pkg/analysis_server/lib/src/domain_completion.dart - sdk.git - Git at Google

 // 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 'dart:async';

 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/collections.dart';
 import 'package:analysis_server/src/domain_abstract.dart';
 import 'package:analysis_server/src/domains/completion/available_suggestions.dart';
 import 'package:analysis_server/src/plugin/plugin_manager.dart';
 import 'package:analysis_server/src/provisional/completion/completion_core.dart';
 import 'package:analysis_server/src/services/completion/completion_core.dart';
 import 'package:analysis_server/src/services/completion/completion_performance.dart';
 import 'package:analysis_server/src/services/completion/dart/completion_manager.dart';
 import 'package:analysis_server/src/services/completion/token_details/token_detail_builder.dart';
 import 'package:analyzer/dart/analysis/results.dart';
 import 'package:analyzer/dart/analysis/session.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart' as plugin;
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:analyzer_plugin/protocol/protocol_constants.dart' as plugin;
 import 'package:analyzer_plugin/protocol/protocol_generated.dart' as plugin;
 import 'package:analyzer_plugin/utilities/change_builder/change_builder_dart.dart';

 /**
  * Instances of the class [CompletionDomainHandler] implement a [RequestHandler]
  * that handles requests in the completion domain.
  */
 class CompletionDomainHandler extends AbstractRequestHandler {
   /**
    * The maximum number of performance measurements to keep.
    */
   static const int performanceListMaxLength = 50;

   /**
    * The completion services that the client is currently subscribed.
    */
   final Set<CompletionService> subscriptions = Set<CompletionService>();

   /**
    * The next completion response id.
    */
   int _nextCompletionId = 0;

   /**
    * Code completion performance for the last completion operation.
    */
   CompletionPerformance performance;

   /**
    * A list of code completion performance measurements for the latest
    * completion operation up to [performanceListMaxLength] measurements.
    */
   final RecentBuffer<CompletionPerformance> performanceList =
       new RecentBuffer<CompletionPerformance>(performanceListMaxLength);

   /**
    * The current request being processed or `null` if none.
    */
   CompletionRequestImpl _currentRequest;

   /**
    * The identifiers of the latest `getSuggestionDetails` request.
    * We use it to abort previous requests.
    */
   int _latestGetSuggestionDetailsId = 0;

   /**
    * Initialize a new request handler for the given [server].
    */
   CompletionDomainHandler(AnalysisServer server) : super(server);

   /**
    * Compute completion results for the given request and append them to the stream.
    * Clients should not call this method directly as it is automatically called
    * when a client listens to the stream returned by [results].
    * Subclasses should override this method, append at least one result
    * to the [controller], and close the controller stream once complete.
    */
   Future<CompletionResult> computeSuggestions(
     CompletionRequestImpl request,
     CompletionGetSuggestionsParams params,
     Set<ElementKind> includedElementKinds,
     List<IncludedSuggestionRelevanceTag> includedSuggestionRelevanceTags,
   ) async {
     // TODO(brianwilkerson) Determine whether this await is necessary.
     await null;
     //
     // Allow plugins to start computing fixes.
     //
     Map<PluginInfo, Future<plugin.Response>> pluginFutures;
     plugin.CompletionGetSuggestionsParams requestParams;
     String file = params.file;
     int offset = params.offset;
     AnalysisDriver driver = server.getAnalysisDriver(file);
     if (driver != null) {
       requestParams = new plugin.CompletionGetSuggestionsParams(file, offset);
       pluginFutures = server.pluginManager
           .broadcastRequest(requestParams, contextRoot: driver.contextRoot);
     }
     //
     // Compute completions generated by server.
     //
     List<CompletionSuggestion> suggestions = <CompletionSuggestion>[];
     if (request.result != null) {
       const COMPUTE_SUGGESTIONS_TAG = 'computeSuggestions';
       performance.logStartTime(COMPUTE_SUGGESTIONS_TAG);

       var manager = new DartCompletionManager(
         includedElementKinds: includedElementKinds,
         includedSuggestionRelevanceTags: includedSuggestionRelevanceTags,
       );

