now fully functional Java API for custom literals

14 files changed, 399 insertions, 110 deletions

diff --git a/src/runtime/c/pgf/data.h b/src/runtime/c/pgf/data.h
index 6b1dd1780..d75b17f85 100644
--- a/src/runtime/c/pgf/data.h
+++ b/src/runtime/c/pgf/data.h
@@ -108,7 +108,7 @@ struct PgfPGF {
 	PgfFlags* gflags;
 	PgfAbstr abstract;
 	PgfCIdMap* concretes; // |-> PgfConcr*
-	GuPool* pool;
+	GuPool* pool;         // the pool in which the grammar is allocated
 };
 
 typedef struct {
@@ -203,12 +203,6 @@ typedef struct {
 typedef struct {
 } PgfSymbolBIND;
 
-typedef struct {
-	PgfExprProb* (*match)(PgfConcr* concr, PgfSymbol* psym, size_t lin_idx,
-	                      GuString sentence, size_t* poffset,
-	                      GuPool *pool, GuPool *out_pool);
-} PgfLiteralCallback;
-
 typedef GuBuf PgfProductionIdx;
 
 typedef struct {
diff --git a/src/runtime/c/pgf/literals.c b/src/runtime/c/pgf/literals.c
index 89ddfdaf2..6b47aaf31 100644
--- a/src/runtime/c/pgf/literals.c
+++ b/src/runtime/c/pgf/literals.c
@@ -12,9 +12,10 @@ GU_DEFINE_TYPE(PgfCallbacksMap, GuMap,
 
 
 static PgfExprProb*
-pgf_match_string_lit(PgfConcr* concr, PgfSymbol* psym, size_t lin_idx,
+pgf_match_string_lit(PgfLiteralCallback* self,
+                     size_t lin_idx,
                      GuString sentence, size_t* poffset,
-                     GuPool *pool, GuPool *out_pool)
+                     GuPool *out_pool)
 {
 	gu_assert(lin_idx == 0);
 
@@ -40,7 +41,6 @@ pgf_match_string_lit(PgfConcr* concr, PgfSymbol* psym, size_t lin_idx,
 		memcpy(lit_str->val, sentence+*poffset, len);
 		lit_str->val[len] = 0;
 
-		pgf_add_extern_tok(psym, lit_str->val, pool);
 		*poffset = offset;
 		return ep;
 	} else {
@@ -54,9 +54,10 @@ static PgfLiteralCallback pgf_string_literal_callback =
 
 
 static PgfExprProb*
-pgf_match_int_lit(PgfConcr* concr, PgfSymbol* psym, size_t lin_idx,
+pgf_match_int_lit(PgfLiteralCallback* self,
+                  size_t lin_idx,
                   GuString sentence, size_t* poffset,
-                  GuPool *pool, GuPool *out_pool)
+                  GuPool *out_pool)
 {
 	gu_assert(lin_idx == 0);
 
@@ -66,28 +67,32 @@ pgf_match_int_lit(PgfConcr* concr, PgfSymbol* psym, size_t lin_idx,
 
 	size_t len = offset - *poffset;
 	if (len > 0) {
-		PgfToken tok = gu_malloc(pool, len+1);
+		GuPool* tmp_pool = gu_local_pool();
+		PgfToken tok = gu_malloc(tmp_pool, len+1);
 		memcpy((char*) tok, sentence+*poffset, len);
 		((char*) tok)[len] = 0;
 
 		int val;
-		if (!gu_string_to_int(tok, &val))
+		if (!gu_string_to_int(tok, &val)) {
+			gu_pool_free(tmp_pool);
 			return NULL;
+		}
+		
+		gu_pool_free(tmp_pool);
 
-		PgfExprProb* ep = gu_new(PgfExprProb, pool);
+		PgfExprProb* ep = gu_new(PgfExprProb, out_pool);
 		ep->prob = 0;
 
 		PgfExprLit *expr_lit =
 			gu_new_variant(PGF_EXPR_LIT,
 						   PgfExprLit,
-						   &ep->expr, pool);
+						   &ep->expr, out_pool);
 		PgfLiteralInt *lit_int =
 			gu_new_variant(PGF_LITERAL_INT,
 						   PgfLiteralInt,
-						   &expr_lit->lit, pool);
+						   &expr_lit->lit, out_pool);
 		lit_int->val = val;
 
