Make LibraryIndex lazy.

pkg/kernel/lib/library_index.dart

 // Copyright (c) 2016, 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 kernel.library_index;
 
 import 'ast.dart';
 
 /// Provides name-based access to library, class, and member AST nodes.
 ///
 /// When constructed, a given set of libraries are indexed immediately, and
 /// will not be up-to-date with changes made after it was created.
 class LibraryIndex {
   static const String getterPrefix = 'get:';
   static const String setterPrefix = 'set:';
 
   /// A special class name that can be used to access the top-level members
   /// of a library.
   static const String topLevel = '::';
 
   final Map<String, _ClassTable> _libraries = <String, _ClassTable>{};
 
   /// Indexes the libraries with the URIs given in [libraryUris].
   LibraryIndex(Program program, Iterable<String> libraryUris) {
-    for (var uri in libraryUris) {
-      _libraries[uri] = new _ClassTable();
-    }
+    var libraryUriSet = libraryUris.toSet();
     for (var library in program.libraries) {
-      var index = _libraries['${library.importUri}'];
-      if (index != null) {
-        index.build(library);
+      var uri = '${library.importUri}';
+      if (libraryUriSet.contains(uri)) {
+        _libraries[uri] = new _ClassTable(library);
       }
     }
   }
 
   /// Indexes the libraries with the URIs given in [libraryUris].
   LibraryIndex.byUri(Program program, Iterable<Uri> libraryUris)
       : this(program, libraryUris.map((uri) => '$uri'));
 
-  /// Indexes the libraries with the URIs given in [libraryUris].
+  /// Indexes `dart:` libraries.
   LibraryIndex.coreLibraries(Program program) {
     for (var library in program.libraries) {
       if (library.importUri.scheme == 'dart') {
-        _libraries['${library.importUri}'] = new _ClassTable()..build(library);
+        _libraries['${library.importUri}'] = new _ClassTable(library);
       }
     }
   }
 
   /// Indexes the entire program.
   ///
   /// Consider using another constructor to only index the libraries that
   /// are needed.
   LibraryIndex.all(Program program) {
     for (var library in program.libraries) {
-      _libraries['${library.importUri}'] = new _ClassTable()..build(library);
+      _libraries['${library.importUri}'] = new _ClassTable(library);
     }
   }
 
   _ClassTable _getLibraryIndex(String uri) {
     _ClassTable libraryIndex = _libraries[uri];
     if (libraryIndex == null) {
       throw "The library '$uri' has not been indexed";
     }
     return libraryIndex;
   }
@@ skipping 58 matching lines @@
   }
 
   /// Like [getTopLevelMember] but returns `null` if not found.
   Member tryGetTopLevelMember(
       String library, String className, String memberName) {
     return tryGetMember(library, topLevel, memberName);
   }
 }
 
 class _ClassTable {
-  Library library;
-  final Map<String, _MemberTable> classes = <String, _MemberTable>{};
+  final Library library;
 
-  void build(Library library) {
-    this.library = library;
-    classes[LibraryIndex.topLevel] = new _MemberTable.topLevel(this);
-    for (var class_ in library.classes) {
-      classes[class_.name] = new _MemberTable(this, class_);
+  Map<String, _MemberTable> _classes;
+
+  _ClassTable(this.library);
+
+  Map<String, _MemberTable> get classes {
+    if (_classes == null) {
+      _classes = <String, _MemberTable>{};
+      _classes[LibraryIndex.topLevel] = new _MemberTable.topLevel(this);
+      for (var class_ in library.classes) {
+        _classes[class_.name] = new _MemberTable(this, class_);
+      }
     }
+    return _classes;
   }
 
   String get containerName {
     // For useful error messages, it can be helpful to indicate if the library
     // is external.  If a class or member was not found in an external library,
     // it might be that it exists in the actual library, but its interface was
     // not included in this build unit.
     return library.isExternal
         ? "external library '${library.importUri}'"
         : "library '${library.importUri}'";
@@ skipping 20 matching lines @@
   }
 
   Member tryGetMember(String className, String memberName) {
     return classes[className]?.tryGetMember(memberName);
   }
 }
 
 class _MemberTable {
   final _ClassTable parent;
   final Class class_; // Null for top-level.
-  final Map<String, Member> members = <String, Member>{};
+  Map<String, Member> _members;
 
   Library get library => parent.library;
 
-  _MemberTable(this.parent, this.class_) {
-    class_.procedures.forEach(addMember);
-    class_.fields.forEach(addMember);
-    class_.constructors.forEach(addMember);
-  }
+  _MemberTable(this.parent, this.class_);
 
-  _MemberTable.topLevel(this.parent) : class_ = null {
-    library.procedures.forEach(addMember);
-    library.fields.forEach(addMember);
+  _MemberTable.topLevel(this.parent) : class_ = null;
+
+  Map<String, Member> get members {
+    if (_members == null) {
+      _members = <String, Member>{};
+      if (class_ != null) {
+        class_.procedures.forEach(addMember);
+        class_.fields.forEach(addMember);
+        class_.constructors.forEach(addMember);
+      } else {
+        library.procedures.forEach(addMember);
+        library.fields.forEach(addMember);
+      }
+    }
+    return _members;
   }
 
   String getDisambiguatedName(Member member) {
     if (member is Procedure) {
       if (member.isGetter) return LibraryIndex.getterPrefix + member.name.name;
       if (member.isSetter) return LibraryIndex.setterPrefix + member.name.name;
     }
     return member.name.name;
   }
 
   void addMember(Member member) {
     if (member.name.isPrivate && member.name.library != library) {
       // Members whose name is private to other libraries cannot currently
       // be found with the LibraryIndex class.
       return;
     }
-    members[getDisambiguatedName(member)] = member;
+    _members[getDisambiguatedName(member)] = member;
   }
 
   String get containerName {
     if (class_ == null) {
       return "top-level of ${parent.containerName}";
     } else {
       return "class '${class_.name}' in ${parent.containerName}";
     }
   }
 
   Member getMember(String name) {
     var member = members[name];
     if (member == null) {
       String message = "A member with disambiguated name '$name' was not found "
           "in $containerName";
       var getter = LibraryIndex.getterPrefix + name;
       var setter = LibraryIndex.setterPrefix + name;
       if (members[getter] != null || members[setter] != null) {
         throw "$message. Did you mean '$getter' or '$setter'?";
       }
       throw message;
     }
     return member;
   }
 
   Member tryGetMember(String name) => members[name];
 }