content: package com.alibaba.qlexpress4.runtime.instruction;
  
  import com.alibaba.qlexpress4.QLOptions;
  import com.alibaba.qlexpress4.exception.ErrorReporter;
  import com.alibaba.qlexpress4.runtime.QContext;
  import com.alibaba.qlexpress4.runtime.QResult;
  import com.alibaba.qlexpress4.runtime.data.DataValue;
  import com.alibaba.qlexpress4.runtime.trace.ExpressionTrace;
  import com.alibaba.qlexpress4.utils.PrintlnUtils;
  
  import java.util.function.Consumer;
  
  /**
   * Operation: push constObj to stack
   * Input: 0
   * Output: 1
   * <p>
   * Author: DQinYuan
   */
  public class ConstInstruction extends QLInstruction {
      
      private final Object constObj;
      
      private final Integer traceKey;
      
      public ConstInstruction(ErrorReporter errorReporter, Object constObj, Integer traceKey) {
          super(errorReporter);
          this.constObj = constObj;
          this.traceKey = traceKey;
      }
      
      @Override
      public QResult execute(QContext qContext, QLOptions qlOptions) {
          qContext.push(new DataValue(constObj));
          
          // trace
          ExpressionTrace expressionTrace = qContext.getTraces().getExpressionTraceByKey(traceKey);
          if (expressionTrace != null) {
              expressionTrace.valueEvaluated(constObj);
          }
          
          return QResult.NEXT_INSTRUCTION;
      }
      
      @Override
      public int stackInput() {
          return 0;
      }
      
      @Override
      public int stackOutput() {
          return 1;
      }
      
      public Object getConstObj() {
          return constObj;
      }
      
      @Override
      public void println(int index, int depth, Consumer<String> debug) {
          PrintlnUtils.printlnByCurDepth(depth,
              index + ": LoadConst " + (constObj == null ? "null" : constObj.toString()),
              debug);
      }
  }
  