-		pgf_add_extern_tok(psym, tok, pool);
 		*poffset = offset;
 		return ep;
 	} else {
@@ -101,9 +106,10 @@ static PgfLiteralCallback pgf_int_literal_callback =
 
 
 static PgfExprProb*
-pgf_match_float_lit(PgfConcr* concr, PgfSymbol* psym, size_t lin_idx,
+pgf_match_float_lit(PgfLiteralCallback* self,
+                    size_t lin_idx,
                     GuString sentence, size_t* poffset,
-                    GuPool *pool, GuPool *out_pool)
+                    GuPool *out_pool)
 {
 	gu_assert(lin_idx == 0);
 
@@ -113,28 +119,32 @@ pgf_match_float_lit(PgfConcr* concr, PgfSymbol* psym, size_t lin_idx,
 
 	size_t len = offset - *poffset;
 	if (len > 0) {
-		PgfToken tok = gu_malloc(pool, len+1);
+		GuPool* tmp_pool = gu_local_pool();
+		PgfToken tok = gu_malloc(tmp_pool, len+1);
 		memcpy((char*) tok, sentence+*poffset, len);
 		((char*) tok)[len] = 0;
 
 		double val;
-		if (!gu_string_to_double(tok, &val))
+		if (!gu_string_to_double(tok, &val)) {
+			gu_pool_free(tmp_pool);
 			return NULL;
+		}
+		
+		gu_pool_free(tmp_pool);
 
-		PgfExprProb* ep = gu_new(PgfExprProb, pool);
+		PgfExprProb* ep = gu_new(PgfExprProb, out_pool);
 		ep->prob = 0;
 
 		PgfExprLit *expr_lit =
 			gu_new_variant(PGF_EXPR_LIT,
 						   PgfExprLit,
-						   &ep->expr, pool);
+						   &ep->expr, out_pool);
 		PgfLiteralFlt *lit_flt =
 			gu_new_variant(PGF_LITERAL_FLT,
 						   PgfLiteralFlt,
-						   &expr_lit->lit, pool);
+						   &expr_lit->lit, out_pool);
 		lit_flt->val = val;
 
-		pgf_add_extern_tok(psym, tok, pool);
 		*poffset = offset;
 		return ep;
 	} else {
@@ -148,13 +158,14 @@ static PgfLiteralCallback pgf_float_literal_callback =
 
 
 static PgfExprProb*
-pgf_match_name_lit(PgfConcr* concr, PgfSymbol* psym, size_t lin_idx,
-                    GuString sentence, size_t* poffset,
-                    GuPool *pool, GuPool *out_pool)
+pgf_match_name_lit(PgfLiteralCallback* self,
+                   size_t lin_idx,
+                   GuString sentence, size_t* poffset,
+                   GuPool *out_pool)
 {
 	gu_assert(lin_idx == 0);
 
-	GuPool* tmp_pool = gu_new_pool();
+	GuPool* tmp_pool = gu_local_pool();
 	GuStringBuf *sbuf = gu_string_buf(tmp_pool);
 	GuOut* out = gu_string_buf_out(sbuf);
 	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
@@ -168,12 +179,10 @@ pgf_match_name_lit(PgfConcr* concr, PgfSymbol* psym, size_t lin_idx,
 			len++;
 		}
 
-		PgfToken tok = gu_malloc(pool, len+1);
+		PgfToken tok = gu_malloc(tmp_pool, len+1);
 		memcpy((char*) tok, sentence+offset, len);
 		((char*) tok)[len] = 0;
 
-		pgf_add_extern_tok(psym, tok, pool);
-
 		if (i > 0)
 		  gu_putc(' ', out, err);
 		gu_string_write(tok, out, err);
@@ -189,30 +198,30 @@ pgf_match_name_lit(PgfConcr* concr, PgfSymbol* psym, size_t lin_idx,
 
 	PgfExprProb* ep = NULL;
 	if (i > 0) {
-		ep = gu_new(PgfExprProb, pool);
+		ep = gu_new(PgfExprProb, out_pool);
 		ep->prob = 0;
 
