tools/json_schema_compiler/cc_generator.py

   1 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 from code import Code
   6 from model import PropertyType
   7 import cpp_util
   8 import schema_util
   9 import util_cc_helper
  10
  11 class CCGenerator(object):
  12   def __init__(self, type_generator, cpp_namespace):
  13     self._type_generator = type_generator
  14     self._cpp_namespace = cpp_namespace
  15
  16   def Generate(self, namespace):
  17     return _Generator(namespace,
  18                       self._type_generator,
  19                       self._cpp_namespace).Generate()
  20
  21
  22 class _Generator(object):
  23   """A .cc generator for a namespace.
  24   """
  25   def __init__(self, namespace, cpp_type_generator, cpp_namespace):
  26     self._namespace = namespace
  27     self._type_helper = cpp_type_generator
  28     self._cpp_namespace = cpp_namespace
  29     self._target_namespace = (
  30         self._type_helper.GetCppNamespaceName(self._namespace))
  31     self._util_cc_helper = (
  32         util_cc_helper.UtilCCHelper(self._type_helper))
  33     self._generate_error_messages = namespace.compiler_options.get(
  34         'generate_error_messages', False)
  35
  36   def Generate(self):
  37     """Generates a Code object with the .cc for a single namespace.
  38     """
  39     c = Code()
  40     (c.Append(cpp_util.CHROMIUM_LICENSE)
  41       .Append()
  42       .Append(cpp_util.GENERATED_FILE_MESSAGE % self._namespace.source_file)
  43       .Append()
  44       .Append(self._util_cc_helper.GetIncludePath())
  45       .Append('#include "base/logging.h"')
  46       .Append('#include "base/strings/string_number_conversions.h"')
  47       .Append('#include "base/strings/utf_string_conversions.h"')
  48       .Append('#include "%s/%s.h"' %
  49           (self._namespace.source_file_dir, self._namespace.unix_name))
  50       .Cblock(self._type_helper.GenerateIncludes(include_soft=True))
  51       .Append()
  52       .Concat(cpp_util.OpenNamespace(self._cpp_namespace))
  53       .Cblock(self._type_helper.GetNamespaceStart())
  54     )
  55     if self._namespace.properties:
  56       (c.Append('//')
  57         .Append('// Properties')
  58         .Append('//')
  59         .Append()
  60       )
  61       for property in self._namespace.properties.values():
  62         property_code = self._type_helper.GeneratePropertyValues(
  63             property,
  64             'const %(type)s %(name)s = %(value)s;',
  65             nodoc=True)
  66         if property_code:
  67           c.Cblock(property_code)
  68     if self._namespace.types:
  69       (c.Append('//')
  70         .Append('// Types')
  71         .Append('//')
  72         .Append()
  73         .Cblock(self._GenerateTypes(None, self._namespace.types.values()))
  74       )
  75     if self._namespace.functions:
  76       (c.Append('//')
  77         .Append('// Functions')
  78         .Append('//')
  79         .Append()
  80       )
  81     for function in self._namespace.functions.values():
  82       c.Cblock(self._GenerateFunction(function))
  83     if self._namespace.events:
  84       (c.Append('//')
  85         .Append('// Events')
  86         .Append('//')
  87         .Append()
  88       )
  89       for event in self._namespace.events.values():
  90         c.Cblock(self._GenerateEvent(event))
  91     (c.Concat(self._type_helper.GetNamespaceEnd())
  92       .Cblock(cpp_util.CloseNamespace(self._cpp_namespace))
  93     )
  94     return c
  95
  96   def _GenerateType(self, cpp_namespace, type_):
  97     """Generates the function definitions for a type.
  98     """
  99     classname = cpp_util.Classname(schema_util.StripNamespace(type_.name))
 100     c = Code()
 101
 102     if type_.functions:
 103       # Wrap functions within types in the type's namespace.