       String contributorTag = 'computeSuggestions - ${manager.runtimeType}';
       performance.logStartTime(contributorTag);
       try {
         suggestions.addAll(await manager.computeSuggestions(request));
       } on AbortCompletion {
         suggestions.clear();
       }
       performance.logElapseTime(contributorTag);
       performance.logElapseTime(COMPUTE_SUGGESTIONS_TAG);
     }
     // TODO (danrubel) if request is obsolete (processAnalysisRequest returns
     // false) then send empty results

     //
     // Add the fixes produced by plugins to the server-generated fixes.
     //
     if (pluginFutures != null) {
       List<plugin.Response> responses = await waitForResponses(pluginFutures,
           requestParameters: requestParams);
       for (plugin.Response response in responses) {
         plugin.CompletionGetSuggestionsResult result =
             new plugin.CompletionGetSuggestionsResult.fromResponse(response);
         if (result.results != null && result.results.isNotEmpty) {
           if (suggestions.isEmpty) {
             request.replacementOffset = result.replacementOffset;
             request.replacementLength = result.replacementLength;
           } else if (request.replacementOffset != result.replacementOffset &&
               request.replacementLength != result.replacementLength) {
             server.instrumentationService
                 .logError('Plugin completion-results dropped due to conflicting'
                     ' replacement offset/length: ${result.toJson()}');
             continue;
           }
           suggestions.addAll(result.results);
         }
       }
     }
     //
     // Return the result.
     //
     return new CompletionResult(
         request.replacementOffset, request.replacementLength, suggestions);
   }

   /**
    * Process a `completion.getSuggestionDetails` request.
    */
   void getSuggestionDetails(Request request) async {
     var params = CompletionGetSuggestionDetailsParams.fromRequest(request);

     var file = params.file;
     if (server.sendResponseErrorIfInvalidFilePath(request, file)) {
       return;
     }

     var libraryId = params.id;
     var library = server.declarationsTracker.getLibrary(libraryId);
     if (library == null) {
       server.sendResponse(Response.invalidParameter(
         request,
         'libraryId',
         'No such library: $libraryId',
       ));
       return;
     }

     // The label might be `MyEnum.myValue`, but we import only `MyEnum`.
     var requestedName = params.label;
     if (requestedName.contains('.')) {
       requestedName = requestedName.substring(
         0,
         requestedName.indexOf('.'),
       );
     }

     const timeout = Duration(milliseconds: 1000);
     var timer = Stopwatch()..start();
     var id = ++_latestGetSuggestionDetailsId;
     while (id == _latestGetSuggestionDetailsId && timer.elapsed < timeout) {
       try {
         var analysisDriver = server.getAnalysisDriver(file);
         var session = analysisDriver.currentSession;

         var fileElement = await session.getUnitElement(file);
         var libraryPath = fileElement.element.librarySource.fullName;

         var resolvedLibrary = await session.getResolvedLibrary(libraryPath);
         var requestedLibraryElement = await session.getLibraryByUri(
           library.uriStr,
         );

         var requestedElement =
             requestedLibraryElement.exportNamespace.get(requestedName);
         if (requestedElement == null) {
           server.sendResponse(Response.invalidParameter(
             request,
             'label',
             'No such element: $requestedName',
           ));
           return;
         }

         var completion = params.label;
         var builder = DartChangeBuilder(session);
         await builder.addFileEdit(libraryPath, (builder) {
           var result = builder.importLibraryElement(
             targetLibrary: resolvedLibrary,
             targetPath: libraryPath,
             targetOffset: params.offset,
             requestedLibrary: requestedLibraryElement,
             requestedElement: requestedElement,
           );
           if (result.prefix != null) {
             completion = '${result.prefix}.$completion';
           }
         });

         server.sendResponse(
           CompletionGetSuggestionDetailsResult(
             completion,
             change: builder.sourceChange,
           ).toResponse(request.id),
         );
         return;
       } on InconsistentAnalysisException {
         // Loop around to try again.
       }
     }

     // Timeout or abort, send the empty response.
     server.sendResponse(
       CompletionGetSuggestionDetailsResult('').toResponse(request.id),
     );
   }

