added PGF.inferExpr and Type.toString in the Java binding

src/runtime/java/jpgf.c

@@ -172,7 +172,7 @@ Java_org_grammaticalframework_pgf_PGF_getFunctionType(JNIEnv* env, jobject self,
 		return NULL;
 
 	jclass type_class = (*env)->FindClass(env, "org/grammaticalframework/pgf/Type");
-	jmethodID constrId = (*env)->GetMethodID(env, type_class, "<init>", "(Lorg/grammaticalframework/pgf/PGF;J)V");
+	jmethodID constrId = (*env)->GetMethodID(env, type_class, "<init>", "(Ljava/lang/Object;J)V");
 	jobject jtype = (*env)->NewObject(env, type_class, constrId, self, p2l(tp));
 
 	return jtype;
@@ -1191,6 +1191,24 @@ Java_org_grammaticalframework_pgf_Type_getCategory(JNIEnv* env, jobject self)
 	return gu2j_string(env, tp->cid);
 }
 
+JNIEXPORT jstring JNICALL
+Java_org_grammaticalframework_pgf_Type_toString(JNIEnv* env, jobject self)
+{
+	GuPool* tmp_pool = gu_local_pool();
+
+	GuExn* err = gu_exn(tmp_pool);
+	GuStringBuf* sbuf = gu_string_buf(tmp_pool);
+	GuOut* out = gu_string_buf_out(sbuf);
+
+	pgf_print_type(get_ref(env, self), NULL, 0, out, err);
+
+	GuString str = gu_string_buf_freeze(sbuf, tmp_pool);
+	jstring jstr = gu2j_string(env, str);
+
+	gu_pool_free(tmp_pool);
+	return jstr;
+}
+
 JNIEXPORT jobject JNICALL
 Java_org_grammaticalframework_pgf_Generator_generateAll(JNIEnv* env, jclass clazz, jobject jpgf, jstring jstartCat)
 {
@@ -1247,3 +1265,50 @@ Java_org_grammaticalframework_pgf_PGF_compute(JNIEnv* env, jobject self, jobject
 
 	return jexpr;
 }
+
+JNIEXPORT jobject JNICALL
+Java_org_grammaticalframework_pgf_PGF_inferExpr(JNIEnv* env, jobject self, jobject jexpr)
+{
+	GuPool* pool = gu_new_pool();
+	GuPool* tmp_pool = gu_local_pool();
+	GuExn* err = gu_exn(tmp_pool);
+
+	PgfExpr expr =
+		gu_variant_from_ptr((void*) get_ref(env, jexpr));
+	PgfType* tp  =
+		pgf_infer_expr(get_ref(env, self), &expr, err, pool);
+	if (!gu_ok(err)) {
+		if (gu_exn_caught(err, PgfExn)) {
+			GuString msg = (GuString) gu_exn_caught_data(err);
+			throw_string_exception(env, "org/grammaticalframework/pgf/PGFError", msg);
+		} else if (gu_exn_caught(err, PgfTypeError)) {
+			GuString msg = (GuString) gu_exn_caught_data(err);
+			throw_string_exception(env, "org/grammaticalframework/pgf/TypeError", msg);
+ 		} else {
+			throw_string_exception(env, "org/grammaticalframework/pgf/PGFError", "The type cannot be inferred");
+		}
+		gu_pool_free(tmp_pool);
+		gu_pool_free(pool);
+		return NULL;
+	}
+
+	gu_pool_free(tmp_pool);
+
+	jclass pool_class = (*env)->FindClass(env, "org/grammaticalframework/pgf/Pool");
+	jmethodID pool_constrId = (*env)->GetMethodID(env, pool_class, "<init>", "(J)V");
+	jobject jpool = (*env)->NewObject(env, pool_class, pool_constrId, p2l(pool));
+
+	jclass expr_class  = (*env)->GetObjectClass(env, jexpr);
+	jmethodID expr_constrId = (*env)->GetMethodID(env, expr_class, "<init>", "(Lorg/grammaticalframework/pgf/Pool;Ljava/lang/Object;J)V");
+	jexpr = (*env)->NewObject(env, expr_class, expr_constrId, jpool, NULL, p2l(gu_variant_to_ptr(expr)));
+
+	jclass type_class = (*env)->FindClass(env, "org/grammaticalframework/pgf/Type");
+	jmethodID type_constrId = (*env)->GetMethodID(env, type_class, "<init>", "(Ljava/lang/Object;J)V");
+	jobject jtype = (*env)->NewObject(env, type_class, type_constrId, jpool, p2l(tp));
+	
+	jclass typed_expr_class = (*env)->FindClass(env, "org/grammaticalframework/pgf/TypedExpr");
+	jmethodID typed_expr_constrId = (*env)->GetMethodID(env, typed_expr_class, "<init>", "(Lorg/grammaticalframework/pgf/Expr;Lorg/grammaticalframework/pgf/Type;)V");
+	jobject jtyped_expr = (*env)->NewObject(env, typed_expr_class, typed_expr_constrId, jexpr, jtype);
+
+	return jtyped_expr;
+}

src/runtime/java/org/grammaticalframework/pgf/PGF.java

@@ -58,6 +58,10 @@ public class PGF {
 	 */
 	public native Expr compute(Expr expr);
 
+	/** Takes an expression and returns a refined version
+	 * of the expression together with its type */
+	public native TypedExpr inferExpr(Expr expr) throws TypeError;
+
 	//////////////////////////////////////////////////////////////////
 	// private stuff
 	private Pool pool;

src/runtime/java/org/grammaticalframework/pgf/Type.java

@@ -12,15 +12,17 @@ public class Type {
 	 * If the represented type is A1 -> A2 -> ... An -> B, then
 	 * the hypotheses represent the types in A1, A2 ... An. */
 	public native Hypo[] getHypos();
-	
+
+	public native String toString();
+
 	//////////////////////////////////////////////////////////////////
 	// private stuff
-	
-	private PGF gr;
+
+	private Object master;
 	private long ref;
-	
-	private Type(PGF gr, long ref) {
-		this.gr  = gr;
-		this.ref = ref;
+
+	private Type(Object master, long ref) {
+		this.master = master;
+		this.ref    = ref;
 	}
 }

src/runtime/java/org/grammaticalframework/pgf/TypeError.java

@@ -0,0 +1,7 @@
+package org.grammaticalframework.pgf;
+
+public class TypeError extends Exception {
+	public TypeError(String message) {
+		super(message);
+	}
+}

src/runtime/java/org/grammaticalframework/pgf/TypedExpr.java

@@ -0,0 +1,24 @@
+package org.grammaticalframework.pgf;
+
+/** This is just a pair of an expression and its type */
+public class TypedExpr {
+	private Expr expr;
+	private Type type;
+
+	public TypedExpr(Expr expr, Type type) {
+		this.expr = expr;
+		this.type = type;
+	}
+
+	public Expr getExpr() {
+		return expr;
+	}
+
+	public Type getType() {
+		return type;
+	}
+
+	public String toString() {
+		return "<"+expr.toString()+" : "+type.toString()+">";
+	}
+}