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Posted to dev@velocity.apache.org by Apache Wiki <wi...@apache.org> on 2005/03/30 22:11:24 UTC
[Jakarta-velocity Wiki] Update of "ListTool" by ShinobuKawaiYoshida
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The following page has been changed by ShinobuKawaiYoshida:
http://wiki.apache.org/jakarta-velocity/ListTool
The comment on the change is:
Separated the tool into two.
------------------------------------------------------------------------------
Replacement of ArrayTool.
+
+ Separated the tool into two.
+
+ ListTool (basic functions for manipulating lists)
+ * get/set/size support
+ * isEmpty support
+ * contains support
+ * isList/isArray
+
+ Extended ListTool (extended functions that we are not sure we need)
+ * conversion between Lists and arrays
+ * clone support
+ * length support (same as size)
{{{
/*
@@ -22, +35 @@
package org.apache.velocity.tools.generic;
import java.lang.reflect.Array;
- import java.util.ArrayList;
import java.util.List;
/**
* Tool for working with Lists and arrays in Velocity templates.
- * It provides a method to get and set specified elements,
+ * It provides a method to get and set specified elements.
- * retrieve the length, and create clones of a list or an array object.
- * Also provides a method to convert arrays into Lists and
- * Lists into arrays.
+ * 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}
+ * $primes -> new int[] {2, 3, 5, 7}
- * $list.length($primes) -> 4
+ * $list.size($primes) -> 4
- * $list.get($primes, 2) -> 5
+ * $list.get($primes, 2) -> 5
- * $list.clone($primes) -> int[] {2, 3, 5, 7}, != $primes
- * $list.set($primes, 2, 1) -> (primes[2] becomes 1)
+ * $list.set($primes, 2, 1) -> (primes[2] becomes 1)
- * $list.get($primes, 2) -> 1
+ * $list.get($primes, 2) -> 1
- * $list.get($clone, 2) -> 5
+ * $list.isEmpty($primes) -> false
+ * $list.contains($primes, 7) -> true
*
* Example toolbox.xml config (if you want to use this with VelocityView):
* <tool>
@@ -178, +192 @@
}
/**
- * Gets the length of an array/List.
- * It will return null under the following conditions:
- * <ul>
- * <li><code>array</code> is null.</li>
- * <li><code>array</code> is not an array/List.</li>
- * </ul>
- * The result will be same as the {@link #size(Object)} method.
- * @param array the array object.
- * @return the length of the array.
- * @see #size(Object)
- */
- public Integer length(Object array)
- {
- if (this.isList(array))
- {
- return this.size(array);
- }
- if (!this.isArray(array))
- {
- return null;
- }
-
- // Thanks to Eric Fixler for this refactor.
- return new Integer(Array.getLength(array));
- }
-
- /**
* Gets the size of a List/array.
* It will return null under the following conditions:
* <ul>
@@ -220, +207 @@
{
if (this.isArray(list))
{
- return this.length(list);
+ // Thanks to Eric Fixler for this refactor.
+ return new Integer(Array.getLength(list));
}
if (!this.isList(list))
{
@@ -228, +216 @@
}
return new Integer(((List) list).size());
- }
-
- /**
- * Gets the clone 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/array object.
- * @return the clone of the List/array.
- */
- public Object clone(Object list)
- {
- if (this.isList(list))
- {
- return new ArrayList(((List) list));
- }
- if (!this.isArray(list))
- {
- return null;
- }
-
- Class type = list.getClass().getComponentType();
- int length = Array.getLength(list);
- Object clone = Array.newInstance(type, length);
- System.arraycopy(list, 0, clone, 0, length);
- return clone;
}
/**
@@ -283, +243 @@
}
/**
+ * 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 = this.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 (this.isArray(list))
+ {
+ return this.arrayContains(list, element);
+ }
+ if (!this.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 = this.size(array).intValue();
+
+ for (int index = 0; index < size; ++index)
+ {
+ if (this.equals(element, this.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);
+ }
+
+ }
+ }}}
+
+ {{{
+ /*
+ * 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.lang.reflect.Method;
+ import java.util.ArrayList;
+ import java.util.List;
+
+ /**
+ * Tool for working with Lists and arrays in Velocity templates.
+ * In addition to the features ListTool provides,
+ * it provides the function to retrieve the length,
+ * and create clones of a list or an array object.
+ * Also provides a method to convert arrays into Lists and
+ * Lists into arrays.
+ *
+ * <p><pre>
+ * Example uses:
+ * $primes -> new int[] {2, 3, 5, 7}
+ * $list.length($primes) -> 4
+ * $list.get($primes, 2) -> 5
+ * $list.clone($primes) -> int[] {2, 3, 5, 7}, != $primes
+ * $list.set($primes, 2, 1) -> (primes[2] becomes 1)
+ * $list.get($primes, 2) -> 1
+ * $list.get($clone, 2) -> 5
+ *
+ * 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.ExtendedListTool</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:shinobu@ieee.org">Shinobu Kawai</a>
+ * @version $Id: $
+ */
+ public class ExtendedListTool extends ListTool
+ {
+
+ /**
+ * Default constructor.
+ */
+ public ExtendedListTool()
+ {
+ }
+
+ /**
* Converts an array object into a List.
* <ul>
* <li>
@@ -304, +406 @@
* @param array an array object.
* @return the converted java.util.List.
*/
- public List list(Object array)
+ public List toList(Object array)
{
if (this.isList(array)) {
return (List) array;
@@ -343, +445 @@
* @param list a List object.
* @return the converted array.
*/
- public Object array(Object list)
+ public Object toArray(Object list)
{
if (this.isArray(list))
{
@@ -358, +460 @@
return asList.toArray(new Object[asList.size()]);
}
+ /**
+ * Gets the length of an array/List.
+ * It will return null under the following conditions:
+ * <ul>
+ * <li><code>array</code> is null.</li>
+ * <li><code>array</code> is not an array/List.</li>
+ * </ul>
+ * The result will be same as the {@link #size(Object)} method.
+ * @param array the array object.
+ * @return the length of the array.
+ * @see #size(Object)
+ */
+ public Integer length(Object array)
+ {
+ if (this.isList(array))
+ {
+ return this.size(array);
+ }
+ if (!this.isArray(array))
+ {
+ return null;
+ }
+
+ // Thanks to Eric Fixler for this refactor.
+ return new Integer(Array.getLength(array));
+ }
+
+ /**
+ * Gets the clone 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/array object.
+ * @return the clone of the List/array.
+ */
+ public Object clone(Object list)
+ {
+ if (this.isArray(list))
+ {
+ Class type = list.getClass().getComponentType();
+ int length = Array.getLength(list);
+ Object clone = Array.newInstance(type, length);
+ System.arraycopy(list, 0, clone, 0, length);
+ return clone;
+ }
+ if (!this.isList(list))
+ {
+ return null;
+ }
+
+ // first, try the clone() method.
+ Class clazz = list.getClass();
+ try
+ {
+ Method cloneMethod = clazz.getMethod("clone", new Class[0]);
+ return cloneMethod.invoke(list, null);
+ }
+ catch (Exception ignoreAndTryTheNextStep)
+ {
+ }
+
+ // try to copy to a new instance.
+ try
+ {
+ List clone = (List) clazz.newInstance();
+ clone.addAll(((List) list));
+ return clone;
+ }
+ catch (Exception ignoreAndTryTheNextStep)
+ {
+ }
+
+ // last resort.
+ return new ArrayList(((List) list));
+ }
+
}
}}}