Initial commit of the Dart Chrome Extension APIs generators

tools/json_schema_compiler/dart_generator.py

Index: tools/json_schema_compiler/dart_generator.py
diff --git a/tools/json_schema_compiler/dart_generator.py b/tools/json_schema_compiler/dart_generator.py
new file mode 100644
index 0000000000000000000000000000000000000000..a3b1135d1ae2f9fa97a2ff27afcf0cbf437c6cf4
--- /dev/null
+++ b/tools/json_schema_compiler/dart_generator.py
@@ -0,0 +1,569 @@
+# Copyright (c) 2012 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.
+"""
+Generator language component for compiler.py that adds Dart language support.
+
+Pass 'dart' with the -l flag to compiler.py to activate the use of this library.
+"""
+
+from code import Code
+from model import *
+from schema_util import *
+
+import os
+from datetime import datetime
+
+LICENSE = ("""
+// Copyright (c) %s, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.""" %
+    datetime.now().year)
+
+class DartGenerator(object):
+  """A .dart generator for a namespace.
+  """
+
+  def __init__(self, namespace, dart_overrides_dir=None):
+    self._namespace = namespace
+    self._types = namespace.types
+
+    # Build a dictionary of Type Name --> Custom Dart code.
+    self._custom_dart = {}

[not at google - send to devlin, 2013/01/31 02:08:48]

_type_overrides?

[sashab, 2013/01/31 04:41:40]

Done.

+    if dart_overrides_dir is not None:
+      for filename in os.listdir(dart_overrides_dir):
+        if filename.startswith(namespace.unix_name):
+          with open(os.path.join(dart_overrides_dir, filename)) as f:
+            # Split off the namespace and file extension, leaving just the type.
+            type_path = '.'.join(filename.split('.')[1:-1])
+            self._custom_dart[type_path] = f.read()
+
+  def Generate(self):
+    """Generates a Code object with the .dart for the entire namespace.
+    """
+    c = Code()
+    (c.Append(LICENSE)
+      .Append()
+      .Append('part of chrome;'))
+
+    if self._types:
+      (c.Append()
+        .Append('/**')
+        .Append(' * Types')
+        .Append(' */')
+      )
+    for type_name in self._types:
+      c.Concat(self._GenerateType(self._types[type_name]))
+
+    if self._namespace.events:
+      (c.Append()
+        .Append('/**')
+        .Append(' * Events')
+        .Append(' */')
+      )
+    for event_name in self._namespace.events:
+      c.Concat(self._GenerateEvent(self._namespace.events[event_name]))
+
+    (c.Append()
+      .Append('/**')
+      .Append(' * Functions')
+      .Append(' */')
+    )
+    c.Concat(self._GenerateMainClass())
+
+    return c
+
+  def _GenerateType(self, type_):
+    """Given a Type object, returns the Code with the .dart for this
+    type's definition.
+
+    Assumes this type is a Parameter Type (creatable by user), and creates an
+    object that extends ChromeObject. All parameters are specifiable as named
+    arguments in the constructor, and all methods are wrapped with getters and
+    setters that hide the JS() implementation.
+    """
+    c = Code()
+    (c.Append()
+      .Concat(self._GenerateDocumentation(type_))
+      .Sblock('class %(type_name)s extends ChromeObject {')
+    )
+
+    # Check whether this type has function members. If it does, don't allow
+    # public construction.
+    for p in type_.properties.values():
+      print p.name, self._IsFunction(p)
+    add_public_constructor = all(not self._IsFunction(p)
+                                 for p in type_.properties.values())
+    constructor_fields = [self._GeneratePropertySignature(p)
+                          for p in type_.properties.values()]
+
+    if add_public_constructor:
+      (c.Append('/*')
+        .Append(' * Public constructor')
+        .Append(' */')
+        .Sblock('%(type_name)s({%(constructor_fields)s}) {')
+      )
+
+      for prop_name in type_.properties:
+        c.Append('this.%s = %s;' % (prop_name, prop_name))
+      (c.Eblock('}')
+        .Append()
+      )
+
+    (c.Append('/*')
+      .Append(' * Private constructor')
+      .Append(' */')
+      .Append('%(type_name)s._proxy(_jsObject) : super._proxy(_jsObject);')
+    )
+
+    # Add an accessor (getter & setter) for each property.
+    properties = [p for p in type_.properties.values()
+                  if not self._IsFunction(p)]
+    if properties:
+      (c.Append()
+        .Append('/*')
+        .Append(' * Public accessors')
+        .Append(' */')
+      )
+    for prop in properties:
+      type_name = self._GetPropertyType(prop)
+      prop_is_base_type = self._IsBaseType(prop)
+
+      # Check for custom dart for this whole property.
+      if not self._TryAppendOverride(c, type_, prop, add_doc=True):
+        # Add the getter.
+        if not self._TryAppendOverride(c, type_, prop, '.get', add_doc=True):

