1 package edu.berkeley.sbp;
2 import edu.berkeley.sbp.*;
3 import edu.berkeley.sbp.*;
4 import edu.berkeley.sbp.*;
5 import edu.berkeley.sbp.util.*;
8 import java.lang.reflect.*;
10 //////////////////////////////////////////////////////////////////////////////
13 // - fix public/package/private status
16 //////////////////////////////////////////////////////////////////////////////
17 // Optimizations to add
19 // ** NOTE: not all of these are appropriate for this class -- it is
20 // simply a list of optimizations not implemented. This
21 // class is meant to remain simple and easy to understand;
22 // optimizations which obscure that do not belong here (they
23 // should go into the compiled version instead)
25 /** implements Tomita's Graph Structured Stack */
30 /** corresponds to a positions <i>between tokens</i> the input stream; same as Tomita's U_i's */
33 /** the token immediately after this phase */
34 public final Token token;
36 /** currently this is necessary only for the code() hack -- it doesn't actually correspond to the input */
37 private final int pos;
40 public Forest.Ref finalResult = null;
42 /** all nodes, keyed by the value returned by code() */
43 private HashMap<Long,Phase.Node> hash = new HashMap<Long,Phase.Node>(); /* ALLOC */
45 /** the number of nodes in this phase */
46 private int numNodes = 0;
48 boolean closed = false;
50 private Token.Location location;
51 public Phase(Phase previous, Token token, Token.Location location) {
52 this.pos = previous==null ? 0 : previous.pos+1;
54 this.location = location;
57 public boolean isDone() { return token == null; }
59 private String error = "generic syntax error";
60 public void checkFailure() throws Parser.Failed {
62 throw new Parser.Failed(error, getLocation());
65 public Token.Location getLocation() { return location; }
67 /** add a new node (merging with existing nodes if possible)
68 * @param parent the parent of the new node
69 * @param result the SPPF result corresponding to the new node
70 * @param state the state that the new node is in
71 * @param fromEmptyReduction true iff this node is being created as a result of a reduction of length zero (see GRMLR paper)
72 * @param start the earliest part of the input contributing to this node (used to make merging decisions)
74 public void newNode(Node parent, Forest pending, Parser.Table.State state, boolean fromEmptyReduction, Phase start) {
75 Node p = hash.get(code(state, start));
76 if (p != null) newNode2(p, parent, pending, state, fromEmptyReduction, start);
77 else newNode3(parent, pending, state, fromEmptyReduction, start);
79 private void newNode2(Node p, Node parent, Forest pending, Parser.Table.State state, boolean fromEmptyReduction, Phase start) {
80 p.holder.merge(pending);
81 if (p.parents.contains(parent)) return;
82 p.parents.add(parent, true);
83 if (p!=parent && !fromEmptyReduction) p.queueReductions(parent);
85 private void newNode3(Node parent, Forest pending, Parser.Table.State state, boolean fromEmptyReduction, Phase start) {
87 if (token != null && state.canShift(token)) break;
88 if (state.isAccepting()) break;
89 if (token==null) break;
91 Parser.Table.Reduction r = null;
92 for(Parser.Table.Reduction red : token==null ? state.getEofReductions() : state.getReductions(token)) { r = red; count++; }
93 //if (count==0) return; // BEWARE! this optimization is suspected to cause really nasty heisenbugs
94 //if (count > 1) break;
95 //if (r.numPop == 0) break;
96 //r.reduce(pending, parent, null, Phase.this, null);
100 Node n = new Node(parent, pending, state, start); // ALLOC
101 n.queueEmptyReductions();
102 if (!fromEmptyReduction) n.queueReductions(parent);
106 boolean reducing = false;
107 /** perform all reduction operations */
108 public void reduce() {
110 HashSet<Phase.Node> s = new HashSet<Phase.Node>();
111 s.addAll(hash.values());
112 for(Phase.Node n : s) n.queueEmptyReductions();
113 for(Phase.Node n : s) n.queueReductions();
116 /** perform all shift operations, adding promoted nodes to <tt>next</tt> */
117 public void shift(Phase next, Forest result) {
121 for(Phase.Node n : hash.values()) {
122 if (n.holder==null) continue;
124 if (token == null && n.state.isAccepting()) {
126 if (finalResult==null) finalResult = new Forest.Ref();
127 finalResult.merge(n.holder);
129 if (!n.holder.valid()) continue;
130 if (token == null) continue;
