import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

dom/bindings/Configuration.py

@@ -0,0 +1,791 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from WebIDL import IDLImplementsStatement
+import os
+from collections import defaultdict
+
+autogenerated_comment = "/* THIS FILE IS AUTOGENERATED - DO NOT EDIT */\n"
+
+
+class DescriptorProvider:
+    """
+    A way of getting descriptors for interface names.  Subclasses must
+    have a getDescriptor method callable with the interface name only.
+    """
+    def __init__(self):
+        pass
+
+
+class Configuration(DescriptorProvider):
+    """
+    Represents global configuration state based on IDL parse data and
+    the configuration file.
+    """
+    def __init__(self, filename, parseData, generatedEvents=[]):
+        DescriptorProvider.__init__(self)
+
+        # Read the configuration file.
+        glbl = {}
+        execfile(filename, glbl)
+        config = glbl['DOMInterfaces']
+
+        # Build descriptors for all the interfaces we have in the parse data.
+        # This allows callers to specify a subset of interfaces by filtering
+        # |parseData|.
+        self.descriptors = []
+        self.interfaces = {}
+        self.descriptorsByName = {}
+        self.optimizedOutDescriptorNames = set()
+        self.generatedEvents = generatedEvents
+        self.maxProtoChainLength = 0
+        for thing in parseData:
+            if isinstance(thing, IDLImplementsStatement):
+                # Our build system doesn't support dep build involving
+                # addition/removal of "implements" statements that appear in a
+                # different .webidl file than their LHS interface.  Make sure we
+                # don't have any of those.
+                #
+                # But whitelist a RHS that is LegacyQueryInterface,
+                # since people shouldn't be adding any of those.
+                if (thing.implementor.filename() != thing.filename() and
+                    thing.implementee.identifier.name != "LegacyQueryInterface"):
+                    raise TypeError(
+                        "The binding build system doesn't really support "
+                        "'implements' statements which don't appear in the "
+                        "file in which the left-hand side of the statement is "
+                        "defined.  Don't do this unless your right-hand side "
+                        "is LegacyQueryInterface.\n"
+                        "%s\n"
+                        "%s" %
+                        (thing.location, thing.implementor.location))
+
+            assert not thing.isType()
+
+            if not thing.isInterface() and not thing.isNamespace():
+                continue
+            iface = thing
+            self.interfaces[iface.identifier.name] = iface
+            if iface.identifier.name not in config:
+                # Completely skip consequential interfaces with no descriptor
+                # if they have no interface object because chances are we
+                # don't need to do anything interesting with them.
+                if iface.isConsequential() and not iface.hasInterfaceObject():
+                    self.optimizedOutDescriptorNames.add(iface.identifier.name)
+                    continue
+                entry = {}
+            else:
+                entry = config[iface.identifier.name]
+            assert not isinstance(entry, list)
+            desc = Descriptor(self, iface, entry)
+            self.descriptors.append(desc)
+            # Setting up descriptorsByName while iterating through interfaces
+            # means we can get the nativeType of iterable interfaces without
+            # having to do multiple loops.
+            assert desc.interface.identifier.name not in self.descriptorsByName
+            self.descriptorsByName[desc.interface.identifier.name] = desc
+
+        # Keep the descriptor list sorted for determinism.
+        self.descriptors.sort(lambda x, y: cmp(x.name, y.name))
+
+
+        self.descriptorsByFile = {}
+        for d in self.descriptors:
+            self.descriptorsByFile.setdefault(d.interface.filename(),
+                                              []).append(d)
+
+        self.enums = [e for e in parseData if e.isEnum()]
+
+        self.dictionaries = [d for d in parseData if d.isDictionary()]
+        self.callbacks = [c for c in parseData if
+                          c.isCallback() and not c.isInterface()]
+
+        # Dictionary mapping from a union type name to a set of filenames where
+        # union types with that name are used.
