Introduce a get_dictionary_property function to reduce duplicated code in the dictionary conversion codegen.

This also explicitly disallows dictionary members without a default value, as
the code for those doesn't currently compile.

This is the second step of my planned rewrite of the dictionary initialization
that will remove the default values we currently use to initialize the
dictionary struct in the 'new' function.

src/components/script/dom/bindings/codegen/CodegenRust.py

@@ -4204,18 +4204,18 @@ class CGDictionary(CGThing):
             "\n".join("      %s: %s," % (self.makeMemberName(m[0].identifier.name), defaultValue(self.getMemberType(m))) for m in self.memberInfo) + "\n"
             "    };\n"
             "\n"
+            "    let object = if val.is_null_or_undefined() {\n"
+            "        ptr::null()\n"
+            "    } else if val.is_object() {\n"
+            "        val.to_object()\n"
+            "    } else {\n"
+            "        //XXXjdm throw properly here\n"
+            "        return Err(());\n"
+            "    };\n"
             "    unsafe {\n"
-            "      let mut found: JSBool = 0;\n"
-            "      let temp: JSVal = NullValue();\n"
-            "      let isNull = val.is_null_or_undefined();\n"
-            "      if !isNull && val.is_primitive() {\n"
-            "        return Err(()); //XXXjdm throw properly here\n"
-            "        //return Throw(cx, NS_ERROR_XPC_BAD_CONVERT_JS);\n"
-            "      }\n"
-            "\n"
             "${initMembers}\n"
-            "      Ok(result)\n"
             "    }\n"
+            "    Ok(result)\n"
             "  }\n"
             "}").substitute({
                 "selfName": self.makeClassName(d),
@@ -4251,8 +4251,7 @@ class CGDictionary(CGThing):
     def getMemberConversion(self, memberInfo):
         (member, (templateBody, declType,
                   holderType, dealWithOptional, initialValue)) = memberInfo
-        replacements = { "val": "temp",
-                         "valPtr": "&temp",
+        replacements = { "val": "value.unwrap()",
                          "declName": ("result.%s" % self.makeMemberName(member.identifier.name)),
                          # We need a holder name for external interfaces, but
                          # it's scoped down to the conversion so we can just use
@@ -4263,48 +4262,25 @@ class CGDictionary(CGThing):
         if dealWithOptional:
             replacements["declName"] = "(" + replacements["declName"] + ".Value())"
         if member.defaultValue:
-            replacements["haveValue"] = "found != 0"
+            replacements["haveValue"] = "value.is_some()"
 
         propName = member.identifier.name
-        propCheck = ('"%s".to_c_str().with_ref(|s| { JS_HasProperty(cx, val.to_object(), s, &found) })' %
-                     propName)
-        propGet = ('"%s".to_c_str().with_ref(|s| { JS_GetProperty(cx, val.to_object(), s, &temp) })' %
-                   propName)
+        conversion = CGIndenter(
+            CGGeneric(string.Template(templateBody).substitute(replacements)),
+            8).define()
+        if not member.defaultValue:
+            raise TypeError("We don't support dictionary members without a "
+                            "default value.")
 
-        conversionReplacements = {
-            "prop": "(this->%s)" % member.identifier.name,
-            "convert": string.Template(templateBody).substitute(replacements),
-            "propCheck": propCheck,
-            "propGet": propGet
-            }
-        conversion = ("if isNull {\n"
-                      "  found = 0;\n"
-                      "} else if ${propCheck} == 0 {\n"
-                      "  return Err(());\n"
-                      "}\n")
-        if member.defaultValue:
-            conversion += (
-                "if found != 0 {\n"
-                "  if ${propGet} == 0 {\n"
-                "    return Err(());\n"
-                "  }\n"
-                "}\n"
-                "${convert}")
-        else:
-            conversion += (
-                "if found != 0 {\n"
-                "  ${prop}.Construct();\n"
-                "  if ${propGet} == 0 {\n"
-                "    return Err(());\n"
-                "  }\n"
-                "${convert}\n"
-                "}")
-            conversionReplacements["convert"] = CGIndenter(
-                CGGeneric(conversionReplacements["convert"])).define()
+        conversion = (
+            "match get_dictionary_property(cx, object, \"%s\") {\n"
+            "    Err(()) => return Err(()),\n"
+            "    Ok(value) => {\n"
+            "%s\n"
+            "    },\n"
+            "}\n") % (propName, conversion)
 
-        return CGGeneric(
-            string.Template(conversion).substitute(conversionReplacements)
-            )
+        return CGGeneric(conversion)
 
     @staticmethod
     def makeIdName(name):
@@ -4448,6 +4424,7 @@ class CGBindingRoot(CGThing):
             'dom::bindings::utils::{ThrowingConstructor,  unwrap, unwrap_jsmanaged}',
             'dom::bindings::utils::{VoidVal, with_gc_disabled}',
             'dom::bindings::utils::{with_gc_enabled}',
+            'dom::bindings::utils::get_dictionary_property',
             'dom::bindings::trace::JSTraceable',
             'dom::bindings::callback::{CallbackContainer,CallbackInterface}',
             'dom::bindings::callback::{CallSetup,ExceptionHandling}',