131 for(Parser.Table.State st : n.state.getShifts(token)) {
132 if (res == null) res = result;
133 next.newNode(n, res, st, true, this);
138 if (!ok && token != null) {
139 StringBuffer error = new StringBuffer();
140 error.append("error: unable to shift token \"" + token + "\"\n");
141 //error.append(" before: " +pendingReductions+ "\n");
142 //error.append(" before: " +totalReductions+ "\n");
143 //for(Phase.Node n : hash.values()) {
144 //n.queueReductions();
145 //n.queueEmptyReductions();
147 //error.append(" after: " +pendingReductions+ "\n");
148 error.append(" candidate states:\n");
149 for(Phase.Node n : hash.values()) {
150 //for(Sequence.Position p : n.state) error.append(" " + p + "\n");
151 //error.append(" --\n");
152 for(Parser.Table.Reduction r : n.state.getReductions(token)) error.append(" " + r + "\n");
153 //error.append(" ==\n");
155 next.error = error.toString();
158 // this massively improves GC performance
163 // GSS Nodes //////////////////////////////////////////////////////////////////////////////
165 /** a node in the GSS */
166 public final class Node {
168 private Forest.Ref holder = null;
170 private HashMap<Parser.Table.Reduction,Forest> cache = null;
172 /** the set of nodes to which there is an edge starting at this node */
173 public final FastSet<Node> parents = new FastSet<Node>(); /* ALLOC */
175 /** what state this node is in */
176 public final Parser.Table.State state;
177 /** which Phase this Node belongs to (node that Node is also a non-static inner class of Phase) */
178 public final Phase phase = Phase.this;
180 public HashMap<Parser.Table.Reduction,Forest> cache() {
181 return cache==null ? (cache = new HashMap<Parser.Table.Reduction,Forest>()) : cache; }
182 public Forest.Ref holder() { return holder==null ? (holder = new Forest.Ref()) : holder; }
183 public Forest pending() { return Phase.this.closed ? holder().resolve() : holder; }
184 public FastSet<Node> parents() { return parents; }
187 public void queueReductions() {
188 if (allqueued) return;
190 FastSet<Node> h = new FastSet<Node>();
191 for(Node n : parents) h.add(n);
192 for(Node n : h) queueReductions(n);
195 private boolean allqueued = false;
196 private HashSet<Node> queued = new HashSet<Node>();
198 public void queueReductions(Node n2) {
199 if (!allqueued) { queueReductions(); return; }
200 if (queued.contains(n2)) return;
203 for(Parser.Table.Reduction r : token==null ? n.state.getEofReductions() : n.state.getReductions(token)) {
206 // The problem here is that a "reduction of length 1"
207 // performed twice with different values of n2 needs
208 // to only create a *single* new result, but must add
209 // multiple parents to the node holding that result.
210 // The current reducer doesn't differentiate between
211 // the next node of an n-pop reduction and the
212 // ultimate parent of the last pop, so we need to
213 // cache instances here as a way of avoiding
216 // currently we have this weird problem where we
217 // have to do an individual reduct for each child
218 // when the reduction length is one (ie the
219 // children wind up being children of the newly
220 // created node rather than part of the popped
222 if (r.numPop <= 0) continue;
224 Forest ret = n.cache().get(r);
225 if (ret != null) r.reduce(n, n2, n.phase, ret);
226 else n.cache().put(r, r.reduce(n, n2, n.phase, null));
228 r.reduce(n, n2, Phase.this, null);
235 public void queueEmptyReductions() {
237 for(Parser.Table.Reduction r : token==null ? state.getEofReductions() : state.getReductions(token))
239 r.reduce(this, null, this.phase, r.zero());
242 private Node(Node parent, Forest pending, Parser.Table.State state, Phase start) {
244 if (pending != null) this.holder().merge(pending);
245 if (parent != null) parents.add(parent, true);
246 if (Phase.this.hash.get(code(state, start)) != null) throw new Error("severe problem!");
247 Phase.this.hash.put(code(state, start), this);
248 Phase.this.numNodes++;
249 if (parent==null) holder().valid = true; // hack to make sure that the "base" node is always considered valid
256 private static boolean equal(Object a, Object b) {
257 if (a==null && b==null) return true;
258 if (a==null || b==null) return false;
262 /** this is something of a hack right now */
263 private static long code(Parser.Table.State state, Phase start) {
264 return (((long)state.idx) << 32) | (start==null ? 0 : start.pos);
266 public boolean yak = false;