Issue 27044. Summarize configurations of imports and exports, AST based.

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

 // Copyright (c) 2015, 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 analyzer.src.summary.public_namespace_visitor;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/summary/format.dart';
 import 'package:analyzer/src/summary/idl.dart';
 
 /**
  * Compute the public namespace portion of the summary for the given [unit],
  * which is presumed to be an unresolved AST.
  */
 UnlinkedPublicNamespaceBuilder computePublicNamespace(CompilationUnit unit) {
   _PublicNamespaceVisitor visitor = new _PublicNamespaceVisitor();
   unit.accept(visitor);
   return new UnlinkedPublicNamespaceBuilder(
       names: visitor.names, exports: visitor.exports, parts: visitor.parts);
 }
 
+/**
+ * Serialize a [Configuration] into a [UnlinkedConfigurationBuilder].
+ */
+UnlinkedConfigurationBuilder serializeConfiguration(
+    Configuration configuration) {
+  return new UnlinkedConfigurationBuilder(
+      name: configuration.name.components.map((i) => i.name).join('.'),
+      value: configuration.value?.stringValue ?? 'true',
+      uri: configuration.libraryUri.stringValue);
+}
+
 class _CombinatorEncoder extends SimpleAstVisitor<UnlinkedCombinatorBuilder> {
   _CombinatorEncoder();
 
   List<String> encodeNames(NodeList<SimpleIdentifier> names) =>
       names.map((SimpleIdentifier id) => id.name).toList();
 
   @override
   UnlinkedCombinatorBuilder visitHideCombinator(HideCombinator node) {
     return new UnlinkedCombinatorBuilder(hides: encodeNames(node.hiddenNames));
   }
@@ skipping 101 matching lines @@
       }
     }
   }
 
   @override
   visitExportDirective(ExportDirective node) {
     exports.add(new UnlinkedExportPublicBuilder(
         uri: node.uri.stringValue,
         combinators: node.combinators
             .map((Combinator c) => c.accept(new _CombinatorEncoder()))
-            .toList()));
+            .toList(),
+        configurations:
+            node.configurations.map(serializeConfiguration).toList()));
   }
 
   @override
   visitFunctionDeclaration(FunctionDeclaration node) {
     String name = node.name.name;
     if (node.isSetter) {
       name += '=';
     }
     addNameIfPublic(
         name,
@@ skipping 16 matching lines @@
 
   @override
   visitVariableDeclaration(VariableDeclaration node) {
     String name = node.name.name;
     addNameIfPublic(name, ReferenceKind.topLevelPropertyAccessor, 0);
     if (!node.isFinal && !node.isConst) {
       addNameIfPublic('$name=', ReferenceKind.topLevelPropertyAccessor, 0);
     }
   }
 }