Sort strings in the index.

R=brianwilkerson@google.com
BUG=

Review URL: https://codereview.chromium.org/1774253002 .

pkg/analyzer/lib/src/summary/format.dart

@@ -1677,7 +1677,9 @@ class PackageIndexBuilder extends Object with _PackageIndexMixin implements idl.
   List<String> get strings => _strings ??= <String>[];
 
   /**
-   * List of unique element strings used in this [PackageIndex].
+   * List of unique element strings used in this [PackageIndex].  The list is
+   * sorted in ascending order, so that the client can quickly check the
+   * presence of a string in this [PackageIndex].
    */
   void set strings(List<String> _value) {
     assert(!_finished);

pkg/analyzer/lib/src/summary/format.fbs

@@ -891,7 +891,9 @@ table PackageIndex {
   elementUnits:[uint] (id: 0);
 
   /**
-   * List of unique element strings used in this [PackageIndex].
+   * List of unique element strings used in this [PackageIndex].  The list is
+   * sorted in ascending order, so that the client can quickly check the
+   * presence of a string in this [PackageIndex].
    */
   strings:[string] (id: 6);
 

pkg/analyzer/lib/src/summary/idl.dart

@@ -566,7 +566,9 @@ abstract class PackageIndex extends base.SummaryClass {
   List<int> get elementUnits;
 
   /**
-   * List of unique element strings used in this [PackageIndex].
+   * List of unique element strings used in this [PackageIndex].  The list is
+   * sorted in ascending order, so that the client can quickly check the
+   * presence of a string in this [PackageIndex].
    */
   @Id(6)
   List<String> get strings;

pkg/analyzer/lib/src/summary/index_unit.dart

@@ -33,26 +33,20 @@ class PackageIndexAssembler {
 
   /**
    * Each item of this list corresponds to the library URI of a unique
-   * [CompilationUnitElement].  It is an index into [_strings].
+   * [CompilationUnitElement].
    */
-  final List<int> _unitLibraryUris = <int>[];
+  final List<_StringInfo> _unitLibraryUris = <_StringInfo>[];
 
   /**
    * Each item of this list corresponds to the unit URI of a unique
-   * [CompilationUnitElement].  It is an index into [_strings].
+   * [CompilationUnitElement].
    */
-  final List<int> _unitUnitUris = <int>[];
+  final List<_StringInfo> _unitUnitUris = <_StringInfo>[];
 
   /**
-   * Map associating strings with their identifiers, which are indices
-   * into [_strings].
+   * Map associating strings with their [_StringInfo]s.
    */
-  final Map<String, int> _stringMap = <String, int>{};
-
-  /**
-   * List of unique strings used in this index.
-   */
-  final List<String> _strings = <String>[];
+  final Map<String, _StringInfo> _stringMap = <String, _StringInfo>{};
 
   /**
    * List of information about each unit indexed in this index.
@@ -64,6 +58,15 @@ class PackageIndexAssembler {
    * [index].
    */
   PackageIndexBuilder assemble() {
+    // sort strings end set IDs
+    List<_StringInfo> stringInfoList = _stringMap.values.toList();
+    stringInfoList.sort((a, b) {
+      return a.value.compareTo(b.value);
+    });
+    for (int i = 0; i < stringInfoList.length; i++) {
+      stringInfoList[i].id = i;
+    }
+    // sort elements and set IDs
     List<_ElementInfo> elementInfoList = _elementMap.values.toList();
     elementInfoList.sort((a, b) {
       return a.offset - b.offset;
@@ -72,12 +75,12 @@ class PackageIndexAssembler {
       elementInfoList[i].id = i;
     }
     return new PackageIndexBuilder(
-        unitLibraryUris: _unitLibraryUris,
-        unitUnitUris: _unitUnitUris,
+        unitLibraryUris: _unitLibraryUris.map((s) => s.id).toList(),
+        unitUnitUris: _unitUnitUris.map((s) => s.id).toList(),
         elementUnits: elementInfoList.map((e) => e.unitId).toList(),
         elementOffsets: elementInfoList.map((e) => e.offset).toList(),
         elementKinds: elementInfoList.map((e) => e.kind).toList(),
-        strings: _strings,
+        strings: stringInfoList.map((s) => s.value).toList(),
         units: _units.map((unit) => unit.assemble()).toList());
   }
 
@@ -112,14 +115,12 @@ class PackageIndexAssembler {
   }
 
   /**
-   * Add information about [str] to [_strings] if necessary, and return the
-   * location in this array representing [str].
+   * Return the unique [_StringInfo] corresponding the [str].  The field
+   * [_StringInfo.id] is filled by [assemble] during final sorting.
    */
-  int _getStringId(String str) {
+  _StringInfo _getStringInfo(String str) {
     return _stringMap.putIfAbsent(str, () {
-      int id = _strings.length;
-      _strings.add(str);
-      return id;
+      return new _StringInfo(str);
     });
   }
 
