1 // Copyright 2006 all rights reserved; see LICENSE file for BSD-style license
3 package edu.berkeley.sbp;
6 import java.lang.reflect.*;
7 import java.lang.ref.*;
8 import edu.berkeley.sbp.*;
9 import edu.berkeley.sbp.util.*;
11 /** <font color=purple>a stream of <tt>Token</tt>s to be parsed</font> */
12 public interface Input<Token> {
14 /** returns the token just beyond the current location and advances beyond it */
15 public Token next() throws IOException;
17 /** returns the location the input stream is currently at */
18 public Location<Token> getLocation();
20 /** should return a short string describing where the input is coming from */
21 public String getName();
24 * <b>Optional:</b> <i>If possible</i>, this method will return a
25 * rendering of the input region (for example, if the input is a
26 * region of characters, it would be those characters) --
27 * otherwise, returns null. In any case, the string returned
28 * will be no more than <tt>maxLength</tt> characters long;
29 * typically ellipses will be inserted to perform truncation.
31 public abstract String showRegion(Region<Token> r, int maxLength);
33 /** <font color=purple>a location (position) in the input stream -- <i>between tokens</i></font> */
34 public static interface Location<Token> extends Comparable<Location> {
36 /** return the region between this location and <tt>loc</tt> */
37 public Region<Token> createRegion(Location<Token> loc);
39 public String toString();
41 /** the location following this one */
42 public Location next();
44 /** the location preceding this one */
45 public Location prev();
48 /** <font color=purple>a contiguous set of <tt>Location</tt>s</font> */
49 public static interface Region<Token> /* implements Topology<Location<Tok>> */ {
52 * the toString() method of Region should return a <80char
53 * "rendition" of the input region, if possible
55 public abstract String toString();
57 /** The location of the start of this region */
58 public abstract Location<Token> getStart();
60 /** The location of the end of this region */
61 public abstract Location<Token> getEnd();