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// Copyright 2014 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

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// See ../snippets/README.md for documentation.

// To run this, from the root of the Flutter repository:
//   bin/cache/dart-sdk/bin/dart dev/bots/analyze-sample-code.dart
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import 'dart:io';

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import 'package:args/args.dart';
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import 'package:path/path.dart' as path;

final String _flutterRoot = path.dirname(path.dirname(path.dirname(path.fromUri(Platform.script))));
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final String _defaultFlutterPackage = path.join(_flutterRoot, 'packages', 'flutter', 'lib');
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final String _flutter = path.join(_flutterRoot, 'bin', Platform.isWindows ? 'flutter.bat' : 'flutter');

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void main(List<String> arguments) {
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  final ArgParser argParser = ArgParser();
  argParser.addOption(
    'temp',
    defaultsTo: null,
    help: 'A location where temporary files may be written. Defaults to a '
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          'directory in the system temp folder. If specified, will not be '
          'automatically removed at the end of execution.',
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  );
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  argParser.addFlag(
    'verbose',
    defaultsTo: false,
    negatable: false,
    help: 'Print verbose output for the analysis process.',
  );
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  argParser.addFlag(
    'help',
    defaultsTo: false,
    negatable: false,
    help: 'Print help for this command.',
  );

  final ArgResults parsedArguments = argParser.parse(arguments);

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  if (parsedArguments['help'] as bool) {
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    print(argParser.usage);
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    print('See dev/snippets/README.md for documentation.');
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    exit(0);
  }

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  Directory flutterPackage;
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  if (parsedArguments.rest.length == 1) {
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    // Used for testing.
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    flutterPackage = Directory(parsedArguments.rest.single);
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  } else {
    flutterPackage = Directory(_defaultFlutterPackage);
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  }
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  Directory tempDirectory;
  if (parsedArguments.wasParsed('temp')) {
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    final String tempArg = parsedArguments['temp'] as String;
    tempDirectory = Directory(path.join(Directory.systemTemp.absolute.path, path.basename(tempArg)));
    if (path.basename(tempArg) != tempArg) {
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      stderr.writeln('Supplied temporary directory name should be a name, not a path. Using ${tempDirectory.absolute.path} instead.');
    }
    print('Leaving temporary output in ${tempDirectory.absolute.path}.');
    // Make sure that any directory left around from a previous run is cleared
    // out.
    if (tempDirectory.existsSync()) {
      tempDirectory.deleteSync(recursive: true);
    }
    tempDirectory.createSync();
  }
  try {
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    exitCode = SampleChecker(
      flutterPackage,
      tempDirectory: tempDirectory,
      verbose: parsedArguments['verbose'] as bool,
    ).checkSamples();
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  } on SampleCheckerException catch (e) {
    stderr.write(e);
    exit(1);
  }
}

class SampleCheckerException implements Exception {
  SampleCheckerException(this.message, {this.file, this.line});
  final String message;
  final String file;
  final int line;

  @override
  String toString() {
    if (file != null || line != null) {
      final String fileStr = file == null ? '' : '$file:';
      final String lineStr = line == null ? '' : '$line:';
      return '$fileStr$lineStr Error: $message';
    } else {
      return 'Error: $message';
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    }
  }
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}

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/// Checks samples and code snippets for analysis errors.
///
/// Extracts dartdoc content from flutter package source code, identifies code
/// sections, and writes them to a temporary directory, where 'flutter analyze'
/// is used to analyze the sources for problems. If problems are found, the
/// error output from the analyzer is parsed for details, and the problem
/// locations are translated back to the source location.
///
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/// For samples, the samples are generated using the snippets tool, and they
/// are analyzed with the snippets. If errors are found in samples, then the
/// line number of the start of the sample is given instead of the actual error
/// line, since samples get reformatted when written, and the line numbers
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/// don't necessarily match. It does, however, print the source of the
/// problematic line.
class SampleChecker {
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  SampleChecker(this._flutterPackage, {Directory tempDirectory, this.verbose = false})
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      : _tempDirectory = tempDirectory,
        _keepTmp = tempDirectory != null {
    _tempDirectory ??= Directory.systemTemp.createTempSync('flutter_analyze_sample_code.');
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  }

