178 lines
3.1 KiB
JavaScript
178 lines
3.1 KiB
JavaScript
import { CustomType as $CustomType, isEqual } from "../gleam.mjs";
|
|
|
|
export class Lt extends $CustomType {}
|
|
export const Order$Lt = () => new Lt();
|
|
export const Order$isLt = (value) => value instanceof Lt;
|
|
|
|
export class Eq extends $CustomType {}
|
|
export const Order$Eq = () => new Eq();
|
|
export const Order$isEq = (value) => value instanceof Eq;
|
|
|
|
export class Gt extends $CustomType {}
|
|
export const Order$Gt = () => new Gt();
|
|
export const Order$isGt = (value) => value instanceof Gt;
|
|
|
|
/**
|
|
* Inverts an order, so less-than becomes greater-than and greater-than
|
|
* becomes less-than.
|
|
*
|
|
* ## Examples
|
|
*
|
|
* ```gleam
|
|
* negate(Lt)
|
|
* // -> Gt
|
|
* ```
|
|
*
|
|
* ```gleam
|
|
* negate(Eq)
|
|
* // -> Eq
|
|
* ```
|
|
*
|
|
* ```gleam
|
|
* negate(Gt)
|
|
* // -> Lt
|
|
* ```
|
|
*/
|
|
export function negate(order) {
|
|
if (order instanceof Lt) {
|
|
return new Gt();
|
|
} else if (order instanceof Eq) {
|
|
return order;
|
|
} else {
|
|
return new Lt();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Produces a numeric representation of the order.
|
|
*
|
|
* ## Examples
|
|
*
|
|
* ```gleam
|
|
* to_int(Lt)
|
|
* // -> -1
|
|
* ```
|
|
*
|
|
* ```gleam
|
|
* to_int(Eq)
|
|
* // -> 0
|
|
* ```
|
|
*
|
|
* ```gleam
|
|
* to_int(Gt)
|
|
* // -> 1
|
|
* ```
|
|
*/
|
|
export function to_int(order) {
|
|
if (order instanceof Lt) {
|
|
return -1;
|
|
} else if (order instanceof Eq) {
|
|
return 0;
|
|
} else {
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Compares two `Order` values to one another, producing a new `Order`.
|
|
*
|
|
* ## Examples
|
|
*
|
|
* ```gleam
|
|
* compare(Eq, with: Lt)
|
|
* // -> Gt
|
|
* ```
|
|
*/
|
|
export function compare(a, b) {
|
|
let x = a;
|
|
let y = b;
|
|
if (isEqual(x, y)) {
|
|
return new Eq();
|
|
} else if (a instanceof Lt) {
|
|
return new Lt();
|
|
} else if (a instanceof Eq && b instanceof Gt) {
|
|
return new Lt();
|
|
} else {
|
|
return new Gt();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Inverts an ordering function, so less-than becomes greater-than and greater-than
|
|
* becomes less-than.
|
|
*
|
|
* ## Examples
|
|
*
|
|
* ```gleam
|
|
* import gleam/int
|
|
* import gleam/list
|
|
*
|
|
* list.sort([1, 5, 4], by: reverse(int.compare))
|
|
* // -> [5, 4, 1]
|
|
* ```
|
|
*/
|
|
export function reverse(orderer) {
|
|
return (a, b) => { return orderer(b, a); };
|
|
}
|
|
|
|
/**
|
|
* Return a fallback `Order` in case the first argument is `Eq`.
|
|
*
|
|
* ## Examples
|
|
*
|
|
* ```gleam
|
|
* import gleam/int
|
|
*
|
|
* break_tie(in: int.compare(1, 1), with: Lt)
|
|
* // -> Lt
|
|
* ```
|
|
*
|
|
* ```gleam
|
|
* import gleam/int
|
|
*
|
|
* break_tie(in: int.compare(1, 0), with: Eq)
|
|
* // -> Gt
|
|
* ```
|
|
*/
|
|
export function break_tie(order, other) {
|
|
if (order instanceof Lt) {
|
|
return order;
|
|
} else if (order instanceof Eq) {
|
|
return other;
|
|
} else {
|
|
return order;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Invokes a fallback function returning an `Order` in case the first argument
|
|
* is `Eq`.
|
|
*
|
|
* This can be useful when the fallback comparison might be expensive and it
|
|
* needs to be delayed until strictly necessary.
|
|
*
|
|
* ## Examples
|
|
*
|
|
* ```gleam
|
|
* import gleam/int
|
|
*
|
|
* lazy_break_tie(in: int.compare(1, 1), with: fn() { Lt })
|
|
* // -> Lt
|
|
* ```
|
|
*
|
|
* ```gleam
|
|
* import gleam/int
|
|
*
|
|
* lazy_break_tie(in: int.compare(1, 0), with: fn() { Eq })
|
|
* // -> Gt
|
|
* ```
|
|
*/
|
|
export function lazy_break_tie(order, comparison) {
|
|
if (order instanceof Lt) {
|
|
return order;
|
|
} else if (order instanceof Eq) {
|
|
return comparison();
|
|
} else {
|
|
return order;
|
|
}
|
|
}
|