public class Scanner

public class Scanner

const char EOF = '\u0080'; // return this for end of file
const char CR = '\r';
const char LF = '\n';

static TextReader input;
static TextWriter output;
static char ch; // lookahead character (= next (unprocessed) character in input stream)
static int line, col; // line and column number of ch in input stream

/* Initializes the scanner. */
public static void Init (TextReader r) {
Init(r, Console.Out);
}

public static void Init (TextReader r, TextWriter w) {
input = r;
output = w;
line = 1; col = 0;
NextCh(); // read 1st char into ch, increment col to 1
}

/* Reads next character from input stream into ch.
* Keeps pos, line and col in sync with reading position. */
static void NextCh () {
try {
ch = (char) input.Read();
switch (ch) {
case CR:
ch = (char) input.Read(); // skip CR
line++; col = 0;
break;
case LF:
line++; col = 0; break;
case '\uffff': // read returns -1 at end of file
ch = EOF; break;
default: col++; break;
}
} catch (IOException) {
ch = EOF;
}
}

/* Returns next token.
* To be used by parser. */
public static Token Next () { // classe TOKEN
/*---------------------------------*/
/*----- insert your code here -----*/
/*---------------------------------*/
}

/* Error handling for the scanner.
* Prints error message to output. */
static void Error (string msg) {
// leave this here for scanner testing
if (output != null) output.WriteLine("-- line {0}, col {1}: {2}", line, col, msg);
else Parser.Errors.Error(msg);
}