+        self.filenamesPerUnion = defaultdict(set)
+
+        # Dictionary mapping from a filename to a list of types for
+        # the union types used in that file. If a union type is used
+        # in multiple files then it will be added to the list for the
+        # None key. Note that the list contains a type for every use
+        # of a union type, so there can be multiple entries with union
+        # types that have the same name.
+        self.unionsPerFilename = defaultdict(list)
+
+        for (t, _) in getAllTypes(self.descriptors, self.dictionaries, self.callbacks):
+            while True:
+                if t.isMozMap():
+                    t = t.inner
+                elif t.unroll() != t:
+                    t = t.unroll()
+                elif t.isPromise():
+                    t = t.promiseInnerType()
+                else:
+                    break
+            if t.isUnion():
+                filenamesForUnion = self.filenamesPerUnion[t.name]
+                if t.filename() not in filenamesForUnion:
+                    # We have a to be a bit careful: some of our built-in
+                    # typedefs are for unions, and those unions end up with
+                    # "<unknown>" as the filename.  If that happens, we don't
+                    # want to try associating this union with one particular
+                    # filename, since there isn't one to associate it with,
+                    # really.
+                    if t.filename() == "<unknown>":
+                        uniqueFilenameForUnion = None
+                    elif len(filenamesForUnion) == 0:
+                        # This is the first file that we found a union with this
+                        # name in, record the union as part of the file.
+                        uniqueFilenameForUnion = t.filename()
+                    else:
+                        # We already found a file that contains a union with
+                        # this name.
+                        if len(filenamesForUnion) == 1:
+                            # This is the first time we found a union with this
+                            # name in another file.
+                            for f in filenamesForUnion:
+                                # Filter out unions with this name from the
+                                # unions for the file where we previously found
+                                # them.
+                                unionsForFilename = self.unionsPerFilename[f]
+                                unionsForFilename = filter(lambda u: u.name != t.name,
+                                                           unionsForFilename)
+                                if len(unionsForFilename) == 0:
+                                    del self.unionsPerFilename[f]
+                                else:
+                                    self.unionsPerFilename[f] = unionsForFilename
+                        # Unions with this name appear in multiple files, record
+                        # the filename as None, so that we can detect that.
+                        uniqueFilenameForUnion = None
+                    self.unionsPerFilename[uniqueFilenameForUnion].append(t)
+                    filenamesForUnion.add(t.filename())
+
+    def getInterface(self, ifname):
+        return self.interfaces[ifname]
+
+    def getDescriptors(self, **filters):
+        """Gets the descriptors that match the given filters."""
+        curr = self.descriptors
+        # Collect up our filters, because we may have a webIDLFile filter that
+        # we always want to apply first.
+        tofilter = []
+        for key, val in filters.iteritems():
+            if key == 'webIDLFile':
+                # Special-case this part to make it fast, since most of our
+                # getDescriptors calls are conditioned on a webIDLFile.  We may
+                # not have this key, in which case we have no descriptors
+                # either.
