function taskGraphRunner/*::<Item, Result>*/(opts /*: Opts<Item, Result> */) /*: Promise<Results<Item, Result>> */ {
  let graph = opts.graph;
  let task = opts.task;
  let force = opts.force || false;

  let safe = true;
  let queue = new Set(graph.keys());
  let running = new Set();

  function getNextChunk() {
    let chunk = [];
    let current = new Map();

    if (!queue.size) {
      return chunk;
    }

    for (let key of queue) {
      let deps = graph.get(key) || [];
      let curr = deps.filter(dep => queue.has(dep));

      current.set(key, curr);

      if (!curr.length) {
        chunk.push(key);
      }
    }

    if (chunk.length === 0) {
      if (!force) {
        throw new Error('Cycle detected in graph');
      }

      let items = Array.from(queue);
      let sorted = items.sort((a, b) => {
        let aCurr = current.get(a) || [];
        let bCurr = current.get(b) || [];
        let deps = aCurr.length - bCurr.length;
        if (deps !== 0) return deps;

        let aChildren = items.filter(item => arrayIncludes(current.get(item) || [], a));
        let bChildren = items.filter(item => arrayIncludes(current.get(item) || [], b));
        return bChildren.length - aChildren.length;
      });

      let first = sorted[0];

      chunk.push(first);
      safe = false;
    }

    chunk = chunk.filter(key => {
      let deps = graph.get(key) || [];
      return !deps.find(dep => running.has(dep));
    });

    for (let key of chunk) {
      queue.delete(key);
    }

    return chunk;
  }

  let values = new Map();

  function next() {
    let chunk = getNextChunk();
    let promises /*: Array<Promise<mixed>> */ = [];

    for (let key of chunk) {
      running.add(key);
      promises.push(Promise.resolve(task(key)).then(result => {
        running.delete(key);
        values.set(key, result);

        if (queue.size) {
          return next();
        }
      }));
    }

    return Promise.all(promises);
  }

  return new Promise((resolve, reject) => {
    return next().then(resolve, reject);
  }).then(() => {
    return { safe, values };
  });
}
function taskGraphRunner(opts )  {
  let graph = opts.graph;
  let task = opts.task;
  let force = opts.force || false;

  let safe = true;
  let queue = new Set(graph.keys());
  let running = new Set();

  function getNextChunk() {
    let chunk = [];
    let current = new Map();

    if (!queue.size) {
      return chunk;
    }

    for (let key of queue) {
      let deps = graph.get(key) || [];
      let curr = deps.filter(dep => queue.has(dep));

      current.set(key, curr);

      if (!curr.length) {
        chunk.push(key);
      }
    }

    if (chunk.length === 0) {
      if (!force) {
        throw new Error('Cycle detected in graph');
      }

      let items = Array.from(queue);
      let sorted = items.sort((a, b) => {
        let aCurr = current.get(a) || [];
        let bCurr = current.get(b) || [];
        let deps = aCurr.length - bCurr.length;
        if (deps !== 0) return deps;

        let aChildren = items.filter(item => arrayIncludes(current.get(item) || [], a));
        let bChildren = items.filter(item => arrayIncludes(current.get(item) || [], b));
        return bChildren.length - aChildren.length;
      });

      let first = sorted[0];

      chunk.push(first);
      safe = false;
    }

    chunk = chunk.filter(key => {
      let deps = graph.get(key) || [];
      return !deps.find(dep => running.has(dep));
    });

    for (let key of chunk) {
      queue.delete(key);
    }

    return chunk;
  }

  let values = new Map();

  function next() {
    let chunk = getNextChunk();
    let promises  = [];

    for (let key of chunk) {
      running.add(key);
      promises.push(Promise.resolve(task(key)).then(result => {
        running.delete(key);
        values.set(key, result);

        if (queue.size) {
          return next();
        }
      }));
    }

    return Promise.all(promises);
  }

  return new Promise((resolve, reject) => {
    return next().then(resolve, reject);
  }).then(() => {
    return { safe, values };
  });
}
function taskGraphRunner /*::<Item, Result>*/ ( opts /*: Opts<Item, Result> */ ) /*: Promise<Results<Item, Result>> */ { let graph = opts . graph ; let task = opts . task ; let force = opts . force || false ; let safe = true ; let queue = new Set ( graph . keys ( ) ) ; let running = new Set ( ) ; function getNextChunk ( ) { let chunk = [ ] ; let current = new Map ( ) ; if ( ! queue . size ) { return chunk ; } for ( let key of queue ) { let deps = graph . get ( key ) || [ ] ; let curr = deps . filter ( dep => queue . has ( dep ) ) ; current . set ( key , curr ) ; if ( ! curr . length ) { chunk . push ( key ) ; } } if ( chunk . length === 0 ) { if ( ! force ) { throw new Error ( 'Cycle detected in graph' ) ; } let items = Array . from ( queue ) ; let sorted = items . sort ( ( a , b ) => { let aCurr = current . get ( a ) || [ ] ; let bCurr = current . get ( b ) || [ ] ; let deps = aCurr . length - bCurr . length ; if ( deps !== 0 ) return deps ; let aChildren = items . filter ( item => arrayIncludes ( current . get ( item ) || [ ] , a ) ) ; let bChildren = items . filter ( item => arrayIncludes ( current . get ( item ) || [ ] , b ) ) ; return bChildren . length - aChildren . length ; } ) ; let first = sorted [ 0 ] ; chunk . push ( first ) ; safe = false ; } chunk = chunk . filter ( key => { let deps = graph . get ( key ) || [ ] ; return ! deps . find ( dep => running . has ( dep ) ) ; } ) ; for ( let key of chunk ) { queue . delete ( key ) ; } return chunk ; } let values = new Map ( ) ; function next ( ) { let chunk = getNextChunk ( ) ; let promises /*: Array<Promise<mixed>> */ = [ ] ; for ( let key of chunk ) { running . add ( key ) ; promises . push ( Promise . resolve ( task ( key ) ) . then ( result => { running . delete ( key ) ; values . set ( key , result ) ; if ( queue . size ) { return next ( ) ; } } ) ) ; } return Promise . all ( promises ) ; } return new Promise ( ( resolve , reject ) => { return next ( ) . then ( resolve , reject ) ; } ) . then ( ( ) => { return { safe , values } ; } ) ; }
/*::
type Opts<Item, Result> = {
graph: Map<Item, Array<Item>>,
task: (item: Item) => Result,
force?: boolean,
};

type Results<Item, Result> = {
safe: boolean,
values: Map<Item, Result>,
};
/ * :: type Opts<Item Result > = { graph : Map<Item Array<Item >> task : ( item : Item ) = > Result force? : boolean } ;