Use shorter DartElementLocation.

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

 // Copyright (c) 2014, 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 services.src.index.store.codec;
 
 import 'dart:collection';
 
 import 'package:analysis_server/src/services/index/index.dart';
 import 'package:analysis_server/src/services/index/store/collection.dart';
@@ skipping 50 matching lines @@
       _indexToContext.remove(id);
     }
   }
 }
 
 
 /**
  * A helper that encodes/decodes [Element]s to/from integers.
  */
 class ElementCodec {
+  static const KIND_DART = 0;
+  static const KIND_NAME = 1;
+  static const KIND_UNKNOWN = 2;
+
   final StringCodec _stringCodec;
+  final ElementKindCodec _kindCodec = new ElementKindCodec();
 
   /**
    * A table mapping element encodings to a single integer.
    */
   final IntArrayToIntMap _pathToIndex = new IntArrayToIntMap();
 
   /**
    * A list that works as a mapping of integers to element encodings.
    */
   final List<List<int>> _indexToPath = <List<int>>[];
 
   ElementCodec(this._stringCodec);
 
   /**
    * Returns an [Element] that corresponds to the given location.
    *
    * @param context the [AnalysisContext] to find [Element] in
    * @param index an integer corresponding to the [Element]
    * @return the [Element] or `null`
    */
   Element decode(AnalysisContext context, int index) {
     List<int> path = _indexToPath[index];
-    List<String> components = _getLocationComponents(path);
-    ElementLocation location = new ElementLocationImpl.con3(components);
-    Element element = context.getElement(location);
-    return element;
+    if (path[0] == KIND_DART) {
+      String librarySourceEncoding = _stringCodec.decode(path[1]);
+      String unitSourceEncoding = _stringCodec.decode(path[2]);
+      int nameOffset = path[3];
+      ElementKind kind = _kindCodec.decode(path[4]);
+      ElementLocation location = new DartElementLocation(
+          librarySourceEncoding,
+          unitSourceEncoding,
+          nameOffset,
+          kind);
+      return context.getElement(location);
+    }
+    // TODO(scheglov) support for KIND_HTML ?

[Brian Wilkerson, 2014/11/18 15:11:22]

And KIND_NAME.

+    return null;
   }
 
   /**
    * Returns a unique integer that corresponds to the given [Element].
    *
    * If [forKey] is `true` then [element] is a part of a key, so it should use
    * file paths instead of [Element] location URIs.
    */
   int encode(Element element, bool forKey) {
     List<int> path = _getLocationPath(element, forKey);
@@ skipping 13 matching lines @@
     List<int> path = _getLocationPathLimited(element);
     int index = _pathToIndex[path];
     if (index == null) {
       index = _indexToPath.length;
       _pathToIndex[path] = index;
       _indexToPath.add(path);
     }
     return index;
   }
 
-  List<String> _getLocationComponents(List<int> path) {
-    int length = path.length;
-    List<String> components = new List<String>();
-    for (int i = 0; i < length; i++) {
-      int componentId = path[i];
-      String component = _stringCodec.decode(componentId);
-      if (i < length - 1 && path[i + 1] < 0) {
-        component += '@${(-path[i + 1])}';
-        i++;
-      }
-      components.add(component);
-    }
-    return components;
-  }
-
   /**
    * If [usePath] is `true` then [Source] path should be used instead of URI.
    */
   List<int> _getLocationPath(Element element, bool usePath) {
-    // prepare the location components
-    List<String> components = element.location.components;
-    if (usePath) {
-      LibraryElement library = element.library;
-      if (library != null) {
-        components[0] = library.source.fullName;
-        if (element.enclosingElement is CompilationUnitElement) {
-          components[1] = library.definingCompilationUnit.source.fullName;
-        }
+    LibraryElement library = element.library;
+    // DynamicElement, NameElement
+    if (library == null) {
+      int nameId = _stringCodec.encode(element.name);
+      return <int>[KIND_NAME, nameId];
+    }
+    // normal Element
+    ElementLocation location = element.location;
+    if (location is DartElementLocation) {
+      String librarySourceEncoding;
+      String unitSourceEncoding;
+      if (usePath) {
+        unitSourceEncoding = library.source.fullName;
+        unitSourceEncoding = element.source.fullName;
+      } else {
+        librarySourceEncoding = location.librarySourceEncoding;
+        unitSourceEncoding = location.unitSourceEncoding;
       }
+      int libraryId = _stringCodec.encode(librarySourceEncoding);
+      int unitId = _stringCodec.encode(unitSourceEncoding);
+      // done
+      int nameOffset = location.nameOffset;

[Brian Wilkerson, 2014/11/18 15:11:22]

Do we need to ensure that the name offset is non-negative, or do we produce a
unique offset for every kind of element?

+      int kindId = _kindCodec.encode(location.kind);
+      return <int>[KIND_DART, libraryId, unitId, nameOffset, kindId];
     }
-    // encode the location
-    int length = components.length;
-    if (_hasLocalOffset(components)) {
-      List<int> path = new List<int>();
-      for (String component in components) {
-        int atOffset = component.indexOf('@');
-        if (atOffset == -1) {
-          path.add(_stringCodec.encode(component));
-        } else {
-          String preAtString = component.substring(0, atOffset);
-          String atString = component.substring(atOffset + 1);
-          path.add(_stringCodec.encode(preAtString));
-          path.add(-1 * int.parse(atString));
-        }
-      }
-      return path;
-    } else {
-      List<int> path = new List<int>.filled(length, 0);
-      for (int i = 0; i < length; i++) {
-        String component = components[i];
-        path[i] = _stringCodec.encode(component);
-      }
-      return path;
-    }
+    // unknown
+    return <int>[KIND_UNKNOWN];
   }
 
   /**
    * Returns an approximation of the [element]'s location.
    */
   List<int> _getLocationPathLimited(Element element) {
     String firstComponent;
     {
       LibraryElement libraryElement = element.library;
       if (libraryElement != null) {
         firstComponent = libraryElement.source.fullName;
       } else {
         firstComponent = 'null';
       }
     }
     String lastComponent = element.displayName;
     int firstId = _stringCodec.encode(firstComponent);
     int lastId = _stringCodec.encode(lastComponent);
     return <int>[firstId, lastId];
   }
+}
 
-  static bool _hasLocalOffset(List<String> components) {
-    for (String component in components) {
-      if (component.indexOf('@') != -1) {
-        return true;
+
+/**
+ * A helper that encodes/decodes [ElementKind]s to/from integers.
+ */
+class ElementKindCodec {
+  ElementKind decode(int id) {
+    for (ElementKind kind in ElementKind.values) {
+      if (kind.ordinal == id) {
+        return kind;
       }
     }
-    return false;
+    return null;
+  }
+
+  int encode(ElementKind kind) {
+    return kind.ordinal;
   }
 }
 
 
 /**
  * A helper that encodes/decodes [Relationship]s to/from integers.
  */
 class RelationshipCodec {
   final StringCodec _stringCodec;
 
@@ skipping 36 matching lines @@
   int encode(String name) {
     int index = nameToIndex[name];
     if (index == null) {
       index = _indexToName.length;
       nameToIndex[name] = index;
       _indexToName.add(name);
     }
     return index;
   }
 }