mojo: Start generating structs for python bindings

R=pkl@chromium.org,cmasone@chromium.org

Review URL: https://codereview.chromium.org/538613005

Cr-Commit-Position: refs/heads/master@{#294161}

mojo/public/python/mojo/bindings/reflection.py

@@ -18,6 +18,7 @@ class MojoEnumType(type):
 
       This will define a enum with 3 values, A = 0, B = 1 and C = 5.
   """
+
   def __new__(mcs, name, bases, dictionary):
     class_members = {
       '__new__': None,
@@ -37,3 +38,55 @@ class MojoEnumType(type):
 
   def __delattr__(mcs, key):
     raise AttributeError, 'can\'t delete attribute'
+
+
+class MojoStructType(type):
+  """Meta class for structs.
+
+  Usage:
+    class MyStruct(object):
+      __metaclass__ = MojoStructType
+      DESCRIPTOR = {
+        'constants': {
+          'C1': 1,
+          'C2': 2,
+        },
+        'enums': {
+          'ENUM1': [
+            ('V1', 1),
+            'V2',
+          ],
+          'ENUM2': [
+            ('V1', 1),
+            'V2',
+          ],
+        },
+      }
+
+      This will define an struct, with 2 constants C1 and C2, and 2 enums ENUM1
+      and ENUM2, each of those having 2 values, V1 and V2.
+  """
+
+  def __new__(mcs, name, bases, dictionary):
+    class_members = {
+      '__slots__': [],
+    }
+    descriptor = dictionary.pop('DESCRIPTOR', {})
+
+    # Add constants
+    class_members.update(descriptor.get('constants', {}))
+
+    # Add enums
+    enums = descriptor.get('enums', {})
+    for key in enums:
+      class_members[key] = MojoEnumType(key,
+                                        (object,),
+                                        { 'VALUES': enums[key] })
+
+    return type.__new__(mcs, name, bases, class_members)
+
+  def __setattr__(mcs, key, value):
+    raise AttributeError, 'can\'t set attribute'
+
+  def __delattr__(mcs, key):
+    raise AttributeError, 'can\'t delete attribute'

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

@@ -35,6 +35,9 @@ def ConstantStyle(name):
   return '_'.join([x.upper() for x in components])
 
 def GetNameForElement(element):
+  if (mojom.IsEnumKind(element) or mojom.IsInterfaceKind(element) or
+      mojom.IsStructKind(element)):
+    return UpperCamelCase(element.name)
   if isinstance(element, mojom.EnumValue):
     return (GetNameForElement(element.enum) + '.' +
             ConstantStyle(element.name))
@@ -129,6 +132,7 @@ class Generator(generator.Generator):
       'imports': self.GetImports(),
       'enums': self.module.enums,
       'module': ComputeConstantValues(self.module),
+      'structs': self.GetStructs(),
     }
 
   def GenerateFiles(self, args):

mojo/public/tools/bindings/generators/python_templates/module.py.tmpl

+{% from "module_macros.tmpl" import enum_values %}
 # 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.
@@ -18,11 +19,28 @@ import {{import.python_module}}
 {% endif %}
 {% for enum in module.enums %}
 
-class {{enum.name}}(object):
+class {{enum|name}}(object):
   __metaclass__ = _reflection.MojoEnumType
-  VALUES = [
-{%   for field in enum.fields %}
-    ('{{field.name}}', {{field.computed_value}}),
-{%   endfor %}
-  ]
+  VALUES = {{enum_values(enum)|indent(2)}}
+{% endfor %}
+{% for struct in module.structs %}
+
+class {{struct|name}}(object):
+  __metaclass__ = _reflection.MojoStructType
+  DESCRIPTOR = {
+{%   if struct.constants %}
+    'constants': {
+{%     for constant in struct.constants %}
+      '{{constant|name}}': {{constant.value|expression_to_text}},
+{%     endfor %}
+    },
+{%   endif %}
+{%   if struct.enums %}
+    'enums': {
+{%     for enum in struct.enums %}
+      '{{enum|name}}': {{enum_values(enum)|indent(6)}},
+{%     endfor %}
+    },
+{%   endif %}
+  }
 {% endfor %}

