freemarker.template.utility.TemplateModelUtils Maven / Gradle / Ivy
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/*
* 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.utility;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import freemarker.core.CollectionAndSequence;
import freemarker.core._MessageUtil;
import freemarker.template.Configuration;
import freemarker.template.ObjectWrapper;
import freemarker.template.SimpleSequence;
import freemarker.template.TemplateCollectionModel;
import freemarker.template.TemplateHashModel;
import freemarker.template.TemplateHashModelEx;
import freemarker.template.TemplateHashModelEx2;
import freemarker.template.TemplateHashModelEx2.KeyValuePair;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;
import freemarker.template.TemplateModelIterator;
import freemarker.template.TemplateScalarModel;
import freemarker.template._TemplateAPI;
/**
* Static utility method related to {@link TemplateModel}-s that didn't fit elsewhere.
*
* @since 2.3.28
*/
public final class TemplateModelUtils {
// Private to prevent instantiation
private TemplateModelUtils() {
// no op.
}
/**
* {@link TemplateHashModelExKeyValuePairIterator} that even works for a non-{@link TemplateHashModelEx2}
* {@link TemplateHashModelEx}. This is used to simplify code that needs to iterate through the key-value pairs of
* {@link TemplateHashModelEx}-s, as with this you don't have to handle non-{@link TemplateHashModelEx2}-s
* separately. For non-{@link TemplateHashModelEx2} values the iteration will throw {@link TemplateModelException}
* if it reaches a key that's not a string ({@link TemplateScalarModel}).
*
* @since 2.3.28
*/
public static final TemplateHashModelEx2.KeyValuePairIterator getKeyValuePairIterator(TemplateHashModelEx hash)
throws TemplateModelException {
return hash instanceof TemplateHashModelEx2 ? ((TemplateHashModelEx2) hash).keyValuePairIterator()
: new TemplateHashModelExKeyValuePairIterator(hash);
}
private static class TemplateHashModelExKeyValuePairIterator implements TemplateHashModelEx2.KeyValuePairIterator {
private final TemplateHashModelEx hash;
private final TemplateModelIterator keyIter;
private TemplateHashModelExKeyValuePairIterator(TemplateHashModelEx hash) throws TemplateModelException {
this.hash = hash;
keyIter = hash.keys().iterator();
}
@Override
public boolean hasNext() throws TemplateModelException {
return keyIter.hasNext();
}
@Override
public KeyValuePair next() throws TemplateModelException {
final TemplateModel key = keyIter.next();
if (!(key instanceof TemplateScalarModel)) {
throw _MessageUtil.newKeyValuePairListingNonStringKeyExceptionMessage(key, hash);
}
return new KeyValuePair() {
@Override
public TemplateModel getKey() throws TemplateModelException {
return key;
}
@Override
public TemplateModel getValue() throws TemplateModelException {
return hash.get(((TemplateScalarModel) key).getAsString());
}
};
}
}
/**
* Same as {@link #wrapAsHashUnion(ObjectWrapper, List)}, but uses a varargs parameter instead of a {@link List}.
*
* @since 2.3.29
*/
public static TemplateHashModel wrapAsHashUnion(ObjectWrapper objectWrapper, Object... hashLikeObjects)
throws TemplateModelException {
return wrapAsHashUnion(objectWrapper, Arrays.asList(hashLikeObjects));
}
/**
* Creates a {@link TemplateHashModel} that is the union of the hash-like objects passed in as argument. Hash-like
* here means that the argument {@link ObjectWrapper} will wrap it into an {@link TemplateModel} that implements
* {@link TemplateHashModel}, or it's already a {@link TemplateHashModel}. (Typical hash-like objects are JavaBeans
* and {@link Map}-s, though it depends on the {@link ObjectWrapper}.)
*
*
* This method is typical used when you want to compose a data-model from multiple objects in a way so that their
* entries ({@link Map} key-value pairs, bean properties, etc.) appear together on the top level of the data-model.
* In such case, use the return value of this method as the combined data-model. Note that this functionality
* somewhat overlaps with {@link Configuration#setSharedVariables(Map)}; check if that fits your use case better.
*
* @param objectWrapper
* {@link ObjectWrapper} used to wrap the elements of {@code hashLikeObjects}, except those that are
* already {@link TemplateModel}-s. Usually, you should pass in {@link Configuration#getObjectWrapper()}
* here.
* @param hashLikeObjects
* Hash-like objects whose union the result hash will be. The content of these hash-like objects must not
* change, or else the behavior of the resulting hash can be erratic. If multiple hash-like object
* contains the same key, then the value from the last such hash-like object wins. The oder of keys is
* kept, with the keys of earlier hash-like object object coming first (even if their values were
* replaced by a later hash-like object). This argument can't be {@code null}, but the list can contain
* {@code null} elements, which will be silently ignored. The list can be empty, in which case the result
* is an empty hash.
*
* @return The {@link TemplateHashModel} that's the union of the objects provided. This is a "view", that delegates
* to the underlying hashes, not a copy. The object is not thread safe. If all elements in
* {@code hashLikeObjects} are {@link TemplateHashModelEx} objects (or if there are 0 elements), then the
* result will implement {@link TemplateHashModelEx} as well.
*
* @throws TemplateModelException
* If wrapping an element of {@code hashLikeObjects} fails with {@link TemplateModelException}, or if
* wrapping an element results in a {@link TemplateModel} that's not a {@link TemplateHashModel}, or if
* the element was already a {@link TemplateModel} that isn't a {@link TemplateHashModel}.
*
* @since 2.3.29
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public static TemplateHashModel wrapAsHashUnion(ObjectWrapper objectWrapper, List hashLikeObjects)
throws TemplateModelException {
NullArgumentException.check("hashLikeObjects", hashLikeObjects);
List hashes = new ArrayList<>(hashLikeObjects.size());
boolean allTHMEx = true;
for (Object hashLikeObject : hashLikeObjects) {
if (hashLikeObject == null) {
continue;
}
TemplateModel tm;
if (hashLikeObject instanceof TemplateModel) {
tm = (TemplateModel) hashLikeObject;
} else {
tm = objectWrapper.wrap(hashLikeObject);
}
if (!(tm instanceof TemplateHashModelEx)) {
allTHMEx = false;
if (!(tm instanceof TemplateHashModel)) {
throw new TemplateModelException(
"One of the objects of the hash union is not hash-like: "
+ ClassUtil.getFTLTypeDescription(tm));
}
}
hashes.add((TemplateHashModel) tm);
}
return hashes.isEmpty() ? Constants.EMPTY_HASH
: hashes.size() == 1 ? hashes.get(0)
: allTHMEx ? new HashExUnionModel((List) hashes)
: new HashUnionModel(hashes);
}
private static abstract class AbstractHashUnionModel implements TemplateHashModel {
protected final List hashes;
public AbstractHashUnionModel(List hashes) {
this.hashes = hashes;
}
@Override
public TemplateModel get(String key) throws TemplateModelException {
for (int i = hashes.size() - 1; i >= 0; i--) {
TemplateModel value = hashes.get(i).get(key);
if (value != null) {
return value;
}
}
return null;
}
@Override
public boolean isEmpty() throws TemplateModelException {
for (TemplateHashModel hash : hashes) {
if (!hash.isEmpty()) {
return false;
}
}
return true;
}
}
private static class HashUnionModel extends AbstractHashUnionModel {
HashUnionModel(List hashes) {
super(hashes);
}
}
private static final class HashExUnionModel extends AbstractHashUnionModel
implements TemplateHashModelEx {
private CollectionAndSequence keys;
private CollectionAndSequence values;
private HashExUnionModel(List hashes) {
super(hashes);
}
@Override
public int size() throws TemplateModelException {
initKeys();
return keys.size();
}
@Override
public TemplateCollectionModel keys() throws TemplateModelException {
initKeys();
return keys;
}
@Override
public TemplateCollectionModel values() throws TemplateModelException {
initValues();
return values;
}
private void initKeys() throws TemplateModelException {
if (keys == null) {
Set keySet = new HashSet<>();
SimpleSequence keySeq = new SimpleSequence(_TemplateAPI.SAFE_OBJECT_WRAPPER);
for (TemplateHashModelEx hash : hashes) {
addKeys(keySet, keySeq, hash);
}
keys = new CollectionAndSequence(keySeq);
}
}
private static void addKeys(Set keySet, SimpleSequence keySeq, TemplateHashModelEx hash)
throws TemplateModelException {
TemplateModelIterator it = hash.keys().iterator();
while (it.hasNext()) {
TemplateScalarModel tsm = (TemplateScalarModel) it.next();
if (keySet.add(tsm.getAsString())) {
// The first occurrence of the key decides the index;
// this is consistent with the behavior of java.util.LinkedHashSet.
keySeq.add(tsm);
}
}
}
private void initValues() throws TemplateModelException {
if (values == null) {
SimpleSequence seq = new SimpleSequence(size(), _TemplateAPI.SAFE_OBJECT_WRAPPER);
// Note: size() invokes initKeys() if needed.
int ln = keys.size();
for (int i = 0; i < ln; i++) {
seq.add(get(((TemplateScalarModel) keys.get(i)).getAsString()));
}
values = new CollectionAndSequence(seq);
}
}
}
}