convert Value::*Value() function to return Maybe results

convert Value::*Value() function to return Maybe results

BUG=v8:3929
LOG=Y

Committed: https://crrev.com/8d839ead046f3b377135509a2264a9e5fecc98ba
Cr-Commit-Position: refs/heads/master@{#26914}

[Sven Panne, 2015-02-27 12:18:00]

svenpanne@chromium.org changed reviewers:
+ svenpanne@chromium.org

[Sven Panne, 2015-02-27 12:18:03]

https://codereview.chromium.org/959223002/diff/1/include/v8.h
File include/v8.h (right):

https://codereview.chromium.org/959223002/diff/1/include/v8.h#newcode984
include/v8.h:984: explicit Maybe(T t) : has_value(true), value(t) {}
While we're here: Make this a "const T& t", the current signature is
embarrassing.

https://codereview.chromium.org/959223002/diff/1/include/v8.h#newcode988
include/v8.h:988: bool HasValue() { return value; }
This should return has_value, I guess...

https://codereview.chromium.org/959223002/diff/1/include/v8.h#newcode991
include/v8.h:991: if (has_value) {
Test is wrong, safer and more obvious way:

  *out = has_value ? value : T();
  return has_value;

https://codereview.chromium.org/959223002/diff/1/src/api.cc
File src/api.cc (right):

https://codereview.chromium.org/959223002/diff/1/src/api.cc#newcode2646
src/api.cc:2646: #define RETURN_MAYBE_DEFAULT(maybe_value, default_value, T)  \
I think this should actually be a member function of Maybe, see
https://hackage.haskell.org/package/base-4.7.0.2/docs/Data-Maybe.html#v:maybe.
But we can do this separately later.

[dcarney, 2015-02-27 12:35:42]

updated, ptal

[Sven Panne, 2015-02-27 12:37:37]

lgtm

[dcarney, 2015-02-27 12:43:12]

The CQ bit was checked by dcarney@chromium.org

[commit-bot: I haz the power, 2015-02-27 12:43:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/959223002/20001

[commit-bot: I haz the power, 2015-02-27 13:04:40]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-02-27 13:04:58]

Patchset 2 (id:??) landed as
https://crrev.com/8d839ead046f3b377135509a2264a9e5fecc98ba
Cr-Commit-Position: refs/heads/master@{#26914}