5 files changed, 44 insertions, 1 deletions

diff --git a/src/runtime/c/pgf/data.h b/src/runtime/c/pgf/data.h
index 9bc73dd0a..131201132 100644
--- a/src/runtime/c/pgf/data.h
+++ b/src/runtime/c/pgf/data.h
@@ -167,6 +167,7 @@ typedef enum {
 	PGF_SYMBOL_KS,
 	PGF_SYMBOL_KP,
 	PGF_SYMBOL_BIND,
+	PGF_SYMBOL_SOFT_BIND,
 	PGF_SYMBOL_NE
 } PgfSymbolTag;
 
diff --git a/src/runtime/c/pgf/linearizer.c b/src/runtime/c/pgf/linearizer.c
index 698bab939..732bce75a 100644
--- a/src/runtime/c/pgf/linearizer.c
+++ b/src/runtime/c/pgf/linearizer.c
@@ -723,7 +723,8 @@ pgf_lzr_linearize_symbols(PgfConcr* concr, PgfCncTreeApp* fapp,
 			}
 			break;
 		}
-		case PGF_SYMBOL_BIND: {
+		case PGF_SYMBOL_BIND:
+		case PGF_SYMBOL_SOFT_BIND: {
 			if ((*fnsp)->symbol_bind) {
 				(*fnsp)->symbol_bind(fnsp);
 			}
diff --git a/src/runtime/c/pgf/parser.c b/src/runtime/c/pgf/parser.c
index 46cfe5614..66d77175d 100644
--- a/src/runtime/c/pgf/parser.c
+++ b/src/runtime/c/pgf/parser.c
@@ -145,6 +145,7 @@ pgf_prev_extern_sym(PgfSymbol sym)
 	case PGF_SYMBOL_VAR:
 		return *((PgfSymbol*) (((PgfSymbolVar*) i.data)+1));
 	case PGF_SYMBOL_BIND:
+	case PGF_SYMBOL_SOFT_BIND:
 		return *((PgfSymbol*) (((PgfSymbolBIND*) i.data)+1));
 	case PGF_SYMBOL_NE:
 		return *((PgfSymbol*) (((PgfSymbolNE*) i.data)+1));
@@ -1137,6 +1138,10 @@ pgf_symbols_cmp(GuString* psent, size_t sent_len, BIND_TYPE* pbind, PgfSymbols*
 			*pbind = BIND_HARD;
 			break;
 		}
+		case PGF_SYMBOL_SOFT_BIND: {
+			*pbind = BIND_SOFT;
+			break;
+		}
 		case PGF_SYMBOL_NE: {
 			return -2;
 		}
@@ -1635,6 +1640,31 @@ pgf_parsing_symbol(PgfParsing* ps, PgfItem* item, PgfSymbol sym)
 		}
 		break;
 	}
+	case PGF_SYMBOL_SOFT_BIND: {
+		if (ps->before->start_offset == ps->before->end_offset) {
+			if (ps->before->needs_bind) {
+				PgfParseState* state =
+					pgf_new_parse_state(ps, ps->before->end_offset, BIND_HARD);
+				if (state != NULL) {
+					if (state->next == NULL) {
+						state->viterbi_prob = 
+							item->inside_prob+item->conts->outside_prob;
+					}
+
+					pgf_item_advance(item, ps->pool);
+					gu_buf_heap_push(state->agenda, pgf_item_prob_order, &item);
+				} else {
+					pgf_item_free(ps, item);
+				}
+			} else {
+				pgf_item_free(ps, item);
+			}
+		} else {
+			pgf_item_advance(item, ps->pool);
+			gu_buf_heap_push(ps->before->agenda, pgf_item_prob_order, &item);
+		}
+		break;
+	}
 	default:
 		gu_impossible();
 	}
diff --git a/src/runtime/c/pgf/printer.c b/src/runtime/c/pgf/printer.c
index 78c2b74db..8b737266e 100644
--- a/src/runtime/c/pgf/printer.c
+++ b/src/runtime/c/pgf/printer.c
@@ -280,6 +280,10 @@ pgf_print_symbol(PgfSymbol sym, GuOut *out, GuExn *err)
 		gu_puts("BIND", out, err);
 		break;
 	}
+	case PGF_SYMBOL_SOFT_BIND: {
+		gu_puts("SOFT_BIND", out, err);
+		break;
+	}
 	default:
 		gu_impossible();
 	}
diff --git a/src/runtime/c/pgf/reader.c b/src/runtime/c/pgf/reader.c
index 477adc069..c40781e26 100644
--- a/src/runtime/c/pgf/reader.c
+++ b/src/runtime/c/pgf/reader.c
@@ -723,6 +723,13 @@ pgf_read_symbol(PgfReader* rdr)
 		gu_return_on_exn(rdr->err, gu_null_variant);
 		break;
 	}
+	case PGF_SYMBOL_SOFT_BIND: {
+		gu_new_variant(PGF_SYMBOL_SOFT_BIND,
+		               PgfSymbolBIND,
+		               &sym, rdr->opool);
+		gu_return_on_exn(rdr->err, gu_null_variant);
+		break;
+	}
 	default:
 		pgf_read_tag_error(rdr);
 	}