Author: nbubna
Date: Thu Aug 18 20:58:02 2005
New Revision: 233423
URL: http://svn.apache.org/viewcvs?rev=233423&view=rev
Log:
Initial revision of contribution from Shinobu Kawai ([EMAIL PROTECTED])
Added:
jakarta/velocity/tools/trunk/src/java/org/apache/velocity/tools/generic/ListTool.java
Added:
jakarta/velocity/tools/trunk/src/java/org/apache/velocity/tools/generic/ListTool.java
URL:
http://svn.apache.org/viewcvs/jakarta/velocity/tools/trunk/src/java/org/apache/velocity/tools/generic/ListTool.java?rev=233423&view=auto
==============================================================================
---
jakarta/velocity/tools/trunk/src/java/org/apache/velocity/tools/generic/ListTool.java
(added)
+++
jakarta/velocity/tools/trunk/src/java/org/apache/velocity/tools/generic/ListTool.java
Thu Aug 18 20:58:02 2005
@@ -0,0 +1,297 @@
+/*
+ * Copyright 2003-2005 The Apache Software Foundation.
+ *
+ * Licensed 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.velocity.tools.generic;
+
+import java.lang.reflect.Array;
+import java.util.List;
+
+/**
+ * Tool for working with Lists and arrays in Velocity templates.
+ * It provides a method to get and set specified elements.
+ * Also provides methods to perform the following actions to Lists and arrays:
+ * <ul>
+ * <li>Check if it is empty.</li>
+ * <li>Check if it contains a certain element.</li>
+ * </ul>
+ *
+ * <p><pre>
+ * Example uses:
+ * $primes -> new int[] {2, 3, 5, 7}
+ * $list.size($primes) -> 4
+ * $list.get($primes, 2) -> 5
+ * $list.set($primes, 2, 1) -> (primes[2] becomes 1)
+ * $list.get($primes, 2) -> 1
+ * $list.isEmpty($primes) -> false
+ * $list.contains($primes, 7) -> true
+ *
+ * Example toolbox.xml config (if you want to use this with VelocityView):
+ * <tool>
+ * <key>list</key>
+ * <scope>application</scope>
+ * <class>org.apache.velocity.tools.generic.ListTool</class>
+ * </tool>
+ * </pre></p>
+ *
+ * <p>This tool is entirely threadsafe, and has no instance members.
+ * It may be used in any scope (request, session, or application).
+ * </p>
+ *
+ * @author <a href="mailto:[EMAIL PROTECTED]">Shinobu Kawai</a>
+ * @version $Id: $
+ */
+public class ListTool
+{
+
+ /**
+ * Default constructor.
+ */
+ public ListTool()
+ {
+ }
+
+ /**
+ * Gets the specified element of a List/array.
+ * It will return null under the following conditions:
+ * <ul>
+ * <li><code>list</code> is null.</li>
+ * <li><code>list</code> is not a List/array.</li>
+ * <li><code>list</code> doesn't have an <code>index</code>th value.</li>
+ * </ul>
+ * @param list the List/array object.
+ * @param index the index of the List/array to get.
+ * @return the specified element of the List/array.
+ */
+ public Object get(Object list, int index)
+ {
+ if (isArray(list))
+ {
+ return getFromArray(list, index);
+ }
+ if (!isList(list))
+ {
+ return null;
+ }
+
+ try
+ {
+ return ((List) list).get(index);
+ }
+ catch (IndexOutOfBoundsException e)
+ {
+ // The index was wrong.
+ return null;
+ }
+ }
+
+ /**
+ * Gets the specified element of an array.
+ * @param array the array object.
+ * @param index the index of the array to get.
+ * @return the specified element of the array.
+ */
+ private Object getFromArray(Object array, int index)
+ {
+ try
+ {
+ return Array.get(array, index);
+ }
+ catch (IndexOutOfBoundsException e)
+ {
+ // The index was wrong.
+ return null;
+ }
+ }
+
+ /**
+ * Sets the specified element of a List/array.
