Use summary IDL file for interface classes.

pkg/analyzer/lib/src/summary/idl.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.
 
 /**
- * This file is an "idl" style description of the summary format.  It is not
- * executed directly; instead it is parsed and transformed into code that
- * implements the summary format.
+ * This file is an "idl" style description of the summary format.  It
+ * contains abstract classes which declare the interface for reading data from
+ * summaries.  It is parsed and transformed into code that implements the
+ * summary format.
  *
- * The code generation process introduces the following non-typical semantics:
- * - Fields of type List are never null, and have a default value of the empty
- *   list.
- * - Fields of type int are unsigned 32-bit integers, never null, and have a
- *   default value of zero.
- * - Fields of type String are never null, and have a default value of ''.
- * - Fields of type bool are never null, and have a default value of false.
- * - Fields whose type is an enum are never null, and have a default value of
- *   the first value declared in the enum.
+ * The code generation process introduces the following semantics:
+ * - Getters of type List never return null, and have a default value of the
+ *   empty list.
+ * - Getters of type int return unsigned 32-bit integers, never null, and have
+ *   a default value of zero.
+ * - Getters of type String never return null, and have a default value of ''.
+ * - Getters of type bool never return null, and have a default value of false.
+ * - Getters whose type is an enum never return null, and have a default value
+ *   of the first value declared in the enum.
  *
  * Terminology used in this document:
  * - "Unlinked" refers to information that can be determined from reading a
  *   single .dart file in isolation.
  * - "Prelinked" refers to information that can be determined from the defining
  *   compilation unit of a library, plus direct imports, plus the transitive
  *   closure of exports reachable from those libraries, plus all part files
  *   constituting those libraries.
  * - "Linked" refers to all other information; in theory, this information may
  *   depend on all files in the transitive import/export closure.  However, in
  *   practice we expect that the number of additional dependencies will usually
  *   be small, since the additional dependencies only need to be consulted for
  *   type propagation, type inference, and constant evaluation, which typically
  *   have short dependency chains.
  *
  * Since we expect "linked" and "prelinked" dependencies to be similar, we only
  * rarely distinguish between them; most information is that is not "unlinked"
  * is typically considered "linked" for simplicity.
  *
  * Except as otherwise noted, synthetic elements are not stored in the summary;
  * they are re-synthesized at the time the summary is read.
  */
 library analyzer.tool.summary.idl;
 
+import 'base.dart' as base;
+import 'format.dart' as generated;
+
 /**
  * Annotation describing information which is not part of Dart semantics; in
  * other words, if this information (or any information it refers to) changes,
  * static analysis and runtime behavior of the library are unaffected.
  *
  * TODO(paulberry): some informative information is currently missing from the
  * summary format.
  */
 const informative = null;
 
@@ skipping 10 matching lines @@
 /**
  * Annotation describing a class which can be the top level object in an
  * encoded summary.
  */
 const topLevel = null;
 
 /**
  * Summary information about a reference to a an entity such as a type, top
  * level executable, or executable within a class.
  */
-class EntityRef {
+abstract class EntityRef extends base.SummaryClass {
   /**
    * If this [EntityRef] is contained within [LinkedUnit.types], slot id (which
    * is unique within the compilation unit) identifying the target of type
    * propagation or type inference with which this [EntityRef] is associated.
    *
    * Otherwise zero.
    */
-  int slot;
+  int get slot;
 
   /**
    * Index into [UnlinkedUnit.references] for the entity being referred to, or
    * zero if this is a reference to a type parameter.
    */
-  int reference;
+  int get reference;
 
   /**
    * If this is a reference to a type parameter, one-based index into the list
    * of [UnlinkedTypeParam]s currently in effect.  Indexing is done using De
    * Bruijn index conventions; that is, innermost parameters come first, and
    * if a class or method has multiple parameters, they are indexed from right
    * to left.  So for instance, if the enclosing declaration is
    *
    *     class C<T,U> {
    *       m<V,W> {
    *         ...
    *       }
    *     }
    *
    * Then [paramReference] values of 1, 2, 3, and 4 represent W, V, U, and T,
    * respectively.
    *
    * If the type being referred to is not a type parameter, [paramReference] is
    * zero.
    */
-  int paramReference;
+  int get paramReference;
 
   /**
    * If this is a reference to a function type implicitly defined by a
    * function-typed parameter, a list of zero-based indices indicating the path
    * from the entity referred to by [reference] to the appropriate type
    * parameter.  Otherwise the empty list.
    *
    * If there are N indices in this list, then the entity being referred to is
    * the function type implicitly defined by a function-typed parameter of a
    * function-typed parameter, to N levels of nesting.  The first index in the
    * list refers to the outermost level of nesting; for example if [reference]
    * refers to the entity defined by:
    *
    *     void f(x, void g(y, z, int h(String w))) { ... }
    *
    * Then to refer to the function type implicitly defined by parameter `h`
    * (which is parameter 2 of parameter 1 of `f`), then
    * [implicitFunctionTypeIndices] should be [1, 2].
    *
    * Note that if the entity being referred to is a generic method inside a
    * generic class, then the type arguments in [typeArguments] are applied
    * first to the class and then to the method.
    */
-  List<int> implicitFunctionTypeIndices;
+  List<int> get implicitFunctionTypeIndices;
 