+                curr = self.descriptorsByFile.get(val, [])
+                continue
+            elif key == 'hasInterfaceObject':
+                getter = lambda x: (not x.interface.isExternal() and
+                                    x.interface.hasInterfaceObject())
+            elif key == 'hasInterfacePrototypeObject':
+                getter = lambda x: (not x.interface.isExternal() and
+                                    x.interface.hasInterfacePrototypeObject())
+            elif key == 'hasInterfaceOrInterfacePrototypeObject':
+                getter = lambda x: x.hasInterfaceOrInterfacePrototypeObject()
+            elif key == 'isCallback':
+                getter = lambda x: x.interface.isCallback()
+            elif key == 'isExternal':
+                getter = lambda x: x.interface.isExternal()
+            elif key == 'isJSImplemented':
+                getter = lambda x: x.interface.isJSImplemented()
+            elif key == 'isNavigatorProperty':
+                getter = lambda x: x.interface.isNavigatorProperty()
+            elif key == 'isExposedInAnyWorker':
+                getter = lambda x: x.interface.isExposedInAnyWorker()
+            elif key == 'isExposedInWorkerDebugger':
+                getter = lambda x: x.interface.isExposedInWorkerDebugger()
+            elif key == 'isExposedInAnyWorklet':
+                getter = lambda x: x.interface.isExposedInAnyWorklet()
+            elif key == 'isExposedInSystemGlobals':
+                getter = lambda x: x.interface.isExposedInSystemGlobals()
+            elif key == 'isExposedInWindow':
+                getter = lambda x: x.interface.isExposedInWindow()
+            else:
+                # Have to watch out: just closing over "key" is not enough,
+                # since we're about to mutate its value
+                getter = (lambda attrName: lambda x: getattr(x, attrName))(key)
+            tofilter.append((getter, val))
+        for f in tofilter:
+            curr = filter(lambda x: f[0](x) == f[1], curr)
+        return curr
+
+    def getEnums(self, webIDLFile):
+        return filter(lambda e: e.filename() == webIDLFile, self.enums)
+
+    def getDictionaries(self, webIDLFile):
+        return filter(lambda d: d.filename() == webIDLFile, self.dictionaries)
+
+    def getCallbacks(self, webIDLFile):
+        return filter(lambda c: c.filename() == webIDLFile, self.callbacks)
+
+    def getDescriptor(self, interfaceName):
+        """
+        Gets the appropriate descriptor for the given interface name.
+        """
+        # We may have optimized out this descriptor, but the chances of anyone
+        # asking about it are then slim.  Put the check for that _after_ we've
+        # done our normal lookup.  But that means we have to do our normal
+        # lookup in a way that will not throw if it fails.
+        d = self.descriptorsByName.get(interfaceName, None)
+        if d:
+            return d
+
+        if interfaceName in self.optimizedOutDescriptorNames:
+            raise NoSuchDescriptorError(
+                "No descriptor for '%s', which is a mixin ([NoInterfaceObject] "
+                "and a consequential interface) without an explicit "
+                "Bindings.conf annotation." % interfaceName)
+
+        raise NoSuchDescriptorError("For " + interfaceName + " found no matches")
+
+
+class NoSuchDescriptorError(TypeError):
+    def __init__(self, str):
+        TypeError.__init__(self, str)
+
+
+def methodReturnsJSObject(method):
+    assert method.isMethod()
+    if method.returnsPromise():
+        return True
+
+    for signature in method.signatures():
+        returnType = signature[0]
+        if returnType.isObject() or returnType.isSpiderMonkeyInterface():
+            return True
+
+    return False
+
+
+def MemberIsUnforgeable(member, descriptor):
+    # Note: "or" and "and" return either their LHS or RHS, not
+    # necessarily booleans.  Make sure to return a boolean from this
+    # method, because callers will compare its return value to
+    # booleans.
+    return bool((member.isAttr() or member.isMethod()) and
+                not member.isStatic() and
+                (member.isUnforgeable() or
+                 descriptor.interface.getExtendedAttribute("Unforgeable")))
+
+
+class Descriptor(DescriptorProvider):
+    """
+    Represents a single descriptor for an interface. See Bindings.conf.
+    """
+    def __init__(self, config, interface, desc):
+        DescriptorProvider.__init__(self)
+        self.config = config
+        self.interface = interface
+
+        self.wantsXrays = (not interface.isExternal() and
+                           interface.isExposedInWindow())
+
+        if self.wantsXrays:
+            # We could try to restrict self.wantsXrayExpandoClass further.  For
+            # example, we could set it to false if all of our slots store
+            # Gecko-interface-typed things, because we don't use Xray expando
+            # slots for those.  But note that we would need to check the types
+            # of not only the members of "interface" but also of all its
+            # ancestors, because those can have members living in our slots too.
+            # For now, do the simple thing.
+            self.wantsXrayExpandoClass = (interface.totalMembersInSlots != 0)
+
+        # Read the desc, and fill in the relevant defaults.
