Added alt-function to support RetinaJS libraries.

[mblarsen]

This pull requests implements an alt(ernative) option. This options will allow to map the hash prefix from an original file - say logo.png => ab47.logo.png - onto alternative versions of that file - say logo@2x.png => ab47.logo@2x.png.

This is useful when you are working with retina images, that require the files to named identically except for some part of the filename, for example @2x.

Request included passing unit tests.

[steveluscher]

Continuing discussion from #15

Neat!

One bug and one API suggestion.

Bug: We must calculate the hash of the group of files. If I change one image or the other, the hash should change.

API suggestion: In my opinion, calculating a groupwise hash on files with the “@\dx” or “_\dx” suffix should be the default. Files will not likely get named as such by coincidence. Hence, I think the only option we need to add is a pattern, that when matched and eliminated, maps to some “root” filename.

Given this:

rev: {
  options: {
    // Default. RegExp or array of RegExps.
    // Matches @2x, _3x, @4x, _5x, etc…
    alternatesPattern: /[@_]\dx/
  },
  files: {
    src: ['**/*.{js,css,png,jpg}']
  }
}

The following filenames:

 image.jpg
 image@2x.jpg
 image@4x.jpg

…will map to this “root” filename:

image.jpg

All files in the group should then get hashed together to produce:

 {hash}.image.jpg
 {hash}.image@2x.jpg
 {hash}.image@4x.jpg

[mblarsen]

Good points. I'll add these changes.

[mblarsen]

I'll add an option to turn of handling of alternates.

[mblarsen]

I purposely used globs in stead of regexp, because I thought it would be easier for most. But the solution would be easier just using regexp.

I'm kind of for simplifying the solution.

Cons:

• Slightly more complicated with regexp than globs
• No separate pattern for matching alternates (will match all matching regexp)
• Only one pattern of alternates, but most users will have only one, anyway and it could be expressed with pipe-sign.

Pros:

• simpler config
• less dependencies

[mblarsen]

Check the new implementation. Works as to your specs.

[steveluscher]

Cool.

If it were me, I'd still have /[@_]\d+x/ be the default alternatesPattern, and I would not offer a flag for turning alternates on or off – simply set alternatesPattern to null to disable grouping.

alternatesPattern: /[@_]\d+x/            // Default
alternatesPattern: [/-hover/, /-active/] // An array of patterns
alternatesPattern: null                  // Turn alternate matching off    

Again, just so everyone's clear, the role of the pattern is to produce a match which, when removed from the filename, produces some ‘base’ filename that a group of alternates share in common. Those member files then get hashed as a group and the same hash gets applied to all of the files in the group.

So…

image.jpg
image-hover.jpg
image-active.jpg

…would all produce the base filename image.jpg after the matches produced by [/-hover/, /-active/] are removed.

[mblarsen]

I've removed alternates: true|false and replaced it with alternatesPattern: null

The reset worked already. Added test to show default case. There are not tests for array.

Note that [/-hover/, /-active/] can be achieved by /-(hover|active)/ as well, but some times it can make it more readable to split it up.

[steveluscher]

Neat. Now we just need to get @cbas' opinion.

[mblarsen]

Come to think of it. In the current implementation the array option is seen as patterns describing separate groups alternates - different schemes you could say:

alternatesPattern: [ /-hover/, /-active/ ]

Where as:

 alternatesPattern: [ /-(hover|active)/ ] // .. or
 alternatesPattern: /-(hover|active)/

Will would describe only one pattern of alternates.

A more practical use of array would be:

alternatesPattern: [ /-(hover|active)/, /[@_]\dx/ ]

The current implementation fails if two patterns matches the same file. An example

logo.png               // matched by both
logo-hover.png
logo-action.png
logo_2x.png
logo_4x.png

In real life I guess your pattern would be:

alternatesPattern: /-(hover|active)[@_]d\x/

[mblarsen]

Just to let you know. We are using this problem free in production now.@cbas @steveluscher

[steveluscher]

:+1:

[thiagofesta]

:+1: I'd love to see it merged in and released as a new version... What we are waiting for? @cbas @steveluscher @mblarsen

[steveluscher]

I'm down, but I don't have write access to this repo. If this PR looks good to @cbas, it looks good to me!

[thiagofesta]

@cbas is not merging it, so for who wants to use it, replace grunt-rev with this one:

"grunt-rev": "https://github.com/TinyCarrier/grunt-rev/tarball/c8714c9a21ffd107c72a2a2db64cda9cfcd59f37"