| /* |
| * 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 freemarker.template; |
| |
| import java.io.Serializable; |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.List; |
| |
| import freemarker.ext.beans.BeansWrapper; |
| |
| /** |
| * A simple implementation of the {@link TemplateSequenceModel} interface, using its own underlying {@link List} for |
| * storing the list items. If you are wrapping an already existing {@link List} or {@code array}, you should certainly |
| * use {@link DefaultMapAdapter} or {@link DefaultArrayAdapter} (see comparison below). |
| * |
| * <p> |
| * This class is thread-safe if you don't call modifying methods (like {@link #add(Object)}) after you have made the |
| * object available for multiple threads (assuming you have published it safely to the other threads; see JSR-133 Java |
| * Memory Model). These methods aren't called by FreeMarker, so it's usually not a concern. |
| * |
| * <p> |
| * <b>{@link SimpleSequence} VS {@link DefaultListAdapter}/{@link DefaultArrayAdapter} - Which to use when?</b> |
| * </p> |
| * |
| * <p> |
| * For a {@link List} or {@code array} that exists regardless of FreeMarker, only you need to access it from templates, |
| * {@link DefaultMapAdapter} should be the default choice, as it can be unwrapped to the originally wrapped object |
| * (important when passing it to Java methods from the template). It also has more predictable performance (no spikes). |
| * |
| * <p> |
| * For a sequence that's made specifically to be used from templates, creating an empty {@link SimpleSequence} then |
| * filling it with {@link SimpleSequence#add(Object)} is usually the way to go, as the resulting sequence is |
| * significantly faster to read from templates than a {@link DefaultListAdapter} (though it's somewhat slower to read |
| * from a plain Java method to which it had to be passed adapted to a {@link List}). |
| * |
| * <p> |
| * It also matters if for how many times will the <em>same</em> {@link List} entry be read from the template(s) later, |
| * on average. If, on average, you read each entry for more than 4 times, {@link SimpleSequence} will be most |
| * certainly faster, but if for 2 times or less (and especially if not at all) then {@link DefaultMapAdapter} will |
| * be faster. Before choosing based on performance though, pay attention to the behavioral differences; |
| * {@link SimpleSequence} will shallow-copy the original {@link List} at construction time, so it won't reflect |
| * {@link List} content changes after the {@link SimpleSequence} construction, also {@link SimpleSequence} can't be |
| * unwrapped to the original wrapped instance. |
| * |
| * @see DefaultListAdapter |
| * @see DefaultArrayAdapter |
| * @see TemplateSequenceModel |
| */ |
| public class SimpleSequence extends WrappingTemplateModel implements TemplateSequenceModel, Serializable { |
| |
| /** |
| * The {@link List} that stored the elements of this sequence. It migth contains both {@link TemplateModel} elements |
| * and non-{@link TemplateModel} elements. |
| */ |
| protected final List list; |
| |
| private List unwrappedList; |
| |
| /** |
| * Constructs an empty simple sequence that will use the the default object |
| * wrapper set in |
| * {@link WrappingTemplateModel#setDefaultObjectWrapper(ObjectWrapper)}. |
| * |
| * @deprecated Use {@link #SimpleSequence(ObjectWrapper)} instead. |
| */ |
| @Deprecated |
| public SimpleSequence() { |
| this((ObjectWrapper) null); |
| } |
| |
| /** |
| * Constructs an empty simple sequence with preallocated capacity and using |
| * the default object wrapper set in |
| * {@link WrappingTemplateModel#setDefaultObjectWrapper(ObjectWrapper)}. |
| * |
| * @deprecated Use {@link #SimpleSequence(int, ObjectWrapper)}. |
| */ |
| @Deprecated |
| public SimpleSequence(int capacity) { |
| list = new ArrayList(capacity); |
| } |
| |
| /** |
| * Constructs a simple sequence that will contain the elements |
| * from the specified {@link Collection} and will use the the default |
| * object wrapper set in |
| * {@link WrappingTemplateModel#setDefaultObjectWrapper(ObjectWrapper)}. |
| * @param collection the collection containing initial values. Note that a |
| * copy of the collection is made for internal use. |
| * |
| * @deprecated Use {@link #SimpleSequence(Collection, ObjectWrapper)}. |
| */ |
| @Deprecated |
| public SimpleSequence(Collection collection) { |
| this(collection, null); |
| } |
| |
| /** |
| * Constructs a simple sequence from the passed collection model, which shouldn't be added to later. The internal |
| * list will be build immediately (not lazily). The resulting sequence shouldn't be extended with |
| * {@link #add(Object)}, because the appropriate {@link ObjectWrapper} won't be available; use |
| * {@link #SimpleSequence(Collection, ObjectWrapper)} instead, if you need that. |
| */ |
| public SimpleSequence(TemplateCollectionModel tcm) throws TemplateModelException { |
| ArrayList alist = new ArrayList(); |
| for (TemplateModelIterator it = tcm.iterator(); it.hasNext(); ) { |
| alist.add(it.next()); |
| } |
| alist.trimToSize(); |
| list = alist; |
| } |
| |
| /** |
| * Constructs an empty sequence using the specified object wrapper. |
| * |
| * @param wrapper |