   @override
   Response handleRequest(Request request) {
     return runZoned(() {
       String requestName = request.method;

       if (requestName == COMPLETION_REQUEST_GET_SUGGESTION_DETAILS) {
         getSuggestionDetails(request);
         return Response.DELAYED_RESPONSE;
       } else if (requestName == COMPLETION_REQUEST_GET_SUGGESTIONS) {
         processRequest(request);
         return Response.DELAYED_RESPONSE;
       } else if (requestName == COMPLETION_REQUEST_LIST_TOKEN_DETAILS) {
         listTokenDetails(request);
         return Response.DELAYED_RESPONSE;
       } else if (requestName == COMPLETION_REQUEST_SET_SUBSCRIPTIONS) {
         return setSubscriptions(request);
       }
       return null;
     }, onError: (exception, stackTrace) {
       server.sendServerErrorNotification(
           'Failed to handle completion domain request: ${request.toJson()}',
           exception,
           stackTrace);
     });
   }

   void ifMatchesRequestClear(CompletionRequest completionRequest) {
     if (_currentRequest == completionRequest) {
       _currentRequest = null;
     }
   }

   /**
    * Process a `completion.listTokenDetails` request.
    */
   Future<void> listTokenDetails(Request request) async {
     CompletionListTokenDetailsParams params =
         CompletionListTokenDetailsParams.fromRequest(request);

     String file = params.file;
     if (server.sendResponseErrorIfInvalidFilePath(request, file)) {
       return;
     }

     AnalysisDriver analysisDriver = server.getAnalysisDriver(file);
     if (analysisDriver == null) {
       server.sendResponse(Response.invalidParameter(
         request,
         'file',
         'File is not being analyzed: $file',
       ));
     }
     AnalysisSession session = analysisDriver.currentSession;
     ResolvedUnitResult result = await session.getResolvedUnit(file);
     if (result.state != ResultState.VALID) {
       server.sendResponse(Response.invalidParameter(
         request,
         'file',
         'File does not exist or cannot be read: $file',
       ));
     }

     TokenDetailBuilder builder = new TokenDetailBuilder();
     builder.visitNode(result.unit);
     server.sendResponse(
       CompletionListTokenDetailsResult(builder.details).toResponse(request.id),
     );
   }

   /**
    * Process a `completion.getSuggestions` request.
    */
   Future<void> processRequest(Request request) async {
     // TODO(brianwilkerson) Determine whether this await is necessary.
     await null;
     performance = new CompletionPerformance();

     // extract and validate params
     CompletionGetSuggestionsParams params =
         new CompletionGetSuggestionsParams.fromRequest(request);
     String file = params.file;
     int offset = params.offset;

     if (server.sendResponseErrorIfInvalidFilePath(request, file)) {
       return;
     }

     ResolvedUnitResult resolvedUnit = await server.getResolvedUnit(file);
     if (resolvedUnit?.state == ResultState.VALID) {
       if (offset < 0 || offset > resolvedUnit.content.length) {
         server.sendResponse(new Response.invalidParameter(
             request,
             'params.offset',
             'Expected offset between 0 and source length inclusive,'
             ' but found $offset'));
         return;
       }

       recordRequest(performance, file, resolvedUnit.content, offset);
     }
     CompletionRequestImpl completionRequest =
         new CompletionRequestImpl(resolvedUnit, offset, performance);

     String completionId = (_nextCompletionId++).toString();

     setNewRequest(completionRequest);

     // initial response without results
     server.sendResponse(new CompletionGetSuggestionsResult(completionId)
         .toResponse(request.id));

     // If the client opted into using available suggestion sets,
     // create the kinds set, so signal the completion manager about opt-in.
     Set<ElementKind> includedElementKinds;
     List<IncludedSuggestionRelevanceTag> includedSuggestionRelevanceTags;
     if (subscriptions.contains(CompletionService.AVAILABLE_SUGGESTION_SETS)) {
       includedElementKinds = Set<ElementKind>();
       includedSuggestionRelevanceTags = <IncludedSuggestionRelevanceTag>[];
     }

