我想提取一个Java方法的本地数据流，到目前为止，我使用这个查询来提取函数中访问、声明或赋值变量的位置：

/**
 * @name Empty block
 * @kind problem
 * @problem.severity warning
 * @id java/example/empty-block
 */

 import java
 import semmle.code.java.dataflow.DataFlow
 

 from File fl, LocalVariableDeclExpr ld, VarAccess va, Assignment asn
 where 
     fl.getBaseName() = "Calculator.java"
     and 
     ld.getEnclosingCallable().getName()= "calc"
     and va.getEnclosingCallable().getName() = "calc"
     and asn.getEnclosingCallable().getName() = "calc"
     
     
 and ld.getLocation().getFile() = fl 
 and va.getLocation().getFile() = fl 
 and asn.getLocation().getFile() = fl 
 and va.getLocation().getStartLine() = ld.getLocation().getStartLine()
 select ld, "\"" + va.getVariable().getName()+"\""  + "->" + "\"" +ld.getVariable().getName()+"\""  + "\n" + "\"" +asn.getDest()+"\""  + "->" + "\"" +asn.getSource()+"\""  + "\n"

问题是SELECT阶段花费的时间太长。我使用this存储库作为数据库。文件名为Calculator.Java，方法如下：

public double calc(double x, String input, char opt) {
        inText.setFont(inText.getFont().deriveFont(Font.PLAIN));
        double y = Double.parseDouble(input);
        switch (opt) {
            case '+':
                return x + y;
            case '-':
                return x - y;
            case '*':
                return x * y;
            case '/':
                return x / y;
            case '%':
                return x % y;
            case '^':
                return Math.pow(x, y);
            default:
                inText.setFont(inText.getFont().deriveFont(Font.PLAIN));
                return y;
        }
    }

谢谢。