// https://d3js.org/d3-collection/ v1.0.7 Copyright 2018 Mike Bostock
(function (global, factory) {
typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
typeof define === 'function' && define.amd ? define(['exports'], factory) :
(factory((global.d3 = global.d3 || {})));
}(this, (function (exports) { 'use strict';

var prefix = "$";

function Map() {}

Map.prototype = map.prototype = {
  constructor: Map,
  has: function(key) {
    return (prefix + key) in this;
  },
  get: function(key) {
    return this[prefix + key];
  },
  set: function(key, value) {
    this[prefix + key] = value;
    return this;
  },
  remove: function(key) {
    var property = prefix + key;
    return property in this && delete this[property];
  },
  clear: function() {
    for (var property in this) if (property[0] === prefix) delete this[property];
  },
  keys: function() {
    var keys = [];
    for (var property in this) if (property[0] === prefix) keys.push(property.slice(1));
    return keys;
  },
  values: function() {
    var values = [];
    for (var property in this) if (property[0] === prefix) values.push(this[property]);
    return values;
  },
  entries: function() {
    var entries = [];
    for (var property in this) if (property[0] === prefix) entries.push({key: property.slice(1), value: this[property]});
    return entries;
  },
  size: function() {
    var size = 0;
    for (var property in this) if (property[0] === prefix) ++size;
    return size;
  },
  empty: function() {
    for (var property in this) if (property[0] === prefix) return false;
    return true;
  },
  each: function(f) {
    for (var property in this) if (property[0] === prefix) f(this[property], property.slice(1), this);
  }
};

function map(object, f) {
  var map = new Map;

  // Copy constructor.
  if (object instanceof Map) object.each(function(value, key) { map.set(key, value); });

  // Index array by numeric index or specified key function.
  else if (Array.isArray(object)) {
    var i = -1,
        n = object.length,
        o;

    if (f == null) while (++i < n) map.set(i, object[i]);
    else while (++i < n) map.set(f(o = object[i], i, object), o);
  }

  // Convert object to map.
  else if (object) for (var key in object) map.set(key, object[key]);

  return map;
}

function nest() {
  var keys = [],
      sortKeys = [],
      sortValues,
      rollup,
      nest;

  function apply(array, depth, createResult, setResult) {
    if (depth >= keys.length) {
      if (sortValues != null) array.sort(sortValues);
      return rollup != null ? rollup(array) : array;
    }

    var i = -1,
        n = array.length,
        key = keys[depth++],
        keyValue,
        value,
        valuesByKey = map(),
        values,
        result = createResult();

    while (++i < n) {
      if (values = valuesByKey.get(keyValue = key(value = array[i]) + "")) {
        values.push(value);
      } else {
        valuesByKey.set(keyValue, [value]);
      }
    }

    valuesByKey.each(function(values, key) {
      setResult(result, key, apply(values, depth, createResult, setResult));
    });

    return result;
  }

  function entries(map$$1, depth) {
    if (++depth > keys.length) return map$$1;
    var array, sortKey = sortKeys[depth - 1];
    if (rollup != null && depth >= keys.length) array = map$$1.entries();
    else array = [], map$$1.each(function(v, k) { array.push({key: k, values: entries(v, depth)}); });
    return sortKey != null ? array.sort(function(a, b) { return sortKey(a.key, b.key); }) : array;
  }

  return nest = {
    object: function(array) { return apply(array, 0, createObject, setObject); },
    map: function(array) { return apply(array, 0, createMap, setMap); },
    entries: function(array) { return entries(apply(array, 0, createMap, setMap), 0); },
    key: function(d) { keys.push(d); return nest; },
    sortKeys: function(order) { sortKeys[keys.length - 1] = order; return nest; },
    sortValues: function(order) { sortValues = order; return nest; },
    rollup: function(f) { rollup = f; return nest; }
  };
}

function createObject() {
  return {};
}

function setObject(object, key, value) {
  object[key] = value;
}

function createMap() {
  return map();
}

function setMap(map$$1, key, value) {
  map$$1.set(key, value);
}

function Set() {}

var proto = map.prototype;

Set.prototype = set.prototype = {
  constructor: Set,
  has: proto.has,
  add: function(value) {
    value += "";
    this[prefix + value] = value;
    return this;
  },
  remove: proto.remove,
  clear: proto.clear,
  values: proto.keys,
  size: proto.size,
  empty: proto.empty,
  each: proto.each
};

function set(object, f) {
  var set = new Set;

  // Copy constructor.
  if (object instanceof Set) object.each(function(value) { set.add(value); });

  // Otherwise, assume it’s an array.
  else if (object) {
    var i = -1, n = object.length;
    if (f == null) while (++i < n) set.add(object[i]);
    else while (++i < n) set.add(f(object[i], i, object));
  }

  return set;
}

function keys(map) {
  var keys = [];
  for (var key in map) keys.push(key);
  return keys;
}

function values(map) {
  var values = [];
  for (var key in map) values.push(map[key]);
  return values;
}

function entries(map) {
  var entries = [];
  for (var key in map) entries.push({key: key, value: map[key]});
  return entries;
}

exports.nest = nest;
exports.set = set;
exports.map = map;
exports.keys = keys;
exports.values = values;
exports.entries = entries;

Object.defineProperty(exports, '__esModule', { value: true });

})));