Files
opencode/packages/core/src/schema.ts
2026-05-11 21:14:55 -04:00

107 lines
3.8 KiB
TypeScript

import { Option, Schema, SchemaGetter } from "effect"
/**
* Integer greater than zero.
*/
export const PositiveInt = Schema.Int.check(Schema.isGreaterThan(0))
/**
* Integer greater than or equal to zero.
*/
export const NonNegativeInt = Schema.Int.check(Schema.isGreaterThanOrEqualTo(0))
/**
* Optional public JSON field that can hold explicit `undefined` on the type
* side but encodes it as an omitted key, matching legacy `JSON.stringify`.
*/
export const optionalOmitUndefined = <S extends Schema.Top>(schema: S) =>
Schema.optionalKey(schema).pipe(
Schema.decodeTo(Schema.optional(schema), {
decode: SchemaGetter.passthrough({ strict: false }),
encode: SchemaGetter.transformOptional(Option.filter((value) => value !== undefined)),
}),
)
/**
* Strip `readonly` from a nested type. Stand-in for `effect`'s `Types.DeepMutable`
* until `effect:core/x228my` ("Types.DeepMutable widens unknown to `{}`") lands.
*
* The upstream version falls through `unknown` into `{ -readonly [K in keyof T]: ... }`
* where `keyof unknown = never`, so `unknown` collapses to `{}`. This local
* version gates the object branch on `extends object` (which `unknown` does
* not) so `unknown` passes through untouched.
*
* Primitive bailout matches upstream — without it, branded strings like
* `string & Brand<"SessionID">` fall into the object branch and get their
* prototype methods walked.
*
* Tuple branch preserves readonly tuples (e.g. `ConfigPlugin.Spec`'s
* `readonly [string, Options]`); the general array branch would otherwise
* widen them to unbounded arrays.
*/
// eslint-disable-next-line @typescript-eslint/ban-types
export type DeepMutable<T> = T extends string | number | boolean | bigint | symbol | Function
? T
: T extends readonly [unknown, ...unknown[]]
? { -readonly [K in keyof T]: DeepMutable<T[K]> }
: T extends readonly (infer U)[]
? DeepMutable<U>[]
: T extends object
? { -readonly [K in keyof T]: DeepMutable<T[K]> }
: T
/**
* Attach static methods to a schema object. Designed to be used with `.pipe()`:
*
* @example
* export const Foo = fooSchema.pipe(
* withStatics((schema) => ({
* zero: schema.make(0),
* from: Schema.decodeUnknownOption(schema),
* }))
* )
*/
export const withStatics =
<S extends object, M extends Record<string, unknown>>(methods: (schema: S) => M) =>
(schema: S): S & M =>
Object.assign(schema, methods(schema))
/**
* Nominal wrapper for scalar types. The class itself is a valid schema —
* pass it directly to `Schema.decode`, `Schema.decodeEffect`, etc.
*
* Overrides `~type.make` on the derived `Schema.Opaque` so `Schema.Schema.Type`
* of a field using this newtype resolves to `Self` rather than the underlying
* branded phantom. Without that override, passing a class instance to code
* typed against `Schema.Schema.Type<FieldSchema>` would require a cast even
* though the values are structurally equivalent at runtime.
*
* @example
* class QuestionID extends Newtype<QuestionID>()("QuestionID", Schema.String) {
* static make(id: string): QuestionID {
* return this.make(id)
* }
* }
*
* Schema.decodeEffect(QuestionID)(input)
*/
export function Newtype<Self>() {
return <const Tag extends string, S extends Schema.Top>(tag: Tag, schema: S) => {
abstract class Base {
declare readonly _newtype: Tag
static make(value: Schema.Schema.Type<S>): Self {
return value as unknown as Self
}
}
Object.setPrototypeOf(Base, schema)
return Base as unknown as (abstract new (_: never) => { readonly _newtype: Tag }) & {
readonly make: (value: Schema.Schema.Type<S>) => Self
} & Omit<Schema.Opaque<Self, S, {}>, "make" | "~type.make"> & {
readonly "~type.make": Self
}
}
}