src/edu/berkeley/sbp/GSS.java

   1 package edu.berkeley.sbp;
   2 import edu.berkeley.sbp.*;
   3 import edu.berkeley.sbp.util.*;
   4 import edu.berkeley.sbp.Parser.Table.*;
   5 import edu.berkeley.sbp.Sequence.Position;
   6 import java.io.*;
   7 import java.util.*;
   8 import java.lang.reflect.*;
   9
  10 /** implements Tomita's Graph Structured Stack */
  11 class GSS {
  12
  13     public GSS() { }
  14
  15     private Phase.Node[] reducing_list = null;
  16     public int resets = 0;
  17     public int waits = 0;
  18
  19     HashMapBag<Integer,Sequence>       inhibited = new HashMapBag<Integer,Sequence>();
  20     HashMapBag<Sequence,Phase.Waiting> waiting   = new HashMapBag<Sequence,Phase.Waiting>();
  21     HashMapBag<Integer,Sequence>       performed = new HashMapBag<Integer,Sequence>();
  22
  23     /** FIXME */
  24     public  Forest.Ref finalResult;
  25
  26     /** corresponds to a positions <i>between tokens</i> the input stream; same as Tomita's U_i's */
  27     public class Phase<Tok> implements Invokable<State, Forest, Phase<Tok>.Node>, IntegerMappable {
  28
  29         public void invoke(State st, Forest result, Node n) {
  30             good |= next.newNode(n, result, st, false);
  31         }
  32
  33         /** the token immediately after this phase */
  34         final Tok token;
  35
  36         private final int pos;
  37
  38         boolean reducing;
  39         private IntPairMap<Phase.Node> hash;  /* ALLOC */
  40         private boolean closed;
  41         private boolean good;
  42         private Phase next = null;
  43         private Phase prev;
  44         private Token.Location location;
  45         public final Parser parser;
  46
  47         private Forest forest;
  48
  49         public Phase(Phase prev, Parser parser, Phase previous, Tok token, Token.Location location, Forest forest) {
  50             this.prev = prev;
  51             this.forest = forest;
  52             this.parser = parser;
  53             this.pos = previous==null ? 0 : previous.pos+1;
  54             this.token = token;
  55             this.location = location;
  56             inhibited.clear();
  57             reset();
  58         }
  59
  60         public void reset() {
  61             waiting.clear();
  62             performed.clear();
  63             hash = new IntPairMap<Phase.Node>();
  64             good = false;
  65             closed = false;
  66             reducing = false;
  67             finalResult = null;
  68             if (prev != null) prev.shift(this, forest);
  69         }
  70
  71
  72         public boolean isDone() throws ParseFailed {
  73             if (token != null) return false;
  74             if (token==null && finalResult==null)
  75                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected end of file\n"), token, hash.values()), getLocation());
  76             return true;
  77         }
  78
  79         public Token.Location getLocation() { return location; }
  80
  81         /** add a new node (merging with existing nodes if possible)
  82          *  @param parent             the parent of the new node
  83          *  @param result             the SPPF result corresponding to the new node
  84          *  @param state              the state that the new node is in
  85          *  @param fromEmptyReduction true iff this node is being created as a result of a reduction of length zero (see GRMLR paper)
  86          *  @param start              the earliest part of the input contributing to this node (used to make merging decisions)
  87          */
  88         public boolean newNode(Node parent, Forest pending, State state, boolean fromEmptyReduction) {
  89             Node p = hash.get(state, parent==null?null:parent.phase());
  90             if (p != null)  return newNode2(p, parent, pending, state, fromEmptyReduction);
  91             else            return newNode3(parent, pending, state, fromEmptyReduction);
  92         }
  93         public void newNode(Node parent, Forest pending, State state, boolean fromEmptyReduction, Position reduction) {
  94             int pos = parent==null?0:parent.phase()==null?0:parent.phase().pos;
  95             Sequence owner = reduction==null ? null : reduction.owner();
  96             if (reduction!=null) {
  97                 if (inhibited.contains(pos, owner)) return;
  98                 if (owner.needs != null)
  99                     for(Sequence s : owner.needs)
 100                         if (!performed.contains(pos, s)) {
 101                             waiting.add(s, new Waiting(parent, pending, state, fromEmptyReduction, reduction));
 102                             return;
 103                         }
 104                 if ((owner.needed != null && owner.needed.size()>0) ||
 105                     (owner.hated != null && owner.hated.size()>0) ||
 106                     (owner.hates != null && owner.hates.size()>0))
 107                     performed.add(pos, owner);
 108             }
 109             if (!owner.lame)
 110                 newNode(parent, pending, state, fromEmptyReduction);
 111             if (reduction!=null) inhibit(reduction, parent==null?0:parent.phase().pos);
 112             if (reduction != null) {
 113                 boolean redo = true;
 114                 while(redo) {
 115                     redo = false;
 116                     for(Waiting w : waiting.getAll(owner)) {
