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features.js
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features.js
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import { hasDecorators } from "./decorators";
export const FEATURES = Object.freeze({
//classes: 1 << 0,
fields: 1 << 1,
privateMethods: 1 << 2,
decorators: 1 << 3,
});
// We can't use a symbol because this needs to always be the same, even if
// this package isn't deduped by npm. e.g.
// - node_modules/
// - @babel/plugin-class-features
// - @babel/plugin-proposal-decorators
// - node_modules
// - @babel-plugin-class-features
const featuresKey = "@babel/plugin-class-features/featuresKey";
const looseKey = "@babel/plugin-class-features/looseKey";
export function enableFeature(file, feature, loose) {
// We can't blindly enable the feature because, if it was already set,
// "loose" can't be changed, so that
// @babel/plugin-class-properties { loose: true }
// @babel/plugin-class-properties { loose: false }
// is transformed in loose mode.
// We only enabled the feature if it was previously disabled.
if (!hasFeature(file, feature)) {
file.set(featuresKey, file.get(featuresKey) | feature);
if (loose) file.set(looseKey, file.get(looseKey) | feature);
}
}
function hasFeature(file, feature) {
return !!(file.get(featuresKey) & feature);
}
export function isLoose(file, feature) {
return !!(file.get(looseKey) & feature);
}
export function verifyUsedFeatures(path, file) {
if (hasFeature(file, FEATURES.decorators)) {
throw new Error(
"@babel/plugin-class-features doesn't support decorators yet.",
);
}
if (hasFeature(file, FEATURES.privateMethods)) {
throw new Error(
"@babel/plugin-class-features doesn't support private methods yet.",
);
}
if (hasDecorators(path) && !hasFeature(file, FEATURES.decorators)) {
throw path.buildCodeFrameError("Decorators are not enabled.");
}
if (path.isProperty()) {
if (!hasFeature(file, FEATURES.fields)) {
throw path.buildCodeFrameError("Class fields are not enabled.");
}
}
}