100 lines
4.0 KiB
TypeScript
100 lines
4.0 KiB
TypeScript
import type {Dependencies, Signature} from '../interfaces/type.js'
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import {$$typeToString, $$ts, $$define, $$raw, $$ident, $$escape} from 'ts-macros'
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import * as ts from 'typescript'
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export const square =
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<T>(dep: Dependencies<'multiply', T>): Signature<'square', T> =>
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z => dep.multiply(z, z)
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// z => dep.fooBar(z, z) // fails as desired
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// z => dep.multiply(z, 'foo') // still fails as desired
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// make sure ts-macros is running
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function $contains<T>(value: T, ...possible: Array<T>) {
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// repetition which goes over all the elements in the "possible" array
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return +["||", [possible], (item: T) => value === item];
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}
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const searchItem = "needle";
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console.log("In generic arithmetic")
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console.log($contains!(searchItem, "erwin", "tj"));
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// Transpiles to: console.log(false);
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// OK, record the type of square:
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square.reflectedType = //$$typeToString!<typeof square>();
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$$typeToString!<
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<T>(...args: DeepExpand<Parameters<typeof square<T>>>)
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=> DeepExpand<ReturnType<typeof square<T>>>
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>()
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type ShallowExpand<T> = T extends unknown ? { [K in keyof T]: T[K] } : never;
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// Short alias of ShallowExpand for convenience below:
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type Deps<T> = T extends unknown ? { [K in keyof T]: T[K] } : never;
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type ExpandedParameters<T extends (...args: any) => any> = {[Index in keyof Parameters<T>]: ShallowExpand<Parameters<T>[Index]>}
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type ExpandTwice<T extends any[]> = {[Index in keyof T] : ShallowExpand<T[Index]>}
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type AsArray<T> = T extends any[] ? T : [];
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type DeepExpand<T> =
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T extends (...args: any) => any
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? (...pars: AsArray<DeepExpand<Parameters<T>>>) => DeepExpand<ReturnType<T>> :
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T extends unknown ? { [K in keyof T]: DeepExpand<T[K]> } : never;
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type Out<T> = ShallowExpand<Dependencies<'multiply', T>>;
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console.log("Deps type is", $$typeToString!<<T>() => Out<T>>())
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type OutB = ExpandTwice<Parameters<typeof square>>;
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console.log("Or perhaps", $$typeToString!<OutB>())
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console.log("Or maybe even", $$typeToString!<
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<T>(...args: DeepExpand<Parameters<typeof square<T>>>) => DeepExpand<ReturnType<typeof square<T>>>
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>())
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// Now try to wrap it up in a macro
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// From the creator of ts-macros; temporary until next release
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function $export(name: string, value: unknown) {
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$$raw!((ctx, name: ts.Expression, value: ts.Expression) => {
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if (!ctx.ts.isStringLiteral(name)) throw ctx.error(name, "Expected a string literal.");
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return [ctx.factory.createVariableStatement([ctx.factory.createToken(ctx.ts.SyntaxKind.ExportKeyword)], ctx.factory.createVariableDeclarationList([
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ctx.factory.createVariableDeclaration(name.text, undefined, undefined, value)
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], ctx.ts.NodeFlags.Const))];
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});
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}
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// Obviously we'd prefer the name before the expression, but that won't work
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// until the next release
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function $exportImpl<Impl>(expr: Impl, name: string) {
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$export!(name, expr);
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$$ident!(name).reflectedType = $$typeToString!<
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// <T>(...args: DeepExpand<Parameters<Impl<T>>>) => DeepExpand<ReturnType<Impl<T>>> // see comment in reflect below.
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Impl
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>();
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}
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// works but then not visible at import with current ts-macros.
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// Author says he will be enhancing this "soon."
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$exportImpl!(<T>(dep: Dependencies<'multiply', T>): Signature<'square', T> =>
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z => dep.multiply(z, z),
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'squire')
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function $reflect<Impl>(expr: Impl) {
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return $$escape!(() => {
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const temp: Impl & {reflectedType?: string} = expr;
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temp.reflectedType = $$typeToString!<
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// <T>(...args: DeepExpand<Parameters<Impl<T>>>) =>
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// DeepExpand<ReturnType<Impl<T>>> // error; can't instantiate
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// Impl; even if we constrain it to be the type of a generic function,
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// that's still not a generic _type_, ugh.
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Impl>();
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return temp;
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}) as Impl & {reflectedType: string}
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}
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export const squre = $reflect!(
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<T>(dep: Dependencies<'multiply', T>): Signature<'square', T> =>
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z => dep.multiply(z, z))
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export const sqre = $reflect!(
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<T>(dep: Deps<Dependencies<'multiply', T>>): Signature<'square', T> =>
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z => dep.multiply(z, z))
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