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Viewing / Editing File: Struct.ts

/**
 * This module provides utility functions for working with structs in TypeScript.
 *
 * @since 2.0.0
 */

import * as Equivalence from "./Equivalence.js"
import { dual } from "./Function.js"
import * as order from "./Order.js"
import * as Predicate from "./Predicate.js"
import type { MatchRecord, Simplify } from "./Types.js"

/**
 * Create a new object by picking properties of an existing object.
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { pipe, Struct } from "effect"
 *
 * assert.deepStrictEqual(pipe({ a: "a", b: 1, c: true }, Struct.pick("a", "b")), { a: "a", b: 1 })
 * assert.deepStrictEqual(Struct.pick({ a: "a", b: 1, c: true }, "a", "b"), { a: "a", b: 1 })
 * ```
 *
 * @since 2.0.0
 */
export const pick: {
  /**
   * Create a new object by picking properties of an existing object.
   *
   * @example
   * ```ts
   * import * as assert from "node:assert"
   * import { pipe, Struct } from "effect"
   *
   * assert.deepStrictEqual(pipe({ a: "a", b: 1, c: true }, Struct.pick("a", "b")), { a: "a", b: 1 })
   * assert.deepStrictEqual(Struct.pick({ a: "a", b: 1, c: true }, "a", "b"), { a: "a", b: 1 })
   * ```
   *
   * @since 2.0.0
   */
  <Keys extends Array<PropertyKey>>(...keys: Keys): <S extends { [K in Keys[number]]?: any }>(
    s: S
  ) => MatchRecord<S, { [K in Keys[number]]?: S[K] }, Simplify<Pick<S, Keys[number]>>>
  /**
   * Create a new object by picking properties of an existing object.
   *
   * @example
   * ```ts
   * import * as assert from "node:assert"
   * import { pipe, Struct } from "effect"
   *
   * assert.deepStrictEqual(pipe({ a: "a", b: 1, c: true }, Struct.pick("a", "b")), { a: "a", b: 1 })
   * assert.deepStrictEqual(Struct.pick({ a: "a", b: 1, c: true }, "a", "b"), { a: "a", b: 1 })
   * ```
   *
   * @since 2.0.0
   */
  <S extends object, Keys extends Array<keyof S>>(s: S, ...keys: Keys): MatchRecord<S, { [K in Keys[number]]?: S[K] }, Simplify<Pick<S, Keys[number]>>>
} = dual(
  (args) => Predicate.isObject(args[0]),
  <S extends object, Keys extends Array<keyof S>>(s: S, ...keys: Keys) => {
    const out: any = {}
    for (const k of keys) {
      if (k in s) {
        out[k] = (s as any)[k]
      }
    }
    return out
  }
)

/**
 * Create a new object by omitting properties of an existing object.
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { pipe, Struct } from "effect"
 *
 * assert.deepStrictEqual(pipe({ a: "a", b: 1, c: true }, Struct.omit("c")), { a: "a", b: 1 })
 * assert.deepStrictEqual(Struct.omit({ a: "a", b: 1, c: true }, "c"), { a: "a", b: 1 })
 * ```
 *
 * @since 2.0.0
 */
export const omit: {
  /**
   * Create a new object by omitting properties of an existing object.
   *
   * @example
   * ```ts
   * import * as assert from "node:assert"
   * import { pipe, Struct } from "effect"
   *
   * assert.deepStrictEqual(pipe({ a: "a", b: 1, c: true }, Struct.omit("c")), { a: "a", b: 1 })
   * assert.deepStrictEqual(Struct.omit({ a: "a", b: 1, c: true }, "c"), { a: "a", b: 1 })
   * ```
   *
   * @since 2.0.0
   */
  <Keys extends Array<PropertyKey>>(...keys: Keys): <S extends { [K in Keys[number]]?: any }>(s: S) => Simplify<Omit<S, Keys[number]>>
  /**
   * Create a new object by omitting properties of an existing object.
   *
   * @example
   * ```ts
   * import * as assert from "node:assert"
   * import { pipe, Struct } from "effect"
   *
   * assert.deepStrictEqual(pipe({ a: "a", b: 1, c: true }, Struct.omit("c")), { a: "a", b: 1 })
   * assert.deepStrictEqual(Struct.omit({ a: "a", b: 1, c: true }, "c"), { a: "a", b: 1 })
   * ```
   *
   * @since 2.0.0
   */
  <S extends object, Keys extends Array<keyof S>>(s: S, ...keys: Keys): Simplify<Omit<S, Keys[number]>>
} = dual(
  (args) => Predicate.isObject(args[0]),
  <S extends object, Keys extends Array<keyof S>>(s: S, ...keys: Keys) => {
    const out: any = { ...s }
    for (const k of keys) {
      delete out[k]
    }
    return out
  }
)