 		PgfExprApp *expr_app =
 			gu_new_variant(PGF_EXPR_APP,
 			               PgfExprApp,
-			               &ep->expr, pool);
+			               &ep->expr, out_pool);
 		GuString con = "MkSymb";
 		PgfExprFun *expr_fun =
 			gu_new_flex_variant(PGF_EXPR_FUN,
 			                    PgfExprFun,
 			                    fun, strlen(con)+1,
-			                    &expr_app->fun, pool);
+			                    &expr_app->fun, out_pool);
 		strcpy(expr_fun->fun, con);
 		PgfExprLit *expr_lit =
 			gu_new_variant(PGF_EXPR_LIT,
 			               PgfExprLit,
-			               &expr_app->arg, pool);
+			               &expr_app->arg, out_pool);
 		GuString val = gu_string_buf_freeze(sbuf, tmp_pool);
 		PgfLiteralStr *lit_str =
 			gu_new_flex_variant(PGF_LITERAL_STR,
 			                    PgfLiteralStr,
 			                    val, strlen(val)+1,
-			                    &expr_lit->lit, pool);
+			                    &expr_lit->lit, out_pool);
         strcpy(lit_str->val, val);
 	}
 
diff --git a/src/runtime/c/pgf/parser.c b/src/runtime/c/pgf/parser.c
index ee2d13415..f944bc88d 100644
--- a/src/runtime/c/pgf/parser.c
+++ b/src/runtime/c/pgf/parser.c
@@ -155,7 +155,7 @@ pgf_prev_extern_sym(PgfSymbol sym)
 	}
 }
 
-void
+static void
 pgf_add_extern_tok(PgfSymbol* psym, PgfToken tok, GuPool* pool) {
 	PgfSymbol new_sym;
 	size_t tok_len = strlen(tok);
@@ -169,7 +169,7 @@ pgf_add_extern_tok(PgfSymbol* psym, PgfToken tok, GuPool* pool) {
 	*psym = new_sym;
 }
 
-void
+static void
 pgf_add_extern_cat(PgfSymbol* psym, int d, int r, GuPool* pool) {
 	PgfSymbol new_sym;
 	PgfSymbolCat* scat = (PgfSymbolCat*)
@@ -183,6 +183,32 @@ pgf_add_extern_cat(PgfSymbol* psym, int d, int r, GuPool* pool) {
 	*psym = new_sym;
 }
 
+PgfSymbol
+pgf_collect_extern_tok(PgfParsing* ps, size_t start, size_t end)
+{
+	PgfSymbol sym = gu_null_variant;
+
+	size_t offset = start;
+	while (offset < end) {
+		size_t len = 0;
+		while (!gu_is_space(ps->sentence[offset+len])) {
+			len++;
+		}
+
+		PgfToken tok = gu_malloc(ps->pool, len+1);
+		memcpy((char*) tok, ps->sentence+offset, len);
+		((char*) tok)[len] = 0;
+
+		pgf_add_extern_tok(&sym, tok, ps->pool);
+
+		offset  += len;
+		while (gu_is_space(ps->sentence[offset]))
+			offset++;
+	}
+
+	return sym;
+}
+
 static size_t
 pgf_item_symbols_length(PgfItem* item)
 {
@@ -1581,13 +1607,13 @@ pgf_parsing_symbol(PgfParsing* ps, PgfItem* item, PgfSymbol sym)
 							   PgfLiteralCallback*);
 
 				if (callback != NULL) {
-					size_t offset = ps->before->end_offset;
-					PgfSymbol curr_sym = gu_null_variant;
+					size_t start  = ps->before->end_offset;
+					size_t offset = start;
 					PgfExprProb *ep =
-						callback->match(ps->concr, &curr_sym,
+						callback->match(callback,
 						                slit->r,
 				                        ps->sentence, &offset,
-				                        ps->pool, ps->out_pool);
+				                        ps->out_pool);
 
 					if (ep != NULL) {
 						PgfProduction prod;
@@ -1602,7 +1628,7 @@ pgf_parsing_symbol(PgfParsing* ps, PgfItem* item, PgfSymbol sym)
 							pgf_new_parse_state(ps, offset, BIND_NONE);
 						PgfItem* item =
 							pgf_new_item(ps, conts, prod);
-						item->curr_sym = curr_sym;
+						item->curr_sym = pgf_collect_extern_tok(ps,start,offset);
 						item->sym_idx  = pgf_item_symbols_length(item);
 						gu_buf_heap_push(state->agenda, pgf_item_prob_order, &item);
 					}
@@ -2506,19 +2532,6 @@ pgf_complete(PgfConcr* concr, PgfCId cat, GuString sentence,
 	return pgf_parsing_completions(ps, prefix);
 }
 
