src/edu/berkeley/sbp/GSS.java

   1 // Copyright 2006 all rights reserved; see LICENSE file for BSD-style license
   2
   3 package edu.berkeley.sbp;
   4 import edu.berkeley.sbp.*;
   5 import edu.berkeley.sbp.util.*;
   6 import edu.berkeley.sbp.Parser.Table.*;
   7 import edu.berkeley.sbp.Sequence.Position;
   8 import java.io.*;
   9 import java.util.*;
  10 import java.lang.reflect.*;
  11
  12 /** implements Tomita's Graph Structured Stack */
  13 class GSS {
  14
  15     static int count = 0;
  16     static int shifts = 0;
  17     static int reductions = 0;
  18     int resets = 0;
  19     int waits = 0;
  20
  21     Input input;
  22
  23     public GSS(Input input) { this.input = input; }
  24
  25     private Phase.Node[] reducing_list = null;
  26
  27     // FIXME: right now, these are the performance bottleneck
  28     HashMapBag<Sequence,Phase.Waiting> waiting         = new HashMapBag<Sequence,Phase.Waiting>();
  29     HashMapBag<Integer,Sequence>       performed       = new HashMapBag<Integer,Sequence>();
  30     HashMapBag<Integer,Sequence>       lastperformed   = new HashMapBag<Integer,Sequence>();
  31     HashMapBag<Integer,Sequence>       expected        = new HashMapBag<Integer,Sequence>();
  32
  33     /** FIXME */
  34     Forest.Many finalResult;
  35
  36     /** corresponds to a positions <i>between tokens</i> the input stream; same as Tomita's U_i's */
  37     class Phase<Tok> implements Invokable<State, Forest, Phase<Tok>.Node>, IntegerMappable, GraphViz.ToGraphViz, Iterable<Phase.Node> {
  38
  39         public Iterator<Phase.Node> iterator() { return hash.iterator(); }
  40         public void invoke(State st, Forest result, Node n) {
  41             shifts++;
  42             good |= next.newNode(n, result, st, false);
  43         }
  44
  45         /** the token immediately after this phase */
  46         final Tok token;
  47
  48         private final int pos;
  49
  50         boolean reducing;
  51         private IntPairMap<Phase.Node> hash;  /* ALLOC */
  52         private boolean closed;
  53         private boolean good;
  54         private Phase next = null;
  55         private Phase prev;
  56         private Input.Location location;
  57         private Input.Location nextLocation;
  58         private Input.Location prevLocation;
  59
  60         public final Parser parser;
  61
  62         private Forest forest;
  63
  64         public Phase(Phase prev, Parser parser, Phase previous, Tok token, Input.Location location,
  65                      Input.Location nextLocation, Forest forest) throws ParseFailed {
  66             this.prevLocation = prev==null ? location : prev.getLocation();
  67             this.prev = prev;
  68             this.forest = forest;
  69             this.parser = parser;
  70             this.pos = previous==null ? 0 : previous.pos+1;
  71             this.token = token;
  72             this.location = location;
  73             this.nextLocation = nextLocation;
  74             performed.clear();
  75             reset();
  76         }
  77
  78         public void reset() throws ParseFailed {
  79             waiting.clear();
  80             expected.clear();
  81             lastperformed.clear();
  82             lastperformed.addAll(performed);
  83             performed.clear();
  84             hash = new IntPairMap<Phase.Node>();
  85             reset = false;
  86             good = false;
  87             closed = false;
  88             reducing = false;
  89             finalResult = null;
  90             if (prev != null) prev.shift(this, forest);
  91         }
  92
  93
  94         public boolean isDone() throws ParseFailed {
  95             if (token != null) return false;
  96             if (token==null && finalResult==null)
  97                 ParseFailed.error("unexpected end of file",
  98                                   getLocation(),
  99                                   token,
 100                                   hash.values(),
 101                                   getLocation().createRegion(getLocation()),
 102                                   input,
 103                                   GSS.this);
 104             return true;
 105         }
 106
 107         public Input.Location getPrevLocation() { return prevLocation; }
 108         public Input.Location getLocation() { return location; }
 109         public Input.Region   getRegion() { return getPrevLocation().createRegion(getLocation()); }
 110         public Input.Location getNextLocation() { return nextLocation; }
 111
 112         /** add a new node (merging with existing nodes if possible)
 113          *  @param parent             the parent of the new node
 114          *  @param result             the SPPF result corresponding to the new node
 115          *  @param state              the state that the new node is in