   /**
    * If this is an instantiation of a generic type or generic executable, the
    * type arguments used to instantiate it.  Trailing type arguments of type
    * `dynamic` are omitted.
    */
-  List<EntityRef> typeArguments;
+  List<EntityRef> get typeArguments;
 }
 
 /**
  * Information about a dependency that exists between one library and another
  * due to an "import" declaration.
  */
-class LinkedDependency {
+abstract class LinkedDependency extends base.SummaryClass {
   /**
    * The relative URI of the dependent library.  This URI is relative to the
    * importing library, even if there are intervening `export` declarations.
    * So, for example, if `a.dart` imports `b/c.dart` and `b/c.dart` exports
    * `d/e.dart`, the URI listed for `a.dart`'s dependency on `e.dart` will be
    * `b/d/e.dart`.
    */
-  String uri;
+  String get uri;
 
   /**
    * URI for the compilation units listed in the library's `part` declarations.
    * These URIs are relative to the importing library.
    */
-  List<String> parts;
+  List<String> get parts;
 }
 
 /**
  * Information about a single name in the export namespace of the library that
  * is not in the public namespace.
  */
-class LinkedExportName {
+abstract class LinkedExportName extends base.SummaryClass {
   /**
    * Name of the exported entity.  For an exported setter, this name includes
    * the trailing '='.
    */
-  String name;
+  String get name;
 
   /**
    * Index into [LinkedLibrary.dependencies] for the library in which the
    * entity is defined.
    */
-  int dependency;
+  int get dependency;
 
   /**
    * Integer index indicating which unit in the exported library contains the
    * definition of the entity.  As with indices into [LinkedLibrary.units],
    * zero represents the defining compilation unit, and nonzero values
    * represent parts in the order of the corresponding `part` declarations.
    */
-  int unit;
+  int get unit;
 
   /**
    * The kind of the entity being referred to.
    */
-  ReferenceKind kind;
+  ReferenceKind get kind;
 }
 
 /**
  * Linked summary of a library.
  */
 @topLevel
-class LinkedLibrary {
+abstract class LinkedLibrary extends base.SummaryClass {
+  factory LinkedLibrary.fromBuffer(List<int> buffer) =>
+      generated.readLinkedLibrary(buffer);
+
   /**
    * The linked summary of all the compilation units constituting the
    * library.  The summary of the defining compilation unit is listed first,
    * followed by the summary of each part, in the order of the `part`
    * declarations in the defining compilation unit.
    */
-  List<LinkedUnit> units;
+  List<LinkedUnit> get units;
 
   /**
    * The libraries that this library depends on (either via an explicit import
    * statement or via the implicit dependencies on `dart:core` and
    * `dart:async`).  The first element of this array is a pseudo-dependency
    * representing the library itself (it is also used for `dynamic` and
    * `void`).  This is followed by elements representing "prelinked"
    * dependencies (direct imports and the transitive closure of exports).
    * After the prelinked dependencies are elements representing "linked"
    * dependencies.
    *
    * A library is only included as a "linked" dependency if it is a true
    * dependency (e.g. a propagated or inferred type or constant value
    * implicitly refers to an element declared in the library) or
    * anti-dependency (e.g. the result of type propagation or type inference
    * depends on the lack of a certain declaration in the library).
    */
-  List<LinkedDependency> dependencies;
+  List<LinkedDependency> get dependencies;
 
   /**
    * For each import in [UnlinkedUnit.imports], an index into [dependencies]
    * of the library being imported.
    */
-  List<int> importDependencies;
+  List<int> get importDependencies;
 
   /**
    * Information about entities in the export namespace of the library that are
    * not in the public namespace of the library (that is, entities that are
    * brought into the namespace via `export` directives).
    *
    * Sorted by name.
    */
-  List<LinkedExportName> exportNames;
+  List<LinkedExportName> get exportNames;
 
   /**
    * The number of elements in [dependencies] which are not "linked"
    * dependencies (that is, the number of libraries in the direct imports plus
    * the transitive closure of exports, plus the library itself).
    */
-  int numPrelinkedDependencies;
+  int get numPrelinkedDependencies;
 }
 
 /**
  * Information about the resolution of an [UnlinkedReference].
  */
-class LinkedReference {
+abstract class LinkedReference extends base.SummaryClass {
   /**
    * Index into [LinkedLibrary.dependencies] indicating which imported library
    * declares the entity being referred to.
    *
    * Zero if this entity is contained within another entity (e.g. a class
    * member).
    */
-  int dependency;
+  int get dependency;
 
