Generate java bindings for constants.

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

Index: mojo/public/tools/bindings/generators/mojom_java_generator.py
diff --git a/mojo/public/tools/bindings/generators/mojom_java_generator.py b/mojo/public/tools/bindings/generators/mojom_java_generator.py
new file mode 100644
index 0000000000000000000000000000000000000000..b514ecb553b7a7f43d798854dd03e516db22af2b
--- /dev/null
+++ b/mojo/public/tools/bindings/generators/mojom_java_generator.py
@@ -0,0 +1,272 @@
+# Copyright 2013 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 os
+
+import mojom.generate.generator as generator
+import mojom.generate.module as mojom
+import mojom.generate.pack as pack
+from mojom.generate.template_expander import UseJinja
+
+
+GENERATOR_PREFIX = 'java'

[rmcilroy, 2014/05/25 22:55:10]

Is this needed - it doesn't seem to be referenced.

[qsr, 2014/05/26 08:41:20]

 It is used by mojo/public/tools/bindings/mojom_bindings_generator.py do filter
arguments passed to this generator.

+
+_HEADER_SIZE = 8
+
+_spec_to_java_type = {
+  'b':     "boolean",
+  'd':     "double",
+  'f':     "float",
+  'h:d:c': "org.chromium.mojo.system.DataPipe.ConsumerHandle",
+  'h:d:p': "org.chromium.mojo.system.DataPipe.ProducerHandle",
+  'h:m':   "org.chromium.mojo.system.MessagePipeHandle",
+  'h':     "org.chromium.mojo.system.UntypedHandle",
+  'h:s':   "org.chromium.mojo.system.SharedBufferHandle",
+  'i16':   "short",
+  'i32':   "int",
+  'i64':   "long",
+  'i8':    "byte",
+  's':     "String",
+  'u16':   "short",
+  'u32':   "int",
+  'u64':   "long",
+  'u8':    "byte",
+}
+
+_spec_to_decode_method = {
+  'b':     "readBoolean",
+  'd':     "readDouble",
+  'f':     "readFloat",
+  'h:d:c': "readConsumerHandle",
+  'h:d:p': "readProducerHandle",
+  'h:m':   "readMessagePipeHandle",
+  'h':     "readUntypedHandle",
+  'h:s':   "readSharedBufferHandle",
+  'i16':   "readShort",
+  'i32':   "readInt",
+  'i64':   "readLong",
+  'i8':    "readByte",
+  's':     "readString",
+  'u16':   "readShort",
+  'u32':   "readInt",
+  'u64':   "readLong",
+  'u8':    "readByte",
+}
+
+
+def DecodeMethod(kind):
+  if isinstance(kind, mojom.Array):
+    return DecodeMethod(kind.kind) + 's'
+  if isinstance(kind, mojom.Enum):
+    return DecodeMethod(mojom.INT32)
+  if isinstance(kind, mojom.Interface):
+    return "readServiceInterface"
+  return _spec_to_decode_method[kind.spec]
+
+def NamespaceToArray(namespace):

[rmcilroy, 2014/05/25 22:55:10]

I think this should be called PackageToArray(package): for Java

[qsr, 2014/05/26 08:41:20]

 Removed.

+  return namespace.split('.')
+
+def GetNameFromString(string):

[rmcilroy, 2014/05/25 22:55:10]

I would call this "UpperCamelCase" and move it with the other CamelCase, etc
functions.

[qsr, 2014/05/26 08:41:20]

 Refactored naming function. This method doesn't exist anymore.

+  return CapitalizeFirst(CamelCase(string))
+
+def GetName(kind):

[rmcilroy, 2014/05/25 22:55:10]

I would get rid of this method - the name is confusing compared to
GetNameForKind, and it is easy enough to just call UpperCamelCase(kind.name)
where it is needed.

[qsr, 2014/05/26 08:41:20]

Done.

