content: package com.alibaba.qlexpress4.runtime.instruction;
  
  import com.alibaba.qlexpress4.QLOptions;
  import com.alibaba.qlexpress4.exception.ErrorReporter;
  import com.alibaba.qlexpress4.exception.QLErrorCodes;
  import com.alibaba.qlexpress4.runtime.QContext;
  import com.alibaba.qlexpress4.runtime.QResult;
  import com.alibaba.qlexpress4.runtime.Value;
  import com.alibaba.qlexpress4.runtime.data.DataValue;
  import com.alibaba.qlexpress4.runtime.util.ValueUtils;
  import com.alibaba.qlexpress4.utils.PrintlnUtils;
  
  import java.lang.reflect.Array;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.function.Consumer;
  
  /**
   * Operation: slice array or list, like a[2:4], a[4:-1], a[:4], a[5:], a[:]
   * Input: 0-2
   * Output: 1
   * <p>
   * Author: DQinYuan
   */
  public class SliceInstruction extends QLInstruction {
      
      public enum Mode {
          LEFT, RIGHT, BOTH, COPY
      }
      
      private final Mode mode;
      
      public SliceInstruction(ErrorReporter errorReporter, Mode mode) {
          super(errorReporter);
          this.mode = mode;
      }
      
      @Override
      public QResult execute(QContext qContext, QLOptions qlOptions) {
          int startInt = 0;
          int endInt = 0;
          Object indexAble = null;
          if (mode == Mode.BOTH) {
              Object end = qContext.pop().get();
              Object start = qContext.pop().get();
              indexAble = qContext.pop().get();
              startInt =
                  ValueUtils
                      .assertType(start,
                          Number.class,
                          QLErrorCodes.INVALID_INDEX.name(),
                          QLErrorCodes.INVALID_INDEX.getErrorMsg(),
                          errorReporter)
                      .intValue();
              endInt =
                  ValueUtils
                      .assertType(end,
                          Number.class,
                          QLErrorCodes.INVALID_INDEX.name(),
                          QLErrorCodes.INVALID_INDEX.getErrorMsg(),
                          errorReporter)
                      .intValue();
          }
          else if (mode == Mode.LEFT) {
              Object end = qContext.pop().get();
              indexAble = qContext.pop().get();
              endInt =
                  ValueUtils
                      .assertType(end,
                          Number.class,
                          QLErrorCodes.INVALID_INDEX.name(),
                          QLErrorCodes.INVALID_INDEX.getErrorMsg(),
                          errorReporter)
                      .intValue();
          }
          else if (mode == Mode.RIGHT) {
              Object start = qContext.pop().get();
              indexAble = qContext.pop().get();
              startInt =
                  ValueUtils
                      .assertType(start,
                          Number.class,
                          QLErrorCodes.INVALID_INDEX.name(),
                          QLErrorCodes.INVALID_INDEX.getErrorMsg(),
                          errorReporter)
                      .intValue();
              endInt = indexAbleLen(indexAble);
          }
          else if (mode == Mode.COPY) {
              indexAble = qContext.pop().get();
              endInt = indexAbleLen(indexAble);
          }
          
          if (indexAble instanceof List) {
              List<?> result = listSlice((List<?>)indexAble, startInt, endInt);
              qContext.push(new DataValue(result));
              return QResult.NEXT_INSTRUCTION;
          }
          else if (indexAble != null && indexAble.getClass().isArray()) {
              Object result = arraySlice(indexAble, startInt, endInt);
              qContext.push(new DataValue(result));
              return QResult.NEXT_INSTRUCTION;
          }
          else if (indexAble == null && qlOptions.isAvoidNullPointer()) {
              qContext.push(Value.NULL_VALUE);
              return QResult.NEXT_INSTRUCTION;
          }
          else {
              throw errorReporter.reportFormat(QLErrorCodes.NONINDEXABLE_OBJECT.name(),
                  QLErrorCodes.NONINDEXABLE_OBJECT.getErrorMsg(),
                  indexAble == null ? "null" : indexAble.getClass().getName());
          }
      }
      
      private int indexAbleLen(Object indexAble) {
          if (indexAble instanceof List) {
              return ((List<?>)indexAble).size();
          }
          else if (indexAble != null && indexAble.getClass().isArray()) {
              return Array.getLength(indexAble);
          }
          else {
              throw errorReporter.reportFormat(QLErrorCodes.NONINDEXABLE_OBJECT.name(),
                  QLErrorCodes.NONINDEXABLE_OBJECT.getErrorMsg(),
                  indexAble == null ? "null" : indexAble.getClass().getName());
          }
      }
      
      private List<?> listSlice(List<?> listObj, int originStart, int originEnd) {
          int start = Math.max(ValueUtils.javaIndex(listObj.size(), originStart), 0);
          int end = Math.min(ValueUtils.javaIndex(listObj.size(), originEnd), listObj.size());
          if (start >= end) {
              return new ArrayList<>(0);
          }
          
          return listObj.subList(start, end);
      }
      
      private Object arraySlice(Object arrObj, int originStart, int originEnd) {
          int arrLen = Array.getLength(arrObj);
          int start = Math.max(ValueUtils.javaIndex(arrLen, originStart), 0);
          int end = Math.min(ValueUtils.javaIndex(arrLen, originEnd), arrLen);
          if (start >= end) {
              return Array.newInstance(arrObj.getClass().getComponentType(), 0);
          }
          
          Object newArr = Array.newInstance(arrObj.getClass().getComponentType(), end - start);
          for (int i = start; i < end; i++) {
              Array.set(newArr, i - start, Array.get(arrObj, i));
          }
          return newArr;
      }
      
      @Override
      public int stackInput() {
          if (mode == Mode.BOTH) {
              return 2;
          }
          else if (mode == Mode.COPY) {
              return 0;
          }
          else {
              return 1;
          }
      }
      
      @Override
      public int stackOutput() {
          return 1;
      }
      
      @Override
      public void println(int index, int depth, Consumer<String> debug) {
          PrintlnUtils.printlnByCurDepth(depth, index + ": Slice", debug);
      }
  }
  