 104       (c.Append('namespace %s {' % classname)
 105         .Append())
 106       for function in type_.functions.values():
 107         c.Cblock(self._GenerateFunction(function))
 108       c.Append('}  // namespace %s' % classname)
 109     elif type_.property_type == PropertyType.ARRAY:
 110       c.Cblock(self._GenerateType(cpp_namespace, type_.item_type))
 111     elif type_.property_type in (PropertyType.CHOICES,
 112                                  PropertyType.OBJECT):
 113       if cpp_namespace is None:
 114         classname_in_namespace = classname
 115       else:
 116         classname_in_namespace = '%s::%s' % (cpp_namespace, classname)
 117
 118       if type_.property_type == PropertyType.OBJECT:
 119         c.Cblock(self._GeneratePropertyFunctions(classname_in_namespace,
 120                                                  type_.properties.values()))
 121       else:
 122         c.Cblock(self._GenerateTypes(classname_in_namespace, type_.choices))
 123
 124       (c.Append('%s::%s()' % (classname_in_namespace, classname))
 125         .Cblock(self._GenerateInitializersAndBody(type_))
 126         .Append('%s::~%s() {}' % (classname_in_namespace, classname))
 127         .Append()
 128       )
 129       if type_.origin.from_json:
 130         c.Cblock(self._GenerateTypePopulate(classname_in_namespace, type_))
 131         if cpp_namespace is None:  # only generate for top-level types
 132           c.Cblock(self._GenerateTypeFromValue(classname_in_namespace, type_))
 133       if type_.origin.from_client:
 134         c.Cblock(self._GenerateTypeToValue(classname_in_namespace, type_))
 135     elif type_.property_type == PropertyType.ENUM:
 136       (c.Cblock(self._GenerateEnumToString(cpp_namespace, type_))
 137         .Cblock(self._GenerateEnumFromString(cpp_namespace, type_))
 138       )
 139
 140     return c
 141
 142   def _GenerateInitializersAndBody(self, type_):
 143     items = []
 144     for prop in type_.properties.values():
 145       if prop.optional:
 146         continue
 147
 148       t = prop.type_
 149       if t.property_type == PropertyType.INTEGER:
 150         items.append('%s(0)' % prop.unix_name)
 151       elif t.property_type == PropertyType.DOUBLE:
 152         items.append('%s(0.0)' % prop.unix_name)
 153       elif t.property_type == PropertyType.BOOLEAN:
 154         items.append('%s(false)' % prop.unix_name)
 155       elif (t.property_type == PropertyType.ANY or
 156             t.property_type == PropertyType.ARRAY or
 157             t.property_type == PropertyType.BINARY or  # mapped to std::string
 158             t.property_type == PropertyType.CHOICES or
 159             t.property_type == PropertyType.ENUM or
 160             t.property_type == PropertyType.OBJECT or
 161             t.property_type == PropertyType.FUNCTION or
 162             t.property_type == PropertyType.REF or
 163             t.property_type == PropertyType.STRING):
 164         # TODO(miket): It would be nice to initialize CHOICES and ENUM, but we
 165         # don't presently have the semantics to indicate which one of a set
 166         # should be the default.
 167         continue
 168       else:
 169         raise TypeError(t)
 170
 171     if items:
 172       s = ': %s' % (', '.join(items))
 173     else:
 174       s = ''
 175     s = s + ' {}'
 176     return Code().Append(s)
 177
 178   def _GenerateTypePopulate(self, cpp_namespace, type_):
 179     """Generates the function for populating a type given a pointer to it.
 180
 181     E.g for type "Foo", generates Foo::Populate()
 182     """
 183     classname = cpp_util.Classname(schema_util.StripNamespace(type_.name))
 184     c = Code()
 185     (c.Append('// static')
 186       .Append('bool %(namespace)s::Populate(')
 187       .Sblock('    %s) {' % self._GenerateParams(
 188           ('const base::Value& value', '%(name)s* out'))))
 189
 190     if type_.property_type == PropertyType.CHOICES:
 191       for choice in type_.choices:
 192         (c.Sblock('if (%s) {' % self._GenerateValueIsTypeExpression('value',
 193                                                                     choice))
 194             .Concat(self._GeneratePopulateVariableFromValue(
 195                 choice,
 196                 '(&value)',
 197                 'out->as_%s' % choice.unix_name,
 198                 'false',
 199                 is_ptr=True))
 200             .Append('return true;')
 201           .Eblock('}')
 202         )
 203       (c.Concat(self._GenerateError(
 204           '"expected %s, got " +  %s' %
 205               (" or ".join(choice.name for choice in type_.choices),
 206               self._util_cc_helper.GetValueTypeString('value'))))
 207         .Append('return false;'))
 208     elif type_.property_type == PropertyType.OBJECT:
 209       (c.Sblock('if (!value.IsType(base::Value::TYPE_DICTIONARY)) {')
 210         .Concat(self._GenerateError(
 211           '"expected dictionary, got " + ' +
 212           self._util_cc_helper.GetValueTypeString('value')))
 213         .Append('return false;')
 214         .Eblock('}'))
 215
 216       if type_.properties or type_.additional_properties is not None:
 217         c.Append('const base::DictionaryValue* dict = '
 218                      'static_cast<const base::DictionaryValue*>(&value);')
 219       for prop in type_.properties.values():
 220         c.Concat(self._InitializePropertyToDefault(prop, 'out'))
 221       for prop in type_.properties.values():
 222         c.Concat(self._GenerateTypePopulateProperty(prop, 'dict', 'out'))
 223       if type_.additional_properties is not None:
 224         if type_.additional_properties.property_type == PropertyType.ANY:
 225           c.Append('out->additional_properties.MergeDictionary(dict);')
 226         else:
 227           cpp_type = self._type_helper.GetCppType(type_.additional_properties,
 228                                                   is_in_container=True)
 229           (c.Append('for (base::DictionaryValue::Iterator it(*dict);')
 230             .Sblock('     !it.IsAtEnd(); it.Advance()) {')
 231               .Append('%s tmp;' % cpp_type)
 232               .Concat(self._GeneratePopulateVariableFromValue(
 233                   type_.additional_properties,
 234                   '(&it.value())',
 235                   'tmp',
 236                   'false'))
 237               .Append('out->additional_properties[it.key()] = tmp;')
 238             .Eblock('}')
 239           )
 240       c.Append('return true;')
 241     (c.Eblock('}')
 242       .Substitute({'namespace': cpp_namespace, 'name': classname}))
 243     return c
 244
 245   def _GenerateValueIsTypeExpression(self, var, type_):
 246     real_type = self._type_helper.FollowRef(type_)
 247     if real_type.property_type is PropertyType.CHOICES:
 248       return '(%s)' % ' || '.join(self._GenerateValueIsTypeExpression(var,
 249                                                                       choice)
 250                                   for choice in real_type.choices)
 251     return '%s.IsType(%s)' % (var, cpp_util.GetValueType(real_type))
 252
 253   def _GenerateTypePopulateProperty(self, prop, src, dst):
 254     """Generate the code to populate a single property in a type.
