mirror of
https://github.com/swc-project/swc.git
synced 2024-11-28 02:29:04 +03:00
152 lines
3.3 KiB
Markdown
152 lines
3.3 KiB
Markdown
# swc architecture
|
|
|
|
This document gives a high level overview of swc internals. You may find it useful if you want to contribute to swc or if you are interested in the inner workings of swc.
|
|
|
|
## Macros
|
|
|
|
See [blog post about swc macros](https://swc.rs/blog/2020/01/04/pmutil#macros-built-with-pmutil).
|
|
|
|
swc uses proc macro extensively to reduce work. Please see links below to know what each macro do.
|
|
|
|
- [enum_kind][]
|
|
- [string_enum][]
|
|
- [ast_node][]
|
|
|
|
And some adhoc-macros are used.
|
|
|
|
- [parser_macros][]
|
|
- [codegen_macros][]
|
|
|
|
These macro breaks macro hygiene.
|
|
|
|
## Structure
|
|
|
|
### `/atoms`
|
|
|
|
Handle string interning for the swc project. The crate depends on [string_cache](https://github.com/servo/string-cache) from servo.
|
|
|
|
### `/common`
|
|
|
|
Contains code related to span, hygiene and error reporting.
|
|
|
|
Also, it contains / re-exports codes for visitor pattern. `Visit<T>` is non-mutating visitor, while `Fold<T>` is a mutating visitor.
|
|
|
|
### `/ecmascript/ast`
|
|
|
|
Contains ast nodes for javascript and typescript.
|
|
|
|
### `/ecmascript/codegen`
|
|
|
|
Converts javascript ast into javascript code.
|
|
|
|
### `/ecmascript/parser`
|
|
|
|
Parses javascript and typescript
|
|
|
|
### `/ecmascript/transforms`
|
|
|
|
Theres are three core transforms named `resolver`, `hygiene`, `fixer`. Other transforms depends on them.
|
|
|
|
#### `/ecmascript/transforms/src/resolver`
|
|
|
|
This pass resolves and marks all identifiers in the file.
|
|
|
|
e.g.
|
|
|
|
```js
|
|
let a = 1;
|
|
{
|
|
let a = 1;
|
|
}
|
|
```
|
|
|
|
becomes
|
|
|
|
```js
|
|
let a#0 = 1;
|
|
{
|
|
let a#1 = 1;
|
|
}
|
|
```
|
|
|
|
where number after `#` denotes the hygiene id. If two identifiers have same symbol but different hygiene id, it's different.
|
|
|
|
#### `/ecmascript/transforms/src/hygiene`
|
|
|
|
Hygiene pass actually changes symbol of identifiers with same symbol but different hygiene id.
|
|
|
|
```js
|
|
let a#0 = 1;
|
|
{
|
|
let a#1 = 2;
|
|
}
|
|
```
|
|
|
|
becomes
|
|
|
|
```js
|
|
let a = 1;
|
|
{
|
|
let a1 = 2;
|
|
}
|
|
```
|
|
|
|
#### `/ecmascript/transforms/src/fixer`
|
|
|
|
Fixes borken ast. This allow us to simply fold types like `BinExpr` without caring about operator precedence.
|
|
|
|
It means,
|
|
|
|
```rust
|
|
let v = BinExpr {
|
|
left: "1 + 2",
|
|
op: "*",
|
|
right: "3",
|
|
};
|
|
```
|
|
|
|
(other passes generates ast like this)
|
|
|
|
is converted into
|
|
|
|
```rust
|
|
let v = BinExpr {
|
|
left: "(1 + 2)",
|
|
op: "*",
|
|
right: "3",
|
|
};
|
|
```
|
|
|
|
and printed as
|
|
|
|
```js
|
|
(1 + 2) * 3;
|
|
```
|
|
|
|
#### `/ecmascript/transforms/src/compat`
|
|
|
|
Contains codes related to converting new generation javascript codes for old browsers.
|
|
|
|
#### `/ecmascript/transforms/src/modules`
|
|
|
|
Contains code related to transforming es6 modules to other modules.
|
|
|
|
#### `/ecmascript/transforms/src/optimization`
|
|
|
|
Contains code related to making code faster on runtime. Currently only small set of optimization is implemented.
|
|
|
|
## Tests
|
|
|
|
swc uses [official ecmascript conformance test suite called test262][test262] for testing.
|
|
|
|
Parser tests ensures that parsed result of test262/pass is identical with test262/pass-explicit.
|
|
|
|
Codegen tests ensures that generated code is equivalent to goldened reference files located at [tests/references](ecmascript/codegen/tests/references).
|
|
|
|
[enum_kind]: https://rustdoc.swc.rs/enum_kind/derive.Kind.html
|
|
[string_enum]: https://rustdoc.swc.rs/string_enum/derive.StringEnum.html
|
|
[ast_node]: https://rustdoc.swc.rs/ast_node/index.html
|
|
[parser_macros]: https://rustdoc.swc.rs/swc_ecma_parser_macros/index.html
|
|
[codegen_macros]: https://rustdoc.swc.rs/swc_ecma_codegen_macros/index.html
|
|
[test262]: https://github.com/tc39/test262
|