loading and unloading of languages in the C runtime and in the Python bindings

11 files changed, 300 insertions, 65 deletions

diff --git a/src/runtime/c/pgf/data.h b/src/runtime/c/pgf/data.h
index 131201132..6bfd5d334 100644
--- a/src/runtime/c/pgf/data.h
+++ b/src/runtime/c/pgf/data.h
@@ -99,6 +99,7 @@ typedef struct {
 	PgfFlags* aflags;
 	PgfCIdMap* funs; // |-> PgfAbsFun*
 	PgfCIdMap* cats; // |-> PgfAbsCat*
+	PgfAbsFun* abs_lin_fun;
 } PgfAbstr;
 
 struct PgfPGF {
@@ -241,6 +242,9 @@ struct PgfConcr {
 	PgfCIdMap* cnccats;
 	PgfCallbacksMap* callbacks;
 	int total_cats;
+	
+	GuPool* pool;     // if the language is loaded separately then this is the pool
+	GuFinalizer fin;  // and this is the finalizer in the pool of the whole grammar
 };
 
 extern GU_DECLARE_TYPE(PgfConcr, abstract);
diff --git a/src/runtime/c/pgf/graphviz.c b/src/runtime/c/pgf/graphviz.c
index 11ecabe40..9410c68a6 100644
--- a/src/runtime/c/pgf/graphviz.c
+++ b/src/runtime/c/pgf/graphviz.c
@@ -260,7 +260,10 @@ pgf_graphviz_parse_tree(PgfConcr* concr, PgfExpr expr, GuOut* out, GuExn* err)
 	GuPool* tmp_pool = gu_local_pool();
 	
 	GuEnum* cts = 
-		pgf_lzr_concretize(concr, expr, tmp_pool);
+		pgf_lzr_concretize(concr, expr, err, tmp_pool);
+	if (!gu_ok(err))
+		return;
+
 	PgfCncTree ctree = gu_next(cts, PgfCncTree, tmp_pool);
 	if (gu_variant_is_null(ctree)) {
 		gu_pool_free(tmp_pool);
diff --git a/src/runtime/c/pgf/linearizer.c b/src/runtime/c/pgf/linearizer.c
index 732bce75a..0f8473639 100644
--- a/src/runtime/c/pgf/linearizer.c
+++ b/src/runtime/c/pgf/linearizer.c
@@ -618,8 +618,17 @@ pgf_cnc_tree_enum_next(GuEnum* self, void* to, GuPool* pool)
 }
 
 PgfCncTreeEnum*
-pgf_lzr_concretize(PgfConcr* concr, PgfExpr expr, GuPool* pool)
+pgf_lzr_concretize(PgfConcr* concr, PgfExpr expr, GuExn* err, GuPool* pool)
 {
+	if (concr->fun_indices == NULL ||
+	    concr->coerce_idx == NULL) {
+		GuExnData* err_data = gu_raise(err, PgfExn);
+		if (err_data) {
+			err_data->data = "The concrete syntax is not loaded";
+			return NULL;
+		}
+	}
+
 	PgfLzn* lzn = gu_new(PgfLzn, pool);
 	lzn->concr = concr;
 	lzn->expr = expr;
@@ -947,7 +956,10 @@ pgf_linearize(PgfConcr* concr, PgfExpr expr, GuOut* out, GuExn* err)
 	GuPool* tmp_pool = gu_local_pool();
 
 	GuEnum* cts =
-		pgf_lzr_concretize(concr, expr, tmp_pool);
+		pgf_lzr_concretize(concr, expr, err, tmp_pool);
+	if (!gu_ok(err))
+		return;
+
 	PgfCncTree ctree = gu_next(cts, PgfCncTree, tmp_pool);
 	if (!gu_variant_is_null(ctree)) {
 		ctree = pgf_lzr_wrap_linref(ctree, tmp_pool);
diff --git a/src/runtime/c/pgf/linearizer.h b/src/runtime/c/pgf/linearizer.h
index e483824b0..b1d96b027 100644
--- a/src/runtime/c/pgf/linearizer.h
+++ b/src/runtime/c/pgf/linearizer.h
@@ -28,7 +28,7 @@ typedef GuEnum PgfCncTreeEnum;
 
