import { Mapping } from "./interfaces" ; /**
 * Creates a  Mapping instance that keeps an array of result objects synchronized with an array of source objects.
 * See  http .
 *
 *  param param param getSourceKey param createResult param updateResult export let createMapping = < Source , Target > ( getSourceKey , createResult , updateResult ) : Mapping < Source , Target > => { let keys = [ ] as unknown [ ] ; let results = [ ] as Target [ ] ; return { results : results , map : ( newSources ) => { let newKeys = newSources . map ( getSourceKey ) ; let oldTargets = results . slice ( ) ; let oldIndex = 0 ; for ( let i = 0 ; i < newSources . length ; i ++ ) { let source = newSources [ i ] ; let sourceKey = newKeys [ i ] ; if ( sourceKey === keys [ oldIndex ] ) { results [ i ] = oldTargets [ oldIndex ] ; updateResult ( source , oldTargets [ oldIndex ] , i ) ; oldIndex ++ ; } else { let found = false ; for ( let j = 1 ; j < keys . length + 1 ; j ++ ) { let searchIndex = ( oldIndex + j ) % keys . length ; if ( keys [ searchIndex ] === sourceKey ) { results [ i ] = oldTargets [ searchIndex ] ; updateResult ( newSources [ i ] , oldTargets [ searchIndex ] , i ) ; oldIndex = searchIndex + 1 ; found = true ; break ; } } if ( ! found ) { results [ i ] = createResult ( source , i ) ; } } } results . length = newSources . length ; keys = newKeys ; } , } ; } ;