 255
 256     src: base::DictionaryValue*
 257     dst: Type*
 258     """
 259     c = Code()
 260     value_var = prop.unix_name + '_value'
 261     c.Append('const base::Value* %(value_var)s = NULL;')
 262     if prop.optional:
 263       (c.Sblock(
 264           'if (%(src)s->GetWithoutPathExpansion("%(key)s", &%(value_var)s)) {')
 265         .Concat(self._GeneratePopulatePropertyFromValue(
 266             prop, value_var, dst, 'false')))
 267       underlying_type = self._type_helper.FollowRef(prop.type_)
 268       if underlying_type.property_type == PropertyType.ENUM:
 269         (c.Append('} else {')
 270           .Append('%%(dst)s->%%(name)s = %s;' %
 271               self._type_helper.GetEnumNoneValue(prop.type_)))
 272       c.Eblock('}')
 273     else:
 274       (c.Sblock(
 275           'if (!%(src)s->GetWithoutPathExpansion("%(key)s", &%(value_var)s)) {')
 276         .Concat(self._GenerateError('"\'%%(key)s\' is required"'))
 277         .Append('return false;')
 278         .Eblock('}')
 279         .Concat(self._GeneratePopulatePropertyFromValue(
 280             prop, value_var, dst, 'false'))
 281       )
 282     c.Append()
 283     c.Substitute({
 284       'value_var': value_var,
 285       'key': prop.name,
 286       'src': src,
 287       'dst': dst,
 288       'name': prop.unix_name
 289     })
 290     return c
 291
 292   def _GenerateTypeFromValue(self, cpp_namespace, type_):
 293     classname = cpp_util.Classname(schema_util.StripNamespace(type_.name))
 294     c = Code()
 295     (c.Append('// static')
 296       .Append('scoped_ptr<%s> %s::FromValue(%s) {' % (classname,
 297         cpp_namespace, self._GenerateParams(('const base::Value& value',))))
 298       .Append('  scoped_ptr<%s> out(new %s());' % (classname, classname))
 299       .Append('  if (!Populate(%s))' % self._GenerateArgs(
 300           ('value', 'out.get()')))
 301       .Append('    return scoped_ptr<%s>();' % classname)
 302       .Append('  return out.Pass();')
 303       .Append('}')
 304     )
 305     return c
 306
 307   def _GenerateTypeToValue(self, cpp_namespace, type_):
 308     """Generates a function that serializes the type into a base::Value.
 309     E.g. for type "Foo" generates Foo::ToValue()
 310     """
 311     if type_.property_type == PropertyType.OBJECT:
 312       return self._GenerateObjectTypeToValue(cpp_namespace, type_)
 313     elif type_.property_type == PropertyType.CHOICES:
 314       return self._GenerateChoiceTypeToValue(cpp_namespace, type_)
 315     else:
 316       raise ValueError("Unsupported property type %s" % type_.type_)
 317
 318   def _GenerateObjectTypeToValue(self, cpp_namespace, type_):
 319     """Generates a function that serializes an object-representing type
 320     into a base::DictionaryValue.
 321     """
 322     c = Code()
 323     (c.Sblock('scoped_ptr<base::DictionaryValue> %s::ToValue() const {' %
 324           cpp_namespace)
 325         .Append('scoped_ptr<base::DictionaryValue> value('
 326                     'new base::DictionaryValue());')
 327         .Append()
 328     )
 329
 330     for prop in type_.properties.values():
 331       if prop.optional:
 332         # Optional enum values are generated with a NONE enum value.
 333         underlying_type = self._type_helper.FollowRef(prop.type_)
 334         if underlying_type.property_type == PropertyType.ENUM:
 335           c.Sblock('if (%s != %s) {' %
 336               (prop.unix_name,
 337                self._type_helper.GetEnumNoneValue(prop.type_)))
 338         else:
 339           c.Sblock('if (%s.get()) {' % prop.unix_name)
 340
 341       # ANY is a base::Value which is abstract and cannot be a direct member, so
 342       # it will always be a pointer.
 343       is_ptr = prop.optional or prop.type_.property_type == PropertyType.ANY
 344       c.Append('value->SetWithoutPathExpansion("%s", %s);' % (
 345           prop.name,
 346           self._CreateValueFromType(prop.type_,
 347                                     'this->%s' % prop.unix_name,
 348                                     is_ptr=is_ptr)))
 349
 350       if prop.optional:
 351         c.Eblock('}')
 352
 353     if type_.additional_properties is not None:
 354       if type_.additional_properties.property_type == PropertyType.ANY:
 355         c.Append('value->MergeDictionary(&additional_properties);')
 356       else:
 357         # Non-copyable types will be wrapped in a linked_ptr for inclusion in
 358         # maps, so we need to unwrap them.
