a bit more on the Java to C binding. Now it is possible to load a grammar and query for the list of languages

src/runtime/java/jpgf.c

@@ -1,9 +1,64 @@
 #include <pgf/pgf.h>
 #include <gu/mem.h>
-#include "org_grammaticalframework_PGF.h"
+#include <gu/exn.h>
+#include <alloca.h>
+#include "org_grammaticalframework_pgf_PGF.h"
+
+static jstring
+gu2j_string(JNIEnv *env, GuString s) {
+	GuWord w = s.w_;
+	uint8_t buf[sizeof(GuWord)];
+
+	uint8_t* utf8;
+	size_t len;
+	if (w & 1) {
+		len = (w & 0xff) >> 1;
+		gu_assert(len <= sizeof(GuWord));
+		size_t i = len;
+		while (i > 0) {
+			w >>= 8;
+			buf[--i] = w & 0xff;
+		}
+		utf8 = buf;
+	} else {
+		uint8_t* p = (void*) w;
+		len = (p[0] == 0) ? ((size_t*) p)[-1] : p[0];
+		utf8 = &p[1];
+	}
+
+	const uint8_t* src = utf8;
+
+	jchar* utf16 = alloca(len*sizeof(jchar));
+	jchar* dst   = utf16;
+	while (src-utf8 < len) {
+		GuUCS ucs = gu_utf8_decode(&src);
+		
+		if (ucs <= 0xFFFF) {
+			*dst++ = ucs;
+		} else {
+			ucs -= 0x10000;
+			*dst++ = 0xD800+(ucs >> 10) & 0x3FF;
+			*dst++ = 0xDC00+ucs & 0x3FF;
+		}
+	}
+
+	return (*env)->NewString(env, utf16, dst-utf16);
+}
+
+static PgfPGF*
+get_pgf(JNIEnv *env, jobject self) {
+	jfieldID grId = (*env)->GetFieldID(env, (*env)->GetObjectClass(env, self), "gr", "J");
+	return (PgfPGF*) (*env)->GetLongField(env, self, grId);
+}
+
+static PgfPGF*
+get_concr(JNIEnv *env, jobject self) {
+	jfieldID concrId = (*env)->GetFieldID(env, (*env)->GetObjectClass(env, self), "concr", "J");
+	return (PgfPGF*) (*env)->GetLongField(env, self, concrId);
+}
 
 JNIEXPORT jobject JNICALL 
-Java_org_grammaticalframework_PGF_readPGF(JNIEnv *env, jclass cls, jstring s)
+Java_org_grammaticalframework_pgf_PGF_readPGF(JNIEnv *env, jclass cls, jstring s)
 { 
 	GuPool* pool = gu_new_pool();
 	GuPool* tmp_pool = gu_local_pool();
@@ -19,6 +74,32 @@ Java_org_grammaticalframework_PGF_readPGF(JNIEnv *env, jclass cls, jstring s)
 	(*env)->ReleaseStringUTFChars(env, s, fpath);
 
 	if (!gu_ok(err)) {
+		if (gu_exn_caught(err) == gu_type(GuErrno)) {
+			jclass exception_class = (*env)->FindClass(env, "java/io/FileNotFoundException");
+			if (!exception_class)
+				return NULL;
+			jmethodID constrId = (*env)->GetMethodID(env, exception_class, "<init>", "(Ljava/lang/String;)V");
+			if (!constrId)
+				return NULL;
+			jobject exception = (*env)->NewObject(env, exception_class, constrId, s);
+			if (!exception)
+				return NULL;
+			(*env)->Throw(env, exception);
+		} else {
+			jclass exception_class = (*env)->FindClass(env, "org/grammaticalframework/PGFError");
+			if (!exception_class)
+				return NULL;
+			jmethodID constrId = (*env)->GetMethodID(env, exception_class, "<init>", "(Ljava/lang/String;)V");
+			if (!constrId)
+				return NULL;
+			jstring msg = (*env)->NewStringUTF(env, "The grammar cannot be loaded");
+			if (!msg)
+				return NULL;
+			jobject exception = (*env)->NewObject(env, exception_class, constrId, msg);
+			if (!exception)
+				return NULL;
+			(*env)->Throw(env, exception);
+		}
 		gu_pool_free(pool);
 		gu_pool_free(tmp_pool);
 		return NULL;
@@ -27,12 +108,81 @@ Java_org_grammaticalframework_PGF_readPGF(JNIEnv *env, jclass cls, jstring s)
 	gu_pool_free(tmp_pool);
 
