Package org.basex.query

Class QueryProcessor

java.lang.Object

org.basex.core.jobs.Job

org.basex.query.QueryProcessor

All Implemented Interfaces:

Closeable, AutoCloseable

public final class QueryProcessor
extends Job
implements Closeable

This class is an entry point for evaluating XQuery strings.

Author:

BaseX Team 2005-22, BSD License, Christian Gruen

Field Summary

Fields

Modifier and Type	Field	Description
QueryContext	qc	Expression context.
StaticContext	sc	Static context.

Fields inherited from class org.basex.core.jobs.Job

state, updating

Constructor Summary

Constructors

Constructor	Description
QueryProcessor(String query, String uri, Context ctx, QueryInfo info)	Default constructor.
QueryProcessor(String query, Context ctx)	Default constructor.

Method Summary

Modifier and Type	Method	Description
void	addLocks()	Collects lock strings (databases, special identifiers) when registering a query.
void	cache(AQuery cmd, int max)	This function is called by the GUI.
void	close()
void	compile()	Compiles the query.
QueryProcessor	context(Object value)	Binds the context value.
QueryProcessor	context(Object value, String type)	Binds the context value with a specified type, using the same rules as for binding variables.
Iter	iter()	Returns a memory-efficient result iterator.
void	module(String uri, String file)	Adds a module reference.
QueryProcessor	namespace(String prefix, String uri)	Declares a namespace.
void	optimize()	Optimizes the query.
void	parse()	Parses the query.
Serializer	serializer(OutputStream os)	Returns a serializer for the given output stream.
String	toString()
FElem	toXml()	Returns a query plan as XML.
int	updates()	Returns the number of performed updates after query execution, or 0.
QueryProcessor	uriResolver(UriResolver resolver)	Assigns a URI resolver.
Value	value()	Evaluates the query and returns the resulting value.
QueryProcessor	variable(String name, Object value)	Binds a value to a global variable.
QueryProcessor	variable(String name, Object value, String type)	Binds a value to a global variable or the context value.

Methods inherited from class org.basex.core.jobs.Job

active, checkStop, detailedInfo, jc, memory, popJob, progressInfo, pushJob, register, shortInfo, state, stop, stopped, timeout, unregister

Methods inherited from class java.lang.Object

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

Field Detail

sc

public final StaticContext sc

Static context.

qc

public final QueryContext qc

Expression context.

Constructor Detail

QueryProcessor

public QueryProcessor(String query,
                      Context ctx)

Default constructor.

Parameters:

query - query string

ctx - database context

QueryProcessor

public QueryProcessor(String query,
                      String uri,
                      Context ctx,
                      QueryInfo info)

Default constructor.

Parameters:

query - query string

uri - base uri (can be null)

ctx - database context

info - query info (can be null)

Method Detail

parse

public void parse()
           throws QueryException

Parses the query.

Throws:

QueryException - query exception

compile

public void compile()
             throws QueryException

Compiles the query.

Throws:

QueryException - query exception

optimize

public void optimize()
              throws QueryException

Optimizes the query.

Throws:

QueryException - query exception

iter

public Iter iter()
          throws QueryException

Returns a memory-efficient result iterator. The query will only be fully evaluated if all items of this iterator are requested.

Returns:

result iterator

Throws:

QueryException - query exception

value

public Value value()
            throws QueryException

Evaluates the query and returns the resulting value.

Returns:

result value

Throws:

QueryException - query exception

cache

public void cache(AQuery cmd,
                  int max)
           throws QueryException

This function is called by the GUI. Caches the result of the specified query. If all nodes are of the same database instance, the cached value will be of type DBNodes.

Parameters:

cmd - query command

max - maximum number of items to cache (negative: return full result)

Throws:

QueryException - query exception

variable

public QueryProcessor variable(String name,
                               Object value,
                               String type)
                        throws QueryException

Binds a value to a global variable or the context value. The arguments will be ignored if a value has already been assigned.

Parameters:

name - name of variable; context value if empty string or null

value - value to be bound (object or XQuery Value)

type - type (may be null)

Returns:

self reference

Throws:

QueryException - query exception

See Also:

QueryContext.bind(String, Object, String, StaticContext)

variable

public QueryProcessor variable(String name,
                               Object value)
                        throws QueryException

Binds a value to a global variable.

Parameters:

name - name of variable

value - value to be bound

Returns:

self reference

Throws:

QueryException - query exception

context

public QueryProcessor context(Object value)
                       throws QueryException

Binds the context value.

Parameters:

value - value to be bound

Returns:

self reference

Throws:

QueryException - query exception

context

public QueryProcessor context(Object value,
                              String type)
                       throws QueryException

Binds the context value with a specified type, using the same rules as for binding variables.

Parameters:

value - value to be bound

type - type (may be null)

Returns:

self reference

Throws:

QueryException - query exception

namespace

public QueryProcessor namespace(String prefix,
                                String uri)
                         throws QueryException

Declares a namespace. A namespace is undeclared if the uri is an empty string. The default element namespaces is set if the prefix is empty.

Parameters:

prefix - namespace prefix

uri - namespace uri

Returns:

self reference

Throws:

QueryException - query exception

uriResolver

public QueryProcessor uriResolver(UriResolver resolver)

Assigns a URI resolver.

Parameters:

resolver - resolver

Returns:

self reference

serializer

public Serializer serializer(OutputStream os)
                      throws IOException,
                             QueryException

Returns a serializer for the given output stream. Optional output declarations within the query will be included in the serializer instance.

Parameters:

os - output stream

Returns:

serializer instance

Throws:

IOException - query exception

QueryException - query exception

module

public void module(String uri,
                   String file)

Adds a module reference. Only called from the test APIs.

Parameters:

uri - module uri

file - file name

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

addLocks

public void addLocks()

Description copied from class: Job

Collects lock strings (databases, special identifiers) when registering a query.

Overrides:

addLocks in class Job

updates

public int updates()

Returns the number of performed updates after query execution, or 0.

Returns:

number of updates

toXml

public FElem toXml()

Returns a query plan as XML.

Returns:

query plan

toString

public String toString()

Overrides:

toString in class Object