[not at google - send to devlin, 2013/01/31 02:08:48]

key_suffix='.get'

[sashab, 2013/01/31 04:41:40]

Done.

+          # Add the documentation for this property.
+          (c.Append()
+            .Concat(self._GenerateDocumentation(prop))
+          )
+
+          # TODO(sashab): Serialize generic Dart objects differently.
+          if prop_is_base_type or self._IsObjectType(prop):
+            c.Append("%s get %s => JS('%s', '#.%s', this._jsObject);" %
+                (type_name, prop.name, type_name, prop.name))
+          elif prop.type_.property_type == PropertyType.REF:
+            c.Append("%s get %s => new %s._proxy(JS('', '#.%s', "
+                     "this._jsObject));"
+              % (type_name, prop.name, type_name, prop.name))
+          else:
+            raise Exception(
+                "Could not generate wrapper for %s.%s: unserializable type %s" %
+                (type_.name, prop.name, type_name)
+            )
+
+        # Add the setter.
+        if not self._TryAppendOverride(c, type_, prop, '.set'):

[not at google - send to devlin, 2013/01/31 02:08:48]

key_suffix='.set'

[sashab, 2013/01/31 04:41:40]

Done.

+          wrapped_name = prop.name
+          if not prop_is_base_type:
+            wrapped_name = 'convertArgument(%s)' % prop.name
+
+          (c.Append()
+            .Sblock("void set %s(%s %s) {" % (prop.name, type_name, prop.name))
+            .Append("JS('void', '#.%s = #', this._jsObject, %s);" %
+              (prop.name, wrapped_name))
+            .Eblock("}")
+          )
+
+    # Now add all the methods.
+    methods = [t for t in type_.properties.values()
+               if self._IsFunction(t)]

[not at google - send to devlin, 2013/01/31 02:08:48]

might fit on 1 line?

[sashab, 2013/01/31 04:41:40]

Done.

+    if methods:
+      (c.Append()
+        .Append('/*')
+        .Append(' * Methods')
+        .Append(' */')
+      )
+    for prop in methods:
+      c.Concat(self._GenerateFunction(prop.type_.function))
+
+    (c.Eblock('}')
+      .Substitute({
+        'type_name': type_.simple_name,
+        'constructor_fields': ', '.join(constructor_fields)
+      })
+    )
+
+    return c
+
+  def _GenerateDocumentation(self, prop):
+    """Given an object, generates the documentation for this object (as a
+    code string) and returns the Code object.
+
+    Returns an empty code object if the object has no documentation.
+
+    Uses triple-quotes for the string.
+    """
+    c = Code()
+    if prop.description is not None:
+      for line in prop.description.split('\n'):
+        c.Comment(line, comment_prefix='/// ')
+    return c
+
+
+  def _GenerateFunction(self, f):
+    """Returns the Code object for the given function.
+    """
+    c = Code()
+    (c.Append()
+      .Concat(self._GenerateDocumentation(f))
+    )
+
+    if not self._NeedsProxiedCallback(f):
+        c.Append("%s => %s;" % (self._GenerateFunctionSignature(f),
+                               self._GenerateProxyCall(f)))
+        return c
+
+    c.Sblock("%s {" % self._GenerateFunctionSignature(f))
+
+    # Define the proxied callback.
+    proxied_params = []
+    for p in f.callback.params:
+      if self._IsBaseType(p):
+        proxied_params.append(p.name)
+      elif self._IsObjectType(p):
+        proxied_params.append("new %s._proxy(%s)" % (
+            self._GetPropertyType(p), p.name))
+      else:
+        raise Exception(
+            "Cannot automatically create proxy; can't wrap %s.%s, type %s" % (
+                f.name, p.name, p.type_.name))
+
+    (c.Sblock("void __proxy_callback(%s) {" % ', '.join(p.name for p in
+                                               f.callback.params))
+      .Sblock("if (?%s)" % f.callback.name)
+      .Append("%s(%s);" % (f.callback.name, ', '.join(proxied_params)))
+      .Eblock(None)

[not at google - send to devlin, 2013/01/31 02:08:48]

like I said earlier, just make None the default? The only thing this would
affect is 2 places in h_generator.py, and you could update those to add an extra
Append().

