src/edu/berkeley/sbp/Forest.java

   1 package edu.berkeley.sbp;
   2 import edu.berkeley.sbp.*;
   3 import edu.berkeley.sbp.Sequence.Position;
   4 import edu.berkeley.sbp.util.*;
   5 import java.io.*;
   6 import java.util.*;
   7 import java.lang.reflect.*;
   8
   9 /**
  10  *   <font color=blue>
  11  *   An efficient representation of a collection of trees (Tomita's
  12  *   shared packed parse forest).
  13  *   </font>
  14  */
  15 public abstract class Forest<NodeType> implements GraphViz.ToGraphViz {
  16
  17     /** assume that this forest contains exactly one tree and return it; otherwise throw an exception */
  18     public abstract Tree<NodeType> expand1() throws Ambiguous;
  19
  20     /** expand this forest into a set of trees */
  21     public void expand(HashSet<Tree<NodeType>> ht) { expand(ht, new HashSet<Forest<NodeType>>(), null); }
  22
  23     static <NodeType> Forest<NodeType> create(Input.Region loc, NodeType head, Forest<NodeType>[] children, boolean lift) {
  24         return new One<NodeType>(loc, head, children, lift);
  25     }
  26
  27     /** create a new forest */
  28     public static <NodeType> Forest<NodeType> create(Input.Region loc, NodeType head, Forest<NodeType>[] children) {
  29         return Forest.create(loc, head, children, false); }
  30
  31     // Package-Private //////////////////////////////////////////////////////////////////////////////
  32
  33     abstract void expand(HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus);
  34     abstract void gather(HashSet<Forest<NodeType>> ignore);
  35     abstract void edges(GraphViz.Node n);
  36     boolean ambiguous() { return false; }
  37
  38
  39     // One //////////////////////////////////////////////////////////////////////////////
  40
  41     /** A "single" forest with a head and child subforests */
  42     private static class One<NodeType> extends Forest<NodeType> {
  43
  44         private final Input.Region      location;
  45         private final NodeType                head;
  46         private final Forest<NodeType>[]       children;
  47
  48         /** if true, the last child's children are considered children of this node */
  49         private final boolean           lift;
  50
  51         private One(Input.Region loc, NodeType head, Forest<NodeType>[] children, boolean lift) {
  52             this.location = loc;
  53             this.head = head;
  54             this.children = children==null ? emptyForestArray : new Forest[children.length];
  55             if (children != null) System.arraycopy(children, 0, this.children, 0, children.length);
  56             if (children != null) for(int i=0; i<children.length; i++) if (children[i]==null) throw new Error(i+"");
  57             this.lift = lift;
  58         }
  59
  60         public Tree<NodeType> expand1() throws Ambiguous {
  61             Tree<NodeType>[] ret = new Tree[children.length];
  62             for(int i=0; i<children.length; i++) ret[i] = children[i].expand1();
  63             return new Tree<NodeType>(location, head, ret, lift);
  64         }
  65
  66         void gather(HashSet<Forest<NodeType>> hf) {
  67             hf.add(this);
  68             for(Forest<NodeType> f : children) f.gather(hf);
  69         }
  70         void expand(HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus) {
  71             if (ignore.contains(this)) { ht.add(bogus); return; }
  72             expand(0, new Tree[children.length], ht, ignore, bogus);
  73         }
  74         private void expand(final int i, Tree<NodeType>[] ta, HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus) {
  75             if (i==children.length) {
  76                 ht.add(new Tree<NodeType>(location, head, ta, lift));
  77             } else {
  78                 HashSet<Tree<NodeType>> ht2 = new HashSet<Tree<NodeType>>();
  79                 children[i].expand(ht2, ignore, bogus);
  80                 for(Tree<NodeType> tc : ht2) {
  81                     ta[i] = tc;
  82                     expand(i+1, ta, ht, ignore, bogus);
  83                     ta[i] = null;
  84                 }
  85             }
  86         }
  87
  88         // GraphViz, ToInt //////////////////////////////////////////////////////////////////////////////
  89
  90         public boolean isTransparent() { return false; }
  91         public boolean isHidden() { return false; }
  92         public GraphViz.Node toGraphViz(GraphViz gv) {
  93             if (gv.hasNode(this)) return gv.createNode(this);
  94             GraphViz.Node n = gv.createNode(this);
  95             n.label = headToString()==null?"":headToString();
  96             n.directed = true;
  97             edges(n);
  98             return n;
  99         }
 100         boolean edges = false; // FIXME ??
