Add fasta-based summary generation code.

pkg/analyzer/lib/src/summary/fasta/summary_builder.dart

Index: pkg/analyzer/lib/src/summary/fasta/summary_builder.dart
diff --git a/pkg/analyzer/lib/src/summary/fasta/summary_builder.dart b/pkg/analyzer/lib/src/summary/fasta/summary_builder.dart
new file mode 100644
index 0000000000000000000000000000000000000000..788238b01b9f0132fe160b9194819aaec247ba3b
--- /dev/null
+++ b/pkg/analyzer/lib/src/summary/fasta/summary_builder.dart
@@ -0,0 +1,1573 @@
+// Copyright (c) 2017, 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.
+
+/// Logic to build unlinked summaries.
+library summary.src.summary_builder;
+
+import 'expression_serializer.dart';
+import 'model.dart';
+import 'package:front_end/src/fasta/parser/class_member_parser.dart';

[Siggi Cherem (dart-lang), 2017/03/09 21:02:14]

I'm surprised that the sorting of imports doesn't respect the split between
local and package-imports.

I personally prefer to have that split, but we can keep it if that's hard to
change.

[Paul Berry, 2017/03/09 23:26:23]

Oops--I added these imports in any old location because I was intending to use
analysis server's "sort" function on the file later and fix it up.  I forgot to
sort them afterwards.

I'll sort before landing the CL.