@@ -132,18 +133,19 @@ class PackageIndexAssembler {
     return _unitMap.putIfAbsent(unitElement, () {
       assert(_unitLibraryUris.length == _unitUnitUris.length);
       int id = _unitUnitUris.length;
-      _unitLibraryUris.add(_getUriId(unitElement.library.source.uri));
-      _unitUnitUris.add(_getUriId(unitElement.source.uri));
+      _unitLibraryUris.add(_getUriInfo(unitElement.library.source.uri));
+      _unitUnitUris.add(_getUriInfo(unitElement.source.uri));
       return id;
     });
   }
 
   /**
-   * Return the identifier corresponding to [uri].
+   * Return the unique [_StringInfo] corresponding [uri].  The field
+   * [_StringInfo.id] is filled by [assemble] during final sorting.
    */
-  int _getUriId(Uri uri) {
+  _StringInfo _getUriInfo(Uri uri) {
     String str = uri.toString();
-    return _getStringId(str);
+    return _getStringInfo(str);
   }
 
   /**
@@ -187,9 +189,10 @@ class PackageIndexAssembler {
  */
 class _DefinedNameInfo {
   /**
-   * The identifier of the name returned [PackageIndexAssembler._getStringId].
+   * The information about the name returned from
+   * [PackageIndexAssembler._getStringInfo].
    */
-  final int nameId;
+  final _StringInfo nameInfo;
 
   /**
    * The coarse-grained kind of the defined name.
@@ -201,7 +204,7 @@ class _DefinedNameInfo {
    */
   final int offset;
 
-  _DefinedNameInfo(this.nameId, this.kind, this.offset);
+  _DefinedNameInfo(this.nameInfo, this.kind, this.offset);
 }
 
 /**
@@ -232,6 +235,24 @@ class _ElementInfo {
   _ElementInfo(this.unitId, this.offset, this.kind);
 }
 
+/**
+ * Information about a string referenced in the index.
+ */
+class _StringInfo {
+  /**
+   * The value of the string.
+   */
+  final String value;
+
+  /**
+   * The unique id of the string.  It is set after indexing of the whole
+   * package is done and we are assembling the full package index.
+   */
+  int id;
+
+  _StringInfo(this.value);
+}
+
 /**
  * Information about a single relation.  Any [_ElementRelationInfo] is always
  * part of a [_UnitIndexAssembler], so [offset] and [length] should be
@@ -649,13 +670,14 @@ class _IndexContributor extends GeneralizingAstVisitor {
  */
 class _NameRelationInfo {
   /**
-   * The identifier of the name returned [PackageIndexAssembler._getStringId].
+   * The information about the name returned from
+   * [PackageIndexAssembler._getStringInfo].
    */
-  final int nameId;
+  final _StringInfo nameInfo;
   final IndexRelationKind kind;
   final int offset;
 
-  _NameRelationInfo(this.nameId, this.kind, this.offset);
+  _NameRelationInfo(this.nameInfo, this.kind, this.offset);
 }
 
 /**
@@ -689,7 +711,7 @@ class _UnitIndexAssembler {
   }
 
   void addNameRelation(String name, IndexRelationKind kind, int offset) {
-    int nameId = pkg._getStringId(name);
+    _StringInfo nameId = pkg._getStringInfo(name);
     nameRelations.add(new _NameRelationInfo(nameId, kind, offset));
   }
 
@@ -699,17 +721,17 @@ class _UnitIndexAssembler {
    */
   UnitIndexBuilder assemble() {
     definedNames.sort((a, b) {
-      return a.nameId - b.nameId;
+      return a.nameInfo.id - b.nameInfo.id;
     });
     elementRelations.sort((a, b) {
       return a.elementInfo.id - b.elementInfo.id;
     });
     nameRelations.sort((a, b) {
-      return a.nameId - b.nameId;
+      return a.nameInfo.id - b.nameInfo.id;
     });
     return new UnitIndexBuilder(
         unit: unitId,
-        definedNames: definedNames.map((n) => n.nameId).toList(),
+        definedNames: definedNames.map((n) => n.nameInfo.id).toList(),
         definedNameKinds: definedNames.map((n) => n.kind).toList(),
         definedNameOffsets: definedNames.map((n) => n.offset).toList(),
         usedElements: elementRelations.map((r) => r.elementInfo.id).toList(),
@@ -718,13 +740,13 @@ class _UnitIndexAssembler {
         usedElementLengths: elementRelations.map((r) => r.length).toList(),
         usedElementIsQualifiedFlags:
             elementRelations.map((r) => r.isQualified).toList(),
-        usedNames: nameRelations.map((r) => r.nameId).toList(),
+        usedNames: nameRelations.map((r) => r.nameInfo.id).toList(),
         usedNameKinds: nameRelations.map((r) => r.kind).toList(),
         usedNameOffsets: nameRelations.map((r) => r.offset).toList());
   }
 
   void defineName(String name, IndexNameKind kind, int offset) {
-    int nameId = pkg._getStringId(name);
-    definedNames.add(new _DefinedNameInfo(nameId, kind, offset));
+    _StringInfo nameInfo = pkg._getStringInfo(name);
+    definedNames.add(new _DefinedNameInfo(nameInfo, kind, offset));
   }
 }