Initial and partial summary support for extensions

Change-Id: Ibef5045b49e1334ef28c01508b2db5e2f50f32b3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/108183
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>

Author: bwilkerson

pkg/analyzer/lib/src/dart/element/element.dart

@@ -1780,7 +1780,9 @@ class CompilationUnitElementImpl extends UriReferencedElementImpl
     if (linkedNode != null) {
       // TODO(brianwilkerson) Implement this.
     } else if (_unlinkedUnit != null) {
-      // TODO(brianwilkerson) Implement this.
+      return _extensions = _unlinkedUnit.extensions
+          .map((e) => ExtensionElementImpl.forSerialized(e, this))
+          .toList(growable: false);
     }
 
     return _extensions ?? const <ExtensionElement>[];
@@ -4953,6 +4955,11 @@ class ExtensionElementImpl extends ElementImpl implements ExtensionElement {
       : _unlinkedExtension = null,
         super.forNode(name);
 
+  /// Initialize using the given serialized information.
+  ExtensionElementImpl.forSerialized(
+      this._unlinkedExtension, CompilationUnitElementImpl enclosingUnit)
+      : super.forSerialized(enclosingUnit);
+
   @override
   List<PropertyAccessorElement> get accessors {
     if (_accessors != null) {
@@ -5073,6 +5080,30 @@ class ExtensionElementImpl extends ElementImpl implements ExtensionElement {
     _methods = methods;
   }
 
+  @override
+  String get name {
+    if (linkedNode != null) {
+      return reference.name;
+    }
+    if (_unlinkedExtension != null) {
+      return _unlinkedExtension.name;
+    }
+    return super.name;
+  }
+
+  @override
+  int get nameOffset {
+    if (linkedNode != null) {
+      return enclosingUnit.linkedContext.getNameOffset(linkedNode);
+    }
+
+    int offset = super.nameOffset;
+    if (offset == 0 && _unlinkedExtension != null) {
+      return _unlinkedExtension.nameOffset;
+    }
+    return offset;
+  }
+
   @override
   List<TypeParameterElement> get typeParameters {
     if (_typeParameters != null) {
@@ -5094,17 +5125,16 @@ class ExtensionElementImpl extends ElementImpl implements ExtensionElement {
         return TypeParameterElementImpl.forLinkedNode(this, reference, node);
       }).toList();
     } else if (_unlinkedExtension != null) {
-      // TODO(brianwilkerson) Implement this.
-//      List<UnlinkedTypeParam> unlinkedParams =
-//          _unlinkedExtension?.typeParameters;
-//      if (unlinkedParams != null) {
-//        int numTypeParameters = unlinkedParams.length;
-//        _typeParameters = new List<TypeParameterElement>(numTypeParameters);
-//        for (int i = 0; i < numTypeParameters; i++) {
-//          _typeParameters[i] = new TypeParameterElementImpl.forSerialized(
-//              unlinkedParams[i], this);
-//        }
-//      }
+      List<UnlinkedTypeParam> unlinkedParams =
+          _unlinkedExtension?.typeParameters;
+      if (unlinkedParams != null) {
+        int numTypeParameters = unlinkedParams.length;
+        _typeParameters = new List<TypeParameterElement>(numTypeParameters);
+        for (int i = 0; i < numTypeParameters; i++) {
+          _typeParameters[i] = new TypeParameterElementImpl.forSerialized(
+              unlinkedParams[i], this);
+        }
+      }
     }
 
     return _typeParameters ?? const <TypeParameterElement>[];
@@ -9753,7 +9783,7 @@ class TypeParameterElementImpl extends ElementImpl
 
   /// Initialize using the given serialized information.
   TypeParameterElementImpl.forSerialized(
-      this._unlinkedTypeParam, TypeParameterizedElementMixin enclosingElement)
+      this._unlinkedTypeParam, ElementImpl enclosingElement)
       : super.forSerialized(enclosingElement);
 
   /// Initialize a newly created synthetic type parameter element to have the

pkg/analyzer/lib/src/dart/resolver/scope.dart

@@ -587,6 +587,9 @@ class LibraryScope extends EnclosedScope {
     for (ClassElement element in compilationUnit.enums) {
       define(element);
     }
+    for (ExtensionElement element in compilationUnit.extensions) {
+      define(element);
+    }
     for (FunctionElement element in compilationUnit.functions) {
       define(element);
     }

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

@@ -1075,6 +1075,7 @@ abstract class CompilationUnitElementForLink
   Map<String, ReferenceableElementForLink> _containedNames;
   List<TopLevelVariableElementForLink> _topLevelVariables;
   List<ClassElementForLink_Enum> _enums;
+  List<ExtensionElementForLink> _extensions;
   List<TopLevelFunctionElementForLink> _functions;
   List<PropertyAccessorElementForLink> _accessors;
   List<FunctionTypeAliasElementForLink> _functionTypeAliases;
@@ -1152,6 +1153,17 @@ abstract class CompilationUnitElementForLink
     return _enums;
   }
 
