Merge the 'new' and 'Init' functions for dictionaries.

This moves the code in callers more in line with conversions for other types
and ensures the default values given to the dictionary fields (as defined by
the defaultValue function in CGDictionary.impl) do not escape the 'new'
method. The new code is also more in line with the code used by the
FromJSValConvertible trait.

This is the first step of my planned rewrite of the dictionary initialization
that will remove the default values entirely and reduce the code
duplication in the 'Init' (now 'new') function.

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

@@ -794,7 +794,6 @@ def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
         assert not isOptional
 
         typeName = CGDictionary.makeDictionaryName(type.inner)
-        selfRef = "${declName}"
 
         declType = CGGeneric(typeName)
 
@@ -806,10 +805,10 @@ def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
         else:
             val = "${val}"
 
-        template = ("%s = %s::new();\n"
-                    "if %s.Init(cx, %s) == 0 {\n"
-                    "  return 0;\n"
-                    "}" % (selfRef, typeName, selfRef, val))
+        template = ("${declName} = match %s::new(cx, %s) {\n"
+                    "  Ok(dictionary) => dictionary,\n"
+                    "  Err(_) => return 0,\n"
+                    "};" % (typeName, val))
 
         return (template, declType, None, False, None)
 
@@ -4143,7 +4142,9 @@ class CGDictionary(CGThing):
                                              descriptorProvider,
                                              isMember=True,
                                              isOptional=(not member.defaultValue),
-                                             defaultValue=member.defaultValue))
+                                             defaultValue=member.defaultValue,
+                                             failureCode="return Err(());",
+                                             exceptionCode="return Err(());"))
             for member in dictionary.members ]
 
     def define(self):
@@ -4172,10 +4173,11 @@ class CGDictionary(CGThing):
     def impl(self):
         d = self.dictionary
         if d.parent:
-            initParent = ("// Per spec, we init the parent's members first\n"
-                          "if self.parent.Init(cx, val) == 0 {\n"
-                          "  return 0;\n"
-                          "}\n")
+            initParent = ("parent: match %s::%s::new(cx, val) {\n"
+                          "  Ok(parent) => parent,\n"
+                          "  Err(_) => return Err(()),\n"
+                          "},\n") % (self.makeModuleName(d.parent),
+                                     self.makeClassName(d.parent))
         else:
             initParent = ""
 
@@ -4196,27 +4198,23 @@ class CGDictionary(CGThing):
 
         return string.Template(
             "impl ${selfName} {\n"
-            "  pub fn new() -> ${selfName} {\n"
-            "    ${selfName} {\n" +
-            (("      parent: %s::%s::new(),\n" % (self.makeModuleName(d.parent),
-                                                  self.makeClassName(d.parent))) if d.parent else "") +
+            "  pub fn new(cx: *JSContext, val: JSVal) -> Result<${selfName}, ()> {\n"
+            "    let mut result = ${selfName} {\n"
+            "${initParent}" +
             "\n".join("      %s: %s," % (self.makeMemberName(m[0].identifier.name), defaultValue(self.getMemberType(m))) for m in self.memberInfo) + "\n"
-            "    }\n"
-            "  }\n"
+            "    };\n"
             "\n"
-            "  pub fn Init(&mut self, cx: *JSContext, val: JSVal) -> JSBool {\n"
             "    unsafe {\n"
-            "${initParent}"
             "      let mut found: JSBool = 0;\n"
             "      let temp: JSVal = NullValue();\n"
             "      let isNull = val.is_null_or_undefined();\n"
             "      if !isNull && val.is_primitive() {\n"
-            "        return 0; //XXXjdm throw properly here\n"
+            "        return Err(()); //XXXjdm throw properly here\n"
             "        //return Throw(cx, NS_ERROR_XPC_BAD_CONVERT_JS);\n"
             "      }\n"
             "\n"
             "${initMembers}\n"
-            "      return 1;\n"
+            "      Ok(result)\n"
             "    }\n"
             "  }\n"
             "}").substitute({
@@ -4255,7 +4253,7 @@ class CGDictionary(CGThing):
                   holderType, dealWithOptional, initialValue)) = memberInfo
         replacements = { "val": "temp",
                          "valPtr": "&temp",
-                         "declName": ("self.%s" % self.makeMemberName(member.identifier.name)),
+                         "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
                          # anything we want.
@@ -4282,13 +4280,13 @@ class CGDictionary(CGThing):
         conversion = ("if isNull {\n"
                       "  found = 0;\n"
                       "} else if ${propCheck} == 0 {\n"
-                      "  return 0;\n"
+                      "  return Err(());\n"
                       "}\n")
         if member.defaultValue:
             conversion += (
                 "if found != 0 {\n"
                 "  if ${propGet} == 0 {\n"
-                "    return 0;\n"
+                "    return Err(());\n"
                 "  }\n"
                 "}\n"
                 "${convert}")
@@ -4297,7 +4295,7 @@ class CGDictionary(CGThing):
                 "if found != 0 {\n"
                 "  ${prop}.Construct();\n"
                 "  if ${propGet} == 0 {\n"
-                "    return 0;\n"
+                "    return Err(());\n"
                 "  }\n"
                 "${convert}\n"
                 "}")