Make certain generated constructor parameters optional.

pkg/analysis_server/tool/spec/codegen_dart_protocol.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library codegen.protocol;
 
 import 'dart:convert';
 
 import 'api.dart';
 import 'codegen_tools.dart';
@@ skipping 176 matching lines @@
  */
 class CodegenProtocolVisitor extends HierarchicalApiVisitor with CodeGenerator {
   /**
    * Type references in the spec that are named something else in Dart.
    */
   static const Map<String, String> _typeRenames = const {
     'object': 'Object',
   };
 
   /**
+   * Class members for which the constructor argument should be optional, even
+   * if the member is not an optional part of the protocol.  For list types,
+   * the constructor will default the member to the empty list.
+   */
+  static const Map<String, List<String>> _optionalConstructorArguments = const {
+    'SourceFileEdit': const ['edits'],
+    'TypeHierarchyItem': const ['interfaces', 'mixins', 'subclasses']
+  };
+
+  /**
    * Visitor used to produce doc comments.
    */
   final ToHtmlVisitor toHtmlVisitor;
 
   /**
    * Types implied by the API.  This includes types explicitly named in the
    * API as well as those implied by the definitions of requests, responses,
    * notifications, etc.
    */
   final Map<String, ImpliedType> impliedTypes;
@@ skipping 257 matching lines @@
    */
   void emitObjectConstructor(TypeObject type, String className) {
     List<String> args = <String>[];
     List<String> optionalArgs = <String>[];
     List<CodegenCallback> extraInitCode = <CodegenCallback>[];
     for (TypeObjectField field in type.fields) {
       if (field.value != null) {
         continue;
       }
       String arg = 'this.${field.name}';
-      if (field.optional) {
+      if (isOptionalConstructorArg(className, field)) {
         optionalArgs.add(arg);
         TypeDecl fieldType = field.type;
         if (fieldType is TypeList) {
           extraInitCode.add(() {
             writeln('if (${field.name} == null) {');
             indent(() {
               writeln('${field.name} = <${dartType(fieldType.itemType)}>[];');
             });
             writeln('}');
           });
@@ skipping 13 matching lines @@
       indent(() {
         for (CodegenCallback callback in extraInitCode) {
           callback();
         }
       });
       writeln('}');
     }
   }
 
   /**
+   * True if the constructor argument for the given field should be optional.
+   */
+  bool isOptionalConstructorArg(String className, TypeObjectField field) {
+    if (field.optional) {
+      return true;
+    }
+    List<String> forceOptional = _optionalConstructorArguments[className];
+    if (forceOptional != null && forceOptional.contains(field.name)) {
+      return true;
+    }
+    return false;
+  }
+
+  /**
    * Emit the toJson() code for an object class.
    */
   void emitToJsonMember(TypeObject type) {
     writeln('Map<String, dynamic> toJson() {');
     indent(() {
       writeln('Map<String, dynamic> result = {};');
       for (TypeObjectField field in type.fields) {
         String fieldNameString = literalString(field.name);
         if (field.value != null) {
           writeln('result[$fieldNameString] = ${literalString(field.value)};');
@@ skipping 287 matching lines @@
           if (field.value != null) {
             String valueString = literalString(field.value);
             writeln('if ($fieldAccessor != $valueString) {');
             indent(() {
               writeln(
                   'throw jsonDecoder.mismatch(jsonPath, "equal " + $valueString);');
             });
             writeln('}');
             continue;
           }
-          if (field.optional) {
+          if (isOptionalConstructorArg(className, field)) {
             optionalArgs.add('${field.name}: ${field.name}');
           } else {
             args.add(field.name);
           }
           TypeDecl fieldType = field.type;
           String fieldDartType = dartType(fieldType);
           writeln('$fieldDartType ${field.name};');
           writeln('if (json.containsKey($fieldNameString)) {');
           indent(() {
             String toJson = fromJsonCode(fieldType).asSnippet(jsonPath,
@@ skipping 260 matching lines @@
   CodegenProtocolVisitor visitor = new CodegenProtocolVisitor(readApi());
   return visitor.collectCode(visitor.visitApi);
 });
 
 /**
  * Translate spec_input.html into protocol_matchers.dart.
  */
 main() {
   target.generate();
 }