partial support for epsilon rules

src/runtime/c/pgf/data.h

@@ -211,11 +211,13 @@ struct PGF_INTERNAL_DECL PgfSymbolALLCAPIT {
 
 struct PGF_INTERNAL_DECL PgfConcrLincat;
 struct PGF_INTERNAL_DECL PgfLincatBackref;
+struct PGF_INTERNAL_DECL PgfLincatEpsilon;
 
 struct PGF_INTERNAL_DECL PgfLincatField {
     ref<PgfConcrLincat> lincat;
     ref<PgfText> name;
     ref<Vector<PgfLincatBackref>> backrefs;
+    ref<Vector<PgfLincatEpsilon>> epsilons;
 
     static void release(ref<PgfLincatField> field);
 };
@@ -257,6 +259,11 @@ struct PGF_INTERNAL_DECL PgfLincatBackref {
     size_t dot;
 };
 
+struct PGF_INTERNAL_DECL PgfLincatEpsilon {
+    ref<PgfConcrLin> lin;
+    size_t seq_index;
+};
+
 struct PGF_INTERNAL_DECL PgfConcrPrintname {
     ref<PgfText> printname;
     PgfText name;

src/runtime/c/pgf/parser.cxx

@@ -137,6 +137,19 @@ public:
         this->args[d]      = choice;
     }
 
+    ParseItem(ParseItemConts *conts, PgfLincatEpsilon *epsilon, prob_t outside_prob)
+    {
+        this->outside_prob = outside_prob;
+        this->inside_prob  = epsilon->lin->absfun->prob;
+        this->conts        = conts;
+        this->lin          = epsilon->lin;
+        this->seq_index    = epsilon->seq_index;
+        this->dot          = 0;
+
+        size_t n_args = epsilon->lin->absfun->type->hypos->len;
+        memset(this->args, 0, sizeof(Choice*)*n_args);
+    }
+
     ParseItem(ParseItem *item,
               size_t d, Choice *choice)
     {
@@ -152,20 +165,33 @@ public:
         this->args[d]      = choice;
     }
 
-    static void bu_predict(PgfLincatBackref *backref, State *state, Choice *choice)
+    static void bu_predict(ref<PgfLincatField> field, State *state, Choice *choice)
     {
-        ref<PgfSequence> seq =
-            *vector_elem(backref->lin->seqs, backref->seq_index);
-        PgfSymbol sym = seq->syms.data[backref->dot];
-        ref<PgfSymbolCat> symcat = ref<PgfSymbolCat>::untagged(sym);
+        for (size_t i = 0; i < field->backrefs->len; i++) {
+            ref<PgfLincatBackref> backref = vector_elem(field->backrefs, i);
 
-        size_t index = backref->seq_index % backref->lin->lincat->fields->len;
-        ref<PgfLincatField> field = vector_elem(backref->lin->lincat->fields, index);
-        ParseItemConts *conts = choice->conts->state->get_conts(field, 0);
+            ref<PgfSequence> seq =
+                *vector_elem(backref->lin->seqs, backref->seq_index);
+            PgfSymbol sym = seq->syms.data[backref->dot];
+            ref<PgfSymbolCat> symcat = ref<PgfSymbolCat>::untagged(sym);
 
-        size_t n_args = backref->lin->absfun->type->hypos->len;
-        state->queue.push(new(n_args) ParseItem(conts, backref,
-                                                symcat->d, choice));
+            size_t index = backref->seq_index % backref->lin->lincat->fields->len;
+            ref<PgfLincatField> up_field = vector_elem(backref->lin->lincat->fields, index);
+            ParseItemConts *conts = choice->conts->state->get_conts(up_field, 0);
+
+            size_t n_args = backref->lin->absfun->type->hypos->len;
+            state->queue.push(new(n_args) ParseItem(conts, backref,
+                                                    symcat->d, choice));
+        }
+    }
+
+    static void eps_predict(ref<PgfLincatField> field, State *state, ParseItemConts *conts, prob_t outside_prob)
+    {
+        for (size_t i = 0; i < field->epsilons->len; i++) {
+            ref<PgfLincatEpsilon> epsilon = vector_elem(field->epsilons, i);
+            size_t n_args = epsilon->lin->absfun->type->hypos->len;
+            state->queue.push(new(n_args) ParseItem(conts, epsilon, outside_prob));
+        }
     }
 
     void combine(State *state, Choice *choice)
@@ -229,10 +255,7 @@ public:
             for (ParseItem *item : conts->items) {
                 item->combine(parser->after,choice);
             }
-            for (size_t i = 0; i < conts->field->backrefs->len; i++) {
-                ref<PgfLincatBackref> backref = vector_elem(conts->field->backrefs, i);
-                bu_predict(backref,parser->after,choice);
-            }
+            bu_predict(conts->field,parser->after,choice);
         }
     }
 
@@ -254,6 +277,8 @@ public:
 
                 ParseItemConts *conts = parser->after->get_conts(field, 0);
                 conts->items.push_back(this);
+
+                eps_predict(field, parser->after, conts, inside_prob+outside_prob);
             }
         }
         default:;

src/runtime/c/pgf/pgf.cxx

@@ -1506,6 +1506,7 @@ public:
             vector_elem(db_fields, i)->lincat   = lincat;
             vector_elem(db_fields, i)->name     = name;
             vector_elem(db_fields, i)->backrefs = 0;
+            vector_elem(db_fields, i)->epsilons = 0;
         }
         lincat->fields = db_fields;
 

src/runtime/c/pgf/reader.cxx

@@ -684,6 +684,7 @@ ref<Vector<PgfLincatField>> PgfReader::read_lincat_fields(ref<PgfConcrLincat> li
         field->lincat = lincat;
         field->name = read_text();
         field->backrefs = 0;
+        field->epsilons = 0;
     }
     return fields;
 }
@@ -717,7 +718,19 @@ ref<PgfConcrLin> PgfReader::read_lin()
         ref<PgfPResult> result = *vector_elem(lin->res, seq_index / n_fields);
 
         size_t dot = 0;
-        if (dot < seq->syms.len) {
+        if (dot >= seq->syms.len) {
+            size_t index = seq_index % n_fields;
+            ref<Vector<PgfLincatEpsilon>> epsilons =
+                vector_elem(lin->lincat->fields,index)->epsilons;
+            epsilons =
+                vector_resize(epsilons, epsilons->len+1,
+                              PgfDB::get_txn_id());
+            vector_elem(lin->lincat->fields,index)->epsilons = epsilons;
+            ref<PgfLincatEpsilon> epsilon =
+                vector_elem(epsilons,epsilons->len-1);
+            epsilon->lin = lin;
+            epsilon->seq_index = seq_index;
+        } else {
             PgfSymbol sym = *vector_elem(&seq->syms,dot);
             switch (ref<PgfSymbol>::get_tag(sym)) {
             case PgfSymbolCat::tag: {