  /// The prefix of each comment line
  static const String _dartDocPrefix = '///';

  /// The prefix of each comment line with a space appended.
  static const String _dartDocPrefixWithSpace = '$_dartDocPrefix ';

  /// A RegExp that matches the beginning of a dartdoc snippet or sample.
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  static final RegExp _dartDocSampleBeginRegex = RegExp(r'{@tool (sample|snippet|dartpad)(?:| ([^}]*))}');
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  /// A RegExp that matches the end of a dartdoc snippet or sample.
  static final RegExp _dartDocSampleEndRegex = RegExp(r'{@end-tool}');

  /// A RegExp that matches the start of a code block within dartdoc.
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  static final RegExp _codeBlockStartRegex = RegExp(r'///\s+```dart.*$');
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  /// A RegExp that matches the end of a code block within dartdoc.
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  static final RegExp _codeBlockEndRegex = RegExp(r'///\s+```\s*$');
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  /// A RegExp that matches a Dart constructor.
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  static final RegExp _constructorRegExp = RegExp(r'(const\s+)?_*[A-Z][a-zA-Z0-9<>._]*\(');
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  /// Whether or not to print verbose output.
  final bool verbose;

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  /// Whether or not to keep the temp directory around after running.
  ///
  /// Defaults to false.
  final bool _keepTmp;

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  /// The temporary directory where all output is written. This will be deleted
  /// automatically if there are no errors.
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  Directory _tempDirectory;
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  /// The package directory for the flutter package within the flutter root dir.
  final Directory _flutterPackage;

  /// A serial number so that we can create unique expression names when we
  /// generate them.
  int _expressionId = 0;

  /// The exit code from the analysis process.
  int _exitCode = 0;

  // Once the snippets tool has been precompiled by Dart, this contains the AOT
  // snapshot.
  String _snippetsSnapshotPath;

  /// Finds the location of the snippets script.
  String get _snippetsExecutable {
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    final String platformScriptPath = path.dirname(path.fromUri(Platform.script));
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    return path.canonicalize(path.join(platformScriptPath, '..', 'snippets', 'lib', 'main.dart'));
  }

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  /// Finds the location of the Dart executable.
  String get _dartExecutable {
    final File dartExecutable = File(Platform.resolvedExecutable);
    return dartExecutable.absolute.path;
  }

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  static List<File> _listDartFiles(Directory directory, {bool recursive = false}) {
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    return directory.listSync(recursive: recursive, followLinks: false).whereType<File>().where((File file) => path.extension(file.path) == '.dart').toList();
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  }

  /// Computes the headers needed for each sample file.
  List<Line> get headers {
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    return _headers ??= <String>[
      '// generated code',
      "import 'dart:async';",
      "import 'dart:convert';",
      "import 'dart:math' as math;",
      "import 'dart:typed_data';",
      "import 'dart:ui' as ui;",
      "import 'package:flutter_test/flutter_test.dart';",
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      for (final File file in _listDartFiles(Directory(_defaultFlutterPackage))) ...<String>[
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        '',
        '// ${file.path}',
        "import 'package:flutter/${path.basename(file.path)}';",
      ],
    ].map<Line>((String code) => Line(code)).toList();
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  }

  List<Line> _headers;

  /// Checks all the samples in the Dart files in [_flutterPackage] for errors.
  int checkSamples() {
    _exitCode = 0;
    Map<String, List<AnalysisError>> errors = <String, List<AnalysisError>>{};
    try {
      final Map<String, Section> sections = <String, Section>{};
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      final Map<String, Sample> snippets = <String, Sample>{};
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      _extractSamples(sections, snippets);
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      errors = _analyze(_tempDirectory, sections, snippets);
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    } finally {
      if (errors.isNotEmpty) {
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        for (final String filePath in errors.keys) {
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          errors[filePath].forEach(stderr.writeln);
        }
        stderr.writeln('\nFound ${errors.length} sample code errors.');
      }
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      if (_keepTmp) {
        print('Leaving temporary directory ${_tempDirectory.path} around for your perusal.');
      } else {
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        try {
          _tempDirectory.deleteSync(recursive: true);
        } on FileSystemException catch (e) {
          stderr.writeln('Failed to delete ${_tempDirectory.path}: $e');
        }
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      }
      // If we made a snapshot, remove it (so as not to clutter up the tree).
      if (_snippetsSnapshotPath != null) {
        final File snapshot = File(_snippetsSnapshotPath);
        if (snapshot.existsSync()) {
          snapshot.deleteSync();
        }
      }
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    }
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    return _exitCode;
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  }
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  /// Creates a name for the snippets tool to use for the snippet ID from a
  /// filename and starting line number.
  String _createNameFromSource(String prefix, String filename, int start) {
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    String sampleId = path.split(filename).join('.');
    sampleId = path.basenameWithoutExtension(sampleId);
    sampleId = '$prefix.$sampleId.$start';
    return sampleId;
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  }

