Depreciate regular expressions for copy's filter

[martinheidegger]

Regular Expression filters in ncp.js:38 are run against the full source path, i.e.:

/Users/martin/Private/projects/nodeschool/git-it-electron/node_modules/eslint/node_modules/uglify-js/node_modules/source-map/lib/util.js

If I want in the folder git-it-electron to exclude the eslint folder I need to know that I am in the /Users/martin/Private/projects/nodeschool/git-it-electron folder when I do that. If I test for /eslint/ then It would exclude the folder properly but If by some accident I would put the project in a folder called:

/Users/eslint/Private/projects/nodeschool/git-it-electron

It would ignore all of the files in my project 😢 . This means that someone would need to implement the file matching with that in mind. Given that ncp.js already considers the working directory I think it would be specially awesome if

A. there would be the opportunity to have filters that work relatively to the working directory
B. there would be the opportunity to specify where the working directory is (overriding the good process.cwd() default)

Additionally it would be super awesome if the filter would allow glob file patterns instead of regexp patterns because they are made for files.

Note: I am thinking about the API a little and think it would be good to have an include and exclude option instead of filters. (Considering #65)

[jprichardson]

What if the RegExp's were deprecated and you just passed a function {filter: function() { }}... this way you could use glob?

[jprichardson]

FYI, functions are supported now.

[martinheidegger]

They are supported but they don't know the base path. A deprecation might
be worth thinking about. Also it might be worth to specify the filter API
to be directly compatible with glob in order for the filter to work like
this: include: glob.bind(null, "**/*.js"). I could also think an API like
include: require("fs-extra/pattern")("**/*.js") might be good.

[RyanZim]

@jprichardson ping?

[jprichardson]

I'd prefer only functions, but I'm afraid that it'll break a lot of code. Long-term, this should use file glob patterns with another module like glob. So we should at least deprecate the Regex version for 1.0.0.

Thoughts?

[RyanZim]

@jprichardson Migration from regexes is simple:

- /somereg.*/
+ /somereg.*/.test

Edit: Incorrect, you will lose the this binding for test. Must do (using arrow functions):

s => /somereg.*/.test(s)

If you want to depreciate, go ahead.