Add spell-checking to `gn help`.

Add spell-checking to `gn help`.

I tried porting a gyp copies step to gn, and one of the things I tried while
doing so whas `gn help copies`.  If help had spell-checking, it would've
suggested `gn help copy`.  Since that seems like a nice change, add this.

Also stop printing full help output when a topic is not found, because then
the "not found" error scrolls by so fast that I never see it.

Demo:
$ out/gn/gn help copyasdfasdf
ERROR No help on "copyasdfasdf".
Run `gn help` for a list of available topics.
$ out/gn/gn help copies
ERROR No help on "copies".
Did you mean `gn help copy`?

(There's another implementation of EditDistance() in
components/ssl/error_classification.cc -- but that works based on strings
not StringPieces and it doesn't have a "max_distance" parameter.
Since there's only one other instance of this function, just having a second version
of it seems preferrable over finding some place to put this function so it can be used
from both places. I'm however improving the other copy a bit in
https://codereview.chromium.org/1690593002/)

BUG=none

Committed: https://crrev.com/11afb324fa322a3d651124f3ca244c9595f84768
Cr-Commit-Position: refs/heads/master@{#375673}

[Nico, 2016-02-10 16:00:38]

Description was changed from

==========
Add spell-checking to `gn help`.

I tried porting a gyp copies step to gn, and one of the things I tried while
doing so whas `gn help copies`.  If help had spell-checking, it would've
suggested `gn help copy`.  Since that seems like a nice change, add this.

Also stop printing full help output when a topic is not found, because then
the "not found" error scrolls by so fast that I never see it.

Demo:
$ out/gn/gn help copyasdfasdf
ERROR No help on "copyasdfasdf".
Run `gn help` for a list of available topics.
$ out/gn/gn help copies
ERROR No help on "copies".
Did you mean `gn help copy`?

(There's another implementation of EditDistance() in
components/ssl/error_classification.cc -- but that works based on strings
not StringPieces, and since there's only one other instance of this function,
just having a second version of it seems preferrable over finding some place
to put this function so it can be used from both places. I'm however improving
the other copy a bit in https://codereview.chromium.org/1690593002/)

BUG=none
==========

to

==========
Add spell-checking to `gn help`.

I tried porting a gyp copies step to gn, and one of the things I tried while
doing so whas `gn help copies`.  If help had spell-checking, it would've
suggested `gn help copy`.  Since that seems like a nice change, add this.

Also stop printing full help output when a topic is not found, because then
the "not found" error scrolls by so fast that I never see it.

Demo:
$ out/gn/gn help copyasdfasdf
ERROR No help on "copyasdfasdf".
Run `gn help` for a list of available topics.
$ out/gn/gn help copies
ERROR No help on "copies".
Did you mean `gn help copy`?

(There's another implementation of EditDistance() in
components/ssl/error_classification.cc -- but that works based on strings
not StringPieces and it doesn't have a "max_distance" parameter.
Since there's only one other instance of this function, just having a second
version
of it seems preferrable over finding some place to put this function so it can
be used
from both places. I'm however improving the other copy a bit in
https://codereview.chromium.org/1690593002/)

BUG=none
==========

[Nico, 2016-02-10 16:01:37]

thakis@chromium.org changed reviewers:
+ brettw@chromium.org

[Nico, 2016-02-10 16:01:37]

wdyt? cool? lame? If you like this, maybe a few others of gn's arguments could
be spell-checked too

[Nico, 2016-02-10 23:39:32]

thakis@chromium.org changed reviewers:
+ dpranke@chromium.org

[Nico, 2016-02-10 23:39:32]

+dpranke here too (but maybe he'll want to wait for brettw for this, not sure)

[Dirk Pranke, 2016-02-10 23:47:25]

I think this is a good idea, and the implementation lgtm , but we should
probably wait for Brett to take a look as well.

Side note: I'm pretty sure I got "implement the Levenshtein distance" as a
question when interviewing at Google :).