 117                         if (w.parent==parent || (parent!=null&&w.parent!=null&&w.parent.phase()==parent.phase())) {
 118                             waiting.remove(owner, w);
 119                             w.perform();
 120                             redo = true;
 121                             break;
 122                         }
 123                     }
 124                 }
 125             }
 126         }
 127         private boolean newNode2(Node p, Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 128             p.holder.merge(pending);
 129             if (p.parents().contains(parent)) return true;
 130             p.parents().add(parent, true);
 131             if (p!=parent && !fromEmptyReduction && reducing) p.performReductions(parent);
 132             return true;
 133         }
 134         private boolean newNode3(Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 135             do {
 136                 if (token != null && state.canShift(token)) break;
 137                 if (state.isAccepting()) break;
 138                 if (token==null) break;
 139                 if (!state.canReduce(token)) return false;
 140                 //if (count > 1) break;
 141                 //if (r.numPop == 0) break;
 142                 //r.reduce(pending, parent, null, Phase.this, null);
 143                 //return;
 144             } while(false);
 145
 146             Node n = new Node(parent, pending, state);  // ALLOC
 147             if (reducing) {
 148                 n.performEmptyReductions();
 149                 if (!fromEmptyReduction) n.performReductions(parent);
 150             }
 151             return true;
 152         }
 153
 154         public void uninhibit(int p, Sequence s) {
 155             if (s.hated!=null)
 156                 for(Sequence s2 : s.hated)
 157                     inhibited.remove(p, s2);
 158         }
 159
 160         public void inhibit(Position r, int p) {
 161             if (r.owner().hated == null) return;
 162             // remember that dead states are still allowed to shift -- just not allowed to reduce
 163             boolean reset = false;
 164             for(Sequence seq : r.owner().hated) {
 165                 if (performed.contains(p,seq)) {
 166                     uninhibit(p, seq);
 167                     //System.out.println("\nresetting due to " + r.owner() + " killing " + seq);
 168                     //inhibited.clear();
 169                     inhibited.add(p, seq);
 170                     //inhibited = new HashMapBag<Integer,Sequence>();
 171                     reset = true;
 172                     resets++;
 173                     throw new Reset();
 174                 }
 175                 inhibited.add(p, seq);
 176             }
 177         }
 178
 179         /** perform all reduction operations */
 180         public void reduce() {
 181             try {
 182                 reducing = true;
 183                 if (reducing_list==null || reducing_list.length < hash.size())
 184                     reducing_list = new Phase.Node[hash.size() * 4];
 185                 hash.toArray(reducing_list);
 186                 int num = hash.size();
 187                 for(int i=0; i<num; i++) {
 188                     Node n = reducing_list[i];
 189                     n.performEmptyReductions();
 190                     // INVARIANT: we never "see" a node until its parent-set is complete, modulo merges
 191                 }
 192                 for(int i=0; i<num; i++) {
 193                     Node n = reducing_list[i];
 194                     reducing_list[i] = null;
 195                     n.performReductions();
 196                 }
 197             } catch (Reset r) {
 198                 reset();
 199                 reduce();
 200             }
 201         }
 202
 203         class Reset extends RuntimeException { }
 204
 205         /** perform all shift operations, adding promoted nodes to <tt>next</tt> */
 206         public void shift(Phase next, Forest result) throws ParseFailed {
 207             // this massively improves GC performance
 208             if (prev!=null) prev.hash = null;
 209             this.next = next;
 210             closed = true;
 211             Forest res = null;
 212             boolean ok = false;
 213             for(Phase.Node n : hash.values()) {
 214                 if (token == null && n.state.isAccepting()) {
 215                     if (finalResult==null) finalResult = new Forest.Ref();
 216                     finalResult.merge(n.holder);
 217                 }
 218                 if (token == null) continue;
 219                 n.state.invokeShifts(token, this, result, n);
 220             }
 221
 222             if (!good && token!=null)
 223                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected character")+" "+ANSI.purple(token)+" encountered at "+ANSI.green(getLocation())+"\n", token, hash.values()),
 224                                         getLocation());
 225             if (token==null && finalResult==null)
 226                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected end of file\n"), token, hash.values()),
 227                                         getLocation());
 228         }
 229
 230
 231         public class Waiting {
 232             Node parent;
 233             Forest pending;
 234             State state;
 235             boolean fromEmptyReduction;
