org.basex.query

Class QueryContext

java.lang.Object

org.basex.core.jobs.Job

org.basex.query.QueryContext

All Implemented Interfaces:

Closeable, AutoCloseable

public final class QueryContext
extends Job
implements Closeable

This class organizes both static and dynamic properties that are specific to a single query.

Author:

BaseX Team 2005-21, BSD License, Christian Gruen

Field Summary

Fields

Modifier and Type	Field and Description
TokenObjMap<Collation>	collations Available collations.
Context	context Database context.
MainModule	ctxItem Initial context value.
QueryDateTime	dateTime Current date/time values.
QueryFocus	focus Current context value.
FTLexer	ftLexer Current full-text lexer.
int	ftPos Full-text token positions (needed for highlighting full-text results).
FTPosData	ftPosData Full-text position data (needed for highlighting full-text results).
StaticFuncs	funcs Functions.
QueryInfo	info Query info.
LockList	locks User-defined locks.
int	maxCalls Maximum number of successive tail calls (will be set before compilation).
TokenMap	modParsed Parsed modules, containing the file path and module uri.
QueryContext	parent Parent query context.
QueryResources	resources Query resources.
MainModule	root Root expression of the query.
boolean	scoring Scoring flag.
QueryStack	stack The evaluation stack.
int	tailCalls Number of successive tail calls.
QueryThreads	threads Query threads.
Updates	updates Update container; will be created if the first update is evaluated.
int	varIDs Counter for variable IDs.
Variables	vars Static variables.

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

state, updating

Constructor Summary

Constructors

Constructor and Description
QueryContext(Context context) Constructor.
QueryContext(QueryContext parent) Constructor.

Method Summary

Modifier and Type	Method and Description
void	addLocks() Adds the strings (databases, special identifiers) for which locks need to be acquired.
void	bind(QNm name, Value value) Binds a value to a global variable.
void	bind(String name, Object value, String type, StaticContext sc) Binds a value to a global variable.
void	bind(String name, Value value, StaticContext sc) Binds a value to a global variable.
void	close()
void	compile() Compiles and optimizes the expression.
void	context(Object value, String type, StaticContext sc) Binds the context value, using the same rules as for binding variables.
void	context(Value value, StaticContext sc) Binds the context value.
QueryDateTime	dateTime() Initializes the static date and time context of a query if not done yet.
void	evalInfo(String string) Adds some evaluation info.
FTOpt	ftOpt() Returns the current full-text options.
void	ftOpt(FTOpt opt) Assigns full-text options.
Value	get(Var var) Gets the value currently bound to the given variable.
String	info() Returns info on query compilation and evaluation.
Iter	iter() Returns a result iterator.
void	mainModule(MainModule rt) Sets the main module (root expression).
Item	next(Iter iter) Checks if evaluation has been stopped and returns the next item of an iterator.
AModule	parse(String query, boolean library, String uri) Parses the specified query.
AModule	parse(String query, String uri) Parses the specified query.
LibraryModule	parseLibrary(String query, String uri) Parses the specified module.
MainModule	parseMain(String query, String uri) Parses the specified query.
MainModule	parseMain(String query, String uri, StaticContext sc) Parses the specified query.
FElem	plan(boolean full) Creates and returns an XML query plan (expression tree) for this query.
Value[]	pollTailArgs() Returns and clears registered arguments of a tail-called function.
XQFunction	pollTailCall() Returns and clears the currently registered tail-call function.
void	registerTailCall(XQFunction fn, Value[] arg) Registers a tail-called function and its arguments to this query context.
SerializerOptions	serParams() Returns query-specific or default serialization parameters.
void	set(Var var, Value value) Binds an expression to a local variable.
String	shortInfo() Returns short progress information.
String	toString()
Updates	updates() Returns a reference to the updates container.
void	updating() Indicates that the query contains updating expressions.
Value	value() Returns the result.

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

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

Methods inherited from class java.lang.Object

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

Field Detail

stack

public final QueryStack stack

The evaluation stack.

vars

public final Variables vars

Static variables.

funcs

public final StaticFuncs funcs

Functions.

parent

public final QueryContext parent

Parent query context.

info

public final QueryInfo info

Query info.

context

public final Context context

Database context.

resources

public QueryResources resources

Query resources.

updates

public Updates updates

Update container; will be created if the first update is evaluated.

threads

public final QueryThreads threads

Query threads.

focus

public QueryFocus focus

Current context value.

dateTime

public QueryDateTime dateTime

Current date/time values.

ftPosData

public FTPosData ftPosData

Full-text position data (needed for highlighting full-text results).

ftLexer

public FTLexer ftLexer

Current full-text lexer.

ftPos

public int ftPos

Full-text token positions (needed for highlighting full-text results).

scoring

public boolean scoring

Scoring flag.

collations

public TokenObjMap<Collation> collations

Available collations.

locks

public final LockList locks

User-defined locks.

tailCalls

public int tailCalls

Number of successive tail calls.

maxCalls

public int maxCalls

Maximum number of successive tail calls (will be set before compilation).

varIDs

public int varIDs

Counter for variable IDs.

modParsed

public final TokenMap modParsed

Parsed modules, containing the file path and module uri.

ctxItem

public MainModule ctxItem

Initial context value.

root

public MainModule root

Root expression of the query.

Constructor Detail

QueryContext

public QueryContext(QueryContext parent)

Constructor.

Parameters:

parent - parent context

QueryContext

public QueryContext(Context context)

Constructor.

