Move LibraryUnitTarget into API.

pkg/analyzer/lib/task/dart.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.task.dart;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer/src/generated/utilities_general.dart';
 import 'package:analyzer/task/model.dart';
 
 /**
  * The analysis errors associated with a target.
  *
  * The value combines errors represented by multiple other results.
  */
 // TODO(brianwilkerson) If we want to associate errors with targets smaller than
 // a file, we will need other contribution points to collect them. In which case
 // we might want to rename this and/or document that it applies to files.
@@ skipping 91 matching lines @@
 /**
  * The sources of the Dart files that a library consists of.
  *
  * The list will include the source of the defining unit and [INCLUDED_PARTS].
  * So, it is never empty or `null`.
  *
  * The result is only available for targets representing a Dart library.
  */
 final ListResultDescriptor<Source> UNITS =
     new ListResultDescriptor<Source>('UNITS', Source.EMPTY_ARRAY);
+
+/**
+ * A specific compilation unit in a specific library.
+ *
+ * This kind of target is associated with information about a compilation unit
+ * that differs based on the library that the unit is a part of. For example,
+ * the result of resolving a compilation unit depends on the imports, which can
+ * change if a single part is included in more than one library.
+ */
+class LibrarySpecificUnit implements AnalysisTarget {
+  /**
+   * The defining compilation unit of the library in which the [unit]
+   * is analyzed.
+   */
+  final Source library;
+
+  /**
+   * The compilation unit which belongs to the [library].
+   */
+  final Source unit;
+
+  /**
+   * Initialize a newly created target for the [unit] in the [library].
+   */
+  LibrarySpecificUnit(this.library, this.unit);
+
+  @override
+  int get hashCode {
+    return JenkinsSmiHash.combine(library.hashCode, unit.hashCode);
+  }
+
+  @override
+  Source get source => unit;
+
+  @override
+  bool operator ==(other) {
+    return other is LibrarySpecificUnit &&
+        other.library == library &&
+        other.unit == unit;
+  }
+}