chore(views): refactor views system to store absolute paths

[ewinslow]

TODOs:

• Add tests for global code that depends on this service.
• Add tests for integration with simplecache
• Remove special-case for core views in getViewLocation
• Update dev tools view inspector to handle the new way views paths are stored.
• Throw \IllegalArgumentException for invalid viewtypes so we don't need so many null checks

Testdox output:

Elgg\Views\Registry

• Registers php files as views
• Registers static files as views
• Get or create viewtype always returns the same instance for the same string
• Current viewtype is the explicitly set viewtype if provided
• Current viewtype falls back to the view input parameter if an explicit viewtype was not set
• Current viewtype falls back to the db configured default if an input parameter was not provided
• Current viewtype falls back to default if no other value was provided
• Views are rendered with the current viewtype by default
• Views are rendered with the specified viewtype as long as it is valid
• Views are not rendered recursively with a specified viewtype if that viewtype is not the current one
• Specified vars are available to views in the vars array
• Global config being available via the vars array is deprecated
• Current user being available via the vars array is deprecated
• Site url being available via the vars array is deprecated

Elgg\Views\View

• Uses php to render non static views
• Does not use php to render static views
• Can register views as cacheable
• Static views are always cacheable
• Can extend views
• Extending a view with priority less than 500 prepends extension content
• Extending a view without a specified priority appends extension content
• Extending a view with priority greater than or equal to 500 appends extension content
• Unextending a view removes the effect of a previous extension
• Unextending a view has no effect on subsequent extensions
• Views can be extended twice by the same view
• Views extended twice by the same view need to be unextended twice to remove those extensions
• Views can exist based on viewtype fallback
• Views can exist based on extension

Elgg\Views\Viewtype

• Viewtypes can fall back

This is a major refactoring of Elgg_ViewsService to remove global state and prep for #6844 (and #3737 to a lesser extent). I know for sure that the global functions are broken as a result of this, but we don't have tests for them. Looking for early feedback, especially in regard to what tests we can add.

DO NOT MERGE

[ewinslow]

I'm submitting this against 1.x even though this is technically an internal refactor because I am not confident about our test coverage. Main priority here IMO is getting more tests so all behaviors are covered and we can make this change with confidence.

[mrclay]

IMO bad place to use a ternary.

[ewinslow]

Can change to:

if (!isset($this->config->template_handler) ||
    !is_callable($this->config->template_handler)) {
  return '';
}

return $this->config->template_handler;

[mrclay]

Besides making dependencies explicit and moving view storage out of $CONFIG, does this do anything else big?

[ewinslow]

It stores absolute paths to each view instead of just storing the directory where the view can be found.

We'll need to update developer tools and possibly simplecache to handle that.

[ewinslow]

The latest iteration of this has the following changes:

• Created a new Elgg\Views namespace and moved the service there.
• Created a View model class that contains some single-view-specific logic
• Created a Viewtype class that contains logic for validating views + storing fallbacks

The View and Viewtype classes are the cleanest now, and the Service contains:

• all the string->instance mappings
• deprecation cruft
• mapping from view names to view instances
• plugin hook triggers

View instances don't know about their names at all. Viewtypes still do, though.

[ewinslow]

Pushed another update that renames Service to Registry. I find the latter more descriptive. Also fixes most of the existing tests.

[ewinslow]

Replaced by #8390