+import 'package:front_end/src/fasta/parser/identifier_context.dart';
+import 'package:front_end/src/fasta/parser/parser.dart';
+import 'package:front_end/src/fasta/scanner.dart';
+import 'package:front_end/src/fasta/scanner/token_constants.dart';
+import 'stack_listener.dart';
+
+/// Create an unlinked summary given a null-terminated byte buffer with the
+/// contents of a file.
+UnlinkedUnit summarize(Uri uri, List<int> contents) {
+  var listener = new SummaryBuilder(uri);
+  var parser = new ClassMemberParser(listener);
+  parser.parseUnit(scan(contents).tokens);
+  return listener.topScope.unit;
+}
+
+/// A listener of parser events that builds summary information as parsing
+/// progresses.
+class SummaryBuilder extends StackListener {
+  /// Whether 'dart:core' was imported explicitly by the current unit.
+  bool isDartCoreImported = false;
+
+  /// Whether the current unit is part of 'dart:core'.
+  bool isCoreLibrary = false;
+
+  /// Topmost scope.
+  TopScope topScope;
+
+  /// Current scope where name references are resolved from.
+  Scope scope;
+
+  /// Helper to build constant expressions.
+  final ConstExpressionBuilder constBuilder;
+
+  /// Helper to build initializer expressions.
+  final InitializerBuilder initializerBuilder;
+
+  /// Whether the current initializer has a type declared.
+  ///
+  /// Because initializers are only used for strong-mode inference, we can skip
+  /// parsing and building initializer expressions when a type is declared.
+  bool typeSeen = false;
+
+  /// Whether we are currently in the context of a const expression.
+  bool inConstContext = false;
+
+  /// Whether we need to parse the initializer of a declaration.
+  bool get needInitializer => !typeSeen || inConstContext;
+
+  /// Uri of the file currently being processed, used for error reporting only.
+  final Uri uri;
+
+
+  /// Summaries preassign slots for computed information, this is the next
+  /// available slot.
+  int _slots = 0;
+
+  SummaryBuilder(Uri uri)
+      : uri = uri,
+        constBuilder = new ConstExpressionBuilder(uri),
+        initializerBuilder = new InitializerBuilder(uri);
+
+  void handleNoConstructorReferenceContinuationAfterTypeArguments(Token token) {
+    debugEvent("NoConstructorReferenceContinuationAfterTypeArguments");
+  }
+
+  void beginCompilationUnit(Token token) {
+    scope = topScope = new TopScope();
+  }
+
+  void endCompilationUnit(int count, Token token) {
+    if (!isDartCoreImported) {
+      topScope.unit.imports.add(new UnlinkedImportBuilder(isImplicit: true));
+    }
+
+    topScope.expandLazyReferences();
+
+    // TODO(sigmund): could this be be optional: done by whoever consumes it?
+    if (const bool.fromEnvironment('SKIP_API')) return;
+    var apiSignature = new ApiSignature();
+    topScope.unit.collectApiSignature(apiSignature);
+    topScope.unit.apiSignature = apiSignature.toByteList();
+  }
+
+  // Directives: imports, exports, parts
+
+  void endHide(_) {
+    // ignore: strong_mode_down_cast_composite
+    push(new UnlinkedCombinatorBuilder(hides: pop()));
+  }
+
+  void endShow(_) {
+    // ignore: strong_mode_down_cast_composite
+    push(new UnlinkedCombinatorBuilder(shows: pop()));
+  }
+
+  void endCombinators(int count) {
+    debugEvent("Combinators");
+    push(popList(count) ?? NullValue.Combinators);
+  }
+
+  void endConditionalUri(Token ifKeyword, Token equalitySign) {
+    String dottedName = pop();
+    String value = pop();
+    String uri = pop();
+    uri = uri.substring(1, uri.length - 1);
+    push(new UnlinkedConfigurationBuilder(
+        name: dottedName, value: value, uri: uri));
+  }
+
+  void endConditionalUris(int count) {
+    push(popList(count) ?? const <UnlinkedConfigurationBuilder>[]);
+  }
+
+  void endExport(Token exportKeyword, Token semicolon) {
+    debugEvent("Export");
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedCombinator> combinators = pop();
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedConfiguration> conditionalUris = pop();
+    String uri = pop();
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedExpr> metadata = pop();
+    topScope.unit.exports.add(new UnlinkedExportNonPublicBuilder(annotations: metadata));
+    topScope.publicNamespace.exports.add(new UnlinkedExportPublicBuilder(
+        uri: uri,
+        combinators: combinators,
+        configurations: conditionalUris));
+    checkEmpty();
+  }
+
+  void endImport(Token importKeyword, Token deferredKeyword, Token asKeyword,
+      Token semicolon) {
+    debugEvent("endImport");
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedCombinator> combinators = pop();
+    String prefix = popIfNotNull(asKeyword);
+    int prefixIndex = prefix == null ? null
+      : topScope.serializeReference(null, prefix);
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedConfiguration> conditionalUris = pop();
+    String uri = pop();
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedExpr> metadata = pop(); // metadata
+
+    topScope.unit.imports.add(new UnlinkedImportBuilder(
+          uri: uri,
+          prefixReference: prefixIndex,
+          combinators: combinators,
+          configurations: conditionalUris,
+          isDeferred: deferredKeyword != null,
+          annotations: metadata,
+    ));
+    if (uri == 'dart:core') isDartCoreImported = true;
+    checkEmpty();
+  }
+
+  void endPart(Token partKeyword, Token semicolon) {
+    debugEvent("Part");
+    String uri = pop();
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedExpr> metadata = pop();
+    topScope.unit.parts.add(new UnlinkedPartBuilder(annotations: metadata));
+    topScope.publicNamespace.parts.add(uri);
+    checkEmpty();
+  }
+
+  void endLibraryName(Token libraryKeyword, Token semicolon) {
+    debugEvent("endLibraryName");
+    String name = pop();
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedExpr> metadata = pop(); // metadata
+
+    topScope.unit.libraryName = name;
+    topScope.unit.libraryAnnotations = metadata;
+    if (name == 'dart.core') isCoreLibrary = true;
+  }
+
+  void endPartOf(Token partKeyword, Token semicolon) {
+    debugEvent("endPartOf");
+    String name = pop();
+    pop(); // metadata
+    topScope.unit.isPartOf = true;
+    if (name == 'dart.core') isCoreLibrary = true;
+  }
+
+  // classes, enums, mixins, and typedefs.
+
+  void beginClassDeclaration(Token beginToken, Token name) {
+    debugEvent("beginClass");
+    var classScope = scope = new ClassScope(scope);
+    classScope.className = name.value;
+  }
+
+  void endClassBody(int memberCount, Token beginToken, Token endToken) {
+    debugEvent("ClassBody");
+  }
+
+  void endClassDeclaration(int interfacesCount, Token beginToken, Token classKeyword,
+      Token extendsKeyword, Token implementsKeyword, Token endToken) {
+    debugEvent("endClassDeclaration");
+    // ignore: strong_mode_down_cast_composite
+    List<EntityRefBuilder> interfaces = popList(interfacesCount);
+    EntityRef supertype = pop();
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedTypeParamBuilder> typeVariables = pop();
+    String name = pop();
+    int modifiers = pop();
+    List metadata = pop();
+    checkEmpty();
+
+    ClassScope s = scope;
+    s.className = name;
+    s.currentClass
+      ..name = name
+      ..isAbstract = modifiers & _abstract_flag != 0
+      // ignore: strong_mode_down_cast_composite
+      ..annotations = metadata
+      ..typeParameters = typeVariables
+      ..interfaces = interfaces;
+    if (supertype != null) {
+      s.currentClass.supertype = supertype;
+    } else {
+      s.currentClass.hasNoSupertype = isCoreLibrary && name == 'Object';
+    }
+    scope = scope.parent;
+    topScope.unit.classes.add(s.currentClass);
+    if (_isPrivate(name)) return;
+    s.publicName
+        ..name = name
+        ..kind = ReferenceKind.classOrEnum
+        ..numTypeParameters = typeVariables?.length;
+    topScope.publicNamespace.names.add(s.publicName);
+  }
+
+  void beginEnum(Token token) {
+    debugEvent("beginEnum");
+    scope = new EnumScope(scope);
+  }
+
+  void endEnum(Token enumKeyword, Token endBrace, int count) {
+    debugEvent("Enum");
+    // ignore: strong_mode_down_cast_composite
+    List<String> constants = popList(count);
+    String name = pop();
+    List metadata = pop();
+    checkEmpty();
+    EnumScope s = scope;
+    scope = s.parent;
+    s.currentEnum
+      ..name = name
+      // ignore: strong_mode_down_cast_composite
+      ..annotations = metadata;
+    s.top.unit.enums.add(s.currentEnum);
+
+    // public namespace:
+    var e = new UnlinkedPublicNameBuilder(
+        name: name,
+        kind: ReferenceKind.classOrEnum,
+        numTypeParameters: 0);
+    for (var s in constants) {
+      e.members.add(new UnlinkedPublicNameBuilder(
+            name: s,
+            kind: ReferenceKind.propertyAccessor,
+            numTypeParameters: 0));
+    }
+    topScope.publicNamespace.names.add(e);
+  }
+
+  void endMixinApplication(Token withKeyword) {
+    debugEvent("MixinApplication");
+    ClassScope s = scope;
+    // ignore: strong_mode_down_cast_composite
+    s.currentClass.mixins = pop();
+  }
+
+  void beginNamedMixinApplication(Token beginToken, Token name) {
+    debugEvent('beginNamedMixinApplication');
+    scope = new ClassScope(scope);
+  }
+
+  void endNamedMixinApplication(
+      Token begin, Token classKeyword, Token equals,
+      Token implementsKeyword, Token endToken) {
+    debugEvent("endNamedMixinApplication");
+    // ignore: strong_mode_down_cast_composite
+    List<EntityRef> interfaces = popIfNotNull(implementsKeyword);
+    EntityRef supertype = pop();
+    List typeVariables = pop();
+    String name = pop();
+    int modifiers = pop();
+    List metadata = pop();
+    // print('TODO: end mix, $name');
+    checkEmpty();
+
+    ClassScope s = scope;
+    s.currentClass
+      ..name = name
+      ..isAbstract = modifiers & _abstract_flag != 0
+      ..isMixinApplication = true
+      // ignore: strong_mode_down_cast_composite
+      ..annotations = metadata
+      // ignore: strong_mode_down_cast_composite
+      ..typeParameters = typeVariables
+      ..interfaces = interfaces;
+    if (supertype != null) {
+      s.currentClass.supertype = supertype;
+    } else {
+      s.currentClass.hasNoSupertype = isCoreLibrary && name == 'Object';
+    }
+    scope = scope.parent;
+    topScope.unit.classes.add(s.currentClass);
+
+    _addNameIfPublic(name, ReferenceKind.classOrEnum, typeVariables.length);
+  }
+
+  void beginFunctionTypeAlias(Token token) {
+    debugEvent('beginFunctionTypeAlias');
+    // TODO: use a single scope
+    scope = new TypeParameterScope(scope);
+  }
+
+  void endFunctionTypeAlias(Token typedefKeyword, Token equals, Token endToken) {
+    debugEvent("endFunctionTypeAlias");
+    List formals = pop();
+    List typeVariables = pop();
+    String name = pop();
+    EntityRef returnType = pop();
+    List metadata = pop();
+    // print('TODO: type alias $name');
+    checkEmpty();
+
+    scope = scope.parent;
+    topScope.unit.typedefs.add(new UnlinkedTypedefBuilder(
+        name: name,
+        // ignore: strong_mode_down_cast_composite
+        typeParameters: typeVariables,
+        returnType: returnType,
+        // ignore: strong_mode_down_cast_composite
+        parameters: formals,
+        // ignore: strong_mode_down_cast_composite
+        annotations: metadata));
+
+    _addNameIfPublic(name, ReferenceKind.typedef, typeVariables.length);
+  }
+
+  // members: fields, methods.
+
+  void beginTopLevelMember(Token token) {
+    typeSeen = false;
+    inConstContext = false;
+  }
+
+  void beginMember(Token token) {
+    typeSeen = false;
+    inConstContext = false;
+  }
+
+  void endMember() {
+    debugEvent("Member");
+  }
+
+  void handleType(Token beginToken, Token endToken) {
+    debugEvent("Type");
+    // ignore: strong_mode_down_cast_composite
+    List<EntityRef> arguments = pop();
+    String name = pop();
+
+    var type;
+    if (name.contains('.')) {
+      var parts = name.split('.');
+      for (var p in parts) {
+        type = type == null
+            ? new LazyEntityRef(p, scope)
+            : new NestedLazyEntityRef(type, p, scope);
+      }
+    } else {
+      type = new LazyEntityRef(name, scope);
+    }
+    type.typeArguments = arguments;
+    push(type);
+    typeSeen = true;
+  }
+
+  void endTypeList(int count) {
+    debugEvent("TypeList");
+    push(popList(count) ?? NullValue.TypeList);
+  }
+
+  static int parsed = 0;
+  static int total = 0;
+  beginInitializer(Token token) {
+    // TODO(paulberry): Add support for this.
+  }
+
+  beginFieldInitializer(Token token) {
+    // TODO(paulberry): Copied from beginFieldInitializer.  Is all of this needed?