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  // Precompiles the snippets tool if _snippetsSnapshotPath isn't set yet, and
  // runs the precompiled version if it is set.
  ProcessResult _runSnippetsScript(List<String> args) {
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    final String workingDirectory = path.join(_flutterRoot, 'dev', 'docs');
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    if (_snippetsSnapshotPath == null) {
      _snippetsSnapshotPath = '$_snippetsExecutable.snapshot';
      return Process.runSync(
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        _dartExecutable,
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        <String>[
          '--snapshot=$_snippetsSnapshotPath',
          '--snapshot-kind=app-jit',
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          path.canonicalize(_snippetsExecutable),
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          ...args,
        ],
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        workingDirectory: workingDirectory,
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      );
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    } else {
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      return Process.runSync(
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        _dartExecutable,
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        <String>[path.canonicalize(_snippetsSnapshotPath), ...args],
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        workingDirectory: workingDirectory,
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      );
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    }
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  }

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  /// Writes out the given sample to an output file in the [_tempDirectory] and
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  /// returns the output file.
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  File _writeSample(Sample sample) {
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    // Generate the snippet.
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    final String sampleId = _createNameFromSource('sample', sample.start.filename, sample.start.line);
    final String inputName = '$sampleId.input';
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    // Now we have a filename like 'lib.src.material.foo_widget.123.dart' for each snippet.
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    final File inputFile = File(path.join(_tempDirectory.path, inputName))..createSync(recursive: true);
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    inputFile.writeAsStringSync(sample.input.join('\n'));
    final File outputFile = File(path.join(_tempDirectory.path, '$sampleId.dart'));
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    final List<String> args = <String>[
      '--output=${outputFile.absolute.path}',
      '--input=${inputFile.absolute.path}',
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      ...sample.args,
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    ];
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    if (verbose)
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      print('Generating sample for ${sample.start?.filename}:${sample.start?.line}');
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    final ProcessResult process = _runSnippetsScript(args);
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    if (verbose)
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      stderr.write('${process.stderr}');
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    if (process.exitCode != 0) {
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      throw SampleCheckerException(
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        'Unable to create sample for ${sample.start.filename}:${sample.start.line} '
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            '(using input from ${inputFile.path}):\n${process.stdout}\n${process.stderr}',
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        file: sample.start.filename,
        line: sample.start.line,
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      );
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    }
    return outputFile;
  }

