[GR-18308] Fix up another case how Jython imports may be used

PullRequest: graalpython/669

Author: timfel

CHANGELOG.md

@@ -21,7 +21,7 @@ language runtime. The main focus is on user-observable behavior of the engine.
 * Improve performance of our parser
 * Improve performance of catching exceptions when the exception does not leave the handler block and the traceback is not accessed
 * Improve performance of Java interop when Python objects are accessed from Java
-* Add a new `--python.EmulateJython` flag to support importing Java classes using normal Python import syntax when the package is known and to catch Java exceptions from Python code
+* Add a new `--python.EmulateJython` flag to support importing Java classes using normal Python import syntax and to catch Java exceptions from Python code
 * Update standard library to Python 3.7.4
 * Initial implementatin of PEP 498 -- Literal String Interpolation
 

graalpython/lib-graalpython/java.py

@@ -127,38 +127,43 @@ def exec_module(module):
 
 
 class JavaImportFinder:
+    def is_type(self, name):
+        try:
+            type(name)
+            return True
+        except KeyError:
+            return False
+
     if sys.graal_python_jython_emulation_enabled:
-        @staticmethod
-        def find_spec(fullname, path, target=None):
+        def find_spec(self, fullname, path, target=None):
             # Because of how Jython allows you to import classes that have not
-            # been loaded, yet, we need attempt to load types with the full
-            # string. This will ensure that if there is such a Java class, its
-            # package will have been initialized and thus the is_java_package
-            # check below will work
-            try:
-                type(__jython_current_import__())
-            except KeyError:
-                pass
-            # continue normally with import
-            if JavaPackageLoader.is_java_package(fullname):
-                return _frozen_importlib.ModuleSpec(fullname, JavaPackageLoader, is_package=True)
+            # been loaded, yet, we need attempt to load types very eagerly.
+            if self.is_type(fullname):
+                # the fullname is already a type, let's load it
+                return _frozen_importlib.ModuleSpec(fullname, JavaTypeLoader, is_package=False)
             else:
-                try:
-                    type(fullname)
-                    return _frozen_importlib.ModuleSpec(fullname, JavaTypeLoader, is_package=False)
-                except KeyError:
-                    pass
+                current_import_name = __jython_current_import__()
+                if current_import_name and self.is_type(current_import_name):
+                    # We are currently handling an import that will lead to a
+                    # Java type. The fullname is not a type itself, so it must
+                    # be a package, not an enclosing class.
+                    return _frozen_importlib.ModuleSpec(fullname, JavaPackageLoader, is_package=True)
+                else:
+                    # We are not currently handling an import statement, and the
+                    # fullname is not a type. Thus we can only check if it is a
+                    # known package.
+                    if JavaPackageLoader.is_java_package(fullname):
+                        return _frozen_importlib.ModuleSpec(fullname, JavaPackageLoader, is_package=True)
     else:
-        @staticmethod
-        def find_spec(fullname, path, target=None):
+        def find_spec(self, fullname, path, target=None):
             if path and path == __path__:
                 if fullname.rpartition('.')[2].islower():
                    return _frozen_importlib.ModuleSpec(fullname, JavaPackageLoader, is_package=True)
                 else:
                     return _frozen_importlib.ModuleSpec(fullname, JavaTypeLoader, is_package=False)
 
 
-sys.meta_path.append(JavaImportFinder)
+sys.meta_path.append(JavaImportFinder())
 if sys.graal_python_jython_emulation_enabled:
     __getattr__ = JavaPackageLoader._make_getattr("java")
 else: