Generate builder if none is written by hand.

toString appends commas.
Improve examples and tests.
Fix double null checking.

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## 0.1.3
+
+- Generate builder if it's not written by hand.
+- Make toString append commas for improved clarity.
+- Improve examples and tests.
+- Fix double null checking.
+
 ## 0.1.2
 
 - Refactor generator to split into logical classes.

built_value/pubspec.yaml

@@ -1,5 +1,5 @@
 name: built_value
-version: 0.1.2
+version: 0.1.3
 description: >
   Value types with builders. This library is the runtime dependency.
 authors:

built_value_generator/lib/src/source_class.dart

@@ -50,12 +50,12 @@ abstract class SourceClass implements Built<SourceClass, SourceClassBuilder> {
           .map((constructor) => constructor.computeNode().toSource()))
       ..valueClassFactories.replace(classElement.constructors
           .where((constructor) => constructor.isFactory)
-          .map((factory) => factory.computeNode().toSource()));
+          .map((factory) => factory.computeNode().toSource()))
+      ..fields.replace(
+          SourceField.fromClassElements(classElement, builderClassElement));
 
     if (hasBuilder) {
       result
-        ..fields.replace(
-            SourceField.fromClassElements(classElement, builderClassElement))
         ..builderClassIsAbstract = builderClassElement.isAbstract
         ..builderClassConstructors.replace(builderClassElement.constructors
             .where((constructor) =>
@@ -127,10 +127,7 @@ abstract class SourceClass implements Built<SourceClass, SourceClassBuilder> {
 
   Iterable<String> _checkBuilderClass() {
     final result = <String>[];
-
-    if (!hasBuilder) {
-      return <String>['Add abstract class: ${name}Builder'];
-    }
+    if (!hasBuilder) return result;
 
     if (!builderClassIsAbstract) {
       result.add('Make builder class abstract.');
@@ -154,6 +151,7 @@ abstract class SourceClass implements Built<SourceClass, SourceClassBuilder> {
   }
 
   Iterable<String> _checkFieldList() {
+    if (!hasBuilder) return <String>[];
     return fields.any((field) => !field.builderFieldExists)
         ? [
             'Make builder have exactly these fields: ' +
@@ -172,6 +170,7 @@ abstract class SourceClass implements Built<SourceClass, SourceClassBuilder> {
     for (final field in fields) {
       result.writeln('final ${field.type} ${field.name};');
     }
+    result.writeln();
 
     if (fields.isEmpty) {
       result.write('_\$$name._() : super._() {');
@@ -184,14 +183,25 @@ abstract class SourceClass implements Built<SourceClass, SourceClassBuilder> {
       result.writeln("if (${field.name} == null) "
           "throw new ArgumentError('null ${field.name}');");
     }
-    result.write('}');
+    result.writeln('}');
+    result.writeln();
 
     result.writeln('factory _\$$name([updates(${name}Builder b)]) '
         '=> (new ${name}Builder()..update(updates)).build();');
+    result.writeln();
+
     result.writeln('$name rebuild(updates(${name}Builder b)) '
         '=> (toBuilder()..update(updates)).build();');
-    result.writeln('_\$${name}Builder toBuilder() '
-        '=> new _\$${name}Builder()..replace(this);');
+    result.writeln();
+
+    if (hasBuilder) {
+      result.writeln('_\$${name}Builder toBuilder() '
+          '=> new _\$${name}Builder()..replace(this);');
+    } else {
+      result.writeln('${name}Builder toBuilder() '
+          '=> new ${name}Builder()..replace(this);');
+    }
+    result.writeln();
 
     result.writeln('bool operator==(other) {');
     result.writeln('  if (other is! $name) return false;');
@@ -205,6 +215,7 @@ abstract class SourceClass implements Built<SourceClass, SourceClassBuilder> {
       result.writeln(';');
     }
     result.writeln('}');
+    result.writeln();
 
     result.writeln('int get hashCode {');
     if (fields.length == 0) {
@@ -215,42 +226,62 @@ abstract class SourceClass implements Built<SourceClass, SourceClassBuilder> {
       result.writeln(']);');
     }
     result.writeln('}');
+    result.writeln();
 
     result.writeln('String toString() {');
     if (fields.length == 0) {
       result.writeln("return '$name {}';");
     } else {
       result.writeln("return '$name {'");
       result.writeln(fields
-          .map((field) => "'${field.name}=\${${field.name}.toString()}\\n'")
+          .map((field) => "'${field.name}=\${${field.name}.toString()},\\n'")
           .join(''));
       result.writeln("'}'");
       result.writeln(';');
     }
     result.writeln('}');
+    result.writeln();
 
     result.writeln('}');
 
-    result.writeln('class _\$${name}Builder extends ${name}Builder {');
-    result.writeln();
-    result.writeln('_\$${name}Builder() : super._();');
+    if (hasBuilder) {
+      result.writeln('class _\$${name}Builder extends ${name}Builder {');
+      result.writeln('_\$${name}Builder() : super._();');
+    } else {
+      result.writeln(
+          'class ${name}Builder implements Builder<$name, ${name}Builder>{');
+      result.writeln('${name}Builder();');
+    }
+
+    if (!hasBuilder) {
+      for (final field in fields) {
+        // Nested builders are initialized to an empty builder, unless the
+        // field is nullable.
+        if (field.isNestedBuilder && !field.isNullable) {
+          result.writeln('${field.typeInBuilder} ${field.name} = new ${field.typeInBuilder}();');
+        } else {
+          result.writeln('${field.typeInBuilder} ${field.name};');
+        }
+      }
+      result.writeln();
+    }
 
