Implement ParseExportDeclaration per latest ES6 spec draft

Implement ParseExportDeclaration per latest ES6 spec draft

One missing feature: anonymous function & class declarations
in "export default".

BUG=v8:1569
LOG=n
R=arv@chromium.org

Committed: https://crrev.com/f7dc15febeea78b22de1f57c397a3221a43d9213
Cr-Commit-Position: refs/heads/master@{#26313}

[adamk, 2015-01-28 00:01:53]

adamk@chromium.org changed reviewers:
+ arv@chromium.org, rossberg@chromium.org

[adamk, 2015-01-28 00:01:54]

Here's exports, which seemed like a big enough patch to do at a time. I can also
batch this together with imports when that's done, but I figured the smaller,
the better.

https://codereview.chromium.org/882893002/diff/1/test/cctest/test-parsing.cc
File test/cctest/test-parsing.cc (right):

https://codereview.chromium.org/882893002/diff/1/test/cctest/test-parsing.cc#...
test/cctest/test-parsing.cc:4676: "export var y = 0;",
These lists of strings aren't supported by 'git cl format': it tries to reflow
them to fit as many on a line as possible. Any suggestions for what I should do
to avoid that?

[adamk, 2015-01-28 00:01:55]

Here's exports, which seemed like a big enough patch to do at a time. I can also
batch this together with imports when that's done, but I figured the smaller,
the better.

[arv (Not doing code reviews), 2015-01-28 02:57:19]

LGTM

https://codereview.chromium.org/882893002/diff/1/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/882893002/diff/1/src/parser.cc#newcode1384
src/parser.cc:1384: case Token::FUNCTION:
This is going to be problematic. export default supports exporting function
expressions too.

```js
export default function() {}
```

We need to do some lookahead that is currently not covered by the current code.

Can you add a TODO?

https://codereview.chromium.org/882893002/diff/1/src/parser.cc#newcode1389
src/parser.cc:1389: result = ParseClassDeclaration(NULL, CHECK_OK);
Same here

https://codereview.chromium.org/882893002/diff/1/test/cctest/test-parsing.cc
File test/cctest/test-parsing.cc (right):

https://codereview.chromium.org/882893002/diff/1/test/cctest/test-parsing.cc#...
test/cctest/test-parsing.cc:4747: "var a; export { a",
Add test for `export {,}`?

[adamk, 2015-01-28 18:05:04]

https://codereview.chromium.org/882893002/diff/1/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/882893002/diff/1/src/parser.cc#newcode1384
src/parser.cc:1384: case Token::FUNCTION:
On 2015/01/28 02:57:19, arv wrote:
> This is going to be problematic. export default supports exporting function
> expressions too.
> 
> ```js
> export default function() {}
> ```
> 
> We need to do some lookahead that is currently not covered by the current
code.
> 
> Can you add a TODO?
> 

That's the TODO above about FunctionDeclaration[Default] (that's what the
grammar calls this sort of anonymous function declaration). I've moved the TODO
down to these two places. Also added failing tests with a TODO.

https://codereview.chromium.org/882893002/diff/1/test/cctest/test-parsing.cc
File test/cctest/test-parsing.cc (right):

https://codereview.chromium.org/882893002/diff/1/test/cctest/test-parsing.cc#...
test/cctest/test-parsing.cc:4747: "var a; export { a",
On 2015/01/28 02:57:19, arv wrote:
> Add test for `export {,}`?

Done.

[adamk, 2015-01-28 19:18:54]

Committed patchset #3 (id:40001) manually as
f7dc15febeea78b22de1f57c397a3221a43d9213 (presubmit successful).

[commit-bot: I haz the power, 2015-01-28 19:18:56]

Patchset 3 (id:??) landed as
https://crrev.com/f7dc15febeea78b22de1f57c397a3221a43d9213
Cr-Commit-Position: refs/heads/master@{#26313}

[impinball, 2015-01-29 18:31:03]

On 2015/01/28 02:57:19, arv wrote:
> LGTM
> 
> https://codereview.chromium.org/882893002/diff/1/src/parser.cc
> File src/parser.cc (right):
> 
> https://codereview.chromium.org/882893002/diff/1/src/parser.cc#newcode1384
> src/parser.cc:1384: case Token::FUNCTION:
> This is going to be problematic. export default supports exporting function
> expressions too.
> 
> ```js
> export default function() {}
> ```
> 
> We need to do some lookahead that is currently not covered by the current
code.
> 
> Can you add a TODO?
> 
> https://codereview.chromium.org/882893002/diff/1/src/parser.cc#newcode1389
> src/parser.cc:1389: result = ParseClassDeclaration(NULL, CHECK_OK);
> Same here
> 
> https://codereview.chromium.org/882893002/diff/1/test/cctest/test-parsing.cc
> File test/cctest/test-parsing.cc (right):
> 
>
https://codereview.chromium.org/882893002/diff/1/test/cctest/test-parsing.cc#...
> test/cctest/test-parsing.cc:4747: "var a; export { a",
> Add test for `export {,}`?

@arv, you can also default export a named function. These two are equivalent:

```js
export default function foo() {}

function foo() {}
export default foo;
```

I'm aware that this is already committed, but it's just a note for the future.

[adamk, 2015-01-29 18:34:12]

On 2015/01/29 18:31:03, impinball wrote:
> On 2015/01/28 02:57:19, arv wrote:
> > LGTM
> > 
> > https://codereview.chromium.org/882893002/diff/1/src/parser.cc
> > File src/parser.cc (right):
> > 
> > https://codereview.chromium.org/882893002/diff/1/src/parser.cc#newcode1384
> > src/parser.cc:1384: case Token::FUNCTION:
> > This is going to be problematic. export default supports exporting function
> > expressions too.
> > 
> > ```js
> > export default function() {}
> > ```
> > 
> > We need to do some lookahead that is currently not covered by the current
> code.
> > 
> > Can you add a TODO?
> > 
> > https://codereview.chromium.org/882893002/diff/1/src/parser.cc#newcode1389
> > src/parser.cc:1389: result = ParseClassDeclaration(NULL, CHECK_OK);
> > Same here
> > 
> > https://codereview.chromium.org/882893002/diff/1/test/cctest/test-parsing.cc
> > File test/cctest/test-parsing.cc (right):
> > 
> >
>
https://codereview.chromium.org/882893002/diff/1/test/cctest/test-parsing.cc#...
> > test/cctest/test-parsing.cc:4747: "var a; export { a",
> > Add test for `export {,}`?
> 
> @arv, you can also default export a named function. These two are equivalent:
> 
> ```js
> export default function foo() {}
> 
> function foo() {}
> export default foo;
> ```
> 
> I'm aware that this is already committed, but it's just a note for the future.

I don't think there was any confusion about that. The point arv was raising was
that the committed code does not support the anonymous version, but does support
both

export default function foo() {}

and

function foo() {}
export default foo

(via the ParseAssignmentExpression production).