  /// Extracts the samples from the Dart files in [_flutterPackage], writes them
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  /// to disk, and adds them to the appropriate [sectionMap] or [sampleMap].
  void _extractSamples(Map<String, Section> sectionMap, Map<String, Sample> sampleMap) {
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    final List<Section> sections = <Section>[];
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    final List<Sample> samples = <Sample>[];
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    for (final File file in _listDartFiles(_flutterPackage, recursive: true)) {
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      final String relativeFilePath = path.relative(file.path, from: _flutterPackage.path);
      final List<String> sampleLines = file.readAsLinesSync();
      final List<Section> preambleSections = <Section>[];
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      // Whether or not we're in the file-wide preamble section ("Examples can assume").
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      bool inPreamble = false;
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      // Whether or not we're in a code sample
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      bool inSampleSection = false;
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      // Whether or not we're in a snippet code sample (with template) specifically.
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      bool inSnippet = false;
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      // Whether or not we're in a '```dart' segment.
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      bool inDart = false;
      int lineNumber = 0;
      final List<String> block = <String>[];
      List<String> snippetArgs = <String>[];
      Line startLine;
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      for (final String line in sampleLines) {
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        lineNumber += 1;
        final String trimmedLine = line.trim();
        if (inSnippet) {
          if (!trimmedLine.startsWith(_dartDocPrefix)) {
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            throw SampleCheckerException('Snippet section unterminated.', file: relativeFilePath, line: lineNumber);
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          }
          if (_dartDocSampleEndRegex.hasMatch(trimmedLine)) {
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            samples.add(
              Sample(
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                start: startLine,
                input: block,
                args: snippetArgs,
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                serial: samples.length,
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              ),
            );
            snippetArgs = <String>[];
            block.clear();
            inSnippet = false;
            inSampleSection = false;
          } else {
            block.add(line.replaceFirst(RegExp(r'\s*/// ?'), ''));
          }
        } else if (inPreamble) {
          if (line.isEmpty) {
            inPreamble = false;
            preambleSections.add(_processBlock(startLine, block));
            block.clear();
          } else if (!line.startsWith('// ')) {
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            throw SampleCheckerException('Unexpected content in sample code preamble.', file: relativeFilePath, line: lineNumber);
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          } else {
            block.add(line.substring(3));
          }
        } else if (inSampleSection) {
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          if (_dartDocSampleEndRegex.hasMatch(trimmedLine)) {
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            if (inDart) {
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              throw SampleCheckerException("Dart section didn't terminate before end of sample", file: relativeFilePath, line: lineNumber);
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            }
            inSampleSection = false;
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          }
          if (inDart) {
            if (_codeBlockEndRegex.hasMatch(trimmedLine)) {
              inDart = false;
              final Section processed = _processBlock(startLine, block);
              if (preambleSections.isEmpty) {
                sections.add(processed);
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              } else {
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                sections.add(Section.combine(preambleSections..add(processed)));
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              }
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              block.clear();
            } else if (trimmedLine == _dartDocPrefix) {
              block.add('');
            } else {
              final int index = line.indexOf(_dartDocPrefixWithSpace);
              if (index < 0) {
                throw SampleCheckerException(
                  'Dart section inexplicably did not contain "$_dartDocPrefixWithSpace" prefix.',
                  file: relativeFilePath,
                  line: lineNumber,
                );
              }
              block.add(line.substring(index + 4));
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            }
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          } else if (_codeBlockStartRegex.hasMatch(trimmedLine)) {
            assert(block.isEmpty);
            startLine = Line(
              '',
              filename: relativeFilePath,
              line: lineNumber + 1,
              indent: line.indexOf(_dartDocPrefixWithSpace) + _dartDocPrefixWithSpace.length,
            );
            inDart = true;
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          }
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        }
        if (!inSampleSection) {
          final Match sampleMatch = _dartDocSampleBeginRegex.firstMatch(trimmedLine);
          if (line == '// Examples can assume:') {
            assert(block.isEmpty);
            startLine = Line('', filename: relativeFilePath, line: lineNumber + 1, indent: 3);
            inPreamble = true;
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          } else if (sampleMatch != null) {
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            inSnippet = sampleMatch != null && (sampleMatch[1] == 'sample' || sampleMatch[1] == 'dartpad');
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            if (inSnippet) {
              startLine = Line(
                '',
                filename: relativeFilePath,
                line: lineNumber + 1,
                indent: line.indexOf(_dartDocPrefixWithSpace) + _dartDocPrefixWithSpace.length,
              );
              if (sampleMatch[2] != null) {
                // There are arguments to the snippet tool to keep track of.
                snippetArgs = _splitUpQuotedArgs(sampleMatch[2]).toList();
              } else {
                snippetArgs = <String>[];
              }
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            }
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            inSampleSection = !inSnippet;
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          } else if (RegExp(r'///\s*#+\s+[Ss]ample\s+[Cc]ode:?$').hasMatch(trimmedLine)) {
            throw SampleCheckerException(
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              "Found deprecated '## Sample code' section: use {@tool snippet}...{@end-tool} instead.",
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              file: relativeFilePath,
              line: lineNumber,
            );
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          }
        }
      }
    }
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    print('Found ${sections.length} sample code sections.');
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    for (final Section section in sections) {
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      sectionMap[_writeSection(section).path] = section;
    }
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    for (final Sample sample in samples) {
      final File snippetFile = _writeSample(sample);
      sample.contents = snippetFile.readAsLinesSync();
      sampleMap[snippetFile.absolute.path] = sample;
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    }
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  }

