Steven Roach HW Type Modeling

java-type-checker/java_type_checker/expressions.py

@@ -31,6 +31,12 @@ def __init__(self, name, declared_type):
         self.name = name                    #: The name of the variable
         self.declared_type = declared_type  #: The declared type of the variable (Type)
 
+    def static_type(self):
+        return self.declared_type
+
+    def check_types(self):
+        pass
+
 
 class Literal(Expression):
     """ A literal value entered in the code, e.g. `5` in the expression `x + 5`.
@@ -39,22 +45,52 @@ def __init__(self, value, type):
         self.value = value  #: The literal value, as a string
         self.type = type    #: The type of the literal (Type)
 
+    def static_type(self):
+        return self.type
+
+    def check_types(self):
+        pass
+
 
 class NullLiteral(Literal):
     def __init__(self):
         super().__init__("null", Type.null)
 
+    def static_type(self):
+        return Type.null
+
+    def check_types(self):
+        pass
+
 
 class MethodCall(Expression):
     """
     A Java method invocation, i.e. `foo.bar(0, 1, 2)`.
     """
     def __init__(self, receiver, method_name, *args):
-        self.receiver = receiver
         self.receiver = receiver        #: The object whose method we are calling (Expression)
         self.method_name = method_name  #: The name of the method to call (String)
         self.args = args                #: The method arguments (list of Expressions)
 
+    def static_type(self):
+        return self.receiver.declared_type.method_named(self.method_name).return_type
+
+    def check_types(self):
+
+        for arg in self.args:
+            arg.check_types()
+
+        receiver_type = self.receiver.static_type()
+        if not receiver_type.is_subtype_of(Type.object):
+            raise JavaTypeError("Type {0} does not have methods".format(receiver_type.name))
+
+        method = receiver_type.method_named(self.method_name) # throws NoMethodError
+        expected_types = method.argument_types
+        actual_types = [arg.static_type() for arg in self.args]
+        call_name = "{0}.{1}()".format(self.receiver.static_type().name, self.method_name)
+
+        check_arguments(expected_types, actual_types, call_name)
+
 
 class ConstructorCall(Expression):
     """
@@ -64,13 +100,49 @@ def __init__(self, instantiated_type, *args):
         self.instantiated_type = instantiated_type  #: The type to instantiate (Type)
         self.args = args                            #: Constructor arguments (list of Expressions)
 
+    def static_type(self):
+        return self.instantiated_type
+
+    def check_types(self):
+
+        for arg in self.args:
+            arg.check_types()
+
+        if not self.instantiated_type.is_instantiable:
+            raise JavaTypeError("Type {0} is not instantiable".format(self.instantiated_type.name))
+
+        expected_types = self.instantiated_type.constructor.argument_types
+        actual_types = [arg.static_type() for arg in self.args]
+        call_name = "{0} constructor".format(self.instantiated_type.name)
+
+        check_arguments(expected_types, actual_types, call_name)
+
 
 class JavaTypeError(Exception):
     """ Indicates a compile-time type error in an expression.
     """
     pass
 
 
+def check_arguments(expected_types, actual_types, call_name):
+    """"
+    Helper to check arguments. Raises JavaTypeError.
+    """
+    if len(expected_types) != len(actual_types):
+        raise JavaTypeError(
+            "Wrong number of arguments for {0}: expected {1}, got {2}".format(
+                call_name,
+                len(expected_types),
+                len(actual_types)))
+
+    for expected_type, actual_type in zip(expected_types, actual_types):
+        if not expected_type.is_supertype_of(actual_type):
+            raise JavaTypeError(
+                "{0} expects arguments of type {1}, but got {2}".format(
+                    call_name,
+                    names(expected_types),
+                    names(actual_types)))
+
 def names(named_things):
     """ Helper for formatting pretty error messages
     """

java-type-checker/java_type_checker/types.py

@@ -12,7 +12,12 @@ def __init__(self, name, direct_supertypes=[]):
     def is_subtype_of(self, other):
         """ True if this type can be used where the other type is expected.
         """
-        return True  # TODO: implement
+        if other is self:
+            return True
+        for direct_supertype in self.direct_supertypes:
+            if other is direct_supertype or direct_supertype.is_subtype_of(other):
+                return True
+        return False
 
     def is_supertype_of(self, other):
         """ Convenience counterpart to is_subtype_of().
@@ -72,6 +77,18 @@ class NullType(Type):
     def __init__(self):
         super().__init__("null")
 
+    def method_named(self, name):
+        """
+        Raises a NoSuchMethod error since null has no method.
+        """
+        raise NoSuchMethod("Cannot invoke method {1}() on null".format(self.name, name))
+
+    def is_subtype_of(self, other):
+        return type(other) == ClassOrInterface
+
+    def is_supertype_of(self, other):
+        return other.is_subtype_of(self)
+
 
 class NoSuchMethod(Exception):
     pass

python-attr-lookup/python-attr-lookup.iml

@@ -20,5 +20,15 @@
         <SOURCES />
       </library>
     </orderEntry>
+    <orderEntry type="module-library" scope="TEST">
+      <library name="JUnit5">
+        <CLASSES>
+          <root url="jar://$APPLICATION_HOME_DIR$/plugins/junit/lib/junit-jupiter-api-5.0.0-M5.jar!/" />
+          <root url="jar://$APPLICATION_HOME_DIR$/plugins/junit/lib/opentest4j-1.0.0-M2.jar!/" />
+        </CLASSES>
+        <JAVADOC />
+        <SOURCES />
+      </library>
+    </orderEntry>
   </component>
 </module>

python-attr-lookup/src/plang/PythonObject.java

@@ -51,7 +51,12 @@ public List<PythonObject> getMRO() {
      * result (i.e. it remembers the list buildMRO() returned and keeps returning it).
      */
     protected List<PythonObject> buildMRO() {
-        throw new UnsupportedOperationException("not implemented yet");
+        if (mro == null) {
+            mro = new ArrayList<>();
+            mro.add(this);
+            mro.addAll(type.buildMRO());
+        }
+        return mro;
     }
 
     /**
@@ -62,7 +67,12 @@ protected List<PythonObject> buildMRO() {
      * @throws PythonAttributeException When there is no attribute on this object with that name.
      */
     public final PythonObject get(String attrName) throws PythonAttributeException {
-        throw new UnsupportedOperationException("not implemented yet");
+        for (PythonObject pythonObject : getMRO()) {
+            if (pythonObject.attrs.containsKey(attrName)) {
+                return pythonObject.attrs.get(attrName);
+            }
+        }
+        throw new PythonAttributeException(this, attrName);
     }
 
     /**
@@ -74,7 +84,7 @@ public final PythonObject get(String attrName) throws PythonAttributeException {
      * @param value Its new value
      */
     public final void set(String attrName, PythonObject value) {
-        throw new UnsupportedOperationException("not implemented yet");
+        attrs.put(attrName, value);
     }
 
     @Override

python-attr-lookup/src/plang/PythonType.java

@@ -41,15 +41,20 @@ public PythonObject getBase() {
 
     @Override
     protected List<PythonObject> buildMRO() {
-        throw new UnsupportedOperationException("not implemented yet");
+        List<PythonObject> mroList = new ArrayList<>();
+        mroList.add(this);
+        if (base != null) {
+            mroList.addAll(base.buildMRO());
+        }
+        return mroList;
     }
 
     /**
      * Creates and returns a new instance of this class, i.e. a PythonObject whose type is
      * this PythonType.
      */
     public PythonObject instantiate() {
-        throw new UnsupportedOperationException("not implemented yet");
+        return new PythonObject(this);
     }
 
     @Override