/*
* 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 org.apache.tomcat.util.collections;
import org.apache.tomcat.util.buf.MessageBytes;
// Originally MimeHeaders
/**
* An efficient representation for certain type of map. The keys
* can have a single or multi values, but most of the time there are
* single values.
*
* The data is of "MessageBytes" type, meaning bytes[] that can be
* converted to Strings ( if needed, and encoding is lazy-binded ).
*
* This is a base class for MimeHeaders, Parameters and Cookies.
*
* Data structures: each field is a single-valued key/value.
* The fields are allocated when needed, and are recycled.
* The current implementation does linear search, in future we'll
* also use the hashkey.
*
* @author dac@eng.sun.com
* @author James Todd [gonzo@eng.sun.com]
* @author Costin Manolache
*/
public class MultiMap {
protected Field[] fields;
// fields in use
protected int count;
/**
*
*/
public MultiMap(int initial_size) {
fields=new Field[initial_size];
}
/**
* Clears all header fields.
*/
public void recycle() {
for (int i = 0; i < count; i++) {
fields[i].recycle();
}
count = 0;
}
// -------------------- Idx access to headers ----------
// This allows external iterators.
/**
* Returns the current number of header fields.
*/
public int size() {
return count;
}
/**
* Returns the Nth header name
* This may be used to iterate through all header fields.
*
* An exception is thrown if the index is not valid ( <0 or >size )
*/
public MessageBytes getName(int n) {
// n >= 0 && n < count ? headers[n].getName() : null
return fields[n].name;
}
/**
* Returns the Nth header value
* This may be used to iterate through all header fields.
*/
public MessageBytes getValue(int n) {
return fields[n].value;
}
/** Find the index of a field with the given name.
*/
public int find( String name, int starting ) {
// We can use a hash - but it's not clear how much
// benefit you can get - there is an overhead
// and the number of headers is small (4-5 ?)
// Another problem is that we'll pay the overhead
// of constructing the hashtable
// A custom search tree may be better
for (int i = starting; i < count; i++) {
if (fields[i].name.equals(name)) {
return i;
}
}
return -1;
}
/** Find the index of a field with the given name.
*/
public int findIgnoreCase( String name, int starting ) {
// We can use a hash - but it's not clear how much
// benefit you can get - there is an overhead
// and the number of headers is small (4-5 ?)
// Another problem is that we'll pay the overhead
// of constructing the hashtable
// A custom search tree may be better
for (int i = starting; i < count; i++) {
if (fields[i].name.equalsIgnoreCase(name)) {
return i;
}
}
return -1;
}
/**
* Removes the field at the specified position.
*
* MultiMap will preserve the order of field add unless remove()
* is called. This is not thread-safe, and will invalidate all
* iterators.
*
* This is not a frequent operation for Headers and Parameters -
* there are better ways ( like adding a "isValid" field )
*/
public void remove( int i ) {
// reset and swap with last header
Field mh = fields[i];
// reset the field
mh.recycle();
fields[i] = fields[count - 1];
fields[count - 1] = mh;
count--;
}
/** Create a new, unitialized entry.
*/
public int addField() {
int len = fields.length;
int pos=count;
if (count >= len) {
// expand header list array
Field tmp[] = new Field[pos * 2];
System.arraycopy(fields, 0, tmp, 0, len);
fields = tmp;
}
if (fields[pos] == null) {
fields[pos] = new Field();
}
count++;
return pos;
}
public MessageBytes get( String name) {
for (int i = 0; i < count; i++) {
if (fields[i].name.equals(name)) {
return fields[i].value;
}
}
return null;
}
public int findFirst( String name ) {
for (int i = 0; i < count; i++) {
if (fields[i].name.equals(name)) {
return i;
}
}
return -1;
}
public int findNext( int startPos ) {
int next= fields[startPos].nextPos;
if( next != MultiMap.NEED_NEXT ) {
return next;
}
// next==NEED_NEXT, we never searched for this header
MessageBytes name=fields[startPos].name;
for (int i = startPos; i < count; i++) {
if (fields[i].name.equals(name)) {
// cache the search result
fields[startPos].nextPos=i;
return i;
}
}
fields[startPos].nextPos= MultiMap.LAST;
return -1;
}
// workaround for JDK1.1.8/solaris
static final int NEED_NEXT=-2;
static final int LAST=-1;
// -------------------- Internal representation --------------------
final class Field {
MessageBytes name;
MessageBytes value;
// Extra info for speed
// multiple fields with same name - a linked list will
// speed up multiple name enumerations and search.
int nextPos;
// hashkey
int hash;
Field nextSameHash;
Field() {
nextPos=MultiMap.NEED_NEXT;
}
void recycle() {
name.recycle();
value.recycle();
nextPos=MultiMap.NEED_NEXT;
}
}
}
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