Mojo: validate nullability in Java bindings.

mojo/public/tools/bindings/generators/mojom_java_generator.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Generates java source files from a mojom.Module."""
 
 import argparse
 import ast
 import os
 import re
@@ skipping 118 matching lines @@
     return ConstantStyle(element.name)
   raise Exception("Unexpected element: " % element)
 
 def GetInterfaceResponseName(method):
   return UpperCamelCase(method.name + 'Response')
 
 def ParseStringAttribute(attribute):
   assert isinstance(attribute, basestring)
   return attribute
 
+def GetJavaTrueFalse(value):
+  return "true" if value else "false"
+
+def GetArrayNullabilityFlags(kind):
+    """Returns nullability flags for an array type, see Decoder.java.
+
+    As we have dedicated decoding functions for arrays, we have to pass
+    nullability information about both the array itself, as well as the array
+    element type there.
+    """
+    assert mojom.IsAnyArrayKind(kind)
+    ARRAY_NULLABLE   = "org.chromium.mojo.bindings.Decoder.ARRAY_NULLABLE"
+    ELEMENT_NULLABLE = "org.chromium.mojo.bindings.Decoder.ELEMENT_NULLABLE"
+    NOTHING_NULLABLE = "org.chromium.mojo.bindings.Decoder.NOTHING_NULLABLE"
+
+    flags_to_set = []
+    if mojom.IsNullableKind(kind):
+        flags_to_set.append(ARRAY_NULLABLE)
+    if mojom.IsNullableKind(kind.kind):
+        flags_to_set.append(ELEMENT_NULLABLE)
+
+    if not flags_to_set:
+        flags_to_set = [NOTHING_NULLABLE]
+    return " | ".join(flags_to_set)
+
+
 @contextfilter
 def DecodeMethod(context, kind, offset, bit):
   def _DecodeMethodName(kind):
     if mojom.IsAnyArrayKind(kind):
       return _DecodeMethodName(kind.kind) + 's'
     if mojom.IsEnumKind(kind):
       return _DecodeMethodName(mojom.INT32)
     if mojom.IsInterfaceRequestKind(kind):
       return "readInterfaceRequest"
     if mojom.IsInterfaceKind(kind):
       return "readServiceInterface"
     return _spec_to_decode_method[kind.spec]
   methodName = _DecodeMethodName(kind)
   params = [ str(offset) ]
   if (kind == mojom.BOOL):
     params.append(str(bit))
+  if mojom.IsReferenceKind(kind):
+    if mojom.IsAnyArrayKind(kind):
+      params.append(GetArrayNullabilityFlags(kind))
+    else:
+      params.append(GetJavaTrueFalse(mojom.IsNullableKind(kind)))
   if mojom.IsInterfaceKind(kind):
     params.append('%s.MANAGER' % GetJavaType(context, kind))
   if mojom.IsAnyArrayKind(kind) and mojom.IsInterfaceKind(kind.kind):
     params.append('%s.MANAGER' % GetJavaType(context, kind.kind))
   return '%s(%s)' % (methodName, ', '.join(params))
 
 @contextfilter
 def EncodeMethod(context, kind, variable, offset, bit):
   params = [ variable, str(offset) ]
   if (kind == mojom.BOOL):
@@ skipping 152 matching lines @@
   java_filters = {
     "interface_response_name": GetInterfaceResponseName,
     "constant_value": ConstantValue,
     "default_value": DefaultValue,
     "decode_method": DecodeMethod,
     "expression_to_text": ExpressionToText,
     "encode_method": EncodeMethod,
     "has_method_with_response": HasMethodWithResponse,
     "has_method_without_response": HasMethodWithoutResponse,
     "is_handle": mojom.IsNonInterfaceHandleKind,
+    "is_nullable_kind": mojom.IsNullableKind,
     "is_pointer_array_kind": IsPointerArrayKind,
     "is_struct_kind": mojom.IsStructKind,
     "java_type": GetJavaType,
+    "java_true_false": GetJavaTrueFalse,
     "method_ordinal_name": GetMethodOrdinalName,
     "name": GetNameForElement,
     "new_array": NewArray,
     "response_struct_from_method": GetResponseStructFromMethod,
     "struct_from_method": GetStructFromMethod,
     "struct_size": lambda ps: ps.GetTotalSize() + _HEADER_SIZE,
   }
 
   def GetJinjaExports(self):
     return {
@@ skipping 72 matching lines @@
   def GetJinjaParameters(self):
     return {
       'lstrip_blocks': True,
       'trim_blocks': True,
     }
 
   def GetGlobals(self):
     return {
       'module': self.module,
     }