     // Compute suggestions in the background
     computeSuggestions(
       completionRequest,
       params,
       includedElementKinds,
       includedSuggestionRelevanceTags,
     ).then((CompletionResult result) {
       List<IncludedSuggestionSet> includedSuggestionSets;
       if (includedElementKinds != null && resolvedUnit != null) {
         includedSuggestionSets = computeIncludedSetList(
           server.declarationsTracker,
           resolvedUnit,
         );
       } else {
         includedSuggestionSets = [];
       }

       const SEND_NOTIFICATION_TAG = 'send notification';
       performance.logStartTime(SEND_NOTIFICATION_TAG);
       sendCompletionNotification(
         completionId,
         result.replacementOffset,
         result.replacementLength,
         result.suggestions,
         includedSuggestionSets,
         includedElementKinds?.toList(),
         includedSuggestionRelevanceTags,
       );
       performance.logElapseTime(SEND_NOTIFICATION_TAG);

       performance.notificationCount = 1;
       performance.logFirstNotificationComplete('notification 1 complete');
       performance.suggestionCountFirst = result.suggestions.length;
       performance.suggestionCountLast = result.suggestions.length;
       performance.complete();
     }).whenComplete(() {
       ifMatchesRequestClear(completionRequest);
     });
   }

   /**
    * If tracking code completion performance over time, then
    * record addition information about the request in the performance record.
    */
   void recordRequest(CompletionPerformance performance, String path,
       String content, int offset) {
     performance.path = path;
     if (performanceListMaxLength == 0) {
       return;
     }
     performance.setContentsAndOffset(content, offset);
     performanceList.add(performance);
   }

   /**
    * Send completion notification results.
    */
   void sendCompletionNotification(
     String completionId,
     int replacementOffset,
     int replacementLength,
     Iterable<CompletionSuggestion> results,
     List<IncludedSuggestionSet> includedSuggestionSets,
     List<ElementKind> includedElementKinds,
     List<IncludedSuggestionRelevanceTag> includedSuggestionRelevanceTags,
   ) {
     server.sendNotification(
       new CompletionResultsParams(
         completionId,
         replacementOffset,
         replacementLength,
         results,
         true,
         includedSuggestionSets: includedSuggestionSets,
         includedElementKinds: includedElementKinds,
         includedSuggestionRelevanceTags: includedSuggestionRelevanceTags,
       ).toNotification(),
     );
   }

   void setNewRequest(CompletionRequest completionRequest) {
     _abortCurrentRequest();
     _currentRequest = completionRequest;
   }

   /**
    * Implement the 'completion.setSubscriptions' request.
    */
   Response setSubscriptions(Request request) {
     var params = CompletionSetSubscriptionsParams.fromRequest(request);

     subscriptions.clear();
     subscriptions.addAll(params.subscriptions);

     if (subscriptions.contains(CompletionService.AVAILABLE_SUGGESTION_SETS)) {
       server.createDeclarationsTracker((change) {
         server.sendNotification(
           createCompletionAvailableSuggestionsNotification(change),
         );
       });
     } else {
       server.disposeDeclarationsTracker();
     }

     return CompletionSetSubscriptionsResult().toResponse(request.id);
   }

   /**
    * Abort the current completion request, if any.
    */
   void _abortCurrentRequest() {
     if (_currentRequest != null) {
       _currentRequest.abort();
       _currentRequest = null;
     }
   }
 }

 /**
  * The result of computing suggestions for code completion.
  */
 class CompletionResult {
   /**
    * The length of the text to be replaced if the remainder of the identifier
    * containing the cursor is to be replaced when the suggestion is applied
    * (that is, the number of characters in the existing identifier).
    */
   final int replacementLength;

   /**
    * The offset of the start of the text to be replaced. This will be different
    * than the offset used to request the completion suggestions if there was a
    * portion of an identifier before the original offset. In particular, the
    * replacementOffset will be the offset of the beginning of said identifier.
    */
   final int replacementOffset;

   /**
    * The suggested completions.
    */
   final List<CompletionSuggestion> suggestions;

