Created a utility class that allows an action to be taken only after a set

of conditions have been met. If anyone has a better suggestion for a name, I'm all ears. git-svn-id: https://samskivert.googlecode.com/svn/trunk@1712 6335cc39-0255-0410-8fd6-9bcaacd3b74c
2005-09-08 18:28:01 +00:00
parent dd02edc8e8
commit 65c34abe89
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+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2001-2004 Michael Bayne
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.util;
+
+import java.util.Arrays;
+
+/**
+ * Provides support for delaying an action until some set of conditions
+ * have been satisfied. When those conditions are satisfied, the {@link
+ * Runnable} associated with the multex is executed. This class is not
+ * intended for use by multiple threads, and runs the action during the
+ * final call to {@link #satisfied}.
+ *
+ * <p> When the final condition has been {@link #satisfied}, the action is
+ * fired and the multex is reset.
+ */
+public class Multex
+{
+    /** A convenient constant for the first action. */
+    public static final int CONDITION_ONE = 0;
+
+    /** A convenient constant for the second action. */
+    public static final int CONDITION_TWO = 1;
+
+    /** A convenient constant for the third action. */
+    public static final int CONDITION_THREE = 2;
+
+    /** A convenient constant for the fourth action. */
+    public static final int CONDITION_FOUR = 3;
+
+    /** A convenient constant for the fifth action. */
+    public static final int CONDITION_FIVE = 4;
+
+    public Multex (Runnable action, int conditions)
+    {
+        _action = action;
+        _conditions = new boolean[conditions];
+    }
+
+    /**
+     * Indicates that the specified condition has been satisfied. If this
+     * condition is the last remaining condition, the multex will be reset
+     * and the action will be fired (in that order) before this method
+     * call returns.
+     */
+    public void satisfied (int condition)
+    {
+        // sanity check
+        if (condition < 0 || condition >= _conditions.length) {
+            throw new IllegalArgumentException(
+                "Invalid condition supplied: " + condition + ". " +
+                "Maximum is " + (_conditions.length-1) + ".");
+        }
+
+        // note that this condition was satisfied
+        _conditions[condition] = true;
+
+        // check to see if unsatisfied conditions remain
+        for (int ii = 0; ii < _conditions.length; ii++) {
+            if (!_conditions[ii]) {
+                return;
+            }
+        }
+
+        // reset ourselves and fire the action
+        reset();
+        _action.run();
+    }
+
+    /**
+     * Resets this multex, setting all conditions to unsatisfied.
+     */
+    public void reset ()
+    {
+        Arrays.fill(_conditions, false);
+    }
+
+    protected Runnable _action;
+    protected boolean[] _conditions;
+}