mojo: Starting serialization for python bindings.

mojo/public/tools/bindings/generators/mojom_python_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 Python source files from a mojom.Module."""
 
 import re
 from itertools import ifilter
 
 import mojom.generate.generator as generator
@@ skipping 22 matching lines @@
   mojom.NULLABLE_HANDLE:       "_descriptor.TYPE_NULLABLE_HANDLE",
   mojom.NULLABLE_DCPIPE:       "_descriptor.TYPE_NULLABLE_HANDLE",
   mojom.NULLABLE_DPPIPE:       "_descriptor.TYPE_NULLABLE_HANDLE",
   mojom.NULLABLE_MSGPIPE:      "_descriptor.TYPE_NULLABLE_HANDLE",
   mojom.NULLABLE_SHAREDBUFFER: "_descriptor.TYPE_NULLABLE_HANDLE",
 }
 
 # int64 integers are not handled by array.array. int64/uint64 array are
 # supported but storage is not optimized (ie. they are plain python list, not
 # array.array)
-_kind_to_typecode = {
-  mojom.INT8:   "'b'",
-  mojom.UINT8:  "'B'",
-  mojom.INT16:  "'h'",
-  mojom.UINT16: "'H'",
-  mojom.INT32:  "'i'",
-  mojom.UINT32: "'I'",
-  mojom.FLOAT:  "'f'",
-  mojom.DOUBLE: "'d'",
+_kind_to_typecode_for_array = {

[sdefresne, 2014/09/15 08:46:54]

nit: _kind_to_typecode_for_native_array

[qsr, 2014/09/15 11:01:53]

Done.

+  mojom.INT8:   "b",
+  mojom.UINT8:  "B",
+  mojom.INT16:  "h",
+  mojom.UINT16: "H",
+  mojom.INT32:  "i",
+  mojom.UINT32: "I",
+  mojom.FLOAT:  "f",
+  mojom.DOUBLE: "d",
 }
 
+_kind_to_typecode = dict(_kind_to_typecode_for_array)
+_kind_to_typecode.update({
+  mojom.INT64:                 "q",
+  mojom.UINT64:                "Q",
+  mojom.HANDLE:                "i",
+  mojom.DCPIPE:                "i",
+  mojom.DPPIPE:                "i",
+  mojom.MSGPIPE:               "i",
+  mojom.SHAREDBUFFER:          "i",
+  mojom.NULLABLE_HANDLE:       "i",
+  mojom.NULLABLE_DCPIPE:       "i",
+  mojom.NULLABLE_DPPIPE:       "i",
+  mojom.NULLABLE_MSGPIPE:      "i",
+  mojom.NULLABLE_SHAREDBUFFER: "i",
+})
+
 
 def NameToComponent(name):
   # insert '_' between anything and a Title name (e.g, HTTPEntry2FooBar ->
   # HTTP_Entry2_FooBar)
   name = re.sub('([^_])([A-Z][^A-Z_]+)', r'\1_\2', name)
   # insert '_' between non upper and start of upper blocks (e.g.,
   # HTTP_Entry2_FooBar -> HTTP_Entry2_Foo_Bar)
   name = re.sub('([^A-Z_])([A-Z])', r'\1_\2', name)
   return [x.lower() for x in name.split('_')]
 
@@ skipping 42 matching lines @@
 
 def GetStructClass(kind):
   name = []
   if kind.imported_from:
     name.append(kind.imported_from['python_module'])
   name.append(GetNameForElement(kind))
   return '.'.join(name)
 
 def GetFieldType(kind, field=None):
   if mojom.IsAnyArrayKind(kind):
-    if kind.kind in _kind_to_typecode:
-      arguments = [ _kind_to_typecode[kind.kind] ]
-    else:
-      arguments = [ GetFieldType(kind.kind) ]
+    arguments = []
+    if kind.kind in _kind_to_typecode_for_array:
+      arguments.append('\'%s\'' %_kind_to_typecode_for_array[kind.kind])

[sdefresne, 2014/09/15 08:46:54]

nit: you can use '%r' instead of '\'%s\'' to get a quoted string, I think it is
cleaner.

[qsr, 2014/09/15 11:01:53]

Done.

+    elif kind.kind != mojom.BOOL:
+      arguments.append(GetFieldType(kind.kind))
     if mojom.IsNullableKind(kind):
       arguments.append("nullable=True")
     if mojom.IsFixedArrayKind(kind):
       arguments.append("length=%d" % kind.length)
-    if kind.kind in _kind_to_typecode:
-      return "_descriptor.NativeArrayType(%s)" % ", ".join(arguments)
-    else:
-      return "_descriptor.PointerArrayType(%s)" % ", ".join(arguments)
+    array_type = 'GenericArrayType'
+    if kind.kind == mojom.BOOL:
+      array_type = 'BooleanArrayType'
+    elif kind.kind in _kind_to_typecode_for_array:
+      array_type = 'NativeArrayType'
+    return "_descriptor.%s(%s)" % (array_type, ", ".join(arguments))
 
   if mojom.IsStructKind(kind):
     arguments = [ GetStructClass(kind) ]
     if mojom.IsNullableKind(kind):
       arguments.append("nullable=True")
     return "_descriptor.StructType(%s)" % ", ".join(arguments)
 
   if mojom.IsEnumKind(kind):
     return GetFieldType(mojom.INT32)
 
   return _kind_to_type.get(kind, "_descriptor.TYPE_NONE")
 