 236             Position reduction;
 237             public Waiting(Node parent, Forest pending, State state, boolean fromEmptyReduction, Position reduction) {
 238                 waits++;
 239                 this.parent = parent;
 240                 this.pending = pending;
 241                 this.state = state;
 242                 this.fromEmptyReduction = fromEmptyReduction;
 243                 this.reduction = reduction;
 244             }
 245             public void perform() {
 246                 //System.out.println("performing: " + reduction.position);
 247                 newNode(parent, pending, state, fromEmptyReduction, reduction);
 248             }
 249         }
 250
 251         // Node /////////////////////////////////////////////////////////////////////////////////
 252
 253         /** a node in the GSS */
 254         public final class Node extends FastSet<Node> implements Invokable<Position, Node, Node> {
 255
 256             private Forest.Ref holder = null;
 257             private boolean allqueued = false;
 258
 259             /** what state this node is in */
 260             public final Parser.Table<Tok>.State<Tok> state;
 261
 262             /** which Phase this Node belongs to (node that Node is also a non-static inner class of Phase) */
 263             public  Phase phase() { return Phase.this; }
 264             public  Forest.Ref holder() { return holder==null ? (holder = new Forest.Ref()) : holder; }
 265             public  Forest pending() { return Phase.this.closed ? holder().resolve() : holder; }
 266             public  FastSet<Node> parents() { return this; }
 267
 268             public void performReductions() {
 269                 if (allqueued) return;
 270                 allqueued = true;
 271                 state.invokeReductions(token, this, this, null);
 272             }
 273
 274             public void performReductions(Node n2) {
 275                 if (!allqueued) performReductions();
 276                 else            state.invokeReductions(token, this, this, n2);
 277             }
 278
 279             public final void invoke(Position r, Node n, Node n2) {
 280                 if (n==null || n2==null || r.pos==0) {
 281                     if (r.pos==0) {
 282                         if (n==null) n = this;
 283                         else return;
 284                     }
 285                     if (n==null) return;
 286                     Forest[] holder = new Forest[r.pos];
 287                     if (r.pos==0) n.finish(r, r.zero(), n.phase(), holder);
 288                     else                   n.reduce(r, r.pos-1, n.phase(), holder);
 289                 } else {
 290                     Forest[] holder = new Forest[r.pos];
 291                     if (r.pos<=0) throw new Error("called wrong form of reduce()");
 292                     int pos = r.pos-1;
 293                     Forest old = holder[pos];
 294                     holder[pos] = n.pending();
 295                     if (pos==0) {
 296                         System.arraycopy(holder, 0, r.holder, 0, holder.length);
 297                         Forest rex = r.rewrite(n.phase().getLocation());
 298                         n2.finish(r, rex, n.phase(), holder);
 299                     } else {
 300                         n2.reduce(r, pos-1, n.phase(), holder);
 301                     }
 302                     holder[pos] = old;
 303                 }
 304             }
 305
 306             public void reduce(Position r, int pos, Phase target, Forest[] holder) {
 307                 Forest old = holder[pos];
 308                 holder[pos] = this.pending();
 309                 if (pos==0) {
 310                     System.arraycopy(holder, 0, r.holder, 0, holder.length);
 311                     for(int i=0; i<r.pos; i++) if (r.holder[i]==null) throw new Error("realbad");
 312                     Forest rex = r.rewrite(target.getLocation());
 313                     for(Node child : this.parents()) child.finish(r, rex, target, holder);
 314                 } else {
 315                     for(Node child : this.parents()) child.reduce(r, pos-1, target, holder);
 316                 }
 317                 holder[pos] = old;
 318             }
 319
 320             public void finish(Position r, Forest result, Phase<Tok> target, Forest[] holder) {
 321                 Parser.Table<Tok>.State<Tok> state0 = state.gotoSetNonTerminals.get(r.owner());
 322                 if (result==null) throw new Error();
 323                 if (state0!=null)
 324                     target.newNode(this, result, state0, r.pos<=0, r);
 325             }
 326
 327             public void performEmptyReductions() { state.invokeReductions(token, this, null, null); }
 328
 329             private Node(Node parent, Forest pending, State state) {
 330                 this.state = state;
 331                 this.holder().merge(pending);
 332                 Phase start = parent==null ? null : parent.phase();
 333                 if (parent != null) parents().add(parent, true);
 334                 if (Phase.this.hash.get(state, start) != null) throw new Error("severe problem!");
 335                 Phase.this.hash.put(state, start, this);
 336             }
 337         }
 338
 339         public int toInt() { return pos+1; }
 340         public int size() { return hash==null ? 0 : hash.size(); }
 341     }
 342
 343 }