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) p.queueReductions(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, fromEmptyReduction);  // ALLOC
 144             n.queueEmptyReductions();
 145             if (!fromEmptyReduction) n.queueReductions(parent);
 146             return true;
 147         }
 148
 149         public void uninhibit(int p, Sequence s) {
 150             if (s.hated!=null)
 151                 for(Sequence s2 : s.hated)
 152                     inhibited.remove(p, s2);
 153         }
 154
 155         public void inhibit(Reduction r, int p) {
 156             if (r.position.owner().hated == null) return;
 157             // remember that dead states are still allowed to shift -- just not allowed to reduce
 158             boolean reset = false;
 159             for(Sequence seq : r.position.owner().hated) {
 160                 if (performed.contains(p,seq)) {
 161                     uninhibit(p, seq);
 162                     //System.out.println("\nresetting due to " + r.position.owner() + " killing " + seq);
 163                     //inhibited.clear();
 164                     inhibited.add(p, seq);
 165                     //inhibited = new HashMapBag<Integer,Sequence>();
 166                     reset = true;
 167                     resets++;
 168                     throw new Reset();
 169                 }
 170                 inhibited.add(p, seq);
 171             }
 172         }
 173
 174         /** perform all reduction operations */
 175         public void reduce() {
 176             try {
 177                 reducing = true;
 178                 if (reducing_list==null || reducing_list.length < hash.size())
 179                     reducing_list = new Phase.Node[hash.size() * 4];
 180                 hash.toArray(reducing_list);
 181                 int num = hash.size();
 182                 for(int i=0; i<num; i++) {
 183                     Node n = reducing_list[i];
 184                     n.queueEmptyReductions();
 185                     // INVARIANT: we never "see" a node until its parent-set is complete, modulo merges
 186                 }
 187                 for(int i=0; i<num; i++) {
 188                     Node n = reducing_list[i];
 189                     reducing_list[i] = null;
 190                     n.queueReductions();
 191                 }
 192             } catch (Reset r) {
 193                 reset();
 194                 reduce();
 195             }
 196         }
 197
 198         class Reset extends RuntimeException { }
 199
 200         public void invoke(State st, Forest result, Node n) {
 201             good |= next.newNode(n, result, st, false);
 202         }
 203
 204         /** perform all shift operations, adding promoted nodes to <tt>next</tt> */
 205         public void shift(Phase next, Forest result) throws ParseFailed {
 206             // this massively improves GC performance
 207             if (prev!=null) prev.hash = null;
 208             this.next = next;
 209             closed = true;
 210             Forest res = null;
 211             boolean ok = false;
 212             for(Phase.Node n : hash.values()) {
 213                 if (token == null && n.state.isAccepting()) {
 214                     if (finalResult==null) finalResult = new Forest.Ref();
 215                     finalResult.merge(n.holder);
 216                 }
 217                 if (token == null) continue;
 218                 n.state.invokeShifts(token, this, result, n);
 219             }
 220
 221             if (!good && token!=null)
 222                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected character")+" "+ANSI.purple(token)+" encountered at "+ANSI.green(getLocation())+"\n", token, hash.values()),
 223                                         getLocation());
 224             if (token==null && finalResult==null)
 225                 throw new ParseFailed(ParseFailed.error(ANSI.red("unexpected end of file\n"), token, hash.values()),
 226                                         getLocation());
 227         }
 228
 229
 230         public class Waiting {
 231             Node parent;
 232             Forest pending;
 233             State state;
 234             boolean fromEmptyReduction;
 235             Reduction reduction;
 236             public Waiting(Node parent, Forest pending, State state, boolean fromEmptyReduction, Reduction reduction) {
 237                 waits++;
 238                 this.parent = parent;
 239                 this.pending = pending;
 240                 this.state = state;
 241                 this.fromEmptyReduction = fromEmptyReduction;
 242                 this.reduction = reduction;
 243             }
 244             public void perform() {
 245                 //System.out.println("performing: " + reduction.position);
 246                 newNode(parent, pending, state, fromEmptyReduction, reduction);
 247             }
 248         }
 249
 250         // GSS Nodes //////////////////////////////////////////////////////////////////////////////
 251
 252         /** a node in the GSS */
 253         public final class Node extends FastSet<Node> implements Invokable<Reduction, Node, Node> {
 254
 255             public boolean touched = false;
 256             private Forest.Ref holder = null;
 257             private boolean allqueued = false;
 258
 259             /** what state this node is in */
 260             public final State 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
 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 queueReductions() {
 270                 if (!reducing) return;
 271                 if (allqueued) return;
 272                 allqueued = true;
 273                 int where = parents().size();
 274                 state.invokeReductions(token, this, this, null);
 275             }
 276
 277             public void queueReductions(Node n2) {
 278                 if (!allqueued) { queueReductions(); return; }
 279                 state.invokeReductions(token, this, this, n2);
 280             }
 281
 282             public final void invoke(Reduction r, Node n, Node n2) {
 283                 if (n==null) {
 284                     if (r.position.pos==0) r.reduce(this);
 285                     return;
 286                 }
 287                 if (r.position.pos==0) return;
 288                 if (n2==null) r.reduce(n);
 289                 else          r.reduce(n, n2);
 290             }
 291             public void queueEmptyReductions() {
 292                 if (!reducing) return;
 293                 state.invokeReductions(token, this, null, null);
 294             }
 295
 296             private boolean fe;
 297             public boolean dead = false;
 298             public boolean redo = false;
 299             private Node(Node parent, Forest pending, State state, boolean fe) {
 300                 this.fe = fe;
 301                 this.state = state;
 302                 this.holder().merge(pending);
 303                 Phase start = parent==null ? null : parent.phase();
 304                 if (parent != null) parents().add(parent, true);
 305                 if (Phase.this.hash.get(state, start) != null) throw new Error("severe problem!");
 306                 Phase.this.hash.put(state, start, this);
 307             }
 308         }
 309
 310         public int toInt() { return pos+1; }
 311         public int size() { return hash==null ? 0 : hash.size(); }
 312     }
 313
 314 }