  /// Helper to process arguments given as a (possibly quoted) string.
  ///
  /// First, this will split the given [argsAsString] into separate arguments,
  /// taking any quoting (either ' or " are accepted) into account, including
  /// handling backslash-escaped quotes.
  ///
  /// Then, it will prepend "--" to any args that start with an identifier
  /// followed by an equals sign, allowing the argument parser to treat any
  /// "foo=bar" argument as "--foo=bar" (which is a dartdoc-ism).
  Iterable<String> _splitUpQuotedArgs(String argsAsString) {
    // Regexp to take care of splitting arguments, and handling the quotes
    // around arguments, if any.
    //
    // Match group 1 is the "foo=" (or "--foo=") part of the option, if any.
    // Match group 2 contains the quote character used (which is discarded).
    // Match group 3 is a quoted arg, if any, without the quotes.
    // Match group 4 is the unquoted arg, if any.
    final RegExp argMatcher = RegExp(r'([a-zA-Z\-_0-9]+=)?' // option name
        r'(?:' // Start a new non-capture group for the two possibilities.
        r'''(["'])((?:\\{2})*|(?:.*?[^\\](?:\\{2})*))\2|''' // with quotes.
        r'([^ ]+))'); // without quotes.
    final Iterable<Match> matches = argMatcher.allMatches(argsAsString);

    // Remove quotes around args, and if convertToArgs is true, then for any
    // args that look like assignments (start with valid option names followed
    // by an equals sign), add a "--" in front so that they parse as options.
    return matches.map<String>((Match match) {
      String option = '';
      if (match[1] != null && !match[1].startsWith('-')) {
        option = '--';
      }
      if (match[2] != null) {
        // This arg has quotes, so strip them.
        return '$option${match[1] ?? ''}${match[3] ?? ''}${match[4] ?? ''}';
      }
      return '$option${match[0]}';
    });
  }

  /// Creates the configuration files necessary for the analyzer to consider
  /// the temporary director a package, and sets which lint rules to enforce.
  void _createConfigurationFiles(Directory directory) {
    final File pubSpec = File(path.join(directory.path, 'pubspec.yaml'))..createSync(recursive: true);
    final File analysisOptions = File(path.join(directory.path, 'analysis_options.yaml'))..createSync(recursive: true);
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    pubSpec.writeAsStringSync('''
name: analyze_sample_code
dependencies:
  flutter:
    sdk: flutter
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  flutter_test:
    sdk: flutter
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''');
    analysisOptions.writeAsStringSync('''
linter:
  rules:
    - unnecessary_const
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    - unnecessary_new
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''');
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  }

  /// Writes out a sample section to the disk and returns the file.
  File _writeSection(Section section) {
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    final String sectionId = _createNameFromSource('snippet', section.start.filename, section.start.line);
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    final File outputFile = File(path.join(_tempDirectory.path, '$sectionId.dart'))..createSync(recursive: true);
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    final List<Line> mainContents = <Line>[
      ...headers,
      const Line(''),
      Line('// From: ${section.start.filename}:${section.start.line}'),
      ...section.code,
    ];
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    outputFile.writeAsStringSync(mainContents.map<String>((Line line) => line.code).join('\n'));
    return outputFile;
  }

