feat: copyWith generation (#7)

examples/embedded/user.go.dart

@@ -1,9 +1,11 @@
 // ignore_for_file: always_use_package_imports
+import 'package:copy_with_extension/copy_with_extension.dart';
 import 'package:equatable/equatable.dart';
 import 'package:json_annotation/json_annotation.dart';
 
 part 'user.go.g.dart';
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true)
 class Address extends Equatable {
 	@JsonKey(name: "street_line_1")final String street;
@@ -28,6 +30,7 @@ class Address extends Equatable {
 	];
 }
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true)
 class Profile extends Equatable {
 	@JsonKey(name: "ID")final int id;
@@ -61,6 +64,7 @@ class Profile extends Equatable {
 	];
 }
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true)
 class User extends Equatable {
 	@JsonKey(name: "ID")final int id;

examples/everything/everything.go.dart

@@ -1,9 +1,11 @@
 // ignore_for_file: always_use_package_imports
+import 'package:copy_with_extension/copy_with_extension.dart';
 import 'package:equatable/equatable.dart';
 import 'package:json_annotation/json_annotation.dart';
 
 part 'everything.go.g.dart';
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true)
 class Child extends Equatable {
 	final int id;
@@ -38,6 +40,7 @@ class Empty extends Equatable {
 	List<Object?> get props => [];
 }
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true)
 class Parent extends Equatable {
 	final String id;

examples/firestore/firestore.go.dart

@@ -1,5 +1,6 @@
 // ignore_for_file: always_use_package_imports
 import 'package:cloud_firestore/cloud_firestore.dart';
+import 'package:copy_with_extension/copy_with_extension.dart';
 import 'package:equatable/equatable.dart';
 import 'package:json_annotation/json_annotation.dart';
 
@@ -15,6 +16,7 @@ class _TimestampConverter implements JsonConverter<DateTime, Timestamp> {
   Timestamp toJson(DateTime object) => Timestamp.fromDate(object);
 }
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true)
 @_TimestampConverter()
 class User extends Equatable {

examples/generics/generics.go.dart

@@ -1,9 +1,11 @@
 // ignore_for_file: always_use_package_imports
+import 'package:copy_with_extension/copy_with_extension.dart';
 import 'package:equatable/equatable.dart';
 import 'package:json_annotation/json_annotation.dart';
 
 part 'generics.go.g.dart';
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true)
 class Instance extends Equatable {
 	final Map<String, int> m;
@@ -22,6 +24,7 @@ class Instance extends Equatable {
 	];
 }
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true, genericArgumentFactories: true)
 class KeyValuePair<TKey, TValue> extends Equatable {
 	final TKey key;
@@ -43,6 +46,7 @@ class KeyValuePair<TKey, TValue> extends Equatable {
 	];
 }
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true, genericArgumentFactories: true)
 class Map<TKey, TValue> extends Equatable {
 	@JsonKey(defaultValue: <List<KeyValuePair<TKey, TValue>>>[])final List<KeyValuePair<TKey, TValue>> items;

examples/multipackage/multipackage.go.dart

@@ -1,5 +1,6 @@
 // ignore_for_file: always_use_package_imports
 import 'package:cloud_firestore/cloud_firestore.dart';
+import 'package:copy_with_extension/copy_with_extension.dart';
 import 'package:equatable/equatable.dart';
 import 'package:json_annotation/json_annotation.dart';
 
@@ -15,6 +16,7 @@ class _TimestampConverter implements JsonConverter<DateTime, Timestamp> {
   Timestamp toJson(DateTime object) => Timestamp.fromDate(object);
 }
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true)
 @_TimestampConverter()
 class Outer extends Equatable {

examples/user/user.go.dart

@@ -1,9 +1,11 @@
 // ignore_for_file: always_use_package_imports
+import 'package:copy_with_extension/copy_with_extension.dart';
 import 'package:equatable/equatable.dart';
 import 'package:json_annotation/json_annotation.dart';
 
 part 'user.go.g.dart';
 