   /**
    * The kind of the entity being referred to.  For the pseudo-types `dynamic`
    * and `void`, the kind is [ReferenceKind.classOrEnum].
    */
-  ReferenceKind kind;
+  ReferenceKind get kind;
 
   /**
    * Integer index indicating which unit in the imported library contains the
    * definition of the entity.  As with indices into [LinkedLibrary.units],
    * zero represents the defining compilation unit, and nonzero values
    * represent parts in the order of the corresponding `part` declarations.
    *
    * Zero if this entity is contained within another entity (e.g. a class
    * member).
    */
-  int unit;
+  int get unit;
 
   /**
    * If the entity being referred to is generic, the number of type parameters
    * it accepts.  Otherwise zero.
    */
-  int numTypeParameters;
+  int get numTypeParameters;
 
   /**
    * If this [LinkedReference] doesn't have an associated [UnlinkedReference],
    * name of the entity being referred to.  For the pseudo-type `dynamic`, the
    * string is "dynamic".  For the pseudo-type `void`, the string is "void".
    */
-  String name;
+  String get name;
 
   /**
    * If this [LinkedReference] doesn't have an associated [UnlinkedReference],
    * and the entity being referred to is contained within another entity, index
    * of the containing entity.  This behaves similarly to
    * [UnlinkedReference.prefixReference], however it is only used for class
    * members, not for prefixed imports.
    *
    * Containing references must always point backward; that is, for all i, if
    * LinkedUnit.references[i].containingReference != 0, then
    * LinkedUnit.references[i].containingReference < i.
    */
-  int containingReference;
+  int get containingReference;
 }
 
 /**
  * Linked summary of a compilation unit.
  */
-class LinkedUnit {
+abstract class LinkedUnit extends base.SummaryClass {
   /**
    * Information about the resolution of references within the compilation
    * unit.  Each element of [UnlinkedUnit.references] has a corresponding
    * element in this list (at the same index).  If this list has additional
    * elements beyond the number of elements in [UnlinkedUnit.references], those
    * additional elements are references that are only referred to implicitly
    * (e.g. elements involved in inferred or propagated types).
    */
-  List<LinkedReference> references;
+  List<LinkedReference> get references;
 
   /**
    * List associating slot ids found inside the unlinked summary for the
    * compilation unit with propagated and inferred types.
    */
-  List<EntityRef> types;
+  List<EntityRef> get types;
 }
 
 /**
  * Enum used to indicate the kind of entity referred to by a
  * [LinkedReference].
  */
 enum ReferenceKind {
   /**
    * The entity is a class or enum.
    */
@@ skipping 44 matching lines @@
   /**
    * The entity being referred to does not exist.
    */
   unresolved
 }
 
 /**
  * Information about SDK.
  */
 @topLevel
-class SdkBundle {
+abstract class SdkBundle extends base.SummaryClass {
+  factory SdkBundle.fromBuffer(List<int> buffer) =>
+      generated.readSdkBundle(buffer);
+
   /**
    * The list of URIs of items in [linkedLibraries], e.g. `dart:core`.
    */
-  List<String> linkedLibraryUris;
+  List<String> get linkedLibraryUris;
 
   /**
    * Linked libraries.
    */
-  List<LinkedLibrary> linkedLibraries;
+  List<LinkedLibrary> get linkedLibraries;
 
   /**
    * The list of URIs of items in [unlinkedUnits], e.g. `dart:core/bool.dart`.
    */
-  List<String> unlinkedUnitUris;
+  List<String> get unlinkedUnitUris;
 
   /**
    * Unlinked information for the compilation units constituting the SDK.
    */
-  List<UnlinkedUnit> unlinkedUnits;
+  List<UnlinkedUnit> get unlinkedUnits;
 }
 
 /**
  * Unlinked summary information about a class declaration.
  */
-class UnlinkedClass {
+abstract class UnlinkedClass extends base.SummaryClass {
   /**
    * Name of the class.
    */
-  String name;
+  String get name;
 
   /**
    * Offset of the class name relative to the beginning of the file.
    */
   @informative
-  int nameOffset;
+  int get nameOffset;
 
   /**
    * Documentation comment for the class, or `null` if there is no
    * documentation comment.
    */
   @informative
-  UnlinkedDocumentationComment documentationComment;
+  UnlinkedDocumentationComment get documentationComment;
 
   /**
    * Type parameters of the class, if any.
    */
-  List<UnlinkedTypeParam> typeParameters;
+  List<UnlinkedTypeParam> get typeParameters;
 
   /**
    * Supertype of the class, or `null` if either (a) the class doesn't
    * explicitly declare a supertype (and hence has supertype `Object`), or (b)
    * the class *is* `Object` (and hence has no supertype).
    */
-  EntityRef supertype;
+  EntityRef get supertype;
 
   /**
    * Mixins appearing in a `with` clause, if any.
    */
-  List<EntityRef> mixins;
+  List<EntityRef> get mixins;
 
