1 package edu.berkeley.sbp;
2 import edu.berkeley.sbp.*;
3 import edu.berkeley.sbp.*;
4 import edu.berkeley.sbp.util.*;
7 import java.lang.reflect.*;
9 /** an efficient representation of a collection of trees (Tomita's shared packed parse forest) */
10 public abstract class Forest<T> /*extends PrintableTree<Forest.MyBody<T>>*/ implements Visitable<Forest.Body<T>> {
12 /** assume that this forest contains exactly one tree and return it; otherwise throw an exception */
13 public final Tree<T> expand1() throws Ambiguous, ParseFailed {
14 Iterator<Tree<T>> it = expand(true).iterator();
15 if (!it.hasNext()) throw new ParseFailed();
19 /** expand this forest into a set of trees */
20 public HashSet<Tree<T>> expand(boolean toss) {
21 final HashSet<Tree<T>> hs = new HashSet<Tree<T>>();
22 TreeMaker<T> ret = new TreeMaker<T>(toss) {
23 public void add(Tree<T> t) { hs.add(t); }
25 visit(ret, null, null);
26 if (toss && hs.size() > 1) throw new Ambiguous(this);
30 static <T> Forest<T> singleton(Input.Location loc) { return create(loc, null, new Forest[] { }, false, true); }
31 static <T> Forest<T> singleton(Input.Location loc, Forest<T> body) { return create(loc, null, new Forest[] { body }, false, true); }
32 static <T> Forest<T> leaf(Input.Location loc, T tag) { return create(loc, tag, null, false, false); }
33 public static <T> Forest<T> create(Input.Location loc, T tag, Forest<T>[] tokens, boolean unwrap, boolean singleton) {
34 return new MyBody<T>(loc, tag, tokens, unwrap, singleton);
37 // Body //////////////////////////////////////////////////////////////////////////////
39 protected static interface Body<T> {
40 TreeMaker<T> expand(int i, TreeMaker<T> h);
43 protected static class MyBody<T> extends Forest<T> implements Body<T> /* extends PrintableTree<Forest<T>> implements */, Invokable<Tree<T>, TreeMaker<T>, Integer> {
45 public <B,C> void visit(Invokable<Forest.Body<T>,B,C> ivbc, B b, C c) {
46 ivbc.invoke(this, b, c);
49 private final Input.Location location;
51 private final Forest<T>[] tokens;
52 private final boolean unwrap;
53 private final boolean singleton;
55 private MyBody(Input.Location loc, T tag, Forest<T>[] tokens, boolean unwrap, boolean singleton) {
58 this.tokens = tokens==null ? emptyForestArray : new Forest[tokens.length];
59 if (tokens != null) System.arraycopy(tokens, 0, this.tokens, 0, tokens.length);
60 if (tokens != null) for(int i=0; i<tokens.length; i++) if (tokens[i]==null) throw new Error(i+"");
62 this.singleton = singleton;
65 public TreeMaker<T> expand(final int i, final TreeMaker<T> h) {
67 tokens[0].visit(h, null, i);
69 } else if (i==tokens.length) {
70 h.add(new Tree<T>(null, tag, h.toks.toArray(tree_hint)));
72 } else if (unwrap && i==tokens.length-1) {
73 if (tokens[i] != null)
74 tokens[i].visit(h, null, 0);
77 tokens[i].visit(new TreeMaker<T>(h.toss) {
78 public void add(Tree<T> r) {
79 int old = h.toks.size();
82 while(h.toks.size() > old) h.toks.remove(h.toks.size()-1);
88 public void invoke(Tree<T> r, TreeMaker<T> h, Integer i) {
90 int old = h.toks.size();
93 while(h.toks.size() > old) h.toks.remove(h.toks.size()-1);
94 //ivbc.invoke(this, b, c);
97 protected String headToString() { return null; }
98 protected String headToJava() { return null; }
99 protected String left() { return "{"; }
100 protected String right() { return "}"; }
101 protected boolean ignoreSingleton() { return false; }
105 // Ref //////////////////////////////////////////////////////////////////////////////
108 * This class represents a partially complete collection of
109 * forests to be viewed as a forest at some later date; once
110 * viewed, it becomes immutable
112 static class Ref<T> extends Forest<T> {
113 private FastSet<Forest<T>> hp = new FastSet<Forest<T>>();
115 public void merge(Forest p) { if (p!=this) hp.add(p, true); }
116 public <B,C> void visit(Invokable<Forest.Body<T>,B,C> ivbc, B b, C c) {
117 if (hp==null) return;
118 for(Forest<T> f : hp)
121 public Forest resolve() { return this; }
124 public abstract <B,C> void visit(Invokable<Forest.Body<T>,B,C> ivbc, B b, C c);
125 private static abstract class TreeMaker<T> implements Invokable<Forest.Body<T>,Boolean,Integer> {
126 public ArrayList<Tree<T>> toks = new ArrayList<Tree<T>>();
127 private boolean toss;
128 public TreeMaker(boolean toss) { this.toss = toss; }
129 public abstract void add(Tree<T> t);
130 public void invoke(Forest.Body<T> bod, Boolean o, Integer i) {
132 ArrayList<Tree<T>> toks = this.toks;
133 this.toks = new ArrayList<Tree<T>>();
142 // Statics //////////////////////////////////////////////////////////////////////////////
144 private static Tree[] tree_hint = new Tree[0];
145 private static final Forest[] emptyForestArray = new Forest[0];
147 protected String headToString() { return null; }
148 protected String headToJava() { return null; }
149 protected String left() { return "<?"; }
150 protected String right() { return "?>"; }
151 protected boolean ignoreSingleton() { return true; }