Share code for parsing local functions.

pkg/front_end/lib/src/incremental/unlinked_unit.dart

 // 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.
 
 import 'dart:typed_data';
 
 import 'package:front_end/src/base/api_signature.dart';
 import 'package:front_end/src/fasta/parser.dart'
     show Listener, Parser, optional;
 import 'package:front_end/src/fasta/parser/top_level_parser.dart';
@@ skipping 96 matching lines @@
   bool hasMixin = false;
   final List<_BodyRange> bodyRanges = [];
 
   _BodySkippingParser() : super(new Listener());
 
   @override
   Token parseFunctionBody(Token token, bool isExpression, bool allowAbstract) {
     if (identical('{', token.lexeme)) {
       Token close = skipBlock(token);
       bodyRanges.add(new _BodyRange(token.charOffset, close.charOffset));
-      return close;
+      return isExpression ? close.next : close;

[scheglov, 2017/08/08 01:42:27]

I don't understand this change.
How could it be an expression if it starts with '{'?

[ahe, 2017/08/08 08:13:30]

[isExpression] is true if the function is in expression context, for example:

print(() { return "I'm a function in expression context."; }());

foo() {
  print("I'm a function in statement context, or a declaration.");
}

There's a subtle difference in expression context when using the arrow notation:

print(() => "I don't have a trailing semicolon.");

bar() => "But I do.";

The way I deal with that difference is by having this invariant: when parsing a
function expression, this method returns the next token which isn't part of the
expression. Otherwise, this is a function declaration, and we always return the
end token (which is a "}" for a function with a block body, and semicolon for
arrow notation).

[scheglov, 2017/08/08 15:54:57]

Now I understand.
Thank you.

[ahe, 2017/08/08 16:03:33]

Great. Would it have been less confusing initially if I had called this boolean
"isFunctionExpression"?

[scheglov, 2017/08/08 16:06:03]

Even better would be "ofFunctionExpression", because the body we're parsing
*isn't* function expression, but a part of it.

     }
     return super.parseFunctionBody(token, isExpression, allowAbstract);
   }
 
   Token parseMixinApplicationRest(Token token) {
     hasMixin = true;
     return super.parseMixinApplicationRest(token);
   }
 }