f9b13e4e58
When HMR is enabled, we need to capture the dependencies used in a template and forward them to the HMR replacement function. One half of this process is static, meaning that we can't change it after the initial compilation. Tree shaking becomes a problem in such a case, because the user can change the template in a way that changes the set of dependencies which will start matching with the static part of the HMR code. These changes disable the tree shaking when HMR is enabled to ensure that the dependencies stay stable. Fixes #59581. PR Close #59595 |
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| common | ||
| component | ||
| directive | ||
| ng_module | ||
| src | ||
| test | ||
| BUILD.bazel | ||
| index.ts | ||
| README.md | ||
What is the 'annotations' package?
This package implements compilation of Angular-annotated classes - those with @Component, @NgModule, etc. decorators. (Note that the compiler uses 'decorator' and 'annotation' interchangeably, despite them having slightly different semantics).
The 'transform' package of the compiler provides an abstraction for a DecoratorHandler, which defines how to compile a class decorated with a particular Angular decorator. This package implements a DecoratorHandler for each Angular type. The methods of these DecoratorHandlers then allow the rest of the compiler to process each decorated class through the phases of compilation.
Anatomy of DecoratorHandlers
Each handler implemented here performs some similar operations:
- It uses the
PartialEvaluatorto resolve expressions within the decorator metadata or other decorated fields that need to be understood statically. - It extracts information from constructors of decorated classes which is required to generate dependency injection instructions.
- It reports errors when developers have misused or misconfigured the decorators.
- It populates registries that describe decorated classes to the rest of the compiler.
- It uses those same registries to understand decorated classes within the context of the compilation (for example, to understand which dependencies are used in a given template).
- It creates
SemanticSymbols which allow for accurate incremental compilation when reacting to input changes. - It builds metadata objects for
@angular/compilerwhich describe the decorated classes, which can then perform the actual code generation.
Since there is significant overlap between DecoratorHandler implementations, much of this functionality is implemented in a shared 'common' sub-package.