CMSC 330 Project

DOWNLOAD
CMSC 330
Project 1

// Netbeans under Windows 8
import java.io.*;
// Tnis class provides the lexical analyzer for project 1
class Lexer
{
private static final int KEYWORDS = 11;
private StreamTokenizer tokenizer;
private String punctuation = ",:;.()";
private Token punctuationTokens =
{
Token.COMMA, Token.COLON, Token.SEMICOLON, Token.PERIOD,
Token.LEFT_PAREN, Token.RIGHT_PAREN
};
// Constructor that creates a lexical analyzer object given the source file
public Lexer(String fileName) throws FileNotFoundException
{
tokenizer = new StreamTokenizer(new FileReader(fileName));
tokenizer.ordinaryChar('.');
tokenizer.quoteChar('"');
}
// Returns the next token in the input stream
public Token getNextToken() throws SyntaxError, IOException
{
int token = tokenizer.nextToken();
switch (token)
{
case StreamTokenizer.TT_NUMBER:
return Token.NUMBER;
case StreamTokenizer.TT_WORD:
for (Token aToken : Token.values())
{
if (aToken.ordinal() == KEYWORDS)
break;
if (aToken.name().equals(tokenizer.sval.toUpperCase()))
return aToken;
}
throw new SyntaxError(lineNo(), "Invalid token " + getLexeme());
case StreamTokenizer.TT_EOF:
return Token.EOF;
case '"':
return Token.STRING;
default:
for (int i = 0; i < punctuation.length(); i++)
if (token == punctuation.charAt(i))
return punctuationTokens[i];
}
return Token.EOF;
}
// Returns the lexeme associated with the current token
public String getLexeme()

{

return tokenizer.sval;

}
// Returns the numeric value of the current token for numeric tokens
public double getValue()
{
return tokenizer.nval;
}
// Returns the currebt line of the input file

}

public int lineNo()
{
return tokenizer.lineno();
}