+def GetPackedFormatString(struct):
+  res = '='
+  for byte in struct.bytes:
+    if len(byte.packed_fields) > 1:
+      res += 'B'
+    else:
+      for packed_field in byte.packed_fields:
+        kind = packed_field.field.kind
+        if mojom.IsEnumKind(kind):
+          res += 'i'
+        else:
+          res += _kind_to_typecode.get(packed_field.field.kind, 'Q')
+    if byte.is_padding:
+      res += 'x'
+  return res
+
 def GetFieldDescriptor(packed_field):
   field = packed_field.field
+  class_name = 'SingleFieldGroup'
+  if field.kind == mojom.BOOL:
+    class_name = 'FieldDescriptor'
   arguments = [ '\'%s\'' % field.name ]
   arguments.append(GetFieldType(field.kind, field))
-  arguments.append(str(packed_field.offset))
-  if field.kind == mojom.BOOL:
-    arguments.append('bit_offset=%d' % packed_field.bit)
+  arguments.append(str(packed_field.field.ordinal))
   if field.default:
     if mojom.IsStructKind(field.kind):
       arguments.append('default_value=True')
     else:
       arguments.append('default_value=%s' % ExpressionToText(field.default))
-  return '_descriptor.FieldDescriptor(%s)' % ', '.join(arguments)
+  return '_descriptor.%s(%s)' % (class_name, ', '.join(arguments))
+
+def GetFieldGroup(byte):
+  if len(byte.packed_fields) > 1:
+    descriptors = map(GetFieldDescriptor, byte.packed_fields)
+    return '_descriptor.BooleanGroup([%s])' % ', '.join(descriptors)
+  for packed_field in byte.packed_fields:
+    return GetFieldDescriptor(packed_field)

[sdefresne, 2014/09/15 11:14:46]

This return in a for loop is strange. Do you only want to return a value for the
first item in byte.packed_fields? What about instead directly writing "return
GetFieldDescriptor(byte.packed_fields[0])" instead? This make it obvious. With
maybe an assertion that the list is not empty.

[qsr, 2014/09/15 11:42:00]

 Refactored by asserting the list has a single element.

+  print byte

[sdefresne, 2014/09/15 08:46:55]

Are those two lines debug? Since the last line is "assert False", I would think
that this function is never called (or at least that you never tested it).
Should it be removed or else tested?

[qsr, 2014/09/15 11:01:53]

 The assert False is correct, the print was just for debugging, and should not
be there. Removed.

[sdefresne, 2014/09/15 11:14:46]

Oh, you mean this line should not be reached? What about using the "assert
condition, error message" syntax to make it obvious this should not be reached.

[qsr, 2014/09/15 11:42:00]

 Removed, asserting the list has a single element instead.

+  assert False
 
 def ComputeStaticValues(module):
   in_progress = set()
   computed = set()
 
   def GetComputedValue(named_value):
     if isinstance(named_value, mojom.EnumValue):
       field = next(ifilter(lambda field: field.name == named_value.name,
                            named_value.enum.fields), None)
       if not field:
@@ skipping 59 matching lines @@
     for constant in struct.constants:
       ResolveConstant(constant)
     for enum in struct.enums:
       ResolveEnum(enum)
     for field in struct.fields:
       if isinstance(field.default, (mojom.ConstantValue, mojom.EnumValue)):
         field.default.computed_value = GetComputedValue(field.default)
 
   return module
 
+_HEADER_SIZE = 8
+
 class Generator(generator.Generator):
 
   python_filters = {
     'expression_to_text': ExpressionToText,
-    'field_descriptor': GetFieldDescriptor,
+    'field_group': GetFieldGroup,
     'name': GetNameForElement,
+    'packed_format_string': GetPackedFormatString,
+    'struct_size': lambda ps: ps.GetTotalSize() + _HEADER_SIZE,
   }
 
   @UseJinja('python_templates/module.py.tmpl', filters=python_filters)
   def GeneratePythonModule(self):
     return {
       'imports': self.GetImports(),
       'enums': self.module.enums,
       'module': ComputeStaticValues(self.module),
       'structs': self.GetStructs(),
     }
 
   def GenerateFiles(self, args):
     self.Write(self.GeneratePythonModule(),
                '%s.py' % self.module.name.replace('.mojom', '_mojom'))
 
   def GetImports(self):
     for each in self.module.imports:
       each['python_module'] = each['module_name'].replace('.mojom', '_mojom')
     return self.module.imports
 
   def GetJinjaParameters(self):
     return {
       'lstrip_blocks': True,
       'trim_blocks': True,
     }