@alcorexchange/alcor-swap-sdk/build/esm/utils/getBestSwapRoute.js

​​ **npm** ``` npm i @alcorexchange/alcor-swap-sdk ``` **yarn** ``` yarn add @alcorexchange/alcor-swap-sdk ``` ## Usage ### Import:

import Queue from 'mnemonist/queue';
import { TradeType } from '../internalConstants';
export function getBestSwapRoute(routeType, percentToQuotes, percents, swapRouteConfig = {
  minSplits: 1,
  maxSplits: 8
}) {
  const {
    minSplits,
    maxSplits,
    branchFactor = 1,
    candidateLimit = 0
  } = swapRouteConfig;
  const branchWidth = Math.max(1, branchFactor);
  const quoteCompFn = routeType === TradeType.EXACT_INPUT ? (a, b) => a.greaterThan(b) : (a, b) => a.lessThan(b);
  const quoteOf = routeType === TradeType.EXACT_INPUT ? q => q.outputAmount : q => q.inputAmount;

  // Build pool bit ids without intermediate arrays.
  const poolToBit = new Map();
  let bitCounter = BigInt(0);
  for (const quotes of Object.values(percentToQuotes)) {
    for (const quote of quotes) {
      for (const pool of quote.route.pools) {
        if (!poolToBit.has(pool.id)) {
          poolToBit.set(pool.id, BigInt(1) << bitCounter);
          bitCounter += BigInt(1);
        }
      }
    }
  }
  const routeToMask = new Map();
  for (const quotes of Object.values(percentToQuotes)) {
    for (const quote of quotes) {
      let mask = BigInt(0);
      for (const pool of quote.route.pools) {
        mask |= poolToBit.get(pool.id);
      }
      routeToMask.set(quote, mask);
    }
  }
  const percentToSortedQuotes = {};
  for (const percent in percentToQuotes) {
    const sorted = percentToQuotes[percent].sort((a, b) => {
      const qa = quoteOf(a);
      const qb = quoteOf(b);
      return quoteCompFn(qa, qb) ? -1 : 1;
    });
    percentToSortedQuotes[percent] = candidateLimit > 0 && sorted.length > candidateLimit ? sorted.slice(0, candidateLimit) : sorted;
  }
  let bestQuote;
  let bestSwap;
  if ((!percentToSortedQuotes[100] || percentToSortedQuotes[100].length === 0) && minSplits <= 1) {
    console.log('Did not find a valid route without any splits. Continuing search anyway.');
  } else if (minSplits <= 1 && percentToSortedQuotes[100] && percentToSortedQuotes[100][0]) {
    bestSwap = [percentToSortedQuotes[100][0]];
    bestQuote = quoteOf(percentToSortedQuotes[100][0]);
  }
  const queue = new Queue();
  if (percents.length === 0) return null;
  for (let i = percents.length - 1; i >= 0; i--) {
    const percent = percents[i];
    const candidates = percentToSortedQuotes[percent];
    if (!candidates || candidates.length === 0) continue;
    const seeds = candidates.slice(0, branchWidth);
    for (const seed of seeds) {
      queue.enqueue({
        curRoutes: [seed],
        percentIndex: i,
        remainingPercent: 100 - percent,
        usedMask: routeToMask.get(seed),
        quoteSoFar: quoteOf(seed)
      });
    }
  }
  let splits = 1;
  while (queue.size > 0) {
    let layer = queue.size;
    splits++;
    if (splits >= 3 && bestSwap && bestSwap.length < splits - 1) {
      break;
    }
    if (splits > maxSplits) {
      break;
    }
    while (layer > 0) {
      layer--;
      const {
        remainingPercent,
        curRoutes,
        percentIndex,
        usedMask,
        quoteSoFar
      } = queue.dequeue();
      for (let i = percentIndex; i >= 0; i--) {
        const percent = percents[i];
        if (percent > remainingPercent) continue;
        const candidates = percentToSortedQuotes[percent];
        if (!candidates || candidates.length === 0) continue;
        const routeCandidates = findRoutesNotUsingUsedPools(usedMask, candidates, routeToMask, branchWidth);
        if (routeCandidates.length === 0) continue;
        for (const candidate of routeCandidates) {
          const remainingPercentNew = remainingPercent - percent;
          const usedMaskNew = usedMask | routeToMask.get(candidate);
          const quoteNew = quoteSoFar.add(quoteOf(candidate));
          if (remainingPercentNew === 0 && splits >= minSplits) {
            const curRoutesNew = curRoutes.slice();
            curRoutesNew.push(candidate);
            if (!bestQuote || quoteCompFn(quoteNew, bestQuote)) {
              bestQuote = quoteNew;
              bestSwap = curRoutesNew;
            }
          } else {
            const curRoutesNew = curRoutes.slice();
            curRoutesNew.push(candidate);
            queue.enqueue({
              curRoutes: curRoutesNew,
              remainingPercent: remainingPercentNew,
              percentIndex: i,
              usedMask: usedMaskNew,
              quoteSoFar: quoteNew
            });
          }
        }
      }
    }
  }
  if (!bestSwap) {
    console.log('Could not find a valid swap');
    return null;
  }
  return bestSwap;
}
const findRoutesNotUsingUsedPools = (usedMask, candidateRoutes, routeToMask, limit) => {
  const result = [];
  for (const candidate of candidateRoutes) {
    const candidateMask = routeToMask.get(candidate);
    if ((candidateMask & usedMask) === BigInt(0)) {
      result.push(candidate);
      if (result.length >= limit) return result;
    }
  }
  return result;
};