ui/node_modules/cytoscape/src/collection/iteration.js

import * as is from '../is' ;
import zIndexSort from './zsort' ;
import * as util from '../util';

let elesfn = ({
  forEach: function( fn, thisArg ){
    if( is.fn( fn ) ){
      let N = this.length;

      for( let i = 0; i < N; i++ ){
        let ele = this[ i ];
        let ret = thisArg ? fn.apply( thisArg, [ ele, i, this ] ) : fn( ele, i, this );

        if( ret === false ){ break; } // exit each early on return false
      }
    }

    return this;
  },

  toArray: function(){
    let array = [];

    for( let i = 0; i < this.length; i++ ){
      array.push( this[ i ] );
    }

    return array;
  },

  slice: function( start, end ){
    let array = [];
    let thisSize = this.length;

    if( end == null ){
      end = thisSize;
    }

    if( start == null ){
      start = 0;
    }

    if( start < 0 ){
      start = thisSize + start;
    }

    if( end < 0 ){
      end = thisSize + end;
    }

    for( let i = start; i >= 0 && i < end && i < thisSize; i++ ){
      array.push( this[ i ] );
    }

    return this.spawn( array );
  },

  size: function(){
    return this.length;
  },

  eq: function( i ){
    return this[ i ] || this.spawn();
  },

  first: function(){
    return this[0] || this.spawn();
  },

  last: function(){
    return this[ this.length - 1 ] || this.spawn();
  },

  empty: function(){
    return this.length === 0;
  },

  nonempty: function(){
    return !this.empty();
  },

  sort: function( sortFn ){
    if( !is.fn( sortFn ) ){
      return this;
    }

    let sorted = this.toArray().sort( sortFn );

    return this.spawn( sorted );
  },

  sortByZIndex: function(){
    return this.sort( zIndexSort );
  },

  zDepth: function(){
    let ele = this[0];
    if( !ele ){ return undefined; }

    // let cy = ele.cy();
    let _p = ele._private;
    let group = _p.group;

    if( group === 'nodes' ){
      let depth = _p.data.parent ? ele.parents().size() : 0;

      if( !ele.isParent() ){
        return util.MAX_INT - 1; // childless nodes always on top
      }

      return depth;
    } else {
      let src = _p.source;
      let tgt = _p.target;
      let srcDepth = src.zDepth();
      let tgtDepth = tgt.zDepth();

      return Math.max( srcDepth, tgtDepth, 0 ); // depth of deepest parent
    }
  }
});

elesfn.each = elesfn.forEach;

const defineSymbolIterator = () => {
  const typeofUndef = typeof undefined;
  const isIteratorSupported = typeof Symbol != typeofUndef && typeof Symbol.iterator != typeofUndef; // eslint-disable-line no-undef

  if (isIteratorSupported) {
    elesfn[Symbol.iterator] = function() { // eslint-disable-line no-undef
      let entry = { value: undefined, done: false };
      let i = 0;
      let length = this.length;

      return {
        next: () => {
          if ( i < length ) {
            entry.value = this[i++];
          } else {
            entry.value = undefined;
            entry.done = true;
          }

          return entry;
        },
        [Symbol.iterator]: function() { // eslint-disable-line no-undef
          return this;
        }
      };
    };
  }
};
defineSymbolIterator();

export default elesfn;