Add the ability to code generated prepopulated static nested structs

Add the ability to code generated prepopulated static nested structs

BUG=504075
Committed: https://crrev.com/e9d5d17980fdc0285bdfccc25b489f17584542ed
Cr-Commit-Position: refs/heads/master@{#338065}

[danduong, 2015-06-24 21:03:04]

danduong@chromium.org changed reviewers:
+ asvitkine@chromium.org, beaudoin@chromium.org

[danduong, 2015-06-24 23:38:33]

Philippe, I've updated elements of json_to_struct to be able to deal with nested
structures. This is required by a feature to build
fieldtrial_testing_config.json into Chrome.  Let me know if you have any
questions.

[beaudoin, 2015-07-06 16:01:12]

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/elemen...
File tools/json_to_struct/element_generator.py (right):

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/elemen...
tools/json_to_struct/element_generator.py:8: field_name_count = {}
Module-global mutable variables are against the style guide:

https://google-styleguide.googlecode.com/svn/trunk/pyguide.html#Global_variables

It's annoying but much cleaner to define it in _GenerateCC and pass into
GenerateElements. It will also make it easier for you to write a test that
validates appending a count behaves as expected. (Please add that test.)

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/elemen...
tools/json_to_struct/element_generator.py:91: content is not specified, uses
{0}.
Why {0}? Is this always a valid C++ object? Just for testing? Is it expected to
cause a compiling error? If the latter, shouldn't we just fail right away?

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/json_t...
File tools/json_to_struct/json_to_struct.py (right):

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/json_t...
tools/json_to_struct/json_to_struct.py:15: #       "type": "enum",   // Either:
int, string, string16, enum, array.
Update doc to add 'object' here, with an example.

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/struct...
File tools/json_to_struct/struct_generator.py (right):

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/struct...
tools/json_to_struct/struct_generator.py:31: elif type == 'object':
Would 'struct' be better than 'object' given that "object" typically refers to
an instance and here we're talking about the type. Also, object makes me think
of 'class' rather than 'struct'. Anyway, your call.

[danduong, 2015-07-08 23:07:03]

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/elemen...
File tools/json_to_struct/element_generator.py (right):

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/elemen...
tools/json_to_struct/element_generator.py:8: field_name_count = {}
On 2015/07/06 at 16:01:11, beaudoin wrote:
> Module-global mutable variables are against the style guide:
> 
>
https://google-styleguide.googlecode.com/svn/trunk/pyguide.html#Global_variables
> 
> It's annoying but much cleaner to define it in _GenerateCC and pass into
GenerateElements. It will also make it easier for you to write a test that
validates appending a count behaves as expected. (Please add that test.)

Done.

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/elemen...
tools/json_to_struct/element_generator.py:91: content is not specified, uses
{0}.
On 2015/07/06 at 16:01:11, beaudoin wrote:
> Why {0}? Is this always a valid C++ object? Just for testing? Is it expected
to cause a compiling error? If the latter, shouldn't we just fail right away?

{0} should compile. That will initialize the first element of the struct to 0. A
partially initialized struct has deterministic behavior (rest of the fields will
be zero'd out). I've seen other places where this is done in our codebase.

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/json_t...
File tools/json_to_struct/json_to_struct.py (right):

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/json_t...
tools/json_to_struct/json_to_struct.py:15: #       "type": "enum",   // Either:
int, string, string16, enum, array.
On 2015/07/06 at 16:01:12, beaudoin wrote:
> Update doc to add 'object' here, with an example.

Done.

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/struct...
File tools/json_to_struct/struct_generator.py (right):

https://codereview.chromium.org/1209733002/diff/1/tools/json_to_struct/struct...
tools/json_to_struct/struct_generator.py:31: elif type == 'object':
On 2015/07/06 at 16:01:12, beaudoin wrote:
> Would 'struct' be better than 'object' given that "object" typically refers to
an instance and here we're talking about the type. Also, object makes me think
of 'class' rather than 'struct'. Anyway, your call.

Done.

[beaudoin, 2015-07-09 14:39:25]

Nice feature! I like it! :)

LGTM

[Alexei Svitkine (slow), 2015-07-09 15:01:49]

lgtm

[danduong, 2015-07-09 15:34:30]

The CQ bit was checked by danduong@chromium.org

[commit-bot: I haz the power, 2015-07-09 15:35:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1209733002/20002

[commit-bot: I haz the power, 2015-07-09 17:11:15]

Committed patchset #4 (id:20002)

[commit-bot: I haz the power, 2015-07-09 17:12:14]

Patchset 4 (id:??) landed as
https://crrev.com/e9d5d17980fdc0285bdfccc25b489f17584542ed
Cr-Commit-Position: refs/heads/master@{#338065}