Implement NgOnChangesFeature, ViewContainerRef, TemplateRef,
and the renderEmbeddedTemplate instruction, and wire together the
pieces required for the ngForOf directive to work.
PR Close#21430
To prepare for pending ngForOf work, the dep from instructions -> query
should be broken. This will enable a dep from di -> instructions while
avoiding a di -> instructions -> query -> di cycle.
Analyzing this cycle also uncovered another problem: the implementation
of query() breaks tree-shaking through a hard dependency on DI concepts
of TemplateRef, ElementRef, ViewContainerRef. This is fundamentally due
to how query() can query for those values without any configuration.
Instead, this fix introduces the concept by employing the strategy
pattern, and redefining QueryReadType to pass a function which will
return one of the above values. This strategy is then used for 'read'
instead of an enum in cases where special values should be read from
the DI system.
PR Close#21430
This change makes the code cleaner for the user. It does mean
a little bit more work for us since we have to patch the `type` back
into the `DirectiveDef`. However since the patching happens only once
on startup it should not be significant.
PR Close#21374
We used to have a separate `directive` instruction for instantiating
directives. However, such an instruction requires that directives
are created in the correct order, which would require that template
compiler would have knowledge of all dependent directives. This
would break template compilation locality principle.
This change only changes the APIs to expected form but does
not change the semantics. The semantics will need to be corrected
in subsequent commits. The semantic change needed is to
resolve the directive instantiation error at runtime based on
injection dependencies.
PR Close#21374
