Implement proto text format generator (#1080)

This syncs cl/816776257, not my code.

Only text format generation is implemented. We don't parse the text format yet.

(Related issue: #125)

Author: osa1

protobuf/CHANGELOG.md

@@ -1,3 +1,13 @@
+## 5.2.0
+
+* New `GeneratedMessage` extension methods `toTextFormat` and `writeTextFormat`
+  added to convert the message into the [official protocol buffers text
+  format][text format]. ([#1080], [#125])
+
+[text format]: https://protobuf.dev/reference/protobuf/textformat-spec/
+[#1080]: https://github.com/google/protobuf.dart/pull/1080
+[#125]: https://github.com/google/protobuf.dart/issues/125
+
 ## 5.1.0
 
 * Update default size limit of `CodedBufferReader` from 67,108,864 bytes to

protobuf/lib/src/protobuf/field_set.dart

@@ -727,6 +727,100 @@ class FieldSet {
     }
   }
 
+  /// Writes the text proto string representation of the message.
+  /// Spec: https://protobuf.dev/reference/protobuf/textformat-spec/
+  void writeTextFormat(StringSink out) {
+    _writeTextFormat(out, 0);
+  }
+
+  void _writeTextFormat(StringSink out, int initialIndentLevel) {
+    void writeIndent(int indentLevel) {
+      for (var i = 0; i < indentLevel; i++) {
+        out.writeCharCode(32);
+        out.writeCharCode(32);
+      }
+    }
+
+    void renderValue(String key, dynamic value, int indentLevel) {
+      writeIndent(indentLevel);
+      if (value is GeneratedMessage) {
+        out.write('$key {\n');
+        value._fieldSet._writeTextFormat(out, indentLevel + 1);
+        writeIndent(indentLevel);
+        out.write('}\n');
+      } else if (value is MapEntry) {
+        out.write('$key {\n');
+        renderValue('key', value.key, indentLevel + 1);
+        renderValue('value', value.value, indentLevel + 1);
+        writeIndent(indentLevel);
+        out.write('}\n');
+      } else if (value is String) {
+        out.write('$key: "${escapeString(value)}"\n');
+      } else if (value is Map) {
+        out.write('$key {\n');
+        for (final entry in value.entries) {
+          renderValue(entry.key, entry.value, indentLevel + 1);
+        }
+        writeIndent(indentLevel);
+        out.write('}\n');
+        // Bytes are represented as a List<int> in Dart protobuf.
+      } else if (value is List<int>) {
+        out.write('$key: "');
+        escapeBytes(value, out);
+        out.write('"\n');
+      } else {
+        // Writes the primitive value as a string.
+        out.write('$key: $value\n');
+      }
+    }
+
+    void writeFieldValue(String name, dynamic fieldValue) {
+      if (fieldValue is PbList) {
+        for (final value in fieldValue) {
+          renderValue(name, value, initialIndentLevel);
+        }
+      } else if (fieldValue is PbMap) {
+        for (final entry in fieldValue.entries) {
+          renderValue(name, entry, initialIndentLevel);
+        }
+      } else {
+        renderValue(name, fieldValue, initialIndentLevel);
+      }
+    }
+
+    for (final fi in _infosSortedByTag) {
+      if (_hasField(fi.tagNumber)) {
+        writeFieldValue(
+          fi.name == '' ? fi.tagNumber.toString() : fi.protoName,
+          _values[fi.index!],
+        );
+      }
+    }
+
+    final extensions = _extensions;
+    if (extensions != null) {
+      extensions._info.keys.toList()
+        ..sort()
+        ..forEach((int tagNumber) {
+          if (_hasField(tagNumber)) {
+            writeFieldValue(
+              '[${extensions._info[tagNumber]!.name}]',
+              extensions._values[tagNumber],
+            );
+          }
+        });
+    }
+
+    _unknownFields?.writeTextFormat(out, initialIndentLevel);
+
+    final unknownJsonData = _unknownJsonData;
+    if (unknownJsonData != null) {
+      for (final entry in unknownJsonData.entries) {
+        renderValue(entry.key, entry.value, initialIndentLevel);
+      }
+    }
+  }
+
   /// Merges the contents of the [other] into this message.
   ///
   /// Singular fields that are set in [other] overwrite the corresponding fields

