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[fabric/core] Enhance VariantMatcher to support return type parameterization in match function

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This commit is contained in:
Pablo Baleztena 2024-10-15 07:59:35 -03:00
parent 38e23ba095
commit 1886c52ece
1 changed files with 9 additions and 5 deletions
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14
packages/fabric/core/src/variant/match.ts
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@ -1,17 +1,21 @@
import { Fn } from "../types/fn.js"; import { Fn } from "../types/fn.js";
import { TaggedVariant, VariantFromTag, VariantTag } from "./variant.js"; import { TaggedVariant, VariantFromTag, VariantTag } from "./variant.js";
export type VariantMatcher<TVariant extends TaggedVariant<string>> = { export type VariantMatcher<TVariant extends TaggedVariant<string>, T> = {
[K in TVariant[VariantTag]]: Fn<VariantFromTag<TVariant, K>>; [K in TVariant[VariantTag]]: Fn<VariantFromTag<TVariant, K>, T>;
}; };
export function match<const TVariant extends TaggedVariant<string>>( export function match<const TVariant extends TaggedVariant<string>>(
v: TVariant, v: TVariant,
) { ) {
return { return {
case<const TMatcher extends VariantMatcher<TVariant>>( case<
cases: TMatcher, const TReturnType,
): ReturnType<TMatcher[TVariant[VariantTag]]> { const TMatcher extends VariantMatcher<
TVariant,
TReturnType
> = VariantMatcher<TVariant, TReturnType>,
>(cases: TMatcher): TReturnType {
if (!(v[VariantTag] in cases)) { if (!(v[VariantTag] in cases)) {
throw new Error("Non-exhaustive pattern match"); throw new Error("Non-exhaustive pattern match");
} }