Allow piping into semver to read versions

[richardgarnier]

This is a patch for #149.

Before entering the main, we check if the process is piped. If so then we fill the versions array and then we launch the main. In order to fill the array, we split on spaces.

NB : versions can be accepted both from the pipe and as arguments.
For example echo 1.0.0 | semver -r '>=1' 1.1.1 is accepted.

NB2 : testing relies on comparing the output of the version without piping, and the version with piping.

[coveralls]

Coverage remained the same at 94.624% when pulling 0841679 on akatsukle:master into 8bd070b on npm:master.

[richardgarnier]

I guess the break here was missing. This is not the main purpose of the patch though.

[isaacs]

A break isn't strictly necessary here, since the return is just as effective at ending the block. But if a linter or something is complaining about it, whatever.

[coveralls]

Coverage remained the same at 94.624% when pulling e63742a on akatsukle:master into 8bd070b on npm:master.

[coveralls]

Coverage remained the same at 94.624% when pulling d4ca6fb on akatsukle:master into 8bd070b on npm:master.

[coveralls]

Coverage remained the same at 94.624% when pulling d149eb4 on akatsukle:master into 8bd070b on npm:master.

[richardgarnier]

Well that test was embarrassing... sorry

[isaacs]

This is ok, and seems to work, but it seems like it'd be better to open stdin, and parse/filter each version as lines are read. That way it could be done interactively. I could see this being really handy if you want to test out whether a given range works with various versions.

You can use node's builtin readline module to do this.

[isaacs]

Oh, I just realized something about this.

This means that any programs that spawn('semver') are going to hang until stdin is closed.

That's probably surprising. One approach would be to only read the stdin pipe if - is passed as an argument.

[wraithgar]

Closing this one for now since it still has work to be done.