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// Copyright (c) 2016, 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.
import 'package:protobuf/meta.dart';
import 'package:protoc_plugin/src/dart_options.pb.dart';
import 'package:protoc_plugin/src/descriptor.pb.dart';
/// A Dart function called on each item added to a repeated list
/// to check its type and range.
const checkItem = '\$checkItem';
/// The Dart member names in a GeneratedMessage subclass for one protobuf field.
class MemberNames {
/// The descriptor of the field these member names apply to.
final FieldDescriptorProto descriptor;
/// The index of this field in MessageGenerator.fieldList.
/// The same index will be stored in FieldInfo.index.
final int index;
/// Identifier for generated getters/setters.
final String fieldName;
/// Identifier for the generated hasX() method, without braces.
/// `null` for repeated fields.
final String hasMethodName;
/// Identifier for the generated clearX() method, without braces.
/// `null` for repeated fields.
final String clearMethodName;
MemberNames(this.descriptor, this.index, this.fieldName,
{this.hasMethodName, this.clearMethodName});
/// Move any initial underscores in [input] to the end.
/// According to the spec identifiers cannot start with _, but it seems to be
/// accepted by protoc.
/// These identifiers are private in Dart, so they have to be transformed.
String avoidInitialUnderscore(String input) {
while (input.startsWith('_')) {
input = '${input.substring(1)}_';
return input;
/// Returns [input] surrounded by single quotes and with all '$'s escaped.
String singleQuote(String input) {
return "'${input.replaceAll(r'$', r'\$')}'";
/// Chooses the Dart name of an extension.
String extensionName(FieldDescriptorProto descriptor, Set<String> usedNames) {
return _unusedMemberNames(descriptor, null, usedNames).fieldName;
Iterable<String> extensionSuffixes() sync* {
yield "Ext";
int i = 2;
while (true) {
yield '$i';
/// Replaces all characters in [imput] that are not valid in a dart identifier
/// with _.
/// This function does not take care of leading underscores.
String legalDartIdentifier(String imput) {
return imput.replaceAll(new RegExp(r'[^a-zA-Z0-9$_]'), '_');
/// Chooses the name of the Dart class holding top-level extensions.
String extensionClassName(
FileDescriptorProto descriptor, Set<String> usedNames) {
String s = avoidInitialUnderscore(
String candidate = '${s[0].toUpperCase()}${s.substring(1)}';
return disambiguateName(candidate, usedNames, extensionSuffixes());
String _fileNameWithoutExtension(FileDescriptorProto descriptor) {
Uri path = new Uri.file(;
String fileName = path.pathSegments.last;
int dot = fileName.lastIndexOf(".");
return dot == -1 ? fileName : fileName.substring(0, dot);
// Exception thrown when a field has an invalid 'dart_name' option.
class DartNameOptionException implements Exception {
final String message;
String toString() => "$message";
/// Returns a [name] that is not contained in [usedNames] by suffixing it with
/// the first possible suffix from [suffixes].
/// The chosen name is added to [usedNames].
/// If [variants] is given, all the variants of a name must be available before
/// that name is chosen, and all the chosen variants will be added to
/// [usedNames].
/// The returned name is that, which will generate the accepted variants.
String disambiguateName(
String name, Set<String> usedNames, Iterable<String> suffixes,
{List<String> Function(String candidate) generateVariants}) {
generateVariants ??= (String name) => <String>[name];
bool allVariantsAvailable(List<String> variants) {
return variants.every((String variant) => !usedNames.contains(variant));
String usedSuffix = '';
List<String> candidateVariants = generateVariants(name);
if (!allVariantsAvailable(candidateVariants)) {
for (String suffix in suffixes) {
candidateVariants = generateVariants('$name$suffix');
if (allVariantsAvailable(candidateVariants)) {
usedSuffix = suffix;
return '$name$usedSuffix';
Iterable<String> defaultSuffixes() sync* {
yield '_';
int i = 0;
while (true) {
yield ('_$i');
/// Chooses the name of the Dart class to generate for a proto message or enum.
/// For a nested message or enum, [parent] should be provided
/// with the name of the Dart class for the immediate parent.
String messageOrEnumClassName(String descriptorName, Set<String> usedNames,
{String parent = ''}) {
if (parent != '') {
descriptorName = '${parent}_${descriptorName}';
return disambiguateName(
avoidInitialUnderscore(descriptorName), usedNames, defaultSuffixes());
/// Returns the set of names reserved by the ProtobufEnum class and its
/// generated subclasses.
Set<String> get reservedEnumNames => new Set<String>()
Iterable<String> enumSuffixes() sync* {
String s = '_';
while (true) {
yield s;
s += '_';
/// Chooses the GeneratedMessage member names for each field.
/// Additional names to avoid can be supplied using [reserved].
/// (This should only be used for mixins.)
/// Returns a map from the field name in the .proto file to its
/// corresponding MemberNames.
/// Throws [DartNameOptionException] if a field has this option and
/// it's set to an invalid name.
