apple2js/js/types.ts
2022-05-10 08:04:20 -07:00

118 lines
3.3 KiB
TypeScript

/**
* Extracts the members of a constant array as a type. Used as:
*
* @example
* const SOME_VALUES = ['a', 'b', 1, 2] as const;
* type SomeValues = MemberOf<typeof SOME_VALUES>; // 'a' | 'b' | 1 | 2
*/
export type MemberOf<T extends ReadonlyArray<unknown>> =
T extends ReadonlyArray<infer E> ? E : never;
/**
* Recursively extracts all members of a constant array as a type. Used as:
*
* @example
* const SOME_ARRAYS = [['a'],['b', 2], 3] as const;
* type SomeArrayValues = DeepMemberOf<typeof SOME_ARRAYS>; // 'a' | 'b' | 2 | 3
*/
export type DeepMemberOf<T extends ReadonlyArray<unknown>> =
T extends ReadonlyArray<infer E>
? (E extends ReadonlyArray<unknown> ? DeepMemberOf<E> : E)
: never;
/**
* Extracts the declared keys of a type by removing `string` and `number`.
*
* Cribbed from the interwebs:
* https://github.com/microsoft/TypeScript/issues/25987#issuecomment-408339599
*/
export type KnownKeys<T> = {
[K in keyof T]: string extends K ? never : number extends K ? never : K
} extends { [_ in keyof T]: infer U } ? U : never;
/**
* Extracts the declared values of a constant object.
*/
export type KnownValues<T> = T extends {
[_ in keyof T]: infer U } ? U : never;
/**
* Replacement for `includes` on constant types that is also a type assertion.
*
* @example
* const SOME_VALUES = [1, 2, 'a'] as const;
* let n: number = 1;
* let r = includes(SOME_VALUES, n); // r === true, n is 1 | 2 | 'a'
* n = 5;
* r = includes(SOME_VALUES, n); // r === false, n is number
*/
export function includes<S extends T, T>(a: ReadonlyArray<S>, v: T): v is S {
return (a as ReadonlyArray<T>).includes(v);
}
/** A bit. */
export type bit = 0 | 1;
/** A nibble. */
export type nibble =
0x0 | 0x1 | 0x2 | 0x3 | 0x4 | 0x5 | 0x6 | 0x7 |
0x8 | 0x9 | 0xa | 0xb | 0xc | 0xd | 0xe | 0xf;
/** A byte (0..255). This is not enforced by the compiler. */
export type byte = number;
/** A word (0..65535). This is not enforced by the compiler. */
export type word = number;
/** A raw region of memory. */
export type memory = Uint8Array;
/** A raw region of memory. */
export type rom = ReadonlyUint8Array;
export interface Memory {
/** Read a byte. */
read(page: byte, offset: byte): byte;
/** Write a byte. */
write(page: byte, offset: byte, value: byte): void;
}
/** A mapped region of memory. */
export interface MemoryPages extends Memory {
/** Start page. */
start(): byte;
/** End page, inclusive. */
end(): byte;
}
/* An interface card */
export interface Card extends Memory, Restorable {
/* Reset the card */
reset?(): void;
/* Draw card to canvas */
blit?(): ImageData | undefined;
/* Process period events */
tick?(): void;
/* Read or Write an I/O switch */
ioSwitch(off: byte, val?: byte): byte | undefined;
}
export type TapeData = Array<[duration: number, high: boolean]>;
export interface Restorable<T = any> {
getState(): T;
setState(state: T): void;
}
// Read-only typed arrays for constants
export type TypedArrayMutableProperties = 'copyWithin' | 'fill' | 'reverse' | 'set' | 'sort';
export interface ReadonlyUint8Array extends Omit<Uint8Array, TypedArrayMutableProperties> {
readonly [n: number]: number;
}
// Readonly RGB color value
export type Color = readonly [r: byte, g: byte, b: byte];