Fix parsing [a]sync[*] function body modifiers with Fasta.

pkg/front_end/lib/src/fasta/analyzer/ast_builder.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library fasta.analyzer.ast_builder;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/dart/ast/ast_factory.dart' show AstFactory;
 import 'package:analyzer/dart/ast/standard_ast_factory.dart' as standard;
 import 'package:analyzer/dart/ast/token.dart' as analyzer show Token;
 import 'package:analyzer/dart/element/element.dart' show Element;
 import 'package:front_end/src/fasta/parser/parser.dart'
     show FormalParameterType;
 import 'package:front_end/src/fasta/scanner/token.dart'
     show BeginGroupToken, Token;
-import 'package:kernel/ast.dart' show AsyncMarker;
 
 import '../errors.dart' show internalError;
 import '../kernel/kernel_builder.dart'
     show Builder, KernelLibraryBuilder, ProcedureBuilder;
 import '../parser/identifier_context.dart' show IdentifierContext;
 import '../quote.dart';
-import '../source/outline_builder.dart' show asyncMarkerFromTokens;
 import '../source/scope_listener.dart'
     show JumpTargetKind, NullValue, Scope, ScopeListener;
 import 'analyzer.dart' show toKernel;
 import 'element_store.dart'
     show
         AnalyzerLocalVariableElemment,
         AnalyzerParameterElement,
         ElementStore,
         KernelClassElement;
 import 'token_utils.dart' show toAnalyzerToken;
@@ skipping 186 matching lines @@
     debugEvent("ExpressionStatement");
     push(ast.expressionStatement(pop(), toAnalyzerToken(token)));
   }
 
   void endFunctionBody(int count, Token beginToken, Token endToken) {
     debugEvent("FunctionBody");
     List statements = popList(count);
     if (beginToken != null) {
       exitLocalScope();
     }
-    push(ast.block(
-        toAnalyzerToken(beginToken), statements, toAnalyzerToken(endToken)));
+    Block block = ast.block(
+        toAnalyzerToken(beginToken), statements, toAnalyzerToken(endToken));
+    analyzer.Token star = pop();
+    analyzer.Token asyncKeyword = pop();
+    push(ast.blockFunctionBody(asyncKeyword, star, block));
   }
 
-  void finishFunction(formals, asyncModifier, Statement body) {
+  void finishFunction(formals, asyncModifier, FunctionBody body) {
     debugEvent("finishFunction");
-    var kernel = toKernel(body, elementStore, library.library, scope);
+    Statement bodyStatement;
+    if (body is ExpressionFunctionBody) {
+      bodyStatement = ast.returnStatement(null, body.expression, null);
+    } else {
+      bodyStatement = (body as BlockFunctionBody).block;
+    }
+    var kernel = toKernel(bodyStatement, elementStore, library.library, scope);
     if (member is ProcedureBuilder) {
       ProcedureBuilder builder = member;
       builder.body = kernel;
     } else {
       internalError("Internal error: expected procedure, but got: $member");
     }
   }
 
   void beginCascade(Token token) {
     debugEvent("beginCascade");
@@ skipping 50 matching lines @@
       internalError(
           "Unhandled property access: ${identifierOrInvoke.runtimeType}");
     }
   }
 
   void handleLiteralInt(Token token) {
     debugEvent("LiteralInt");
     push(ast.integerLiteral(toAnalyzerToken(token), int.parse(token.value)));
   }
 
+  void endExpressionFunctionBody(Token arrowToken, Token endToken) {
+    debugEvent("ExpressionFunctionBody");
+    Expression expression = pop();
+    analyzer.Token star = pop();
+    analyzer.Token asyncKeyword = pop();
+    assert(star == null);
+    push(ast.expressionFunctionBody(asyncKeyword, toAnalyzerToken(arrowToken),
+        expression, toAnalyzerToken(endToken)));
+  }
+
   void endReturnStatement(
       bool hasExpression, Token beginToken, Token endToken) {
     debugEvent("ReturnStatement");
     Expression expression = hasExpression ? pop() : null;
     push(ast.returnStatement(
         toAnalyzerToken(beginToken), expression, toAnalyzerToken(endToken)));
   }
 
   void endIfStatement(Token ifToken, Token elseToken) {
     Statement elsePart = popIfNotNull(elseToken);
@@ skipping 111 matching lines @@
       int count, Token beginToken, Token constKeyword, Token endToken) {
     debugEvent("LiteralList");
     List<Expression> expressions = popList(count);
     TypeArgumentList typeArguments = pop();
     push(ast.listLiteral(toAnalyzerToken(constKeyword), typeArguments,
         toAnalyzerToken(beginToken), expressions, toAnalyzerToken(endToken)));
   }
 