 116          *  @param fromEmptyReduction true iff this node is being created as a result of a reduction of length zero (see GRMLR paper)
 117          *  @param start              the earliest part of the input contributing to this node (used to make merging decisions)
 118          */
 119         public boolean newNode(Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 120             Node p = hash.get(state, parent==null?null:parent.phase());
 121             if (p != null)  return newNode2(p, parent, pending, state, fromEmptyReduction);
 122             else            return newNode3(parent, pending, state, fromEmptyReduction);
 123         }
 124         public void newNode(Node parent, Forest pending, State state, boolean fromEmptyReduction, Position reduction) {
 125             int pos = parent==null?0:parent.phase()==null?0:parent.phase().pos;
 126             Sequence owner = reduction==null ? null : reduction.owner();
 127             if (reduction!=null) {
 128                 if (owner.hates!=null) {
 129                     for (Sequence s : performed.getAll(pos))
 130                         if (owner.hates.contains(s))
 131                             return;
 132                     for (Sequence s : lastperformed.getAll(pos))
 133                         if (owner.hates.contains(s)) {
 134                             //System.out.println("now expecting ["+pos+"] => " + s);
 135                             expected.add(pos, s);
 136                             return;
 137                         }
 138                 }
 139                 if (owner.needs != null)
 140                     for(Sequence s : owner.needs)
 141                         if (!performed.contains(pos, s)) {
 142                             waiting.add(s, new Waiting(parent, pending, state, fromEmptyReduction, reduction));
 143                             return;
 144                         }
 145                 if (!performed.contains(pos, owner)) {
 146                     performed.add(pos, owner);
 147                     if (owner.hated != null)
 148                         for(Sequence seq : owner.hated)
 149                             if (performed.contains(pos, seq)) {
 150                                 performed.remove(pos, seq);
 151                                 reset = true;
 152                             }
 153                 }
 154             }
 155             newNode(parent, pending, state, fromEmptyReduction);
 156             if (reduction != null) {
 157                 boolean redo = true;
 158                 while(redo) {
 159                     redo = false;
 160                     for(Waiting w : waiting.getAll(owner)) {
 161                         if (w.parent==parent || (parent!=null&&w.parent!=null&&w.parent.phase()==parent.phase())) {
 162                             waiting.remove(owner, w);
 163                             w.perform();
 164                             redo = true;
 165                             break;
 166                         }
 167                     }
 168                 }
 169             }
 170         }
 171
 172         private boolean newNode2(Node p, Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 173             if (p.merge(parent, pending)) return true;
 174             p.parents().add(parent, true);
 175             if (p!=parent && !fromEmptyReduction && reducing) p.performReductions(parent);
 176             return true;
 177         }
 178
 179         private boolean newNode3(Node parent, Forest pending, State state, boolean fromEmptyReduction) {
 180             do {
 181                 if (token != null && state.canShift(token)) break;
 182                 if (state.isAccepting()) break;
 183                 if (token==null) break;
 184                 if (!state.canReduce(token)) return false;
 185                 //if (count > 1) break;
 186                 //if (r.numPop == 0) break;
 187                 //r.reduce(pending, parent, null, Phase.this, null);
 188                 //return;
 189             } while(false);
 190
 191             Node n = new Node(parent, pending, state);  // ALLOC
 192             if (reducing) {
 193                 n.performEmptyReductions();
 194                 if (!fromEmptyReduction) n.performReductions(parent);
 195             }
 196             return true;
 197         }
 198
 199         /** perform all reduction operations */
 200         public void reduce() throws ParseFailed {
 201             try {
 202                 reducing = true;
 203                 if (reducing_list==null || reducing_list.length < hash.size())
 204                     reducing_list = new Phase.Node[hash.size() * 4];
 205                 hash.toArray(reducing_list);
 206                 int num = hash.size();
 207                 for(int i=0; i<num; i++) {
 208                     Node n = reducing_list[i];
 209                     n.performEmptyReductions();