[sashab, 2013/01/31 04:41:40]

Done.

+      .Eblock("}")
+      .Append("%s;" % self._GenerateProxyCall(f))
+      .Eblock("}")
+    )
+    return c
+
+  def _NeedsProxiedCallback(self, f):
+    """Given a function, returns True if this function's callback needs to be
+    proxied, False if not.
+
+    Function callbacks need to be proxied if they have at least one
+    non-base-type parameter.
+    """
+    return f.callback and any(
+        not self._IsBaseType(p) for p in f.callback.params)
+
+  def _GenerateProxyCall(self, function, call_target='this._jsObject'):
+    """Given a function, generates the code to call that function via JS().
+    Returns a string.
+
+    |call_target| is the name of the object to call the function on. The default
+    is this._jsObject.
+
+    e.g.
+        JS('void', '#.resizeTo(#, #)', this._jsObject, width, height)
+        JS('void', '#.setBounds(#)', this._jsObject, convertArgument(bounds))
+    """
+    n_params = len(function.params)
+    if function.callback:
+      n_params += 1
+
+    params = ["'%s'" % self._GetPropertyType(function.returns),
+              "'#.%s(%s)'" % (function.name,
+                              ', '.join(['#'] * n_params)),
+              call_target]
+
+    for param in function.params:
+      if not self._IsBaseType(param):
+        params.append('convertArgument(%s)' % param.name)
+      else:
+        params.append(param.name)
+    if function.callback:
+      # If this isn't a base type, we need a proxied callback.
+      callback_name = function.callback.name
+      if self._NeedsProxiedCallback(function):
+        callback_name = "__proxy_callback"
+      params.append('convertDartClosureToJS(%s, %s)' % (callback_name,
+                    len(function.callback.params)))
+
+    return 'JS(%s)' % ', '.join(params)
+
+  def _GenerateEvent(self, event):
+    """Given a Function object, returns the Code with the .dart for this event,
+    represented by the function.
+
+    All events extend the Event base type.
+    """
+    c = Code()
+
+    # Add documentation for this event.
+    (c.Append()
+      .Concat(self._GenerateDocumentation(event))
+      .Sblock('class Event_%(event_name)s extends Event {')
+    )
+
+    # Override Event callback type definitions.
+    for ret_type, event_func in (('void', 'addListener'),
+                                 ('void', 'removeListener'),
+                                 ('bool', 'hasListener')):
+
+      param_list = self._GenerateParameterList(event.params, event.callback,
+                                               allow_optional = False)
+
+      c.Append('%s %s(void callback(%s)) => super.%s(callback);' %
+          (ret_type, event_func, param_list, event_func))
+
+    # Generate the constructor.
+    (c.Append()
+      .Append('Event_%(event_name)s(jsObject) : '
+              'super(jsObject, %(param_num)d);')
+    )
+
+    (c.Eblock('}')
+      .Substitute({
+        'event_name': self._namespace.unix_name + '_' + event.name,
+        'param_num': len(event.params)
+      })
+    )
+
+    return c
+
+  def _GenerateMainClass(self):
+    """Generates the main class for this file, which links to all functions
+    and events.
+
+    Returns a code object.
+    """
+    c = Code()
+    (c.Append()
+      .Sblock('class API_%s {' % self._namespace.unix_name)
+      .Append('/*')
+      .Append(' * API connection')
+      .Append(' */')
+      .Append('Object _jsObject;')
+    )
+
+    # Add events.
+    if self._namespace.events:
+      (c.Append()
+        .Append('/*')
+        .Append(' * Events')
+        .Append(' */')
+      )
+    for event_name in self._namespace.events:
+      c.Append('Event_%s_%s %s;' % (self._namespace.unix_name, event_name,
+                                    event_name))
+
+    # Add functions.
+    if self._namespace.functions:
+      (c.Append()
+        .Append('/*')
+        .Append(' * Functions')
+        .Append(' */')
+      )
+    for function in self._namespace.functions.values():
+      c.Concat(self._GenerateFunction(function))
+
+    # Add the constructor.
+    (c.Append()
+      .Sblock('API_%s(this._jsObject) {' % self._namespace.unix_name)
+    )
+
+    # Add events to constructor.
+    for event_name in self._namespace.events:
+      c.Append("%s = new Event_%s_%s(JS('', '#.%s', this._jsObject));" %
+        (event_name, self._namespace.unix_name, event_name, event_name))
+
+      (c.Eblock('}')
+      .Eblock('}')
+    )
+    return c
+
+  def _GeneratePropertySignature(self, prop):
+    """Given a property, returns a signature for that property.
+    Recursively generates the signature for callbacks.
+    Returns a String for the given property.
+
+    e.g.
+      bool x
+      void onClosed()
+      void doSomething(bool x, void callback([String x]))
+    """
+    if self._IsFunction(prop):
+      return self._GenerateFunctionSignature(prop.type_.function)
+    return '%(type)s %(name)s' % {
+               'type': self._GetPropertyType(prop),
+               'name': prop.simple_name
+           }
+
+  def _GenerateFunctionSignature(self, function):
+    """Given a function object, returns the signature for that function.
+    Recursively generates the signature for callbacks.
+    Returns a String for the given function.
+
+    If prepend_this is True, adds "this." to the function's name.
+
+    e.g.
+      void onClosed()
+      bool isOpen([String type])
+      void doSomething(bool x, void callback([String x]))
+
+    e.g. If prepend_this is True:
+      void this.onClosed()
+      bool this.isOpen([String type])
+      void this.doSomething(bool x, void callback([String x]))
+    """
+    sig = '%(return_type)s %(name)s(%(params)s)'
+
+    if function.returns:
+      return_type = self._GetPropertyType(function.returns)
+    else:
+      return_type = 'void'
+
+    return sig % {
+        'return_type': return_type,
+        'name': function.simple_name,
+        'params': self._GenerateParameterList(function.params,
+                                              function.callback)
+    }
+
+  def _GenerateParameterList(self, params, callback=None,
+                             allow_optional=True):