   void handleAsyncModifier(Token asyncToken, Token starToken) {
     debugEvent("AsyncModifier");
-    push(asyncMarkerFromTokens(asyncToken, starToken));
+    push(toAnalyzerToken(asyncToken) ?? NullValue.FunctionBodyAsyncToken);
+    push(toAnalyzerToken(starToken) ?? NullValue.FunctionBodyStarToken);
   }
 
   void endAwaitExpression(Token beginToken, Token endToken) {
     debugEvent("AwaitExpression");
     push(ast.awaitExpression(toAnalyzerToken(beginToken), pop()));
   }
 
   void handleLiteralBool(Token token) {
     debugEvent("LiteralBool");
     bool value = identical(token.stringValue, "true");
@@ skipping 310 matching lines @@
   void handleModifier(Token token) {
     debugEvent("Modifier");
     push(token);
   }
 
   void handleModifiers(int count) {
     debugEvent("Modifiers");
     push(popList(count) ?? const <Token>[]);
   }
 
-  FunctionBody _endFunctionBody() {
-    AstNode body = pop();
-    // TODO(paulberry): asyncMarker should have a type that allows constructing
-    // the necessary analyzer AST data structures.
-    AsyncMarker asyncMarker = pop();
-    assert(asyncMarker == AsyncMarker.Sync);
-    analyzer.Token asyncKeyword = null;
-    analyzer.Token star = null;
-    if (body is Block) {
-      return ast.blockFunctionBody(asyncKeyword, star, body);
-    } else if (body is ReturnStatement) {
-      assert(star == null);
-      return ast.expressionFunctionBody(
-          asyncKeyword, body.returnKeyword, body.expression, body.semicolon);
-    } else {
-      return internalError(
-          'Unexpected function body type: ${body.runtimeType}');
-    }
-  }
-
   void endTopLevelMethod(Token beginToken, Token getOrSet, Token endToken) {
     // TODO(paulberry): set up scopes properly to resolve parameters and type
     // variables.
     debugEvent("TopLevelMethod");
-    FunctionBody body = _endFunctionBody();
+    FunctionBody body = pop();
     FormalParameterList parameters = pop();
     TypeParameterList typeParameters = pop();
     SimpleIdentifier name = pop();
     analyzer.Token propertyKeyword = toAnalyzerToken(getOrSet);
     TypeAnnotation returnType = pop();
     Token externalKeyword = _popOptionalSingleModifier();
     List<Annotation> metadata = pop();
     // TODO(paulberry): capture doc comments.  See dartbug.com/28851.
     Comment comment = null;
     push(ast.functionDeclaration(
@@ skipping 301 matching lines @@
     push(ast.partOfDirective(comment, metadata, toAnalyzerToken(partKeyword),
         toAnalyzerToken(ofKeyword), uri, name, toAnalyzerToken(semicolon)));
   }
 
   void endUnnamedFunction(Token token) {
     // TODO(paulberry): set up scopes properly to resolve parameters and type
     // variables.  Note that this is tricky due to the handling of initializers
     // in constructors, so the logic should be shared with BodyBuilder as much
     // as possible.
     debugEvent("UnnamedFunction");
-    var body = _endFunctionBody();
+    FunctionBody body = pop();
     FormalParameterList parameters = pop();
     TypeParameterList typeParameters = pop();
     push(ast.functionExpression(typeParameters, parameters, body));
   }
 
   @override
   void handleNoFieldInitializer(Token token) {
     debugEvent("NoFieldInitializer");
     SimpleIdentifier name = pop();
     push(ast.variableDeclaration(name, null, null));
@@ skipping 41 matching lines @@
   void endTypeVariables(int count, Token beginToken, Token endToken) {
     debugEvent("TypeVariables");
     List<TypeParameter> typeParameters = popList(count);
     push(ast.typeParameterList(toAnalyzerToken(beginToken), typeParameters,
         toAnalyzerToken(endToken)));
   }
 
   @override
   void endMethod(Token getOrSet, Token beginToken, Token endToken) {
     debugEvent("Method");
-    FunctionBody body = _endFunctionBody();
+    FunctionBody body = pop();
     ConstructorName redirectedConstructor = null; // TODO(paulberry)
     List<ConstructorInitializer> initializers = null; // TODO(paulberry)
     Token separator = null; // TODO(paulberry)
     FormalParameterList parameters = pop();
     TypeParameterList typeParameters = pop(); // TODO(paulberry)
     var name = pop();
     TypeAnnotation returnType = pop(); // TODO(paulberry)
     Token modifierKeyword = null; // TODO(paulberry)
     Token externalKeyword = null;
     Token constKeyword = null;
@@ skipping 244 matching lines @@
 }
 
 /// Data structure placed on the stack to represent the keyword "operator"
 /// followed by a token.
 class _OperatorName {
   final Token operatorKeyword;
   final SimpleIdentifier name;
 
   _OperatorName(this.operatorKeyword, this.name);
 }