Replace the CommaSeparatedString transformer with an escaping

TabSeparatedString transformer. Maybe I should just use StringUtil methods...

src/java/com/samskivert/depot/Transformers.java

@@ -37,14 +37,26 @@ import com.samskivert.depot.annotation.Column;
 public class Transformers
 {
     /**
-     * Combines the contents of a String[] column into a single string, separated by commas.
+     * Combines the contents of a String[] column into a single string, separated by tabs. Any tabs
+     * in the strings will be escaped.
      */
-    public static class CommaSeparatedString implements Transformer<String[], String> {
-        public String toPersistent (String[] value) {
-            return Joiner.on(",").join(value);
+    public static class TabSeparatedString implements Transformer<String[], String> {
+        public String toPersistent (String[] values) {
+            StringBuffer buf = new StringBuffer();
+            for (String value : values) {
+                if (buf.length() > 0) {
+                    buf.append("\t");
+                }
+                buf.append(value.replace("\t", "\\\t"));
+            }
+            return buf.toString();
         }
         public String[] fromPersistent (Class<?> ftype, String value) {
-            return value.split(",");
+            String[] values = value.replace("\\\t", "%%ESCTAB%%").split("\t");
+            for (int ii = 0; ii < values.length; ii++) {
+                values[ii] = values[ii].replace("%%ESCTAB%%", "\t");
+            }
+            return values;
         }
     }
 }

src/java/com/samskivert/depot/tests/TransformTest.java

@@ -127,7 +127,7 @@ public class TransformTest extends TestBase
 
         @Id public int recordId;
 
-        @Transform(Transformers.CommaSeparatedString.class)
+        @Transform(Transformers.TabSeparatedString.class)
         public String[] strings;
 
         public CustomType custom;
@@ -151,7 +151,7 @@ public class TransformTest extends TestBase
 
     public static class BadTransformRecord extends PersistentRecord
     {
-        @Transform(Transformers.CommaSeparatedString.class)
+        @Transform(Transformers.TabSeparatedString.class)
         public Thread thread;
 
         public InvalidCustomType invalid;

src/java/com/samskivert/depot/tests/TransformersTest.java

@@ -0,0 +1,39 @@
+//
+// $Id$
+//
+// Depot library - a Java relational persistence library
+// Copyright (C) 2006-2010 Michael Bayne and Pär Winzell
+//
+// 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.depot.tests;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+import com.samskivert.depot.Transformers;
+
+/**
+ * Tests the stock transformers.
+ */
+public class TransformersTest
+{
+    @Test public void testTabSeparatedString ()
+    {
+        String[] data = { "notabs", "\tpretab", "posttab\t", "in\ttab", "\t\t\tOMGtabs!\t\t" };
+        Transformers.TabSeparatedString xform = new Transformers.TabSeparatedString();
+        assertArrayEquals(data, xform.fromPersistent(null, xform.toPersistent(data)));
+    }
+}