   /**
    * Interfaces appearing in an `implements` clause, if any.
    */
-  List<EntityRef> interfaces;
+  List<EntityRef> get interfaces;
 
   /**
    * Field declarations contained in the class.
    */
-  List<UnlinkedVariable> fields;
+  List<UnlinkedVariable> get fields;
 
   /**
    * Executable objects (methods, getters, and setters) contained in the class.
    */
-  List<UnlinkedExecutable> executables;
+  List<UnlinkedExecutable> get executables;
 
   /**
    * Indicates whether the class is declared with the `abstract` keyword.
    */
-  bool isAbstract;
+  bool get isAbstract;
 
   /**
    * Indicates whether the class is declared using mixin application syntax.
    */
-  bool isMixinApplication;
+  bool get isMixinApplication;
 
   /**
    * Indicates whether this class is the core "Object" class (and hence has no
    * supertype)
    */
-  bool hasNoSupertype;
+  bool get hasNoSupertype;
 }
 
 /**
  * Unlinked summary information about a `show` or `hide` combinator in an
  * import or export declaration.
  */
-class UnlinkedCombinator {
+abstract class UnlinkedCombinator extends base.SummaryClass {
   /**
    * List of names which are shown.  Empty if this is a `hide` combinator.
    */
-  List<String> shows;
+  List<String> get shows;
 
   /**
    * List of names which are hidden.  Empty if this is a `show` combinator.
    */
-  List<String> hides;
+  List<String> get hides;
 }
 
 /**
  * Unlinked summary information about a compile-time constant expression, or a
  * potentially constant expression.
  *
  * Constant expressions are represented using a simple stack-based language
  * where [operations] is a sequence of operations to execute starting with an
  * empty stack.  Once all operations have been executed, the stack should
  * contain a single value which is the value of the constant.  Note that some
  * operations consume additional data from the other fields of this class.
  */
-class UnlinkedConst {
+abstract class UnlinkedConst extends base.SummaryClass {
   /**
    * Sequence of operations to execute (starting with an empty stack) to form
    * the constant value.
    */
-  List<UnlinkedConstOperation> operations;
+  List<UnlinkedConstOperation> get operations;
 
   /**
    * Sequence of unsigned 32-bit integers consumed by the operations
    * `pushArgument`, `pushInt`, `shiftOr`, `concatenate`, `invokeConstructor`,
    * `makeList`, and `makeMap`.
    */
-  List<int> ints;
+  List<int> get ints;
 
   /**
    * Sequence of 64-bit doubles consumed by the operation `pushDouble`.
    */
-  List<double> doubles;
+  List<double> get doubles;
 
   /**
    * Sequence of strings consumed by the operations `pushString` and
    * `invokeConstructor`.
    */
-  List<String> strings;
+  List<String> get strings;
 
   /**
    * Sequence of language constructs consumed by the operations
    * `pushReference`, `invokeConstructor`, `makeList`, and `makeMap`.  Note
    * that in the case of `pushReference` (and sometimes `invokeConstructor` the
    * actual entity being referred to may be something other than a type.
    */
-  List<EntityRef> references;
+  List<EntityRef> get references;
 }
 
 /**
  * Enum representing the various kinds of operations which may be performed to
  * produce a constant value.  These options are assumed to execute in the
  * context of a stack which is initially empty.
  */
 enum UnlinkedConstOperation {
   /**
    * Push the next value from [UnlinkedConst.ints] (a 32-bit unsigned integer)
@@ skipping 269 matching lines @@
   /**
    * Pop the top value from the stack, evaluate `v.length`, and push the result
    * back onto the stack.
    */
   length,
 }
 
 /**
  * Unlinked summary information about a documentation comment.
  */
-class UnlinkedDocumentationComment {
+abstract class UnlinkedDocumentationComment extends base.SummaryClass {
   /**
    * Text of the documentation comment, with '\r\n' replaced by '\n'.
    *
    * References appearing within the doc comment in square brackets are not
    * specially encoded.
    */
-  String text;
+  String get text;
 
   /**
    * Offset of the beginning of the documentation comment relative to the
    * beginning of the file.
    */
-  int offset;
+  int get offset;
 
   /**
    * Length of the documentation comment (prior to replacing '\r\n' with '\n').
    */
-  int length;
+  int get length;
 }
 
 /**
  * Unlinked summary information about an enum declaration.
  */
-class UnlinkedEnum {
+abstract class UnlinkedEnum extends base.SummaryClass {
   /**
    * Name of the enum type.
    */
-  String name;
+  String get name;
 
   /**
    * Offset of the enum name relative to the beginning of the file.
    */
   @informative
-  int nameOffset;
+  int get nameOffset;
 
   /**
    * Documentation comment for the enum, or `null` if there is no documentation
    * comment.
    */
   @informative
-  UnlinkedDocumentationComment documentationComment;
+  UnlinkedDocumentationComment get documentationComment;
 
