isdirectory.java

来自「JAVA 数学程序库 提供常规的数值计算程序包」· Java 代码 · 共 56 行

package jmathlib.toolbox.io;

import jmathlib.core.tokens.*;
import jmathlib.core.tokens.numbertokens.DoubleNumberToken;
import jmathlib.core.functions.ExternalFunction;
import java.io.*;

public class isdirectory extends ExternalFunction
{
	public OperandToken evaluate(Token[] operands)
	{

        if (getNArgIn(operands) != 1)
			throwMathLibException("isdirectory: number of arguments != 1");

		if (!(operands[0] instanceof CharToken)) 
            throwMathLibException("isdirectory: argument must be a string");

        String name = ((CharToken)operands[0]).toString();

		try
		{
			File dir = new File(getWorkingDirectory(),name);

			if (dir.isDirectory())
			    return new DoubleNumberToken(1);
            else
                return new DoubleNumberToken(0);
                
		}
		catch (Exception e)
		{
            throwMathLibException("isdirectory: IO exception");
		}		    

		return null;		

	} // end eval
}

/*
@GROUP
IO
@SYNTAX
isdirectory(name)
@DOC
checks if the given name is a directory
@EXAMPLES
<programlisting>
isdirectory("bar");
</programlisting>
@SEE
cd, createnewfile, dir, exist, mkdir, rmdir, delete, isfile, ishidden, lastmodified
*/