/*
* Copyright 2015 The Netty Project
*
* The Netty Project 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 io.netty.handler.codec;
import java.util.AbstractList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
import static io.netty.util.internal.ObjectUtil.checkNotNull;
/**
* Provides utility methods related to {@link Headers}.
*/
public final class HeadersUtils {
private HeadersUtils() {
}
/**
* {@link Headers#get(Object)} and convert each element of {@link List} to a {@link String}.
* @param name the name of the header to retrieve
* @return a {@link List} of header values or an empty {@link List} if no values are found.
*/
public static <K, V> List<String> getAllAsString(Headers<K, V, ?> headers, K name) {
final List<V> allNames = headers.getAll(name);
return new AbstractList<String>() {
@Override
public String get(int index) {
V value = allNames.get(index);
return value != null ? value.toString() : null;
}
@Override
public int size() {
return allNames.size();
}
};
}
/**
* {@link Headers#get(Object)} and convert the result to a {@link String}.
* @param headers the headers to get the {@code name} from
* @param name the name of the header to retrieve
* @return the first header value if the header is found. {@code null} if there's no such entry.
*/
public static <K, V> String getAsString(Headers<K, V, ?> headers, K name) {
V orig = headers.get(name);
return orig != null ? orig.toString() : null;
}
/**
* {@link Headers#iterator()} which converts each {@link Entry}'s key and value to a {@link String}.
*/
public static Iterator<Entry<String, String>> iteratorAsString(
Iterable<Entry<CharSequence, CharSequence>> headers) {
return new StringEntryIterator(headers.iterator());
}
/**
* {@link Headers#names()} and convert each element of {@link Set} to a {@link String}.
* @param headers the headers to get the names from
* @return a {@link Set} of header values or an empty {@link Set} if no values are found.
*/
public static Set<String> namesAsString(Headers<CharSequence, CharSequence, ?> headers) {
return new CharSequenceDelegatingStringSet(headers.names());
}
private static final class StringEntryIterator implements Iterator<Entry<String, String>> {
private final Iterator<Entry<CharSequence, CharSequence>> iter;
public StringEntryIterator(Iterator<Entry<CharSequence, CharSequence>> iter) {
this.iter = iter;
}
@Override
public boolean hasNext() {
return iter.hasNext();
}
@Override
public Entry<String, String> next() {
return new StringEntry(iter.next());
}
@Override
public void remove() {
iter.remove();
}
}
private static final class StringEntry implements Entry<String, String> {
private final Entry<CharSequence, CharSequence> entry;
private String name;
private String value;
StringEntry(Entry<CharSequence, CharSequence> entry) {
this.entry = entry;
}
@Override
public String getKey() {
if (name == null) {
name = entry.getKey().toString();
}
return name;
}
@Override
public String getValue() {
if (value == null && entry.getValue() != null) {
value = entry.getValue().toString();
}
return value;
}
@Override
public String setValue(String value) {
String old = getValue();
entry.setValue(value);
return old;
}
@Override
public String toString() {
return entry.toString();
}
}
private static final class StringIterator<T> implements Iterator<String> {
private final Iterator<T> iter;
public StringIterator(Iterator<T> iter) {
this.iter = iter;
}
@Override
public boolean hasNext() {
return iter.hasNext();
}
@Override
public String next() {
T next = iter.next();
return next != null ? next.toString() : null;
}
@Override
public void remove() {
iter.remove();
}
}
private static final class CharSequenceDelegatingStringSet extends DelegatingStringSet<CharSequence> {
public CharSequenceDelegatingStringSet(Set<CharSequence> allNames) {
super(allNames);
}
@Override
public boolean add(String e) {
return allNames.add(e);
}
@Override
public boolean addAll(Collection<? extends String> c) {
return allNames.addAll(c);
}
}
private abstract static class DelegatingStringSet<T> implements Set<String> {
protected final Set<T> allNames;
public DelegatingStringSet(Set<T> allNames) {
this.allNames = checkNotNull(allNames, "allNames");
}
@Override
public int size() {
return allNames.size();
}
@Override
public boolean isEmpty() {
return allNames.isEmpty();
}
@Override
public boolean contains(Object o) {
return allNames.contains(o.toString());
}
@Override
public Iterator<String> iterator() {
return new StringIterator<T>(allNames.iterator());
}
@Override
public Object[] toArray() {
Object[] arr = new Object[size()];
fillArray(arr);
return arr;
}
@SuppressWarnings("unchecked")
@Override
public <X> X[] toArray(X[] a) {
if (a == null || a.length < size()) {
X[] arr = (X[]) new Object[size()];
fillArray(arr);
return arr;
}
fillArray(a);
return a;
}
private void fillArray(Object[] arr) {
Iterator<T> itr = allNames.iterator();
for (int i = 0; i < size(); ++i) {
arr[i] = itr.next();
}
}
@Override
public boolean remove(Object o) {
return allNames.remove(o);
}
@Override
public boolean containsAll(Collection<?> c) {
for (Object o : c) {
if (!contains(o)) {
return false;
}
}
return true;
}
@Override
public boolean removeAll(Collection<?> c) {
boolean modified = false;
for (Object o : c) {
if (remove(o)) {
modified = true;
}
}
return modified;
}
@Override
public boolean retainAll(Collection<?> c) {
boolean modified = false;
Iterator<String> it = iterator();
while (it.hasNext()) {
if (!c.contains(it.next())) {
it.remove();
modified = true;
}
}
return modified;
}
@Override
public void clear() {
allNames.clear();
}
}
}