[not at google - send to devlin, 2013/01/31 02:08:48]

if it can't fit on 1 line then align parameters vertically

[sashab, 2013/01/31 04:41:40]

Done.

+    """Given a list of function parameters, generates their signature (as a
+    string).
+
+    e.g.
+      [String type]
+      bool x, void callback([String x])
+
+    If allow_optional is False, ignores optional parameters. Useful for
+    callbacks, where optional parameters are not used.
+    """
+    # Params lists (required & optional), to be joined with ,'s.

[not at google - send to devlin, 2013/01/31 02:08:48]

commas?

[sashab, 2013/01/31 04:41:40]

Done.

+    # FIXME(sashab): assuming all optional params come after required ones

[not at google - send to devlin, 2013/01/31 02:08:48]

I can't parse this sentence. Should it be like "Don't assume all optional
parameters come after required ones"?

[sashab, 2013/01/31 04:41:40]

Haha, yes, you're right. Fixed

+    params_req = []
+    params_opt = []
+    for param in params:
+      p_sig = self._GeneratePropertySignature(param)
+      if allow_optional and param.optional:
+        params_opt.append(p_sig)
+      else:
+        params_req.append(p_sig)

[not at google - send to devlin, 2013/01/31 02:08:48]

this isn't ignoring optional parameters, it's making them required? Either code
or comment needs to change?

[sashab, 2013/01/31 04:41:40]

Sorry, comment changed. And I also changed the name of the argument to
"convert_optional", and reversed its usage (False-->True).

+
+    # Add the callback, if it exists.
+    if callback:
+      c_sig = self._GenerateFunctionSignature(callback)
+      if callback.optional:
+        params_opt.append(c_sig)
+      else:
+        params_req.append(c_sig)
+
+    # Join the parameters, wrapping the optional params in square brackets.
+    if params_opt:
+      params_opt[0] = '[%s' % params_opt[0]
+      params_opt[-1] = '%s]' % params_opt[-1]

[not at google - send to devlin, 2013/01/31 02:08:48]

a bit bizarre but much better, and I can't think of a non-bizarre way to do it.
Please add to comment what you put in the code review comment though.