+  @override
+  List<ExtensionElementForLink> get extensions {
+    if (_extensions == null) {
+      _extensions = <ExtensionElementForLink>[];
+      for (UnlinkedExtension unlinkedExtension in _unlinkedUnit.extensions) {
+        _extensions.add(ExtensionElementForLink(this, unlinkedExtension));
+      }
+    }
+    return _extensions;
+  }
+
   @override
   List<TopLevelFunctionElementForLink> get functions {
     if (_functions == null) {
@@ -2553,6 +2565,21 @@ class ExprTypeComputer {
   }
 }
 
+class ExtensionElementForLink
+    with ReferenceableElementForLink
+    implements ExtensionElementImpl {
+  @override
+  final CompilationUnitElementForLink enclosingElement;
+
+  // TODO(brianwilkerson) Remove this field if it remains unreferenced.
+  final UnlinkedExtension _unlinkedExtension;
+
+  ExtensionElementForLink(this.enclosingElement, this._unlinkedExtension);
+
+  @override
+  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}
+
 /// Element representing a field resynthesized from a summary during
 /// linking.
 abstract class FieldElementForLink implements FieldElement {
@@ -3604,9 +3631,6 @@ abstract class LibraryElementForLink<
     }
   }
 
-  @override
-  bool get isNonNullableByDefault => _unlinkedDefiningUnit.isNNBD;
-
   @override
   ContextForLink get context => _linker.context;
 
@@ -3643,6 +3667,9 @@ abstract class LibraryElementForLink<
   @override
   bool get isInSdk => _absoluteUri.scheme == 'dart';
 
+  @override
+  bool get isNonNullableByDefault => _unlinkedDefiningUnit.isNNBD;
+
   @override
   bool get isSynthetic => _linkedLibrary == null;
 

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

@@ -238,6 +238,10 @@ class _SummarizeAstVisitor extends RecursiveAstVisitor {
   /// [UnlinkedClass.executables] or [UnlinkedExecutable.localFunctions].
   List<UnlinkedExecutableBuilder> executables = <UnlinkedExecutableBuilder>[];
 
+  /// List of objects which should be written to [UnlinkedUnit.extensions].
+  final List<UnlinkedExtensionBuilder> extensions =
+      <UnlinkedExtensionBuilder>[];
+
   /// List of objects which should be written to [UnlinkedUnit.exports].
   final List<UnlinkedExportNonPublicBuilder> exports =
       <UnlinkedExportNonPublicBuilder>[];
@@ -504,6 +508,7 @@ class _SummarizeAstVisitor extends RecursiveAstVisitor {
     b.classes = classes;
     b.enums = enums;
     b.executables = executables;
+    b.extensions = extensions;
     b.exports = exports;
     b.imports = unlinkedImports;
     b.mixins = mixins;
@@ -1183,6 +1188,41 @@ class _SummarizeAstVisitor extends RecursiveAstVisitor {
     exports.add(b);
   }
 
+  @override
+  visitExtensionDeclaration(ExtensionDeclaration node) {
+    int oldScopesLength = scopes.length;
+    enclosingClassHasConstConstructor = false;
+    List<UnlinkedExecutableBuilder> oldExecutables = executables;
+    executables = <UnlinkedExecutableBuilder>[];
+    List<UnlinkedVariableBuilder> oldVariables = variables;
+    variables = <UnlinkedVariableBuilder>[];
+    _TypeParameterScope typeParameterScope = new _TypeParameterScope();
+    scopes.add(typeParameterScope);
+
+    UnlinkedExtensionBuilder b = UnlinkedExtensionBuilder();
+    b.name = node.name?.name;
+    b.nameOffset = node.name?.offset ?? 0;
+    b.typeParameters =
+        serializeTypeParameters(node.typeParameters, typeParameterScope);
+    if (node.members != null) {
+      scopes.add(buildClassMemberScope(node.name?.name, node.members));
+      for (ClassMember member in node.members) {
+        member.accept(this);
+      }
+      scopes.removeLast();
+    }
+    b.executables = executables;
+    b.documentationComment = serializeDocumentation(node.documentationComment);
+    b.annotations = serializeAnnotations(node.metadata);
+    b.codeRange = serializeCodeRange(node);
+    extensions.add(b);
+
+    scopes.removeLast();
+    assert(scopes.length == oldScopesLength);
+    executables = oldExecutables;
+    variables = oldVariables;
+  }
+
   @override
   void visitFieldDeclaration(FieldDeclaration node) {
     serializeVariables(node.fields, node.staticKeyword != null,