+// (C) 2006-2007 all rights reserved; see LICENSE file for BSD-style license
+
package edu.berkeley.sbp;
-import java.io.*;
-import java.util.*;
-import java.lang.reflect.*;
-import java.lang.ref.*;
import edu.berkeley.sbp.util.*;
-import edu.berkeley.sbp.*;
-import edu.berkeley.sbp.*;
-
-/** an element which matches exactly one input token */
-public abstract class Atom<T> extends Element implements Topology<T> {
-
- protected abstract Topology<T> top();
- public abstract String toString();
-
- public Topology toAtom() { return this; }
- // Topology Thunks //////////////////////////////////////////////////////////////////////////////
+/**
+ * <font color=green>
+ * an element which matches some set of one-token-long input strings
+ * </font>.
+ *
+ * <p>
+ * This class is a topology over itself (yes, this is impredicative).
+ * This means that you can call Atom.union(Atom) and get back an Atom.
+ * If you are interested in the topology of <i>tokens</i> which this
+ * Atom can match, use the <tt>getTokenTopology()</tt> method.
+ * </p>
+ */
+public abstract class Atom<Token>
+ extends Element
+ implements Topology<Atom<Token>> {
+
+ /** the set (topology) of tokens that can match this element */
+ public abstract Topology<Token> getTokenTopology();
+
+ StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
- public Topology<T> unwrap() { return top().unwrap(); }
- public Topology<T> empty() { return top().empty(); }
- public boolean contains(T v) { return top().contains(v); }
- public Topology<T> intersect(Topology<T> t) { return top().intersect(t); }
- public Topology<T> minus(Topology<T> t) { return top().minus(t); }
- public Topology<T> union(Topology<T> t) { return top().union(t); }
- public Topology<T> complement() { return top().complement(); }
- public boolean disjoint(Topology<T> t) { return top().disjoint(t); }
- public boolean containsAll(Topology<T> t) { return top().containsAll(t); }
- public int hashCode() { return top().hashCode(); }
- public boolean equals(Object o) { return o != null && o instanceof Atom && ((Atom)o).top().equals(top()); }
-
- // Subclasses //////////////////////////////////////////////////////////////////////////////
-
- public static class Infer<T extends Token> extends Atom<T> {
- private final Element e;
- public Infer(Element e) { this.e = e; }
- public Topology<T> top() { return (Topology<T>)e.toAtom(); }
- public String toString() { return e.toString(); /* FIXME should be toAtom() */ }
- }
-
- public static class Invert<T extends Token> extends Atom<T> {
- private final Atom<T> a;
- public Invert(Atom<T> a) { this.a = a; }
- public Topology<T> top() { return ((Topology<T>)a.top()).complement(); }
- public String toString() { return "~"+a; }
- }
-
- public static class Hack<T extends Token> extends Atom<T> {
- private final Atom<T> a;
- static final Topology leftright =
- edu.berkeley.sbp.misc.CharToken.rightBrace.union(edu.berkeley.sbp.misc.CharToken.leftBrace);
- public Hack(Atom<T> a) { this.a = a; }
- public Topology<T> top() { return ((Topology<T>)a.top()).minus(leftright); }
- public String toString() { return "~"+a; }
- }
-
}
+