[brettw, 2016-02-16 20:48:28]

LGTM

https://codereview.chromium.org/1681363003/diff/60001/tools/gn/command_help.cc
File tools/gn/command_help.cc (right):

https://codereview.chromium.org/1681363003/diff/60001/tools/gn/command_help.c...
tools/gn/command_help.cc:146: size_t EditDistance(const base::StringPiece& s1,
This is exciting, I've been wanting to add spellchecking to various commands.

As such, can you put this in tools/gn/string_utils.h and add a unit test for it?

[Nico, 2016-02-16 21:19:18]

On 2016/02/16 20:48:28, brettw wrote:
> LGTM

Thanks!

> https://codereview.chromium.org/1681363003/diff/60001/tools/gn/command_help.cc
> File tools/gn/command_help.cc (right):
> 
>
https://codereview.chromium.org/1681363003/diff/60001/tools/gn/command_help.c...
> tools/gn/command_help.cc:146: size_t EditDistance(const base::StringPiece& s1,
> This is exciting, I've been wanting to add spellchecking to various commands.
> 
> As such, can you put this in tools/gn/string_utils.h and add a unit test for
it?

Done.

[Nico, 2016-02-16 21:19:24]

The CQ bit was checked by thakis@chromium.org

[Nico, 2016-02-16 21:19:24]

The patchset sent to the CQ was uploaded after l-g-t-m from
dpranke@chromium.org, brettw@chromium.org
Link to the patchset: https://codereview.chromium.org/1681363003/#ps100001
(title: "move to string_utils, add tests")

[commit-bot: I haz the power, 2016-02-16 21:21:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1681363003/100001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1681363003/100001

[commit-bot: I haz the power, 2016-02-16 21:58:07]

Description was changed from

==========
Add spell-checking to `gn help`.

I tried porting a gyp copies step to gn, and one of the things I tried while
doing so whas `gn help copies`.  If help had spell-checking, it would've
suggested `gn help copy`.  Since that seems like a nice change, add this.

Also stop printing full help output when a topic is not found, because then
the "not found" error scrolls by so fast that I never see it.

Demo:
$ out/gn/gn help copyasdfasdf
ERROR No help on "copyasdfasdf".
Run `gn help` for a list of available topics.
$ out/gn/gn help copies
ERROR No help on "copies".
Did you mean `gn help copy`?

(There's another implementation of EditDistance() in
components/ssl/error_classification.cc -- but that works based on strings
not StringPieces and it doesn't have a "max_distance" parameter.
Since there's only one other instance of this function, just having a second
version
of it seems preferrable over finding some place to put this function so it can
be used
from both places. I'm however improving the other copy a bit in
https://codereview.chromium.org/1690593002/)

BUG=none
==========

to

==========
Add spell-checking to `gn help`.

I tried porting a gyp copies step to gn, and one of the things I tried while
doing so whas `gn help copies`.  If help had spell-checking, it would've
suggested `gn help copy`.  Since that seems like a nice change, add this.

Also stop printing full help output when a topic is not found, because then
the "not found" error scrolls by so fast that I never see it.

Demo:
$ out/gn/gn help copyasdfasdf
ERROR No help on "copyasdfasdf".
Run `gn help` for a list of available topics.
$ out/gn/gn help copies
ERROR No help on "copies".
Did you mean `gn help copy`?

(There's another implementation of EditDistance() in
components/ssl/error_classification.cc -- but that works based on strings
not StringPieces and it doesn't have a "max_distance" parameter.
Since there's only one other instance of this function, just having a second
version
of it seems preferrable over finding some place to put this function so it can
be used
from both places. I'm however improving the other copy a bit in
https://codereview.chromium.org/1690593002/)

BUG=none
==========

[commit-bot: I haz the power, 2016-02-16 21:58:08]

Committed patchset #6 (id:100001)

[commit-bot: I haz the power, 2016-02-16 22:55:10]

Description was changed from

==========
Add spell-checking to `gn help`.

I tried porting a gyp copies step to gn, and one of the things I tried while
doing so whas `gn help copies`.  If help had spell-checking, it would've
suggested `gn help copy`.  Since that seems like a nice change, add this.

Also stop printing full help output when a topic is not found, because then
the "not found" error scrolls by so fast that I never see it.