[Siggi Cherem (dart-lang), 2017/03/09 21:02:13]

did you mean from beginInitializer?

[Paul Berry, 2017/03/09 23:26:23]

Oops, yes.  I've removed this TODO--it was a placeholder I put in before I
understood the difference between beginInitializer and beginFieldInitializer.

+    debugEvent("beginFieldInitializer");
+    total++;
+    if (needInitializer) {
+      parsed++;
+      if (inConstContext) {
+        push(constBuilder.computeExpression(token.next, scope));
+      } else {
+        push(initializerBuilder.computeExpression(token.next, scope));
+      }
+    }
+  }
+
+  void endInitializer(Token assignmentOperator) {
+    // TODO(paulberry): add support for this.
+    debugEvent("Initializer $typeSeen $assignmentOperator");
+  }
+
+  void endFieldInitializer(Token assignmentOperator) {
+    // TODO(paulberry): copied from endInitializer.  Is all of this needed?

[Siggi Cherem (dart-lang), 2017/03/09 21:02:14]

just to make sure I follow - you are wondering if we can simplify how we handle
the initializer expressions or something else?

[Paul Berry, 2017/03/09 23:26:23]

At the time I wrote the TODO I didn't understand the difference between
endInitializer and endFieldInitializer, so I wasn't sure which function the code
belonged in.  Later when I figured out that it *does* belong here, I forgot to
remove the TODO.

I've removed it now.

+    debugEvent("FieldInitializer $typeSeen $assignmentOperator");
+    // This is a variable initializer and it's ignored for now. May also be
+    // constructor initializer.
+    var initializer = needInitializer && assignmentOperator != null
+        ? pop() : null;
+    var name = pop();
+    push(new _InitializedName(name, new UnlinkedExecutableBuilder(
+        bodyExpr: initializer)));
+  }
+
+  void endTopLevelFields(int count, Token beginToken, Token endToken) {
+    debugEvent("endTopLevelFields");
+    _endFields(count, topScope.unit.variables, true);
+    checkEmpty();
+  }
+
+  void endFields(int count, Token covariantKeyword, Token beginToken, Token endToken) {
+    debugEvent("Fields");
+    var s = scope;
+    if (s is ClassScope) {
+      _endFields(count, s.currentClass.fields, false);
+    } else {
+      throw new UnimplementedError(); // TODO(paulberry): does this ever occur?

[Siggi Cherem (dart-lang), 2017/03/09 21:02:14]

do you mean that we don't summarize enums altogether?

[Paul Berry, 2017/03/09 23:26:23]

We do summarize enums, but the parsing of enums never calls "endFields".  So I
believe thes code is unreachable.