-void
-pgf_parser_add_literal(PgfConcr *concr, PgfCId cat,
-                       PgfLiteralCallback* callback)
-{
-	PgfCncCat* cnccat =
-		gu_map_get(concr->cnccats, cat, PgfCncCat*);
-	if (cnccat == NULL)
-		return;
-
-	gu_map_put(concr->callbacks, cnccat,
-	           PgfLiteralCallback*, callback);
-}
-
 static void
 pgf_morpho_iter(PgfProductionIdx* idx,
                 PgfMorphoCallback* callback,
diff --git a/src/runtime/c/pgf/parser.h b/src/runtime/c/pgf/parser.h
index 93addbf7f..afe443042 100644
--- a/src/runtime/c/pgf/parser.h
+++ b/src/runtime/c/pgf/parser.h
@@ -5,14 +5,4 @@
 #include <pgf/data.h>
 #include <pgf/expr.h>
 
-void
-pgf_add_extern_tok(PgfSymbol* psym, PgfToken tok, GuPool* pool);
-
-void
-pgf_add_extern_cat(PgfSymbol* psym, int d, int r, GuPool* pool);
-
-void
-pgf_parser_add_literal(PgfConcr *concr, PgfCId cat,
-                       PgfLiteralCallback* callback);
-
 #endif // PGF_PARSER_H_
diff --git a/src/runtime/c/pgf/pgf.c b/src/runtime/c/pgf/pgf.c
index 155b93135..ee736616c 100644
--- a/src/runtime/c/pgf/pgf.c
+++ b/src/runtime/c/pgf/pgf.c
@@ -166,3 +166,35 @@ pgf_has_linearization(PgfConcr* concr, PgfCId id)
 		gu_map_get(concr->fun_indices, id, PgfCncOverloadMap*);
 	return (overl_table != NULL);
 }
+
+GuPool*
+pgf_concr_get_pool(PgfConcr* concr)
+{
+	GuPool* pool = concr->pool;
+	if (pool == NULL)
+		pool = gu_container(concr->abstr, PgfPGF, abstract)->pool;
+	return pool;
+}
+
+void
+pgf_concr_add_literal(PgfConcr *concr, PgfCId cat,
+                      PgfLiteralCallback* callback,
+                      GuExn* err)
+{
+	if (concr->cnccats == NULL ||
+	    concr->callbacks == NULL) {
+		GuExnData* err_data = gu_raise(err, PgfExn);
+		if (err_data) {
+			err_data->data = "The concrete syntax is not loaded";
+			return;
+		}
+	}
+
+	PgfCncCat* cnccat =
+		gu_map_get(concr->cnccats, cat, PgfCncCat*);
+	if (cnccat == NULL)
+		return;
+
+	gu_map_put(concr->callbacks, cnccat,
+	           PgfLiteralCallback*, callback);
+}
diff --git a/src/runtime/c/pgf/pgf.h b/src/runtime/c/pgf/pgf.h
index 87ca3ae28..d8c364b56 100644
--- a/src/runtime/c/pgf/pgf.h
+++ b/src/runtime/c/pgf/pgf.h
@@ -151,6 +151,23 @@ GuEnum*
 pgf_complete(PgfConcr* concr, PgfCId cat, GuString string, 
              GuString prefix, GuExn* err, GuPool* pool);
 
+GuPool*
+pgf_concr_get_pool(PgfConcr* concr);
+
+typedef struct PgfLiteralCallback PgfLiteralCallback;
+
+struct PgfLiteralCallback {
+	PgfExprProb* (*match)(PgfLiteralCallback* self,
+	                      size_t lin_idx,
+	                      GuString sentence, size_t* poffset,
+	                      GuPool *out_pool);
+};
+
+void
+pgf_concr_add_literal(PgfConcr *concr, PgfCId cat,
+                      PgfLiteralCallback* callback,
+                      GuExn* err);
+
 /// @}
 
 void
diff --git a/src/runtime/c/pgf/reader.c b/src/runtime/c/pgf/reader.c
index 2dd1e73b3..afbd42242 100644
--- a/src/runtime/c/pgf/reader.c
+++ b/src/runtime/c/pgf/reader.c
@@ -1243,8 +1243,6 @@ pgf_read_concrete(PgfReader* rdr, PgfAbstr* abstr, bool with_content)
 	}
 	gu_return_on_exn(rdr->err, NULL);
 
-	pgf_parser_add_literal(concr, "Symb", &pgf_nerc_literal_callback);
-
 	return concr;
 }
 
@@ -1283,7 +1281,7 @@ pgf_concrete_load(PgfConcr* concr, GuIn* in, GuExn* err)
 	if (gu_exn_is_raised(rdr->err)) 
 		goto end;
 