 359         needs_unwrap = (
 360             not self._type_helper.IsCopyable(type_.additional_properties))
 361         cpp_type = self._type_helper.GetCppType(type_.additional_properties,
 362                                                 is_in_container=True)
 363         (c.Sblock('for (std::map<std::string, %s>::const_iterator it =' %
 364                       cpp_util.PadForGenerics(cpp_type))
 365           .Append('       additional_properties.begin();')
 366           .Append('   it != additional_properties.end(); ++it) {')
 367           .Append('value->SetWithoutPathExpansion(it->first, %s);' %
 368               self._CreateValueFromType(
 369                   type_.additional_properties,
 370                   '%sit->second' % ('*' if needs_unwrap else '')))
 371           .Eblock('}')
 372         )
 373
 374     return (c.Append()
 375              .Append('return value.Pass();')
 376            .Eblock('}'))
 377
 378   def _GenerateChoiceTypeToValue(self, cpp_namespace, type_):
 379     """Generates a function that serializes a choice-representing type
 380     into a base::Value.
 381     """
 382     c = Code()
 383     c.Sblock('scoped_ptr<base::Value> %s::ToValue() const {' % cpp_namespace)
 384     c.Append('scoped_ptr<base::Value> result;')
 385     for choice in type_.choices:
 386       choice_var = 'as_%s' % choice.unix_name
 387       (c.Sblock('if (%s) {' % choice_var)
 388           .Append('DCHECK(!result) << "Cannot set multiple choices for %s";' %
 389                       type_.unix_name)
 390           .Append('result.reset(%s);' %
 391                       self._CreateValueFromType(choice, '*%s' % choice_var))
 392         .Eblock('}')
 393       )
 394     (c.Append('DCHECK(result) << "Must set at least one choice for %s";' %
 395                   type_.unix_name)
 396       .Append('return result.Pass();')
 397       .Eblock('}')
 398     )
 399     return c
 400
 401   def _GenerateFunction(self, function):
 402     """Generates the definitions for function structs.
 403     """
 404     c = Code()
 405
 406     # TODO(kalman): use function.unix_name not Classname.
 407     function_namespace = cpp_util.Classname(function.name)
 408     # Windows has a #define for SendMessage, so to avoid any issues, we need
 409     # to not use the name.
 410     if function_namespace == 'SendMessage':
 411       function_namespace = 'PassMessage'
 412     (c.Append('namespace %s {' % function_namespace)
 413       .Append()
 414     )
 415
 416     # Params::Populate function
 417     if function.params:
 418       c.Concat(self._GeneratePropertyFunctions('Params', function.params))
 419       (c.Append('Params::Params() {}')
 420         .Append('Params::~Params() {}')
 421         .Append()
 422         .Cblock(self._GenerateFunctionParamsCreate(function))
 423       )
 424
 425     # Results::Create function
 426     if function.callback:
 427       c.Concat(self._GenerateCreateCallbackArguments('Results',
 428                                                      function.callback))
 429
 430     c.Append('}  // namespace %s' % function_namespace)
 431     return c
 432
 433   def _GenerateEvent(self, event):
 434     # TODO(kalman): use event.unix_name not Classname.
 435     c = Code()
 436     event_namespace = cpp_util.Classname(event.name)
 437     (c.Append('namespace %s {' % event_namespace)
 438       .Append()
 439       .Cblock(self._GenerateEventNameConstant(None, event))
 440       .Cblock(self._GenerateCreateCallbackArguments(None, event))
 441       .Append('}  // namespace %s' % event_namespace)
 442     )
 443     return c
 444
 445   def _CreateValueFromType(self, type_, var, is_ptr=False):
 446     """Creates a base::Value given a type. Generated code passes ownership
 447     to caller.
 448
 449     var: variable or variable*
 450
 451     E.g for std::string, generate new base::StringValue(var)
 452     """
 453     underlying_type = self._type_helper.FollowRef(type_)
 454     if (underlying_type.property_type == PropertyType.CHOICES or
 455         underlying_type.property_type == PropertyType.OBJECT):
 456       if is_ptr:
 457         return '(%s)->ToValue().release()' % var
 458       else:
 459         return '(%s).ToValue().release()' % var
 460     elif (underlying_type.property_type == PropertyType.ANY or
 461           underlying_type.property_type == PropertyType.FUNCTION):
 462       if is_ptr:
 463         vardot = '(%s)->' % var
 464       else:
 465         vardot = '(%s).' % var
 466       return '%sDeepCopy()' % vardot
 467     elif underlying_type.property_type == PropertyType.ENUM:
 468       return 'new base::StringValue(ToString(%s))' % var
 469     elif underlying_type.property_type == PropertyType.BINARY:
 470       if is_ptr:
 471         vardot = var + '->'
 472       else:
 473         vardot = var + '.'
