@thi.ng/associative/join.js

ES Map/Set-compatible implementations with customizable equality semantics & supporting operations

import { commonKeysObj } from "@thi.ng/object-utils/common-keys";
import { empty } from "@thi.ng/object-utils/empty";
import { invertObj } from "@thi.ng/object-utils/invert";
import { mergeObj } from "@thi.ng/object-utils/merge";
import { renameKeysObj } from "@thi.ng/object-utils/rename-keys";
import { selectKeysObj } from "@thi.ng/object-utils/select-keys";
import { first } from "./first.js";
import { indexed } from "./indexed.js";
const join = (a, b) => {
  if (a.size && b.size) {
    const ks = commonKeysObj(first(a) || {}, first(b) || {});
    let aa, bb;
    if (a.size <= b.size) {
      aa = a;
      bb = b;
    } else {
      aa = b;
      bb = a;
    }
    const idx = indexed(aa, ks);
    const res = empty(a, Set);
    for (let x of bb) {
      const found = idx.get(selectKeysObj(x, ks));
      if (found) {
        for (let f of found) {
          res.add(mergeObj({ ...f }, x));
        }
      }
    }
    return res;
  }
  return empty(a, Set);
};
const joinWith = (a, b, kmap) => {
  if (a.size && b.size) {
    let aa, bb;
    let k;
    if (a.size <= b.size) {
      aa = a;
      bb = b;
      k = invertObj(kmap);
    } else {
      aa = b;
      bb = a;
      k = kmap;
    }
    const idx = indexed(aa, Object.values(k));
    const ks = Object.keys(k);
    const res = empty(a, Set);
    for (let x of bb) {
      const found = idx.get(renameKeysObj(selectKeysObj(x, ks), k));
      if (found) {
        for (let f of found) {
          res.add(mergeObj({ ...f }, x));
        }
      }
    }
    return res;
  }
  return empty(a, Set);
};
export {
  join,
  joinWith
};