Add support for rethrow and start treating throw <expr> as an expression.

Add support for rethrow and start treating throw <expr> as an expression.

R=ngeoffray@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=21930

[ahe, 2013-04-23 09:37:25]

https://codereview.chromium.org/14211008/diff/1/sdk/lib/_internal/compiler/im...
File sdk/lib/_internal/compiler/implementation/scanner/parser.dart (right):

https://codereview.chromium.org/14211008/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/scanner/parser.dart:1204: return
parseRethrowStatement(token);
I think this should report a deprecated feature. IIRC, the listener has a method
for that.

https://codereview.chromium.org/14211008/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/scanner/parser.dart:1358: return
parseThrowExpression(token, true);
I don't think this will handle situations like "1 + throw foo". You need to
incorporate this in parsePrecedenceExpression and determine the "precedence" of
throw as a prefix unary operator.

Also, by not using precedence info, you're probably making parsing of
expressions slower.

[kasperl, 2013-04-23 11:26:12]

https://codereview.chromium.org/14211008/diff/1/sdk/lib/_internal/compiler/im...
File sdk/lib/_internal/compiler/implementation/scanner/parser.dart (right):

https://codereview.chromium.org/14211008/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/scanner/parser.dart:1204: return
parseRethrowStatement(token);
On 2013/04/23 09:37:25, ahe wrote:
> I think this should report a deprecated feature. IIRC, the listener has a
method
> for that. 

Done in the listener.

https://codereview.chromium.org/14211008/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/scanner/parser.dart:1358: return
parseThrowExpression(token, true);
On 2013/04/23 09:37:25, ahe wrote:
> I don't think this will handle situations like "1 + throw foo". You need to
> incorporate this in parsePrecedenceExpression and determine the "precedence"
of
> throw as a prefix unary operator.
> 
> Also, by not using precedence info, you're probably making parsing of
> expressions slower. 

I think that is true, but the grammar in the specification doesn't seem to allow
'1 + throw 1' since throw isn't a multiplicative expression. I agree that the
grammar is a bit messed up, but what I've implemented here seems to match it and
the VM behavior. I'm all for changing that of course.

[kasperl, 2013-04-24 06:00:00]

Do you have any comments, Nicolas? I'll chat with Peter about this when he's
back.

[ngeoffray, 2013-04-24 08:08:02]

LGTM

[kasperl, 2013-04-24 08:24:41]

Committed patchset #3 manually as r21930 (presubmit successful).