/**
 * Given a struct of `Equivalence`s returns a new `Equivalence` that compares values of a struct
 * by applying each `Equivalence` to the corresponding property of the struct.
 *
 * Alias of {@link Equivalence.struct}.
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { Struct, String, Number } from "effect"
 *
 * const PersonEquivalence = Struct.getEquivalence({
 *   name: String.Equivalence,
 *   age: Number.Equivalence
 * })
 *
 * assert.deepStrictEqual(
 *   PersonEquivalence({ name: "John", age: 25 }, { name: "John", age: 25 }),
 *   true
 * )
 * assert.deepStrictEqual(
 *   PersonEquivalence({ name: "John", age: 25 }, { name: "John", age: 40 }),
 *   false
 * )
 * ```
 *
 * @category combinators
 * @since 2.0.0
 */
export const getEquivalence: <R extends Record<string, Equivalence.Equivalence<any>>>(
  isEquivalents: R
) => Equivalence.Equivalence<
  { readonly [K in keyof R]: [R[K]] extends [Equivalence.Equivalence<infer A>] ? A : never }
> = Equivalence.struct

/**
 * This function creates and returns a new `Order` for a struct of values based on the given `Order`s
 * for each property in the struct.
 *
 * Alias of {@link order.struct}.
 *
 * @category combinators
 * @since 2.0.0
 */
export const getOrder: <R extends { readonly [x: string]: order.Order<any> }>(
  fields: R
) => order.Order<{ [K in keyof R]: [R[K]] extends [order.Order<infer A>] ? A : never }> = order.struct

type Transformed<O, T> =
  & unknown
  & {
    [K in keyof O]: K extends keyof T ? (T[K] extends (...a: any) => any ? ReturnType<T[K]> : O[K]) : O[K]
  }
type PartialTransform<O, T> = {
  [K in keyof T]: T[K] extends (a: O[K & keyof O]) => any ? T[K] : (a: O[K & keyof O]) => unknown
}
/**
 * Transforms the values of a Struct provided a transformation function for each key.
 * If no transformation function is provided for a key, it will return the original value for that key.
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { pipe, Struct } from "effect"
 *
 * assert.deepStrictEqual(
 *   pipe(
 *     { a: 'a', b: 1, c: 3 },
 *     Struct.evolve({
 *       a: (a) => a.length,
 *       b: (b) => b * 2
 *     })
 *   ),
 *   { a: 1, b: 2, c: 3 }
 * )
 * ```
 *
 * @since 2.0.0
 */
export const evolve: {
  /**
   * Transforms the values of a Struct provided a transformation function for each key.
   * If no transformation function is provided for a key, it will return the original value for that key.
   *
   * @example
   * ```ts
   * import * as assert from "node:assert"
   * import { pipe, Struct } from "effect"
   *
   * assert.deepStrictEqual(
   *   pipe(
   *     { a: 'a', b: 1, c: 3 },
   *     Struct.evolve({
   *       a: (a) => a.length,
   *       b: (b) => b * 2
   *     })
   *   ),
   *   { a: 1, b: 2, c: 3 }
   * )
   * ```
   *
   * @since 2.0.0
   */
  <O, T>(t: PartialTransform<O, T>): (obj: O) => Transformed<O, T>
  /**
   * Transforms the values of a Struct provided a transformation function for each key.
   * If no transformation function is provided for a key, it will return the original value for that key.
   *
   * @example
   * ```ts
   * import * as assert from "node:assert"
   * import { pipe, Struct } from "effect"
   *
   * assert.deepStrictEqual(
   *   pipe(
   *     { a: 'a', b: 1, c: 3 },
   *     Struct.evolve({
   *       a: (a) => a.length,
   *       b: (b) => b * 2
   *     })
   *   ),
   *   { a: 1, b: 2, c: 3 }
   * )
   * ```
   *
   * @since 2.0.0
   */
  <O, T>(obj: O, t: PartialTransform<O, T>): Transformed<O, T>
} = dual(
  2,
  <O, T>(obj: O, t: PartialTransform<O, T>): Transformed<O, T> => {
    const out = { ...obj }
    for (const k in t) {
      if (Object.prototype.hasOwnProperty.call(obj, k)) {
        // @ts-expect-error
        out[k] = t[k](obj[k])
      }
    }
    return out as any
  }
)

/**
 * Retrieves the value associated with the specified key from a struct.
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { pipe, Struct } from "effect"
 *
 * const value = pipe({ a: 1, b: 2 }, Struct.get("a"))
 *
 * assert.deepStrictEqual(value, 1)
 * ```
 *
 * @since 2.0.0
 */
export const get =
  <K extends PropertyKey>(key: K) => <S extends { [P in K]?: any }>(s: S): MatchRecord<S, S[K] | undefined, S[K]> =>
    s[key]

/**
 * Retrieves the object keys that are strings in a typed manner
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { Struct } from "effect"
 *
 * const symbol: unique symbol = Symbol()
 *
 * const value = {
 *   a: 1,
 *   b: 2,
 *   [symbol]: 3
 * }
 *
 * const keys: Array<"a" | "b"> = Struct.keys(value)
 *
 * assert.deepStrictEqual(keys, ["a", "b"])
 * ```
 *
 * @since 3.6.0
 */
export const keys = <T extends {}>(o: T): Array<(keyof T) & string> => Object.keys(o) as Array<(keyof T) & string>

/**
 * Retrieves the entries (key-value pairs) of an object, where keys are strings,
 * in a type-safe manner. Symbol keys are excluded from the result.
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { Struct } from "effect"
 *
 * const c = Symbol("c")
 * const value = { a: "foo", b: 1, [c]: true }
 *
 * const entries: Array<["a" | "b", string | number]> = Struct.entries(value)
 *
 * assert.deepStrictEqual(entries, [["a", "foo"], ["b", 1]])
 * ```
 *
 * @since 3.17.0
 */
export const entries = <const R>(obj: R): Array<[keyof R & string, R[keyof R & string]]> =>
  Object.entries(obj as any) as any

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