angular-cn/tools/@angular/tsc-wrapped/README.md

# tsc-wrapped

This package is an internal dependency used by @angular/compiler-cli. Please use that instead.

This is a wrapper around TypeScript's `tsc` program that allows us to hook in extra extensions.
TypeScript will eventually have an extensibility model for arbitrary extensions. We don't want
to constrain their design with baggage from a legacy implementation, so this wrapper only
supports specific extensions developed by the Angular team:

- tsickle down-levels Decorators into Annotations so they can be tree-shaken
- tsickle can also optionally produce Closure Compiler-friendly code
- ./collector.ts emits an extra `.metadata.json` file for every `.d.ts` file written, 
  which retains metadata about decorators that is lost in the TS emit
- @angular/compiler-cli extends this library to additionally generate template code

## TypeScript Decorator metadata collector

The `.d.ts` format does not preserve information about the Decorators applied to symbols.
Some tools, such as Angular template compiler, need access to statically analyzable
information about Decorators, so this library allows programs to produce a `foo.metadata.json`
to accompany a `foo.d.ts` file, and preserves the information that was lost in the declaration
emit.

## Releasing
```
$ $(npm bin)/tsc -p tools
$ cp tools/tsc-wrapped/package.json dist/tools/@angular/tsc-wrapped/
$ npm login [angular]
$ npm publish dist/tools/@angular/tsc-wrapped
```