+      // _endFields(count, s.currentEnum.values, false);
+    }
+  }
+
+  void _endFields(int count, List result, bool isTopLevel) {
+    debugEvent('EndFields: $count $isTopLevel');
+    // ignore: strong_mode_down_cast_composite
+    List<_InitializedName> fields = popList(count);
+    EntityRef type = pop();
+    int modifiers = pop();
+    List metadata = pop();
+
+    bool isStatic = modifiers & _static_flag != 0;
+    bool isFinal = modifiers & _final_flag != 0;
+    bool isConst = modifiers & _const_flag != 0;
+    bool isInstance = !isStatic && !isTopLevel;
+    for (var field in fields) {
+      var name = field.name;
+      var initializer = field.initializer;
+      bool needsPropagatedType = initializer != null && (isFinal || isConst);
+      bool needsInferredType =
+          type == null && (initializer != null || isInstance);
+      result.add(new UnlinkedVariableBuilder(
+        isFinal: isFinal,
+        isConst: isConst,
+        isStatic: isStatic,
+        name: name,
+        type: type,
+        // ignore: strong_mode_down_cast_composite
+        annotations: metadata,
+        initializer: initializer,
+        propagatedTypeSlot: slotIf(needsPropagatedType),
+        inferredTypeSlot: slotIf(needsInferredType)));
+
+      if (_isPrivate(name)) continue;
+      if (isTopLevel) {
+        _addPropertyName(name, includeSetter: !isFinal && !isConst);
+      } else if (isStatic) {
+        // Any reason setters are not added as well?
+        (scope as ClassScope).publicName.members.add(new UnlinkedPublicNameBuilder(
+              name: name,
+              kind: ReferenceKind.propertyAccessor,
+              numTypeParameters: 0));
+      }
+    }
+  }
+
+
+  void endTopLevelMethod(
+      Token beginToken, Token getOrSet, Token endToken) {
+    debugEvent("endTopLevelMethod");
+    int asyncModifier = pop();
+    List formals = pop();
+    List typeVariables = pop();
+    String name = pop();
+    EntityRef returnType = pop();
+    int modifiers = pop();
+    List metadata = pop();
+    checkEmpty();
+
+    topScope.unit.executables.add(new UnlinkedExecutableBuilder(
+          name: getOrSet == 'set' ? '$name=' : name,
+          kind: getOrSet == 'get'
+              ? UnlinkedExecutableKind.getter
+              : (getOrSet == 'set' ?  UnlinkedExecutableKind.setter
+                  : UnlinkedExecutableKind.functionOrMethod),
+          isExternal: modifiers & _external_flag != 0,
+          isAbstract: modifiers & _abstract_flag != 0,
+          isAsynchronous: asyncModifier & _async_flag != 0,
+          isGenerator: asyncModifier & _star_flag != 0,
+          isStatic: modifiers & _static_flag != 0,
+          typeParameters: [], // TODO
+          returnType: returnType,
+          // ignore: strong_mode_down_cast_composite
+          parameters: formals,
+          // ignore: strong_mode_down_cast_composite
+          annotations: metadata,
+          inferredReturnTypeSlot: null, // not needed for top-levels
+          // skip body.
+          ));
+
+    String normalizedName = getOrSet == 'set' ? '$name=' : name;
+    _addNameIfPublic(
+        normalizedName,
+        getOrSet != null ? ReferenceKind.topLevelPropertyAccessor : ReferenceKind.topLevelFunction,
+        typeVariables?.length ?? 0 /* todo */);
+  }
+
+  void endMethod(Token getOrSet, Token beginToken, Token endToken) {
+    debugEvent("Method");
+    int asyncModifier = pop();
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedParam> formals = pop();
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedTypeParamBuilder> typeVariables = pop();
+    String name = pop();
+    EntityRef returnType = pop();
+    int modifiers = pop();
+    List metadata = pop();
+
+    ClassScope s = scope;
+    bool isStatic = modifiers & _static_flag != 0;
+    bool isConst = modifiers & _const_flag != 0;
+    bool isGetter = getOrSet == 'get';
+    bool isSetter = getOrSet == 'set';
+    bool isOperator = name == "operator"; // TODO
+    bool isConstructor =
+        name == s.className || name.startsWith('${s.className}.');
+
+    if (isConstructor) {
+      name = name == s.className ? '' : name.substring(name.indexOf('.') + 1);
+    }
+
+    name = isSetter ? '$name=' : name;
+    // Note: we don't include bodies for any method.
+    s.currentClass.executables.add(new UnlinkedExecutableBuilder(
+          name: name,
+          kind: isGetter
+            ? UnlinkedExecutableKind.getter
+            : (isSetter
+                ? UnlinkedExecutableKind.setter
+                : (isConstructor
+                    ? UnlinkedExecutableKind.constructor
+                    : UnlinkedExecutableKind.functionOrMethod)),
+          isExternal: modifiers & _external_flag != 0,
+          isAbstract: modifiers & _abstract_flag != 0,
+          isAsynchronous: asyncModifier & _async_flag != 0,
+          isGenerator: asyncModifier & _star_flag != 0,
+          isStatic: isStatic,
+          isConst: isConst,
+          constCycleSlot: slotIf(isConst),
+          typeParameters: typeVariables,
+          returnType: returnType,
+          parameters: formals, // TODO: add inferred slot to args
+          // ignore: strong_mode_down_cast_composite
+          annotations: metadata,
+          inferredReturnTypeSlot: slotIf(returnType == null && !isStatic &&
+              !isConstructor)));
+
+    if (isConstructor && name == '') return;
+    if (_isPrivate(name)) return;
+    if (isSetter || isOperator) return;
+    if (!isStatic && !isConstructor) return;
+    s.publicName.members.add(new UnlinkedPublicNameBuilder(
+          name: name,
+          kind: isGetter ? ReferenceKind.propertyAccessor :
+              (isConstructor ? ReferenceKind.constructor :
+              ReferenceKind.method),
+          numTypeParameters: typeVariables.length));
+  }
+
+  void endTypeArguments(int count, Token beginToken, Token endToken) {
+    debugEvent("TypeArguments");
+    push(popList(count) ?? const []);
+  }
+
+
+  void handleVoidKeyword(Token token) {
+    debugEvent("VoidKeyword");
+    // TODO: skip the lazy mechanism
+    push(new LazyEntityRef("void", scope.top));
+  }
+
+  void endFormalParameter(Token covariantKeyword, Token thisKeyword, FormalParameterType kind) {
+    debugEvent("FormalParameter");
+    // TODO(sigmund): clean up?
+    var nameOrFormal = pop();
+    if (nameOrFormal is String) {
+      EntityRef type = pop();
+      pop(); // Modifiers
+      List metadata = pop();
+      push(new UnlinkedParamBuilder(
+            name: nameOrFormal,
+            kind: _nextParamKind,
+            inheritsCovariantSlot: slotIf(type == null),
+            // ignore: strong_mode_down_cast_composite
+            annotations: metadata,
+            isInitializingFormal: thisKeyword != null,
+            type: type));
+    } else {
+      push(nameOrFormal);
+    }
+  }
+
+  // TODO(sigmund): handle metadata (this code is incomplete).
+  void endMetadata(Token beginToken, Token periodBeforeName, Token endToken) {
+    debugEvent("Metadata");
+    List arguments = pop();
+    var result = new UnlinkedExprBuilder();
+    // If arguments are null, this is an expression, otherwise a constructor
+    // reference.
+    if (arguments == null) {
+      /* String postfix = */ popIfNotNull(periodBeforeName);
+      /* String expression = */ pop();
+      //push([expression, postfix]); // @x or @p.x
+    } else {
