in src/grid/agr-engine.ts [200:211]
switchSort(column: Column, multiple?: boolean) {
switch (column.columnDef.sort) {
case ColumnSortOrder.asc:
this.addSort(column, ColumnSortOrder.desc, multiple);
break;
case ColumnSortOrder.desc:
this.options.unSortColumn ? this.removeSort(column) : this.addSort(column, ColumnSortOrder.asc, multiple);
break;
default:
this.addSort(column, ColumnSortOrder.asc, multiple);
}
}