Map<String, MemberNames> messageFieldNames(DescriptorProto descriptor,
{Iterable<String> reserved = const []}) {
var sorted = new List<FieldDescriptorProto>.from(descriptor.field)
..sort((FieldDescriptorProto a, FieldDescriptorProto b) {
if (a.number < b.number) return -1;
if (a.number > b.number) return 1;
throw "multiple fields defined for tag ${a.number} in ${}";
// Choose indexes first, based on their position in the sorted list.
var indexes = <String, int>{};
for (var field in sorted) {
var index = indexes.length;
indexes[] = index;
var existingNames = new Set<String>()
var memberNames = <String, MemberNames>{};
void takeNames(MemberNames chosen) {
memberNames[] = chosen;
if (chosen.hasMethodName != null) {
if (chosen.clearMethodName != null) {
// Handle fields with a dart_name option.
// They have higher priority than automatically chosen names.
// Explicitly setting a name that's already taken is a build error.
for (var field in sorted) {
if (_nameOption(field).isNotEmpty) {
descriptor, field, indexes[], existingNames));
// Then do other fields.
// They are automatically renamed until we find something unused.
for (var field in sorted) {
if (_nameOption(field).isEmpty) {
var index = indexes[];
takeNames(_unusedMemberNames(field, index, existingNames));
// Return a map with entries in sorted order.
var result = <String, MemberNames>{};
for (var field in sorted) {
result[] = memberNames[];
return result;
/// Chooses the member names for a field that has the 'dart_name' option.
/// If the explicitly-set Dart name is already taken, throw an exception.
/// (Fails the build.)
MemberNames _memberNamesFromOption(DescriptorProto message,
FieldDescriptorProto field, int index, Set<String> existingNames) {
// TODO(skybrian): provide more context in errors (filename).
var where = "${}.${}";
void checkAvailable(String name) {
if (existingNames.contains(name)) {
throw new DartNameOptionException(
"$where: dart_name option is invalid: '$name' is already used");
var name = _nameOption(field);
if (name.isEmpty) {
throw new ArgumentError("field doesn't have dart_name option");
if (!_isDartFieldName(name)) {
throw new DartNameOptionException("$where: dart_name option is invalid: "
"'$name' is not a valid Dart field name");
if (_isRepeated(field)) {
return new MemberNames(field, index, name);
String hasMethod = "has${_capitalize(name)}";
String clearMethod = "clear${_capitalize(name)}";
return new MemberNames(field, index, name,
hasMethodName: hasMethod, clearMethodName: clearMethod);
Iterable<String> _memberNamesSuffix(int number) sync* {
String suffix = '_$number';
while (true) {
yield suffix;
suffix = '${suffix}_$number';
MemberNames _unusedMemberNames(
FieldDescriptorProto field, int index, Set<String> existingNames) {
if (_isRepeated(field)) {
return new MemberNames(
existingNames, _memberNamesSuffix(field.number)));
List<String> generateNameVariants(String name) {
return [
String name = disambiguateName(_fieldMethodSuffix(field), existingNames,
generateVariants: generateNameVariants);
return new MemberNames(field, index, _defaultFieldName(name),
hasMethodName: _defaultHasMethodName(name),
clearMethodName: _defaultClearMethodName(name));
/// The name to use by default for the Dart getter and setter.
/// (A suffix will be added if there is a conflict.)
String _defaultFieldName(String fieldMethodSuffix) {
return '${fieldMethodSuffix[0].toLowerCase()}${fieldMethodSuffix.substring(1)}';
String _defaultHasMethodName(String fieldMethodSuffix) =>
String _defaultClearMethodName(String fieldMethodSuffix) =>
/// The suffix to use for this field in Dart method names.
/// (It should be camelcase and begin with an uppercase letter.)
String _fieldMethodSuffix(FieldDescriptorProto field) {
var name = _nameOption(field);
if (name.isNotEmpty) return _capitalize(name);
if (field.type != FieldDescriptorProto_Type.TYPE_GROUP) {
return _underscoresToCamelCase(;
// For groups, use capitalization of 'typeName' rather than 'name'.
name = field.typeName;
int index = name.lastIndexOf('.');
if (index != -1) {
name = name.substring(index + 1);
return _underscoresToCamelCase(name);
String _underscoresToCamelCase(s) => s.split('_').map(_capitalize).join('');
String _capitalize(s) =>
s.isEmpty ? s : '${s[0].toUpperCase()}${s.substring(1)}';
bool _isRepeated(FieldDescriptorProto field) =>
field.label == FieldDescriptorProto_Label.LABEL_REPEATED;
String _nameOption(FieldDescriptorProto field) =>
bool _isDartFieldName(name) => name.startsWith(_dartFieldNameExpr);
final _dartFieldNameExpr = new RegExp(r'^[a-z]\w+$');
/// Names that would collide with capitalized core Dart names as top-level
/// identifiers.
final List<String> toplevelReservedCapitalizedNames = const <String>[
final List<String> reservedMemberNames = <String>[]
final List<String> forbiddenExtensionNames = <String>[]
// List of Dart language reserved words in names which cannot be used in a
// subclass of GeneratedMessage.
const List<String> _dartReservedWords = const [
// List of names used in the generated message classes.
// This is in addition to GeneratedMessage_reservedNames, which are names from
// the base GeneratedMessage class determined by reflection.
const _generatedMessageNames = const <String>[
// List of names used in the generated enum classes.
// This is in addition to ProtobufEnum_reservedNames, which are names from the
// base ProtobufEnum class determined by reflection.
const _protobufEnumNames = const <String>[