 474       return ('base::BinaryValue::CreateWithCopiedBuffer(%sdata(), %ssize())' %
 475               (vardot, vardot))
 476     elif underlying_type.property_type == PropertyType.ARRAY:
 477       return '%s.release()' % self._util_cc_helper.CreateValueFromArray(
 478           underlying_type,
 479           var,
 480           is_ptr)
 481     elif underlying_type.property_type.is_fundamental:
 482       if is_ptr:
 483         var = '*%s' % var
 484       if underlying_type.property_type == PropertyType.STRING:
 485         return 'new base::StringValue(%s)' % var
 486       else:
 487         return 'new base::FundamentalValue(%s)' % var
 488     else:
 489       raise NotImplementedError('Conversion of %s to base::Value not '
 490                                 'implemented' % repr(type_.type_))
 491
 492   def _GenerateParamsCheck(self, function, var):
 493     """Generates a check for the correct number of arguments when creating
 494     Params.
 495     """
 496     c = Code()
 497     num_required = 0
 498     for param in function.params:
 499       if not param.optional:
 500         num_required += 1
 501     if num_required == len(function.params):
 502       c.Sblock('if (%(var)s.GetSize() != %(total)d) {')
 503     elif not num_required:
 504       c.Sblock('if (%(var)s.GetSize() > %(total)d) {')
 505     else:
 506       c.Sblock('if (%(var)s.GetSize() < %(required)d'
 507           ' || %(var)s.GetSize() > %(total)d) {')
 508     (c.Concat(self._GenerateError(
 509         '"expected %%(total)d arguments, got " '
 510         '+ base::IntToString(%%(var)s.GetSize())'))
 511       .Append('return scoped_ptr<Params>();')
 512       .Eblock('}')
 513       .Substitute({
 514         'var': var,
 515         'required': num_required,
 516         'total': len(function.params),
 517     }))
 518     return c
 519
 520   def _GenerateFunctionParamsCreate(self, function):
 521     """Generate function to create an instance of Params. The generated
 522     function takes a base::ListValue of arguments.
 523
 524     E.g for function "Bar", generate Bar::Params::Create()
 525     """
 526     c = Code()
 527     (c.Append('// static')
 528       .Sblock('scoped_ptr<Params> Params::Create(%s) {' % self._GenerateParams(
 529         ['const base::ListValue& args']))
 530       .Concat(self._GenerateParamsCheck(function, 'args'))
 531       .Append('scoped_ptr<Params> params(new Params());'))
 532
 533     for param in function.params:
 534       c.Concat(self._InitializePropertyToDefault(param, 'params'))
 535
 536     for i, param in enumerate(function.params):
 537       # Any failure will cause this function to return. If any argument is
 538       # incorrect or missing, those following it are not processed. Note that
 539       # for optional arguments, we allow missing arguments and proceed because
 540       # there may be other arguments following it.
 541       failure_value = 'scoped_ptr<Params>()'
 542       c.Append()
 543       value_var = param.unix_name + '_value'
 544       (c.Append('const base::Value* %(value_var)s = NULL;')
 545         .Append('if (args.Get(%(i)s, &%(value_var)s) &&')
 546         .Sblock('    !%(value_var)s->IsType(base::Value::TYPE_NULL)) {')
 547         .Concat(self._GeneratePopulatePropertyFromValue(
 548             param, value_var, 'params', failure_value))
 549         .Eblock('}')
 550       )
 551       if not param.optional:
 552         (c.Sblock('else {')
 553           .Concat(self._GenerateError('"\'%%(key)s\' is required"'))
 554           .Append('return %s;' % failure_value)
 555           .Eblock('}'))
 556       c.Substitute({'value_var': value_var, 'i': i, 'key': param.name})
 557     (c.Append()
 558       .Append('return params.Pass();')
 559       .Eblock('}')
 560       .Append()
 561     )
 562
 563     return c
 564
 565   def _GeneratePopulatePropertyFromValue(self,
 566                                          prop,
 567                                          src_var,
 568                                          dst_class_var,
 569                                          failure_value):
 570     """Generates code to populate property |prop| of |dst_class_var| (a
 571     pointer) from a Value*. See |_GeneratePopulateVariableFromValue| for
 572     semantics.
 573     """
 574     return self._GeneratePopulateVariableFromValue(prop.type_,
 575                                                    src_var,
 576                                                    '%s->%s' % (dst_class_var,
 577                                                                prop.unix_name),
 578                                                    failure_value,
 579                                                    is_ptr=prop.optional)
 580
 581   def _GeneratePopulateVariableFromValue(self,
 582                                          type_,
 583                                          src_var,
 584                                          dst_var,
 585                                          failure_value,
 586                                          is_ptr=False):
 587     """Generates code to populate a variable |dst_var| of type |type_| from a
 588     Value* at |src_var|. The Value* is assumed to be non-NULL. In the generated
 589     code, if |dst_var| fails to be populated then Populate will return
 590     |failure_value|.