+  return GetNameFromString(kind.name)
+
+def GetPackage(module):
+  if 'JavaPackage' in module.attributes:
+    package = module.attributes['JavaPackage']
+    if isinstance(package, basestring):
+      return package
+    assert package[0] == 'EXPRESSION'

[rmcilroy, 2014/05/25 22:55:10]

It's probably clearer to include "else" branches even if the "if" returns - e.g:

if 'JavaPackage' in module.attributes:
  package = module.attributes['JavaPackage']
  if isinstance(package, basestring):
    return package
  else:
    assert package[0] == 'EXPRESSION'
    assert len(package[1]) == 1
    return package[1][0][1:-1].encode('string_escape')
else:
  return "org.chromium.mojom." + module.namespace

(also lots of other examples below)

[qsr, 2014/05/26 08:41:20]

 That's not the style other python file use. Reversed the first if so that it is
more readable, in the style of:
if x
  return 
...
if y
  return
etc.

+    assert len(package[1]) == 1
+    return package[1][0][1:-1].encode('string_escape')
+  return "org.chromium.mojom." + module.namespace
+
+def GetSuperClass(method):
+  if method:
+    if method.response_parameters:
+      return "org.chromium.mojo.bindings.MessageWithRequestId"
+    return "org.chromium.mojo.bindings.Message"
+  return "org.chromium.mojo.bindings.Struct"

[rmcilroy, 2014/05/25 22:55:10]

I think this would be clearer as:

if not method:
  return "org.chromium.mojo.bindings.Struct"
else if method.response_parameters:
  return "org.chromium.mojo.bindings.MessageWithRequestId"
else:
  return "org.chromium.mojo.bindings.Message"

[qsr, 2014/05/26 08:41:20]

 Method removed until further CL.

+
+def GetFlags(method, is_parameter):

[rmcilroy, 2014/05/25 22:55:10]

Could you remove this until it's used in a later CL please (I'm not sure how it
would be used and would like to review it in context)

[qsr, 2014/05/26 08:41:20]

Done.

+  if method.response_parameters:
+    if is_parameter:
+      return "MESSAGE_EXPECTS_RESPONSE_FLAG"
+    return "MESSAGE_IS_RESPONSE_FLAG"
+  return "0"
+
+def NewArray(kind, size):

[rmcilroy, 2014/05/25 22:55:10]

nit - move below GetMethodName

[qsr, 2014/05/26 08:41:20]

 Removed.

+  if isinstance(kind.kind, mojom.Array):
+    return NewArray(kind.kind, size) + '[]'
+  return 'new %s[%s]' % (GetJavaType(kind.kind), size)
+
+def GetNameHierachy(kind):

[rmcilroy, 2014/05/25 22:55:10]

Could you make GetNameHierarchy an inner function of GetNameForKind - this seems
to be the only place it's used.

[qsr, 2014/05/26 08:41:20]

Done.

+  hierachy = []
+  if kind.parent_kind:
+    hierachy = GetNameHierachy(kind.parent_kind)
+  hierachy.append(kind.name)
+  return hierachy
+
+def GetNameForKind(kind):
+  elements = [GetPackage(kind.module)]
+  elements += GetNameHierachy(kind)
+  return '.'.join(elements)
+
+def GetJavaGetterPrefix(kind):
+  if kind == mojom.BOOL:
+    return "is"
+  return "get"
+
+def GetJavaType(kind):
+  if isinstance(kind, mojom.Struct):
+    return GetNameForKind(kind)
+  if isinstance(kind, mojom.Array):
+    return "%s[]" % GetJavaType(kind.kind)
+  if isinstance(kind, mojom.Interface):
+    return "org.chromium.mojo.bindings.ServiceHandle<%s>" % GetNameForKind(kind)
+  if isinstance(kind, mojom.Enum):
+    return "int"
+  return _spec_to_java_type[kind.spec]
+
+def TranslateConstants(token, module):
+  if isinstance(token, (mojom.NamedValue, mojom.EnumValue)):
+    if isinstance(token,  mojom.EnumValue):
+      entity_value = token.enum_name + '.' + token.name
+    else:
+      entity_value = ConstantName(token)
+      if not token.parent_kind:
+        entity_value = (GetConstantsMainEntityName(token.module) +
+                        '.' + entity_value)
+    if token.parent_kind:
+      return GetJavaType(token.parent_kind) + '.' + entity_value
+    return GetPackage(token.module) + '.' + entity_value

[rmcilroy, 2014/05/25 22:55:10]

Could you please reduce this method to the bare minimum for the Const generation
(I think "return token" should be enough).  I would like to review it in context
with the Enum,Struct,Interface generation CLs if possible.