   CompletionResult(
       this.replacementOffset, this.replacementLength, this.suggestions);
 }
	// 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 'dart:async';

	import 'package:analysis_server/protocol/protocol.dart';
	import 'package:analysis_server/protocol/protocol_constants.dart';
	import 'package:analysis_server/protocol/protocol_generated.dart';
	import 'package:analysis_server/src/analysis_server.dart';
	import 'package:analysis_server/src/collections.dart';
	import 'package:analysis_server/src/domain_abstract.dart';
	import 'package:analysis_server/src/domains/completion/available_suggestions.dart';
	import 'package:analysis_server/src/plugin/plugin_manager.dart';
	import 'package:analysis_server/src/provisional/completion/completion_core.dart';
	import 'package:analysis_server/src/services/completion/completion_core.dart';
	import 'package:analysis_server/src/services/completion/completion_performance.dart';
	import 'package:analysis_server/src/services/completion/dart/completion_manager.dart';
	import 'package:analysis_server/src/services/completion/token_details/token_detail_builder.dart';
	import 'package:analyzer/dart/analysis/results.dart';
	import 'package:analyzer/dart/analysis/session.dart';
	import 'package:analyzer/src/dart/analysis/driver.dart';
	import 'package:analyzer_plugin/protocol/protocol.dart' as plugin;
	import 'package:analyzer_plugin/protocol/protocol_common.dart';
	import 'package:analyzer_plugin/protocol/protocol_constants.dart' as plugin;
	import 'package:analyzer_plugin/protocol/protocol_generated.dart' as plugin;
	import 'package:analyzer_plugin/utilities/change_builder/change_builder_dart.dart';

	/**
	* Instances of the class [CompletionDomainHandler] implement a [RequestHandler]
	* that handles requests in the completion domain.
	*/
	class CompletionDomainHandler extends AbstractRequestHandler {
	/**
	* The maximum number of performance measurements to keep.
	*/
	static const int performanceListMaxLength = 50;

	/**
	* The completion services that the client is currently subscribed.
	*/
	final Set<CompletionService> subscriptions = Set<CompletionService>();

	/**
	* The next completion response id.
	*/
	int _nextCompletionId = 0;

	/**
	* Code completion performance for the last completion operation.
	*/
	CompletionPerformance performance;

	/**
	* A list of code completion performance measurements for the latest
	* completion operation up to [performanceListMaxLength] measurements.
	*/
	final RecentBuffer<CompletionPerformance> performanceList =
	new RecentBuffer<CompletionPerformance>(performanceListMaxLength);

	/**
	* The current request being processed or `null` if none.
	*/
	CompletionRequestImpl _currentRequest;

	/**
	* The identifiers of the latest `getSuggestionDetails` request.
	* We use it to abort previous requests.
	*/
	int _latestGetSuggestionDetailsId = 0;

	/**
	* Initialize a new request handler for the given [server].
	*/
	CompletionDomainHandler(AnalysisServer server) : super(server);

	/**
	* Compute completion results for the given request and append them to the stream.
	* Clients should not call this method directly as it is automatically called
	* when a client listens to the stream returned by [results].
	* Subclasses should override this method, append at least one result
	* to the [controller], and close the controller stream once complete.
	*/
	Future<CompletionResult> computeSuggestions(
	CompletionRequestImpl request,
	CompletionGetSuggestionsParams params,
	Set<ElementKind> includedElementKinds,
	List<IncludedSuggestionRelevanceTag> includedSuggestionRelevanceTags,
	) async {
	// TODO(brianwilkerson) Determine whether this await is necessary.
	await null;
	//
	// Allow plugins to start computing fixes.
	//
	Map<PluginInfo, Future<plugin.Response>> pluginFutures;
	plugin.CompletionGetSuggestionsParams requestParams;
	String file = params.file;
	int offset = params.offset;
	AnalysisDriver driver = server.getAnalysisDriver(file);
	if (driver != null) {
	requestParams = new plugin.CompletionGetSuggestionsParams(file, offset);
	pluginFutures = server.pluginManager
	.broadcastRequest(requestParams, contextRoot: driver.contextRoot);
	}
	//
	// Compute completions generated by server.
	//
	List<CompletionSuggestion> suggestions = <CompletionSuggestion>[];
	if (request.result != null) {
	const COMPUTE_SUGGESTIONS_TAG = 'computeSuggestions';
	performance.logStartTime(COMPUTE_SUGGESTIONS_TAG);

	var manager = new DartCompletionManager(
	includedElementKinds: includedElementKinds,
	includedSuggestionRelevanceTags: includedSuggestionRelevanceTags,
	);

