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/*
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 *  This file is part of CoCalc: Copyright © 2020 Sagemath, Inc.
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 *  License: MS-RSL – see LICENSE.md for details
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 */
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import { reduce } from "lodash";
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import { is_array, is_object } from "./type-checking";
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// compare the values in a map a by the values of b
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// or just by b if b is a number, using func(a, b)
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function map_comp_fn(func, fallback) {
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  return (a, b) => {
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    const c = {};
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    if (typeof b === "number") {
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      for (let k in a) {
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        let v = a[k];
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        c[k] = func(v, b);
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      }
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    } else {
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      for (let k in a) {
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        let v = a[k];
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        c[k] = func(v, b[k] ?? fallback);
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      }
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    }
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    return c;
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  };
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}
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export const map_limit = map_comp_fn(Math.min, Number.MAX_VALUE);
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export const map_min = map_limit;
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export const map_max = map_comp_fn(Math.max, Number.MIN_VALUE);
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// arithmetic sum of an array
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export function sum(arr, start = 0) {
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  if (start == null) {
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    start = 0;
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  }
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  return reduce(arr, (a, b) => a + b, start);
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}
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// returns true if the given map is undefined or empty, or all the values are falsy
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export function is_zero_map(map: undefined | null | object): boolean {
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  if (map == null) {
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    return true;
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  }
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  for (let k in map) {
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    if (map[k]) {
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      return false;
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    }
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  }
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  return true;
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}
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// Returns copy of map with no undefined/null values (recursive).
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// Doesn't modify map.  If map is an array, just returns it
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// with no change even if it has undefined values.
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export function map_without_undefined_and_null(map?: object): object | undefined | null {
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  if (map == null) {
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    return;
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  }
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  if (is_array(map)) {
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    return map;
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  }
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  const new_map = {};
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  for (let k in map) {
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    const v = map[k];
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    if (v == null) {
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      continue;
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    } else {
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      new_map[k] = is_object(v) ? map_without_undefined_and_null(v) : v;
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    }
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  }
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  return new_map;
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}
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// modify map in places deleting keys with null or undefined
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// values; NOT recursive.
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export function map_mutate_out_undefined_and_null(map: object): void {
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  for (let k in map) {
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    const v = map[k];
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    if (v == null) {
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      delete map[k];
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    }
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  }
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}
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