 /// Begin enumerating concrete syntax variants.
 PgfCncTreeEnum*
-pgf_lzr_concretize(PgfConcr* concr, PgfExpr expr, GuPool* pool);
+pgf_lzr_concretize(PgfConcr* concr, PgfExpr expr, GuExn* err, GuPool* pool);
 
 typedef struct {
 } PgfLinNonExist;
diff --git a/src/runtime/c/pgf/parser.c b/src/runtime/c/pgf/parser.c
index 676e0ca29..8f58026ed 100644
--- a/src/runtime/c/pgf/parser.c
+++ b/src/runtime/c/pgf/parser.c
@@ -2438,6 +2438,16 @@ pgf_parse_with_heuristics(PgfConcr* concr, PgfCId cat, GuString sentence,
                           GuExn* err,
                           GuPool* pool, GuPool* out_pool)
 {
+	if (concr->sequences == NULL ||
+	    concr->pre_sequences == NULL ||
+	    concr->cnccats == NULL) {
+		GuExnData* err_data = gu_raise(err, PgfExn);
+		if (err_data) {
+			err_data->data = "The concrete syntax is not loaded";
+			return NULL;
+		}
+	}
+
 	// Begin parsing a sentence with the specified category
 	PgfParsing* ps =
 		pgf_parsing_init(concr, cat, 0, sentence, heuristics, err, pool, out_pool);
@@ -2552,6 +2562,14 @@ void
 pgf_lookup_morpho(PgfConcr *concr, GuString sentence,
                   PgfMorphoCallback* callback, GuExn* err)
 {
+	if (concr->sequences == NULL) {
+		GuExnData* err_data = gu_raise(err, PgfExn);
+		if (err_data) {
+			err_data->data = "The concrete syntax is not loaded";
+			return;
+		}
+	}
+
 	PgfSequence* seq = (PgfSequence*)
 		gu_seq_binsearch(concr->sequences, pgf_sequence_order,
 		                 PgfSequence, (void*) sentence);
@@ -2577,21 +2595,23 @@ gu_fullform_enum_next(GuEnum* self, void* to, GuPool* pool)
 	PgfFullFormState* st = gu_container(self, PgfFullFormState, en);
 	PgfFullFormEntry* entry = NULL;
 
-	size_t n_seqs = gu_seq_length(st->sequences);
-	while (st->seq_idx < n_seqs) {
-		PgfSymbols* syms = gu_seq_index(st->sequences, PgfSequence, st->seq_idx)->syms;
-		GuString tokens = pgf_get_tokens(syms, 0, pool);
-		if (strlen(tokens) > 0 &&
-		    gu_seq_index(st->sequences, PgfSequence, st->seq_idx)->idx != NULL) {
-			entry = gu_new(PgfFullFormEntry, pool);
-			entry->tokens = tokens;
-			entry->idx    = gu_seq_index(st->sequences, PgfSequence, st->seq_idx)->idx;
-
+	if (st->sequences != NULL) {
+		size_t n_seqs = gu_seq_length(st->sequences);
+		while (st->seq_idx < n_seqs) {
+			PgfSymbols* syms = gu_seq_index(st->sequences, PgfSequence, st->seq_idx)->syms;
+			GuString tokens = pgf_get_tokens(syms, 0, pool);
+			if (strlen(tokens) > 0 &&
+				gu_seq_index(st->sequences, PgfSequence, st->seq_idx)->idx != NULL) {
+				entry = gu_new(PgfFullFormEntry, pool);
+				entry->tokens = tokens;
+				entry->idx    = gu_seq_index(st->sequences, PgfSequence, st->seq_idx)->idx;
+
+				st->seq_idx++;
+				break;
+			}
+			
 			st->seq_idx++;
-			break;
 		}
-		
-		st->seq_idx++;
 	}
 
