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         if (loc == null) throw new Error();
  25         return new One<NodeType>(loc, head, children, lift);
  26     }
  27
  28     /** create a new forest */
  29     public static <NodeType> Forest<NodeType> create(Input.Region loc, NodeType head, Forest<NodeType>[] children) {
  30         return Forest.create(loc, head, children, false); }
  31
  32     // Package-Private //////////////////////////////////////////////////////////////////////////////
  33
  34     abstract void expand(HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus);
  35     abstract void gather(HashSet<Forest<NodeType>> ignore);
  36     abstract void edges(GraphViz.Node n);
  37     boolean ambiguous() { return false; }
  38
  39     abstract Input.Region getRegion();
  40
  41     // One //////////////////////////////////////////////////////////////////////////////
  42
  43     /** A "single" forest with a head and child subforests */
  44     private static class One<NodeType> extends Forest<NodeType> {
  45
  46         private final Input.Region      location;
  47         private final NodeType                head;
  48         private final Forest<NodeType>[]       children;
  49
  50         /** if true, the last child's children are considered children of this node */
  51         private final boolean           lift;
  52
  53         Input.Region getRegion() { return location; }
  54
  55         private One(Input.Region loc, NodeType head, Forest<NodeType>[] children, boolean lift) {
  56             this.location = loc;
  57             this.head = head;
  58             this.children = children==null ? emptyForestArray : new Forest[children.length];
  59             if (children != null) System.arraycopy(children, 0, this.children, 0, children.length);
  60             if (children != null) for(int i=0; i<children.length; i++) if (children[i]==null) throw new Error(i+"");
  61             this.lift = lift;
  62         }
  63
  64         public Tree<NodeType> expand1() throws Ambiguous {
  65             Tree<NodeType>[] ret = new Tree[children.length];
  66             for(int i=0; i<children.length; i++) ret[i] = children[i].expand1();
  67             return new Tree<NodeType>(location, head, ret, lift);
  68         }
  69
  70         void gather(HashSet<Forest<NodeType>> hf) {
  71             hf.add(this);
  72             for(Forest<NodeType> f : children) f.gather(hf);
  73         }
  74         void expand(HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus) {
  75             if (ignore.contains(this)) { ht.add(bogus); return; }
  76             expand(0, new Tree[children.length], ht, ignore, bogus);
  77         }
  78         private void expand(final int i, Tree<NodeType>[] ta, HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus) {
  79             if (i==children.length) {
  80                 ht.add(new Tree<NodeType>(location, head, ta, lift));
  81             } else {
  82                 HashSet<Tree<NodeType>> ht2 = new HashSet<Tree<NodeType>>();
  83                 children[i].expand(ht2, ignore, bogus);
  84                 for(Tree<NodeType> tc : ht2) {
  85                     ta[i] = tc;
  86                     expand(i+1, ta, ht, ignore, bogus);
  87                     ta[i] = null;
  88                 }
  89             }
  90         }
  91
  92         // GraphViz, ToInt //////////////////////////////////////////////////////////////////////////////
  93
  94         public boolean isTransparent() { return false; }
  95         public boolean isHidden() { return false; }
  96         public GraphViz.Node toGraphViz(GraphViz gv) {
  97             if (gv.hasNode(this)) return gv.createNode(this);
  98             GraphViz.Node n = gv.createNode(this);
  99             n.label = headToString()==null?"":headToString();
 100             n.directed = true;
 101             edges(n);
 102             return n;
 103         }
 104         boolean edges = false; // FIXME ??
