Remove default value checking in GN, adds getenv function, reorders parameters to rebase_path.

Remove default value checking in GN, adds getenv function, reorders parameters to rebase_path.

This allows us to have the default value vary according to other parameters. This is what we need in many cases, so having this restriction just made things more complicated.

The getenv function will allow us to replace some Python scripts with a fast native function call.

The use of rebase path is pretty annoying. 99% of all callers want the "from" directory to be the current one. I reordered the parameters to move the from directory later so we can have a default value for it.

This will require a patch to change all current callers of rebase_path when new deps are pulled.

BUG=342937
R=viettrungluu@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=251821

[viettrungluu, 2014-02-12 23:09:33]

LGTM with nits/comments.

Though I don't really know what I'm looking at.

https://codereview.chromium.org/161783002/diff/1/tools/gn/command_args.cc
File tools/gn/command_args.cc (right):

https://codereview.chromium.org/161783002/diff/1/tools/gn/command_args.cc#new...
tools/gn/command_args.cc:48: std::string ret;
Can't this just be something like:

return "   " + line.substr(line.find('#') + 1).as_string();

https://codereview.chromium.org/161783002/diff/1/tools/gn/functions.cc
File tools/gn/functions.cc (right):

https://codereview.chromium.org/161783002/diff/1/tools/gn/functions.cc#newcod...
tools/gn/functions.cc:391: const char* env_result =
getenv(args[0].string_value().c_str());
Does this work properly on Windows?

(You could use base/environment.h. This handles values that are proper Unicode
"properly" (?).)

<shrug>

[brettw, 2014-02-18 20:24:51]

Committed patchset #7 manually as r251821 (presubmit successful).