	String contributorTag = 'computeSuggestions - ${manager.runtimeType}';
	performance.logStartTime(contributorTag);
	try {
	suggestions.addAll(await manager.computeSuggestions(request));
	} on AbortCompletion {
	suggestions.clear();
	}
	performance.logElapseTime(contributorTag);
	performance.logElapseTime(COMPUTE_SUGGESTIONS_TAG);
	}
	// TODO (danrubel) if request is obsolete (processAnalysisRequest returns
	// false) then send empty results

	//
	// Add the fixes produced by plugins to the server-generated fixes.
	//
	if (pluginFutures != null) {
	List<plugin.Response> responses = await waitForResponses(pluginFutures,
	requestParameters: requestParams);
	for (plugin.Response response in responses) {
	plugin.CompletionGetSuggestionsResult result =
	new plugin.CompletionGetSuggestionsResult.fromResponse(response);
	if (result.results != null && result.results.isNotEmpty) {
	if (suggestions.isEmpty) {
	request.replacementOffset = result.replacementOffset;
	request.replacementLength = result.replacementLength;
	} else if (request.replacementOffset != result.replacementOffset &&
	request.replacementLength != result.replacementLength) {
	server.instrumentationService
	.logError('Plugin completion-results dropped due to conflicting'
	' replacement offset/length: ${result.toJson()}');
	continue;
	}
	suggestions.addAll(result.results);
	}
	}
	}
	//
	// Return the result.
	//
	return new CompletionResult(
	request.replacementOffset, request.replacementLength, suggestions);
	}

	/**
	* Process a `completion.getSuggestionDetails` request.
	*/
	void getSuggestionDetails(Request request) async {
	var params = CompletionGetSuggestionDetailsParams.fromRequest(request);

	var file = params.file;
	if (server.sendResponseErrorIfInvalidFilePath(request, file)) {
	return;
	}

	var libraryId = params.id;
	var library = server.declarationsTracker.getLibrary(libraryId);
	if (library == null) {
	server.sendResponse(Response.invalidParameter(
	request,
	'libraryId',
	'No such library: $libraryId',
	));
	return;
	}

	// The label might be `MyEnum.myValue`, but we import only `MyEnum`.
	var requestedName = params.label;
	if (requestedName.contains('.')) {
	requestedName = requestedName.substring(
	0,
	requestedName.indexOf('.'),
	);
	}

	const timeout = Duration(milliseconds: 1000);
	var timer = Stopwatch()..start();
	var id = ++_latestGetSuggestionDetailsId;
	while (id == _latestGetSuggestionDetailsId && timer.elapsed < timeout) {
	try {
	var analysisDriver = server.getAnalysisDriver(file);
	var session = analysisDriver.currentSession;

	var fileElement = await session.getUnitElement(file);
	var libraryPath = fileElement.element.librarySource.fullName;

	var resolvedLibrary = await session.getResolvedLibrary(libraryPath);
	var requestedLibraryElement = await session.getLibraryByUri(
	library.uriStr,
	);

	var requestedElement =
	requestedLibraryElement.exportNamespace.get(requestedName);
	if (requestedElement == null) {
	server.sendResponse(Response.invalidParameter(
	request,
	'label',
	'No such element: $requestedName',
	));
	return;
	}

	var completion = params.label;
	var builder = DartChangeBuilder(session);
	await builder.addFileEdit(libraryPath, (builder) {
	var result = builder.importLibraryElement(
	targetLibrary: resolvedLibrary,
	targetPath: libraryPath,
	targetOffset: params.offset,
	requestedLibrary: requestedLibraryElement,
	requestedElement: requestedElement,
	);
	if (result.prefix != null) {
	completion = '${result.prefix}.$completion';
	}
	});

	server.sendResponse(
	CompletionGetSuggestionDetailsResult(
	completion,
	change: builder.sourceChange,
	).toResponse(request.id),
	);
	return;
	} on InconsistentAnalysisException {
	// Loop around to try again.
	}
	}