  /// Invokes the analyzer on the given [directory] and returns the stdout.
  List<String> _runAnalyzer(Directory directory) {
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    print('Starting analysis of code samples.');
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    _createConfigurationFiles(directory);
    final ProcessResult result = Process.runSync(
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      _flutter,
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      <String>['--no-wrap', 'analyze', '--no-preamble', '--no-congratulate', '.'],
      workingDirectory: directory.absolute.path,
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    );
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    final List<String> stderr = result.stderr.toString().trim().split('\n');
    final List<String> stdout = result.stdout.toString().trim().split('\n');
    // Check out the stderr to see if the analyzer had it's own issues.
    if (stderr.isNotEmpty && (stderr.first.contains(' issues found. (ran in ') || stderr.first.contains(' issue found. (ran in '))) {
      // The "23 issues found" message goes onto stderr, which is concatenated first.
      stderr.removeAt(0);
      // If there's an "issues found" message, we put a blank line on stdout before it.
      if (stderr.isNotEmpty && stderr.last.isEmpty) {
        stderr.removeLast();
      }
    }
    if (stderr.isNotEmpty) {
      throw 'Cannot analyze dartdocs; unexpected error output:\n$stderr';
    }
    if (stdout.isNotEmpty && stdout.first == 'Building flutter tool...') {
      stdout.removeAt(0);
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    }
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    if (stdout.isNotEmpty && stdout.first.startsWith('Running "flutter pub get" in ')) {
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      stdout.removeAt(0);
    }
    _exitCode = result.exitCode;
    return stdout;
  }

  /// Starts the analysis phase of checking the samples by invoking the analyzer
  /// and parsing its output to create a map of filename to [AnalysisError]s.
  Map<String, List<AnalysisError>> _analyze(
    Directory directory,
    Map<String, Section> sections,
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    Map<String, Sample> samples,
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  ) {
    final List<String> errors = _runAnalyzer(directory);
    final Map<String, List<AnalysisError>> analysisErrors = <String, List<AnalysisError>>{};
    void addAnalysisError(File file, AnalysisError error) {
      if (analysisErrors.containsKey(file.path)) {
        analysisErrors[file.path].add(error);
      } else {
        analysisErrors[file.path] = <AnalysisError>[error];
      }
    }

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    final String kBullet = Platform.isWindows ? ' - ' : ' • ';
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    // RegExp to match an error output line of the analyzer.
    final RegExp errorPattern = RegExp(
      '^ +([a-z]+)$kBullet(.+)$kBullet(.+):([0-9]+):([0-9]+)$kBullet([-a-z_]+)\$',
      caseSensitive: false,
    );
    bool unknownAnalyzerErrors = false;
    final int headerLength = headers.length + 2;
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    for (final String error in errors) {
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      final Match parts = errorPattern.matchAsPrefix(error);
      if (parts != null) {
        final String message = parts[2];
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        final File file = File(path.join(_tempDirectory.path, parts[3]));
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        final List<String> fileContents = file.readAsLinesSync();
        final bool isSnippet = path.basename(file.path).startsWith('snippet.');
        final bool isSample = path.basename(file.path).startsWith('sample.');
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        final String line = parts[4];
        final String column = parts[5];
        final String errorCode = parts[6];
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        final int lineNumber = int.parse(line, radix: 10) - (isSnippet ? headerLength : 0);
591
        final int columnNumber = int.parse(column, radix: 10);
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        if (lineNumber < 0 && errorCode == 'unused_import') {
          // We don't care about unused imports.
          continue;
595
        }
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        // For when errors occur outside of the things we're trying to analyze.
        if (!isSnippet && !isSample) {
          addAnalysisError(
            file,
            AnalysisError(
              lineNumber,
              columnNumber,
              message,
              errorCode,
              Line(
                '',
                filename: file.path,
                line: lineNumber,
              ),
            ),
          );
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          throw SampleCheckerException(
            'Cannot analyze dartdocs; analysis errors exist: $error',
            file: file.path,
            line: lineNumber,
          );
618
        }
619

620
        if (errorCode == 'unused_element' || errorCode == 'unused_local_variable') {
621
          // We don't really care if sample code isn't used!
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          continue;
        }
624
        if (isSample) {
625 626 627 628 629 630 631 632
          addAnalysisError(
            file,
            AnalysisError(
              lineNumber,
              columnNumber,
              message,
              errorCode,
              null,
633
              sample: samples[file.path],
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            ),
          );
        } else {
          if (lineNumber < 1 || lineNumber > fileContents.length) {
            addAnalysisError(
              file,
              AnalysisError(
                lineNumber,
                columnNumber,
                message,
                errorCode,
                Line('', filename: file.path, line: lineNumber),
              ),
            );
648
            throw SampleCheckerException('Failed to parse error message: $error', file: file.path, line: lineNumber);
649 650 651
          }

          final Section actualSection = sections[file.path];
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          if (actualSection == null) {
            throw SampleCheckerException(
              "Unknown section for ${file.path}. Maybe the temporary directory wasn't empty?",
              file: file.path,
              line: lineNumber,
            );
          }
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          final Line actualLine = actualSection.code[lineNumber - 1];