-end:	
+end:
 	gu_pool_free(tmp_pool);
 }
 
@@ -1338,6 +1336,8 @@ pgf_read_pgf(PgfReader* rdr) {
 		gu_variant_is_null(gu_map_get(pgf->gflags, "split", PgfLiteral));
 	pgf->concretes = pgf_read_concretes(rdr, &pgf->abstract, with_content);
 	gu_return_on_exn(rdr->err, NULL);
+	
+	pgf->pool = rdr->opool;
 
 	return pgf;
 }
diff --git a/src/runtime/c/utils/pgf-translate.c b/src/runtime/c/utils/pgf-translate.c
index 79420cf49..fbc6e553e 100644
--- a/src/runtime/c/utils/pgf-translate.c
+++ b/src/runtime/c/utils/pgf-translate.c
@@ -88,8 +88,8 @@ int main(int argc, char* argv[]) {
 	}
 	
 	// Register a callback for the literal category Symbol
-	pgf_parser_add_literal(from_concr, "Symb",
-	                       &pgf_nerc_literal_callback);
+	pgf_concr_add_literal(from_concr, "Symb",
+	                      &pgf_nerc_literal_callback, err);
 
 	// Create an output stream for stdout
 	GuOut* out = gu_file_out(stdout, pool);
diff --git a/src/runtime/java/jpgf.c b/src/runtime/java/jpgf.c
index 2a92aa0c6..7de1d9516 100644
--- a/src/runtime/java/jpgf.c
+++ b/src/runtime/java/jpgf.c
@@ -75,6 +75,14 @@ throw_string_exception(JNIEnv *env, const char* class_name, const char* msg)
 	throw_jstring_exception(env, class_name, jmsg);
 }
 
+static JavaVM* cachedJVM;
+
+JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved)
+{
+    cachedJVM = jvm;
+    return JNI_VERSION_1_1;
+}
+
 JNIEXPORT jobject JNICALL 
 Java_org_grammaticalframework_pgf_PGF_readPGF__Ljava_lang_String_2(JNIEnv *env, jclass cls, jstring s)
 { 
@@ -645,15 +653,135 @@ JNIEXPORT jboolean JNICALL
 Java_org_grammaticalframework_pgf_Concr_hasLinearization(JNIEnv* env, jobject self, jstring jid)
 {
 	PgfConcr* concr = get_ref(env, self);
-	GuPool* tmp_pool = gu_new_pool();
+	GuPool* tmp_pool = gu_local_pool();
 	PgfCId id = j2gu_string(env, jid, tmp_pool);
 	bool res = pgf_has_linearization(concr, id);
 	gu_pool_free(tmp_pool);
 	return res;
 }
 