 105         public void edges(GraphViz.Node n) {
 106             if (edges) return;
 107             edges = true;
 108             for(int i=0; i<children.length; i++) {
 109                 if (i==children.length-1 && lift && !children[i].ambiguous()) {
 110                     children[i].edges(n);
 111                 } else {
 112                     n.edge(children[i], null);
 113                 }
 114             }
 115         }
 116
 117         protected String  headToString()         { return head==null?null:head.toString(); }
 118         protected String  headToJava()           { return "null"; }
 119         protected String  left()                 { return "{"; }
 120         protected String  right()                { return "}"; }
 121         protected boolean ignoreSingleton()      { return false; }
 122     }
 123
 124
 125     // Many //////////////////////////////////////////////////////////////////////////////
 126
 127     /** An "ambiguity node"; this is immutable once it has been "looked at" */
 128     static class Many<NodeType> extends Forest<NodeType> {
 129
 130         HashSet<GSS.Phase.Node> parents = new HashSet<GSS.Phase.Node>();
 131         private FastSet<Forest<NodeType>> hp = new FastSet<Forest<NodeType>>();
 132         private boolean touched = false;
 133
 134         public Many() { }
 135
 136         Input.Region getRegion() { return hp.iterator().next().getRegion(); } // all should be identical
 137
 138         public Tree<NodeType> expand1() throws Ambiguous {
 139             touched();
 140             if (hp.size() > 1) {
 141                 HashSet<Forest<NodeType>> hf0 = new HashSet<Forest<NodeType>>();
 142                 Iterator<Forest<NodeType>> ih = hp.iterator();
 143                 ih.next().gather(hf0);
 144                 for(Forest<NodeType> f : hp) {
 145                     HashSet<Forest<NodeType>> hf1 = new HashSet<Forest<NodeType>>();
 146                     f.gather(hf1);
 147                     hf0.retainAll(hf1);
 148                 }
 149                 HashSet<Tree<NodeType>> ht = new HashSet<Tree<NodeType>>();
 150                 expand(ht, hf0, new Tree(null, "*"));
 151                 throw new Ambiguous((Forest<?>)this,
 152                                     (HashSet<Tree<?>>)(Object)ht);
 153             }
 154             return hp.iterator().next().expand1();
 155         }
 156
 157         void gather(HashSet<Forest<NodeType>> ht) {
 158             touched();
 159             ht.add(this);
 160             for(Forest<NodeType> f : hp) f.gather(ht);
 161         }
 162
 163         private void touched() {
 164             if (touched) return;
 165             touched = true;
 166             /*
 167             FastSet<Forest<NodeType>> f2 = new FastSet<Forest<NodeType>>();
 168             for(Forest f : hp)
 169                 if (f instanceof Forest.One) f2.add(f);
 170                 else for(Forest ff : ((Forest.Many<NodeType>)f))
 171                     f2.add(ff);
 172             hp = f2;
 173             */
 174         }
 175         public boolean contains(Forest f) {
 176             touched();
 177             return hp.contains(f);
 178         }
 179         public void merge(Forest p) {
 180             if (touched) throw new RuntimeException("attempt to merge() on a Forest.Many that has already been examined");
 181             if (p==this) throw new RuntimeException("attempt to merge() a Forest.Many to itself!");
 182             hp.add(p, true);
 183         }
 184         boolean ambiguous() {
 185             touched();
 186             if (hp.size()==0) return false;
 187             if (hp.size()==1) return hp.iterator().next().ambiguous();
 188             return true;
 189         }
 190
 191         void expand(HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus) {
 192             touched();
 193             if (ignore.contains(this)) { ht.add(bogus); return; }
 194             for (Forest<NodeType> f : hp) f.expand(ht, ignore, bogus);
 195         }
 196
 197
 198         // GraphViz, ToInt //////////////////////////////////////////////////////////////////////////////
 199
 200         public boolean isTransparent() { return hp.size()==1; }
 201         public boolean isHidden() { return hp.size()==0; }
 202         public void edges(GraphViz.Node n) {
 203             if (hp.size()==1) { hp.iterator().next().edges(n); return; }
 204             for(Forest f : hp) f.edges(n);
 205         }
 206         public GraphViz.Node toGraphViz(GraphViz gv) {
 207             if (hp.size()==1) return hp.iterator().next().toGraphViz(gv);
 208             if (gv.hasNode(this)) return gv.createNode(this);
 209             GraphViz.Node n = gv.createNode(this);
 210             n.label = "?";
 211             n.color = "red";
 212             for(Forest f : hp) n.edge(f, null);
 213             return n;
 214         }
 215     }
 216
 217     // Statics //////////////////////////////////////////////////////////////////////////////
 218
 219     private static Tree[] tree_hint = new Tree[0];
 220     private static String[] string_hint = new String[0];
 221     private static final Forest[] emptyForestArray = new Forest[0];
 222
 223     protected String  headToString()    { return null; }
 224     protected String  headToJava()      { return "null"; }
 225     protected String  left()            { return "<?"; }
 226     protected String  right()           { return "?>"; }
 227     protected boolean ignoreSingleton() { return true; }
 228 }