Code tidy + new methods in PrismFileLog.

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@8074 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/prism/PrismFileLog.java

@@ -26,113 +26,172 @@
 
 package prism;
 
+/**
+ * PrismLog object that writes all output to a file. 
+ */
 public class PrismFileLog extends PrismLog
 {
-	String filename;
-	long fp;
-	boolean stdout;
+	/** Filename (or "stdout") */
+	protected String filename;
+	/** Native file pointer, cast to a long */
+	protected long fp;
+	/** Are we writing to stdout? */
+	protected boolean stdout;
 	
+	/**
+	 * Pointless constructor. Don't call this.
+	 */
 	public PrismFileLog()
 	{
 		filename = "";
 		fp = 0;
 	}
 
-	public PrismFileLog(String s)
+	/**
+	 * Create a PRISM log which will write to {@code filename}, overwriting any previous contents.
+	 * @param filename Filename of log file
+	 */
+	public PrismFileLog(String filename)
 	{
-		open(s);
+		open(filename);
 	}
 
-	public PrismFileLog(String s, boolean append)
+	/**
+	 * Create a PRISM log which will write to {@code filename}, appending to an existing file if requested.
+	 * @param filename Filename of log file
+	 * @param append Append to the existing file?
+	 */
+	public PrismFileLog(String filename, boolean append)
 	{
-		open(s, append);
+		open(filename, append);
 	}
 
-	public void open(String s)
+	/**
+	 * Create a PRISM log which will write to {@code filename}, overwriting any previous contents.
+	 * Throw a PRISM exception if there is a problem opening the file for writing.
+	 * @param filename Filename of log file
+	 */
+	public static PrismFileLog create(String filename) throws PrismException
 	{
-		open (s, false);
+		return create(filename, false);
 	}
 	
-	public void open(String s, boolean append)
+	/**
+	 * Create a PRISM log which will write to {@code filename}, appending to an existing file if requested.
+	 * Throw a PRISM exception if there is a problem opening the file for writing.
+	 * @param filename Filename of log file
+	 * @param append Append to the existing file?
+	 */
+	public static PrismFileLog create(String filename, boolean append) throws PrismException
+	{
+		PrismFileLog log = new PrismFileLog(filename, append);
+		if (!log.ready()) {
+			throw new PrismException("Could not open file \"" + filename + "\" for output");
+		}
+		return log;
+	}
+	
+	public void open(String filename)
+	{
+		open (filename, false);
+	}
+	
+	public void open(String filename, boolean append)
 	{
-		filename = s;
-		if (s.equals("stdout")) {
+		this.filename = filename;
+		if (filename.equals("stdout")) {
 			fp = PrismNative.PN_GetStdout();
 			stdout = true;
 		}
 		else {
-			fp = append ? PrismNative.PN_OpenFileAppend(s) : PrismNative.PN_OpenFile(s);
+			fp = append ? PrismNative.PN_OpenFileAppend(filename) : PrismNative.PN_OpenFile(filename);
 			stdout = false;
 		}
 	}
 
+	// Methods for PrismLog
+	
+	@Override
 	public boolean ready()
 	{
 		return (fp != 0);
 	}
 
+	@Override
 	public long getFilePointer()
 	{
 		return fp;
 	}
 
+	@Override
 	public void flush()
 	{
 		PrismNative.PN_FlushFile(fp);
 	}
 
+	@Override
 	public void close()
 	{
 		if (!stdout) PrismNative.PN_CloseFile(fp);
 	}
 	
-	// Basic print methods
-	
+	@Override
 	public void print(boolean b)
 	{
 		printToLog("" + b);
 	}
 
+	@Override
 	public void print(char c)
 	{
 		printToLog("" + c);
 	}
 
+	@Override
 	public void print(double d)
 	{
 		printToLog("" + d);
 	}
 
+	@Override
 	public void print(float f)
 	{
 		printToLog("" + f);
 	}
 
+	@Override
 	public void print(int i)
 	{
 		printToLog("" + i);
 	}
 
+	@Override
 	public void print(long l)
 	{
 		printToLog("" + l);
 	}
 
+	@Override
 	public void print(Object obj)
 	{
 		printToLog("" + obj);
 	}
 
+	@Override
 	public void print(String s)
 	{
 		printToLog(s);
 	}
 
+	@Override
 	public void println()
 	{
 		printToLog("\n");
 	}
 
+	/**
+	 * Do the actual write (via native code).
+	 */
 	private void printToLog(String s)
 	{
 		PrismNative.PN_PrintToFile(fp, s);