 210                     // INVARIANT: we never "see" a node until its parent-set is complete, modulo merges
 211                 }
 212                 for(int i=0; i<num; i++) {
 213                     Node n = reducing_list[i];
 214                     reducing_list[i] = null;
 215                     n.performReductions();
 216                 }
 217                 if (reset) {
 218                     reset = false;
 219                     resets++;
 220                     throw new Reset();
 221                 }
 222                 for(int i : expected)
 223                     for(Sequence s : expected.getAll(i))
 224                         if (!performed.contains(i, s)) {
 225                             //System.out.println("resetting due to pos="+i+": " + s + " " + System.identityHashCode(s));
 226                             resets++;
 227                             throw new Reset();
 228                         }
 229             } catch (Reset r) {
 230                 reset();
 231                 reduce();
 232             }
 233             count = 0;
 234         }
 235
 236         private boolean reset = false;
 237         class Reset extends RuntimeException { }
 238
 239         /** perform all shift operations, adding promoted nodes to <tt>next</tt> */
 240         public void shift(Phase next, Forest result) throws ParseFailed {
 241             // this massively improves GC performance
 242             if (prev!=null && parser.helpgc) {
 243                 prev.hash = null;
 244             }
 245             this.next = next;
 246             closed = true;
 247             Forest res = null;
 248             boolean ok = false;
 249             for(Phase.Node n : hash.values()) {
 250                 if (token == null && n.state.isAccepting()) {
 251                     if (finalResult==null) finalResult = new Forest.Many();
 252                     for(Object f : n.results())
 253                         finalResult.merge((Forest)f);
 254                 }
 255                 if (token == null) continue;
 256                 n.state.invokeShifts(token, this, result, n);
 257             }
 258
 259             if (!good && token!=null)
 260                 ParseFailed.error("unexpected character",
 261                                   getLocation(),
 262                                   token,
 263                                   hash.values(),
 264                                   getRegion(),
 265                                   input,
 266                                   GSS.this);
 267
 268             if (token==null && finalResult==null)
 269                 ParseFailed.error("unexpected end of file",
 270                                   getLocation(),
 271                                   token,
 272                                   hash.values(),
 273                                   getLocation().createRegion(getLocation()),
 274                                   input,
 275                                   GSS.this);
 276         }
 277
 278
 279         class Waiting {
 280             Node parent;
 281             Forest pending;
 282             State state;
 283             boolean fromEmptyReduction;
 284             Position reduction;
 285             public Waiting(Node parent, Forest pending, State state, boolean fromEmptyReduction, Position reduction) {
 286                 waits++;
 287                 this.parent = parent;
 288                 this.pending = pending;
 289                 this.state = state;
 290                 this.fromEmptyReduction = fromEmptyReduction;
 291                 this.reduction = reduction;
 292             }
 293             public void perform() {
 294                 //System.out.println("performing: " + reduction.position);
 295                 newNode(parent, pending, state, fromEmptyReduction, reduction);
 296             }
 297         }
 298
 299         // Node /////////////////////////////////////////////////////////////////////////////////
 300
 301         /** a node in the GSS */
 302         final class Node implements Invokable<Position, Node, Node>, IntegerMappable, GraphViz.ToGraphViz {
 303             public FastSet<Node> set = new FastSet<Node>();
 304
 305
 306             private boolean allqueued = false;
 307
 308             /** what state this node is in */
 309             public final Parser.Table<Tok>.State<Tok> state;
 310
 311             /** which Phase this Node belongs to (node that Node is also a non-static inner class of Phase) */
 312             public  Phase phase() { return Phase.this; }
 313
 314             private HashSet<Forest.Many> resultMap = new HashSet<Forest.Many>();
 315             public Iterable<Forest.Many> results() { return resultMap; }
 316             public FastSet<Node> parents() { return set; }
 317             public boolean merge(Node parent, Forest result) {
 318                 // FIXME: inefficient!
