Package org.apache.tomcat.util.http

Class WebdavIfHeader

java.lang.Object

org.apache.tomcat.util.http.WebdavIfHeader

public class WebdavIfHeader
extends Object

The IfHeader class represents the state lists defined through the HTTP If header, which is specified in RFC 2518 as follows :

    If = "If" ":" ( 1*No-tag-list | 1*Tagged-list)
    No-tag-list = List
    Tagged-list = Resource 1*List
    Resource = Coded-URL
    List = "(" 1*(["Not"](State-etag | "[" entity-tag "]")) ")"
    State-etag = Coded-URL
    Coded-URL = "<" absoluteURI ">"
 

Reformulating this specification into proper EBNF as specified by N. Wirth we get the following productions, which map to the parse METHODS of this class. Any whitespace is ignored except for white space surrounding and within words which is considered significant.

    If = "If:" ( Tagged | Untagged ).
    Tagged = { "<" Word ">" Untagged } .
    Untagged = { "(" IfList ")" } .
    IfList = { [ "Not" ] ( ("<" Word ">" ) | ( "[" Word "]" ) ) } .
    Word = characters .
 

An If header either contains untagged IfList entries or tagged IfList entries but not a mixture of both. An If header containing tagged entries is said to be of tagged type while an If header containing untagged entries is said to be of untagged type.

An IfList is a list of tokens - words enclosed in < > - and etags - words enclosed in [ ]. An IfList matches a (token, etag) tuple if all entries in the list match. If an entry in the list is prefixed with the word Not (parsed case insensitively) the entry must not match the concrete token or etag.

Example: The ifList (<token> [etag]) only matches if the concret token has the value token and the conrete etag has the value etag. On the other hand, the ifList (Not <notoken>) matches any token which is not notoken (in this case the concrete value of the etag is not taken into consideration). This class was contributed by Apache Jackrabbit

Author:

Felix Meschberger

Constructor Summary

Constructors

Constructor	Description
WebdavIfHeader(String[] tokens)	Create a Untagged IfHeader if the given lock tokens.
WebdavIfHeader(String uriPrefix, String ifHeaderValue)	Parses the If header and creates and internal representation which is easy to query.

Method Summary

Modifier and Type	Method	Description
Iterator<String>	getAllNotTokens()
Iterator<String>	getAllTokens()
String	getHeaderName()
String	getHeaderValue()	Return the String representation of the If header present on the given request or null.
Iterator<String>	getResources()
boolean	hasValue()	Returns true if an If header was present in the given request.
boolean	matches(String tag, List<String> tokens, String etag)	Tries to match the contents of the If header with the given token and etag values with the restriction to only check for the tag.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

WebdavIfHeader

public WebdavIfHeader(String[] tokens)
               throws IOException

Create a Untagged IfHeader if the given lock tokens.

Parameters:

tokens - the tokens

Throws:

IOException - If the parsing of the IfHeader fails

WebdavIfHeader

public WebdavIfHeader(String uriPrefix,
 String ifHeaderValue)
               throws IOException

Parses the If header and creates and internal representation which is easy to query.

Parameters:

uriPrefix - The uri prefix to use for the absolute href

ifHeaderValue - the if header

Throws:

IOException - If the parsing of the IfHeader fails

Method Details

getHeaderName

public String getHeaderName()

Returns:

If String.

getHeaderValue

public String getHeaderValue()

Return the String representation of the If header present on the given request or null.

Returns:

If header value as String or null.

hasValue

public boolean hasValue()

Returns true if an If header was present in the given request. False otherwise.

Returns:

true if an If header was present.

matches

public boolean matches(String tag,
 List<String> tokens,
 String etag)

Tries to match the contents of the If header with the given token and etag values with the restriction to only check for the tag.

If the If header is of untagged type, the untagged IfList is matched against the token and etag given: A match of the token and etag is found if at least one of the IfList entries match the token and etag tuple.

Parameters:

tag - The tag to identify the IfList to match the token and etag against.

tokens - The tokens to compare.

etag - The ETag value to compare.

Returns:

If the If header is of untagged type the result is true if any of the IfList entries matches the token and etag values. For tagged type If header the result is true if either no entry for the given tag exists in the If header or if the IfList for the given tag matches the token and etag given.

getResources

public Iterator<String> getResources()

Returns:

an iterator over all resources present in the if header.

getAllTokens

public Iterator<String> getAllTokens()

Returns:

an iterator over all tokens present in the if header, that were not denied by a leading NOT statement.

getAllNotTokens

public Iterator<String> getAllNotTokens()

Returns:

an iterator over all NOT tokens present in the if header, that were explicitly denied.