Method evaluateSlice

src/vimscript/expression/evaluate.ts:436–477

(sequence: Value, start: Value, end: Value)

  }

  private evaluateSlice(sequence: Value, start: Value, end: Value): Value {
    let _start = toInt(start);
    let _end = toInt(end);
    switch (sequence.type) {
      case 'string':
      case 'number':
      case 'float': {
        const _sequence = toString(sequence);
        while (_start < 0) {
          _start += _sequence.length;
        }
        while (_end < 0) {
          _end += _sequence.length;
        }
        if (_end < _start) {
          return str('');
        }
        return str(_sequence.substring(_start, _end + 1));
      }
      case 'list': {
        while (_start < 0) {
          _start += sequence.items.length;
        }
        while (_end < 0) {
          _end += sequence.items.length;
        }
        if (_end < _start) {
          return list([]);
        }
        return list(sequence.items.slice(_start, _end + 1));
      }
      case 'dictionary': {
        throw VimError.CannotUseSliceWithADictionary();
      }
      case 'funcref': {
        throw VimError.CannotIndexAFuncref();
      }
      case 'blob': {
        return blob(new Uint8Array(sequence.data).slice(_start, _end + 1));
      }
    }
  }

  private evaluateUnary(operator: UnaryOp, operand: Expression): NumberValue | FloatValue {
    return mapNumber(this.evaluate(operand), (x: number) => {