Initial commit of the Dart Chrome Extension APIs generators

tools/json_schema_compiler/dart_generator.py

+# 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.
+"""
+
+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):
+  def __init__(self, dart_overrides_dir=None):
+    self._dart_overrides_dir = dart_overrides_dir
+
+  def Generate(self, namespace):
+    return _Generator(namespace, self._dart_overrides_dir).Generate()
+
+class _Generator(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._type_overrides = {}
+    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._type_overrides[type_path] = f.read()
+
+  def Generate(self):
+    """Generates a Code object with the .dart for the entire namespace.
+    """
+    c = Code()
+    (c.Append(LICENSE)
+      .Append('// Generated from namespace: %s' % self._namespace.name)
+      .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.
+    add_public_constructor = all(not self._IsFunction(p.type_)
+                                 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.type_)]
+    if properties:
+      (c.Append()
+        .Append('/*')
+        .Append(' * Public accessors')
+        .Append(' */')
+      )
+    for prop in properties:
+      type_name = self._GetDartType(prop.type_)
+
+      # Check for custom dart for this whole property.
+      c.Append()
+      if not self._ConcatOverride(c, type_, prop, add_doc=True):
+        # Add the getter.
+        if not self._ConcatOverride(c, type_, prop, key_suffix='.get',
+                                       add_doc=True):
+          # Add the documentation for this property.
+          c.Concat(self._GenerateDocumentation(prop))
+
+          if (self._IsBaseType(prop.type_)
+              or self._IsListOfBaseTypes(prop.type_)):
+            c.Append("%s get %s => JS('%s', '#.%s', this._jsObject);" %
+                (type_name, prop.name, type_name, prop.name))
+          elif self._IsSerializableObjectType(prop.type_):
+            c.Append("%s get %s => new %s._proxy(JS('', '#.%s', "
+                     "this._jsObject));"
+              % (type_name, prop.name, type_name, prop.name))
+          elif self._IsListOfSerializableObjects(prop.type_):
+            (c.Sblock('%s get %s {' % (type_name, prop.name))
+              .Append('%s __proxy_%s = new %s();' % (type_name, prop.name,
+                                                     type_name))
+              .Sblock("for (var o in JS('List', '#.%s', this._jsObject)) {" %
+                      prop.name)
+              .Append('__proxy_%s.add(new %s._proxy(o));' % (prop.name,
+                   self._GetDartType(prop.type_.item_type)))
+              .Eblock('}')
+              .Append('return __proxy_%s;' % prop.name)
+              .Eblock('}')
+            )
+          elif self._IsObjectType(prop.type_):
+            # TODO(sashab): Think of a way to serialize generic Dart objects.
+            c.Append("%s get %s => JS('%s', '#.%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.
+        c.Append()
+        if not self._ConcatOverride(c, type_, prop, key_suffix='.set'):
+          wrapped_name = prop.name
+          if not self._IsBaseType(prop.type_):
+            wrapped_name = 'convertArgument(%s)' % prop.name
+
+          (c.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.type_)]
+    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))
+      .Concat(self._GenerateProxiedFunction(f.callback, f.callback.name))
+      .Append('%s;' % self._GenerateProxyCall(f))
+      .Eblock('}')
+    )
+
+    return c
+
+  def _GenerateProxiedFunction(self, f, callback_name):
+    """Given a function (assumed to be a callback), generates the proxied
+    version of this function, which calls |callback_name| if it is defined.
+
+    Returns a Code object.
+    """
+    c = Code()
+    proxied_params = []
+    # A list of Properties, containing List<*> objects that need proxying for
+    # their members (by copying out each member and proxying it).
+    lists_to_proxy = []
+    for p in f.params:
+      if self._IsBaseType(p.type_) or self._IsListOfBaseTypes(p.type_):
+        proxied_params.append(p.name)
+      elif self._IsSerializableObjectType(p.type_):
+        proxied_params.append('new %s._proxy(%s)' % (
+            self._GetDartType(p.type_), p.name))
+      elif self._IsListOfSerializableObjects(p.type_):
+        proxied_params.append('__proxy_%s' % p.name)
+        lists_to_proxy.append(p)
+      elif self._IsObjectType(p.type_):
+        # TODO(sashab): Find a way to build generic JS objects back in Dart.
