dev/benchmarks/microbenchmarks/lib/language/sync_star_semantics_bench.dart

// Copyright 2014 The Flutter Authors. 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:flutter/widgets.dart';

import '../common.dart';

const int _kNumIterations = 1000;
const int _kNumWarmUp = 100;

void main() {
  final List<String> words = 'Lorem Ipsum is simply dummy text of the printing and'
    " typesetting industry. Lorem Ipsum has been the industry's"
    ' standard dummy text ever since the 1500s, when an unknown'
    ' printer took a galley of type and scrambled it to make a'
    ' type specimen book'.split(' ');
  final List<InlineSpanSemanticsInformation> data = <InlineSpanSemanticsInformation>[];
  for (int i = 0; i < words.length; i++) {
    if (i.isEven) {
      data.add(
        InlineSpanSemanticsInformation(words[i], isPlaceholder: false),
      );
    } else if (i % 2 == 0) {
      data.add(
        InlineSpanSemanticsInformation(words[i], isPlaceholder: true),
      );
    }
  }
  print(words);

  // Warm up lap
  for (int i = 0; i < _kNumWarmUp; i += 1) {
    combineSemanticsInfoSyncStar(data);
    combineSemanticsInfoList(data);
  }

  final Stopwatch watch = Stopwatch();
  watch.start();
  for (int i = 0; i < _kNumIterations; i += 1) {
    consumeSpan(combineSemanticsInfoSyncStar(data));
  }
  final int combineSemanticsInfoSyncStarTime = watch.elapsedMicroseconds;
  watch
    ..reset()
    ..start();
  for (int i = 0; i < _kNumIterations; i += 1) {
    consumeSpan(combineSemanticsInfoList(data));
  }
  final int combineSemanticsInfoListTime = watch.elapsedMicroseconds;
  watch
    ..reset()
    ..start();

  final BenchmarkResultPrinter printer = BenchmarkResultPrinter();
  const double scale = 1000.0 / _kNumIterations;
  printer.addResult(
    description: 'combineSemanticsInfoSyncStar',
    value: combineSemanticsInfoSyncStarTime * scale,
    unit: 'ns per iteration',
    name: 'combineSemanticsInfoSyncStar_iteration',
  );
  printer.addResult(
    description: 'combineSemanticsInfoList',
    value: combineSemanticsInfoListTime * scale,
    unit: 'ns per iteration',
    name: 'combineSemanticsInfoList_iteration',
  );
  printer.printToStdout();
}

String consumeSpan(Iterable<InlineSpanSemanticsInformation> items) {
  String result = '';
  for (final InlineSpanSemanticsInformation span in items) {
    result += span.text;
  }
  return result;
}


Iterable<InlineSpanSemanticsInformation> combineSemanticsInfoSyncStar(List<InlineSpanSemanticsInformation> inputs) sync* {
  String workingText = '';
  String workingLabel;
  for (final InlineSpanSemanticsInformation info in inputs) {
    if (info.requiresOwnNode) {
      if (workingText != null) {
        yield InlineSpanSemanticsInformation(workingText, semanticsLabel: workingLabel ?? workingText);
        workingText = '';
        workingLabel = null;
      }
      yield info;
    } else {
      workingText += info.text;
      workingLabel ??= '';
      if (info.semanticsLabel != null) {
        workingLabel += info.semanticsLabel;
      } else {
        workingLabel += info.text;
      }
    }
  }
  if (workingText != null) {
    yield InlineSpanSemanticsInformation(workingText, semanticsLabel: workingLabel);
  } else {
    assert(workingLabel != null);
  }
}

Iterable<InlineSpanSemanticsInformation> combineSemanticsInfoList(List<InlineSpanSemanticsInformation> inputs) {
  String workingText = '';
  String workingLabel;
  final List<InlineSpanSemanticsInformation> result = <InlineSpanSemanticsInformation>[];
  for (final InlineSpanSemanticsInformation info in inputs) {
    if (info.requiresOwnNode) {
      if (workingText != null) {
        result.add(InlineSpanSemanticsInformation(workingText, semanticsLabel: workingLabel ?? workingText));
        workingText = '';
        workingLabel = null;
      }
      result.add(info);
    } else {
      workingText += info.text;
      workingLabel ??= '';
      if (info.semanticsLabel != null) {
        workingLabel += info.semanticsLabel;
      } else {
        workingLabel += info.text;
      }
    }
  }
  if (workingText != null) {
    result.add(InlineSpanSemanticsInformation(workingText, semanticsLabel: workingLabel));
  } else {
    assert(workingLabel != null);
  }
  return result;
}