	// Timeout or abort, send the empty response.
	server.sendResponse(
	CompletionGetSuggestionDetailsResult('').toResponse(request.id),
	);
	}

	@override
	Response handleRequest(Request request) {
	return runZoned(() {
	String requestName = request.method;

	if (requestName == COMPLETION_REQUEST_GET_SUGGESTION_DETAILS) {
	getSuggestionDetails(request);
	return Response.DELAYED_RESPONSE;
	} else if (requestName == COMPLETION_REQUEST_GET_SUGGESTIONS) {
	processRequest(request);
	return Response.DELAYED_RESPONSE;
	} else if (requestName == COMPLETION_REQUEST_LIST_TOKEN_DETAILS) {
	listTokenDetails(request);
	return Response.DELAYED_RESPONSE;
	} else if (requestName == COMPLETION_REQUEST_SET_SUBSCRIPTIONS) {
	return setSubscriptions(request);
	}
	return null;
	}, onError: (exception, stackTrace) {
	server.sendServerErrorNotification(
	'Failed to handle completion domain request: ${request.toJson()}',
	exception,
	stackTrace);
	});
	}

	void ifMatchesRequestClear(CompletionRequest completionRequest) {
	if (_currentRequest == completionRequest) {
	_currentRequest = null;
	}
	}

	/**
	* Process a `completion.listTokenDetails` request.
	*/
	Future<void> listTokenDetails(Request request) async {
	CompletionListTokenDetailsParams params =
	CompletionListTokenDetailsParams.fromRequest(request);

	String file = params.file;
	if (server.sendResponseErrorIfInvalidFilePath(request, file)) {
	return;
	}

	AnalysisDriver analysisDriver = server.getAnalysisDriver(file);
	if (analysisDriver == null) {
	server.sendResponse(Response.invalidParameter(
	request,
	'file',
	'File is not being analyzed: $file',
	));
	}
	AnalysisSession session = analysisDriver.currentSession;
	ResolvedUnitResult result = await session.getResolvedUnit(file);
	if (result.state != ResultState.VALID) {
	server.sendResponse(Response.invalidParameter(
	request,
	'file',
	'File does not exist or cannot be read: $file',
	));
	}

	TokenDetailBuilder builder = new TokenDetailBuilder();
	builder.visitNode(result.unit);
	server.sendResponse(
	CompletionListTokenDetailsResult(builder.details).toResponse(request.id),
	);
	}

	/**
	* Process a `completion.getSuggestions` request.
	*/
	Future<void> processRequest(Request request) async {
	// TODO(brianwilkerson) Determine whether this await is necessary.
	await null;
	performance = new CompletionPerformance();

	// extract and validate params
	CompletionGetSuggestionsParams params =
	new CompletionGetSuggestionsParams.fromRequest(request);
	String file = params.file;
	int offset = params.offset;

	if (server.sendResponseErrorIfInvalidFilePath(request, file)) {
	return;
	}

	ResolvedUnitResult resolvedUnit = await server.getResolvedUnit(file);
	if (resolvedUnit?.state == ResultState.VALID) {
	if (offset < 0 \|\| offset > resolvedUnit.content.length) {
	server.sendResponse(new Response.invalidParameter(
	request,
	'params.offset',
	'Expected offset between 0 and source length inclusive,'
	' but found $offset'));
	return;
	}

	recordRequest(performance, file, resolvedUnit.content, offset);
	}
	CompletionRequestImpl completionRequest =
	new CompletionRequestImpl(resolvedUnit, offset, performance);

	String completionId = (_nextCompletionId++).toString();

	setNewRequest(completionRequest);

	// initial response without results
	server.sendResponse(new CompletionGetSuggestionsResult(completionId)
	.toResponse(request.id));

	// If the client opted into using available suggestion sets,
	// create the kinds set, so signal the completion manager about opt-in.
	Set<ElementKind> includedElementKinds;
	List<IncludedSuggestionRelevanceTag> includedSuggestionRelevanceTags;
	if (subscriptions.contains(CompletionService.AVAILABLE_SUGGESTION_SETS)) {
	includedElementKinds = Set<ElementKind>();
	includedSuggestionRelevanceTags = <IncludedSuggestionRelevanceTag>[];
	}