+      /* String name = */ popIfNotNull(periodBeforeName);
+      // TODO(ahe): Type arguments are missing, eventually they should be
+      // available as part of [arguments].
+      // List<String> typeArguments = null;
+      /* EntityRef typeName = */ pop();
+      //push([typeName, typeArguments, name, arguments]);
+    }
+    push(result);
+  }
+
+  void endMetadataStar(int count, bool forParameter) {
+    debugEvent("MetadataStar");
+    push(popList(count) ?? NullValue.Metadata);
+  }
+
+  void handleStringPart(token) {
+    debugEvent("handleStringPart");
+    push(token.value.substring(1, token.value.length - 1));
+  }
+
+  void beginLiteralString(Token token) {
+    debugEvent("beginLiteralString");
+    push(token.value.substring(1, token.value.length - 1));
+  }
+
+  void endLiteralString(int count) {
+    assert(count == 0); // TODO(sigmund): handle interpolation
+  }
+
+  void handleQualified(Token period) {
+    debugEvent("handleQualified");
+    String name = pop();
+    String receiver = pop();
+    push("$receiver.$name");
+  }
+
+  void endDottedName(count, firstIdentifier) {
+    push(popList(count).join('.'));
+  }
+
+  void handleOperatorName(Token operatorKeyword, Token token) {
+    // TODO(sigmund): convert operator names to name used by summaries.
+    debugEvent("OperatorName");
+    push(operatorKeyword.value);
+  }
+
+  void endIdentifierList(int count) {
+    debugEvent("endIdentifierList");
+    push(popList(count) ?? NullValue.IdentifierList);
+  }
+
+  void handleModifier(Token token) {
+    debugEvent("Modifier");
+    var modifier = _modifierFlag[token.stringValue];
+    if (modifier & _const_flag != 0) inConstContext = true;
+    push(modifier);
+  }
+
+  void handleModifiers(int count) {
+    debugEvent("Modifiers");
+    push((popList(count) ?? const []).fold(0, (a, b) => a | b));
+  }
+
+  UnlinkedParamKind _nextParamKind;
+  void beginFormalParameters(Token begin) {
+    _nextParamKind = UnlinkedParamKind.required;
+  }
+  void beginOptionalFormalParameters(Token begin) {
+    _nextParamKind =
+        begin == '{' ? UnlinkedParamKind.named : UnlinkedParamKind.positional;
+  }
+
+  void handleValuedFormalParameter(Token equals, Token token) {
+    debugEvent("ValuedFormalParameter");
+    // TODO(sigmund): include default value on optional args.
+  }
+
+  void endFunctionTypedFormalParameter(Token covariantKeyword, Token thisKeyword, FormalParameterType kind) {
+    debugEvent("FunctionTypedFormalParameter");
+    // ignore: strong_mode_down_cast_composite
+    List<UnlinkedParamBuilder> formals = pop();
+    if (formals != null) formals.forEach((p) => p.inheritsCovariantSlot = null);
+
+    /* List typeVariables = */ pop();
+    String name = pop();
+    EntityRef returnType = pop();
+    /* int modifiers = */ pop();
+    List metadata = pop();
+
+    push(new UnlinkedParamBuilder(
+          name: name,
+          kind: _nextParamKind,
+          isFunctionTyped: true,
+          parameters: formals,
+          // ignore: strong_mode_down_cast_composite
+          annotations: metadata,
+          type: returnType));
+  }
+
+  void endOptionalFormalParameters(
+      int count, Token beginToken, Token endToken) {
+    debugEvent("OptionalFormalParameters");
+    push(popList(count));
+  }
+
+  void endFormalParameters(int count, Token beginToken, Token endToken) {
+    debugEvent("FormalParameters");
+    List formals = popList(count);
+    if (formals != null && formals.isNotEmpty) {
+      var last = formals.last;
+      if (last is List) {
+        var newList = new List(formals.length - 1 + last.length);
+        newList.setRange(0, formals.length - 1, formals);
+        newList.setRange(formals.length - 1, newList.length, last);
+        for (int i = 0; i < last.length; i++) {
+          newList[i + formals.length - 1] = last[i];
+        }
+        formals = newList;
+      }
+    }
+    push(formals ?? NullValue.FormalParameters);
+  }
+
+  void endTypeVariables(int count, Token beginToken, Token endToken) {
+    debugEvent("TypeVariables");
+    push(popList(count) ?? const []);
+  }
+
+  void endTypeVariable(Token token, Token extendsOrSuper) {
+    debugEvent("endTypeVariable");
+    EntityRef bound = pop();
+    String name = pop();
+
+    var s = scope;
+    if (s is TypeParameterScope) {
+      s.typeParameters.add(name);
+    } else {
+      throw new UnimplementedError(); // TODO(paulberry)
+    }
+    push(new UnlinkedTypeParamBuilder(
+        name: name,
+        bound: bound));
+  }
+
+  void endFactoryMethod(Token beginToken, Token endToken) {
+    debugEvent("FactoryMethod");
+    throw new UnimplementedError(); // TODO(paulberry)
+    // pop(); // async-modifiers
+    // /* List<FormalParameterBuilder> formals = */ pop();
+    // var name = pop();
+    // /* List<MetadataBuilder> metadata = */ pop();
+  }
+
+
+  void endRedirectingFactoryBody(Token beginToken, Token endToken) {
+    debugEvent("RedirectingFactoryBody");
+    pop(); // Discard ConstructorReferenceBuilder.
+  }
+
+  void endConstructorReference(
+      Token start, Token periodBeforeName, Token endToken) {
+    var ctorName = popIfNotNull(periodBeforeName);
+    var typeArguments = pop();
+    var className = pop();
+    push(['ctor-ref:', className, typeArguments, ctorName]);
+  }
+
+  void endInitializers(int count, Token beginToken, Token endToken) {
+    debugEvent("Initializers");
+    // TODO(sigmund): include const-constructor initializers
+  }
+
+  void handleNoFieldInitializer(Token token) {
+    debugEvent("NoFieldInitializer");
+    push(new _InitializedName(pop(), null));
+  }
+
+  void handleNoTypeVariables(Token token) {
+    debugEvent("NoTypeVariables");
+    push(const []);
+  }
+
+  void handleNoInitializers() {
+    debugEvent("NoInitializers");
+    // This is a constructor initializer and it's ignored for now.
+  }
+
+  void handleNoFunctionBody(Token token) {
+    debugEvent("NoFunctionBody");
+    // Ignored for now. We shouldn't see any function bodies.
+  }
+
+  void handleAsyncModifier(Token asyncToken, Token starToken) {
+    debugEvent("AsyncModifier");
+    int asyncModifier = 0;
+    if (asyncToken == "async") asyncModifier |= _async_flag;
+    if (asyncToken == "sync") asyncModifier |= _sync_flag;
+    if (starToken != null) asyncModifier |= _star_flag;
+    push(asyncModifier);
+  }
+
+  // helpers to work with the summary format.
+
+
+  /// Assign the next slot.
+  int assignSlot() => ++_slots;
+
+  /// Assign the next slot if [condition] is true.
+  int slotIf(bool condition) => condition ? assignSlot() : 0;
+
+  /// Whether a name is private and should be excluded from the public
+  /// namespace.
+  bool _isPrivate(String name) => name.startsWith('_');
+
+  /// Add [name] to the public namespace if it's public.
+  void _addNameIfPublic(
+      String name, ReferenceKind kind, int numTypeParameters) {
+    if (_isPrivate(name)) return null;
+    _addName(name, kind, numTypeParameters: numTypeParameters);
+  }
+
+  /// Add [name] to the public namespace.
+  void _addName(
+      String name, ReferenceKind kind, {int numTypeParameters: 0}) {
+    topScope.publicNamespace.names.add(new UnlinkedPublicNameBuilder(
+        name: name,
+        kind: kind,
+        numTypeParameters: numTypeParameters));
+  }
+
+  /// Add `name` and, if requested, `name=` to the public namespace.
+  void _addPropertyName(String name, {bool includeSetter: false}) {
