/*
* ====================================================================
* 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apache.http.message;
import java.util.
NoSuchElementException;
import org.apache.http.
Header;
import org.apache.http.
HeaderIterator;
import org.apache.http.util.
Args;
/**
* Basic implementation of a {@link HeaderIterator}.
*
* @since 4.0
*/
public class
BasicHeaderIterator implements
HeaderIterator {
/**
* An array of headers to iterate over.
* Not all elements of this array are necessarily part of the iteration.
* This array will never be modified by the iterator.
* Derived implementations are expected to adhere to this restriction.
*/
protected final
Header[]
allHeaders;
/**
* The position of the next header in {@link #allHeaders allHeaders}.
* Negative if the iteration is over.
*/
protected int
currentIndex;
/**
* The header name to filter by.
* {@code null} to iterate over all headers in the array.
*/
protected
String headerName;
/**
* Creates a new header iterator.
*
* @param headers an array of headers over which to iterate
* @param name the name of the headers over which to iterate, or
* {@code null} for any
*/
public
BasicHeaderIterator(final
Header[]
headers, final
String name) {
super();
this.
allHeaders =
Args.
notNull(
headers, "Header array");
this.
headerName =
name;
this.
currentIndex =
findNext(-1);
}
/**
* Determines the index of the next header.
*
* @param pos one less than the index to consider first,
* -1 to search for the first header
*
* @return the index of the next header that matches the filter name,
* or negative if there are no more headers
*/
protected int
findNext(final int
pos) {
int
from =
pos;
if (
from < -1) {
return -1;
}
final int
to = this.
allHeaders.length-1;
boolean
found = false;
while (!
found && (
from <
to)) {
from++;
found =
filterHeader(
from);
}
return
found ?
from : -1;
}
/**
* Checks whether a header is part of the iteration.
*
* @param index the index of the header to check
*
* @return {@code true} if the header should be part of the
* iteration, {@code false} to skip
*/
protected boolean
filterHeader(final int
index) {
return (this.
headerName == null) ||
this.
headerName.
equalsIgnoreCase(this.
allHeaders[
index].
getName());
}
// non-javadoc, see interface HeaderIterator
@
Override
public boolean
hasNext() {
return (this.
currentIndex >= 0);
}
/**
* Obtains the next header from this iteration.
*
* @return the next header in this iteration
*
* @throws NoSuchElementException if there are no more headers
*/
@
Override
public
Header nextHeader()
throws
NoSuchElementException {
final int
current = this.
currentIndex;
if (
current < 0) {
throw new
NoSuchElementException("Iteration already finished.");
}
this.
currentIndex =
findNext(
current);
return this.
allHeaders[
current];
}
/**
* Returns the next header.
* Same as {@link #nextHeader nextHeader}, but not type-safe.
*
* @return the next header in this iteration
*
* @throws NoSuchElementException if there are no more headers
*/
@
Override
public final
Object next()
throws
NoSuchElementException {
return
nextHeader();
}
/**
* Removing headers is not supported.
*
* @throws UnsupportedOperationException always
*/
@
Override
public void
remove()
throws
UnsupportedOperationException {
throw new
UnsupportedOperationException
("Removing headers is not supported.");
}
}