Bug 1009645 - Implement [FeatureDetectible] extended attribute and ho…

…ok it up to navigator.getFeature. r=bz

dom/base/Navigator.cpp

@@ -106,6 +106,8 @@
 #endif
 #include "mozilla/dom/ContentChild.h"
 
+#include "mozilla/dom/FeatureList.h"
+
 namespace mozilla {
 namespace dom {
 
@@ -1534,6 +1536,18 @@ Navigator::GetFeature(const nsAString& aName)
     }
   }
 
+  NS_NAMED_LITERAL_STRING(apiWindowPrefix, "api.window.");
+  if (StringBeginsWith(aName, apiWindowPrefix)) {
+    const nsAString& featureName = Substring(aName, apiWindowPrefix.Length(), aName.Length()-apiWindowPrefix.Length());
+    printf_stderr("apiWindowPrefix.Length(): %d, aName.Length(): %d\n", apiWindowPrefix.Length(), aName.Length());
+    if (IsFeatureDetectible(featureName)) {
+      p->MaybeResolve(true);
+    } else {
+      p->MaybeResolve(JS::UndefinedHandleValue);
+    }
+    return p.forget();
+  }
+
   // resolve with <undefined> because the feature name is not supported
   p->MaybeResolve(JS::UndefinedHandleValue);
 

dom/bindings/Codegen.py

@@ -13667,6 +13667,36 @@ def UnionConversions(config):
         # Done.
         return curr
 
+    @staticmethod
+    def FeatureList(config):
+        things = set()
+        for d in config.getDescriptors():
+            if not d.interface.isExternal() and d.featureDetectibleThings is not None:
+                things.update(d.featureDetectibleThings)
+        things = CGList((CGGeneric(declare='"%s",' % t) for t in sorted(things)), joiner="\n")
+        things.append(CGGeneric(declare="nullptr"))
+        things = CGWrapper(CGIndenter(things), pre="static const char* const FeatureList[] = {\n",
+                                               post="\n};\n")
+
+        helper = CGWrapper(CGIndenter(things), pre="bool IsFeatureDetectible(const nsAString& aFeature) {\n",
+                                               post=dedent("""
+              const char* const* feature = FeatureList;
+              while (*feature) {
+                if (aFeature.EqualsASCII(*feature)) {
+                  return true;
+                }
+                ++feature;
+              }
+
+              return false;
+            }
+        """))
+
+        curr = CGNamespace.build(['mozilla', 'dom'], helper)
+        curr = CGHeaders([], [], [], [], ["nsString.h"], [], 'FeatureList', curr)
+        curr = CGIncludeGuard('FeatureList', curr)
+
+        return curr
 
 # Code generator for simple events
 class CGEventGetter(CGNativeMember):

dom/bindings/Configuration.py

@@ -445,6 +445,18 @@ def addPermissions(ifaceOrMember):
                 if permissionsIndex is not None:
                     self.checkPermissionsIndicesForMembers[m.identifier.name] = permissionsIndex
 
+            self.featureDetectibleThings = set()
+            if self.interface.getExtendedAttribute("FeatureDetectible") is not None:
+                if self.interface.getNavigatorProperty():
+                    self.featureDetectibleThings.add("Navigator.%s" % self.interface.getNavigatorProperty())
+                else:
+                    assert(self.interface.ctor() is not None)
+                    self.featureDetectibleThings.add(self.interface.identifier.name)
+
+            for m in self.interface.members:
+                if m.getExtendedAttribute("FeatureDetectible") is not None:
+                    self.featureDetectibleThings.add("%s.%s" % (self.interface.identifier.name, m.identifier.name))
+
         # Build the prototype chain.
         self.prototypeChain = []
         parent = interface

dom/bindings/mozwebidlcodegen/__init__.py

@@ -127,6 +127,7 @@ class WebIDLCodegenManager(LoggingMixin):
 
     # Global parser derived declaration files.
     GLOBAL_DECLARE_FILES = {
+        'FeatureList.h',
         'GeneratedAtomList.h',
         'PrototypeList.h',
         'RegisterBindings.h',

dom/bindings/parser/WebIDL.py

@@ -568,6 +568,16 @@ def finish(self, scope):
                               [self.location])
         assert not parent or isinstance(parent, IDLInterface)
 