+    _addName(name, ReferenceKind.topLevelPropertyAccessor);
+    if (includeSetter) {
+      _addName('$name=', ReferenceKind.topLevelPropertyAccessor);
+    }
+  }
+
+  /// If enabled, show a debug message.
+  void debugEvent(String name) {
+    if (const bool.fromEnvironment('DEBUG', defaultValue: false)) {
+      var s = stack.join(' :: ');
+      if (s == '') s = '<empty>';
+      var bits = 'type?: $typeSeen, const?: $inConstContext';
+      var prefix = "do $name on:";
+      prefix = '$prefix${" " * (30 - prefix.length)}';
+      print('$prefix $bits $s');
+    }
+  }
+
+  void handleFormalParameterWithoutValue(Token token) {
+    debugEvent("FormalParameterWithoutValue");
+  }
+}
+
+/// Internal representation of an initialized name.
+class _InitializedName {
+  final String name;
+  final UnlinkedExecutableBuilder initializer;
+  _InitializedName(this.name, this.initializer);
+
+  toString() => "II:" + (initializer != null ? "$name = $initializer" : name);
+}
+
+/// Parser listener to build simplified AST expresions.
+///
+/// The parser produces different trees depending on whether it is used for
+/// constants or initializers, so subclasses specialize the logic accordingly.
+abstract class ExpressionListener extends StackListener {
+  // Underlying parser that invokes this listener.
+  Parser get parser;
+
+  /// Whether to ignore the next reduction. Used to ignore nested expresions
+  /// that are either invalid (in constants) or unnecessary (for initializers).
+  bool get ignore => _withinFunction > 0 || _withinCascades > 0;
+
+  /// Whether this listener is used to build const expressions.
+  bool get forConst => false;
+
+  void push(Object o);
+
+  UnlinkedExprBuilder computeExpression(Token token, Scope scope) {
+    debugStart(token);
+    parser.parseExpression(token);
+    debugEvent('---- END ---');
+    Expression node = pop();
+    checkEmpty();
+    return new Serializer(scope, forConst).run(node);
+  }
+
+  void handleNoInitializer() {}
+
+  void handleIdentifier(Token token, IdentifierContext context) {
+    debugEvent("Identifier");
+    if (ignore) return;
+    push(new Ref(token.value));
+  }
+
+
+  void endFormalParameter(Token covariantKeyword, Token thisKeyword, FormalParameterType kind) {
+    debugEvent("FormalParameter");
+    assert(ignore);
+  }
+
+  void endFunctionBody(int count, Token begin, Token end) {
+    debugEvent("FunctionBody");
+    assert(ignore);
+  }
+
+  void endFunctionName(Token token) {
+    debugEvent("FunctionName");
+    assert(ignore);
+  }
+
+  void endFormalParameters(int c, begin, end) {
+    debugEvent("FormalParameters");
+    assert(ignore);
+  }
+
+  void handleAsyncModifier(Token asyncToken, Token starToken) {
+    debugEvent("AsyncModifier");
+    assert(ignore);
+  }
+
+  void endReturnStatement(hasValue, Token begin, Token end) {
+    debugEvent("ReturnStatement");
+    assert(ignore);
+  }
+
+  void handleStringPart(token) {
+    debugEvent("handleStringPart");
+    if (ignore) return;
+    push(new StringLiteral(token.value));
+  }
+
+  void beginLiteralString(Token token) {
+    debugEvent("beginLiteralString");
+    if (ignore) return;
+    push(new StringLiteral(token.value));
+  }
+
+  void handleStringJuxtaposition(int count) {
+    debugEvent("StringJuxtaposition");
+    if (ignore) return;
+    popList(count);
+    push(new StringLiteral('<juxtapose $count>'));
+  }
+
+  void endLiteralString(int interpolationCount) {
+    debugEvent("endLiteralString");
+    if (interpolationCount != 0) {
+      popList(2 * interpolationCount + 1);
+      push(new StringLiteral("<interpolate $interpolationCount>"));
+    }
+  }
+
+  void endThrowExpression(throwToken, token) {
+    debugEvent("Throw");
+    assert(ignore);
+  }
+
+  void handleNoType(Token token) {
+    debugEvent("NoType");
+    if (ignore) return;
+    push(NullValue.Type);
+  }
+
+  void handleNoFormalParameters(Token token) {
+    debugEvent("NoFormalParameters");
+    assert(ignore);
+  }
+
+  void handleNoArguments(Token token) {
+    debugEvent("NoArguments");
+    if (ignore) return;
+    var typeArguments = pop();
+    assert(typeArguments == null);
+    push(NullValue.Arguments);
+  }
+
+  void handleNoFunctionBody(Token token) {
+    debugEvent("NoFunctionBody");
+    assert(ignore);
+  }
+
+  void handleNoInitializers() {
+    debugEvent("NoInitializers");
+    assert(ignore);
+  }
+
+  void handleNoTypeArguments(Token token) {
+    debugEvent("NoTypeArguments");
+    if (ignore) return;
+    push(NullValue.TypeArguments);
+  }
+
+  // type-arguments are expected to be type references passed to constructors
+  // and generic methods, we need them to model instantiations.
+  void endTypeArguments(int count, Token beginToken, Token endToken) {
+    debugEvent("TypeArguments");
+    if (ignore) return;
+    push(popList(count) ?? const <TypeRef>[]);
+  }
+
+  void handleVoidKeyword(Token token) {
+    debugEvent("VoidKeyword");
+    assert(ignore);
+  }
+
+  void handleType(Token beginToken, Token endToken) {
+    debugEvent("Type");
+    if (ignore) return;
+    // ignore: strong_mode_down_cast_composite
+    List<TypeRef> arguments = pop();
+    Ref name = pop();
+    push(new TypeRef(name, arguments));
+  }
+
+  void endTypeList(int count) {
+    debugEvent("TypeList");
+    push(popList(count) ?? const <TypeRef>[]);
+  }
+
+  void handleBinaryExpression(Token operator) {
+    debugEvent("BinaryExpression");
+    if (ignore) return;
+    Expression right = pop();
+    Expression left = pop();
+    var kind = operator.kind;
+    if (kind == PERIOD_TOKEN) {
+      if (left is Ref && right is Ref && right.prefix == null && left.prefixDepth < 2) {
+        push(new Ref(right.name, left));
+        return;
+      }
+      if (right is Ref) {
+        push(new Load(left, right.name));
+        return;
+      }
+    }
+    push(new Binary(left, right, kind));
+  }
+
+  void handleUnaryPrefixExpression(Token operator) {
+    debugEvent("UnaryPrefix");
+    if (ignore) return;
+    push(new Unary(pop(), operator.kind));
+  }
+
+  void handleLiteralNull(Token token) {
+    debugEvent("LiteralNull");
+    if (ignore) return;
+    push(new NullLiteral());
+  }
+
+  void handleConditionalExpression(Token question, Token colon) {
+    debugEvent("ConditionalExpression");
+    if (ignore) return;
+    var falseBranch = pop();
+    var trueBranch = pop();
+    var cond = pop();
+    push(new Conditional(cond, trueBranch, falseBranch));
+  }
+
+  void handleLiteralInt(Token token) {
+    debugEvent("LiteralInt");
+    if (ignore) return;
+    push(new IntLiteral(int.parse(token.value)));
+  }
+
+  void handleLiteralDouble(Token token) {
+    debugEvent("LiteralDouble");
+    if (ignore) return;
+    push(new DoubleLiteral(double.parse(token.value)));
+  }
+
+  void handleLiteralBool(Token token) {
+    debugEvent("LiteralBool");
+    if (ignore) return;
+    push(new BoolLiteral(token.value == 'true'));
+  }
+
+  void handleIsOperator(Token operator, Token not, Token endToken) {
+    debugEvent("Is");
+    if (ignore) return;
+    push(new Is(pop(), pop()));
+  }
+
+  void handleConstExpression(Token token) {
+    debugEvent("ConstExpression");
+    if (ignore) return;
+    List args = pop();
+    var constructorName = pop();
+    var positional = args.where((a) => a is! NamedArg).toList();
+    var named = args.where((a) => a is NamedArg).toList();