+        ifaceName = self.interface.identifier.name
+        # For generated iterator interfaces for other iterable interfaces, we
+        # just use IterableIterator as the native type, templated on the
+        # nativeType of the iterable interface. That way we can have a
+        # templated implementation for all the duplicated iterator
+        # functionality.
+        if self.interface.isIteratorInterface():
+            itrName = self.interface.iterableInterface.identifier.name
+            itrDesc = self.getDescriptor(itrName)
+            nativeTypeDefault = iteratorNativeType(itrDesc)
+
+        elif self.interface.isExternal():
+            nativeTypeDefault = "nsIDOM" + ifaceName
+        else:
+            nativeTypeDefault = "mozilla::dom::" + ifaceName
+
+        self.nativeType = desc.get('nativeType', nativeTypeDefault)
+        # Now create a version of nativeType that doesn't have extra
+        # mozilla::dom:: at the beginning.
+        prettyNativeType = self.nativeType.split("::")
+        if prettyNativeType[0] == "mozilla":
+            prettyNativeType.pop(0)
+            if prettyNativeType[0] == "dom":
+                prettyNativeType.pop(0)
+        self.prettyNativeType = "::".join(prettyNativeType)
+
+        self.jsImplParent = desc.get('jsImplParent', self.nativeType)
+
+        # Do something sane for JSObject
+        if self.nativeType == "JSObject":
+            headerDefault = "js/TypeDecls.h"
+        elif self.interface.isCallback() or self.interface.isJSImplemented():
+            # A copy of CGHeaders.getDeclarationFilename; we can't
+            # import it here, sadly.
+            # Use our local version of the header, not the exported one, so that
+            # test bindings, which don't export, will work correctly.
+            basename = os.path.basename(self.interface.filename())
+            headerDefault = basename.replace('.webidl', 'Binding.h')
+        else:
+            if not self.interface.isExternal() and self.interface.getExtendedAttribute("HeaderFile"):
+                headerDefault = self.interface.getExtendedAttribute("HeaderFile")[0]
+            elif self.interface.isIteratorInterface():
+                headerDefault = "mozilla/dom/IterableIterator.h"
+            else:
+                headerDefault = self.nativeType
+                headerDefault = headerDefault.replace("::", "/") + ".h"
+        self.headerFile = desc.get('headerFile', headerDefault)
+        self.headerIsDefault = self.headerFile == headerDefault
+        if self.jsImplParent == self.nativeType:
+            self.jsImplParentHeader = self.headerFile
+        else:
+            self.jsImplParentHeader = self.jsImplParent.replace("::", "/") + ".h"
+
+        self.notflattened = desc.get('notflattened', False)
+        self.register = desc.get('register', True)
+
+        self.hasXPConnectImpls = desc.get('hasXPConnectImpls', False)
+
+        # If we're concrete, we need to crawl our ancestor interfaces and mark
+        # them as having a concrete descendant.
+        self.concrete = (not self.interface.isExternal() and
+                         not self.interface.isCallback() and
+                         not self.interface.isNamespace() and
+                         desc.get('concrete', True))
+        self.hasUnforgeableMembers = (self.concrete and
+                                      any(MemberIsUnforgeable(m, self) for m in
+                                          self.interface.members))
+        self.operations = {
+            'IndexedGetter': None,
+            'IndexedSetter': None,
+            'IndexedCreator': None,
+            'IndexedDeleter': None,
+            'NamedGetter': None,
+            'NamedSetter': None,
+            'NamedCreator': None,
+            'NamedDeleter': None,
+            'Stringifier': None,
+            'LegacyCaller': None,
+            'Jsonifier': None
+            }
+
+        # Stringifiers and jsonifiers need to be set up whether an interface is
+        # concrete or not, because they're actually prototype methods and hence
+        # can apply to instances of descendant interfaces.  Legacy callers and
+        # named/indexed operations only need to be set up on concrete
+        # interfaces, since they affect the JSClass we end up using, not the
+        # prototype object.
