restructure internal request to implement CompletionRequest API,

pkg/analysis_server/lib/completion/completion_core.dart

 // Copyright (c) 2015, 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.
 
 library analysis_server.completion.completion_core;
 
 import 'package:analysis_server/src/protocol.dart';
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 /**
  * An object used to produce completions for a specific error. Completion
  * contributors are long-lived objects and must not retain any state between
  * invocations of [computeSuggestions].
  *
  * Clients are expected to subtype this class when implementing plugins.
  */
 abstract class CompletionContributor {
   /**
    * Compute a list of completion suggestions based on the given completion
    * [request] and return a result that includes those suggestions. This method
    * is called after specific phases of analysis until the contributor indicates
    * computation is complete by setting [CompletionResult.isLast] to `true`.
    */
   CompletionResult computeSuggestions(CompletionRequest request);
 }
 
 /**
  * The information about a requested list of completions.
  *
  * Clients are not expected to subtype this class.
  */
 abstract class CompletionRequest {
   /**
+   * Return the results that were returned the last time the contributor was
+   * asked for results, or `null` if this is the first request for results at
+   * this location.
+   */
+  //CompletionResult get previousResults;

[Brian Wilkerson, 2015/04/30 04:01:22]

I'm confused by this. If you're proposing that we drop the method, then we
should remove it. If you just can't implement it yet, perhaps it would be better
to leave it in the interface and implement it to throw an exception.

[danrubel, 2015/04/30 05:03:11]

I'm not sure so I commented it out. As mentioned above, this is step 1 of 4 or
5, so I'll clean it up as part of this process.

+
+  /**
    * Return the analysis context in which the completion is being requested.
    */
   AnalysisContext get context;
 
   /**
    * The offset within the source at which the completion is being requested.
    */
   int get offset;
 
   /**
-   * Return the results that were returned the last time the contributor was
-   * asked for results, or `null` if this is the first request for results at
-   * this location.
+   * Return the resource provider associated with this request.
    */
-  CompletionResult get previousResults;
+  ResourceProvider get provider;

[Brian Wilkerson, 2015/04/30 04:01:22]

The name 'provider' is fairly generic. Perhaps 'resourceProvider' to be
consistent with AnalysisServer (which I think will also end up being public API
at some point)?

[danrubel, 2015/04/30 05:03:11]

Good point. Renamed.

 
   /**
    * Return the source in which the completion is being requested.
    */
   Source get source;
 }
 
 /**
  * The result of computing suggestions for code completion.
  *
@@ skipping 31 matching lines @@
    * the replacementOffset will be the offset of the beginning of the
    * identifier.
    */
   int get replacementOffset;
 
   /**
    * Return the list of suggestions being contributed by the contributor.
    */
   List<CompletionSuggestion> get suggestions;
 }