+ * It will return null under the following conditions:
+ * <ul>
+ * <li><code>list</code> is null.</li>
+ * <li><code>list</code> is not a List/array.</li>
+ * <li><code>list</code> doesn't have an <code>index</code>th value.</li>
+ * </ul>
+ * @param list the List/array object.
+ * @param index the index of the List/array to set.
+ * @param value the element to set.
+ * @return blank if set, null if not set.
+ */
+ public Object set(Object list, int index, Object value)
+ {
+ if (isArray(list))
+ {
+ return setToArray(list, index, value);
+ }
+ if (!isList(list))
+ {
+ return null;
+ }
+
+ try
+ {
+ ((List) list).set(index, value);
+ return "";
+ }
+ catch (IndexOutOfBoundsException e)
+ {
+ // The index was wrong.
+ return null;
+ }
+ }
+
+ /**
+ * Sets the specified element of an array.
+ * @param array the array object.
+ * @param index the index of the array to set.
+ * @param value the element to set.
+ * @return blank if set, null if not set.
+ */
+ private Object setToArray(Object array, int index, Object value)
+ {
+ try
+ {
+ Array.set(array, index, value);
+ return "";
+ }
+ catch (IndexOutOfBoundsException e)
+ {
+ // The index was wrong.
+ return null;
+ }
+ }
+
+ /**
+ * Gets the size of a List/array.
+ * It will return null under the following conditions:
+ * <ul>
+ * <li><code>list</code> is null.</li>
+ * <li><code>list</code> is not a List/array.</li>
+ * </ul>
+ * @param list the List object.
+ * @return the size of the List.
+ */
+ public Integer size(Object list)
+ {
+ if (isArray(list))
+ {
+ // Thanks to Eric Fixler for this refactor.
+ return new Integer(Array.getLength(list));
+ }
+ if (!isList(list))
+ {
+ return null;
+ }
+
+ return new Integer(((List) list).size());
+ }
+
+ /**
+ * Checks if an object is an array.
+ * @param object the object to check.
+ * @return <code>true</code> if the object is an array.
+ */
+ public boolean isArray(Object object)
+ {
+ if (object == null)
+ {
+ return false;
+ }
+ return object.getClass().isArray();
+ }
+
+ /**
+ * Checks if an object is a List.
+ * @param object the object to check.
+ * @return <code>true</code> if the object is a List.
+ */
+ public boolean isList(Object object)
+ {
+ return object instanceof List;
+ }
+
+ /**
+ * Checks if a List/array is empty.
+ * @param list the List/array to check.
+ * @return <code>true</code> if the List/array is empty.
+ */
+ public Boolean isEmpty(Object list)
+ {
+ Integer size = size(list);
+ if (size == null)
+ {
+ return null;
+ }
+
+ return new Boolean(size.intValue() == 0);
+ }
+
+ /**
+ * Checks if a List/array contains a certain element.
+ * @param list the List/array to check.
+ * @param element the element to check.
+ * @return <code>true</code> if the List/array contains the element.
+ */
+ public Boolean contains(Object list, Object element)
+ {
+ if (isArray(list))
+ {
+ return arrayContains(list, element);
+ }
+ if (!isList(list))
+ {
+ return null;
+ }
+
+ return new Boolean(((List) list).contains(element));
+ }
+
+ /**
+ * Checks if an array contains a certain element.
+ * @param array the array to check.
+ * @param element the element to check.
+ * @return <code>true</code> if the array contains the element.
+ */
+ private Boolean arrayContains(Object array, Object element)
+ {
+ int size = size(array).intValue();
+
+ for (int index = 0; index < size; ++index)
+ {
+ if (equals(element, getFromArray(array, index)))
+ {
+ return Boolean.TRUE;
+ }
+ }
+ return Boolean.FALSE;
+ }
+
+ /**
+ * Check if two objects are equal.
+ * @param what an object
+ * @param with another object.
+ * @return <code>true</code> if the two objects are equal.
+ */
+ private boolean equals(Object what, Object with)
+ {
+ if (what == null)
+ {
+ return with == null;
+ }
+
+ return what.equals(with);
+ }
+
+}
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