org.simpleframework.http.parse.LanguageParser Maven / Gradle / Ivy
/*
* LanguageParser.java February 2001
*
* Copyright (C) 2001, Niall Gallagher
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA
*/
package org.simpleframework.http.parse;
import java.util.List;
import java.util.Locale;
/**
* LanguageParser is used to parse the HTTP Accept-Language
* header. This takes in an Accept-Language header and parses
* it according the RFC 2616 BNF for the Accept-Language header.
* This also has the ability to sequence the language tokens in terms of
* the most preferred and the least preferred.
*
* This uses the qvalues outlined by RFC 2616 to order the language tokens
* by preference. Typically the language tokens will not have qvalues with
* the language. However when a language tag has the qvalue parameter then
* this tag will be ordered based on the value of that parameter. A language
* tag without the qvalue parameter is considered to have a qvalue of 1 and
* is ordered accordingly.
*
* @author Niall Gallagher
*/
public class LanguageParser extends ListParser {
/**
* This is used to create a LanguageParser for the
* Accept-Language HTTP header value. This will
* parse a set of language tokens and there parameters. The
* languages will be ordered on preference. This constructor
* will parse the value given using parse(String).
*/
public LanguageParser() {
super();
}
/**
* This is used to create a LanguageParser for the
* Accept-Language HTTP header value. This will
* parse a set of language tokens and there parameters. The
* languages will be ordered on preference. This constructor
* will parse the value given using parse(String).
*
* @param text value of a Accept-Language header
*/
public LanguageParser(String text) {
super(text);
}
/**
* This is used to create a LanguageParser for the
* Accept-Language HTTP header value. This will
* parse a set of language tokens and there parameters. The
* languages will be ordered on preference. This constructor
* will parse the value given using parse(String).
*
* @param list value of a Accept-Language header
*/
public LanguageParser(List list) {
super(list);
}
/**
* This creates a locale object using an offset and a length.
* The locale is created from the extracted token and the offset
* and length ensure that no leading or trailing whitespace are
* within the created locale object.
*
* @param text this is the text buffer to acquire the value from
* @param start the offset within the array to take characters
* @param len this is the number of characters within the token
*/
@Override
protected Locale create(char[] text, int start, int len){
String language = language(text, start, len);
String country = country(text, start, len);
return new Locale(language, country);
}
/**
* This will extract the primary language tag from the header.
* This token is used to represent the language that will be
* available in the Locale object created.
*
* @param text this is the text buffer to acquire the value from
* @param start the offset within the array to take characters
* @param len this is the number of characters within the token
*/
private String language(char[] text, int start, int len) {
int mark = start;
int size = 0;
while(start < len) {
char next = text[start];
if(terminal(next)) {
return new String(text, mark, size);
}
size++;
start++;
}
return new String(text, mark, len);
}
/**
* This will extract the primary country tag from the header.
* This token is used to represent the country that will be
* available in the Locale object created.
*
* @param text this is the text buffer to acquire the value from
* @param start the offset within the array to take characters
* @param len this is the number of characters within the token
*/
private String country(char[] text, int start, int len) {
int size = len;
while(start < len) {
if(text[start++] == '-') {
return new String(text, start, --size);
}
size--;
}
return "";
}
/**
* This is used to determine whether the character provided is
* a terminal character. The terminal token is the value that is
* used to separate the country from the language and also any
* character the marks the end of the language token.
*
* @param ch this is the character that is to be evaluated
*
* @return true if the character represents a terminal token
*/
private boolean terminal(char ch) {
return ch ==' ' || ch == '-' || ch == ';';
}
}