protobuf/lib/src/protobuf/generated_message.dart

@@ -616,3 +616,21 @@ extension GeneratedMessageGenericExtensions<T extends GeneratedMessage> on T {
 extension GeneratedMessageInternalExtension on GeneratedMessage {
   FieldSet get fieldSet => _fieldSet;
 }
+
+extension TextFormatExtension on GeneratedMessage {
+  /// Returns a TextFormat [String] representation of this message.
+  ///
+  /// Spec: https://protobuf.dev/reference/protobuf/textformat-spec/
+  String toTextFormat() {
+    final out = StringBuffer();
+    writeTextFormat(out);
+    return out.toString();
+  }
+
+  /// Writes a TextFormat [String] representation of this message to [sink].
+  ///
+  /// Spec: https://protobuf.dev/reference/protobuf/textformat-spec/
+  void writeTextFormat(StringSink sink) {
+    _fieldSet.writeTextFormat(sink);
+  }
+}

protobuf/lib/src/protobuf/unknown_field_set.dart

@@ -180,6 +180,70 @@ class UnknownFieldSet {
     return stringBuffer.toString();
   }
 
+  void writeTextFormat(StringSink out, int indentLevel) {
+    for (final tag in sorted(_fields.keys)) {
+      final field = _fields[tag]!;
+      _writeUnknownFieldSetField(out, tag, field, indentLevel);
+    }
+  }
+
+  void _writeUnknownFieldSetField(
+    StringSink out,
+    int tag,
+    UnknownFieldSetField field,
+    int indentLevel,
+  ) {
+    void writeIndent(StringSink out, int indentLevel) {
+      for (var i = 0; i < indentLevel; i++) {
+        out.writeCharCode(32);
+        out.writeCharCode(32);
+      }
+    }
+
+    for (final value in field.varints) {
+      writeIndent(out, indentLevel);
+      out.write('$tag: ');
+      final bi = value.toInt64();
+      out.write(bi.toStringUnsigned());
+      out.write('\n');
+    }
+    for (final value in field.fixed32s) {
+      writeIndent(out, indentLevel);
+      out.write(
+        '$tag: 0x${value.toUnsigned(32).toRadixString(16).padLeft(8, '0')}\n',
+      );
+    }
+    for (final value in field.fixed64s) {
+      writeIndent(out, indentLevel);
+      out.write('$tag: ');
+      out.write('0x${value.toRadixStringUnsigned(16).padLeft(16, '0')}\n');
+    }
+    for (final value in field.lengthDelimited) {
+      writeIndent(out, indentLevel);
+      out.write('$tag: ');
+      try {
+        final ufs =
+            UnknownFieldSet()
+              ..mergeFromCodedBufferReader(CodedBufferReader(value));
+        out.write('{\n');
+        ufs.writeTextFormat(out, indentLevel + 1);
+        writeIndent(out, indentLevel);
+        out.write('}\n');
+      } on InvalidProtocolBufferException {
+        out.write('"');
+        escapeBytes(value, out);
+        out.write('"\n');
+      }
+    }
+    for (final value in field.groups) {
+      writeIndent(out, indentLevel);
+      out.write('$tag {\n');
+      value.writeTextFormat(out, indentLevel + 1);
+      writeIndent(out, indentLevel);
+      out.write('}\n');
+    }
+  }
+
   void writeToCodedBufferWriter(CodedBufferWriter output) {
     for (final entry in _fields.entries) {
       entry.value.writeTo(entry.key, output);

protobuf/lib/src/protobuf/utils.dart

@@ -32,6 +32,57 @@ bool areMapsEqual(Map<Object?, Object?> lhs, Map<Object?, Object?> rhs) {
 
 List<T> sorted<T>(Iterable<T> list) => List.from(list)..sort();
 
