Make IndexableObjectKind parameterized.

LMK if this is a bad change.

R=brianwilkerson@google.com
BUG=

Review URL: https://codereview.chromium.org/1413563004 .

pkg/analysis_server/lib/plugin/index/index_core.dart

@@ -24,7 +24,7 @@ typedef int StringToInt(String string);
 /**
  * An object that can have a [Relationship] with various [Location]s in a code
  * base. The object is abstractly represented by a [kind] and an [offset] within
- * a [source].
+ * a file with the [filePath].
  *
  * Clients must ensure that two distinct objects in the same source cannot have
  * the same kind and offset. Failure to do so will make it impossible for
@@ -44,7 +44,7 @@ abstract class IndexableObject {
   IndexableObjectKind get kind;
 
   /**
-   * Return the offset of the indexable object within its source.
+   * Return the offset of the indexable object within its file.
    */
   int get offset;
 }
@@ -54,7 +54,7 @@ abstract class IndexableObject {
  *
  * Clients may implement this class when implementing plugins.
  */
-abstract class IndexableObjectKind {
+abstract class IndexableObjectKind<T extends IndexableObject> {
   /**
    * The next available index for a newly created kind of indexable object.
    */
@@ -84,7 +84,7 @@ abstract class IndexableObjectKind {
    * [context], in the source with the given [filePath], and at the given
    * [offset].
    */
-  IndexableObject decode(AnalysisContext context, String filePath, int offset);
+  T decode(AnalysisContext context, String filePath, int offset);
 
   /**
    * Returns the hash value that corresponds to the given [indexable].
@@ -105,7 +105,7 @@ abstract class IndexableObjectKind {
    * object does not have a name, some other value may be returned, but it still
    * must be always the same for the same object and have good selectivity.
    */
-  int encodeHash(StringToInt stringToInt, IndexableObject indexable);
+  int encodeHash(StringToInt stringToInt, T indexable);
 
   /**
    * Return the object kind with the given [index].

pkg/analysis_server/lib/src/services/index/index.dart

@@ -81,7 +81,7 @@ class IndexableName implements IndexableObject {
   String get filePath => null;
 
   @override
-  IndexableObjectKind get kind => IndexableNameKind.INSTANCE;
+  IndexableNameKind get kind => IndexableNameKind.INSTANCE;
 
   @override
   int get offset {
@@ -99,7 +99,7 @@ class IndexableName implements IndexableObject {
 /**
  * The kind of an indexable name.
  */
-class IndexableNameKind implements IndexableObjectKind {
+class IndexableNameKind implements IndexableObjectKind<IndexableName> {
   /**
    * The unique instance of this class.
    */
@@ -119,14 +119,14 @@ class IndexableNameKind implements IndexableObjectKind {
   }
 
   @override
-  IndexableObject decode(AnalysisContext context, String filePath, int offset) {
+  IndexableName decode(AnalysisContext context, String filePath, int offset) {
     throw new UnsupportedError(
         'Indexable names cannot be decoded through their kind');
   }
 
   @override
-  int encodeHash(StringToInt stringToInt, IndexableObject indexable) {
-    String name = (indexable as IndexableName).name;
+  int encodeHash(StringToInt stringToInt, IndexableName indexable) {
+    String name = indexable.name;
     return stringToInt(name);
   }
 }

pkg/analysis_server/lib/src/services/index/indexable_element.dart

@@ -30,11 +30,16 @@ class IndexableElement implements IndexableObject {
     }
   }
 
+  @override
+  String get filePath {
+    return element.source?.fullName;
+  }
+
   @override
   int get hashCode => element.hashCode;
 
   @override
-  IndexableObjectKind get kind => IndexableElementKind.forElement(element);
+  IndexableElementKind get kind => IndexableElementKind.forElement(element);
 
   @override
   int get offset {
@@ -44,11 +49,6 @@ class IndexableElement implements IndexableObject {
     return element.nameOffset;
   }
 
-  @override
-  String get filePath {
-    return element.source?.fullName;
-  }
-
   @override
   bool operator ==(Object object) =>
       object is IndexableElement && element == object.element;
@@ -60,7 +60,7 @@ class IndexableElement implements IndexableObject {
 /**
  * The kind associated with an [IndexableElement].
  */
-class IndexableElementKind implements IndexableObjectKind {
+class IndexableElementKind implements IndexableObjectKind<IndexableElement> {
   /**
    * A table mapping element kinds to the corresponding indexable element kind.
    */
@@ -104,7 +104,8 @@ class IndexableElementKind implements IndexableObjectKind {
   }
 
   @override
-  IndexableObject decode(AnalysisContext context, String filePath, int offset) {
+  IndexableElement decode(
+      AnalysisContext context, String filePath, int offset) {
     List<Source> unitSources = context.getSourcesWithFullName(filePath);
     for (Source unitSource in unitSources) {
       List<Source> libSources = context.getLibrariesContaining(unitSource);
@@ -143,17 +144,15 @@ class IndexableElementKind implements IndexableObjectKind {
   }
 
   @override
-  int encodeHash(StringToInt stringToInt, IndexableObject indexable) {
-    Element element = (indexable as IndexableElement).element;
+  int encodeHash(StringToInt stringToInt, IndexableElement indexable) {
+    Element element = indexable.element;
     String elementName = element.displayName;
     int elementNameId = stringToInt(elementName);
-    if (indexable is IndexableElement) {
-      LibraryElement libraryElement = indexable.element.library;
-      if (libraryElement != null) {
-        String libraryPath = libraryElement.source.fullName;
-        int libraryPathId = stringToInt(libraryPath);
-        return JenkinsSmiHash.combine(libraryPathId, elementNameId);
-      }
+    LibraryElement libraryElement = element.library;
+    if (libraryElement != null) {
+      String libraryPath = libraryElement.source.fullName;
+      int libraryPathId = stringToInt(libraryPath);
+      return JenkinsSmiHash.combine(libraryPathId, elementNameId);
     }
     return elementNameId;
   }

pkg/analysis_server/lib/src/services/index/indexable_file.dart

@@ -42,7 +42,7 @@ class IndexableFile implements IndexableObject {
 /**
  * The kind of an indexable file.
  */
-class IndexableFileKind implements IndexableObjectKind {
+class IndexableFileKind implements IndexableObjectKind<IndexableFile> {
   /**
    * The unique instance of this class.
    */
@@ -62,13 +62,13 @@ class IndexableFileKind implements IndexableObjectKind {
   }
 
   @override
-  IndexableObject decode(AnalysisContext context, String filePath, int offset) {
+  IndexableFile decode(AnalysisContext context, String filePath, int offset) {
     return new IndexableFile(filePath);
   }
 
   @override
-  int encodeHash(StringToInt stringToInt, IndexableObject indexable) {
-    String path = (indexable as IndexableFile).path;
+  int encodeHash(StringToInt stringToInt, IndexableFile indexable) {
+    String path = indexable.path;
     return stringToInt(path);
   }
 }