com.dbxml.db.core.query
Class QueryEngine

java.lang.Object
  com.dbxml.util.SimpleConfigurable
      com.dbxml.db.core.query.QueryEngine

All Implemented Interfaces:

Configurable

public class QueryEngine

extends SimpleConfigurable

QueryEngine is the dbXML Query Engine. Its purpose is to orchestrate query operations against the dbXML repository. The QueryEngine basically just manages a set of QueryResolvers that actually perform the work.

Constructor Summary

QueryEngine(Database db)

Method Summary

static Key[]	andKeySets(Key[][] keySets) andKeySets takes several sets of unique Keys and returns the ANDed set (elements that exist in all sets).
Query	compileQuery(Collection col, java.lang.String style, java.lang.String query, NamespaceMap nsMap, Key[] keys) compileQuery compiles a Query against the specified Collection context and returns the compiled Query.
static java.lang.String	expandEntities(java.lang.String value) expandEntities expands the String's pre-defined XML entities (<, >, etc...) into their actual character representations.
Database	getDatabase()
static Key[]	getUniqueKeys(IndexMatch[] matches) getUniqueKeys takes a set of IndexMatch objects and extracts all of its unique Keys in sorted order.
java.lang.String[]	listStyles() listStyles returns a list of styles supported by the QueryEngine (ex: XPath, XUpdate)
static java.lang.String	normalizeString(java.lang.String value) normalizeString normalizes the specific String by stripping all leading, trailing, and continuous runs of white space.
static Key[]	orKeySets(Key[][] keySets) orKeySets takes several sets of unique Keys and returns the ORed set (all unique elements).
ResultSet	query(Transaction tx, Collection col, java.lang.String style, java.lang.String query, NamespaceMap nsMap, Key[] keys) query performs the specified query and returns a NodeSet with any possible results from that query.
void	setConfig(Configuration config) setConfig sets the configuration information for the Configurable object instance.

Methods inherited from class com.dbxml.util.SimpleConfigurable

getConfig

Methods inherited from class java.lang.Object

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

Constructor Detail

QueryEngine

public QueryEngine(Database db)

Method Detail

setConfig

public void setConfig(Configuration config)
               throws dbXMLException

Description copied from interface: Configurable

setConfig sets the configuration information for the Configurable object instance.

Specified by:

setConfig in interface Configurable

Overrides:

setConfig in class SimpleConfigurable

Throws:

dbXMLException

getDatabase

public Database getDatabase()

listStyles

public java.lang.String[] listStyles()

listStyles returns a list of styles supported by the QueryEngine (ex: XPath, XUpdate)

Returns:

The supported styles

query

public ResultSet query(Transaction tx,
                       Collection col,
                       java.lang.String style,
                       java.lang.String query,
                       NamespaceMap nsMap,
                       Key[] keys)
                throws DBException,
                       QueryException

query performs the specified query and returns a NodeSet with any possible results from that query. The query is performed in the context of a Collection.

Parameters:

tx - The controlling Transaction

col - The Collection context

style - The query style (XPath, Fulltext, etc...)

query - The Query

nsMap - The namespace Map (if any)

keys - The initial Key set to use (if any)

Returns:

A ResultSet with the query results

Throws:

DBException

QueryException

compileQuery

public Query compileQuery(Collection col,
                          java.lang.String style,
                          java.lang.String query,
                          NamespaceMap nsMap,
                          Key[] keys)
                   throws DBException,
                          QueryException

compileQuery compiles a Query against the specified Collection context and returns the compiled Query. This DOES NOT actually run the query, merely just parses it and primes any possible Indexers that the query might need.

Parameters:

col - The Collection context

style - The query style (XPath, Fulltext, etc...)

query - The Query

nsMap - The namespace Map (if any)

keys - The initial Key set to use (if any)

Returns:

The compiled Query

Throws:

DBException

QueryException

getUniqueKeys

public static Key[] getUniqueKeys(IndexMatch[] matches)

getUniqueKeys takes a set of IndexMatch objects and extracts all of its unique Keys in sorted order.

Parameters:

matches - The Match Set

Returns:

The unique Keys in order

andKeySets

public static Key[] andKeySets(Key[][] keySets)

andKeySets takes several sets of unique Keys and returns the ANDed set (elements that exist in all sets). The first dimension of the array holds the individual sets, the second holds the actual Keys.

Parameters:

keySets - 2-dimensional set of Keys

Returns:

The ANDed set of Keys in order

orKeySets

public static Key[] orKeySets(Key[][] keySets)

orKeySets takes several sets of unique Keys and returns the ORed set (all unique elements). The first dimension of the array holds the individual sets, the second holds the actual Keys.

Parameters:

keySets - 2-dimensional set of Keys

Returns:

The ORed set of Keys in order

normalizeString

public static java.lang.String normalizeString(java.lang.String value)

normalizeString normalizes the specific String by stripping all leading, trailing, and continuous runs of white space.

Parameters:

value - The value to normalize

Returns:

The result

expandEntities

public static java.lang.String expandEntities(java.lang.String value)

expandEntities expands the String's pre-defined XML entities (<, >, etc...) into their actual character representations.

Parameters:

value - The value to expand entities for

Returns:

The expanded String