Tweak uses of RegExp and parsing using them.

protobuf/lib/src/protobuf/mixins/well_known.dart

@@ -168,7 +168,7 @@ String _typeNameFromUrl(String typeUrl) {
 }
 
 mixin TimestampMixin {
-  static final RegExp finalGroupsOfThreeZeroes = RegExp(r'(?:000)*$');
+  static final RegExp finalGroupsOfThreeZeroes = RegExp(r'(?:000)+$');
 
   Int64 get seconds;
   set seconds(Int64 value);
@@ -192,9 +192,15 @@ mixin TimestampMixin {
   ///
   /// Time zone information will not be preserved.
   static void setFromDateTime(TimestampMixin target, DateTime dateTime) {
-    final micros = dateTime.microsecondsSinceEpoch;
-    target.seconds = Int64((micros / Duration.microsecondsPerSecond).floor());
-    target.nanos = (micros % Duration.microsecondsPerSecond).toInt() * 1000;
+    var micros = dateTime.microsecondsSinceEpoch;
+    var seconds = micros ~/ Duration.microsecondsPerSecond;
+    micros = micros.remainder(Duration.microsecondsPerSecond);
+    if (micros < 0) {
+      seconds -= 1;
+      micros += Duration.microsecondsPerSecond;
+    }
+    target.seconds = Int64(seconds);
+    target.nanos = micros * 1000;
   }
 
   static String _twoDigits(int n) {
@@ -268,10 +274,10 @@ mixin TimestampMixin {
     JsonParsingContext context,
   ) {
     if (json is String) {
-      var jsonWithoutFracSec = json;
       var nanos = 0;
-      final Match? fracSecsMatch = RegExp(r'\.(\d+)').firstMatch(json);
-      if (fracSecsMatch != null) {
+      var jsonWithoutFracSec = json.replaceFirstMapped(RegExp(r'\.(\d+)'), (
+        fracSecsMatch,
+      ) {
         final fracSecs = fracSecsMatch[1]!;
         if (fracSecs.length > 9) {
           throw context.parseException(
@@ -280,12 +286,8 @@ mixin TimestampMixin {
           );
         }
         nanos = int.parse(fracSecs.padRight(9, '0'));
-        jsonWithoutFracSec = json.replaceRange(
-          fracSecsMatch.start,
-          fracSecsMatch.end,
-          '',
-        );
-      }
+        return '';
+      });
       final dateTimeWithoutFractionalSeconds =
           DateTime.tryParse(jsonWithoutFracSec) ??
           (throw context.parseException(
@@ -319,16 +321,30 @@ mixin DurationMixin {
     TypeRegistry typeRegistry,
   ) {
     final duration = message as DurationMixin;
-    final secFrac = duration.nanos
-        // nanos and seconds should always have the same sign.
+    final seconds = duration.seconds;
+    final nanos = duration.nanos;
+    // Extra sign needed if `seconds` is zero and nanos is negative.
+    final sign = seconds.isZero && nanos < 0 ? '-' : '';
+
+    return '$sign$seconds${_toNanosString(nanos)}s';
+  }
+
+  /// Nanoseconds as fractional seconds.
+  ///
+  /// Is empty if [nanos] is zero, otherwise the digits of
+  /// (absolute value) of `nanos` as billionths of seconds
+  /// with no trailing zeros.
+  static String _toNanosString(int nanos) {
+    if (nanos == 0) return '';
+    final digits = nanos
         .abs()
         .toString()
         .padLeft(9, '0')
         .replaceFirst(finalZeroes, '');
-    final secPart = secFrac == '' ? '' : '.$secFrac';
-    return '${duration.seconds}${secPart}s';
+    return '.$digits';
   }
 