[qsr, 2014/05/26 08:41:20]

 This is mostly the bare minimum. A constant can reference any other constant or
enum value. Even for this CL, as constant could reference another class level
constant.

 I updated this method to try to be a little clearer.

+  return token
+
+def ExpressionToText(value, module):

[rmcilroy, 2014/05/25 22:55:10]

This looks the same as the method in the CPP bindings generator - could it be
pulled out into a separate utility class in the pylib directory?  The
CapitalizeFirst, CamelCase and UpperCaseConstant methods are also candidates to
move to a utility class.

[qsr, 2014/05/26 08:41:20]

 We can do this in a further CL if you do not mind. Moreover, the
TranslateConstants is completely different, so if we extract it into a
parameter, it really doesn't contain much.

 For the naming method, I guess we can moe it into an utility class, but right
now, this file is the only user. 

[rmcilroy, 2014/05/26 11:13:48]

Doing this in a separate cl is fine. BTW, I was only suggesting moving
ExpressionToText, since as you say TranslateConstants is different per binding
generator.

+  if value[0] != "EXPRESSION":
+    raise Exception("Expected EXPRESSION, got" + value)
+  return "".join(generator.ExpressionMapper(value,
+      lambda token: TranslateConstants(token, module)))
+
+def CapitalizeFirst(string):
+  return string[0].upper() + string[1:]
+
+def CamelCase(string):
+  elements = string.split('_')
+  return elements[0] + ''.join([x.capitalize() for x in elements[1:]])
+
+def UpperCaseConstant(name):
+  def _IsCut(i):
+    if i == 0 or i == len(name):
+      return True
+    if name[i].islower():
+      return False
+    if name[i-1].isupper() and (i == len(name) -1 or name[i+1].isupper()):
+      return False
+    return True
+  pos = [i for i in xrange(len(name) + 1) if _IsCut(i)]
+  parts = [name[pos[j]:pos[j+1]] for j in xrange(len(pos)-1)]
+  return '_'.join([x.upper() for x in parts])

[rmcilroy, 2014/05/25 22:55:10]

I think you could do this more easily with a regex.  How about:

def UpperCaseConstant(name):
  name = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', name)      # insert '_' between
anything and a Title name (e.g, HTTPEntry2FooBar -> HTTP_Entry2_FooBar)
  name = re.sub('(.)([0-9])', r'\1_\2', name)                # insert '_'
between anything and a number (e.g, HTTP_Entry2_FooBar -> HTTP_Entry_2_FooBar)
  name = re.sub('([a-z0-9])([A-Z])', r'\1_\2', name)    # insert '_' between
lower or number blocks and start of upper blocks (e.g., HTTP_Entry_2_FooBar ->
HTTP_Entry_2_Foo_Bar)
  return name.upper()
   

[qsr, 2014/05/26 08:41:20]

 This has been completely refactored.

+
+def DefaultValueConstant(field):
+  return 'DEFAULT_' + UpperCaseConstant(GetName(field))

[rmcilroy, 2014/05/25 22:55:10]

Please remove this until the CL where it is used.

[qsr, 2014/05/26 08:41:20]

Done.

+
+def FieldName(field):
+  return 'm' + GetName(field)
+
+def ConstantName(constant):
+  main_name = constant.name
+  if main_name[0] == 'k':
+    main_name = main_name[1:]
+  return UpperCaseConstant(main_name)
+
+def IsPointerArrayKind(kind):

[rmcilroy, 2014/05/25 22:55:10]

Please remove IsPointerArrayKind, GetResponseStructFromMethod and
GetStructFromMethod and GetMethodName until the CL where they are used.

[qsr, 2014/05/26 08:41:20]

Done.