+        def addOperation(operation, m):
+            if not self.operations[operation]:
+                self.operations[operation] = m
+
+        # Since stringifiers go on the prototype, we only need to worry
+        # about our own stringifier, not those of our ancestor interfaces.
+        if not self.interface.isExternal():
+            for m in self.interface.members:
+                if m.isMethod() and m.isStringifier():
+                    addOperation('Stringifier', m)
+                if m.isMethod() and m.isJsonifier():
+                    addOperation('Jsonifier', m)
+
+        if self.concrete:
+            self.proxy = False
+            iface = self.interface
+            for m in iface.members:
+                # Don't worry about inheriting legacycallers either: in
+                # practice these are on most-derived prototypes.
+                if m.isMethod() and m.isLegacycaller():
+                    if not m.isIdentifierLess():
+                        raise TypeError("We don't support legacycaller with "
+                                        "identifier.\n%s" % m.location)
+                    if len(m.signatures()) != 1:
+                        raise TypeError("We don't support overloaded "
+                                        "legacycaller.\n%s" % m.location)
+                    addOperation('LegacyCaller', m)
+            while iface:
+                for m in iface.members:
+                    if not m.isMethod():
+                        continue
+
+                    def addIndexedOrNamedOperation(operation, m):
+                        if m.isIndexed():
+                            operation = 'Indexed' + operation
+                        else:
+                            assert m.isNamed()
+                            operation = 'Named' + operation
+                        addOperation(operation, m)
+
+                    if m.isGetter():
+                        addIndexedOrNamedOperation('Getter', m)
+                    if m.isSetter():
+                        addIndexedOrNamedOperation('Setter', m)
+                    if m.isCreator():
+                        addIndexedOrNamedOperation('Creator', m)
+                    if m.isDeleter():
+                        addIndexedOrNamedOperation('Deleter', m)
+                    if m.isLegacycaller() and iface != self.interface:
+                        raise TypeError("We don't support legacycaller on "
+                                        "non-leaf interface %s.\n%s" %
+                                        (iface, iface.location))
+
+                iface.setUserData('hasConcreteDescendant', True)
+                iface = iface.parent
+
+            self.proxy = (self.supportsIndexedProperties() or
+                          (self.supportsNamedProperties() and
+                           not self.hasNamedPropertiesObject) or
+                          self.hasNonOrdinaryGetPrototypeOf())
+
+            if self.proxy:
+                if (not self.operations['IndexedGetter'] and
+                    (self.operations['IndexedSetter'] or
+                     self.operations['IndexedDeleter'] or
+                     self.operations['IndexedCreator'])):
+                    raise SyntaxError("%s supports indexed properties but does "
+                                      "not have an indexed getter.\n%s" %
+                                      (self.interface, self.interface.location))
+                if (not self.operations['NamedGetter'] and
+                    (self.operations['NamedSetter'] or
+                     self.operations['NamedDeleter'] or
+                     self.operations['NamedCreator'])):
+                    raise SyntaxError("%s supports named properties but does "
+                                      "not have a named getter.\n%s" %
+                                      (self.interface, self.interface.location))
+                iface = self.interface
+                while iface:
+                    iface.setUserData('hasProxyDescendant', True)
+                    iface = iface.parent
+
+        if desc.get('wantsQI', None) is not None:
+            self._wantsQI = desc.get('wantsQI', None)
+        self.wrapperCache = (not self.interface.isCallback() and
+                             not self.interface.isIteratorInterface() and
+                             desc.get('wrapperCache', True))
+        # Nasty temporary hack for supporting both DOM and SpiderMonkey promises
+        # without too much pain
+        if self.interface.identifier.name == "Promise":
+            assert self.wrapperCache
+            # But really, we're only wrappercached if we have an interface
+            # object (that is, when we're not using SpiderMonkey promises).