+  // Matches `-?\d*\.?\d*s$`, grouping is only to control captures.
   static final RegExp durationPattern = RegExp(r'(-?\d*)(?:\.(\d*))?s$');
 
   static void fromProto3JsonHelper(
@@ -340,25 +356,33 @@ mixin DurationMixin {
     final duration = message as DurationMixin;
     if (json is String) {
       final match = durationPattern.matchAsPrefix(json);
-      if (match == null) {
-        throw context.parseException(
-          'Expected a String of the form `<seconds>.<nanos>s`',
-          json,
-        );
-      } else {
+      if (match != null) {
         final secondsString = match[1]!;
-        final seconds =
-            secondsString == '' ? Int64.ZERO : Int64.parseInt(secondsString);
-        duration.seconds = seconds;
-        final nanos = int.parse((match[2] ?? '').padRight(9, '0'));
-        duration.nanos = seconds < 0 ? -nanos : nanos;
+        final isNegative = secondsString.startsWith('-');
+        duration.seconds =
+            (secondsString.length == (isNegative ? 1 : 0))
+                ? Int64.ZERO
+                : Int64.parseInt(secondsString);
+        var fractionalSeconds = match[2];
+        var nanos = 0;
+        if (fractionalSeconds != null) {
+          if (fractionalSeconds.length > 9) {
+            // Shouldn't happen for valid input.
+            fractionalSeconds = fractionalSeconds.substring(0, 9);
+          } else {
+            fractionalSeconds = fractionalSeconds.padRight(9, '0');
+          }
+          nanos = int.parse(fractionalSeconds);
+          if (isNegative) nanos = -nanos;
+        }
+        duration.nanos = nanos;
+        return;
       }
-    } else {
-      throw context.parseException(
-        'Expected a String of the form `<seconds>.<nanos>s`',
-        json,
-      );
     }
+    throw context.parseException(
+      'Expected a String of the form `<seconds>.<nanos>s`',
+      json,
+    );
   }
 }
 
@@ -565,7 +589,7 @@ mixin FieldMaskMixin {
   ) {
     final fieldMask = message as FieldMaskMixin;
     for (final path in fieldMask.paths) {
-      if (path.contains(RegExp('[A-Z]|_[^a-z]'))) {
+      if (path.contains(RegExp(r'[A-Z]|_[^a-z]'))) {
         throw ArgumentError(
           'Bad fieldmask $path. Does not round-trip to json.',
         );
@@ -587,7 +611,7 @@ mixin FieldMaskMixin {
           json,
         );
       }
-      if (json == '') {
+      if (json.isEmpty) {
         // The empty string splits to a single value. So this is a special case.
         return;
       }
@@ -604,15 +628,15 @@ mixin FieldMaskMixin {
 
   static String _toCamelCase(String name) {
     return name.replaceAllMapped(
-      RegExp('_([a-z])'),
-      (Match m) => m.group(1)!.toUpperCase(),
+      RegExp(r'_[a-z]'),
+      (Match m) => name[m.start + 1].toUpperCase(),
     );
   }
 
   static String _fromCamelCase(String name) {
     return name.replaceAllMapped(
-      RegExp('[A-Z]'),
-      (Match m) => '_${m.group(0)!.toLowerCase()}',
+      RegExp(r'[A-Z]'),
+      (Match m) => '_${m[0]!.toLowerCase()}',
     );
   }
 }

protobuf/lib/well_known_types/google/protobuf/duration.pb.dart

@@ -167,7 +167,9 @@ class Duration extends $pb.GeneratedMessage with $mixin.DurationMixin {
   static Duration fromDart($core.Duration duration) => Duration()
     ..seconds = $fixnum.Int64(duration.inSeconds)
     ..nanos =
-        (duration.inMicroseconds % $core.Duration.microsecondsPerSecond) * 1000;
+        duration.inMicroseconds
+            .remainder($core.Duration.microsecondsPerSecond) *
+        1000;
 }
 
 const $core.bool _omitFieldNames =

protoc_plugin/lib/names.dart

@@ -145,7 +145,7 @@ Iterable<String> extensionSuffixes() sync* {
 ///
 /// This function does not take care of leading underscores.
 String legalDartIdentifier(String input) {
-  return input.replaceAll(RegExp(r'[^a-zA-Z0-9$_]'), '_');
+  return input.replaceAll(RegExp(r'[^\w$]'), '_');
 }
 