+/// Escapes slash, double quotes, and newlines in [s] with \ as needed
+/// for a TextFormat string.
+///
+/// This is a copy of the official Java implementation: https://github.com/protocolbuffers/protobuf/blob/main/java/core/src/main/java/com/google/protobuf/TextFormat.java#L632
+String escapeString(String s) {
+  return s
+      .replaceAll('\\', '\\\\')
+      .replaceAll('"', '\\"')
+      .replaceAll('\n', '\\n');
+}
+
+/// Appends the characters of [bytes] to [out] while escaping them as needed
+/// for a TextFormat string.
+///
+/// See TextFormat spec in https://protobuf.dev/reference/protobuf/textformat-spec/
+/// This is a copy of the official Java implementation: https://github.com/protocolbuffers/protobuf/blob/main/java/core/src/main/java/com/google/protobuf/TextFormatEscaper.java#L40
+void escapeBytes(List<int> bytes, StringSink out) {
+  for (final byte in bytes) {
+    // Only ASCII characters between 0x20 (space) and 0x7e (tilde) are
+    // printable.  Other byte values must be escaped.
+    switch (byte) {
+      case 0x07:
+        out.write(r'\a');
+      case 0x08:
+        out.write(r'\b');
+      case 0x0c:
+        out.write(r'\f');
+      case 0x0a:
+        out.write(r'\n');
+      case 0x0d:
+        out.write(r'\r');
+      case 0x09:
+        out.write(r'\t');
+      case 0x0b:
+        out.write(r'\v');
+      default:
+        if (byte >= 0x20 && byte < 0x7f) {
+          if (byte == 0x22 /* " */ || byte == 0x5c /* \ */ ) {
+            out.write(r'\');
+          }
+          out.writeCharCode(byte);
+        } else {
+          out.write(r'\');
+          out.write(((byte >> 6) & 3).toString());
+          out.write(((byte >> 3) & 7).toString());
+          out.write((byte & 7).toString());
+        }
+    }
+  }
+}
+
 class HashUtils {
   // Jenkins hash functions copied from
   // https://github.com/google/quiver-dart/blob/master/lib/src/core/hash.dart.

protobuf/pubspec.yaml

@@ -1,5 +1,5 @@
 name: protobuf
-version: 5.1.0
+version: 5.2.0
 description: >-
   Runtime library for protocol buffers support. Use with package:protoc_plugin
   to generate Dart code for your '.proto' files.

protobuf/test/json_test.dart

@@ -11,7 +11,7 @@ import 'dart:convert';
 import 'package:fixnum/fixnum.dart' show Int64;
 import 'package:test/test.dart';
 
-import 'mock_util.dart' show T, mockEnumValues;
+import 'mock_util.dart' show MockEnum, T;
 
 void main() {
   test('mergeFromProto3Json unknown enum fields with names', () {
@@ -21,7 +21,7 @@ void main() {
     expect(example.hasEnm, isFalse);
 
     // Defaults to first when it doesn't exist.
-    expect(example.enm, equals(mockEnumValues.first));
+    expect(example.enm, equals(MockEnum.values.first));
     expect((example..mergeFromProto3Json({'enm': 'a'})).enm.name, equals('a'));
 
     // Now it's explicitly set after merging.

protobuf/test/map_mixin_test.dart

@@ -32,21 +32,34 @@ void main() {
 
     expect(r.isEmpty, false);
     expect(r.isNotEmpty, true);
-    expect(r.keys, ['val', 'str', 'child', 'int32s', 'int64', 'enm']);
+    expect(r.keys, [
+      'val',
+      'str',
+      'child',
+      'int32s',
+      'int64',
+      'enm',
+      'stringMap',
+      'bytes',
+    ]);
 
     expect(r['val'], 42);
     expect(r['str'], '');
     expect(r['child'], isA<Rec>());
     expect(r['child'].toString(), 'Rec(42, "")');
     expect(r['int32s'], []);
+    expect(r['stringMap'], {});
+    expect(r['bytes'], []);
 
     final v = r.values;
-    expect(v.length, 6);
+    expect(v.length, 8);
     expect(v.first, 42);
     expect(v.toList()[1], '');
     expect(v.toList()[3].toString(), '[]');
     expect(v.toList()[4], 0);
     expect((v.toList()[5] as ProtobufEnum).name, 'a');
+    expect(v.toList()[6], {});
+    expect(v.toList()[7], []);
   });
 
   test('operator []= sets record fields', () {