Parameters:

context - database context

Method Detail

parse

public AModule parse(String query,
                     String uri)
              throws QueryException

Parses the specified query.

Parameters:

query - query string

uri - base URI (may be null)

Returns:

main module

Throws:

QueryException - query exception

parse

public AModule parse(String query,
                     boolean library,
                     String uri)
              throws QueryException

Parses the specified query.

Parameters:

query - query string

library - library/main module

uri - base URI (may be null)

Returns:

main module

Throws:

QueryException - query exception

parseMain

public MainModule parseMain(String query,
                            String uri)
                     throws QueryException

Parses the specified query.

Parameters:

query - query string

uri - base URI (may be null)

Returns:

main module

Throws:

QueryException - query exception

parseMain

public MainModule parseMain(String query,
                            String uri,
                            StaticContext sc)
                     throws QueryException

Parses the specified query.

Parameters:

query - query string

uri - base URI (may be null)

sc - static context (may be null)

Returns:

main module

Throws:

QueryException - query exception

parseLibrary

public LibraryModule parseLibrary(String query,
                                  String uri)
                           throws QueryException

Parses the specified module.

Parameters:

query - query string

uri - base URI (may be null)

Returns:

name of module

Throws:

QueryException - query exception

mainModule

public void mainModule(MainModule rt)

Sets the main module (root expression).

Parameters:

rt - main module

compile

public void compile()
             throws QueryException

Compiles and optimizes the expression.

Throws:

QueryException - query exception

iter

public Iter iter()
          throws QueryException

Returns a result iterator.

Returns:

result iterator

Throws:

QueryException - query exception

value

public Value value()
            throws QueryException

Returns the result.

Returns:

result iterator

Throws:

QueryException - query exception

next

public Item next(Iter iter)
          throws QueryException

Checks if evaluation has been stopped and returns the next item of an iterator.

Parameters:

iter - iterator

Returns:

item or null

Throws:

QueryException - query exception

updates

public Updates updates()

Returns a reference to the updates container.

Returns:

updates container

addLocks

public void addLocks()

Description copied from class: Job

Adds the strings (databases, special identifiers) for which locks need to be acquired.

Overrides:

addLocks in class Job

context

public void context(Object value,
                    String type,
                    StaticContext sc)
             throws QueryException

Binds the context value, using the same rules as for binding variables.

Parameters:

value - value to be bound

type - type (may be null)

sc - static context

Throws:

QueryException - query exception

context

public void context(Value value,
                    StaticContext sc)

Binds the context value.

Parameters:

value - value to be bound

sc - static context

bind

public void bind(String name,
                 Object value,
                 String type,
                 StaticContext sc)
          throws QueryException

Binds a value to a global variable. The specified type is interpreted as follows:

• If "json" is specified, the value is converted according to the rules specified in JsonXQueryConverter.
• Otherwise, the type is cast to the specified XDM type.

If the value is an XQuery Value, it is directly assigned. Otherwise, it is cast to the XQuery data model, using a Java/XQuery mapping.

Parameters:

name - name of variable

value - value to be bound

type - type (may be null)

sc - static context

Throws:

QueryException - query exception

bind

public void bind(String name,
                 Value value,
                 StaticContext sc)
          throws QueryException

Binds a value to a global variable.

Parameters:

name - name of variable

value - value to be bound

sc - static context

Throws:

QueryException - query exception

bind

public void bind(QNm name,
                 Value value)

Binds a value to a global variable.

Parameters:

name - name of variable

value - value to be bound

evalInfo

public void evalInfo(String string)

Adds some evaluation info.

Parameters:

string - evaluation info

info

public String info()

Returns info on query compilation and evaluation.

Returns:

query info

serParams

public SerializerOptions serParams()

Returns query-specific or default serialization parameters.

Returns:

serialization parameters

ftOpt

public FTOpt ftOpt()

Returns the current full-text options. Creates a new instance if called for the first time.

Returns:

full-text options

ftOpt

public void ftOpt(FTOpt opt)

Assigns full-text options.

Parameters:

opt - full-text options

plan

public FElem plan(boolean full)

Creates and returns an XML query plan (expression tree) for this query.

Parameters:

full - include comprehensive information

Returns:

query plan

updating

public void updating()

Indicates that the query contains updating expressions.

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

shortInfo

public String shortInfo()

Description copied from class: Job

Returns short progress information. Can be overwritten to give more specific feedback.

Overrides:

shortInfo in class Job

Returns:

header information

get

public Value get(Var var)

Gets the value currently bound to the given variable.

Parameters:

var - variable

Returns:

bound value

set

public void set(Var var,
                Value value)
         throws QueryException

Binds an expression to a local variable.

Parameters:

var - variable

value - expression to be bound

Throws:

QueryException - exception

registerTailCall

public void registerTailCall(XQFunction fn,
                             Value[] arg)

Registers a tail-called function and its arguments to this query context.

Parameters:

fn - function to call

arg - arguments to pass to fn

pollTailCall

public XQFunction pollTailCall()

Returns and clears the currently registered tail-call function.

Returns:

function to call if present, null otherwise

pollTailArgs

public Value[] pollTailArgs()

Returns and clears registered arguments of a tail-called function.

Returns:

argument values if a tail call was registered, null otherwise

dateTime

public QueryDateTime dateTime()
                       throws QueryException

Initializes the static date and time context of a query if not done yet.

Returns:

self reference

Throws:

QueryException - query exception

toString

public String toString()

Overrides:

toString in class Object