mojo/public/tools/bindings/generators/python_templates/module_macros.tmpl

+# 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.
+
+{%- macro enum_values(enum) -%}
+[
+{% for field in enum.fields %}
+  ('{{field.name}}', {{field.computed_value}}),
+{% endfor %}
+]
+{%- endmacro -%}

mojo/public/tools/bindings/mojom.gni

@@ -47,6 +47,7 @@ template("mojom") {
     "$generator_root/generators/js_templates/interface_definition.tmpl",
     "$generator_root/generators/js_templates/module.js.tmpl",
     "$generator_root/generators/js_templates/struct_definition.tmpl",
+    "$generator_root/generators/python_templates/module_macros.tmpl",
     "$generator_root/generators/python_templates/module.py.tmpl",
     "$generator_root/generators/mojom_cpp_generator.py",
     "$generator_root/generators/mojom_js_generator.py",

mojo/public/tools/bindings/mojom_bindings_generator.gypi

@@ -52,6 +52,7 @@
         '<(DEPTH)/mojo/public/tools/bindings/generators/js_templates/interface_definition.tmpl',
         '<(DEPTH)/mojo/public/tools/bindings/generators/js_templates/module.js.tmpl',
         '<(DEPTH)/mojo/public/tools/bindings/generators/js_templates/struct_definition.tmpl',
+        '<(DEPTH)/mojo/public/tools/bindings/generators/python_templates/module_macros.tmpl',
         '<(DEPTH)/mojo/public/tools/bindings/generators/python_templates/module.py.tmpl',
         '<(DEPTH)/mojo/public/tools/bindings/generators/mojom_cpp_generator.py',
         '<(DEPTH)/mojo/public/tools/bindings/generators/mojom_java_generator.py',

mojo/python/tests/bindings_constants_unittest.py

@@ -26,3 +26,14 @@ class ConstantBindingsTest(unittest.TestCase):
     self.assertEquals(sample_service_mojom.FLOAT_NEGATIVE_INFINITY,
                       float('-inf'))
     self.assertTrue(math.isnan(sample_service_mojom.FLOAT_NA_N))
+
+  def testConstantOnStructGeneration(self):
+    self.assertEquals(sample_service_mojom.Foo.FOOBY, "Fooby")
+
+  def testStructImmutability(self):
+    with self.assertRaises(AttributeError):
+      sample_service_mojom.Foo.FOOBY = 0
+    with self.assertRaises(AttributeError):
+      del sample_service_mojom.Foo.FOOBY
+    with self.assertRaises(AttributeError):
+      sample_service_mojom.Foo.BAR = 1

mojo/python/tests/bindings_enums_unittest.py

@@ -7,6 +7,7 @@ import unittest
 # Generated files
 # pylint: disable=F0401
 import sample_import_mojom
+import sample_service_mojom
 
 
 class EnumBindingsTest(unittest.TestCase):
@@ -27,6 +28,13 @@ class EnumBindingsTest(unittest.TestCase):
     self.assertEquals(sample_import_mojom.YetAnotherShape.CIRCLE, 21)
     self.assertEquals(sample_import_mojom.YetAnotherShape.TRIANGLE, 22)
 
+  # Testing that internal enum class have expected constant values.
+  def testInternalEnumGeneration(self):
+    self.assertEquals(sample_service_mojom.Bar.Type.VERTICAL, 1)
+    self.assertEquals(sample_service_mojom.Bar.Type.HORIZONTAL, 2)
+    self.assertEquals(sample_service_mojom.Bar.Type.BOTH, 3)
+    self.assertEquals(sample_service_mojom.Bar.Type.INVALID, 4)
+
   # Testing an enum class cannot be instantiated.
   def testNonInstantiableEnum(self):
     with self.assertRaises(TypeError):