 /// Chooses the name of the Dart class holding top-level extensions.
@@ -592,7 +592,7 @@ String? _nameOption(FieldDescriptorProto field) =>
 
 bool _isDartFieldName(String name) => name.startsWith(_dartFieldNameExpr);
 
-final _dartFieldNameExpr = RegExp(r'^[a-z]\w+$');
+final _dartFieldNameExpr = RegExp(r'^[a-z]\w*$');
 
 /// Names that would collide as top-level identifiers.
 final List<String> forbiddenTopLevelNames = <String>[

protoc_plugin/lib/src/file_generator.dart

@@ -4,7 +4,7 @@
 
 part of '../protoc.dart';
 
-final RegExp _dartIdentifier = RegExp(r'^\w+$');
+final RegExp _dartIdentifier = RegExp(r'^[a-zA-Z_]\w*$');
 
 const String _asyncImportUrl = 'dart:async';
 

protoc_plugin/lib/src/protobuf_field.dart

@@ -6,20 +6,10 @@ part of '../protoc.dart';
 
 class ProtobufField {
   static final RegExp _hexLiteralRegex = RegExp(
-    r'^0x[0-9a-f]+$',
-    multiLine: false,
-    caseSensitive: false,
+    r'^0x[\da-fA-F]+$',
   );
-  static final RegExp _integerLiteralRegex = RegExp(r'^[+-]?[0-9]+$');
-  static final RegExp _decimalLiteralRegexA = RegExp(
-    r'^[+-]?([0-9]*)\.[0-9]+(e[+-]?[0-9]+)?$',
-    multiLine: false,
-    caseSensitive: false,
-  );
-  static final RegExp _decimalLiteralRegexB = RegExp(
-    r'^[+-]?[0-9]+e[+-]?[0-9]+$',
-    multiLine: false,
-    caseSensitive: false,
+  static final RegExp _decimalLiteralRegex = RegExp(
+    r'^[+\-]?(\d*\.)?\d+([eE][+\-]?\d+)?$',
   );
 
   final FieldDescriptorProto descriptor;
@@ -411,10 +401,12 @@ class ProtobufField {
           return '$coreImportPrefix.double.nan';
         } else if (_hexLiteralRegex.hasMatch(descriptor.defaultValue)) {
           return '(${descriptor.defaultValue}).toDouble()';
-        } else if (_integerLiteralRegex.hasMatch(descriptor.defaultValue)) {
-          return '${descriptor.defaultValue}.0';
-        } else if (_decimalLiteralRegexA.hasMatch(descriptor.defaultValue) ||
-            _decimalLiteralRegexB.hasMatch(descriptor.defaultValue)) {
+        } else if (_decimalLiteralRegex.matchAsPrefix(descriptor.defaultValue)
+            case final match?) {
+          if (match[1] == null && match[2] == null) {
+            // Integer literal, no `.` or `e` parts.
+            return '${descriptor.defaultValue}.0';
+          }
           return descriptor.defaultValue;
         }
         throw _invalidDefaultValue;
@@ -502,7 +494,7 @@ class ProtobufField {
   static String _unCamelCase(String name) {
     return name.replaceAllMapped(
       _upperCase,
-      (match) => '_${match.group(0)!.toLowerCase()}',
+      (match) => '_${match[0]!.toLowerCase()}',
     );
   }
 }

protoc_plugin/lib/src/shared.dart

@@ -71,25 +71,25 @@ String? toDartComment(String value) {
 
   if (value.isEmpty) return null;
 
-  var lines = LineSplitter.split(value).toList();
+  var lines = LineSplitter.split(value)
+      .map((line) => line.trimRight())
+      .toList();
 
   // Find any leading spaces in the first line. If all of the lines have the
   // same leading spaces, remove them all.
   final leadingSpaces = _leadingSpaces.firstMatch(lines.first);
   if (leadingSpaces != null) {
-    final prefix = leadingSpaces.group(0)!;
+    final prefix = leadingSpaces[0]!;
     if (lines.every((line) => line.isEmpty || line.startsWith(prefix))) {
-      lines =
-          lines
-              .map(
-                (line) => line.isEmpty ? line : line.substring(prefix.length),
-              )
-              .toList();
+      for (var i = 0; i < lines.length; i++) {
+        var line = lines[i];
+        if (line.isNotEmpty) lines[i] = line.substring(prefix.length);
+      }
     }
   }
 
