import edu.berkeley.sbp.*;
import edu.berkeley.sbp.util.*;
-/** a token of input -- note that this represents an <i>actual input token</i> rather than an <tt>Element</tt> which <i>matches</i> a token */
-public interface Input {
+/** a stream of tokens to be parsed */
+public interface Input<Token> {
- /** this is declared abstract as a way of forcing subclasses to provide a thoughtful implementation */
- public abstract String toString();
+ /** returns the token just beyond the current location and advances beyond it */
+ public Token next() throws IOException;
- /** a sequence of input tokens; returns null when EOF is reached */
- public static interface Stream<Tok> {
- public Tok next(int numstates, int resets, int waits) throws IOException;
- public abstract Location getLocation();
- }
+ /** returns the location the input stream is currently at */
+ public Location<Token> getLocation();
- /** a location *between tokens* in the input stream */
- public static interface Location {
+ /** a location <i>between tokens<i> in the input stream */
+ public static interface Location<Tok> extends Comparable<Location> {
public String toString();
}
+
+ public static class Region<Loc extends Location> /* implements Topology<Location<Tok>> */ {
+ public final Loc start;
+ public final Loc end;
+ public Region(Loc a, Loc b) {
+ switch(a.compareTo(b)) {
+ case -1:
+ case 0: start=a; end=b; return;
+ case 1: start=b; end=a; return;
+ default: throw new Error("impossible");
+ }
+ }
+ }
}