+        proxied_params.append('%s' % p.name)
+      else:
+        raise Exception(
+            "Cannot automatically create proxy; can't wrap %s, type %s" % (
+                self._GenerateFunctionSignature(f), self._GetDartType(p.type_)))
+
+    (c.Sblock("void __proxy_callback(%s) {" % ', '.join(p.name for p in
+                                               f.params))
+      .Sblock('if (?%s) {' % callback_name)
+    )
+
+    # Add the proxied lists.
+    for list_to_proxy in lists_to_proxy:
+      (c.Append("%s __proxy_%s = new %s();" % (
+                    self._GetDartType(list_to_proxy.type_),
+                    list_to_proxy.name,
+                    self._GetDartType(list_to_proxy.type_)))
+        .Sblock("for (var o in %s) {" % list_to_proxy.name)
+        .Append('__proxy_%s.add(new %s._proxy(o));' % (list_to_proxy.name,
+            self._GetDartType(list_to_proxy.type_.item_type)))
+        .Eblock("}")
+      )
+
+    (c.Append("%s(%s);" % (callback_name, ', '.join(proxied_params)))
+      .Eblock('}')
+      .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 self._NeedsProxy(f.callback)
+
+  def _NeedsProxy(self, f):
+    """Given a function, returns True if it needs to be proxied, False if not.
+
+    A function needs to be proxied if any of its members are non-base types.
+    This means that, when the function object is passed to Javascript, it
+    needs to be wrapped in a "proxied" call that converts the JS inputs to Dart
+    objects explicitly, before calling the real function with these new objects.
+    """
+    return any(not self._IsBaseType(p.type_) for p in f.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._GetDartType(function.returns),
+              "'#.%s(%s)'" % (function.name, ', '.join(['#'] * n_params)),
+              call_target]
+
+    for param in function.params:
+      if not self._IsBaseType(param.type_):
+        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 {')
+    )
+
+    # If this event needs a proxy, all calls need to be proxied.
+    needs_proxy = self._NeedsProxy(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,
+                                               convert_optional=True)
+      if needs_proxy:
+        (c.Sblock('%s %s(void callback(%s)) {' % (ret_type, event_func,
+                                                 param_list))
+          .Concat(self._GenerateProxiedFunction(event, 'callback'))
+          .Append('super.%s(callback);' % event_func)
+          .Eblock('}')
+        )
+      else:
+        c.Append('%s %s(void callback(%s)) => super.%s(callback);' %
+            (ret_type, event_func, param_list, event_func))
+      c.Append()
+
+    # Generate the constructor.
+    (c.Append('Event_%(event_name)s(jsObject) : '
+              'super(jsObject, %(param_num)d);')
+      .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.type_):
+      return self._GenerateFunctionSignature(prop.type_.function)
+    return '%(type)s %(name)s' % {
+               'type': self._GetDartType(prop.type_),
+               '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._GetDartType(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,
+                             convert_optional=False):
+    """Given a list of function parameters, generates their signature (as a
+    string).
+
+    e.g.
+      [String type]
+      bool x, void callback([String x])
+
+    If convert_optional is True, changes optional parameters to be required.
+    Useful for callbacks, where optional parameters are treated as required.
+    """
+    # Params lists (required & optional), to be joined with commas.
+    # TODO(sashab): Don't assume optional params always come after required
+    # ones.
+    params_req = []
+    params_opt = []
+    for param in params:
+      p_sig = self._GeneratePropertySignature(param)
+      if param.optional and not convert_optional:
+        params_opt.append(p_sig)
+      else:
+        params_req.append(p_sig)
+
+    # 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 with commas.
