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..1cfcef313b9573dd51371154110f72524cebf81c
--- /dev/null
+++ b/mojo/public/tools/bindings/generators/mojom_java_generator.py
@@ -0,0 +1,187 @@
+# 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 re
+
+import mojom.generate.generator as generator
+import mojom.generate.module as mojom
+from mojom.generate.template_expander import UseJinja
+
+
+GENERATOR_PREFIX = 'java'
+
+_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',
+}
+
+
+def NameToComponent(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

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

How about using the regex's I suggested in the last CL to transform the string
to '_' separated, the split on '_' (either existing in string or added via regex
transform)?

[qsr, 2014/05/26 12:05:42]

 Done, but I do not find that clearer. Also didn't cut on numbers, as I do not
think it is necessary.

+  if '_' in name:
+    return [item for sublist in [NameToComponent(y) for y in name.split('_')]
+            for item in sublist]
+  pos = [i for i in xrange(len(name) + 1) if _IsCut(i)]
+  return [name[pos[j]:pos[j+1]].lower() for j in xrange(len(pos)-1)]
+
+def CapitalizeFirst(string):
+  return string[0].upper() + string[1:]
+
+def UpperCamelCase(name):
+  return ''.join([CapitalizeFirst(x) for x in NameToComponent(name)])
+
+def CamelCase(name):
+  uccc = UpperCamelCase(name)
+  return uccc[0].lower() + uccc[1:]
+
+def UpperCaseHackerStyle(name):

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

I've never heard of hacker style and can't find it online. Could we just call it
UpperCaseUnderlined or ConstantStyle?

[qsr, 2014/05/26 12:05:42]

 Done. Don't remember where I found it was called hacker style... The web is
indeed completely empty about this...

+  components = NameToComponent(name)
+  if components[0] == 'k':
+    components = components[1:]
+  return '_'.join([x.upper() for x in components])
+
+def GetNameForElement(element):
+  if (isinstance(element, mojom.Enum) or
+      isinstance(element, mojom.Interface) or
+      isinstance(element, mojom.Struct)):
+    return UpperCamelCase(element.name)
+  if (isinstance(element, mojom.Method) or
+      isinstance(element, mojom.Parameter) or
+      isinstance(element, mojom.Field)):
+    return CamelCase(element.name)
+  if isinstance(element,  mojom.EnumValue):
+    return (UpperCamelCase(element.enum_name) + '.' +
+            UpperCaseHackerStyle(element.name))
+  if (isinstance(element, mojom.NamedValue) or
+      isinstance(element, mojom.Constant)):
+    return UpperCaseHackerStyle(element.name)
+  raise Exception("Unexpected element: " % element)
+
+def GetPackage(module):
+  if 'JavaPackage' not in module.attributes:

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

In the case of this function, I still think if/else blocking would be clearer
here, at least between attribute and non attribute approach. Also I think it was
 cleaner having the positive if conditional, without the "not", as you had it
before. 

[qsr, 2014/05/26 12:05:42]

 Move the conditional back. But I really don't like the else. It is nowhere in
the python file used in mojo/

[rmcilroy, 2014/05/27 09:44:34]

OK, we disagree on this, but I'm not going to bikeshed

+    return "org.chromium.mojom." + module.namespace
+  package = module.attributes['JavaPackage']
+  if isinstance(package, basestring):
+    return package
+  assert package[0] == 'EXPRESSION'
+  assert len(package[1]) == 1
+  return package[1][0][1:-1].encode('string_escape')
+
+def GetNameForKind(kind):
+  def _GetNameHierachy(kind):
+    hierachy = []
+    if kind.parent_kind:
+      hierachy = _GetNameHierachy(kind.parent_kind)
+    hierachy.append(kind.name)
+    return hierachy
+
+  elements = [GetPackage(kind.module)]
+  elements += _GetNameHierachy(kind)
+  return '.'.join(elements)
+
+def GetJavaType(kind):
+  if isinstance(kind, (mojom.Struct, mojom.Interface)):
+    return GetNameForKind(kind)
+  if isinstance(kind, mojom.Array):
+    return "%s[]" % GetJavaType(kind.kind)
+  if isinstance(kind, mojom.Enum):
+    return "int"
+  return _spec_to_java_type[kind.spec]
+
+def TranslateConstants(token, module):
+  def _TranslateNamedValue(named_value):
+    entity_value = GetNameForElement(named_value)

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

/s/entity_value/entity_name I think.

[qsr, 2014/05/26 12:05:42]

Done.

+    # Handle the case where named_value is a module level constant:
+    if (not isinstance(named_value, mojom.EnumValue) and

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

This seems a bit confusing to me, how about:

if named_value.parent_kind:
  return GetJavaType(named_value.parent_kind) + '.' + entity_value
else:
  # Handle the case where named_value is a module level constant.
  if isinstance(named_value, mojom.Constant):
    entity_value = GetConstantMainEntityName + '.' + entity_value
  return GetPackage(named_value.module) + '.' + entity_value

Then you can remove GetConstantsMainEntityFullyQualifiedName.

[qsr, 2014/05/26 12:05:42]

 I still think the else after a return is not in any other py file here, so I'd
prefer not to do it. If you want I can add a blank line for better separation.
 The instance is not correct. A constant value (contrary to a Constant
declaration) is just a plain mojom.NamedValue, so the only way to check for this
is checking it is not an EnumValue. But changing the order helps for
readability, so done this, also will get rid of
getConstantsMainEntityFullyQualifiedName(named_value.module) by inlining it
there.

[rmcilroy, 2014/05/27 09:44:34]

Ok, this looks better, thanks.

+        not named_value.parent_kind):
+      return (GetConstantsMainEntityFullyQualifiedName(named_value.module) +
+              '.'+ entity_value)
+    if named_value.parent_kind:
+      return GetJavaType(named_value.parent_kind) + '.' + entity_value
+    return GetPackage(named_value.module) + '.' + entity_value
+
+  if isinstance(token, mojom.NamedValue):
+    return _TranslateNamedValue(token)
+  if re.match('^[0-9]+$', token):

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

Comment that you add Long suffix to all number literals.

[qsr, 2014/05/26 12:05:42]

Done.

+    return token + 'L'
+  return token
+
+def ExpressionToText(value, module):
+  if value[0] != "EXPRESSION":
+    raise Exception("Expected EXPRESSION, got" + value)
+  return "".join(generator.ExpressionMapper(value,
+      lambda token: TranslateConstants(token, module)))
+
+def GetConstantsMainEntityFullyQualifiedName(module):
+  package = GetPackage(module)
+  return GetPackage(module) + '.' + GetConstantsMainEntityName(module)
+
+def GetConstantsMainEntityName(module):
+  # This constructs the name of the embedding classes for module level constants
+  # by extracting the mojom's filename and prepending it to Constants.
+  return (UpperCamelCase(module.path.split('/')[-1].rsplit('.', 1)[0]) +
+          'Constants')
+
+class Generator(generator.Generator):
+
+  java_filters = {
+    "expression_to_text": ExpressionToText,
+    "java_type": GetJavaType,
+    "name": GetNameForElement,
+    "verify_token_type": generator.VerifyTokenType,
+  }
+
+  def GetJinjaExports(self):
+    return {
+      "module": self.module,
+      "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))