 591     """
 592     c = Code()
 593     c.Sblock('{')
 594
 595     underlying_type = self._type_helper.FollowRef(type_)
 596
 597     if underlying_type.property_type.is_fundamental:
 598       if is_ptr:
 599         (c.Append('%(cpp_type)s temp;')
 600           .Sblock('if (!%s) {' % cpp_util.GetAsFundamentalValue(
 601                       self._type_helper.FollowRef(type_), src_var, '&temp'))
 602           .Concat(self._GenerateError(
 603             '"\'%%(key)s\': expected ' + '%s, got " + %s' % (
 604                 type_.name,
 605                 self._util_cc_helper.GetValueTypeString(
 606                     '%%(src_var)s', True))))
 607           .Append('return %(failure_value)s;')
 608           .Eblock('}')
 609           .Append('%(dst_var)s.reset(new %(cpp_type)s(temp));')
 610         )
 611       else:
 612         (c.Sblock('if (!%s) {' % cpp_util.GetAsFundamentalValue(
 613                       self._type_helper.FollowRef(type_),
 614                       src_var,
 615                       '&%s' % dst_var))
 616           .Concat(self._GenerateError(
 617             '"\'%%(key)s\': expected ' + '%s, got " + %s' % (
 618                 type_.name,
 619                 self._util_cc_helper.GetValueTypeString(
 620                     '%%(src_var)s', True))))
 621           .Append('return %(failure_value)s;')
 622           .Eblock('}')
 623         )
 624     elif underlying_type.property_type == PropertyType.OBJECT:
 625       if is_ptr:
 626         (c.Append('const base::DictionaryValue* dictionary = NULL;')
 627           .Sblock('if (!%(src_var)s->GetAsDictionary(&dictionary)) {')
 628           .Concat(self._GenerateError(
 629             '"\'%%(key)s\': expected dictionary, got " + ' +
 630             self._util_cc_helper.GetValueTypeString('%%(src_var)s', True)))
 631           .Append('return %(failure_value)s;')
 632           .Eblock('}')
 633           .Append('scoped_ptr<%(cpp_type)s> temp(new %(cpp_type)s());')
 634           .Append('if (!%%(cpp_type)s::Populate(%s)) {' % self._GenerateArgs(
 635             ('*dictionary', 'temp.get()')))
 636           .Append('  return %(failure_value)s;')
 637           .Append('}')
 638           .Append('%(dst_var)s = temp.Pass();')
 639         )
 640       else:
 641         (c.Append('const base::DictionaryValue* dictionary = NULL;')
 642           .Sblock('if (!%(src_var)s->GetAsDictionary(&dictionary)) {')
 643           .Concat(self._GenerateError(
 644             '"\'%%(key)s\': expected dictionary, got " + ' +
 645             self._util_cc_helper.GetValueTypeString('%%(src_var)s', True)))
 646           .Append('return %(failure_value)s;')
 647           .Eblock('}')
 648           .Append('if (!%%(cpp_type)s::Populate(%s)) {' % self._GenerateArgs(
 649             ('*dictionary', '&%(dst_var)s')))
 650           .Append('  return %(failure_value)s;')
 651           .Append('}')
 652         )
 653     elif underlying_type.property_type == PropertyType.FUNCTION:
 654       if is_ptr:
 655         c.Append('%(dst_var)s.reset(new base::DictionaryValue());')
 656     elif underlying_type.property_type == PropertyType.ANY:
 657       c.Append('%(dst_var)s.reset(%(src_var)s->DeepCopy());')
 658     elif underlying_type.property_type == PropertyType.ARRAY:
 659       # util_cc_helper deals with optional and required arrays
 660       (c.Append('const base::ListValue* list = NULL;')
 661         .Sblock('if (!%(src_var)s->GetAsList(&list)) {')
 662           .Concat(self._GenerateError(
 663             '"\'%%(key)s\': expected list, got " + ' +
 664             self._util_cc_helper.GetValueTypeString('%%(src_var)s', True)))
 665           .Append('return %(failure_value)s;')
 666           .Eblock('}'))
 667       item_type = self._type_helper.FollowRef(underlying_type.item_type)
 668       if item_type.property_type == PropertyType.ENUM:
 669         c.Concat(self._GenerateListValueToEnumArrayConversion(
 670                      item_type,
 671                      'list',
 672                      dst_var,
 673                      failure_value,
 674                      is_ptr=is_ptr))
 675       else:
 676         (c.Sblock('if (!%s) {' % self._util_cc_helper.PopulateArrayFromList(
 677               underlying_type,
 678               'list',
 679               dst_var,
 680               is_ptr))
 681           .Concat(self._GenerateError(
 682             '"unable to populate array \'%%(parent_key)s\'"'))
 683           .Append('return %(failure_value)s;')
 684           .Eblock('}')
 685         )
 686     elif underlying_type.property_type == PropertyType.CHOICES:
 687       if is_ptr:
 688         (c.Append('scoped_ptr<%(cpp_type)s> temp(new %(cpp_type)s());')
 689           .Append('if (!%%(cpp_type)s::Populate(%s))' % self._GenerateArgs(
 690             ('*%(src_var)s', 'temp.get()')))
 691           .Append('  return %(failure_value)s;')
 692           .Append('%(dst_var)s = temp.Pass();')
 693         )
 694       else:
 695         (c.Append('if (!%%(cpp_type)s::Populate(%s))' % self._GenerateArgs(
 696             ('*%(src_var)s', '&%(dst_var)s')))
 697           .Append('  return %(failure_value)s;'))
 698     elif underlying_type.property_type == PropertyType.ENUM:
 699       c.Concat(self._GenerateStringToEnumConversion(type_,
