new resource collection "allbutfirst"

first part of https://bz.apache.org/bugzilla/show_bug.cgi?id=57834 -
allbutlast to follow

src/main/org/apache/tools/ant/types/defaults.properties

@@ -71,6 +71,7 @@ difference=org.apache.tools.ant.types.resources.Difference
 intersect=org.apache.tools.ant.types.resources.Intersect
 sort=org.apache.tools.ant.types.resources.Sort
 resources=org.apache.tools.ant.types.resources.Resources
+allbutfirst=org.apache.tools.ant.types.resources.AllButFirst
 first=org.apache.tools.ant.types.resources.First
 last=org.apache.tools.ant.types.resources.Last
 tarfileset=org.apache.tools.ant.types.TarFileSet

src/main/org/apache/tools/ant/types/resources/AllButFirst.java

@@ -0,0 +1,60 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ */
+package org.apache.tools.ant.types.resources;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+
+import org.apache.tools.ant.types.Resource;
+
+/**
+ * ResourceCollection that contains all resources of another
+ * collection except for the first <code>count</code> elements, a la
+ * the UNIX tail command with parameter <code>-n +count</code>.
+ * @since Ant 1.9.5
+ */
+public class AllButFirst extends SizeLimitCollection {
+
+    /**
+     * Take the first <code>count</code> elements.
+     * @return a Collection of Resources.
+     */
+    protected Collection<Resource> getCollection() {
+        int ct = getValidCount();
+        Iterator<Resource> iter = getResourceCollection().iterator();
+        List<Resource> al = new ArrayList<Resource>();
+        for (int i = 0; i < ct && iter.hasNext(); i++) {
+            // discard
+            iter.next();
+        }
+        while (iter.hasNext()) {
+            al.add(iter.next());
+        }
+        return al;
+    }
+
+    @Override
+    public synchronized int size() {
+        int sz = getResourceCollection().size();
+        int ct = getValidCount();
+        return sz > ct ? sz - ct : 0;
+    }
+
+}

src/tests/antunit/types/resources/first-last-test.xml

@@ -15,7 +15,9 @@
   See the License for the specific language governing permissions and
   limitations under the License.
 -->
-<project xmlns:au="antlib:org.apache.ant.antunit">
+<project xmlns:au="antlib:org.apache.ant.antunit" default="antunit">
+
+  <import file="../../antunit-base.xml" />
 
   <tokens id="testrc">
     <string value="1,2,3,4,5" />
@@ -154,4 +156,69 @@
     </au:expectfailure>
   </target>
 
+  <target name="testallbutfirst5">
+    <au:assertTrue>
+      <resourcecount count="0">
+        <allbutfirst count="5"><resources refid="testrc" /></allbutfirst>
+      </resourcecount>
+    </au:assertTrue>
+  </target>
+
+  <target name="testallbutfirst4">
+    <au:assertTrue>
+      <resourcecount count="0">
+        <difference>
+          <allbutfirst count="4"><resources refid="testrc" /></allbutfirst>
+          <string value="5" />
+        </difference>
+      </resourcecount>
+    </au:assertTrue>
+  </target>
+
+  <target name="testallbutfirst3">
+    <au:assertTrue>
+      <resourcecount count="0">
+        <difference>
+          <allbutfirst count="3"><resources refid="testrc" /></allbutfirst>
+          <resources>
+            <string value="4" />
+            <string value="5" />
+          </resources>
+        </difference>
+      </resourcecount>
+    </au:assertTrue>
+  </target>
+
+  <target name="testallbutfirst">
+    <au:assertTrue>
+      <resourcecount count="0">
+        <difference>
+          <allbutfirst><resources refid="testrc" /></allbutfirst>
+          <resources>
+            <string value="2" />
+            <string value="3" />
+            <string value="4" />
+            <string value="5" />
+          </resources>
+        </difference>
+      </resourcecount>
+    </au:assertTrue>
+  </target>
+
+  <target name="testallbutfirst6">
+    <au:assertTrue>
+      <resourcecount count="0">
+        <allbutfirst count="6"><resources refid="testrc" /></allbutfirst>
+      </resourcecount>
+    </au:assertTrue>
+  </target>
+
+  <target name="testallbutfirst-1">
+    <au:expectfailure expectedmessage="size-limited collection count should be set to an int &gt;= 0">
+      <resourcecount>
+        <allbutfirst count="-1"><resources refid="testrc" /></allbutfirst>
+      </resourcecount>
+    </au:expectfailure>
+  </target>
+
 </project>