   // Remove empty, trailing lines.
-  while (lines.isNotEmpty && lines.last.trim().isEmpty) {
+  while (lines.isNotEmpty && lines.last.isEmpty) {
     lines.removeLast();
   }
 
@@ -98,7 +98,7 @@ String? toDartComment(String value) {
     return null;
   }
 
-  return lines.map((e) => '/// $e'.trimRight()).join('\n');
+  return lines.map((e) => e.isEmpty ? '///' : '/// $e').join('\n');
 }
 
 final _leadingSpaces = RegExp('^ +');

protoc_plugin/lib/src/well_known_types.dart

@@ -64,7 +64,10 @@ $coreImportPrefix.Duration toDart() =>
 /// Creates a new instance from [$coreImportPrefix.Duration].
 static Duration fromDart($coreImportPrefix.Duration duration) => Duration()
   ..seconds = $fixnumImportPrefix.Int64(duration.inSeconds)
-  ..nanos = (duration.inMicroseconds % $coreImportPrefix.Duration.microsecondsPerSecond) * 1000;
+  ..nanos =
+      duration.inMicroseconds
+          .remainder($coreImportPrefix.Duration.microsecondsPerSecond) *
+      1000;
 ''',
     ],
     wellKnownType: 'duration',

protoc_plugin/test/duration_test.dart

@@ -35,6 +35,9 @@ void main() {
     );
 
     expect(pb.Duration.fromDart(coreDuration).toDart(), coreDuration);
+
+    final coreDuration2 = Duration(milliseconds: -500);
+    expect(pb.Duration.fromDart(coreDuration2).toDart(), coreDuration2);
   });
 
   test('proto duration -> core duration -> proto duration', () {

protoc_plugin/test/proto3_json_test.dart

@@ -450,7 +450,7 @@ void main() {
       predicate((e) {
         if (e is FormatException) {
           final pathExpression =
-              RegExp(r'root(\["[^"]*"]*\])*').firstMatch(e.message)![0]!;
+              RegExp(r'root(?:\["[^"]*"\])*').firstMatch(e.message)![0]!;
           final actualPath =
               RegExp(
                 r'\["([^"]*)"\]',
@@ -1230,6 +1230,12 @@ void main() {
           ..seconds = Int64(10)
           ..nanos = 10,
       );
+      expect(
+        Duration()..mergeFromProto3Json('10.000000001999s'),
+        Duration()
+          ..seconds = Int64(10)
+          ..nanos = 1,
+      );
       expect(
         Duration()..mergeFromProto3Json('-1.000099s'),
         Duration()
@@ -1255,6 +1261,18 @@ void main() {
           ..seconds = Int64(0)
           ..nanos = 500000000,
       );
+      expect(
+        Duration()..mergeFromProto3Json('-.5s'),
+        Duration()
+          ..seconds = Int64(0)
+          ..nanos = -500000000,
+      );
+      expect(
+        Duration()..mergeFromProto3Json('-0.0s'),
+        Duration()
+          ..seconds = Int64(0)
+          ..nanos = 0,
+      );
       expect(
         Duration()..mergeFromProto3Json('5.s'),
         Duration()
@@ -1267,6 +1285,18 @@ void main() {
           ..seconds = Int64(0)
           ..nanos = 0,
       );
+      expect(
+        Duration()..mergeFromProto3Json('-s'),
+        Duration()
+          ..seconds = Int64(0)
+          ..nanos = 0,
+      );
+      expect(
+        Duration()..mergeFromProto3Json('s'),
+        Duration()
+          ..seconds = Int64(0)
+          ..nanos = 0,
+      );
       expect(() => Duration()..mergeFromProto3Json('0.5'), parseFailure([]));
       expect(() => Duration()..mergeFromProto3Json(100), parseFailure([]));
     });