content: package com.alibaba.qlexpress4.runtime.instruction;
  
  import com.alibaba.qlexpress4.QLOptions;
  import com.alibaba.qlexpress4.exception.ErrorReporter;
  import com.alibaba.qlexpress4.runtime.*;
  import com.alibaba.qlexpress4.runtime.trace.ExpressionTrace;
  import com.alibaba.qlexpress4.utils.PrintlnUtils;
  
  import java.util.function.Consumer;
  
  /**
   * Operation: load variable from local to global scope, create when not exist
   * Input: 0
   * Output: 1 left value of local variable
   *
   * Author: DQinYuan
   */
  public class LoadInstruction extends QLInstruction {
      
      private final String name;
      
      private final Integer traceKey;
      
      public LoadInstruction(ErrorReporter errorReporter, String name, Integer traceKey) {
          super(errorReporter);
          this.name = name;
          this.traceKey = traceKey;
      }
      
      @Override
      public QResult execute(QContext qContext, QLOptions qlOptions) {
          Value symbolValue = qContext.getSymbol(name);
          qContext.push(symbolValue);
          
          // trace
          ExpressionTrace expressionTrace = qContext.getTraces().getExpressionTraceByKey(traceKey);
          if (expressionTrace != null) {
              expressionTrace.valueEvaluated(symbolValue.get());
          }
          
          return QResult.NEXT_INSTRUCTION;
      }
      
      @Override
      public int stackInput() {
          return 0;
      }
      
      @Override
      public int stackOutput() {
          return 1;
      }
      
      public String getName() {
          return name;
      }
      
      @Override
      public void println(int index, int depth, Consumer<String> debug) {
          PrintlnUtils.printlnByCurDepth(depth, index + ": Load " + name, debug);
      }
  }
  