661
          if (actualLine?.filename == null) {
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            if (errorCode == 'missing_identifier' && lineNumber > 1) {
              if (fileContents[lineNumber - 2].endsWith(',')) {
                final Line actualLine = sections[file.path].code[lineNumber - 2];
                addAnalysisError(
                  file,
                  AnalysisError(
                    actualLine.line,
                    actualLine.indent + fileContents[lineNumber - 2].length - 1,
                    'Unexpected comma at end of sample code.',
                    errorCode,
                    actualLine,
                  ),
                );
              }
            } else {
              addAnalysisError(
                file,
                AnalysisError(
                  lineNumber - 1,
                  columnNumber,
                  message,
                  errorCode,
                  actualLine,
                ),
              );
            }
688
          } else {
689 690 691 692 693 694 695 696 697 698
            addAnalysisError(
              file,
              AnalysisError(
                actualLine.line,
                actualLine.indent + columnNumber,
                message,
                errorCode,
                actualLine,
              ),
            );
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          }
        }
      } else {
702 703
        stderr.writeln('Analyzer output: $error');
        unknownAnalyzerErrors = true;
704 705
      }
    }
706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721
    if (_exitCode == 1 && analysisErrors.isEmpty && !unknownAnalyzerErrors) {
      _exitCode = 0;
    }
    if (_exitCode == 0) {
      print('No analysis errors in samples!');
      assert(analysisErrors.isEmpty);
    }
    return analysisErrors;
  }

  /// Process one block of sample code (the part inside of "```" markers).
  /// Splits any sections denoted by "// ..." into separate blocks to be
  /// processed separately. Uses a primitive heuristic to make sample blocks
  /// into valid Dart code.
  Section _processBlock(Line line, List<String> block) {
    if (block.isEmpty) {
722
      throw SampleCheckerException('$line: Empty ```dart block in sample code.');
723
    }
724
    if (block.first.startsWith('new ') || block.first.startsWith(_constructorRegExp)) {
725 726 727 728 729 730 731 732 733 734
      _expressionId += 1;
      return Section.surround(line, 'dynamic expression$_expressionId = ', block.toList(), ';');
    } else if (block.first.startsWith('await ')) {
      _expressionId += 1;
      return Section.surround(line, 'Future<void> expression$_expressionId() async { ', block.toList(), ' }');
    } else if (block.first.startsWith('class ') || block.first.startsWith('enum ')) {
      return Section.fromStrings(line, block.toList());
    } else if ((block.first.startsWith('_') || block.first.startsWith('final ')) && block.first.contains(' = ')) {
      _expressionId += 1;
      return Section.surround(line, 'void expression$_expressionId() { ', block.toList(), ' }');
735
    } else {
736 737 738 739 740 741 742 743 744
      final List<String> buffer = <String>[];
      int subblocks = 0;
      Line subline;
      final List<Section> subsections = <Section>[];
      for (int index = 0; index < block.length; index += 1) {
        // Each section of the dart code that is either split by a blank line, or with '// ...' is
        // treated as a separate code block.
        if (block[index] == '' || block[index] == '// ...') {
          if (subline == null)
745 746
            throw SampleCheckerException('${Line('', filename: line.filename, line: line.line + index, indent: line.indent)}: '
                'Unexpected blank line or "// ..." line near start of subblock in sample code.');
747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772
          subblocks += 1;
          subsections.add(_processBlock(subline, buffer));
          buffer.clear();
          assert(buffer.isEmpty);
          subline = null;
        } else if (block[index].startsWith('// ')) {
          if (buffer.length > 1) // don't include leading comments
            buffer.add('/${block[index]}'); // so that it doesn't start with "// " and get caught in this again
        } else {
          subline ??= Line(
            block[index],
            filename: line.filename,
            line: line.line + index,
            indent: line.indent,
          );
          buffer.add(block[index]);
        }
      }
      if (subblocks > 0) {
        if (subline != null) {
          subsections.add(_processBlock(subline, buffer));
        }
        // Combine all of the subsections into one section, now that they've been processed.
        return Section.combine(subsections);
      } else {
        return Section.fromStrings(line, block.toList());
773
      }
774 775 776 777
    }
  }
}