+    // ignore: strong_mode_down_cast_composite
+    push(new ConstCreation(constructorName, positional, named));
+  }
+
+  void handleLiteralList(count, begin, constKeyword, end) {
+    debugEvent("LiteralList");
+    if (ignore) return;
+    var values = popList(count) ?? const <Expression>[];
+    // ignore: strong_mode_down_cast_composite
+    List<TypeRef> typeArguments = pop();
+    var type = typeArguments?.single;
+    // ignore: strong_mode_down_cast_composite
+    push(new ListLiteral(type, values, constKeyword != null));
+  }
+
+  void endLiteralMapEntry(colon, token) {
+    debugEvent('MapEntry');
+    if (ignore) return;
+    var value = pop();
+    var key = pop();
+    push(new KeyValuePair(key, value));
+  }
+
+  void handleLiteralMap(count, begin, constKeyword, end) {
+    debugEvent('LiteralMap');
+    if (ignore) return;
+    var values = popList(count) ?? const <KeyValuePair>[];
+    var typeArgs = pop() ?? const <TypeRef>[];
+    // ignore: strong_mode_down_cast_composite
+    push(new MapLiteral(typeArgs, values, constKeyword != null));
+  }
+
+  void endLiteralSymbol(token, int dots) {
+    debugEvent('LiteralSymbol');
+    if (ignore) return;
+    push(new SymbolLiteral(popList(dots).join('.')));
+  }
+
+  void handleQualified(period) {
+    debugEvent('Qualified');
+    if (ignore) return;
+    Ref name = pop();
+    Ref prefix = pop();
+    assert(name.prefix == null);
+    assert(prefix.prefix == null);
+    push(new Ref(name.name, prefix));
+  }
+
+  int _withinFunction = 0;
+  void beginFunctionDeclaration(token) {
+    debugEvent("BeginFunctionDeclaration");
+    _withinFunction++;
+  }
+
+  // TODO(sigmund): remove
+  static const _invariantCheckToken = "invariant check: starting a function";
+  // type-variables are the declared parameters on declarations.
+  void handleNoTypeVariables(Token token) {
+    debugEvent("NoTypeVariables");
+    if (ignore) return;
+    push(_invariantCheckToken);
+  }
+
+  void endTypeVariable(Token token, Token extendsOrSuper) {
+    debugEvent("endTypeVariable");
+    assert(ignore);
+  }
+
+  void endTypeVariables(int count, Token beginToken, Token endToken) {
+    debugEvent("TypeVariables");
+    assert(ignore);
+  }
+
+  void beginUnnamedFunction(token) {
+    debugEvent("BeginUnnamedFunction");
+    var check = pop();
+    assert(check == _invariantCheckToken);
+    _withinFunction++;
+  }
+
+  void _endFunction();
+  void endFunctionDeclaration(token) {
+    debugEvent("FunctionDeclaration");
+    _withinFunction--;
+    if (ignore) return;
+    _endFunction();
+  }
+  void endUnnamedFunction(token) {
+    debugEvent("UnnamedFunction");
+    _withinFunction--;
+    if (ignore) return;
+    _endFunction();
+  }
+
+  int _withinCascades = 0;
+  void beginCascade(Token token) {
+    _withinCascades++;
+  }
+
+  void endCascade() {
+    _withinCascades--;
+    throw new UnimplementedError(); // TODO(paulberry): fix the code below.
+    // _endCascade();
+  }
+
+  void endSend(Token beginToken, Token endToken) {
+    debugEvent("EndSend");
+    if (ignore) return;
+    // ignore: strong_mode_down_cast_composite
+    List<Expression> args = pop();
+    if (args != null) {
+      /* var typeArgs = */ pop();
+      var receiver = pop();
+      // TODO(sigmund): consider making identical a binary operator.
+      if (receiver is Ref && receiver.name == 'identical') {
+        assert(receiver.prefix == null);
+        assert(args.length == 2);
+        push(new Identical(args[0], args[1]));
+        return;
+      }
+      _unhandledSend();
+    }
+  }
+
+  void _unhandledSend();
+
+  void endConstructorReference(
+      Token start, Token periodBeforeName, Token endToken) {
+    debugEvent("ConstructorReference $start $periodBeforeName");
+    Ref ctorName = popIfNotNull(periodBeforeName);
+    assert(ctorName?.prefix == null);
+    // ignore: strong_mode_down_cast_composite
+    List<TypeRef> typeArgs = pop();
+    Ref type = pop();
+    push(new ConstructorName(
+          new TypeRef(type, typeArgs), ctorName?.name));
+  }
+
+  void handleModifier(Token token) {
+    debugEvent("Modifier");
+    assert(ignore);
+  }
+
+  void handleModifiers(int count) {
+    debugEvent("Modifiers");
+    assert(ignore);
+  }
+
+  /// Overriden: the base class throws when something is not handled, we avoid
+  /// implementing a few handlers when we know we can ignore them.
+  @override
+  void logEvent(e) {
+    if (ignore) return;
+    super.logEvent(e);
+  }
+
+  // debug helpers
+
+  void debugEvent(String name) {
+    if (const bool.fromEnvironment('CDEBUG', defaultValue: false)) {
+      var s = stack.join(' :: ');
+      if (s == '') s = '<empty>';
+      var bits = '$_withinFunction,$_withinCascades';
+      var prefix = ignore ? "ignore $name on:" : "do $name on:";
+      prefix = '$prefix${" " * (30 - prefix.length)}';
+      print('$prefix $bits $s');
+    }
+  }
+
+  void debugStart(Token token) {
+    debugEvent('\n---- START: $runtimeType ---');
+    if (const bool.fromEnvironment('CDEBUG', defaultValue: false)) {
+      _printExpression(token);
+    }
+  }
+
+  void _printExpression(Token token) {
+    var current = token;
+    var end = new ClassMemberParser(this).skipExpression(current);
+    var str = new StringBuffer();
+    while (current != end) {
+      if (!["(", ",", ")"].contains(current.value)) str.write(' ');
+      str.write(current.value);
+      current = current.next;
+    }
+    print('exp: $str');
+  }
+}
+
+/// Builder for constant expressions.
+///
+/// Any invalid subexpression is denoted with [Invalid].
+class ConstExpressionBuilder extends ExpressionListener {
+  bool get forConst => true;
+  final Uri uri;
+  Parser parser;
+  ConstExpressionBuilder(this.uri) {
+    parser = new Parser(this,
+        asyncAwaitKeywordsEnabled: true);
+  }
+
+  void handleNoConstructorReferenceContinuationAfterTypeArguments(Token token) {
+    debugEvent("NoConstructorReferenceContinuationAfterTypeArguments");
+  }
+
+  void handleAsOperator(Token op, Token next) {
+    debugEvent("As");
+    if (ignore) return;
+    push(new As(pop(), pop()));
+  }
+
+  void handleIndexedExpression(Token openSquareBracket, Token token) {
+    debugEvent("Index");
+    if (ignore) return;
+    pop(); // receiver
+    pop(); // index
+    push(new Invalid(hint: "index"));
+  }
+
+  void handleAssignmentExpression(Token operator) {
+    pop(); // lhs
+    pop(); // rhs
+    push(new Invalid(hint: "assign"));
+  }
+
+  void handleUnaryPrefixAssignmentExpression(Token operator) {
+    pop();
+    push(new Invalid(hint: "prefixOp"));
+  }
+
+  void handleUnaryPostfixAssignmentExpression(Token operator) {
+    pop();
+    push(new Invalid(hint: "postfixOp"));
+  }
+
+  void handleNamedArgument(colon) {
+    debugEvent("NamedArg");
+    if (ignore) return;
+    var value = pop();
+    Ref name = pop();
+    push(new NamedArg(name.name, value));
+  }
+
+  void endArguments(int count, Token begin, Token end) {
+    debugEvent("Arguments");
+    if (ignore) return;
+    push(popList(count) ?? const []);
+  }
+
+  void handleNewExpression(Token token) {
+    debugEvent("NewExpression");
+    if (ignore) return;
+    pop(); // args
+    pop(); // ctor
+    push(new Invalid(hint: "new"));
+  }
+
+  void _endFunction() {
+    assert(_withinFunction >= 0);
+    push(new Invalid(hint: 'function'));
+  }
+
+  // TODO(paulberry): is this needed?

