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 TreeMaker<T> ret = new TreeMaker<T>();
22 visit(ret, new Boolean(toss), null);
23 if (toss && ret.size() > 1) throw new Ambiguous(this);
27 static <T> Forest<T> singleton(Input.Location loc) { return create(loc, null, new Forest[] { }, false, true); }
28 static <T> Forest<T> singleton(Input.Location loc, Forest<T> body) { return create(loc, null, new Forest[] { body }, false, true); }
29 static <T> Forest<T> leaf(Input.Location loc, T tag) { return create(loc, tag, null, false, false); }
30 public static <T> Forest<T> create(Input.Location loc, T tag, Forest<T>[] tokens, boolean unwrap, boolean singleton) {
31 return new MyBody<T>(loc, tag, tokens, unwrap, singleton);
34 // Body //////////////////////////////////////////////////////////////////////////////
36 protected static interface Body<T> {
37 TreeMaker<T> expand(boolean toss, int i, TreeMaker<T> h);
40 protected static class MyBody<T> extends Forest<T> implements Body<T> /* extends PrintableTree<Forest<T>> implements *//*, Invokable<Tree<T>>*/ {
42 public <B,C> void visit(Invokable<Forest.Body<T>,B,C> ivbc, B b, C c) {
43 ivbc.invoke(this, b, c);
45 public <B,C> void invoke(Tree<T> 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(boolean toss, int i, TreeMaker<T> h) {
67 tokens[0].visit(h, toss, 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, toss, 0);
78 //tokens[i].visit(this,
79 for(Tree<T> r : tokens[i].expand(toss)) {
81 int old = h.toks.size();
84 while(h.toks.size() > old) h.toks.remove(h.toks.size()-1);
86 //if (!hit) throw new Error();
91 protected String headToString() { return null; }
92 protected String headToJava() { return null; }
93 protected String left() { return "{"; }
94 protected String right() { return "}"; }
95 protected boolean ignoreSingleton() { return false; }
99 // Ref //////////////////////////////////////////////////////////////////////////////
102 * This class represents a partially complete collection of
103 * forests to be viewed as a forest at some later date; once
104 * viewed, it becomes immutable
106 static class Ref<T> extends Forest<T> {
107 private FastSet<Forest<T>> hp = new FastSet<Forest<T>>();
109 public void merge(Forest p) { if (p!=this) hp.add(p, true); }
110 public <B,C> void visit(Invokable<Forest.Body<T>,B,C> ivbc, B b, C c) {
111 if (hp==null) return;
112 for(Forest<T> f : hp) f.visit(ivbc, b, c);
114 public Forest resolve() { return this; }
117 public abstract <B,C> void visit(Invokable<Forest.Body<T>,B,C> ivbc, B b, C c);
118 private static class TreeMaker<T> extends HashSet<Tree<T>> implements Invokable<Forest.Body<T>,Boolean,Integer> {
119 public ArrayList<Tree<T>> toks = new ArrayList<Tree<T>>();
120 public void invoke(Forest.Body<T> bod, Boolean toss, Integer i) {
122 ArrayList<Tree<T>> toks = this.toks;
123 this.toks = new ArrayList<Tree<T>>();
124 bod.expand(toss, 0, this);
127 bod.expand(toss, i, this);
132 // Statics //////////////////////////////////////////////////////////////////////////////
134 private static Tree[] tree_hint = new Tree[0];
135 private static final Forest[] emptyForestArray = new Forest[0];
137 protected String headToString() { return null; }
138 protected String headToJava() { return null; }
139 protected String left() { return "<?"; }
140 protected String right() { return "?>"; }
141 protected boolean ignoreSingleton() { return true; }