   /**
    * Values listed in the enum declaration, in declaration order.
    */
-  List<UnlinkedEnumValue> values;
+  List<UnlinkedEnumValue> get values;
 }
 
 /**
  * Unlinked summary information about a single enumerated value in an enum
  * declaration.
  */
-class UnlinkedEnumValue {
+abstract class UnlinkedEnumValue extends base.SummaryClass {
   /**
    * Name of the enumerated value.
    */
-  String name;
+  String get name;
 
   /**
    * Offset of the enum value name relative to the beginning of the file.
    */
   @informative
-  int nameOffset;
+  int get nameOffset;
 
   /**
    * Documentation comment for the enum value, or `null` if there is no
    * documentation comment.
    */
   @informative
-  UnlinkedDocumentationComment documentationComment;
+  UnlinkedDocumentationComment get documentationComment;
 }
 
 /**
  * Unlinked summary information about a function, method, getter, or setter
  * declaration.
  */
-class UnlinkedExecutable {
+abstract class UnlinkedExecutable extends base.SummaryClass {
   /**
    * Name of the executable.  For setters, this includes the trailing "=".  For
    * named constructors, this excludes the class name and excludes the ".".
    * For unnamed constructors, this is the empty string.
    */
-  String name;
+  String get name;
 
   /**
    * Offset of the executable name relative to the beginning of the file.  For
    * named constructors, this excludes the class name and excludes the ".".
    * For unnamed constructors, this is the offset of the class name (i.e. the
    * offset of the second "C" in "class C { C(); }").
    */
   @informative
-  int nameOffset;
+  int get nameOffset;
 
   /**
    * Documentation comment for the executable, or `null` if there is no
    * documentation comment.
    */
   @informative
-  UnlinkedDocumentationComment documentationComment;
+  UnlinkedDocumentationComment get documentationComment;
 
   /**
    * Type parameters of the executable, if any.  Empty if support for generic
    * method syntax is disabled.
    */
-  List<UnlinkedTypeParam> typeParameters;
+  List<UnlinkedTypeParam> get typeParameters;
 
   /**
    * Declared return type of the executable.  Absent if the executable is a
    * constructor or the return type is implicit.
    */
-  EntityRef returnType;
+  EntityRef get returnType;
 
   /**
    * Parameters of the executable, if any.  Note that getters have no
    * parameters (hence this will be the empty list), and setters have a single
    * parameter.
    */
-  List<UnlinkedParam> parameters;
+  List<UnlinkedParam> get parameters;
 
   /**
    * The kind of the executable (function/method, getter, setter, or
    * constructor).
    */
-  UnlinkedExecutableKind kind;
+  UnlinkedExecutableKind get kind;
 
   /**
    * Indicates whether the executable is declared using the `abstract` keyword.
    */
-  bool isAbstract;
+  bool get isAbstract;
 
   /**
    * Indicates whether the executable is declared using the `static` keyword.
    *
    * Note that for top level executables, this flag is false, since they are
    * not declared using the `static` keyword (even though they are considered
    * static for semantic purposes).
    */
-  bool isStatic;
+  bool get isStatic;
 
   /**
    * Indicates whether the executable is declared using the `const` keyword.
    */
-  bool isConst;
+  bool get isConst;
 
   /**
    * Indicates whether the executable is declared using the `factory` keyword.
    */
-  bool isFactory;
+  bool get isFactory;
 
   /**
    * Indicates whether the executable is declared using the `external` keyword.
    */
-  bool isExternal;
+  bool get isExternal;
 
   /**
    * If this executable's return type is inferrable, nonzero slot id
    * identifying which entry in [LinkedLibrary.types] contains the inferred
    * return type.  If there is no matching entry in [LinkedLibrary.types], then
    * no return type was inferred for this variable, so its static type is
    * `dynamic`.
    */
-  int inferredReturnTypeSlot;
+  int get inferredReturnTypeSlot;
 }
 
 /**
  * Enum used to indicate the kind of an executable.
  */
 enum UnlinkedExecutableKind {
   /**
    * Executable is a function or method.
    */
   functionOrMethod,
@@ skipping 11 matching lines @@
   /**
    * Executable is a constructor.
    */
   constructor
 }
 
 /**
  * Unlinked summary information about an export declaration (stored outside
  * [UnlinkedPublicNamespace]).
  */
-class UnlinkedExportNonPublic {
+abstract class UnlinkedExportNonPublic extends base.SummaryClass {
   /**
    * Offset of the "export" keyword.
    */
   @informative
-  int offset;
+  int get offset;
 
   /**
    * Offset of the URI string (including quotes) relative to the beginning of
    * the file.
    */
   @informative
-  int uriOffset;
+  int get uriOffset;
 
   /**
    * End of the URI string (including quotes) relative to the beginning of the
    * file.
    */
   @informative
-  int uriEnd;
+  int get uriEnd;
 }
 
