tmu
02f736507c
`getMatcher` / `getMatcherW` become `getPrimitiveUnionMatcher` / `getPrimitiveUnionMatcherW`; `src/primitive.ts` and its test move to `src/primitive-union.*`. The `Union` suffix mirrors `getTaggedUnionMatcher`.
29 lines
1.2 KiB
TypeScript
29 lines
1.2 KiB
TypeScript
import type { ValueOf } from "type-fest";
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// The primitive-union and tagged-union matchers differ in their universe, but the
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// handler/fallback plumbing is identical; these are the shared pieces. The
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// boundary is deliberate: `Handlers`, `Fallback` and `MustBePartial` stay with
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// each matcher because they are built from its universe. See development/library.md.
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// A handler: one universe member in, one return value out.
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export type UnaryFn<T, R> = (shape: T) => R;
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// `Extract` drops optional handlers (`undefined`) so `PatternReturns` also works
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// when `P`'s constraint has optional keys.
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export type PatternReturns<P> = ReturnType<
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Extract<ValueOf<P>, (...args: never[]) => unknown>
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>;
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// The diagnostic raised when a fallback is supplied for an already-exhaustive
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// handler map. Each matcher's `MustBePartial` folds it into `Handled`'s
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// constraint so the guard is checked after inference.
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export interface RedundantFallback {
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readonly "every case is already handled, so the fallback is redundant": never;
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}
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// The runtime dispatch map the handler maps and fallback erase to.
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export type HandlerMap = Record<
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string | number,
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UnaryFn<never, unknown> | undefined
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>;
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