mingo/esm/operators/window/_internal.js

MongoDB query language for in-memory objects

import { groupBy } from "../../util";
import { $push } from "../accumulator/push";
const memo = /* @__PURE__ */ new WeakMap();
const cached = (xs) => memo.has(xs);
function withMemo(collection, expr, initialize, fn) {
  if (!memo.has(collection)) {
    memo.set(collection, {});
  }
  const data = memo.get(collection);
  if (!(expr.field in data)) {
    data[expr.field] = initialize();
  }
  let ok = false;
  try {
    const res = fn(data[expr.field]);
    ok = true;
    return res;
  } finally {
    if (!ok) {
      memo.delete(collection);
    } else if (expr.documentNumber === collection.length) {
      delete data[expr.field];
      if (Object.keys(data).length === 0) memo.delete(collection);
    }
  }
}
function rank(_, collection, expr, options, dense) {
  return withMemo(
    collection,
    expr,
    () => {
      const sortKey = "$" + Object.keys(expr.parentExpr.sortBy)[0];
      const values = $push(collection, sortKey, options);
      const groups = groupBy(
        values,
        ((_2, n) => values[n])
      );
      let i = 0;
      let offset = 0;
      for (const key of groups.keys()) {
        const len = groups.get(key).length;
        groups.set(key, [i++, offset]);
        offset += len;
      }
      return { values, groups };
    },
    ({ values, groups }) => {
      if (groups.size == collection.length) return expr.documentNumber;
      const current = values[expr.documentNumber - 1];
      const [i, n] = groups.get(current);
      return (dense ? i : n) + 1;
    }
  );
}
export {
  cached,
  rank,
  withMemo
};