+        if self.getExtendedAttribute("FeatureDetectible"):
+            if self.getExtendedAttribute("NoInterfaceObject"):
+                raise WebIDLError("[FeatureDetectible] not allowed on interface "
+                                  " with [NoInterfaceObject]",
+                                  [self.location])
+            if self.getExtendedAttribute("Pref"):
+                raise WebIDLError("[FeatureDetectible] must not be specified "
+                                  "in combination with [Pref]",
+                                  [self.location])
+
         self.parent = parent
 
         assert iter(self.members)
@@ -1041,7 +1051,8 @@ def addExtendedAttributes(self, attrs):
                   identifier == "OverrideBuiltins" or
                   identifier == "ChromeOnly" or
                   identifier == "Unforgeable" or
-                  identifier == "LegacyEventInit"):
+                  identifier == "LegacyEventInit" or
+                  identifier == "FeatureDetectible"):
                 # Known extended attributes that do not take values
                 if not attr.noArguments():
                     raise WebIDLError("[%s] must take no arguments" % identifier,
@@ -2890,6 +2901,18 @@ def finish(self, scope):
             raise WebIDLError("An attribute with [SameObject] must have an "
                               "interface type as its type", [self.location])
 
+        if self.getExtendedAttribute("FeatureDetectible"):
+            if not (self.getExtendedAttribute("Func") or
+                    self.getExtendedAttribute("AvailableIn") or
+                    self.getExtendedAttribute("CheckPermissions")):
+                raise WebIDLError("[%s] is only allowed in combination with [Func], "
+                                  "[AvailableIn] or [CheckPermissions]" % identifier,
+                                  [attr.location, self.location])
+            if self.getExtendedAttribute("Pref"):
+                raise WebIDLError("[FeatureDetectible] must not be specified "
+                                  "in combination with [Pref]",
+                                  [self.location])
+
     def validate(self):
         if ((self.getExtendedAttribute("Cached") or
              self.getExtendedAttribute("StoreInSlot")) and
@@ -3008,6 +3031,13 @@ def handleExtendedAttribute(self, attr):
                 raise WebIDLError("[LenientThis] is not allowed in combination "
                                   "with [%s]" % identifier,
                                   [attr.location, self.location])
+        elif identifier == "FeatureDetectible":
+            if not (self.getExtendedAttribute("Func") or
+                    self.getExtendedAttribute("AvailableIn") or
+                    self.getExtendedAttribute("CheckPermissions")):
+                raise WebIDLError("[%s] is only allowed in combination with [Func], "
+                                  "[AvailableIn] or [CheckPermissions]" % identifier,
+                                  [attr.location, self.location])
         elif (identifier == "Pref" or
               identifier == "SetterThrows" or
               identifier == "Pure" or
@@ -3423,6 +3453,18 @@ def signatures(self):
                 self._overloads]
 
     def finish(self, scope):
+        if self.getExtendedAttribute("FeatureDetectible"):
+            if not (self.getExtendedAttribute("Func") or
+                    self.getExtendedAttribute("AvailableIn") or
+                    self.getExtendedAttribute("CheckPermissions")):
+                raise WebIDLError("[FeatureDetectible] is only allowed in combination "
+                                  "with [Func], [AvailableIn] or [CheckPermissions]",
+                                  [self.location])
+            if self.getExtendedAttribute("Pref"):
+                raise WebIDLError("[FeatureDetectible] must not be specified "
+                                      "in combination with [Pref]",
+                                      [self.location])
+
         overloadWithPromiseReturnType = None
         overloadWithoutPromiseReturnType = None
         for overload in self._overloads:
@@ -3593,7 +3635,8 @@ def handleExtendedAttribute(self, attr):
                                   [attr.location, self.location])
         elif (identifier == "Pure" or
               identifier == "CrossOriginCallable" or
-              identifier == "WebGLHandlesContextLoss"):
+              identifier == "WebGLHandlesContextLoss" or
+              identifier == "FeatureDetectible"):
             # Known no-argument attributes.
             if not attr.noArguments():
                 raise WebIDLError("[%s] must take no arguments" % identifier,