Demo:
$ out/gn/gn help copyasdfasdf
ERROR No help on "copyasdfasdf".
Run `gn help` for a list of available topics.
$ out/gn/gn help copies
ERROR No help on "copies".
Did you mean `gn help copy`?

(There's another implementation of EditDistance() in
components/ssl/error_classification.cc -- but that works based on strings
not StringPieces and it doesn't have a "max_distance" parameter.
Since there's only one other instance of this function, just having a second
version
of it seems preferrable over finding some place to put this function so it can
be used
from both places. I'm however improving the other copy a bit in
https://codereview.chromium.org/1690593002/)

BUG=none
==========

to

==========
Add spell-checking to `gn help`.

I tried porting a gyp copies step to gn, and one of the things I tried while
doing so whas `gn help copies`.  If help had spell-checking, it would've
suggested `gn help copy`.  Since that seems like a nice change, add this.

Also stop printing full help output when a topic is not found, because then
the "not found" error scrolls by so fast that I never see it.

Demo:
$ out/gn/gn help copyasdfasdf
ERROR No help on "copyasdfasdf".
Run `gn help` for a list of available topics.
$ out/gn/gn help copies
ERROR No help on "copies".
Did you mean `gn help copy`?

(There's another implementation of EditDistance() in
components/ssl/error_classification.cc -- but that works based on strings
not StringPieces and it doesn't have a "max_distance" parameter.
Since there's only one other instance of this function, just having a second
version
of it seems preferrable over finding some place to put this function so it can
be used
from both places. I'm however improving the other copy a bit in
https://codereview.chromium.org/1690593002/)

BUG=none

Committed: https://crrev.com/11afb324fa322a3d651124f3ca244c9595f84768
Cr-Commit-Position: refs/heads/master@{#375673}
==========

[commit-bot: I haz the power, 2016-02-16 22:55:11]

Patchset 6 (id:??) landed as
https://crrev.com/11afb324fa322a3d651124f3ca244c9595f84768
Cr-Commit-Position: refs/heads/master@{#375673}

[jbroman, 2016-02-17 00:03:08]

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

[jbroman, 2016-02-17 00:03:09]

drive-by ex-post-facto comment

https://codereview.chromium.org/1681363003/diff/100001/tools/gn/command_help.cc
File tools/gn/command_help.cc (right):

https://codereview.chromium.org/1681363003/diff/100001/tools/gn/command_help....
tools/gn/command_help.cc:227: random_topics["buildargs"] = [=]() {
PrintLongHelp(kBuildArgs_Help); };
Sorry to drop in since I actually quite like this, but lambda default capture
(which doesn't even seem necessary here -- is anything captured?) is banned by
styleguide/c++/c++11.html (see chromium-cpp.appspot.com), and std::function
isn't approved yet either (Chromium largely uses base::Callback).

Since all of these seem to be valid as captureless lambdas, perhaps:

std::map<std::string, void(*)()> random_topics;
random_topics["all"] = PrintAllHelp;
random_topics["buildargs"] = []() { PrintLongHelp(kBuildArgs_Help); };
// etc.

[Nico, 2016-02-17 20:43:53]

https://codereview.chromium.org/1681363003/diff/100001/tools/gn/command_help.cc
File tools/gn/command_help.cc (right):

https://codereview.chromium.org/1681363003/diff/100001/tools/gn/command_help....
tools/gn/command_help.cc:227: random_topics["buildargs"] = [=]() {
PrintLongHelp(kBuildArgs_Help); };
On 2016/02/17 00:03:09, jbroman wrote:
> Sorry to drop in since I actually quite like this, but lambda default capture
> (which doesn't even seem necessary here -- is anything captured?) is banned by
> styleguide/c++/c++11.html (see http://chromium-cpp.appspot.com), and
std::function
> isn't approved yet either (Chromium largely uses base::Callback).
> 
> Since all of these seem to be valid as captureless lambdas, perhaps:
> 
> std::map<std::string, void(*)()> random_topics;
> random_topics["all"] = PrintAllHelp;
> random_topics["buildargs"] = []() { PrintLongHelp(kBuildArgs_Help); };
> // etc.

Thanks, good comments. Addressing them here:
https://codereview.chromium.org/1705123004/