 	*((PgfFullFormEntry**) to) = entry;
diff --git a/src/runtime/c/pgf/parseval.c b/src/runtime/c/pgf/parseval.c
index c96eac56a..0090a5942 100644
--- a/src/runtime/c/pgf/parseval.c
+++ b/src/runtime/c/pgf/parseval.c
@@ -171,8 +171,15 @@ pgf_parseval(PgfConcr* concr, PgfExpr expr, PgfCId cat,
 {
 	GuPool* pool = gu_new_pool();
 
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), pool);
+
 	GuEnum* en_lins1 =
-		pgf_lzr_concretize(concr, expr, pool);
+		pgf_lzr_concretize(concr, expr, err, pool);
+	if (!gu_ok(err)) {
+		gu_pool_free(pool);
+		return false;
+	}
+
 	PgfCncTree ctree1 = gu_next(en_lins1, PgfCncTree, pool);
 	if (gu_variant_is_null(ctree1)) {
 		gu_pool_free(pool);
@@ -213,7 +220,7 @@ pgf_parseval(PgfConcr* concr, PgfExpr expr, PgfCId cat,
 	}
 
 	GuEnum* en_lins2 =
-		pgf_lzr_concretize(concr, ep->expr, pool);
+		pgf_lzr_concretize(concr, ep->expr, err, pool);
 	PgfCncTree ctree2 = gu_next(en_lins2, PgfCncTree, pool);
 	if (gu_variant_is_null(ctree2)) {
 		gu_pool_free(pool);
diff --git a/src/runtime/c/pgf/reader.c b/src/runtime/c/pgf/reader.c
index 067d0a35d..ba9f3e30f 100644
--- a/src/runtime/c/pgf/reader.c
+++ b/src/runtime/c/pgf/reader.c
@@ -577,6 +577,17 @@ pgf_read_abstract(PgfReader* rdr, PgfAbstr* abstract)
 	
 	abstract->cats = pgf_read_abscats(rdr, abstract);
 	gu_return_on_exn(rdr->err, );
+
+	abstract->abs_lin_fun = gu_new(PgfAbsFun, rdr->opool);
+	abstract->abs_lin_fun->name = "_";
+	abstract->abs_lin_fun->type = gu_new(PgfType, rdr->opool);
+	abstract->abs_lin_fun->type->hypos = NULL;
+	abstract->abs_lin_fun->type->cid = "_";
+	abstract->abs_lin_fun->type->n_exprs = 0;
+	abstract->abs_lin_fun->arity = 0;
+	abstract->abs_lin_fun->defns = NULL;
+	abstract->abs_lin_fun->ep.prob = INFINITY;
+	abstract->abs_lin_fun->ep.expr = gu_null_variant;
 }
 
 static PgfCIdMap*
@@ -864,7 +875,7 @@ pgf_read_funid(PgfReader* rdr, PgfConcr* concr)
 }
 
 static void
-pgf_read_lindefs(PgfReader* rdr, PgfAbsFun* abs_lin_fun, PgfConcr* concr)
+pgf_read_lindefs(PgfReader* rdr, PgfConcr* concr)
 {
 	size_t len = pgf_read_len(rdr);
 	gu_return_on_exn(rdr->err, );
@@ -878,14 +889,14 @@ pgf_read_lindefs(PgfReader* rdr, PgfAbsFun* abs_lin_fun, PgfConcr* concr)
 		ccat->lindefs = gu_new_seq(PgfCncFun*, n_funs, rdr->opool);
 		for (size_t j = 0; j < n_funs; j++) {
 			PgfCncFun* fun = pgf_read_funid(rdr, concr);
-			fun->absfun = abs_lin_fun;
+			fun->absfun = concr->abstr->abs_lin_fun;
 			gu_seq_set(ccat->lindefs, PgfCncFun*, j, fun);
 		}
 	}
 }
 
