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