 319                 for(Forest.Many f : results()) {
 320                     if (f.parents.contains(parent) /* UGLY: */ && f.parents.size()==1) {
 321                         f.merge(result);
 322                         return true;
 323                     }
 324                 }
 325                 Forest.Many f = new Forest.Many();
 326                 f.parents.add(parent);
 327                 f.merge(result);
 328                 resultMap.add(f);
 329                 set.add(parent, true);
 330                 return false;
 331             }
 332
 333             public void performReductions() {
 334                 if (allqueued) return;
 335                 allqueued = true;
 336                 state.invokeReductions(token, this, this, null);
 337             }
 338
 339             public void performReductions(Node n2) {
 340                 if (!allqueued) performReductions();
 341                 else            state.invokeReductions(token, this, this, n2);
 342             }
 343
 344             public void performEmptyReductions() { state.invokeReductions(token, this, null, null); }
 345             public final void invoke(Position r, Node n, Node n2) {
 346                 reductions++;
 347                 if (n==null || n2==null || r.pos==0) {
 348                     if (r.pos==0) {
 349                         if (n==null) n = this;
 350                         else return;
 351                     }
 352                     if (n==null) return;
 353                     Forest[] holder = new Forest[r.pos];
 354                     if (r.pos==0) n.finish(r, r.zero(n.phase().getLocation().createRegion(n.phase().getLocation())), n.phase());
 355                     else          n.reduce(r, r.pos-1,  n.phase(), null);
 356                 } else {
 357                     if (r.pos<=0) throw new Error("called wrong form of reduce()");
 358                     int pos = r.pos-1;
 359                     n.reduce(r, pos, n.phase(), n2);
 360                 }
 361             }
 362
 363             public void reduce(Position r, int pos, Phase target, Node only) {
 364                 Forest[] holder = r.holder;
 365                 Forest old = holder[pos];
 366
 367                 HashSet<Forest> rr = new HashSet<Forest>();
 368                 for(Forest result : results()) rr.add(result);
 369                 for(Forest result : rr)
 370                     for(Node child : ((Forest.Many<?>)result).parents) {
 371                         if (only != null && child!=only) continue;
 372                         holder[pos] = result;
 373                         if (pos==0) child.finish(r, r.rewrite(child.phase().getLocation().createRegion(target.getLocation())), target);
 374                         else        child.reduce(r, pos-1, target, null);
 375                     }
 376
 377                 holder[pos] = old;
 378             }
 379
 380             public void finish(Position r, Forest result, Phase<Tok> target) {
 381                 Parser.Table<Tok>.State<Tok> state0 = state.gotoSetNonTerminals.get(r.owner());
 382                 if (result==null) throw new Error();
 383                 if (state0!=null)
 384                     target.newNode(this, result, state0, r.pos<=0, r);
 385             }
 386
 387             private Node(Node parent, Forest pending, State state) {
 388                 this.state = state;
 389                 this.merge(parent, pending);
 390                 Phase start = parent==null ? null : parent.phase();
 391                 if (parent != null) parents().add(parent, true);
 392                 if (Phase.this.hash.get(state, start) != null) throw new Error("severe problem!");
 393                 Phase.this.hash.put(state, start, this);
 394             }
 395             public int toInt() { return idx; }
 396             private final int idx = node_idx++;
 397
 398             // GraphViz //////////////////////////////////////////////////////////////////////////////
 399
 400             public GraphViz.Node toGraphViz(GraphViz gv) {
 401                 if (gv.hasNode(this)) return gv.createNode(this);
 402                 GraphViz.Node n = gv.createNode(this);
 403                 n.label = ""+state.toStringx();
 404                 n.shape = "rectangle";
 405                 n.fill = "green";
 406                 for(Forest result : results()) n.edge(result, "");
 407                 for(Node parent : parents()) n.edge(parent, "");
 408                 ((GraphViz.Group)phase().toGraphViz(gv)).add(n);
 409                 return n;
 410             }
 411             public boolean isTransparent() { return false; }
 412             public boolean isHidden() { return false; }
 413
 414         }
 415         private int node_idx = 0;
 416
 417         public int toInt() { return pos+1; }
 418         public int size() { return hash==null ? 0 : hash.size(); }
 419
 420         // GraphViz //////////////////////////////////////////////////////////////////////////////
 421
 422         public GraphViz.Node toGraphViz(GraphViz gv) {
 423             if (gv.hasNode(this)) return gv.createNode(this);
 424             GraphViz.Group g = gv.createGroup(this);
 425             g.label = "Phase " + pos;
 426             g.color = "gray";
 427             g.cluster = true;
 428             return g;
 429         }
 430         public boolean isTransparent() { return false; }
 431         public boolean isHidden() { return false; }
 432
 433     }
 434 }