+@CopyWith()
 @JsonSerializable(explicitToJson: true)
 class User extends Equatable {
 	@JsonKey(name: "ID")final int id;

generator/class.go

@@ -33,19 +33,17 @@ func extractFields(st *types.Struct) []fieldProjection {
 	return fields
 }
 
-func generateFields(wr io.Writer, st *types.Struct, registry *format.TypeFormatterRegistry, mode options.Mode) {
-	fields := extractFields(st)
+func generateFields(wr io.Writer, registry *format.TypeFormatterRegistry, mode options.Mode, fields []fieldProjection) {
 	for _, field := range fields {
 		generateFieldDeclaration(wr, field.field, field.tag, registry, mode)
 		fmt.Fprintln(wr, ";")
 	}
 	fmt.Fprintln(wr)
 }
 
-func generateConstructor(wr io.Writer, ts *types.TypeName, st *types.Struct, registry *format.TypeFormatterRegistry) {
+func generateConstructor(wr io.Writer, ts *types.TypeName, registry *format.TypeFormatterRegistry, fields []fieldProjection) {
 	fmt.Fprintf(wr, "const %s(", ts.Name())
 
-	fields := extractFields(st)
 	if len(fields) > 0 {
 		fmt.Fprintln(wr, "{")
 		for _, field := range fields {
@@ -60,15 +58,14 @@ func generateConstructor(wr io.Writer, ts *types.TypeName, st *types.Struct, reg
 	fmt.Fprintln(wr)
 }
 
-func generateEquatable(wr io.Writer, st *types.Struct) {
+func generateEquatable(wr io.Writer, fields []fieldProjection) {
 	fmt.Fprintln(wr, "@override")
 	fmt.Fprint(wr, "List<Object?> get props => [")
-	if st.NumFields() > 0 {
+	if len(fields) > 0 {
 		fmt.Fprintln(wr)
 	}
 
 	iwr := indent.NewWriter(wr, "\t")
-	fields := extractFields(st)
 	for _, field := range fields {
 		fmt.Fprintf(iwr, "%s,\n", format.GetFieldName(field.field))
 	}
@@ -82,6 +79,11 @@ func generateDartClass(outputFile io.Writer, ts *types.TypeName, st *types.Struc
 		panic(fmt.Sprintf("expected StructFormatter, got %T", registry.GetTypeFormatter(ts.Type())))
 	}
 
+	fields := extractFields(st)
+
+	if len(fields) > 0 {
+		fmt.Fprintln(outputFile, "@CopyWith()")
+	}
 	fmt.Fprintln(outputFile, formatter.Annotation(ts))
 	if mode == options.Firestore {
 		fmt.Fprintln(outputFile, "@_TimestampConverter()")
@@ -90,11 +92,11 @@ func generateDartClass(outputFile io.Writer, ts *types.TypeName, st *types.Struc
 
 	wr := indent.NewWriter(outputFile, "\t")
 
-	generateFields(wr, st, registry, mode)
-	generateConstructor(wr, ts, st, registry)
+	generateFields(wr, registry, mode, fields)
+	generateConstructor(wr, ts, registry, fields)
 	fmt.Fprint(wr, formatter.Serialization(ts))
 	fmt.Fprintln(wr, formatter.Deserialization(ts))
-	generateEquatable(wr, st)
+	generateEquatable(wr, fields)
 
 	fmt.Fprintln(outputFile, "}")
 	fmt.Fprintln(outputFile, "")

generator/generator.go

@@ -27,6 +27,7 @@ func generateHeader(pkg *packages.Package, wr io.Writer, mode options.Mode, impo
 		fmt.Fprint(wr, "import 'package:cloud_firestore/cloud_firestore.dart';\n")
 	}
 
+	fmt.Fprint(wr, "import 'package:copy_with_extension/copy_with_extension.dart';\n")
 	fmt.Fprint(wr, "import 'package:equatable/equatable.dart';\n")
 	fmt.Fprint(wr, "import 'package:json_annotation/json_annotation.dart';\n")
 	for _, imp := range imports {