org.eclipse.osgi.framework.internal.core
Class FilterImpl

java.lang.Object
  org.eclipse.osgi.framework.internal.core.FilterImpl

All Implemented Interfaces:

Filter

public class FilterImpl
extends java.lang.Object
implements Filter

RFC 1960-based Filter. Filter objects can be created by calling the constructor with the desired filter string. A Filter object can be called numerous times to determine if the match argument matches the filter string that was used to create the Filter object.

The syntax of a filter string is the string representation of LDAP search filters as defined in RFC 1960: A String Representation of LDAP Search Filters (available at http://www.ietf.org/rfc/rfc1960.txt). It should be noted that RFC 2254: A String Representation of LDAP Search Filters (available at http://www.ietf.org/rfc/rfc2254.txt) supersedes RFC 1960 but only adds extensible matching and is not applicable for this API.

The string representation of an LDAP search filter is defined by the following grammar. It uses a prefix format.

   <filter> ::= '(' <filtercomp> ')'
   <filtercomp> ::= <and> | <or> | <not> | <item>
   <and> ::= '&' <filterlist>
   <or> ::= '|' <filterlist>
   <not> ::= '!' <filter>
   <filterlist> ::= <filter> | <filter> <filterlist>
   <item> ::= <simple> | <present> | <substring>
   <simple> ::= <attr> <filtertype> <value>
   <filtertype> ::= <equal> | <approx> | <greater> | <less>
   <equal> ::= '='
   <approx> ::= '~='
   <greater> ::= '>='
   <less> ::= '<='
   <present> ::= <attr> '=*'
   <substring> ::= <attr> '=' <initial> <any> <final>
   <initial> ::= NULL | <value>
   <any> ::= '*' <starval>
   <starval> ::= NULL | <value> '*' <starval>
   <final> ::= NULL | <value>
 

<attr> is a string representing an attribute, or key, in the properties objects of the registered services. Attribute names are not case sensitive; that is cn and CN both refer to the same attribute. <value> is a string representing the value, or part of one, of a key in the properties objects of the registered services. If a <value> must contain one of the characters '*' or '(' or ')', these characters should be escaped by preceding them with the backslash '\' character. Note that although both the <substring> and <present> productions can produce the 'attr=*' construct, this construct is used only to denote a presence filter.

Examples of LDAP filters are:

   "(cn=Babs Jensen)"
   "(!(cn=Tim Howes))"
   "(&(" + Constants.OBJECTCLASS + "=Person)(|(sn=Jensen)(cn=Babs J*)))"
   "(o=univ*of*mich*)"
 

The approximate match (~=) is implementation specific but should at least ignore case and white space differences. Optional are codes like soundex or other smart "closeness" comparisons.

Comparison of values is not straightforward. Strings are compared differently than numbers and it is possible for a key to have multiple values. Note that that keys in the match argument must always be strings. The comparison is defined by the object type of the key's value. The following rules apply for comparison:

Property Value Type	Comparison Type
String	String comparison
Integer, Long, Float, Double, Byte, Short, BigInteger, BigDecimal	numerical comparison
Character	character comparison
Boolean	equality comparisons only
[] (array)	recursively applied to values
Vector	recursively applied to elements

Note: arrays of primitives are also supported.

A filter matches a key that has multiple values if it matches at least one of those values. For example,

   Dictionary d = new Hashtable();
   d.put( "cn", new String[] { "a", "b", "c" } );
 

d will match (cn=a) and also (cn=b)

A filter component that references a key having an unrecognizable data type will evaluate to false .

Method Summary

boolean	equals(java.lang.Object obj) Compares this Filter object to another object.
java.lang.String[]	getAttributes() Returns all the attributes contained within this filter
java.lang.String	getRequiredObjectClass() Returns the leftmost required objectClass value for the filter to evaluate to true.
int	hashCode() Returns the hashCode for this Filter object.
boolean	match(java.util.Dictionary dictionary) Filter using a Dictionary object.
boolean	match(ServiceReference reference) Filter using a service's properties.
boolean	matchCase(java.util.Dictionary dictionary) Filter with case sensitivity using a Dictionary object.
static FilterImpl	newInstance(java.lang.String filterString) Constructs a FilterImpl object.
java.lang.String	toString() Returns this Filter object's filter string.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

newInstance

public static FilterImpl newInstance(java.lang.String filterString)
                              throws InvalidSyntaxException

Constructs a FilterImpl object. This filter object may be used to match a ServiceReferenceImpl or a Dictionary.

If the filter cannot be parsed, an InvalidSyntaxException will be thrown with a human readable message where the filter became unparsable.

Parameters:

filterString - the filter string.

Throws:

InvalidSyntaxException - If the filter parameter contains an invalid filter string that cannot be parsed.

match

public boolean match(ServiceReference reference)

Filter using a service's properties.

The filter is executed using the keys and values of the referenced service's properties. The keys are case insensitively matched with the filter.

Specified by:

match in interface Filter

Parameters:

reference - The reference to the service whose properties are used in the match.

Returns:

true if the service's properties match this filter; false otherwise.

match

public boolean match(java.util.Dictionary dictionary)

Filter using a Dictionary object. The Filter is executed using the Dictionary object's keys and values. The keys are case insensitively matched with the filter.

Specified by:

match in interface Filter

Parameters:

dictionary - The Dictionary object whose keys are used in the match.

Returns:

true if the Dictionary object's keys and values match this filter; false otherwise.

Throws:

java.lang.IllegalArgumentException - If dictionary contains case variants of the same key name.

matchCase

public boolean matchCase(java.util.Dictionary dictionary)

Filter with case sensitivity using a Dictionary object. The Filter is executed using the Dictionary object's keys and values. The keys are case sensitively matched with the filter.

Specified by:

matchCase in interface Filter

Parameters:

dictionary - The Dictionary object whose keys are used in the match.

Returns:

true if the Dictionary object's keys and values match this filter; false otherwise.

Since:

1.3

toString

public java.lang.String toString()

Returns this Filter object's filter string.

The filter string is normalized by removing whitespace which does not affect the meaning of the filter.

Specified by:

toString in interface Filter

Overrides:

toString in class java.lang.Object

Returns:

Filter string.

equals

public boolean equals(java.lang.Object obj)

Compares this Filter object to another object.

Specified by:

equals in interface Filter

Overrides:

equals in class java.lang.Object

Parameters:

obj - The object to compare against this Filter object.

Returns:

If the other object is a Filter object, then returns this.toString().equals(obj.toString(); false otherwise.

hashCode

public int hashCode()

Returns the hashCode for this Filter object.

Specified by:

hashCode in interface Filter

Overrides:

hashCode in class java.lang.Object

Returns:

The hashCode of the filter string; that is, this.toString().hashCode().

getRequiredObjectClass

public java.lang.String getRequiredObjectClass()

Returns the leftmost required objectClass value for the filter to evaluate to true.

Returns:

The leftmost required objectClass value or null if none could be determined.

getAttributes

public java.lang.String[] getAttributes()

Returns all the attributes contained within this filter

Returns:

all the attributes contained within this filter