85 lines
2.9 KiB
TypeScript
85 lines
2.9 KiB
TypeScript
/* A Dispatcher is a collection of operations that do run-time
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* dispatch on the types of their arguments. Thus, every individual
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* method is like a typed-function (from the library by that name),
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* but they can depend on one another and on ona another's implementations
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* for specific types (including their own).
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*/
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import {parseReflectedType, ImplementationDef} from './parseReflectedType.js'
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// First helper types and functions for the Dispatcher
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type TypeName = string
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type Parameter = TypeName
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type Signature = Parameter[]
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type DependenciesType = Record<string, Function>
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// A "canned" dependency for a builtin function:
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export type typeOfDependency = {typeOf: (x: unknown) => TypeName}
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// Utility needed in type definitions
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//dummy implementation for now
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export function joinTypes(a: TypeName, b: TypeName) {
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if (a === b) return a
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return 'any'
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}
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// Now types used in the Dispatcher class itself
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type TypeSpecification = {
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name: string, // just until we get reflection, then we can remove this property
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before?: TypeName[],
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test: ((x: unknown) => boolean)
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| ((d: DependenciesType) => (x: unknown) => boolean),
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from: Record<TypeName, Function>,
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infer?: (d: DependenciesType) => (z: unknown) => TypeName
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}
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type SpecObject = Record<string, Function | TypeSpecification>
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type SpecificationsGroup = Record<string, SpecObject>
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export class Dispatcher {
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installSpecification(
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name: string,
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defn: ImplementationDef,
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behavior: Function // possible todo: constrain this type based
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// on the signature, return type, and dependencies. Not sure if
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// that's really possible, though.
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) {
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console.log('Pretending to install', name, 'with signatures')
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for (const signature of defn.fn.signatures) {
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console.log(' ', signature.args, '=>', signature.returns)
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}
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if (defn.fn.aliasOf) {
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console.log(' As an alias of', defn.fn.aliasOf)
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}
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//TODO: implement me
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}
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installType(name: TypeName, typespec: TypeSpecification) {
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console.log('Pretending to install type', name, typespec)
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//TODO: implement me
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}
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constructor(collection: SpecificationsGroup) {
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const implementations = []
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for (const key in collection) {
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console.log('Working on', key)
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for (const identifier in collection[key]) {
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const item = collection[key][identifier]
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if (typeof item === 'function') {
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implementations.push([key, identifier, item])
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} else {
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console.log('Handling type', key, ':', identifier)
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this.installType(
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item.name, collection[key][identifier] as TypeSpecification)
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}
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}
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}
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for (const trio of implementations) {
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const [k, id, imp] = trio
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console.log('Handling implementation', id, 'from', k)
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this.installSpecification(
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id, parseReflectedType(id, imp.reflectedType), imp)
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}
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}
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}
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