 101         public void edges(GraphViz.Node n) {
 102             if (edges) return;
 103             edges = true;
 104             for(int i=0; i<children.length; i++) {
 105                 if (i==children.length-1 && lift && !children[i].ambiguous()) {
 106                     children[i].edges(n);
 107                 } else {
 108                     n.edge(children[i], null);
 109                 }
 110             }
 111         }
 112
 113         protected String  headToString()         { return head==null?null:head.toString(); }
 114         protected String  headToJava()           { return "null"; }
 115         protected String  left()                 { return "{"; }
 116         protected String  right()                { return "}"; }
 117         protected boolean ignoreSingleton()      { return false; }
 118     }
 119
 120
 121     // Many //////////////////////////////////////////////////////////////////////////////
 122
 123     /** An "ambiguity node"; this is immutable once it has been "looked at" */
 124     static class Many<NodeType> extends Forest<NodeType> {
 125
 126         HashSet<GSS.Phase.Node> parents = new HashSet<GSS.Phase.Node>();
 127         private FastSet<Forest<NodeType>> hp = new FastSet<Forest<NodeType>>();
 128         private boolean touched = false;
 129
 130         public Many() { }
 131
 132         public Tree<NodeType> expand1() throws Ambiguous {
 133             touched();
 134             if (hp.size() > 1) {
 135                 HashSet<Forest<NodeType>> hf0 = new HashSet<Forest<NodeType>>();
 136                 Iterator<Forest<NodeType>> ih = hp.iterator();
 137                 ih.next().gather(hf0);
 138                 for(Forest<NodeType> f : hp) {
 139                     HashSet<Forest<NodeType>> hf1 = new HashSet<Forest<NodeType>>();
 140                     f.gather(hf1);
 141                     hf0.retainAll(hf1);
 142                 }
 143                 HashSet<Tree<NodeType>> ht = new HashSet<Tree<NodeType>>();
 144                 expand(ht, hf0, new Tree(null, "*"));
 145                 throw new Ambiguous((Forest<?>)this,
 146                                     (HashSet<Tree<?>>)(Object)ht);
 147             }
 148             return hp.iterator().next().expand1();
 149         }
 150
 151         void gather(HashSet<Forest<NodeType>> ht) {
 152             touched();
 153             ht.add(this);
 154             for(Forest<NodeType> f : hp) f.gather(ht);
 155         }
 156
 157         private void touched() {
 158             if (touched) return;
 159             touched = true;
 160             /*
 161             FastSet<Forest<NodeType>> f2 = new FastSet<Forest<NodeType>>();
 162             for(Forest f : hp)
 163                 if (f instanceof Forest.One) f2.add(f);
 164                 else for(Forest ff : ((Forest.Many<NodeType>)f))
 165                     f2.add(ff);
 166             hp = f2;
 167             */
 168         }
 169         public boolean contains(Forest f) {
 170             touched();
 171             return hp.contains(f);
 172         }
 173         public void merge(Forest p) {
 174             if (touched) throw new RuntimeException("attempt to merge() on a Forest.Many that has already been examined");
 175             if (p==this) throw new RuntimeException("attempt to merge() a Forest.Many to itself!");
 176             hp.add(p, true);
 177         }
 178         boolean ambiguous() {
 179             touched();
 180             if (hp.size()==0) return false;
 181             if (hp.size()==1) return hp.iterator().next().ambiguous();
 182             return true;
 183         }
 184
 185         void expand(HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus) {
 186             touched();
 187             if (ignore.contains(this)) { ht.add(bogus); return; }
 188             for (Forest<NodeType> f : hp) f.expand(ht, ignore, bogus);
 189         }
 190
 191
 192         // GraphViz, ToInt //////////////////////////////////////////////////////////////////////////////
 193
 194         public boolean isTransparent() { return hp.size()==1; }
 195         public boolean isHidden() { return hp.size()==0; }
 196         public void edges(GraphViz.Node n) {
 197             if (hp.size()==1) { hp.iterator().next().edges(n); return; }
 198             for(Forest f : hp) f.edges(n);
 199         }
 200         public GraphViz.Node toGraphViz(GraphViz gv) {
 201             if (hp.size()==1) return hp.iterator().next().toGraphViz(gv);
 202             if (gv.hasNode(this)) return gv.createNode(this);
 203             GraphViz.Node n = gv.createNode(this);
 204             n.label = "?";
 205             n.color = "red";
 206             for(Forest f : hp) n.edge(f, null);
 207             return n;
 208         }
 209     }
 210
 211     // Statics //////////////////////////////////////////////////////////////////////////////
 212
 213     private static Tree[] tree_hint = new Tree[0];
 214     private static String[] string_hint = new String[0];
 215     private static final Forest[] emptyForestArray = new Forest[0];
 216
 217     protected String  headToString()    { return null; }
 218     protected String  headToJava()      { return "null"; }
 219     protected String  left()            { return "<?"; }
 220     protected String  right()           { return "?>"; }
 221     protected boolean ignoreSingleton() { return true; }
 222 }