Currently the ImportManager class handles various rewriting actions of
imports when compiling @angular/core. This is required as code compiled
within @angular/core cannot import from '@angular/core'. To work around
this, imports are rewritten to get core symbols from a particular file,
r3_symbols.ts.
In this refactoring, this rewriting logic is moved out of the ImportManager
and put behind an interface, ImportRewriter. There are three implementers
of the interface:
* NoopImportRewriter, used for compiling all non-core packages.
* R3SymbolsImportRewriter, used when ngtsc compiles @angular/core.
* NgccFlatImportRewriter, used when ngcc compiles @angular/core (special
logic is needed because ngcc has to rewrite imports in flat bundles
differently than in non-flat bundles).
This is a precursor to using this rewriting logic in other contexts besides
the ImportManager.
PR Close#27998
This refactoring moves code around between a few of the ngtsc subpackages,
with the goal of having a more logical package structure. Additional
interfaces are also introduced where they make sense.
The 'metadata' package formerly contained both the partial evaluator,
the TypeScriptReflectionHost as well as some other reflection functions,
and the Reference interface and various implementations. This package
was split into 3 parts.
The partial evaluator now has its own package 'partial_evaluator', and
exists behind an interface PartialEvaluator instead of a top-level
function. In the future this will be useful for reducing churn as the
partial evaluator becomes more complicated.
The TypeScriptReflectionHost and other miscellaneous functions have moved
into a new 'reflection' package. The former 'host' package which contained
the ReflectionHost interface and associated types was also merged into this
new 'reflection' package.
Finally, the Reference APIs were moved to the 'imports' package, which will
consolidate all import-related logic in ngtsc.
PR Close#27743
In Ivy, a pure call to `setClassMetadata` is inserted to retain the
information that would otherwise be lost while eliding the Angular
decorators. In the past, the Angular constructor decorators were
wrapped inside of an anonymous function which was only evaluated once
`ReflectionCapabilities` was requested for such metadata. This approach
prevents forward references from inside the constructor parameter
decorators from being evaluated before they are available.
In the `setClassMetadata` call, the constructor parameters were not wrapped
within an anonymous function, such that forward references were evaluated
too early, causing runtime errors.
This commit changes the `setClassMetadata` call to pass the constructor
parameter decorators inside of an anonymous function again, such that
forward references are not resolved until requested by
`ReflectionCapabilities`, therefore avoiding the early reads of forward refs.
PR Close#27561
This commit introduces generateSetClassMetadataCall(), an API in ngtsc
for generating calls to setClassMetadata() for a given declaration. The
reflection API is used to enumerate Angular decorators on the declaration,
which are converted to a format that ReflectionCapabilities can understand.
The reflection metadata is then patched onto the declared type via a call
to setClassMetadata().
This is simply a utility, a future commit invokes this utility for
each DecoratorHandler.
Testing strategy: tests are included which exercise generateSetClassMetadata
in isolation.
PR Close#26860
