Generalize DartSdkManager to support embedder SDKs

pkg/analyzer/lib/src/generated/sdk.dart

Index: pkg/analyzer/lib/src/generated/sdk.dart
diff --git a/pkg/analyzer/lib/src/generated/sdk.dart b/pkg/analyzer/lib/src/generated/sdk.dart
index 8705867323fc27716d9745ec22ba2d6b5f7df1e4..16bc5e85d125ff8b6fc6f281eb6295777683c1ff 100644
--- a/pkg/analyzer/lib/src/generated/sdk.dart
+++ b/pkg/analyzer/lib/src/generated/sdk.dart
@@ -11,6 +11,7 @@ import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, AnalysisOptions;
 import 'package:analyzer/src/generated/source.dart' show Source;
+import 'package:analyzer/src/generated/utilities_general.dart';
 
 /**
  * A function used to create a new DartSdk with the given [options]. If the
@@ -96,20 +97,32 @@ abstract class DartSdk {
  */
 class DartSdkManager {
   /**
+   * The absolute path to the directory containing the default SDK.
+   */
+  final String defaultSdkDirectory;
+
+  /**
+   * A flag indicating whether it is acceptable to use summaries when they are
+   * available.
+   */
+  final bool canUseSummaries;
+
+  /**
    * The function used to create new SDK's.
    */
   final SdkCreator sdkCreator;
 
   /**
-   * A table mapping (an encoding of) analysis options to the SDK that has been
-   * configured with those options.
+   * A table mapping (an encoding of) analysis options and SDK locations to the
+   * DartSdk from that location that has been configured with those options.
    */
-  Map<int, DartSdk> sdkMap = new HashMap<int, DartSdk>();
+  Map<SdkDescription, DartSdk> sdkMap = new HashMap<SdkDescription, DartSdk>();
 
   /**
    * Initialize a newly created manager.
    */
-  DartSdkManager(this.sdkCreator);
+  DartSdkManager(
+      this.defaultSdkDirectory, this.canUseSummaries, this.sdkCreator);
 
   /**
    * Return any SDK that has been created, or `null` if no SDKs have been
@@ -127,9 +140,20 @@ class DartSdkManager {
    * If such an SDK has not yet been created, then the [sdkCreator] will be
    * invoked to create it.
    */
+  DartSdk getSdk(SdkDescription description, DartSdk ifAbsent()) {
+    return sdkMap.putIfAbsent(description, ifAbsent);
+  }
+
+  /**
+   * Return the Dart SDK that is appropriate for the given analysis [options].
+   * If such an SDK has not yet been created, then the [sdkCreator] will be
+   * invoked to create it.
+   */
   DartSdk getSdkForOptions(AnalysisOptions options) {
-    int encoding = options.encodeCrossContextOptions();
-    return sdkMap.putIfAbsent(encoding, () => sdkCreator(options));
+    // TODO(brianwilkerson) Remove this method and the field sdkCreator.
+    SdkDescription description =
+        new SdkDescription(<String>[defaultSdkDirectory], options);
+    return getSdk(description, () => sdkCreator(options));
   }
 }
 
@@ -173,6 +197,58 @@ class LibraryMap {
   int size() => _libraryMap.length;
 }
 
+/**
+ * A description of a [DartSdk].
+ */
+class SdkDescription {
+  /**
+   * The paths to the files or directories that define the SDK.
+   */
+  final List<String> paths;
+
+  /**
+   * The analysis options that will be used by the SDK's context.
+   */
+  final AnalysisOptions options;
+
+  /**
+   * Initialize a newly created SDK description to describe an SDK based on the
+   * files or directories at the given [paths] that is analyzed using the given
+   * [options].
+   */
+  SdkDescription(this.paths, this.options);
+
+  @override
+  int get hashCode {
+    int hashCode = options.encodeCrossContextOptions();
+    for (String path in paths) {
+      hashCode = JenkinsSmiHash.combine(hashCode, path.hashCode);
+    }
+    return JenkinsSmiHash.finish(hashCode);
+  }
+
+  @override
+  bool operator ==(Object other) {
+    if (other is SdkDescription) {
+      if (options.encodeCrossContextOptions() !=
+          other.options.encodeCrossContextOptions()) {
+        return false;
+      }
+      int length = paths.length;
+      if (other.paths.length != length) {
+        return false;
+      }
+      for (int i = 0; i < length; i++) {
+        if (other.paths[i] != paths[i]) {
+          return false;
+        }
+      }
+      return true;
+    }
+    return false;
+  }
+}
+
 class SdkLibrariesReader_LibraryBuilder extends RecursiveAstVisitor<Object> {
   /**
    * The prefix added to the name of a library to form the URI used in code to