chore(reducers): reduce object copying in iterators

Author: kuhe

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/StructuredMemberWriter.java

@@ -220,12 +220,13 @@ private void writeMapFilterSensitiveLog(TypeScriptWriter writer, MemberShape map
             String valueParam = "value"; // value of the Object.entries() key-value pair
 
             // Reducer is common to all shapes.
-            writer.openBlock("Object.entries($L).reduce(($L: any, [$L, $L]: [string, $T]) => ({", "}), {})",
+            writer.openBlock("Object.entries($L).reduce(($L: any, [$L, $L]: [string, $T]) => (", "), {})",
                 mapParam, accParam, keyParam, valueParam, symbolProvider.toSymbol(mapMember), () -> {
-                    writer.write("...$L,", accParam);
-                    writer.openBlock("[$L]: ", ",", keyParam, () -> {
+                    writer.openBlock("$L[$L] =", "", accParam, keyParam, () -> {
                         writeMemberFilterSensitiveLog(writer, mapMember, valueParam);
+                        writer.writeInline(",");
                     });
+                    writer.write(accParam);
                 }
             );
         }

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/HttpBindingProtocolGenerator.java

@@ -981,15 +981,15 @@ private void writePrefixHeaders(GenerationContext context, HttpBinding binding)
         // Iterate through each entry in the member.
         writer.openBlock("...($1L !== undefined) && Object.keys($1L).reduce(", "),", memberLocation,
             () -> {
-                writer.openBlock("(acc: any, suffix: string) => ({", "}), {}",
+                writer.openBlock("(acc: any, suffix: string) => {", "}, {}",
                     () -> {
                         // Use a ! since we already validated the input member is defined above.
                         String headerValue = getInputValue(context, binding.getLocation(),
                                 memberLocation + "![suffix]", binding.getMember(), target);
-                        writer.write("...acc,");
                         // Append the prefix to key.
-                        writer.write("[`$L$${suffix.toLowerCase()}`]: $L,",
+                        writer.write("acc[`$L$${suffix.toLowerCase()}`] = $L;",
                                 binding.getLocationName().toLowerCase(Locale.US), headerValue);
+                        writer.write("return acc;");
                     });
             }
         );
@@ -1348,10 +1348,10 @@ private String getMapInputParam(
         String valueString = getInputValue(context, bindingType, "value", mapMember,
                 model.expectShape(mapMember.getTarget()));
         return "Object.entries(" + dataSource + " || {}).reduce("
-            + "(acc: any, [key, value]: [string, " + symbolProvider.toSymbol(mapMember) + "]) => ({"
-            +   "...acc,"
-            +   "[key]: " + valueString + ","
-            + "}), {})";
+            + "(acc: any, [key, value]: [string, " + symbolProvider.toSymbol(mapMember) + "]) => {"
+            +   "acc[key] = " + valueString + ";"
+            +   "return acc;"
+            + "}, {})";
     }
 
     /**

smithy-typescript-codegen/src/test/java/software/amazon/smithy/typescript/codegen/StructureGeneratorTest.java

@@ -418,12 +418,12 @@ public void callsFilterForMapWithStructureWithSensitiveData() {
                             "export const GetFooInputFilterSensitiveLog = (obj: GetFooInput): any => ({\n"
                             + "  ...obj,\n"
                             + "  ...(obj.foo && { foo:\n"
-                            + "    Object.entries(obj.foo).reduce((acc: any, [key, value]: [string, User]) => ({\n"
-                            + "      ...acc,\n"
-                            + "      [key]:\n"
+                            + "    Object.entries(obj.foo).reduce((acc: any, [key, value]: [string, User]) => (\n"
+                            + "      acc[key] =\n"
                             + "        UserFilterSensitiveLog(value)\n"
-                            + "      ,\n"
-                            + "    }), {})\n"
+                            + "        ,\n"
+                            + "      acc\n"
+                            + "    ), {})\n"
                             + "  }),\n"
                             + "})");
     }
@@ -445,12 +445,12 @@ public void callsFilterForMapWithUnionWithSensitiveData() {
                         "export const GetFooInputFilterSensitiveLog = (obj: GetFooInput): any => ({\n"
                         + "  ...obj,\n"
                         + "  ...(obj.foo && { foo:\n"
-                        + "    Object.entries(obj.foo).reduce((acc: any, [key, value]: [string, TestUnion]) => ({\n"
-                        + "      ...acc,\n"
-                        + "      [key]:\n"
+                        + "    Object.entries(obj.foo).reduce((acc: any, [key, value]: [string, TestUnion]) => (\n"
+                        + "      acc[key] =\n"
                         + "        TestUnionFilterSensitiveLog(value)\n"
-                        + "      ,\n"
-                        + "    }), {})\n"
+                        + "        ,\n"
+                        + "      acc\n"
+                        + "    ), {})\n"
                         + "  }),\n"
                         + "})");
     }