 700                                                     src_var,
 701                                                     dst_var,
 702                                                     failure_value))
 703     elif underlying_type.property_type == PropertyType.BINARY:
 704       (c.Sblock('if (!%(src_var)s->IsType(base::Value::TYPE_BINARY)) {')
 705         .Concat(self._GenerateError(
 706           '"\'%%(key)s\': expected binary, got " + ' +
 707           self._util_cc_helper.GetValueTypeString('%%(src_var)s', True)))
 708         .Append('return %(failure_value)s;')
 709         .Eblock('}')
 710         .Append('const base::BinaryValue* binary_value =')
 711         .Append('    static_cast<const base::BinaryValue*>(%(src_var)s);')
 712       )
 713       if is_ptr:
 714         (c.Append('%(dst_var)s.reset(')
 715           .Append('    new std::string(binary_value->GetBuffer(),')
 716           .Append('                    binary_value->GetSize()));')
 717         )
 718       else:
 719         (c.Append('%(dst_var)s.assign(binary_value->GetBuffer(),')
 720           .Append('                   binary_value->GetSize());')
 721         )
 722     else:
 723       raise NotImplementedError(type_)
 724     return c.Eblock('}').Substitute({
 725       'cpp_type': self._type_helper.GetCppType(type_),
 726       'src_var': src_var,
 727       'dst_var': dst_var,
 728       'failure_value': failure_value,
 729       'key': type_.name,
 730       'parent_key': type_.parent.name
 731     })
 732
 733   def _GenerateListValueToEnumArrayConversion(self,
 734                                               item_type,
 735                                               src_var,
 736                                               dst_var,
 737                                               failure_value,
 738                                               is_ptr=False):
 739     """Returns Code that converts a ListValue of string constants from
 740     |src_var| into an array of enums of |type_| in |dst_var|. On failure,
 741     returns |failure_value|.
 742     """
 743     c = Code()
 744     accessor = '.'
 745     if is_ptr:
 746       accessor = '->'
 747       cpp_type = self._type_helper.GetCppType(item_type, is_in_container=True)
 748       c.Append('%s.reset(new std::vector<%s>);' %
 749                    (dst_var, cpp_util.PadForGenerics(cpp_type)))
 750     (c.Sblock('for (base::ListValue::const_iterator it = %s->begin(); '
 751                    'it != %s->end(); ++it) {' % (src_var, src_var))
 752       .Append('%s tmp;' % self._type_helper.GetCppType(item_type))
 753       .Concat(self._GenerateStringToEnumConversion(item_type,
 754                                                    '(*it)',
 755                                                    'tmp',
 756                                                    failure_value))
 757       .Append('%s%spush_back(tmp);' % (dst_var, accessor))
 758       .Eblock('}')
 759     )
 760     return c
 761
 762   def _GenerateStringToEnumConversion(self,
 763                                       type_,
 764                                       src_var,
 765                                       dst_var,
 766                                       failure_value):
 767     """Returns Code that converts a string type in |src_var| to an enum with
 768     type |type_| in |dst_var|. In the generated code, if |src_var| is not
 769     a valid enum name then the function will return |failure_value|.
 770     """
 771     c = Code()
 772     enum_as_string = '%s_as_string' % type_.unix_name
 773     (c.Append('std::string %s;' % enum_as_string)
 774       .Sblock('if (!%s->GetAsString(&%s)) {' % (src_var, enum_as_string))
 775       .Concat(self._GenerateError(
 776         '"\'%%(key)s\': expected string, got " + ' +
 777         self._util_cc_helper.GetValueTypeString('%%(src_var)s', True)))
 778       .Append('return %s;' % failure_value)
 779       .Eblock('}')
 780       .Append('%s = Parse%s(%s);' % (dst_var,
 781                                      self._type_helper.GetCppType(type_),
 782                                      enum_as_string))
 783       .Sblock('if (%s == %s) {' % (dst_var,
 784                                  self._type_helper.GetEnumNoneValue(type_)))
 785       .Concat(self._GenerateError(
 786         '\"\'%%(key)s\': expected \\"' +
 787         '\\" or \\"'.join(self._type_helper.FollowRef(type_).enum_values) +
 788         '\\", got \\"" + %s + "\\""' % enum_as_string))
 789       .Append('return %s;' % failure_value)
 790       .Eblock('}')
 791       .Substitute({'src_var': src_var, 'key': type_.name})
 792     )
 793     return c
 794
 795   def _GeneratePropertyFunctions(self, namespace, params):
 796     """Generates the member functions for a list of parameters.
 797     """
 798     return self._GenerateTypes(namespace, (param.type_ for param in params))
 799
 800   def _GenerateTypes(self, namespace, types):
 801     """Generates the member functions for a list of types.
 802     """
 803     c = Code()
 804     for type_ in types:
 805       c.Cblock(self._GenerateType(namespace, type_))
 806     return c
 807
 808   def _GenerateEnumToString(self, cpp_namespace, type_):
 809     """Generates ToString() which gets the string representation of an enum.