| * The object wrapper to use to wrap the list items into {@link TemplateModel} instances. {@code null} is |
| * allowed, but deprecated, and will cause the deprecated default object wrapper (set in |
| * {@link WrappingTemplateModel#setDefaultObjectWrapper(ObjectWrapper)}) to be used. |
| */ |
| public SimpleSequence(ObjectWrapper wrapper) { |
| super(wrapper); |
| list = new ArrayList(); |
| } |
| |
| /** |
| * Constructs an empty simple sequence with preallocated capacity. |
| * |
| * @param wrapper |
| * See the similar parameter of {@link SimpleSequence#SimpleSequence(ObjectWrapper)}. |
| * |
| * @since 2.3.21 |
| */ |
| public SimpleSequence(int capacity, ObjectWrapper wrapper) { |
| super(wrapper); |
| list = new ArrayList(capacity); |
| } |
| |
| /** |
| * Constructs a simple sequence that will contain the elements from the specified {@link Collection}; consider |
| * using {@link DefaultListAdapter} instead. |
| * |
| * @param collection |
| * The collection containing the initial items of the sequence. A shallow copy of this collection is made |
| * immediately for internal use (thus, later modification on the parameter collection won't be visible in |
| * the resulting sequence). The items however, will be only wrapped with the {@link ObjectWrapper} |
| * lazily, when first needed. |
| * @param wrapper |
| * See the similar parameter of {@link SimpleSequence#SimpleSequence(ObjectWrapper)}. |
| */ |
| public SimpleSequence(Collection collection, ObjectWrapper wrapper) { |
| super(wrapper); |
| list = new ArrayList(collection); |
| } |
| |
| /** |
| * Adds an arbitrary object to the end of this sequence. If the newly added object does not implement the |
| * {@link TemplateModel} interface, it will be wrapped into the appropriate {@link TemplateModel} interface when |
| * it's first read (lazily). |
| * |
| * @param obj |
| * The object to be added. |
| */ |
| public void add(Object obj) { |
| list.add(obj); |
| unwrappedList = null; |
| } |
| |
| /** |
| * Adds a boolean value to the end of this sequence. The newly added boolean will be immediately converted into |
| * {@link TemplateBooleanModel#TRUE} or {@link TemplateBooleanModel#FALSE}, without using the {@link ObjectWrapper}. |
| * |
| * @param b |
| * The boolean value to be added. |
| * |
| * @deprecated Use {@link #add(Object)} instead, as this bypasses the {@link ObjectWrapper}. |
| */ |
| @Deprecated |
| public void add(boolean b) { |
| add(b ? TemplateBooleanModel.TRUE : TemplateBooleanModel.FALSE); |
| } |
| |
| /** |
| * Builds a deep-copy of the underlying list, unwrapping any values that were already converted to |
| * {@link TemplateModel}-s. When called for the second time (or later), it just reuses the first result, unless the |
| * sequence was modified since then. |
| * |
| * @deprecated No replacement exists; not a reliable way of getting back the original list elemnts. |
| */ |
| @Deprecated |
| public List toList() throws TemplateModelException { |
| if (unwrappedList == null) { |
| Class listClass = list.getClass(); |
| List result = null; |
| try { |
| result = (List) listClass.newInstance(); |
| } catch (Exception e) { |
| throw new TemplateModelException("Error instantiating an object of type " + listClass.getName(), |
| e); |
| } |
| BeansWrapper bw = BeansWrapper.getDefaultInstance(); |
| for (int i = 0; i < list.size(); i++) { |
| Object elem = list.get(i); |
| if (elem instanceof TemplateModel) { |
| elem = bw.unwrap((TemplateModel) elem); |
| } |
| result.add(elem); |
| } |
| unwrappedList = result; |
| } |
| return unwrappedList; |
| } |
| |
| /** |
| * Returns the item at the specified index of the list. If the item isn't yet an {@link TemplateModel}, it will wrap |
| * it to one now, and writes it back into the backing list. |
| */ |
| @Override |
| public TemplateModel get(int index) throws TemplateModelException { |
| try { |
| Object value = list.get(index); |
| if (value instanceof TemplateModel) { |
| return (TemplateModel) value; |
| } |
| TemplateModel tm = wrap(value); |
| list.set(index, tm); |
| return tm; |
| } catch (IndexOutOfBoundsException e) { |
| return null; |
| } |
| } |
| |
| @Override |
| public int size() { |
| return list.size(); |
| } |
| |
| /** |
| * @return a synchronized wrapper for list. |
| */ |
| public SimpleSequence synchronizedWrapper() { |
| return new SynchronizedSequence(); |
| } |
| |
| @Override |
| public String toString() { |
| return list.toString(); |
| } |
| |
| private class SynchronizedSequence extends SimpleSequence { |
| private SynchronizedSequence() { |
| super(SimpleSequence.this.getObjectWrapper()); |
| } |
| |
| @Override |
| public void add(Object obj) { |
| synchronized (SimpleSequence.this) { |
| SimpleSequence.this.add(obj); |
| } |
| } |
| |
| @Override |
| public TemplateModel get(int i) throws TemplateModelException { |
| synchronized (SimpleSequence.this) { |
| return SimpleSequence.this.get(i); |
| } |
| } |
| |
| @Override |
| public int size() { |
| synchronized (SimpleSequence.this) { |
| return SimpleSequence.this.size(); |
| } |
| } |
| |
| @Override |
| public List toList() throws TemplateModelException { |
| synchronized (SimpleSequence.this) { |
| return SimpleSequence.this.toList(); |
| } |
| } |
| |
| @Override |
| public SimpleSequence synchronizedWrapper() { |
| return this; |
| } |
| } |
| |
| } |