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Class att.grappa.Lexer

java.lang.Object
   |
   +----att.grappa.Lexer

public class Lexer
extends Object
A class for doing lexical analysis of dot formatted input.

Version:
1.1, 30 Sep 1999; Copyright 1996 - 1999 by AT&T Corp.
Author:
John Mocenigo, Research @ AT&T Labs

Constructor Index

 o Lexer(Reader, PrintWriter)
Create an instance of Lexer that reads from input and sends error messages to error.

Method Index

 o advance()
Advance the scanner one character in the input stream.
 o getLocation()
Get the current location in the form "[line_number(character_offser)]".
 o init()
Initialize internal tables and read two characters of input for look-ahead purposes.
 o next_token(int)
Return one Symbol.

Constructors

 o Lexer
 public Lexer(Reader input,
              PrintWriter error) throws IllegalArgumentException
Create an instance of Lexer that reads from input and sends error messages to error.

Parameters:
input - input Reader object
error - error output Writer object
Throws: IllegalArgumentException
whenever input is null

Methods

 o init
 public void init() throws IOException
Initialize internal tables and read two characters of input for look-ahead purposes.

Throws: IOException
if advance() does
See Also:
advance
 o advance
 public void advance() throws IOException
Advance the scanner one character in the input stream. This moves next_char2 to next_char and then reads a new next_char2.

Throws: IOException
whenever a problem reading from input is encountered
 o getLocation
 public String getLocation()
Get the current location in the form "[line_number(character_offser)]".

Returns:
info about the current position in the input
 o next_token
 public Symbol next_token(int debugLevel) throws IOException
Return one Symbol. This method is the main external interface to the scanner. It consumes sufficient characters to determine the next input Symbol and returns it.

Throws: IOException
if advance() does

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