778 779 780 781 782 783 784 785 786
/// A class to represent a line of input code.
class Line {
  const Line(this.code, {this.filename, this.line, this.indent});
  final String filename;
  final int line;
  final int indent;
  final String code;

  String toStringWithColumn(int column) {
787
    if (column != null && indent != null) {
788 789 790 791 792 793 794 795 796
      return '$filename:$line:${column + indent}: $code';
    }
    return toString();
  }

  @override
  String toString() => '$filename:$line: $code';
}

797
/// A class to represent a section of sample code, marked by "{@tool snippet}...{@end-tool}".
798 799 800
class Section {
  const Section(this.code);
  factory Section.combine(List<Section> sections) {
801 802 803
    final List<Line> code = sections
      .expand((Section section) => section.code)
      .toList();
804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833
    return Section(code);
  }
  factory Section.fromStrings(Line firstLine, List<String> code) {
    final List<Line> codeLines = <Line>[];
    for (int i = 0; i < code.length; ++i) {
      codeLines.add(
        Line(
          code[i],
          filename: firstLine.filename,
          line: firstLine.line + i,
          indent: firstLine.indent,
        ),
      );
    }
    return Section(codeLines);
  }
  factory Section.surround(Line firstLine, String prefix, List<String> code, String postfix) {
    assert(prefix != null);
    assert(postfix != null);
    final List<Line> codeLines = <Line>[];
    for (int i = 0; i < code.length; ++i) {
      codeLines.add(
        Line(
          code[i],
          filename: firstLine.filename,
          line: firstLine.line + i,
          indent: firstLine.indent,
        ),
      );
    }
834 835 836 837 838
    return Section(<Line>[
      Line(prefix),
      ...codeLines,
      Line(postfix),
    ]);
839 840 841 842 843
  }
  Line get start => code.firstWhere((Line line) => line.filename != null);
  final List<Line> code;
}

844 845 846
/// A class to represent a sample in the dartdoc comments, marked by
/// "{@tool sample ...}...{@end-tool}". Samples are processed separately from
/// regular snippets, because they must be injected into templates in order to be
847
/// analyzed.
848 849
class Sample {
  Sample({this.start, List<String> input, List<String> args, this.serial}) {
850 851
    this.input = input.toList();
    this.args = args.toList();
852 853 854 855 856 857 858 859 860
  }
  final Line start;
  final int serial;
  List<String> input;
  List<String> args;
  List<String> contents;

  @override
  String toString() {
861
    final StringBuffer buf = StringBuffer('sample ${args.join(' ')}\n');
862
    int count = start.line;
863
    for (final String line in input) {
864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880
      buf.writeln(' ${count.toString().padLeft(4, ' ')}: $line');
      count++;
    }
    return buf.toString();
  }
}

/// A class representing an analysis error along with the context of the error.
///
/// Changes how it converts to a string based on the source of the error.
class AnalysisError {
  const AnalysisError(
    this.line,
    this.column,
    this.message,
    this.errorCode,
    this.source, {
881
    this.sample,
882 883 884 885 886 887 888
  });

  final int line;
  final int column;
  final String message;
  final String errorCode;
  final Line source;
889
  final Sample sample;
890 891 892 893 894

  @override
  String toString() {
    if (source != null) {
      return '${source.toStringWithColumn(column)}\n>>> $message ($errorCode)';
895 896 897
    } else if (sample != null) {
      return 'In sample starting at '
          '${sample.start.filename}:${sample.start.line}:${sample.contents[line - 1]}\n'
898
          '>>> $message ($errorCode)';
899
    } else {
900
      return '<source unknown>:$line:$column\n>>> $message ($errorCode)';
901 902 903
    }
  }
}