org.apache.directory.server.xdbm.search

Interface Evaluator<N extends org.apache.directory.api.ldap.model.filter.ExprNode>

All Known Implementing Classes:

AndEvaluator, ApproximateEvaluator, BaseLevelScopeEvaluator, EmptyEvaluator, EqualityEvaluator, GreaterEqEvaluator, LeafEvaluator, LessEqEvaluator, NotEvaluator, OneLevelScopeEvaluator, OrEvaluator, PassThroughEvaluator, PresenceEvaluator, SubstringEvaluator, SubtreeScopeEvaluator

public interface Evaluator<N extends org.apache.directory.api.ldap.model.filter.ExprNode>

Evaluates candidate entries to see if they match a filter expression. Evaluators contain various overloads to the evaluate method. Often a developer working in this region of the code may wonder when to use one override verses another. The overload taking an IndexEntry argument is specifically suited for use when there is the possibility of multiple entry lookups from the master table. If the same candidate in the form of an IndexEntry is evaluated more then this overload is more efficient since it stores the looked up entry in the IndexEntry preventing multiple lookups. If the index entry is already populated with an entry object, and some evaluation is required then it is preferrable to use the overload that takes a Long id instead. Likewise if it is known in advance that the expression is a leaf node built on an indexed attribute then the overload with the Long id argument is also preferrable unless an IndexEntry already exists in which case it makes no difference. The overload taking the ServerEntry itself is a last resort option and ok to use when it is known that no index exists for the attributes of Evaluators based on leaf expressions.

Author:

Apache Directory Project

Method Summary

Methods

Modifier and Type	Method and Description
boolean	evaluate(org.apache.directory.api.ldap.model.entry.Entry entry) Evaluates whether or not a candidate, satisfies the expression associated with this Evaluator .
boolean	evaluate(IndexEntry<?,String> entry) Evaluates a candidate to determine if a filter expression selects it.
N	getExpression() Gets the expression used by this expression Evaluator.
String	toString(String tabs) Pretty-print an Evaluator

Method Detail

evaluate

boolean evaluate(IndexEntry<?,String> entry)
                 throws org.apache.directory.api.ldap.model.exception.LdapException

Evaluates a candidate to determine if a filter expression selects it. If an IndexEntry does has a null reference to the entry object, this Evaluator may set it if it has to access the full entry within the master table of the store. Subsequent evaluations on the IndexEntry then need not access the store to retreive the entry if they need to access it's attributes.

Parameters:

entry - the index record of the entry to evaluate

Returns:

true if filter selects the candidate false otherwise

Throws:

Exception - if there are faults during evaluation

org.apache.directory.api.ldap.model.exception.LdapException

evaluate

boolean evaluate(org.apache.directory.api.ldap.model.entry.Entry entry)
                 throws Exception

Evaluates whether or not a candidate, satisfies the expression associated with this Evaluator .

Parameters:

entry - the candidate entry

Returns:

true if filter selects the candidate false otherwise

Throws:

Exception - if there are faults during evaluation

getExpression

N getExpression()

Gets the expression used by this expression Evaluator.

Returns:

the AST for the expression

toString

String toString(String tabs)

Pretty-print an Evaluator

Parameters:

tabs - The tabs to add before the evaluator

Returns:

The pretty-printed evaluator and its descendants