 /**
  * Unlinked summary information about an export declaration (stored inside
  * [UnlinkedPublicNamespace]).
  */
-class UnlinkedExportPublic {
+abstract class UnlinkedExportPublic extends base.SummaryClass {
   /**
    * URI used in the source code to reference the exported library.
    */
-  String uri;
+  String get uri;
 
   /**
    * Combinators contained in this import declaration.
    */
-  List<UnlinkedCombinator> combinators;
+  List<UnlinkedCombinator> get combinators;
 }
 
 /**
  * Unlinked summary information about an import declaration.
  */
-class UnlinkedImport {
+abstract class UnlinkedImport extends base.SummaryClass {
   /**
    * URI used in the source code to reference the imported library.
    */
-  String uri;
+  String get uri;
 
   /**
    * If [isImplicit] is false, offset of the "import" keyword.  If [isImplicit]
    * is true, zero.
    */
   @informative
-  int offset;
+  int get offset;
 
   /**
    * Index into [UnlinkedUnit.references] of the prefix declared by this
    * import declaration, or zero if this import declaration declares no prefix.
    *
    * Note that multiple imports can declare the same prefix.
    */
-  int prefixReference;
+  int get prefixReference;
 
   /**
    * Combinators contained in this import declaration.
    */
-  List<UnlinkedCombinator> combinators;
+  List<UnlinkedCombinator> get combinators;
 
   /**
    * Indicates whether the import declaration uses the `deferred` keyword.
    */
-  bool isDeferred;
+  bool get isDeferred;
 
   /**
    * Indicates whether the import declaration is implicit.
    */
-  bool isImplicit;
+  bool get isImplicit;
 
   /**
    * Offset of the URI string (including quotes) relative to the beginning of
    * the file.  If [isImplicit] is true, zero.
    */
   @informative
-  int uriOffset;
+  int get uriOffset;
 
   /**
    * End of the URI string (including quotes) relative to the beginning of the
    * file.  If [isImplicit] is true, zero.
    */
   @informative
-  int uriEnd;
+  int get uriEnd;
 
   /**
    * Offset of the prefix name relative to the beginning of the file, or zero
    * if there is no prefix.
    */
   @informative
-  int prefixOffset;
+  int get prefixOffset;
 }
 
 /**
  * Unlinked summary information about a function parameter.
  */
-class UnlinkedParam {
+abstract class UnlinkedParam extends base.SummaryClass {
   /**
    * Name of the parameter.
    */
-  String name;
+  String get name;
 
   /**
    * Offset of the parameter name relative to the beginning of the file.
    */
   @informative
-  int nameOffset;
+  int get nameOffset;
 
   /**
    * If [isFunctionTyped] is `true`, the declared return type.  If
    * [isFunctionTyped] is `false`, the declared type.  Absent if the type is
    * implicit.
    */
-  EntityRef type;
+  EntityRef get type;
 
   /**
    * If [isFunctionTyped] is `true`, the parameters of the function type.
    */
-  List<UnlinkedParam> parameters;
+  List<UnlinkedParam> get parameters;
 
   /**
    * Kind of the parameter.
    */
-  UnlinkedParamKind kind;
+  UnlinkedParamKind get kind;
 
   /**
    * Indicates whether this is a function-typed parameter.
    */
-  bool isFunctionTyped;
+  bool get isFunctionTyped;
 
   /**
    * Indicates whether this is an initializing formal parameter (i.e. it is
    * declared using `this.` syntax).
    */
-  bool isInitializingFormal;
+  bool get isInitializingFormal;
 
   /**
    * If this parameter's type is inferrable, nonzero slot id identifying which
    * entry in [LinkedLibrary.types] contains the inferred type.  If there is no
    * matching entry in [LinkedLibrary.types], then no type was inferred for
    * this variable, so its static type is `dynamic`.
    *
    * Note that although strong mode considers initializing formals to be
    * inferrable, they are not marked as such in the summary; if their type is
    * not specified, they always inherit the static type of the corresponding
    * field.
    */
-  int inferredTypeSlot;
+  int get inferredTypeSlot;
 }
 
 /**
  * Enum used to indicate the kind of a parameter.
  */
 enum UnlinkedParamKind {
   /**
    * Parameter is required.
    */
   required,
 
   /**
    * Parameter is positional optional (enclosed in `[]`)
    */
   positional,
 
   /**
    * Parameter is named optional (enclosed in `{}`)
    */
   named
 }
 
 /**
  * Unlinked summary information about a part declaration.
  */
-class UnlinkedPart {
+abstract class UnlinkedPart extends base.SummaryClass {
   /**
    * Offset of the URI string (including quotes) relative to the beginning of
    * the file.
    */
   @informative
-  int uriOffset;
+  int get uriOffset;
 
   /**
    * End of the URI string (including quotes) relative to the beginning of the
    * file.
    */
   @informative
-  int uriEnd;
+  int get uriEnd;
 }
 
