X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FParser.java;h=6f1098e779a418237495c20a215257123dcba860;hp=851831345cc1571c3758f5101523f325a6634fe7;hb=72cc02d0f08922a98b9f2139e814b6c33b275a43;hpb=cbae71f601dd5831cc6bf74a7407cbe067cc604a;ds=sidebyside

diff --git a/src/edu/berkeley/sbp/Parser.java b/src/edu/berkeley/sbp/Parser.java
index 8518313..6f1098e 100644
--- a/src/edu/berkeley/sbp/Parser.java
+++ b/src/edu/berkeley/sbp/Parser.java
@@ -13,9 +13,7 @@ public abstract class Parser<T extends Token, R> {
 
     private final Table pt;
 
-    /**
-     *  create a parser to parse the grammar with start symbol <tt>u</tt>
-     */
+    /** create a parser to parse the grammar with start symbol <tt>u</tt> */
     protected Parser(Union u)  { this.pt = new Table(u, top()); }
     protected Parser(Table pt) { this.pt = pt; }
 
@@ -24,7 +22,15 @@ public abstract class Parser<T extends Token, R> {
 
 
     /** parse <tt>input</tt> for a exactly one unique result, throwing <tt>Ambiguous</tt> if not unique or <tt>Failed</tt> if none */
-    public Tree<R> parse1(Token.Stream<T> input) throws IOException, Failed, Ambiguous { return parse(input).expand1(); }
+    public Tree<R> parse1(Token.Stream<T> input) throws IOException, Failed, Ambiguous {
+        Forest<R> ret = parse(input);
+        try { return ret.expand1(); }
+        catch (Ambiguous a) {
+            System.out.println("while expanding:");
+            System.out.println(ret);
+            throw a;
+        }
+    }
 
     /** parse <tt>input</tt>, using the table <tt>pt</tt> to drive the parser */
     public Forest<R> parse(Token.Stream<T> input) throws IOException, Failed {
@@ -72,9 +78,9 @@ public abstract class Parser<T extends Token, R> {
     // Table //////////////////////////////////////////////////////////////////////////////
 
     /** an SLR(1) parse table which may contain conflicts */
-    static class Table {
+    static class Table extends Walk.Cache {
 
-        public final Walk.Cache cache = new Walk.Cache();
+        public final Walk.Cache cache = this;
         
         private void walk(Element e, HashSet<Element> hs) {
             if (e==null) return;
@@ -88,16 +94,6 @@ public abstract class Parser<T extends Token, R> {
             }
         }
 
-        /*
-        public String toString() {
-            StringBuffer sb = new StringBuffer();
-            for(Element e : walk())
-                if (e instanceof Union)
-                    ((Union)e).toString(sb);
-            return sb.toString();
-        }
-        */
-
         /** the start state */
         public final State   start;
 
@@ -138,7 +134,7 @@ public abstract class Parser<T extends Token, R> {
                         Walk.Follow wf = new Walk.Follow(top.empty(), p.owner(), all_elements, cache);
                         Reduction red = new Reduction(p);
                         state.reductions.put(wf.walk(p.owner()), red);
-                        if (wf.includesEof()) state.eofReductions.add(red, true);
+                        if (wf.includesEof()) state.eofReductions.add(red);
                     }
 
                     // if the element following this position is an atom, copy the corresponding
@@ -151,14 +147,35 @@ public abstract class Parser<T extends Token, R> {
         /** a single state in the LR table and the transitions possible from it */
         public class State implements Comparable<Table.State>, Iterable<Position> {
         
-            public final      int               idx    = master_state_idx++;
+            /*
+            public boolean isResolvable(Token t) {
+                boolean found = false;
+                for(Reduction r : getReductions(t)) {
+                    Position p = r.position;
+                    if (!p.isRightNullable(cache)) continue;
+                    if (p.owner().firstp()==p) continue;
+                    if (found) {
+                        // found two items meeting criteria #1
+                        return false;
+                    } else {
+                        found = true;
+                        continue;
+                    }
+                    if (p.element()==null) continue;
+                    Topology first = new Walk.First(top(), cache).walk(p.element());
+                    if (first.contains(t))
+                }
+            }
+            */
+
+            public  final     int               idx    = master_state_idx++;
             private final     HashSet<Position> hs;
 
             private transient HashMap<Element,State>          gotoSetNonTerminals = new HashMap<Element,State>();
             private transient TopologicalBag<Token,State>     gotoSetTerminals    = new TopologicalBag<Token,State>();
 
             private           TopologicalBag<Token,Reduction> reductions          = new TopologicalBag<Token,Reduction>();
-            private           FastSet<Reduction>              eofReductions       = new FastSet<Reduction>();
+            private           HashSet<Reduction>              eofReductions       = new HashSet<Reduction>();
             private           TopologicalBag<Token,State>     shifts              = new TopologicalBag<Token,State>();
             private           boolean                         accept              = false;
 
@@ -277,7 +294,7 @@ public abstract class Parser<T extends Token, R> {
         public class Reduction {
             // FIXME: cleanup; almost everything in here could go in either Sequence.Position.getRewrite() or else in GSS.Reduct
             public final int numPop;
-            private final Position position;
+            /*private*/ final Position position;
             private final Forest[] holder;    // to avoid constant reallocation
             public int hashCode() { return position.hashCode(); }
             public boolean equals(Object o) {
@@ -301,6 +318,13 @@ public abstract class Parser<T extends Token, R> {
                 return reduce(parent, numPop-1, rex, onlychild, target);
             }
 
+            private Forest zero = null;
+            public Forest zero() {
+                if (zero != null) return zero;
+                if (numPop > 0) throw new Error();
+                return zero = position.rewrite(null);
+            }
+
             // FIXME: this could be more elegant and/or cleaner and/or somewhere else
             private Forest reduce(GSS.Phase.Node parent, int pos, Forest rex, GSS.Phase.Node onlychild, GSS.Phase target) {
                 if (pos>=0) holder[pos] = parent.pending();