+typedef struct {
+	PgfLiteralCallback callback;
+	jobject jcallback;
+	jmethodID match_methodId;
+	GuFinalizer fin;
+} JPgfLiteralCallback;
+
+static PgfExprProb* 
+jpgf_literal_callback_fn(PgfLiteralCallback* self,
+                         size_t lin_idx,
+                         GuString sentence, size_t* poffset,
+                         GuPool *out_pool)
+{
+	JPgfLiteralCallback* callback = gu_container(self, JPgfLiteralCallback, callback);
+
+	JNIEnv *env;
+    (*cachedJVM)->AttachCurrentThread(cachedJVM, (void **)&env, NULL);
+
+	jstring jsentence = gu2j_string(env, sentence);
+	jobject result = (*env)->CallObjectMethod(env, callback->jcallback, callback->match_methodId, lin_idx, jsentence, *poffset);
+	
+	jclass result_class = (*env)->GetObjectClass(env, result);
+	
+	jfieldID epId = (*env)->GetFieldID(env, result_class, "ep", "Lorg/grammaticalframework/pgf/ExprProb;");
+	jobject jep = (*env)->GetObjectField(env, result, epId);
+	jclass ep_class = (*env)->GetObjectClass(env, jep);
+	jfieldID exprId = (*env)->GetFieldID(env, ep_class, "expr", "Lorg/grammaticalframework/pgf/Expr;");
+	jobject jexpr = (*env)->GetObjectField(env, jep, exprId);
+	jfieldID probId = (*env)->GetFieldID(env, ep_class, "prob", "D");
+	double prob = (*env)->GetDoubleField(env, jep, probId);
+
+	jfieldID offsetId = (*env)->GetFieldID(env, result_class, "offset", "I");
+	*poffset = (*env)->GetIntField(env, result, offsetId);
+	
+	PgfExprProb* ep = gu_new(PgfExprProb, out_pool);
+	ep->expr = gu_variant_from_ptr(get_ref(env, jexpr));
+	ep->prob = prob;
+
+	
+	{
+		// This is an uggly hack. We first show the expression ep->expr
+		// and then we read it back but in out_pool. The whole purpose
+		// of this is to copy the expression from the temporary pool
+		// that was created in the Java binding to the parser pool.
+		// There should be a real copying function or even better
+		// there must be a way to avoid copying at all.
+
+		GuPool* tmp_pool = gu_local_pool();
+
+		GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+		GuStringBuf* sbuf = gu_string_buf(tmp_pool);
+		GuOut* out = gu_string_buf_out(sbuf);
+
+		pgf_print_expr(ep->expr, NULL, 0, out, err);
+
+		GuString str = gu_string_buf_freeze(sbuf, tmp_pool);
+		GuIn* in = gu_data_in((uint8_t*) str, strlen(str), tmp_pool);
+
+		ep->expr = pgf_read_expr(in, out_pool, err);
+		if (!gu_ok(err) || gu_variant_is_null(ep->expr)) {
+			throw_string_exception(env, "org/grammaticalframework/pgf/PGFError", "The expression cannot be parsed");
+			gu_pool_free(tmp_pool);
+			return NULL;
+		}
+
+		gu_pool_free(tmp_pool);
+	}
+
+	return ep;
+}
+
+static void 
+jpgf_literal_callback_fin(GuFinalizer* self)
+{
+	JPgfLiteralCallback* callback = gu_container(self, JPgfLiteralCallback, fin);
+	
+	JNIEnv *env;
+    (*cachedJVM)->AttachCurrentThread(cachedJVM, (void **)&env, NULL);
+
+	(*env)->DeleteGlobalRef(env, callback->jcallback);
+}
+
 JNIEXPORT void JNICALL 
-Java_org_grammaticalframework_pgf_Pool_free(JNIEnv* env, jobject self, jlong ref)
+Java_org_grammaticalframework_pgf_Concr_addLiteral(JNIEnv* env, jobject self, jstring jcat, jobject jcallback)
+{
+	PgfConcr* concr = get_ref(env, self);
+	GuPool* pool = pgf_concr_get_pool(concr);
+	
+	JPgfLiteralCallback* callback = gu_new(JPgfLiteralCallback, pool);
+	callback->callback.match = jpgf_literal_callback_fn;
+	callback->jcallback = (*env)->NewGlobalRef(env, jcallback);
+	callback->fin.fn = jpgf_literal_callback_fin;
+
+	jclass callback_class = (*env)->GetObjectClass(env, jcallback);
+	callback->match_methodId = (*env)->GetMethodID(env, callback_class, "match", "(ILjava/lang/String;I)Lorg/grammaticalframework/pgf/LiteralCallback$CallbackResult;");
+
+	gu_pool_finally(pool, &callback->fin);
+	
+	GuPool* tmp_pool = gu_local_pool();
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+	pgf_concr_add_literal(concr, j2gu_string(env, jcat, tmp_pool), &callback->callback, err);
+
+	if (!gu_ok(err)) {
+		if (gu_exn_caught(err) == gu_type(PgfExn)) {
+			GuString msg = (GuString) gu_exn_caught_data(err);
+			throw_string_exception(env, "org/grammaticalframework/pgf/PGFError", msg);
+		} else {
+			throw_string_exception(env, "org/grammaticalframework/pgf/PGFError", "The literal cannot be added");
+		}
+	}
+
+	gu_pool_free(tmp_pool);
+}
+
+JNIEXPORT jlong JNICALL
+Java_org_grammaticalframework_pgf_Pool_alloc(JNIEnv* env, jclass clazz)
+{
+	return p2l(gu_new_pool());
+}
+
+JNIEXPORT void JNICALL 
+Java_org_grammaticalframework_pgf_Pool_free(JNIEnv* env, jclass clazz, jlong ref)
 {
 	gu_pool_free((GuPool*) l2p(ref));
 }
@@ -700,10 +828,64 @@ Java_org_grammaticalframework_pgf_Expr_readExpr(JNIEnv* env, jclass clazz, jstri
 	jmethodID pool_constrId = (*env)->GetMethodID(env, pool_class, "<init>", "(J)V");
 	jobject jpool = (*env)->NewObject(env, pool_class, pool_constrId, p2l(pool));
 
-	jmethodID constrId = (*env)->GetMethodID(env, clazz, "<init>", "(Lorg/grammaticalframework/pgf/Pool;Lorg/grammaticalframework/pgf/PGF;J)V");
+	jmethodID constrId = (*env)->GetMethodID(env, clazz, "<init>", "(Lorg/grammaticalframework/pgf/Pool;Ljava/lang/Object;J)V");
 	return (*env)->NewObject(env, clazz, constrId, jpool, NULL, p2l(gu_variant_to_ptr(e)));
 }
 