[sashab, 2013/01/31 04:41:40]

Done. Or should this rather be in the function signature's comment?

[not at google - send to devlin, 2013/02/02 00:45:47]

What you have is good.

+    param_sets = [', '.join(params_req),
+                  ', '.join(params_opt)]

[not at google - send to devlin, 2013/01/31 02:08:48]

single line

[sashab, 2013/01/31 04:41:40]

Done.

+
+    return ', '.join(p for p in param_sets if p)

[not at google - send to devlin, 2013/01/31 02:08:48]

why the "if p"? I.e. why can't it be ', '.join(param_sets)?

[sashab, 2013/01/31 04:41:40]

This is part of the bizarre logic. If there are no optional parameters, this
prevents a trailing comma, ie '(x, y,)'. Similarly, if there are no required
parameters, this prevents a leading comma, ie '(, [a, b])'.

Put this in the comment too.

+
+  def _TryAppendOverride(self, c, type_, prop, key_suffix='', add_doc=False):

[not at google - send to devlin, 2013/01/31 02:08:48]

TryAppendOverride is a bit of an awkward name. Perhaps ConcatOverride or
something.

[sashab, 2013/01/31 04:41:40]

It returns True if it appended the override, False if not, hence the "Try".

Renamed it to ConcatOverride for now.

+    """Given a particular type and property to find in the custom dart
+    overrides, checks whether there is an override for that key.
+    If there is, adds a newline, appends the override code, and returns True.

[not at google - send to devlin, 2013/01/31 02:08:48]

"adds a newline" -> doesn't seem like this should be the job of this method.

[sashab, 2013/01/31 04:41:40]

Ok, the reason this is needed is in case the override is blank.

If the override is blank ('nodart' equivalent), we don't want to add a newline
at all. But we don't know whether the override is blank until we reach this
method.

If I move the logic for adding the newline to _outside_ this method, it will add
newlines for 'nodart'ed methods, too.

I originally had a "_HasOverride()" method, and a lot of this logic was in the
calling function. But they you had to call "_ApplyOverride()" with the same
arguments, which meant re-passing the key and stuff, and it didn't feel right.

Can you think of a better way I could structure it?

+    If not, returns False.
+
+    |key_suffix| will be added to the end of the key before searching, e.g.
+    '.set' or '.get' can be used for setters and getters respectively.
+
+    If add_doc is given, adds the documentation for this property before the
+    override code.
+    If the override code is empty, does nothing (and does not add
+    documentation), but returns True (treats it as a valid override).
+    """
+    contents = self._custom_dart.get('%s.%s%s' % (type_.name, prop.name,
+                                     key_suffix))
+    if contents is None:
+      return False
+

[not at google - send to devlin, 2013/01/31 02:08:48]

maybe early-exit here too, if it's empty:

if contents.strip() == '':
  # Passing in an empty file here is the idiom for disabling
  # compilation of a function for dart.
  return Code()

if prop is not None:
  c.Concat(self._GenreateDocumentation(prop))
...

[sashab, 2013/01/31 04:41:40]

Good idea! :D

+    if contents.strip():
+      if prop is not None:

[not at google - send to devlin, 2013/01/31 02:08:48]

although TBH I find this idiom a bit strange. People will see these files
checked in empty and will be like "what", or they might say "/// Left empty to
disable blah" -- and I think the comment thing is what we might want to support.
So something to think about.

[sashab, 2013/01/31 04:41:40]

It's a little tough, because its unclear: does putting a comment in one of the
files mean you _want_ it copied into the final library, or not? The libraries
are public-facing, so its important.

benwells did suggest an @nodoc flag which you can put at the top of the file,
which overrides the default and doesn't show the documentation for a property.
Maybe after the flag you could put more stuff you don't want to appear, e.g.:

app.window.AppWindow.dart:
  @nodoc Disabled because an AppWindow is secret.

app.window.Intent.dart:
  @nodoc The docs online are old, use the ones below instead.
  /// blah blah
  function() { blah }

So blank files would now keep the documentation, and you would need "@nodoc" to
actually remove them. Now a file with "@nodoc" is closer to the equivalent of
[nodart].

