Adding package:code_transformers for unifying common transformers code

pkg/code_transformers/lib/src/resolver.dart

Index: pkg/code_transformers/lib/src/resolver.dart
diff --git a/pkg/code_transformers/lib/src/resolver.dart b/pkg/code_transformers/lib/src/resolver.dart
new file mode 100644
index 0000000000000000000000000000000000000000..80e385fd4e39db879a03e49a6b13f858735c41af
--- /dev/null
+++ b/pkg/code_transformers/lib/src/resolver.dart
@@ -0,0 +1,81 @@
+// 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 code_transformer.src.resolver;
+
+import 'package:analyzer/src/generated/element.dart';
+import 'package:barback/barback.dart';
+import 'package:source_maps/refactor.dart';
+import 'package:source_maps/span.dart' show SourceFile, Span;
+
+
+/// Class for working with a barback based resolved AST.
+abstract class Resolver {
+  /// The Dart entry point file where parsing begins.
+  AssetId get entryPoint;
+
+  /// Gets the resolved Dart library for the entry asset, or null if
+  /// the AST has not been resolved.
+  ///
+  /// If the AST has not been resolved then this normally means that the
+  /// transformer hosting this needs to be in an earlier phase.
+  LibraryElement get entryLibrary;
+
+  /// Gets all libraries accessible from the entry point, recursively.
+  ///
+  /// This includes all Dart SDK libraries as well.
+  Iterable<LibraryElement> get libraries;
+
+  /// Finds the first library identified by [libraryName], or null if no
+  /// library can be found.
+  LibraryElement getLibraryByName(String libraryName);
+
+  /// Finds the first library identified by [libraryName], or null if no
+  /// library can be found.
+  ///
+  /// [uri] must be an absolute URI of the form
+  /// `[dart:|package:]path/file.dart`.
+  LibraryElement getLibraryByUri(Uri uri);
+
+  /// Resolves a fully-qualified type name (library_name.ClassName).
+  ///
+  /// This will resolve the first instance of [typeName], because of potential
+  /// library name conflicts the name is not guaranteed to be unique.
+  ClassElement getType(String typeName);
+
+  /// Resolves a fully-qualified top-level library variable
+  /// (library_name.variableName).
+  ///
+  /// This will resolve the first instance of [variableName], because of
+  /// potential library name conflicts the name is not guaranteed to be unique.
+  Element getLibraryVariable(String variableName);
+
+  /// Resolves a fully-qualified top-level library function
+  /// (library_name.functionName).
+  ///
+  /// This will resolve the first instance of [functionName], because of
+  /// potential library name conflicts the name is not guaranteed to be unique.
+  Element getLibraryFunction(String functionName);
+
+  /// Gets an URI appropriate for importing the specified library.
+  ///
+  /// Returns null if the library cannot be imported via an absolute URI or
+  /// from [from] (if provided).
+  Uri getImportUri(LibraryElement lib, {AssetId from});
+
+  /// Get the asset ID of the file containing the asset.
+  AssetId getSourceAssetId(Element element);
+
+  /// Get the source span where the specified element was defined or null if
+  /// the element came from the Dart SDK.
+  Span getSourceSpan(Element element);
+
+  /// Creates a text edit transaction for the given element if it is able
+  /// to be edited, returns null otherwise.
+  ///
+  /// The transaction contains the entire text of the source file where the
+  /// element originated. If the element was from a library part then the
+  /// source file is the part file rather than the library.
+  TextEditTransaction createTextEditTransaction(Element element);
+}