+  if not isinstance(kind, mojom.Array):
+    return False
+  sub_kind = kind.kind
+  return generator.IsObjectKind(sub_kind)
+
+def GetResponseStructFromMethod(method):
+  return generator.GetDataHeader(
+      False, generator.GetResponseStructFromMethod(method))
+
+def GetStructFromMethod(method):
+  return generator.GetDataHeader(
+      False, generator.GetStructFromMethod(method))
+
+def GetMethodName(method):
+  return (UpperCaseConstant(method.interface.name) + "_" +
+          UpperCaseConstant(method.name) + "_NAME")
+
+def GetConstantsMainEntityFullyQualifiedName(module):

[rmcilroy, 2014/05/25 22:55:10]

This doesn't seem to be used - can it be removed (or at least removed from this
CL until it's needed)?

[qsr, 2014/05/26 08:41:20]

 This is now used.

+  package = GetPackage(module)
+  return GetPackage(module) + '.' + GetConstantsMainEntityName(module)
+
+def GetConstantsMainEntityName(module):
+  return (GetNameFromString(module.path.split('/')[-1].rsplit('.', 1)[0]) +

[rmcilroy, 2014/05/25 22:55:10]

Please add a comment describing that this is building a name by extracting the
mojom's filename and prepending it to Constants.  If you could also add the
annotation support as discussed that would be great (feel free to add it in a
separate CL if you prefer though).

[qsr, 2014/05/26 08:41:20]

 Added the comment. I'd rather do the annotation in another targeted CL.

+          'Constants')
+
+class Generator(generator.Generator):
+
+  java_filters = {
+    "camelcase": CamelCase,
+    "capitalize_first": CapitalizeFirst,
+    "default_value_constant": DefaultValueConstant,
+    "decode_method": DecodeMethod,
+    "expression_to_text": ExpressionToText,
+    "field_name": FieldName,
+    "flags": GetFlags,
+    "is_bool": lambda kind: kind == mojom.BOOL,
+    "is_array_kind": lambda kind: isinstance(kind, mojom.Array),
+    "is_object_kind": generator.IsObjectKind,
+    "is_pointer_array_kind": IsPointerArrayKind,
+    "is_string_kind": generator.IsStringKind,
+    "is_struct_kind": lambda kind: isinstance(kind, mojom.Struct),
+    "java_getter_prefix": GetJavaGetterPrefix,
+    "java_type": GetJavaType,
+    "method_name": GetMethodName,
+    "new_array": NewArray,
+    "response_struct_from_method": GetResponseStructFromMethod,
+    "struct_from_method": GetStructFromMethod,
+    "struct_size": lambda ps: ps.GetTotalSize() + _HEADER_SIZE,
+    "super_class": GetSuperClass,
+    "constant_name": ConstantName,
+    "verify_token_type": generator.VerifyTokenType,
+  }
+
+  def GetJinjaExports(self):
+    return {
+      "interfaces": self.module.interfaces,
+      "kinds": self.module.kinds,
+      "method_structs": self.GetStructsFromMethods(),

[rmcilroy, 2014/05/25 22:55:10]

I can't see any uses of "method_structs" either here or in the mega CL - can it
be removed?

[qsr, 2014/05/26 08:41:20]

Done.

+      "module": self.module,
+      "namespace": self.module.namespace,
+      "package": GetPackage(self.module),
+    }
+
+  @UseJinja("java_templates/constants.java.tmpl", filters=java_filters,
+            lstrip_blocks=True, trim_blocks=True)
+  def GenerateConstantsSource(self, module):
+    exports = self.GetJinjaExports()
+    exports.update({"main_entity": GetConstantsMainEntityName(module),
+                    "constants": module.constants})
+    return exports
+
+  def GenerateFiles(self, unparsed_args):
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--java_output_directory", dest="java_output_directory")
+    args = parser.parse_args(unparsed_args)
+    if self.output_dir and args.java_output_directory:
+      self.output_dir = os.path.join(args.java_output_directory,
+                                     GetPackage(self.module).replace('.', '/'))
+      if not os.path.exists(self.output_dir):
+        os.makedirs(self.output_dir)
+
+    if self.module.constants:
+      self.Write(self.GenerateConstantsSource(self.module),
+                 "%s.java" % GetConstantsMainEntityName(self.module))