Introduce ClassLike, MemberLike, FieldLike and FunctionLike

pkg/compiler/lib/src/elements/elements.dart

Index: pkg/compiler/lib/src/elements/elements.dart
diff --git a/pkg/compiler/lib/src/elements/elements.dart b/pkg/compiler/lib/src/elements/elements.dart
index e854e4d17c07de57c311944412d782f0acef2206..7b7ab77a74362fc385a374178417d285e8ceabad 100644
--- a/pkg/compiler/lib/src/elements/elements.dart
+++ b/pkg/compiler/lib/src/elements/elements.dart
@@ -128,6 +128,41 @@ abstract class Entity implements Spannable {
   String get name;
 }
 
+/// Stripped down super interface for class like entities.
+///
+/// Currently only [ClassElement] but later also kernel based Dart classes
+/// and/or Dart-in-JS classes.
+abstract class ClassLike extends Entity {

[Siggi Cherem (dart-lang), 2016/11/03 00:52:30]

maybe it is too early to tell, but how much from ClassElement do you think we'll
end up having here in the end?

[Johnni Winther, 2016/11/03 09:55:06]

Not much: I plan to move most queries on relations to other entities (like
sub/superrelation, members) into [ClosedWorld] and similar.

+  bool get isClosure;
+  void forEachInstanceField(f(ClassLike cls, FieldLike field),
+      {bool includeSuperAndInjectedMembers: false});
+}
+
+/// Stripped down super interface for member like entities, that is,
+/// constructors, methods, fields etc.
+///
+/// Currently only [MemberElement] but later also kernel based Dart members
+/// and/or Dart-in-JS properties.
+abstract class MemberLike extends Entity {
+  bool get isField;
+  bool get isFunction;
+  bool get isGetter;
+  bool get isAssignable;
+  ClassLike get enclosingClass;
+}
+
+/// Stripped down super interface for field like entities.
+///
+/// Currently only [FieldElement] but later also kernel based Dart fields
+/// and/or Dart-in-JS field-like properties.
+abstract class FieldLike extends MemberLike {}
+
+/// Stripped down super interface for function like entities.
+///
+/// Currently only [FieldElement] but later also kernel based Dart constructors
+/// and methods and/or Dart-in-JS function-like properties.
+abstract class FunctionLike extends MemberLike {}

[Siggi Cherem (dart-lang), 2016/11/03 00:52:30]

I'm not yet convinced on using the "XLike" names :)

Other ideas:
- overload "Class, Member, Field", (or ClassElement, MemberELement, ...), move
them to a new library (e.g. new_elements), and always use them with a prefix
(e.g. n)
- use the "Entity" suffix instead? (e.g. "ClassEntity")

[Johnni Winther, 2016/11/03 09:55:06]

Moved to 'entities.dart', use 'Entity' as suffix.

+
 /**
  * A declared element of a program.
  *
@@ -1047,7 +1082,8 @@ abstract class ExecutableElement extends Element
 ///
 /// A [MemberElement] is the outermost executable element for any executable
 /// context.
-abstract class MemberElement extends Element implements ExecutableElement {
+abstract class MemberElement extends Element
+    implements ExecutableElement, MemberLike {
   /// The local functions defined within this member.
   List<FunctionElement> get nestedClosures;
 
@@ -1100,7 +1136,8 @@ abstract class LocalVariableElement extends VariableElement
     implements LocalElement {}
 
 /// A top-level, static or instance field.
-abstract class FieldElement extends VariableElement implements MemberElement {}
+abstract class FieldElement extends VariableElement
+    implements MemberElement, FieldLike {}
 
 /// A parameter-like element of a function signature.
 ///
@@ -1291,15 +1328,15 @@ class AsyncMarker {
 }
 
 /// A top level, static or instance function.
-abstract class MethodElement extends FunctionElement implements MemberElement {}
+abstract class MethodElement extends FunctionElement
+    implements MemberElement, FunctionLike {}
 
 /// A local function or closure (anonymous local function).
 abstract class LocalFunctionElement extends FunctionElement
     implements LocalElement {}
 
 /// A constructor.
-abstract class ConstructorElement extends FunctionElement
-    implements MemberElement {
+abstract class ConstructorElement extends MethodElement {
   /// Returns `true` if [effectiveTarget] has been computed for this
   /// constructor.
   bool get hasEffectiveTarget;
@@ -1470,7 +1507,7 @@ abstract class TypeDeclarationElement extends GenericElement {
 }
 
 abstract class ClassElement extends TypeDeclarationElement
-    implements ScopeContainerElement {
+    implements ScopeContainerElement, ClassLike {
   /// The length of the longest inheritance path from [:Object:].
   int get hierarchyDepth;