 /**
  * Unlinked summary information about a specific name contributed by a
  * compilation unit to a library's public namespace.
  *
  * TODO(paulberry): some of this information is redundant with information
  * elsewhere in the summary.  Consider reducing the redundancy to reduce
  * summary size.
  */
-class UnlinkedPublicName {
+abstract class UnlinkedPublicName extends base.SummaryClass {
   /**
    * The name itself.
    */
-  String name;
+  String get name;
 
   /**
    * The kind of object referred to by the name.
    */
-  ReferenceKind kind;
+  ReferenceKind get kind;
 
   /**
    * If the entity being referred to is generic, the number of type parameters
    * it accepts.  Otherwise zero.
    */
-  int numTypeParameters;
+  int get numTypeParameters;
 
   /**
    * If this [UnlinkedPublicName] is a class, the list of members which can be
    * referenced from constants - static constant fields, static methods, and
    * constructors.  Otherwise empty.
    */
-  List<UnlinkedPublicName> constMembers;
+  List<UnlinkedPublicName> get constMembers;
 }
 
 /**
  * Unlinked summary information about what a compilation unit contributes to a
  * library's public namespace.  This is the subset of [UnlinkedUnit] that is
  * required from dependent libraries in order to perform prelinking.
  */
 @topLevel
-class UnlinkedPublicNamespace {
+abstract class UnlinkedPublicNamespace extends base.SummaryClass {
+  factory UnlinkedPublicNamespace.fromBuffer(List<int> buffer) =>
+      generated.readUnlinkedPublicNamespace(buffer);
+
   /**
    * Public names defined in the compilation unit.
    *
    * TODO(paulberry): consider sorting these names to reduce unnecessary
    * relinking.
    */
-  List<UnlinkedPublicName> names;
+  List<UnlinkedPublicName> get names;
 
   /**
    * Export declarations in the compilation unit.
    */
-  List<UnlinkedExportPublic> exports;
+  List<UnlinkedExportPublic> get exports;
 
   /**
    * URIs referenced by part declarations in the compilation unit.
    */
-  List<String> parts;
+  List<String> get parts;
 }
 
 /**
  * Unlinked summary information about a name referred to in one library that
  * might be defined in another.
  */
-class UnlinkedReference {
+abstract class UnlinkedReference extends base.SummaryClass {
   /**
    * Name of the entity being referred to.  For the pseudo-type `dynamic`, the
    * string is "dynamic".  For the pseudo-type `void`, the string is "void".
    */
-  String name;
+  String get name;
 
   /**
    * Prefix used to refer to the entity, or zero if no prefix is used.  This is
    * an index into [UnlinkedUnit.references].
    *
    * Prefix references must always point backward; that is, for all i, if
    * UnlinkedUnit.references[i].prefixReference != 0, then
    * UnlinkedUnit.references[i].prefixReference < i.
    */
-  int prefixReference;
+  int get prefixReference;
 }
 
 /**
  * Unlinked summary information about a typedef declaration.
  */
-class UnlinkedTypedef {
+abstract class UnlinkedTypedef extends base.SummaryClass {
   /**
    * Name of the typedef.
    */
-  String name;
+  String get name;
 
   /**
    * Offset of the typedef name relative to the beginning of the file.
    */
   @informative
-  int nameOffset;
+  int get nameOffset;
 
   /**
    * Documentation comment for the typedef, or `null` if there is no
    * documentation comment.
    */
   @informative
-  UnlinkedDocumentationComment documentationComment;
+  UnlinkedDocumentationComment get documentationComment;
 
   /**
    * Type parameters of the typedef, if any.
    */
-  List<UnlinkedTypeParam> typeParameters;
+  List<UnlinkedTypeParam> get typeParameters;
 
   /**
    * Return type of the typedef.
    */
-  EntityRef returnType;
+  EntityRef get returnType;
 
   /**
    * Parameters of the executable, if any.
    */
-  List<UnlinkedParam> parameters;
+  List<UnlinkedParam> get parameters;
 }
 
 /**
  * Unlinked summary information about a type parameter declaration.
  */
-class UnlinkedTypeParam {
+abstract class UnlinkedTypeParam extends base.SummaryClass {
   /**
    * Name of the type parameter.
    */
-  String name;
+  String get name;
 
   /**
    * Offset of the type parameter name relative to the beginning of the file.
    */
   @informative
-  int nameOffset;
+  int get nameOffset;
 
   /**
    * Bound of the type parameter, if a bound is explicitly declared.  Otherwise
    * null.
    */
-  EntityRef bound;
+  EntityRef get bound;
 }
 
 /**
  * Unlinked summary information about a compilation unit ("part file").
  */
 @topLevel
-class UnlinkedUnit {
+abstract class UnlinkedUnit extends base.SummaryClass {
+  factory UnlinkedUnit.fromBuffer(List<int> buffer) =>
+      generated.readUnlinkedUnit(buffer);
+
   /**
    * Name of the library (from a "library" declaration, if present).
    */
-  String libraryName;
+  String get libraryName;
 