 static void
-pgf_read_linrefs(PgfReader* rdr, PgfAbsFun* abs_lin_fun, PgfConcr* concr)
+pgf_read_linrefs(PgfReader* rdr, PgfConcr* concr)
 {
 	size_t len = pgf_read_len(rdr);
 	gu_return_on_exn(rdr->err, );
@@ -899,7 +910,7 @@ pgf_read_linrefs(PgfReader* rdr, PgfAbsFun* abs_lin_fun, PgfConcr* concr)
 		ccat->linrefs = gu_new_seq(PgfCncFun*, n_funs, rdr->opool);
 		for (size_t j = 0; j < n_funs; j++) {
 			PgfCncFun* fun = pgf_read_funid(rdr, concr);
-			fun->absfun = abs_lin_fun;
+			fun->absfun = concr->abstr->abs_lin_fun;
 			gu_seq_set(ccat->linrefs, PgfCncFun*, j, fun);
 		}
 	}
@@ -1147,54 +1158,139 @@ pgf_read_ccat_cb(GuMapItor* fn, const void* key, void* value, GuExn* err)
 //	pgf_ccat_set_viterbi_prob(ccat);
 }
 
-static PgfConcr*
-pgf_read_concrete(PgfReader* rdr, PgfAbstr* abstr, PgfAbsFun* abs_lin_fun)
+void
+pgf_read_concrete_content(PgfReader* rdr, PgfConcr* concr)
 {
-	PgfConcr* concr = gu_new(PgfConcr, rdr->opool);
-
-	concr->name = 
-		pgf_read_cid(rdr, rdr->opool);
-	gu_return_on_exn(rdr->err, NULL);
-
-	concr->abstr = abstr;
-
-	concr->cflags =
-		pgf_read_flags(rdr);
-	gu_return_on_exn(rdr->err, NULL);
-	
-	concr->printnames = 
+	concr->printnames =
 		pgf_read_printnames(rdr);
-	gu_return_on_exn(rdr->err, NULL);
-	
-	concr->sequences = 
+	gu_return_on_exn(rdr->err,);
+
+	concr->sequences =
 		pgf_read_sequences(rdr);
-	gu_return_on_exn(rdr->err, NULL);
+	gu_return_on_exn(rdr->err,);
 
 	concr->pre_sequences = gu_new_buf(PgfSequence, rdr->opool);
 
 	concr->cncfuns =
-		pgf_read_cncfuns(rdr, abstr, concr);
-	gu_return_on_exn(rdr->err, NULL);
+		pgf_read_cncfuns(rdr, concr->abstr, concr);
+	gu_return_on_exn(rdr->err,);
 
 	concr->ccats =
 		gu_new_int_map(PgfCCat*, &gu_null_struct, rdr->opool);
 	concr->fun_indices = gu_map_type_new(PgfCncFunOverloadMap, rdr->opool);
 	concr->coerce_idx  = gu_map_type_new(PgfCncOverloadMap, rdr->opool);
-	pgf_read_lindefs(rdr, abs_lin_fun, concr);
-	pgf_read_linrefs(rdr, abs_lin_fun, concr);
+	pgf_read_lindefs(rdr, concr);
+	pgf_read_linrefs(rdr, concr);
 	pgf_read_ccats(rdr, concr);
-	concr->cnccats = pgf_read_cnccats(rdr, abstr, concr);
+	concr->cnccats = pgf_read_cnccats(rdr, concr->abstr, concr);
 	concr->callbacks = pgf_new_callbacks_map(concr, rdr->opool); 
 	concr->total_cats = pgf_read_int(rdr);
 
 	GuMapItor clo1 = { pgf_read_ccat_cb };
 	gu_map_iter(concr->ccats, &clo1, NULL);
+}
+
+static void
+pgf_read_concrete_init_header(PgfConcr* concr)
+{
+	concr->printnames = NULL;
+	concr->sequences  = NULL;
+	concr->pre_sequences = NULL;
+	concr->cncfuns = NULL;
+	concr->ccats = NULL;
+	concr->fun_indices = NULL;
+	concr->coerce_idx = NULL;
+	concr->cnccats = NULL;
+	concr->callbacks = NULL;
+	concr->total_cats = 0;
+}
+
+static void
+gu_concr_fini(GuFinalizer* fin)
+{
+	PgfConcr* concr = gu_container(fin, PgfConcr, fin);
+	
+	if (concr->pool != NULL) {
+		pgf_read_concrete_init_header(concr);
+		gu_pool_free(concr->pool);
+		concr->pool = NULL;
+	}
+}
+
+static PgfConcr*
+pgf_read_concrete(PgfReader* rdr, PgfAbstr* abstr, bool with_content)
+{
+	PgfConcr* concr = gu_new(PgfConcr, rdr->opool);
+
+	concr->name = 
+		pgf_read_cid(rdr, rdr->opool);
+	gu_return_on_exn(rdr->err, NULL);
+
+	concr->abstr = abstr;
+
+	concr->cflags =
+		pgf_read_flags(rdr);
+	gu_return_on_exn(rdr->err, NULL);
+
+	concr->pool = NULL;
+
+	if (with_content)
+		pgf_read_concrete_content(rdr, concr);
+	else {
+		pgf_read_concrete_init_header(concr);
+
+		concr->fin.fn = gu_concr_fini;
+		gu_pool_finally(rdr->opool, &concr->fin);
+	}
+	gu_return_on_exn(rdr->err, NULL);
 