What do you think?

+        (c.Append()
+          .Concat(self._GenerateDocumentation(prop))
+        )
+      else:
+        c.Append()

[not at google - send to devlin, 2013/01/31 02:08:48]

seem to be always appending here, so pull out above the "if prop is not None" -
however, it seems like the extra newline is something that callers should handle

[sashab, 2013/01/31 04:41:40]

Thanks, fixed this one; see comment above about callers.

+    for line in contents.split('\n'):
+      c.Append(line)
+    return True
+
+  def _IsFunction(self, prop):
+    """Given a model.Property, returns whether this type is a function.
+    """
+    return prop.type_.property_type == PropertyType.FUNCTION
+
+  def _IsObjectType(self, prop):
+    """Given a model.Property, returns whether this type is an object.
+    """
+    return prop.type_.property_type in [PropertyType.OBJECT, PropertyType.ANY]
+
+  def _IsBaseType(self, prop):
+    """Given a model.Property, returns whether this type is a base type
+    (string, number or boolean).
+    """
+    return (self._GetPropertyType(prop) in
+            ['bool', 'num', 'int', 'double', 'String'])
+
+  def _GetPropertyType(self, prop, container_type=False):

[not at google - send to devlin, 2013/01/31 02:08:48]

call this _GetDartType and pass in the type rather than the property. Callers
can decide whether to pass in prop.type or prop.type.item_type (no need for
container_type).

[sashab, 2013/01/31 04:41:40]

Yup, was going to do this before. Made a wrapper _GetPropertyType in case prop
is null.

+    """Given a model.Property object, returns its type as a Dart string.
+
+    If container_type is True, returns the type of the objects prop is
+    containing, rather than the type of prop itself.
+    """
+    if prop is None:
+      return 'void'
+
+    if container_type:
+      type_ = prop.type_.item_type
+    else:
+      type_ = prop.type_
+    prop_type = type_.property_type
+
+    if prop_type is None:
+      return 'void'
+    elif prop_type is PropertyType.REF:
+      if GetNamespace(type_.ref_type) == self._namespace.name:
+        # This type is in this namespace; just use its base name.
+        return GetBaseNamespace(type_.ref_type)
+      else:
+        # TODO(sashab): Work out how to import this foreign type.
+        return type_.ref_type
+    elif prop_type is PropertyType.BOOLEAN:
+      return 'bool'
+    elif prop_type is PropertyType.INTEGER:
+      return 'int'
+    elif prop_type is PropertyType.INT64:
+      return 'num'
+    elif prop_type is PropertyType.DOUBLE:
+      return 'double'
+    elif prop_type is PropertyType.STRING:
+      return 'String'
+    elif prop_type is PropertyType.ENUM:
+      return 'String'
+    elif prop_type is PropertyType.CHOICES:
+      # TODO: What is a Choices type? Is it closer to a Map Dart object?
+      return 'Object'

[not at google - send to devlin, 2013/01/31 02:08:48]

I wrote a long thing in response to what you said, but it occurs to me that you
could also go the JS-esque route (if that's possible) and just make this
untyped.

[sashab, 2013/01/31 04:41:40]

'Object' is the equivalent of untyped. See other comment.

+    elif prop_type is PropertyType.ANY:
+      return 'Object'
+    elif prop_type is PropertyType.OBJECT:
+      # TODO(sashab): Work out a mapped type name.
+      return type_.instance_of or 'Object'
+    elif prop_type is PropertyType.FUNCTION:
+      return 'Function'
+    elif prop_type is PropertyType.ARRAY:
+      if type_.item_type:

[not at google - send to devlin, 2013/01/31 02:08:48]

there should always be a list type, this check should be unnecessary?

[sashab, 2013/01/31 04:41:40]

After investigating, you're right - its invalid IDL when there's no type
defined. Fixed.

+        return 'List<%s>' % self._GetPropertyType(prop, container_type=True)
+      else:
+        return 'List'
+    elif prop_type is PropertyType.BINARY:
+      return 'String'
+    else:
+      raise NotImplementedError(prop_type)
+