+            self.wrapperCache = self.interface.hasInterfaceObject()
+
+        self.name = interface.identifier.name
+
+        # self.extendedAttributes is a dict of dicts, keyed on
+        # all/getterOnly/setterOnly and then on member name. Values are an
+        # array of extended attributes.
+        self.extendedAttributes = {'all': {}, 'getterOnly': {}, 'setterOnly': {}}
+
+        def addExtendedAttribute(attribute, config):
+            def add(key, members, attribute):
+                for member in members:
+                    self.extendedAttributes[key].setdefault(member, []).append(attribute)
+
+            if isinstance(config, dict):
+                for key in ['all', 'getterOnly', 'setterOnly']:
+                    add(key, config.get(key, []), attribute)
+            elif isinstance(config, list):
+                add('all', config, attribute)
+            else:
+                assert isinstance(config, str)
+                if config == '*':
+                    iface = self.interface
+                    while iface:
+                        add('all', map(lambda m: m.name, iface.members), attribute)
+                        iface = iface.parent
+                else:
+                    add('all', [config], attribute)
+
+        if self.interface.isJSImplemented():
+            addExtendedAttribute('implicitJSContext', ['constructor'])
+        else:
+            for attribute in ['implicitJSContext']:
+                addExtendedAttribute(attribute, desc.get(attribute, {}))
+
+        if self.interface.identifier.name == 'Navigator':
+            for m in self.interface.members:
+                if m.isAttr() and m.navigatorObjectGetter:
+                    # These getters call ConstructNavigatorObject to construct
+                    # the value, and ConstructNavigatorObject needs a JSContext.
+                    self.extendedAttributes['all'].setdefault(m.identifier.name, []).append('implicitJSContext')
+
+        self._binaryNames = desc.get('binaryNames', {})
+        self._binaryNames.setdefault('__legacycaller', 'LegacyCall')
+        self._binaryNames.setdefault('__stringifier', 'Stringify')
+
+        if not self.interface.isExternal():
+            def isTestInterface(iface):
+                return (iface.identifier.name in ["TestInterface",
+                                                  "TestJSImplInterface",
+                                                  "TestRenamedInterface"])
+
+            for member in self.interface.members:
+                if not member.isAttr() and not member.isMethod():
+                    continue
+                binaryName = member.getExtendedAttribute("BinaryName")
+                if binaryName:
+                    assert isinstance(binaryName, list)
+                    assert len(binaryName) == 1
+                    self._binaryNames.setdefault(member.identifier.name,
+                                                 binaryName[0])
+
+        # Build the prototype chain.
+        self.prototypeChain = []
+        parent = interface
+        while parent:
+            self.prototypeChain.insert(0, parent.identifier.name)
+            parent = parent.parent
+        config.maxProtoChainLength = max(config.maxProtoChainLength,
+                                         len(self.prototypeChain))
+
+    def binaryNameFor(self, name):
+        return self._binaryNames.get(name, name)
+
+    @property
+    def prototypeNameChain(self):
+        return map(lambda p: self.getDescriptor(p).name, self.prototypeChain)
+
+    @property
+    def parentPrototypeName(self):
+        if len(self.prototypeChain) == 1:
+            return None
+        return self.getDescriptor(self.prototypeChain[-2]).name
+
+    def hasInterfaceOrInterfacePrototypeObject(self):
+
+        # Forward-declared interfaces don't need either interface object or
+        # interface prototype object as they're going to use QI.
+        if self.interface.isExternal():
+            return False
+
+        return self.interface.hasInterfaceObject() or self.interface.hasInterfacePrototypeObject()
+
+    @property
+    def hasNamedPropertiesObject(self):
+        if self.interface.isExternal():
+            return False
+
+        return self.isGlobal() and self.supportsNamedProperties()
+
+    def getExtendedAttributes(self, member, getter=False, setter=False):
+        def ensureValidThrowsExtendedAttribute(attr):
+            if (attr is not None and attr is not True):
+                raise TypeError("Unknown value for 'Throws': " + attr[0])
+
+        def maybeAppendInfallibleToAttrs(attrs, throws):
+            ensureValidThrowsExtendedAttribute(throws)
+            if throws is None:
+                attrs.append("infallible")
+
+        name = member.identifier.name
+        throws = self.interface.isJSImplemented() or member.getExtendedAttribute("Throws")
+        if member.isMethod():
+            # JSObject-returning [NewObject] methods must be fallible,
+            # since they have to (fallibly) allocate the new JSObject.
