incremental progress reworking code completion manager / computers

pkg/analysis_services/lib/completion/completion_computer.dart

Index: pkg/analysis_services/lib/completion/completion_computer.dart
diff --git a/pkg/analysis_services/lib/completion/completion_computer.dart b/pkg/analysis_services/lib/completion/completion_computer.dart
index 5158f0fac1709dfaa4c8dc31ce11a6a3b6a0e887..b4517b8f47421862f81869dc4c7a108a0eca2ad7 100644
--- a/pkg/analysis_services/lib/completion/completion_computer.dart
+++ b/pkg/analysis_services/lib/completion/completion_computer.dart
@@ -29,11 +29,47 @@ abstract class CompletionComputer {
 abstract class CompletionManager {
 
   /**
+   * Create a manager for the given request.
+   */
+  static CompletionManager create(Source source, int offset,
+      SearchEngine searchEngine) {
+    if (AnalysisEngine.isDartFileName(source.shortName)) {
+      return new DartCompletionManager(source, offset, searchEngine);
+    }
+    return new NoOpCompletionManager(source, offset);
+  }
+
+  StreamController<CompletionResult> controller;
+
+  /**
+   * Generate a stream of code completion results.
+   */
+  Stream<CompletionResult> results() {
+    controller = new StreamController<CompletionResult>(onListen: () {
+      scheduleMicrotask(compute);
+    });
+    return controller.stream;
+  }
+
+  /**
+   * Compute completion results 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].
+   */
+  void compute();
+}
+
+/**
+ * Code completion result generated by an [CompletionManager].
+ */
+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).
    */
-  int get replacementLength;
+  final int replacementLength;
 
   /**
    * The offset of the start of the text to be replaced. This will be different
@@ -41,23 +77,21 @@ abstract class CompletionManager {
    * portion of an identifier before the original offset. In particular, the
    * replacementOffset will be the offset of the beginning of said identifier.
    */
-  int get replacementOffset;
+  final int replacementOffset;
 
   /**
-   * Generate code completion computers for the given situation.
+   * The suggested completions.
    */
-  Future<List<CompletionComputer>> generate();
+  final List<CompletionSuggestion> suggestions;
 
   /**
-   * Create a manager for the given request.
+   * `true` if this is that last set of results that will be returned
+   * for the indicated completion.
    */
-  static CompletionManager create(Source source, int offset,
-      SearchEngine searchEngine) {
-    if (AnalysisEngine.isDartFileName(source.shortName)) {
-      return new DartCompletionManager(source, offset, searchEngine);
-    }
-    return new NoOpCompletionManager(source, offset);
-  }
+  final bool last;
+
+  CompletionResult(this.replacementOffset, this.replacementLength,
+      this.suggestions, this.last);
 }
 
 /**
@@ -71,23 +105,11 @@ class DartCompletionManager extends CompletionManager {
   DartCompletionManager(this.source, this.offset, this.searchEngine);
 
   @override
-  int get replacementLength => 0;
-
-  @override
-  int get replacementOffset => offset;
-
-  @override
-  Future<List<CompletionComputer>> generate() {
-    List<CompletionComputer> computers = [];
-    computers.add(new TopLevelComputer(searchEngine));
-    return new Future.value(computers);
-  }
-}
-
-class NoOpCompletionComputer extends CompletionComputer {
-  @override
-  Future<List<CompletionSuggestion>> compute() {
-    return new Future.value([]);
+  void compute() {
+    var computer = new TopLevelComputer(searchEngine);
+    computer.compute().then((List<CompletionSuggestion> suggestions) {
+      controller.add(new CompletionResult(offset, 0, suggestions, true));
+    });
   }
 }
 
@@ -98,13 +120,7 @@ class NoOpCompletionManager extends CompletionManager {
   NoOpCompletionManager(this.source, this.offset);
 
   @override
-  int get replacementLength => 0;
-
-  @override
-  int get replacementOffset => offset;
-
-  @override
-  Future<List<CompletionComputer>> generate() {
-    return new Future.value([new NoOpCompletionComputer()]);
+  void compute() {
+    controller.add(new CompletionResult(offset, 0, [], true));
   }
 }