[Siggi Cherem (dart-lang), 2017/03/09 21:02:14]

really depends on how we want to handle recovery of invalid constant
expressions. If we report the error elsewhere and we don't expect to run the
summary builder on invalid code, then we don't need it.

[Paul Berry, 2017/03/09 23:26:23]

We *do* expect to run the summary builder on invalid code.  The only reason this
is commented out for now is because there are currently no callers, so analyzer
was giving me an "unused method" hint.  I'll remove the TODO comment when I fix
this.

+  //void _endCascade() {
+  //  push(new Invalid(hint: 'cascades'));
+  //}
+
+  void _unhandledSend() {
+    push(new Invalid(hint: "call"));
+  }
+}
+
+/// Builder for initializer expressions. These expressions exclude any nested
+/// expression that is not needed to infer strong mode types.
+class InitializerBuilder extends ExpressionListener {
+  final Uri uri;
+  Parser parser;
+
+  InitializerBuilder(this.uri) {
+    parser = new Parser(this,
+        asyncAwaitKeywordsEnabled: true);
+  }
+
+  void handleNoConstructorReferenceContinuationAfterTypeArguments(Token token) {
+    debugEvent("NoConstructorReferenceContinuationAfterTypeArguments");
+  }
+
+  bool get ignore => super.ignore || _inArguments > 0;
+
+  void handleAsOperator(Token op, Token next) {
+    debugEvent("As");
+    if (ignore) return;
+    TypeRef type = pop();
+    pop();
+    push(new Opaque(type: type));
+  }
+
+  // Not necessary, but we don't use the value, so we can abstract it:
+  void handleIsOperator(Token operator, Token not, Token endToken) {
+    debugEvent("Is");
+    if (ignore) return;
+    throw new UnimplementedError(); // TODO(paulberry): fix the code below.

[Siggi Cherem (dart-lang), 2017/03/09 21:02:13]

is the fix related to references in general?

[Paul Berry, 2017/03/09 23:26:23]

I don't know what the proper fix is.  The reason I commented it out is because
the line below produces an analyzer error: TypeRef requires two arguments, not
one.

I plan to fix this code as part of getting the rest of the summary tests to
pass.

+    // push(new Opaque(type: new TypeRef(new Ref('bool'))));
+  }
+
+  void handleIndexedExpression(Token openSquareBracket, Token token) {
+    debugEvent("Index");
+    if (ignore) return;
+    pop();
+    pop();
+    push(new Opaque());
+  }
+
+  void handleAssignmentExpression(Token operator) {
+    debugEvent("Assign");
+    if (ignore) return;
+    var left = pop();
+    var right = pop();
+    var kind = operator.kind;
+    if (kind == EQ_TOKEN) {
+      push(new OpaqueOp(right));
+    } else {
+      push(new OpaqueOp(new Binary(left, right, opForAssignOp(kind))));
+    }
+  }
+
+  void handleUnaryPrefixAssignmentExpression(Token operator) {
+    debugEvent("Prefix");
+    if (ignore) return;
+    var kind = operator.kind == PLUS_PLUS_TOKEN ? PLUS_TOKEN : MINUS_TOKEN;
+    push(new OpaqueOp(new Binary(pop(), new IntLiteral(1), kind)));
+  }
+
+  void handleUnaryPostfixAssignmentExpression(Token operator) {
+    debugEvent("PostFix");
+    if (ignore) return;
+    // the post-fix effect is not visible to the enclosing expression
+    push(new OpaqueOp(pop()));
+  }
+
+  int _inArguments = 0;
+  void beginArguments(Token token) {
+    // TODO(sigmund): determine if we can ignore arguments.
+    //_inArguments++;
+  }
+
+  void handleNamedArgument(colon) {
+    debugEvent("NamedArg");
+    if (ignore) return;
+    pop();
+    pop();
+    push(NullValue.Arguments);
+  }
+
+  void endArguments(int count, Token begin, Token end) {
+    debugEvent("Arguments");
+    //_inArguments--;
+    if (ignore) return;
+    push(popList(count) ?? const []);
+    //push([new Opaque(hint: "arguments")]);
+  }
+
+  void handleNewExpression(Token token) {
+    debugEvent("NewExpression");
+    if (ignore) return;
+    pop(); // args
+    /* var ctor = */ pop(); // ctor
+    throw new UnimplementedError(); // TODO(paulberry): fix the code below.
+    // push(new Opaque(type: ctor.type, hint: "new"));
+  }
+
+  void _endFunction() {
+    push(new Opaque(hint: "function"));
+  }
+
+  // TODO(paulberry): is this needed?
+  //void _endCascade() {
+  //  push(new OpaqueOp(pop(), hint: 'cascades'));
+  //}
+
+  void _unhandledSend() {
+    push(new Opaque(hint: "call"));
+  }
+}
+
+// bit-masks to encode modifiers as bits on an int.
+
+/// Maps modifier names to their bit-mask.
+const _modifierFlag = const {
+  'const': _const_flag,
+  'abstract': _abstract_flag,
+  'static': _static_flag,
+  'external': _external_flag,
+  'final': _final_flag,
+  'var': _var_flag,
+};
+
+const _var_flag = 0;
+const _final_flag = 1;
+const _const_flag = 1 << 1;
+const _abstract_flag = 1 << 2;
+const _static_flag = 1 << 3;
+const _external_flag = 1 << 4;
+
+// bit-masks to encode async modifiers as bits on an int.
+
+const _async_flag = 1;
+const _sync_flag = 1 << 1;
+const _star_flag = 1 << 2;
+
+/// Retrieve the operator from an assignment operator (e.g. + from +=).
+/// Operators are encoded using the scanner token kind id.
+int opForAssignOp(int kind) {
+  switch (kind) {
+    case AMPERSAND_EQ_TOKEN: return AMPERSAND_TOKEN;
+    // TODO(paulberry): add support for &&=
+    // case AMPERSAND_AMPERSAND_EQ_TOKEN: return AMPERSAND_AMPERSAND_TOKEN;
+    case BAR_EQ_TOKEN: return BAR_TOKEN;
+    // TODO(paulberry): add support for ||=
+    // case BAR_BAR_EQ_TOKEN: return BAR_BAR_TOKEN;
+    case CARET_EQ_TOKEN: return CARET_TOKEN;
+    case GT_GT_EQ_TOKEN: return GT_GT_TOKEN;
+    case LT_LT_EQ_TOKEN: return LT_LT_TOKEN;
+    case MINUS_EQ_TOKEN: return MINUS_TOKEN;
+    case PERCENT_EQ_TOKEN: return PERCENT_TOKEN;
+    case PLUS_EQ_TOKEN: return PLUS_TOKEN;
+    case QUESTION_QUESTION_EQ_TOKEN: return QUESTION_QUESTION_TOKEN;
+    case SLASH_EQ_TOKEN: return SLASH_TOKEN;
+    case STAR_EQ_TOKEN: return STAR_TOKEN;
+    case TILDE_SLASH_EQ_TOKEN: return TILDE_SLASH_TOKEN;
+    case PLUS_EQ_TOKEN: return PLUS_TOKEN;
+    default:
+      throw "Unhandled kind $kind";
+  }
+}