+            if (member.getExtendedAttribute("NewObject") and
+                methodReturnsJSObject(member)):
+                throws = True
+            attrs = self.extendedAttributes['all'].get(name, [])
+            maybeAppendInfallibleToAttrs(attrs, throws)
+            return attrs
+
+        assert member.isAttr()
+        assert bool(getter) != bool(setter)
+        key = 'getterOnly' if getter else 'setterOnly'
+        attrs = self.extendedAttributes['all'].get(name, []) + self.extendedAttributes[key].get(name, [])
+        if throws is None:
+            throwsAttr = "GetterThrows" if getter else "SetterThrows"
+            throws = member.getExtendedAttribute(throwsAttr)
+        maybeAppendInfallibleToAttrs(attrs, throws)
+        return attrs
+
+    def supportsIndexedProperties(self):
+        return self.operations['IndexedGetter'] is not None
+
+    def supportsNamedProperties(self):
+        return self.operations['NamedGetter'] is not None
+
+    def hasNonOrdinaryGetPrototypeOf(self):
+        return self.interface.getExtendedAttribute("NonOrdinaryGetPrototypeOf")
+
+    def needsHeaderInclude(self):
+        """
+        An interface doesn't need a header file if it is not concrete, not
+        pref-controlled, has no prototype object, has no static methods or
+        attributes and has no parent.  The parent matters because we assert
+        things about refcounting that depend on the actual underlying type if we
+        have a parent.
+
+        """
+        return (self.interface.isExternal() or self.concrete or
+                self.interface.hasInterfacePrototypeObject() or
+                any((m.isAttr() or m.isMethod()) and m.isStatic() for m in self.interface.members) or
+                self.interface.parent)
+
+    def hasThreadChecks(self):
+        # isExposedConditionally does not necessarily imply thread checks
+        # (since at least [SecureContext] is independent of them), but we're
+        # only used to decide whether to include nsThreadUtils.h, so we don't
+        # worry about that.
+        return ((self.isExposedConditionally() and
+                 not self.interface.isExposedInWindow()) or
+                self.interface.isExposedInSomeButNotAllWorkers())
+
+    def isExposedConditionally(self):
+        return (self.interface.isExposedConditionally() or
+                self.interface.isExposedInSomeButNotAllWorkers())
+
+    def needsXrayResolveHooks(self):
+        """
+        Generally, any interface with NeedResolve needs Xray
+        resolveOwnProperty and enumerateOwnProperties hooks.  But for
+        the special case of plugin-loading elements, we do NOT want
+        those, because we don't want to instantiate plug-ins simply
+        due to chrome touching them and that's all those hooks do on
+        those elements.  So we special-case those here.
+        """
+        return (self.interface.getExtendedAttribute("NeedResolve") and
+                self.interface.identifier.name not in ["HTMLObjectElement",
+                                                       "HTMLEmbedElement",
+                                                       "HTMLAppletElement"])
+    def needsXrayNamedDeleterHook(self):
+        return self.operations["NamedDeleter"] is not None
+
+    def needsSpecialGenericOps(self):
+        """
+        Returns true if this descriptor requires generic ops other than
+        GenericBindingMethod/GenericBindingGetter/GenericBindingSetter.
+
+        In practice we need to do this if our this value might be an XPConnect
+        object or if we need to coerce null/undefined to the global.
+        """
+        return self.hasXPConnectImpls or self.interface.isOnGlobalProtoChain()
+
+    def isGlobal(self):
+        """
+        Returns true if this is the primary interface for a global object
+        of some sort.