 	return concr;
 }
 
+void
+pgf_concrete_load(PgfConcr* concr, GuIn* in, GuExn* err)
+{
+	if (concr->pool != NULL)
+		return;    // already loaded
+
+	GuPool* pool = gu_new_pool();
+	GuPool* tmp_pool = gu_local_pool();
+
+	PgfReader* rdr = pgf_new_reader(in, pool, tmp_pool, err);
+
+	PgfCId name =
+		pgf_read_cid(rdr, rdr->tmp_pool);
+	gu_return_on_exn(rdr->err, );
+
+	if (strcmp(name, concr->name) != 0) {
+		GuExnData* err_data = gu_raise(rdr->err, PgfExn);
+		if (err_data) {
+			err_data->data = "This file contains different concrete syntax";
+			gu_pool_free(tmp_pool);
+			gu_pool_free(pool);
+			return;
+		}
+	}
+
+	concr->pool = pool;
+
+	pgf_read_flags(rdr);
+	gu_return_on_exn(rdr->err, );
+
+	pgf_read_concrete_content(rdr, concr);
+	gu_return_on_exn(rdr->err, );
+	
+	gu_pool_free(tmp_pool);
+}
+
+void
+pgf_concrete_unload(PgfConcr* concr)
+{
+	gu_concr_fini(&concr->fin);
+}
+
 static PgfCIdMap*
-pgf_read_concretes(PgfReader* rdr, PgfAbstr* abstr)
+pgf_read_concretes(PgfReader* rdr, PgfAbstr* abstr, bool with_content)
 {
 	GuMapType* map_type = (GuMapType*)
 		GU_TYPE_LIT(GuStringMap, _,
@@ -1205,19 +1301,8 @@ pgf_read_concretes(PgfReader* rdr, PgfAbstr* abstr)
 	size_t len = pgf_read_len(rdr);
 	gu_return_on_exn(rdr->err, NULL);
 
-	PgfAbsFun* abs_lin_fun = gu_new(PgfAbsFun, rdr->opool);
-	abs_lin_fun->name = "_";
-	abs_lin_fun->type = gu_new(PgfType, rdr->opool);
-	abs_lin_fun->type->hypos = NULL;
-	abs_lin_fun->type->cid = "_";
-	abs_lin_fun->type->n_exprs = 0;
-	abs_lin_fun->arity = 0;
-	abs_lin_fun->defns = NULL;
-	abs_lin_fun->ep.prob = INFINITY;
-	abs_lin_fun->ep.expr = gu_null_variant;
-
 	for (size_t i = 0; i < len; i++) {
-		PgfConcr* concr = pgf_read_concrete(rdr, abstr, abs_lin_fun);
+		PgfConcr* concr = pgf_read_concrete(rdr, abstr, with_content);
 		gu_return_on_exn(rdr->err, NULL);
 
 		gu_map_put(concretes, concr->name, PgfConcr*, concr);
@@ -1242,7 +1327,9 @@ pgf_read_pgf(PgfReader* rdr) {
 	pgf_read_abstract(rdr, &pgf->abstract);
 	gu_return_on_exn(rdr->err, NULL);
 