+    # Optional parameters have to be in square brackets, e.g.:
+    #
+    #  required params | optional params |     output
+    #        []        |        []       |       ''
+    #      [x, y]      |        []       |     'x, y'
+    #        []        |      [a, b]     |    '[a, b]'
+    #      [x, y]      |      [a, b]     | 'x, y, [a, b]'
+    if params_opt:
+      params_opt[0] = '[%s' % params_opt[0]
+      params_opt[-1] = '%s]' % params_opt[-1]
+    param_sets = [', '.join(params_req), ', '.join(params_opt)]
+
+    # The 'if p' part here is needed to prevent commas where there are no
+    # parameters of a certain type.
+    # If there are no optional parameters, this prevents a _trailing_ comma,
+    # e.g. '(x, y,)'. Similarly, if there are no required parameters, this
+    # prevents a leading comma, e.g. '(, [a, b])'.
+    return ', '.join(p for p in param_sets if p)
+
+  def _ConcatOverride(self, c, type_, prop, key_suffix='', add_doc=False):
+    """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, appends the override code, and returns True.
+    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.
+    """
+    contents = self._type_overrides.get('%s.%s%s' % (type_.name, prop.name,
+                                     key_suffix))
+    if contents is None:
+      return False
+
+    if prop is not None:
+      c.Concat(self._GenerateDocumentation(prop))
+    for line in contents.split('\n'):
+      c.Append(line)
+    return True
+
+  def _IsFunction(self, type_):
+    """Given a model.Type, returns whether this type is a function.
+    """
+    return type_.property_type == PropertyType.FUNCTION
+
+  def _IsSerializableObjectType(self, type_):
+    """Given a model.Type, returns whether this type is a serializable object.
+    Serializable objects are custom types defined in this namespace.
+    """
+    if (type_.property_type == PropertyType.REF
+        and type_.ref_type in self._types):
+      return self._IsObjectType(self._types[type_.ref_type])
+    if (type_.property_type == PropertyType.OBJECT
+        and type_.instance_of in self._types):
+      return self._IsObjectType(self._types[type_.instance_of])
+    return False
+
+  def _IsObjectType(self, type_):
+    """Given a model.Type, returns whether this type is an object.
+    """
+    return (self._IsSerializableObjectType(type_)
+            or type_.property_type in [PropertyType.OBJECT, PropertyType.ANY])
+
+  def _IsListOfSerializableObjects(self, type_):
+    """Given a model.Type, returns whether this type is a list of serializable
+    objects (PropertyType.REF types).
+    """
+    return (type_.property_type is PropertyType.ARRAY and
+            type_.item_type.property_type is PropertyType.REF)
+
+  def _IsListOfBaseTypes(self, type_):
+    """Given a model.Type, returns whether this type is a list of base type
+    objects (PropertyType.REF types).
+    """
+    return (type_.property_type is PropertyType.ARRAY and
+            self._IsBaseType(type_.item_type))
+
+  def _IsBaseType(self, type_):
+    """Given a model.type_, returns whether this type is a base type
+    (string, number or boolean).
+    """
+    return (self._GetDartType(type_) in
+            ['bool', 'num', 'int', 'double', 'String'])
+
+  def _GetDartType(self, type_):
+    """Given a model.Type object, returns its type as a Dart string.
+    """
+    if type_ is None:
+      return 'void'
+
+    prop_type = type_.property_type
+    if prop_type is PropertyType.REF:
+      # TODO(sashab): If the type is foreign, it might have to be imported.
+      return StripNamespace(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'
+    elif prop_type is PropertyType.ANY:
+      return 'Object'
+    elif prop_type is PropertyType.OBJECT:
+      return type_.instance_of or 'Object'
+    elif prop_type is PropertyType.FUNCTION:
+      return 'Function'
+    elif prop_type is PropertyType.ARRAY:
+      return 'List<%s>' % self._GetDartType(type_.item_type)
+    elif prop_type is PropertyType.BINARY:
+      return 'String'
+    else:
+      raise NotImplementedError(prop_type)
+