 810     """
 811     c = Code()
 812     classname = cpp_util.Classname(schema_util.StripNamespace(type_.name))
 813
 814     if cpp_namespace is not None:
 815       c.Append('// static')
 816     maybe_namespace = '' if cpp_namespace is None else '%s::' % cpp_namespace
 817
 818     c.Sblock('std::string %sToString(%s enum_param) {' %
 819                  (maybe_namespace, classname))
 820     c.Sblock('switch (enum_param) {')
 821     for enum_value in self._type_helper.FollowRef(type_).enum_values:
 822       (c.Append('case %s: ' % self._type_helper.GetEnumValue(type_, enum_value))
 823         .Append('  return "%s";' % enum_value))
 824     (c.Append('case %s:' % self._type_helper.GetEnumNoneValue(type_))
 825       .Append('  return "";')
 826       .Eblock('}')
 827       .Append('NOTREACHED();')
 828       .Append('return "";')
 829       .Eblock('}')
 830     )
 831     return c
 832
 833   def _GenerateEnumFromString(self, cpp_namespace, type_):
 834     """Generates FromClassNameString() which gets an enum from its string
 835     representation.
 836     """
 837     c = Code()
 838     classname = cpp_util.Classname(schema_util.StripNamespace(type_.name))
 839
 840     if cpp_namespace is not None:
 841       c.Append('// static')
 842     maybe_namespace = '' if cpp_namespace is None else '%s::' % cpp_namespace
 843
 844     c.Sblock('%s%s %sParse%s(const std::string& enum_string) {' %
 845                  (maybe_namespace, classname, maybe_namespace, classname))
 846     for i, enum_value in enumerate(
 847           self._type_helper.FollowRef(type_).enum_values):
 848       # This is broken up into all ifs with no else ifs because we get
 849       # "fatal error C1061: compiler limit : blocks nested too deeply"
 850       # on Windows.
 851       (c.Append('if (enum_string == "%s")' % enum_value)
 852         .Append('  return %s;' %
 853             self._type_helper.GetEnumValue(type_, enum_value)))
 854     (c.Append('return %s;' % self._type_helper.GetEnumNoneValue(type_))
 855       .Eblock('}')
 856     )
 857     return c
 858
 859   def _GenerateCreateCallbackArguments(self, function_scope, callback):
 860     """Generate all functions to create Value parameters for a callback.
 861
 862     E.g for function "Bar", generate Bar::Results::Create
 863     E.g for event "Baz", generate Baz::Create
 864
 865     function_scope: the function scope path, e.g. Foo::Bar for the function
 866                     Foo::Bar::Baz(). May be None if there is no function scope.
 867     callback: the Function object we are creating callback arguments for.
 868     """
 869     c = Code()
 870     params = callback.params
 871     c.Concat(self._GeneratePropertyFunctions(function_scope, params))
 872
 873     (c.Sblock('scoped_ptr<base::ListValue> %(function_scope)s'
 874                   'Create(%(declaration_list)s) {')
 875       .Append('scoped_ptr<base::ListValue> create_results('
 876               'new base::ListValue());')
 877     )
 878     declaration_list = []
 879     for param in params:
 880       declaration_list.append(cpp_util.GetParameterDeclaration(
 881           param, self._type_helper.GetCppType(param.type_)))
 882       c.Append('create_results->Append(%s);' %
 883           self._CreateValueFromType(param.type_, param.unix_name))
 884     c.Append('return create_results.Pass();')
 885     c.Eblock('}')
 886     c.Substitute({
 887         'function_scope': ('%s::' % function_scope) if function_scope else '',
 888         'declaration_list': ', '.join(declaration_list),
 889         'param_names': ', '.join(param.unix_name for param in params)
 890     })
 891     return c
 892
 893   def _GenerateEventNameConstant(self, function_scope, event):
 894     """Generates a constant string array for the event name.
 895     """
 896     c = Code()
 897     c.Append('const char kEventName[] = "%s.%s";' % (
 898                  self._namespace.name, event.name))
 899     return c
 900
 901   def _InitializePropertyToDefault(self, prop, dst):
 902     """Initialize a model.Property to its default value inside an object.
 903
 904     E.g for optional enum "state", generate dst->state = STATE_NONE;
 905
 906     dst: Type*
 907     """
 908     c = Code()
 909     underlying_type = self._type_helper.FollowRef(prop.type_)
 910     if (underlying_type.property_type == PropertyType.ENUM and
 911         prop.optional):
 912       c.Append('%s->%s = %s;' % (
 913         dst,
 914         prop.unix_name,
 915         self._type_helper.GetEnumNoneValue(prop.type_)))
 916     return c
 917
 918   def _GenerateError(self, body):
 919     """Generates an error message pertaining to population failure.
 920
 921     E.g 'expected bool, got int'
 922     """
 923     c = Code()
 924     if not self._generate_error_messages:
 925       return c
 926     (c.Append('if (error)')
 927       .Append('  *error = UTF8ToUTF16(' + body + ');'))
 928     return c
 929
 930   def _GenerateParams(self, params):
 931     """Builds the parameter list for a function, given an array of parameters.
 932     """
 933     if self._generate_error_messages:
 934       params = list(params) + ['base::string16* error']
 935     return ', '.join(str(p) for p in params)
 936
 937   def _GenerateArgs(self, args):
 938     """Builds the argument list for a function, given an array of arguments.
 939     """
 940     if self._generate_error_messages:
 941       args = list(args) + ['error']
 942     return ', '.join(str(a) for a in args)