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Test plan: `git grep -i v3` only shows incidental hits in longer strings `yarn travis --full` passes `yarn backend` works `yarn build` works `yarn start` works `node bin/sourcecred.js start` works `node bin/sourcecred.js load sourcecred example-github` works Paired with @wchargin
46 lines
1.4 KiB
JavaScript
46 lines
1.4 KiB
JavaScript
// @flow
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export opaque type Compatible<T> = [CompatInfo, T];
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type CompatInfo = {|
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+type: string,
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+version: string,
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|};
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export function toCompat<T>(compatInfo: CompatInfo, obj: T): Compatible<T> {
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return [compatInfo, obj];
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}
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/**
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* Load an object from compatibilized state created by `toCompat`.
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* The object has an expected type and version, and may optionally have
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* handler functions for transforming previous versions into a canonical state.
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* If a handler is present for the current version, it will be applied.
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* Throws an error if the compatibilized object is the wrong type, or if its version
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* is not current and there was no handler for its version.
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*/
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export function fromCompat<T>(
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expectedCompatInfo: CompatInfo,
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obj: Compatible<any>,
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handlers: ?{[version: string]: (any) => T}
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): T {
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if (!Array.isArray(obj) || obj.length !== 2) {
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throw new Error(
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"Tried to load object that didn't have compatibility defined"
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);
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}
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const {type, version} = obj[0];
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let result = obj[1];
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const {type: expectedType, version: expectedVersion} = expectedCompatInfo;
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if (type !== expectedType) {
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throw new Error(`Expected type to be ${expectedType} but got ${type}`);
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}
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if (handlers != null && handlers[version] != null) {
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result = handlers[version](result);
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} else if (version !== expectedVersion) {
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throw new Error(`${type}: tried to load unsupported version ${version}`);
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}
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return result;
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}
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