   /**
    * Offset of the library name relative to the beginning of the file (or 0 if
    * the library has no name).
    */
   @informative
-  int libraryNameOffset;
+  int get libraryNameOffset;
 
   /**
    * Length of the library name as it appears in the source code (or 0 if the
    * library has no name).
    */
   @informative
-  int libraryNameLength;
+  int get libraryNameLength;
 
   /**
    * Documentation comment for the library, or `null` if there is no
    * documentation comment.
    */
   @informative
-  UnlinkedDocumentationComment libraryDocumentationComment;
+  UnlinkedDocumentationComment get libraryDocumentationComment;
 
   /**
    * Unlinked public namespace of this compilation unit.
    */
-  UnlinkedPublicNamespace publicNamespace;
+  UnlinkedPublicNamespace get publicNamespace;
 
   /**
    * Top level and prefixed names referred to by this compilation unit.  The
    * zeroth element of this array is always populated and is used to represent
    * the absence of a reference in places where a reference is optional (for
    * example [UnlinkedReference.prefixReference or
    * UnlinkedImport.prefixReference]).
    */
-  List<UnlinkedReference> references;
+  List<UnlinkedReference> get references;
 
   /**
    * Classes declared in the compilation unit.
    */
-  List<UnlinkedClass> classes;
+  List<UnlinkedClass> get classes;
 
   /**
    * Enums declared in the compilation unit.
    */
-  List<UnlinkedEnum> enums;
+  List<UnlinkedEnum> get enums;
 
   /**
    * Top level executable objects (functions, getters, and setters) declared in
    * the compilation unit.
    */
-  List<UnlinkedExecutable> executables;
+  List<UnlinkedExecutable> get executables;
 
   /**
    * Export declarations in the compilation unit.
    */
-  List<UnlinkedExportNonPublic> exports;
+  List<UnlinkedExportNonPublic> get exports;
 
   /**
    * Import declarations in the compilation unit.
    */
-  List<UnlinkedImport> imports;
+  List<UnlinkedImport> get imports;
 
   /**
    * Part declarations in the compilation unit.
    */
-  List<UnlinkedPart> parts;
+  List<UnlinkedPart> get parts;
 
   /**
    * Typedefs declared in the compilation unit.
    */
-  List<UnlinkedTypedef> typedefs;
+  List<UnlinkedTypedef> get typedefs;
 
   /**
    * Top level variables declared in the compilation unit.
    */
-  List<UnlinkedVariable> variables;
+  List<UnlinkedVariable> get variables;
 }
 
 /**
  * Unlinked summary information about a top level variable, local variable, or
  * a field.
  */
-class UnlinkedVariable {
+abstract class UnlinkedVariable extends base.SummaryClass {
   /**
    * Name of the variable.
    */
-  String name;
+  String get name;
 
   /**
    * Offset of the variable name relative to the beginning of the file.
    */
   @informative
-  int nameOffset;
+  int get nameOffset;
 
   /**
    * Documentation comment for the variable, or `null` if there is no
    * documentation comment.
    */
   @informative
-  UnlinkedDocumentationComment documentationComment;
+  UnlinkedDocumentationComment get documentationComment;
 
   /**
    * Declared type of the variable.  Absent if the type is implicit.
    */
-  EntityRef type;
+  EntityRef get type;
 
   /**
    * If [isConst] is true, and the variable has an initializer, the constant
    * expression in the initializer.
    */
-  UnlinkedConst constExpr;
+  UnlinkedConst get constExpr;
 
   /**
    * Indicates whether the variable is declared using the `static` keyword.
    *
    * Note that for top level variables, this flag is false, since they are not
    * declared using the `static` keyword (even though they are considered
    * static for semantic purposes).
    */
-  bool isStatic;
+  bool get isStatic;
 
   /**
    * Indicates whether the variable is declared using the `final` keyword.
    */
-  bool isFinal;
+  bool get isFinal;
 
   /**
    * Indicates whether the variable is declared using the `const` keyword.
    */
-  bool isConst;
+  bool get isConst;
 
   /**
    * If this variable is propagable, nonzero slot id identifying which entry in
    * [LinkedLibrary.types] contains the propagated type for this variable.  If
    * there is no matching entry in [LinkedLibrary.types], then this variable's
    * propagated type is the same as its declared type.
    *
    * Non-propagable variables have a [propagatedTypeSlot] of zero.
    */
-  int propagatedTypeSlot;
+  int get propagatedTypeSlot;
 
   /**
    * If this variable is inferrable, nonzero slot id identifying which entry in
    * [LinkedLibrary.types] contains the inferred type for this variable.  If
    * there is no matching entry in [LinkedLibrary.types], then no type was
    * inferred for this variable, so its static type is `dynamic`.
    */
-  int inferredTypeSlot;
+  int get inferredTypeSlot;
 }