Add filter to $output before it is cached

[jl-a]

Related:

• Filter $output after render and before it is cached #2908

Issue

When filtering $output with timber/output the result is not cached. This is inefficient if the filter being applied is deterministic based on $output content, because the filter results could also be cached rather than being run every time.

Solution

This pull request adds another filter, timber/output/pre-cache, immediately after the template is rendered and before the $output is cached. If this filter is used, then its results will be cached.

Impact

This pull request is backwards compatible, and does not break any existing uses of timber/output. The apply_filters call may add a tiny bit of overhead to each render (not including the actual filter, if any are added) , but overall this could be considered negligible.

Usage Changes

No changes to how Timber is used, other than an additional filter.

Considerations

Testing

No tests needed.

[coveralls]

coverage: 87.914% (-0.8%) from 88.741%
when pulling c417ecc on jl-a:2.x
into a602ec5 on timber:2.x.

[nlemoine]

Looks all good thanks @jl-a!