-	pgf->concretes = pgf_read_concretes(rdr, &pgf->abstract);
+	bool with_content =
+		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);
 
 	return pgf;
diff --git a/src/runtime/c/pgf/reader.h b/src/runtime/c/pgf/reader.h
index 95dfc855f..7011eea17 100644
--- a/src/runtime/c/pgf/reader.h
+++ b/src/runtime/c/pgf/reader.h
@@ -14,6 +14,12 @@ PgfPGF*
 pgf_read_pgf(PgfReader* rdr);
 
 void
+pgf_concrete_load(PgfConcr* concr, GuIn* in, GuExn* err);
+
+void
+pgf_concrete_unload(PgfConcr* concr);
+
+void
 pgf_reader_done(PgfReader* rdr, PgfPGF* pgf);
 
 #endif // READER_H_
diff --git a/src/runtime/c/utils/pgf-translate.c b/src/runtime/c/utils/pgf-translate.c
index 32f8323ab..b54b760f5 100644
--- a/src/runtime/c/utils/pgf-translate.c
+++ b/src/runtime/c/utils/pgf-translate.c
@@ -24,7 +24,7 @@ print_result(PgfExprProb* ep, PgfConcr* to_concr,
 
 	// Enumerate the concrete syntax trees corresponding
 	// to the abstract tree.
-	GuEnum* cts = pgf_lzr_concretize(to_concr, ep->expr, ppool);
+	GuEnum* cts = pgf_lzr_concretize(to_concr, ep->expr, err, ppool);
 	while (true) {
 		PgfCncTree ctree =
 			gu_next(cts, PgfCncTree, ppool);
diff --git a/src/runtime/java/org/grammaticalframework/pgf/Concr.java b/src/runtime/java/org/grammaticalframework/pgf/Concr.java
index 779d461cc..1594dfa57 100644
--- a/src/runtime/java/org/grammaticalframework/pgf/Concr.java
+++ b/src/runtime/java/org/grammaticalframework/pgf/Concr.java
@@ -27,6 +27,12 @@ public class Concr {
 
 	public native boolean hasLinearization(String id);
 
+	public native void load(String path) throws FileNotFoundException;
+
+	public native void load(InputStream stream);
+
+	public native void unload();
+
 	//////////////////////////////////////////////////////////////////
 	// private stuff
 	
diff --git a/src/runtime/python/pypgf.c b/src/runtime/python/pypgf.c
index 459b5870b..63df93217 100644
--- a/src/runtime/python/pypgf.c
+++ b/src/runtime/python/pypgf.c
@@ -6,6 +6,7 @@
 #include <gu/file.h>
 #include <pgf/pgf.h>
 #include <pgf/linearizer.h>
+#include <pgf/reader.h>
 
 static PyObject* PGFError;
 
@@ -1245,7 +1246,11 @@ Concr_linearize(ConcrObject* self, PyObject *args)
 	if (!gu_ok(err)) {
 		if (gu_exn_caught(err) == gu_type(PgfLinNonExist))
 			Py_RETURN_NONE;
-		else {
+		else if (gu_exn_caught(err) == gu_type(PgfExn)) {
+			GuString msg = (GuString) gu_exn_caught_data(err);
+			PyErr_SetString(PGFError, msg);
+			return NULL;
+		} else {
 			PyErr_SetString(PGFError, "The abstract tree cannot be linearized");
 			return NULL;
 		}
@@ -1481,9 +1486,20 @@ Concr_bracketedLinearize(ConcrObject* self, PyObject *args)
         return NULL;
 
 	GuPool* tmp_pool = gu_local_pool();
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
 	
 	GuEnum* cts = 
-		pgf_lzr_concretize(self->concr, pyexpr->expr, tmp_pool);
+		pgf_lzr_concretize(self->concr, pyexpr->expr, err, tmp_pool);
+	if (!gu_ok(err)) {
+		if (gu_exn_caught(err) == gu_type(PgfExn)) {
+			GuString msg = (GuString) gu_exn_caught_data(err);
+			PyErr_SetString(PGFError, msg);
+			return NULL;
+		} else {
+			PyErr_SetString(PGFError, "The abstract tree cannot be concretized");
+		}
+	}
+
 	PgfCncTree ctree = gu_next(cts, PgfCncTree, tmp_pool);
 	if (gu_variant_is_null(ctree)) {
 		PyErr_SetString(PGFError, "The abstract tree cannot be concretized");
@@ -1531,7 +1547,12 @@ Concr_graphvizParseTree(ConcrObject* self, PyObject *args) {
 	
