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overlookmotel
a4478e960a
Add `oxc-codegen` package - a printer written in TS. ### Features - Prints JS, JSX, TS, TSX. - Matches `oxc_codegen` exactly on all Test262, TypeScript, Acorn-JSX fixtures. - Very fast. ### Deficiencies - Pretty-printing only (no compact/minified output). - No support for printing comments. - Source map support is semi-there, but largely untested, and poor API (design doc has some ideas on how to improve it). ### This PR adds - The printer code. - Conformance testing infra. - Further tests for edge cases. - README. - Design doc - how it differs from `oxc_codegen` and why, what produces the perf. ### This PR doesn't add - Not integrated into CI or release pipeline. ### Notes This started as a slop port of `oxc_codegen`. I've iterated on that base, cleaned it up a lot, and at least skimmed through all of it. I think it's in fairly decent shape. The design doc is I think worth a read. It explains the rationale for the choices, in particular the "1 codebase, 4 builds" approach. I've put it in a new top-level directory called `packages`. It's not an app, so didn't seem to me to fit alongside `apps/oxlint` and `apps/oxfmt`. It's pure JS, so not like e.g. `napi/parser`. And it felt too heavyweight to put into `npm` dir. But maybe there's a better place for it. Co-authored-by: Cameron <cameron.clark@hey.com>
72 lines
2.4 KiB
TypeScript
72 lines
2.4 KiB
TypeScript
import type { Plugin } from "rolldown";
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/**
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* Plugin to remove the TypeScript-only regions of `print.ts` from the JS-only builds.
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*
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* The `TS` build-time constant (see `src-js/globals.d.ts`) lets the minifier drop TS-only code
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* in expression positions - `if (TS && node.declare)` folds to nothing when `TS` is `false`.
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* But `case "TSEnumDeclaration":` switch arms are not expressions, and no minifier can remove an arm
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* on the grounds that its node type never occurs. Those arms are fenced with `IF TS` / `END_IF`
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* block-comment markers (the same convention as the raw transfer deserializer builds):
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*
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* ```ts
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* /* IF TS *\/
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* case "TSEnumDeclaration":
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* ...
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* break;
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* /* END_IF *\/
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* ```
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*
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* (`*\/` escapes above only because this is itself a block comment.)
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*
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* This plugin deletes everything from each `IF TS` marker line through its `END_IF` marker line.
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* Once the arms are gone, the TS-only printer functions they called lose their last references,
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* and tree-shaking removes them wholesale.
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*
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* It's a plain text transform (the fences are only visible in source text), so it must run before
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* the AST-based plugins in the plugin list, and only in builds where `TS` is `false`.
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*/
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const REGION = /[ \t]*\/\* IF TS \*\/\n[\s\S]*?\/\* END_IF \*\/\n/g;
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// A factory, so each build counts its own regions rather than sharing a total with the others
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const stripTsPlugin = (): Plugin => {
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let strippedRegions = 0;
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return {
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name: "strip-ts",
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buildStart() {
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strippedRegions = 0;
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},
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transform: {
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// Only process TS files in `src-js/print` directory
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filter: { id: /\/src-js\/print\/.+\.ts$/ },
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handler(code) {
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code = code.replace(REGION, () => {
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strippedRegions++;
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return "";
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});
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// Unbalanced or nested fences leave a marker behind.
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// Most files have no fences at all, so the "did this plugin do anything" check is per build, in `buildEnd`.
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if (code.includes("IF TS") || code.includes("END_IF")) {
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throw new Error("strip-ts: unbalanced or nested `/* IF TS */` / `/* END_IF */` fences");
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}
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return code;
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},
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},
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buildEnd() {
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// No fences anywhere means they have been lost and this plugin is silently doing nothing
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if (strippedRegions === 0) {
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throw new Error("strip-ts: no `/* IF TS */` / `/* END_IF */` fences found");
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}
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},
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};
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};
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export default stripTsPlugin;
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