Use unitMember/classMember/parameter names instead of offsets in index.

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

Index: pkg/analysis_server/lib/src/services/index/index.dart
diff --git a/pkg/analysis_server/lib/src/services/index/index.dart b/pkg/analysis_server/lib/src/services/index/index.dart
index 7270ac241aec63b6d5f45d6e6bf2c269bff5fbdc..aa0663732fc6225d45e8868f8ce76f3edd5d6fba 100644
--- a/pkg/analysis_server/lib/src/services/index/index.dart
+++ b/pkg/analysis_server/lib/src/services/index/index.dart
@@ -341,24 +341,39 @@ class _PackageIndexRequester {
    * [element] is not referenced in the [index].
    */
   int findElementId(Element element) {
+    IndexElementInfo info = new IndexElementInfo(element);
+    element = info.element;
     // Find the id of the element's unit.
     int unitId = getUnitId(element);
     if (unitId == -1) {
       return -1;
     }
     // Prepare information about the element.
-    ElementInfo info = PackageIndexAssembler.newElementInfo(unitId, element);
-    // Find the first occurrence of an element with the same offset.
-    int elementId = _findFirstOccurrence(index.elementOffsets, info.offset);
+    int unitMemberId = getElementUnitMemberId(element);
+    if (unitMemberId == -1) {
+      return -1;
+    }
+    int classMemberId = getElementClassMemberId(element);
+    if (classMemberId == -1) {
+      return -1;
+    }
+    int parameterId = getElementParameterId(element);
+    if (parameterId == -1) {
+      return -1;
+    }
+    // Try to find the element id using classMemberId, parameterId, and kind.
+    int elementId =
+        _findFirstOccurrence(index.elementNameUnitMemberIds, unitMemberId);
     if (elementId == -1) {
       return -1;
     }
-    // Try to find the element id using offset, unit and kind.
     for (;
-        elementId < index.elementOffsets.length &&
-            index.elementOffsets[elementId] == info.offset;
+        elementId < index.elementNameUnitMemberIds.length &&
+            index.elementNameUnitMemberIds[elementId] == unitMemberId;
         elementId++) {
       if (index.elementUnits[elementId] == unitId &&
+          index.elementNameClassMemberIds[elementId] == classMemberId &&
+          index.elementNameParameterIds[elementId] == parameterId &&
           index.elementKinds[elementId] == info.kind) {
         return elementId;
       }
@@ -383,6 +398,45 @@ class _PackageIndexRequester {
   }
 
   /**
+   * Return the [element]'s class member name identifier, `null` is not a class
+   * member, or `-1` if the [element] is not referenced in the [index].
+   */
+  int getElementClassMemberId(Element element) {
+    for (; element != null; element = element.enclosingElement) {
+      if (element.enclosingElement is ClassElement) {
+        return getStringId(element.name);
+      }
+    }
+    return getStringId(PackageIndexAssembler.NULL_STRING);
+  }
+
+  /**
+   * Return the [element]'s class member name identifier, `null` is not a class
+   * member, or `-1` if the [element] is not referenced in the [index].
+   */
+  int getElementParameterId(Element element) {
+    for (; element != null; element = element.enclosingElement) {
+      if (element is ParameterElement) {
+        return getStringId(element.name);
+      }
+    }
+    return getStringId(PackageIndexAssembler.NULL_STRING);
+  }
+
+  /**
+   * Return the [element]'s top-level name identifier, `0` is the unit, or
+   * `-1` if the [element] is not referenced in the [index].
+   */
+  int getElementUnitMemberId(Element element) {
+    for (; element != null; element = element.enclosingElement) {
+      if (element.enclosingElement is CompilationUnitElement) {
+        return getStringId(element.name);
+      }
+    }
+    return getStringId(PackageIndexAssembler.NULL_STRING);
+  }
+
+  /**
    * Complete with a list of locations where the given [element] has relation
    * of the given [kind].
    */