nelmio/alice — pull request #88 by kalifg (2014-03-06 21:10:30+00:00)
Title: Provider reference passing update

## Background
The ability to pass an entity reference to a provider was added in nelmio/alice#50, however the regex checks for boundaries, which results in limiting these references to a single occurrence. The inside of a provider call can contain arbitrary PHP so this seems unnecessary.

## Implementation
I added 935e138 so that I had a provider available with which I could write a test for 36ba7c5. Otherwise it is no necessary for this fix. However, we have found the `identity` provider incredibly useful paired with the ability to perform simple operations such as math inside the provider call. Some framework was added to support having built-in providers.

It is made more convenient by adding some syntactic sugar, `<()>` is the same as ``.