     result.writeln('void replace(${name} other) {');
     result.writeln((fields.map((field) {
+      final superOrThis = hasBuilder ? 'super' : 'this';
       return field.isNestedBuilder
-          ? 'super.${field.name} = other.${field.name}?.toBuilder();'
-          : 'super.${field.name} = other.${field.name};';
+          ? '$superOrThis.${field.name} = other.${field.name}?.toBuilder();'
+          : '$superOrThis.${field.name} = other.${field.name};';
     }))
         .join('\n'));
     result.writeln('}');
+    result.writeln();
 
     result.writeln('void update(updates(${name}Builder b)) {'
         ' if (updates != null) updates(this); }');
+    result.writeln();
+
     result.writeln('$name build() {');
-    for (final field in fields.where((field) => !field.isNullable)) {
-      result.writeln("if (${field.name} == null) "
-          "throw new ArgumentError('null ${field.name}');");
-    }
     result.writeln('return new _\$$name._(');
     result.write(fields.map((field) {
       return field.isNestedBuilder

built_value_generator/lib/src/source_field.dart

@@ -5,19 +5,27 @@
 library built_value_generator.source_field;
 
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/type.dart';
 import 'package:built_collection/built_collection.dart';
 import 'package:built_value/built_value.dart';
 
 part 'source_field.g.dart';
 
+BuiltSet<String> _builtCollectionNames = new BuiltSet<String>([
+  'BuiltList',
+  'BuiltListMultimap',
+  'BuiltMap',
+  'BuiltSet',
+  'BuiltSetMultimap',
+]);
+
 abstract class SourceField implements Built<SourceField, SourceFieldBuilder> {
   String get name;
   String get type;
   bool get isGetter;
   bool get isNullable;
   bool get builderFieldExists;
   bool get builderFieldIsNormalField;
-  @nullable
   String get typeInBuilder;
   bool get isNestedBuilder;
 
@@ -26,22 +34,35 @@ abstract class SourceField implements Built<SourceField, SourceFieldBuilder> {
 
   factory SourceField.fromFieldElements(
       FieldElement fieldElement, FieldElement builderFieldElement) {
-    return new SourceField((b) => b
+    final result = new SourceFieldBuilder();
+    final builderFieldExists = builderFieldElement != null;
+    final type = fieldElement.getter.returnType.displayName;
+    result
       ..name = fieldElement.displayName
-      ..type = fieldElement.getter.returnType.displayName
-      ..typeInBuilder = builderFieldElement?.getter?.returnType?.displayName
+      ..type = type
       ..isGetter =
           fieldElement.getter != null && !fieldElement.getter.isSynthetic
       ..isNullable = fieldElement.getter.metadata.any(
-          (metadata) => metadata.constantValue.toStringValue() == 'nullable')
-      ..builderFieldExists = builderFieldElement != null
-      ..builderFieldIsNormalField = builderFieldElement != null &&
-          builderFieldElement.getter != null &&
-          !builderFieldElement.getter.isAbstract &&
-          builderFieldElement.getter.isSynthetic
-      ..isNestedBuilder = builderFieldElement?.getter?.returnType?.displayName
-              ?.contains('Builder') ??
-          false);
+          (metadata) => metadata.constantValue.toStringValue() == 'nullable');
+
+    if (builderFieldExists) {
+      result
+        ..builderFieldExists = true
+        ..builderFieldIsNormalField = builderFieldElement.getter != null &&
+            !builderFieldElement.getter.isAbstract &&
+            builderFieldElement.getter.isSynthetic
+        ..typeInBuilder = builderFieldElement.getter?.returnType?.displayName
+        ..isNestedBuilder = builderFieldElement.getter?.returnType?.displayName
+                ?.contains('Builder') ??
+            false;
+    } else {
+      result
+        ..builderFieldExists = false
+        ..builderFieldIsNormalField = true
+        ..typeInBuilder = _toBuilderType(fieldElement.getter.returnType)
+        ..isNestedBuilder = _needsNestedBuilder(fieldElement.getter.returnType);
+    }
+    return result.build();
   }
 
   static BuiltList<SourceField> fromClassElements(
@@ -52,14 +73,42 @@ abstract class SourceField implements Built<SourceField, SourceFieldBuilder> {
       if (!field.isStatic &&
           field.getter != null &&
           (field.getter.isAbstract || field.getter.isSynthetic)) {
-        final builderField = builderClassElement.getField(field.name);
+        final builderField = builderClassElement?.getField(field.name);
         result.add(new SourceField.fromFieldElements(field, builderField));
       }
     }
 
     return result.build();
   }
 
+  static bool _needsNestedBuilder(DartType type) {
+    return _isBuiltValue(type) || _isBuiltCollection(type);
+  }
+
+  static bool _isBuiltValue(DartType type) {
+    if (type.element is! ClassElement) return false;
+    return (type.element as ClassElement)
+        .allSupertypes
+        .any((interfaceType) => interfaceType.name == 'Built');
+  }
+
+  static bool _isBuiltCollection(DartType type) {
+    return _builtCollectionNames
+        .any((name) => type.displayName.startsWith('${name}<'));
+  }
+
+  static String _toBuilderType(DartType type) {
+    if (_isBuiltCollection(type)) {
+      return type.displayName
+          .replaceFirst('Built', '')
+          .replaceFirst('<', 'Builder<');
+    } else if (_isBuiltValue(type)) {
+      return '${type.displayName}Builder';
+    } else {
+      return type.displayName;
+    }
+  }
+
   Iterable<String> computeErrors() {
     final result = <String>[];