pkg/analyzer/lib/src/generated/engine.dart

// Copyright (c) 2014, 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 'package:_fe_analyzer_shared/src/base/analyzer_public_api.dart';
import 'package:_fe_analyzer_shared/src/scanner/string_canonicalizer.dart';
import 'package:analyzer/dart/analysis/analysis_options.dart';
import 'package:analyzer/dart/analysis/declared_variables.dart';
import 'package:analyzer/file_system/file_system.dart';
import 'package:analyzer/instrumentation/instrumentation.dart';
import 'package:analyzer/src/generated/source.dart' show SourceFactory;

export 'package:analyzer/dart/analysis/analysis_options.dart';
export 'package:analyzer/error/listener.dart' show RecordingDiagnosticListener;
export 'package:analyzer/source/timestamped_data.dart' show TimestampedData;
export 'package:analyzer/src/analysis_options/analysis_options.dart';

/// A context in which a single analysis can be performed and incrementally
/// maintained. The context includes such information as the version of the SDK
/// being analyzed against, and how to resolve 'package:' URI's. (Both of which
/// are known indirectly through the [SourceFactory].)
///
/// An analysis context also represents the state of the analysis, which includes
/// knowing which sources have been included in the analysis (either directly or
/// indirectly) and the results of the analysis. Sources must be added and
/// removed from the context, which is also used to notify the context when
/// sources have been modified and, consequently, previously known results might
/// have been invalidated.
///
/// There are two ways to access the results of the analysis. The most common is
/// to use one of the 'get' methods to access the results. The 'get' methods have
/// the advantage that they will always return quickly, but have the disadvantage
/// that if the results are not currently available they will return either
/// nothing or in some cases an incomplete result. The second way to access
/// results is by using one of the 'compute' methods. The 'compute' methods will
/// always attempt to compute the requested results but might block the caller
/// for a significant period of time.
///
/// When results have been invalidated, have never been computed (as is the case
/// for newly added sources), or have been removed from the cache, they are
/// <b>not</b> automatically recreated. They will only be recreated if one of the
/// 'compute' methods is invoked.
///
/// However, this is not always acceptable. Some clients need to keep the
/// analysis results up-to-date. For such clients there is a mechanism that
/// allows them to incrementally perform needed analysis and get notified of the
/// consequent changes to the analysis results.
///
/// Analysis engine allows for having more than one context. This can be used,
/// for example, to perform one analysis based on the state of files on disk and
/// a separate analysis based on the state of those files in open editors. It can
/// also be used to perform an analysis based on a proposed future state, such as
/// the state after a refactoring.
@AnalyzerPublicApi(message: 'exposed by Element.context')
abstract class AnalysisContext {
  /// Return the set of declared variables used when computing constant values.
  DeclaredVariables get declaredVariables;

  /// Return the source factory used to create the sources that can be analyzed
  /// in this context.
  // ignore: analyzer_public_api_bad_type
  SourceFactory get sourceFactory;

  /// Gets the [AnalysisOptions] instance for the given [file].
  AnalysisOptions getAnalysisOptionsForFile(File file);
}

/// The entry point for the functionality provided by the analysis engine. There
/// is a single instance of this class.
class AnalysisEngine {
  /// The unique instance of this class.
  static final AnalysisEngine instance = AnalysisEngine._();

  /// The instrumentation service that is to be used by this analysis engine.
  InstrumentationService _instrumentationService =
      InstrumentationService.NULL_SERVICE;

  AnalysisEngine._();

  /// Return the instrumentation service that is to be used by this analysis
  /// engine.
  InstrumentationService get instrumentationService => _instrumentationService;

  /// Set the instrumentation service that is to be used by this analysis engine
  /// to the given [service].
  set instrumentationService(InstrumentationService? service) {
    if (service == null) {
      _instrumentationService = InstrumentationService.NULL_SERVICE;
    } else {
      _instrumentationService = service;
    }
  }

  /// Clear any caches holding on to analysis results so that a full re-analysis
  /// will be performed the next time an analysis context is created.
  void clearCaches() {
    // Ensure the string canonicalization cache size is reasonable.
    pruneStringCanonicalizationCache();
  }
}