+JNIEXPORT jlong JNICALL 
+Java_org_grammaticalframework_pgf_Expr_initStringLit(JNIEnv* env, jclass clazz, jstring jstr, jlong jpool)
+{
+	GuPool* pool = l2p(jpool);
+	PgfExpr expr;
+
+	PgfExprLit* e =
+		gu_new_variant(PGF_EXPR_LIT,
+					   PgfExprLit,
+					   &expr, pool);
+
+	GuString str = (*env)->GetStringUTFChars(env, jstr, 0);
+	PgfLiteralStr* slit =
+		gu_new_flex_variant(PGF_LITERAL_STR,
+		                    PgfLiteralStr,
+		                    val, strlen(str)+1,
+		                    &e->lit, pool);
+	strcpy(slit->val, str);
+	(*env)->ReleaseStringUTFChars(env, jstr, str);
+
+	return expr;
+}
+
+JNIEXPORT jlong JNICALL 
+Java_org_grammaticalframework_pgf_Expr_initApp(JNIEnv* env, jclass clazz, jstring jfun, jobjectArray args, jlong jpool)
+{
+	GuPool* pool = l2p(jpool);
+	PgfExpr expr;
+
+	GuString fun = (*env)->GetStringUTFChars(env, jfun, 0);
+	PgfExprFun* e =
+		gu_new_flex_variant(PGF_EXPR_FUN,
+					        PgfExprFun,
+					        fun, strlen(fun)+1,
+					        &expr, pool);
+	strcpy(e->fun, fun);
+	(*env)->ReleaseStringUTFChars(env, jfun, fun);
+
+	size_t n_args = (*env)->GetArrayLength(env, args);
+	for (size_t i = 0; i < n_args; i++) {
+		PgfExpr fun = expr;
+		PgfExpr arg = gu_variant_from_ptr(get_ref(env, (*env)->GetObjectArrayElement(env, args, i)));
+
+		PgfExprApp* e =
+			gu_new_variant(PGF_EXPR_APP,
+						   PgfExprApp,
+						   &expr, pool);
+		e->fun = fun;
+		e->arg = arg;
+	}
+
+	return expr;
+}
+
 JNIEXPORT jstring JNICALL
 Java_org_grammaticalframework_pgf_Type_getCategory(JNIEnv* env, jobject self)
 {
diff --git a/src/runtime/java/org/grammaticalframework/pgf/Expr.java b/src/runtime/java/org/grammaticalframework/pgf/Expr.java
index ca94d0cf7..753055ff9 100644
--- a/src/runtime/java/org/grammaticalframework/pgf/Expr.java
+++ b/src/runtime/java/org/grammaticalframework/pgf/Expr.java
@@ -4,18 +4,31 @@ import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
+import java.util.Arrays;
 
 public class Expr implements Serializable {
 		private static final long serialVersionUID = 1148602474802492674L;
 	
 		private Pool pool;
-		private PGF  gr;
+		private Object master;
 		private long ref;
 
-		Expr(Pool pool, PGF gr, long ref) {
-			this.pool = pool;
-			this.gr   = gr;
-			this.ref  = ref;
+		Expr(Pool pool, Object master, long ref) {
+			this.pool   = pool;
+			this.master = master;
+			this.ref    = ref;
+		}
+
+		public Expr(String s) {
+			this.pool   = new Pool();
+			this.master = null;
+			this.ref    = initStringLit(s, pool.ref);  
+		}
+
+		public Expr(String fun, Expr... args) {
+			this.pool   = new Pool();
+			this.master = Arrays.copyOf(args, args.length);
+			this.ref    = initApp(fun, args, pool.ref);
 		}
 
 		public String toString() {
@@ -25,15 +38,18 @@ public class Expr implements Serializable {
 		public static native Expr readExpr(String s) throws PGFError;
 
 		private static native String showExpr(long ref);
-		
+
+		private static native long initStringLit(String s, long pool);
+		private static native long initApp(String fun, Expr[] args, long pool);
+
 		private void writeObject(ObjectOutputStream out) throws IOException {
 			out.writeObject(showExpr(ref));
 		}
 		
