Add the 'docRange' property and use it to compute documentation comment.

pkg/analyzer/lib/src/context/context.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 analyzer.src.context.context;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/instrumentation/instrumentation.dart';
 import 'package:analyzer/plugin/task.dart';
 import 'package:analyzer/src/cancelable_future.dart';
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/constant.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart'
     hide
         AnalysisCache,
         CachePartition,
         SdkCachePartition,
         UniversalCachePartition,
         WorkManager;
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/html.dart' as ht show HtmlUnit;
 import 'package:analyzer/src/generated/incremental_resolver.dart';
 import 'package:analyzer/src/generated/java_core.dart';
 import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/resolver.dart';
-import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/sdk.dart' show DartSdk;
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/utilities_collection.dart';
 import 'package:analyzer/src/task/dart.dart';
 import 'package:analyzer/src/task/dart_work_manager.dart';
 import 'package:analyzer/src/task/driver.dart';
 import 'package:analyzer/src/task/incremental_element_builder.dart';
 import 'package:analyzer/src/task/manager.dart';
 import 'package:analyzer/task/dart.dart';
 import 'package:analyzer/task/general.dart';
@@ skipping 524 matching lines @@
 
   @override
   String computeDocumentationComment(Element element) {
     if (element == null) {
       return null;
     }
     Source source = element.source;
     if (source == null) {
       return null;
     }
-    CompilationUnit unit = parseCompilationUnit(source);
-    if (unit == null) {
+    SourceRange docRange = element.docRange;
+    if (docRange == null) {
       return null;
     }
-    NodeLocator locator = new NodeLocator(element.nameOffset);
-    AstNode nameNode = locator.searchWithin(unit);
-    while (nameNode != null) {
-      if (nameNode is AnnotatedNode) {
-        Comment comment = nameNode.documentationComment;
-        if (comment == null) {
-          return null;
-        }
-        StringBuffer buffer = new StringBuffer();
-        List<Token> tokens = comment.tokens;
-        for (int i = 0; i < tokens.length; i++) {
-          if (i > 0) {
-            buffer.write("\n");
-          }
-          buffer.write(tokens[i].lexeme);
-        }
-        return buffer.toString();
-      }
-      nameNode = nameNode.parent;
-    }
-    return null;
+    String code = getContents(source).data;
+    String comment = code.substring(docRange.offset, docRange.end);
+    return comment.replaceAll('\r\n', '\n');
   }
 
   @override
   List<AnalysisError> computeErrors(Source source) {
     String name = source.shortName;
     if (AnalysisEngine.isDartFileName(name)) {
       return computeResult(source, DART_ERRORS);
     } else if (AnalysisEngine.isHtmlFileName(name)) {
       return computeResult(source, HTML_ERRORS);
     }
@@ skipping 1498 matching lines @@
         new PendingFuture<T>(_context, target, computeValue);
     if (!pendingFuture.evaluate(entry)) {
       _context._pendingFutureTargets
           .putIfAbsent(target, () => <PendingFuture>[])
           .add(pendingFuture);
       scheduleComputation();
     }
     return pendingFuture.future;
   }
 }