Merge pull request #498 from dart-lang:remove_intl_stream

PiperOrigin-RevId: 495066469

Author: copybara-github

benchmark/string_char_conversion_benchmark.dart

@@ -0,0 +1,63 @@
+// Copyright (c) 2022, 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 'dart:math';
+
+import 'package:benchmark_harness/benchmark_harness.dart';
+
+const int asciiZeroCodeUnit = 2;
+const int listlength = 10000;
+
+String string = String.fromCharCodes(Iterable.generate(
+  listlength,
+  (_) => Random().nextInt(80) + 15,
+));
+
+/// This class tests the implementation speed of
+/// _DateFormatPatternField::nextInteger, which is assumed to be called often and
+/// thus being performance-critical.
+class NewMethod extends BenchmarkBase {
+  late String result;
+  int zeroDigit = 15;
+  NewMethod() : super('New version of _DateFormatPatternField::nextInteger');
+
+  @override
+  void run() {
+    var codeUnits = string.codeUnits;
+    result = String.fromCharCodes(List.generate(
+      codeUnits.length,
+      (index) => codeUnits[index] - zeroDigit + asciiZeroCodeUnit,
+      growable: false,
+    ));
+  }
+}
+
+// THIS WILL BE REMOVED AFTER CR
+class OldMethod extends BenchmarkBase {
+  late String result;
+  int zeroDigit = 15;
+  OldMethod() : super('Old version of _DateFormatPatternField::nextInteger');
+
+  @override
+  void setup() => string = String.fromCharCodes(Iterable.generate(
+        listlength,
+        (index) => Random().nextInt(80) + zeroDigit,
+      ));
+
+  @override
+  void run() {
+    var oldDigits = string.codeUnits;
+    var newDigits = List<int>.filled(string.length, 0);
+    for (var i = 0; i < string.length; i++) {
+      newDigits[i] = oldDigits[i] - zeroDigit + asciiZeroCodeUnit;
+    }
+    result = String.fromCharCodes(newDigits);
+  }
+}
+// THIS WILL BE REMOVED AFTER CR
+
+void main() {
+  OldMethod().report();
+  NewMethod().report();
+}

lib/src/intl/date_format.dart

@@ -10,8 +10,8 @@ import 'package:meta/meta.dart';
 import 'constants.dart' as constants;
 import 'date_builder.dart';
 import 'date_computation.dart' as date_computation;
-import 'intl_stream.dart';
 import 'regexp.dart' as regexp;
+import 'string_stack.dart';
 
 part 'date_format_field.dart';
 
@@ -350,11 +350,11 @@ class DateFormat {
   DateTime _parseLoose(String inputString, bool utc) {
     var dateFields = DateBuilder(locale, dateTimeConstructor);
     if (utc) dateFields.utc = true;
-    var stream = IntlStream(inputString);
+    var stack = StringStack(inputString);
     for (var field in _formatFields) {
-      field.parseLoose(stream, dateFields);
+      field.parseLoose(stack, dateFields);
     }
-    if (!stream.atEnd()) {
+    if (!stack.atEnd) {
       throw FormatException(
           'Characters remaining after date parsing in $inputString');
     }
@@ -379,11 +379,11 @@ class DateFormat {
     var dateFields = DateBuilder(locale, dateTimeConstructor);
     if (utc) dateFields.utc = true;
     dateFields.dateOnly = dateOnly;
-    var stream = IntlStream(inputString);
+    var stack = StringStack(inputString);
     for (var field in _formatFields) {
-      field.parse(stream, dateFields);
+      field.parse(stack, dateFields);
     }
-    if (strict && !stream.atEnd()) {
+    if (strict && !stack.atEnd) {
       throw FormatException(
           'Characters remaining after date parsing in $inputString');
     }