Use simplify operator< implementations in tools/

Use simplify operator< implementations in tools/

Simplify the code for operator< when comparing multiple members using
a common std::tie idiom. And resolve a TODO when comparing strings.

BUG=555171
R=brettw@chromium.org

Committed: https://crrev.com/850020357f5d66ac342fd387e36dd1fb5c298803
Cr-Commit-Position: refs/heads/master@{#362254}

[jsbell, 2015-11-19 22:29:56]

brettw@ - please take a look?

The chained string compares could also be written:

return (a.compare(rhs.a) || b.compare(rhs.b) || ...) == -1;

... but that may be a bit too subtle.

[brettw, 2015-11-20 21:44:31]

https://codereview.chromium.org/1461623006/diff/1/tools/gn/label.h
File tools/gn/label.h (right):

https://codereview.chromium.org/1461623006/diff/1/tools/gn/label.h#newcode74
tools/gn/label.h:74: if (int c = dir_.compare(other.dir_))
You didn't use tie here to avoid the double-checking?

[jsbell, 2015-11-20 22:04:27]

https://codereview.chromium.org/1461623006/diff/1/tools/gn/label.h
File tools/gn/label.h (right):

https://codereview.chromium.org/1461623006/diff/1/tools/gn/label.h#newcode74
tools/gn/label.h:74: if (int c = dir_.compare(other.dir_))
On 2015/11/20 21:44:31, brettw wrote:
> You didn't use tie here to avoid the double-checking?

Correct. I assumed (based on the TODO) that there was some concern about
performance.

(Happy to redo it with tie, though!)

[brettw, 2015-11-20 22:05:30]

ok, lgtm (this is used in a bunch of maps so can be called a lot).

[jsbell, 2015-11-20 22:06:29]

Although apparently I just assumed these were strings. :P 

I apparently forgot to even build this one locally - sorry, retract the request
for review for now.

[brettw, 2015-11-20 22:17:57]

https://codereview.chromium.org/1461623006/diff/1/tools/gn/label.h
File tools/gn/label.h (right):

https://codereview.chromium.org/1461623006/diff/1/tools/gn/label.h#newcode78
tools/gn/label.h:78: if (int c = toolchain_dir_.compare(other.toolchain_dir_))
You can use value() on the dir names to get the string out (no copies).

[jsbell, 2015-11-20 23:39:47]

The CQ bit was checked by jsbell@chromium.org

[jsbell, 2015-11-20 23:39:48]

The patchset sent to the CQ was uploaded after l-g-t-m from brettw@chromium.org
Link to the patchset: https://codereview.chromium.org/1461623006/#ps20001
(title: "Fix SourceDir compare")

[commit-bot: I haz the power, 2015-11-20 23:41:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1461623006/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1461623006/20001

[commit-bot: I haz the power, 2015-11-21 00:00:50]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-11-21 00:00:51]

Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[jsbell, 2015-11-30 21:02:43]

The CQ bit was checked by jsbell@chromium.org

[jsbell, 2015-11-30 21:02:43]

The patchset sent to the CQ was uploaded after l-g-t-m from brettw@chromium.org
Link to the patchset: https://codereview.chromium.org/1461623006/#ps40001
(title: "Fix string compare checks")

[commit-bot: I haz the power, 2015-11-30 21:08:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1461623006/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1461623006/40001

[commit-bot: I haz the power, 2015-11-30 22:57:53]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-11-30 22:58:37]

Description was changed from

==========
Use simplify operator< implementations in tools/

Simplify the code for operator< when comparing multiple members using
a common std::tie idiom. And resolve a TODO when comparing strings.

BUG=555171
R=brettw@chromium.org
==========

to

==========
Use simplify operator< implementations in tools/

Simplify the code for operator< when comparing multiple members using
a common std::tie idiom. And resolve a TODO when comparing strings.

BUG=555171
R=brettw@chromium.org

Committed: https://crrev.com/850020357f5d66ac342fd387e36dd1fb5c298803
Cr-Commit-Position: refs/heads/master@{#362254}
==========

[commit-bot: I haz the power, 2015-11-30 22:58:37]

Patchset 3 (id:??) landed as
https://crrev.com/850020357f5d66ac342fd387e36dd1fb5c298803
Cr-Commit-Position: refs/heads/master@{#362254}