+        """
+        return (self.interface.getExtendedAttribute("Global") or
+                self.interface.getExtendedAttribute("PrimaryGlobal"))
+
+    @property
+    def namedPropertiesEnumerable(self):
+        """
+        Returns whether this interface should have enumerable named properties
+        """
+        assert self.proxy
+        assert self.supportsNamedProperties()
+        iface = self.interface
+        while iface:
+            if iface.getExtendedAttribute("LegacyUnenumerableNamedProperties"):
+                return False
+            iface = iface.parent
+        return True
+
+    @property
+    def registersGlobalNamesOnWindow(self):
+        return (not self.interface.isExternal() and
+                self.interface.hasInterfaceObject() and
+                self.interface.isExposedInWindow() and
+                self.register)
+
+    def getDescriptor(self, interfaceName):
+        """
+        Gets the appropriate descriptor for the given interface name.
+        """
+        return self.config.getDescriptor(interfaceName)
+
+
+# Some utility methods
+def getTypesFromDescriptor(descriptor):
+    """
+    Get all argument and return types for all members of the descriptor
+    """
+    members = [m for m in descriptor.interface.members]
+    if descriptor.interface.ctor():
+        members.append(descriptor.interface.ctor())
+    members.extend(descriptor.interface.namedConstructors)
+    signatures = [s for m in members if m.isMethod() for s in m.signatures()]
+    types = []
+    for s in signatures:
+        assert len(s) == 2
+        (returnType, arguments) = s
+        types.append(returnType)
+        types.extend(a.type for a in arguments)
+
+    types.extend(a.type for a in members if a.isAttr())
+
+    if descriptor.interface.maplikeOrSetlikeOrIterable:
+        maplikeOrSetlikeOrIterable = descriptor.interface.maplikeOrSetlikeOrIterable
+        if maplikeOrSetlikeOrIterable.hasKeyType():
+            types.append(maplikeOrSetlikeOrIterable.keyType)
+        if maplikeOrSetlikeOrIterable.hasValueType():
+            types.append(maplikeOrSetlikeOrIterable.valueType)
+    return types
+
+
+def getFlatTypes(types):
+    retval = set()
+    for type in types:
+        type = type.unroll()
+        if type.isUnion():
+            retval |= set(type.flatMemberTypes)
+        else:
+            retval.add(type)
+    return retval
+
+
+def getTypesFromDictionary(dictionary):
+    """
+    Get all member types for this dictionary
+    """
+    types = []
+    curDict = dictionary
+    while curDict:
+        types.extend([m.type for m in curDict.members])
+        curDict = curDict.parent
+    return types
+
+
+def getTypesFromCallback(callback):
+    """
+    Get the types this callback depends on: its return type and the
+    types of its arguments.
+    """
+    sig = callback.signatures()[0]
+    types = [sig[0]]  # Return type
+    types.extend(arg.type for arg in sig[1])  # Arguments
+    return types
+
+
+def getAllTypes(descriptors, dictionaries, callbacks):
+    """
+    Generate all the types we're dealing with.  For each type, a tuple
+    containing type, dictionary is yielded.  The dictionary can be None if the
+    type does not come from a dictionary.
+    """
+    for d in descriptors:
+        if d.interface.isExternal():
+            continue
+        for t in getTypesFromDescriptor(d):
+            yield (t, None)
+    for dictionary in dictionaries:
+        for t in getTypesFromDictionary(dictionary):
+            yield (t, dictionary)
+    for callback in callbacks:
+        for t in getTypesFromCallback(callback):
+            yield (t, None)
+
+def iteratorNativeType(descriptor):
+    assert descriptor.interface.isIterable()
+    iterableDecl = descriptor.interface.maplikeOrSetlikeOrIterable
+    assert iterableDecl.isPairIterator()
+    return "mozilla::dom::IterableIterator<%s>" % descriptor.nativeType