 	pgf_graphviz_parse_tree(self->concr, pyexpr->expr, out, err);
 	if (!gu_ok(err)) {
-		PyErr_SetString(PGFError, "The parse tree cannot be visualized");
+		if (gu_exn_caught(err) == gu_type(PgfExn)) {
+			GuString msg = (GuString) gu_exn_caught_data(err);
+			PyErr_SetString(PGFError, msg);
+		} else {
+			PyErr_SetString(PGFError, "The parse tree cannot be visualized");
+		}
 		return NULL;
 	}
 
@@ -1581,6 +1602,16 @@ Concr_lookupMorpho(ConcrObject* self, PyObject *args) {
 
 	PyMorphoCallback callback = { { pypgf_collect_morpho }, analyses };
 	pgf_lookup_morpho(self->concr, sent, &callback.fn, err);
+	if (!gu_ok(err)) {
+		if (gu_exn_caught(err) == gu_type(PgfExn)) {
+			GuString msg = (GuString) gu_exn_caught_data(err);
+			PyErr_SetString(PGFError, msg);
+		} else {
+			PyErr_SetString(PGFError, "The lookup failed");
+		}
+		Py_DECREF(analyses);
+		analyses = NULL;
+	}
 
 	gu_pool_free(tmp_pool);
 
@@ -1654,6 +1685,59 @@ Concr_fullFormLexicon(ConcrObject* self, PyObject *args)
 	return (PyObject*) pyres;
 }
 
+static PyObject*
+Concr_load(ConcrObject* self, PyObject *args)
+{
+    const char *fpath;
+    if (!PyArg_ParseTuple(args, "s", &fpath))
+        return NULL;
+
+	GuPool* tmp_pool = gu_local_pool();
+
+	// Create an exception frame that catches all errors.
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+
+	FILE* infile = fopen(fpath, "rb");
+	if (infile == NULL) {
+		PyErr_SetFromErrnoWithFilename(PyExc_IOError, fpath);
+		return NULL;
+	}
+
+	// Create an input stream from the input file
+	GuIn* in = gu_file_in(infile, tmp_pool);
+
+	// Read the PGF grammar.
+	pgf_concrete_load(self->concr, in, err);
+	if (!gu_ok(err)) {
+		if (gu_exn_caught(err) == gu_type(GuErrno)) {
+			errno = *((GuErrno*) gu_exn_caught_data(err));
+			PyErr_SetFromErrnoWithFilename(PyExc_IOError, fpath);
+		} else if (gu_exn_caught(err) == gu_type(PgfExn)) {
+			GuString msg = (GuString) gu_exn_caught_data(err);
+			PyErr_SetString(PGFError, msg);
+			return NULL;
+		} else {
+			PyErr_SetString(PGFError, "The language cannot be loaded");
+		}
+		return NULL;
+	}
+
+	gu_pool_free(tmp_pool);
+
+	Py_RETURN_NONE;
+}
+
+static PyObject*
+Concr_unload(ConcrObject* self, PyObject *args)
+{
+	if (!PyArg_ParseTuple(args, ""))
+        return NULL;
+
+	pgf_concrete_unload(self->concr);
+
+	Py_RETURN_NONE;
+}
+
 static PyGetSetDef Concr_getseters[] = {
     {"name", 
      (getter)Concr_getName, NULL,
@@ -1702,6 +1786,12 @@ static PyMethodDef Concr_methods[] = {
     {"fullFormLexicon", (PyCFunction)Concr_fullFormLexicon, METH_VARARGS,
      "Enumerates all words in the lexicon (useful for extracting full form lexicons)"
     },
+    {"load", (PyCFunction)Concr_load, METH_VARARGS,
+     "Loads the concrete syntax from a .pgf_c file"
+    },
+    {"unload", (PyCFunction)Concr_unload, METH_VARARGS,
+     "Unloads the concrete syntax"
+    },
     {NULL}  /* Sentinel */
 };