 	jmethodID constrId = (*env)->GetMethodID(env, cls, "<init>", "(JJ)V");
+	return (*env)->NewObject(env, cls, constrId, (jlong) pool, (jlong) pgf);
+}
 
-	return (*env)->NewObject(env, cls, constrId, (long) pool, (long) pgf);
+JNIEXPORT jstring JNICALL 
+Java_org_grammaticalframework_pgf_PGF_getAbstractName(JNIEnv* env, jobject self)
+{
+	return gu2j_string(env, pgf_abstract_name(get_pgf(env, self)));
 }
 
 JNIEXPORT void JNICALL 
-Java_org_grammaticalframework_PGF_free(JNIEnv* env, jclass cls, jlong pool)
+Java_org_grammaticalframework_pgf_PGF_free(JNIEnv* env, jclass cls, jlong pool)
 {
 	gu_pool_free((GuPool*) pool);
 }
+
+typedef struct {
+	GuMapItor fn;
+	JNIEnv *env;
+	jobject grammar;
+	jobject object;
+} JPGFClosure;
+
+static void
+pgf_collect_langs(GuMapItor* fn, const void* key, void* value, GuExn* err)
+{
+	PgfCId name = *((PgfCId*) key);
+    PgfConcr* concr = *((PgfConcr**) value);
+    JPGFClosure* clo = (JPGFClosure*) fn;
+
+	jstring jname = gu2j_string(clo->env, name);
+	
+	jclass map_class = (*clo->env)->GetObjectClass(clo->env, clo->object);
+	jmethodID put_method = (*clo->env)->GetMethodID(clo->env, map_class, "put", "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;");
+
+	jclass concr_class = (*clo->env)->FindClass(clo->env, "org/grammaticalframework/pgf/Concr");
+	jmethodID constrId = (*clo->env)->GetMethodID(clo->env, concr_class, "<init>", "(Lorg/grammaticalframework/pgf/PGF;J)V");
+	jobject jconcr = (*clo->env)->NewObject(clo->env, concr_class, constrId, clo->grammar, (jlong) concr);
+
+	(*clo->env)->CallObjectMethod(clo->env, clo->object, put_method, jname, jconcr);
+}
+
+JNIEXPORT jobject JNICALL
+Java_org_grammaticalframework_pgf_PGF_getLanguages(JNIEnv* env, jobject self)
+{
+	jclass map_class = (*env)->FindClass(env, "java/util/HashMap");
+	if (!map_class)
+		return NULL;
+	jmethodID constrId = (*env)->GetMethodID(env, map_class, "<init>", "()V");
+	if (!constrId)
+		return NULL;
+	jobject languages = (*env)->NewObject(env, map_class, constrId);
+	if (!languages)
+		return NULL;
+
+	PgfPGF* pgf = get_pgf(env, self);
+
+	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);
+
+	JPGFClosure clo = { { pgf_collect_langs }, env, self, languages };
+	pgf_iter_languages(pgf, &clo.fn, err);
+	if (!gu_ok(err)) {
+		gu_pool_free(tmp_pool);
+		return NULL;
+	}
+	
+	gu_pool_free(tmp_pool);
+
+	return languages;
+}
+
+JNIEXPORT jstring JNICALL 
+Java_org_grammaticalframework_pgf_Concr_getName(JNIEnv* env, jobject self)
+{
+	return gu2j_string(env, pgf_concrete_name(get_concr(env, self)));
+}