 		private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
 			Expr e = readExpr((String) in.readObject());
-			pool = e.pool;
-			gr   = e.gr;
-			ref  = e.ref;
+			pool   = e.pool;
+			master = e.master;
+			ref    = e.ref;
 		}
 }
diff --git a/src/runtime/java/org/grammaticalframework/pgf/ExprBuilder.java b/src/runtime/java/org/grammaticalframework/pgf/ExprBuilder.java
deleted file mode 100644
index a34a6c19d..000000000
--- a/src/runtime/java/org/grammaticalframework/pgf/ExprBuilder.java
+++ /dev/null
@@ -1,16 +0,0 @@
-package org.grammaticalframework.pgf;
-
-public class ExprBuilder {
-	public ExprBuilder() {
-		
-	}
-
-	ExprBuilder(long poolRef) {
-	}
-
-	public native Expr mkApp(String fun, Expr... args);
-
-	public native Expr mkLiteral(String s);
-	public native Expr mkLiteral(int n);
-	public native Expr mkLiteral(double d);
-}
diff --git a/src/runtime/java/org/grammaticalframework/pgf/LiteralCallback.java b/src/runtime/java/org/grammaticalframework/pgf/LiteralCallback.java
index 4292a4116..87e832ae2 100644
--- a/src/runtime/java/org/grammaticalframework/pgf/LiteralCallback.java
+++ b/src/runtime/java/org/grammaticalframework/pgf/LiteralCallback.java
@@ -1,5 +1,23 @@
 package org.grammaticalframework.pgf;
 
 public interface LiteralCallback {
-	public int match(Concr concr, int lin_idx, ExprBuilder builder, String sentence, int start_offset);
+	public CallbackResult match(int lin_idx, String sentence, int start_offset);
+	
+	public static class CallbackResult {
+		private ExprProb ep;
+		private int offset;
+		
+		public CallbackResult(ExprProb ep, int offset) {
+			this.ep     = ep;
+			this.offset = offset;
+		}
+		
+		public ExprProb getExprProb() {
+			return ep;
+		}
+		
+		public int getOffset() {
+			return offset;
+		}
+	}
 }
diff --git a/src/runtime/java/org/grammaticalframework/pgf/NercLiteralCallback.java b/src/runtime/java/org/grammaticalframework/pgf/NercLiteralCallback.java
index ad1036c56..72f24e712 100644
--- a/src/runtime/java/org/grammaticalframework/pgf/NercLiteralCallback.java
+++ b/src/runtime/java/org/grammaticalframework/pgf/NercLiteralCallback.java
@@ -1,7 +1,36 @@
 package org.grammaticalframework.pgf;
 
 public class NercLiteralCallback implements LiteralCallback {
-	public int match(Concr concr, int lin_idx, ExprBuilder builder, String sentence, int start_offset) {
-		return start_offset;
+	public CallbackResult match(int lin_idx, String sentence, int offset) {
+		StringBuilder sbuilder = new StringBuilder();
+
+		int i = 0;
+		int end_offset = offset;
+		while (offset < sentence.length() &&
+			   Character.isUpperCase(sentence.charAt(offset))) {
+			if (i > 0)
+				sbuilder.append(' ');
+			i++;
+
+			while (offset < sentence.length() &&
+			       !Character.isWhitespace(sentence.charAt(offset))) {
+				sbuilder.append(sentence.charAt(offset));
+				offset++;
+			}
+
+			end_offset = offset;
+			while (offset < sentence.length() &&
+			       Character.isWhitespace(sentence.charAt(offset))) {
+				offset++;
+			}
+		}
+
+		if (i > 0) {
+			Expr expr = new Expr(sbuilder.toString());
+			expr = new Expr("MkSymb", expr);
+			return new CallbackResult(new ExprProb(expr, 0), end_offset);
+		}
+
+		return null;
 	}
 }
diff --git a/src/runtime/java/org/grammaticalframework/pgf/Pool.java b/src/runtime/java/org/grammaticalframework/pgf/Pool.java
index 68a690871..3a39babdf 100644
--- a/src/runtime/java/org/grammaticalframework/pgf/Pool.java
+++ b/src/runtime/java/org/grammaticalframework/pgf/Pool.java
@@ -1,15 +1,20 @@
 package org.grammaticalframework.pgf;
 
-class Pool {
-	private long ref;
-	
+public class Pool {
+	final long ref;
+
 	public Pool(long ref) {
 		this.ref = ref;
 	}
-	
+
+	public Pool() {
+		this.ref = alloc();
+	}
+
 	public void finalize() {
 		free(ref);
 	}
-	
-	private native void free(long ref);
+
+	public static native long alloc();
+	public static native void free(long ref);
 }