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