.AppendFormat(" = {0}", str); break;
case NUMBER: sb.AppendFormat(" = {0} (\"{1}\")", val, str); break;
case CHARCONST: sb.AppendFormat(" = '{0}'", (char) val); break;
}
return sb.ToString();
}
}