this.onChange = function()

in public/webpackShims/ace/ext-language_tools.js [733:781]
45 lines of code
16 McCabe index (conditional complexity)

    this.onChange = function(e) {
        var changeRange = e.data.range;
        var isRemove = e.data.action[0] == "r";
        var start = changeRange.start;
        var end = changeRange.end;
        var startRow = start.row;
        var endRow = end.row;
        var lineDif = endRow - startRow;
        var colDiff = end.column - start.column;

        if (isRemove) {
            lineDif = -lineDif;
            colDiff = -colDiff;
        }
        if (!this.$inChange && isRemove) {
            var ts = this.selectedTabstop;
            var changedOutside = !ts.some(function(r) {
                return comparePoints(r.start, start) <= 0 && comparePoints(r.end, end) >= 0;
            });
            if (changedOutside)
                return this.detach();
        }
        var ranges = this.ranges;
        for (var i = 0; i < ranges.length; i++) {
            var r = ranges[i];
            if (r.end.row < start.row)
                continue;

            if (comparePoints(start, r.start) < 0 && comparePoints(end, r.end) > 0) {
                this.removeRange(r);
                i--;
                continue;
            }

            if (r.start.row == startRow && r.start.column > start.column)
                r.start.column += colDiff;
            if (r.end.row == startRow && r.end.column >= start.column)
                r.end.column += colDiff;
            if (r.start.row >= startRow)
                r.start.row += lineDif;
            if (r.end.row >= startRow)
                r.end.row += lineDif;

            if (comparePoints(r.start, r.end) > 0)
                this.removeRange(r);
        }
        if (!ranges.length)
            this.detach();
    };