	// Compute suggestions in the background
	computeSuggestions(
	completionRequest,
	params,
	includedElementKinds,
	includedSuggestionRelevanceTags,
	).then((CompletionResult result) {
	List<IncludedSuggestionSet> includedSuggestionSets;
	if (includedElementKinds != null && resolvedUnit != null) {
	includedSuggestionSets = computeIncludedSetList(
	server.declarationsTracker,
	resolvedUnit,
	);
	} else {
	includedSuggestionSets = [];
	}

	const SEND_NOTIFICATION_TAG = 'send notification';
	performance.logStartTime(SEND_NOTIFICATION_TAG);
	sendCompletionNotification(
	completionId,
	result.replacementOffset,
	result.replacementLength,
	result.suggestions,
	includedSuggestionSets,
	includedElementKinds?.toList(),
	includedSuggestionRelevanceTags,
	);
	performance.logElapseTime(SEND_NOTIFICATION_TAG);

	performance.notificationCount = 1;
	performance.logFirstNotificationComplete('notification 1 complete');
	performance.suggestionCountFirst = result.suggestions.length;
	performance.suggestionCountLast = result.suggestions.length;
	performance.complete();
	}).whenComplete(() {
	ifMatchesRequestClear(completionRequest);
	});
	}

	/**
	* If tracking code completion performance over time, then
	* record addition information about the request in the performance record.
	*/
	void recordRequest(CompletionPerformance performance, String path,
	String content, int offset) {
	performance.path = path;
	if (performanceListMaxLength == 0) {
	return;
	}
	performance.setContentsAndOffset(content, offset);
	performanceList.add(performance);
	}

	/**
	* Send completion notification results.
	*/
	void sendCompletionNotification(
	String completionId,
	int replacementOffset,
	int replacementLength,
	Iterable<CompletionSuggestion> results,
	List<IncludedSuggestionSet> includedSuggestionSets,
	List<ElementKind> includedElementKinds,
	List<IncludedSuggestionRelevanceTag> includedSuggestionRelevanceTags,
	) {
	server.sendNotification(
	new CompletionResultsParams(
	completionId,
	replacementOffset,
	replacementLength,
	results,
	true,
	includedSuggestionSets: includedSuggestionSets,
	includedElementKinds: includedElementKinds,
	includedSuggestionRelevanceTags: includedSuggestionRelevanceTags,
	).toNotification(),
	);
	}

	void setNewRequest(CompletionRequest completionRequest) {
	_abortCurrentRequest();
	_currentRequest = completionRequest;
	}

	/**
	* Implement the 'completion.setSubscriptions' request.
	*/
	Response setSubscriptions(Request request) {
	var params = CompletionSetSubscriptionsParams.fromRequest(request);

	subscriptions.clear();
	subscriptions.addAll(params.subscriptions);

	if (subscriptions.contains(CompletionService.AVAILABLE_SUGGESTION_SETS)) {
	server.createDeclarationsTracker((change) {
	server.sendNotification(
	createCompletionAvailableSuggestionsNotification(change),
	);
	});
	} else {
	server.disposeDeclarationsTracker();
	}

	return CompletionSetSubscriptionsResult().toResponse(request.id);
	}

	/**
	* Abort the current completion request, if any.
	*/
	void _abortCurrentRequest() {
	if (_currentRequest != null) {
	_currentRequest.abort();
	_currentRequest = null;
	}
	}
	}

	/**
	* The result of computing suggestions for code completion.
	*/
	class CompletionResult {
	/**
	* The length of the text to be replaced if the remainder of the identifier
	* containing the cursor is to be replaced when the suggestion is applied
	* (that is, the number of characters in the existing identifier).
	*/
	final int replacementLength;

	/**
	* The offset of the start of the text to be replaced. This will be different
	* than the offset used to request the completion suggestions if there was a
	* portion of an identifier before the original offset. In particular, the
	* replacementOffset will be the offset of the beginning of said identifier.
	*/
	final int replacementOffset;

	/**
	* The suggested completions.
	*/
	final List<CompletionSuggestion> suggestions;

	CompletionResult(
	this.replacementOffset, this.replacementLength, this.suggestions);
	}