Package 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 2005-22, BSD License, Christian Gruen

Field Summary

Fields

Modifier and Type	Field	Description
TokenObjMap<Collation>	collations	Available collations.
Context	context	Database context.
ContextScope	contextScope	Context scope.
boolean	finalContext	Indicates if context scope exists and is final.
QueryFocus	focus	Current query focus.
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	functions	Functions.
QueryInfo	info	Query info.
LockList	locks	User-defined locks.
MainModule	main	Main module (root expression).
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.
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	Description
QueryContext(Context context)	Constructor.
QueryContext(Context context, QueryContext parent, QueryResources resources, QueryInfo info)	Constructor.
QueryContext(QueryContext parent)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	addLocks()	Collects lock strings (databases, special identifiers) when registering a query.
void	assign(StaticFunc func, Expr... args)	Creates a function call for the specified function and assigns it as root expression.
void	bind(String name, Object value, String type, StaticContext sc)	Binds a value to a global variable or the context value.
void	close()
void	compile()	Compiles the expression.
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.
Iter	iter()	Returns a result iterator.
Item	next(Iter iter)	Checks if evaluation has been stopped and returns the next item of an iterator.
void	optimize()	Optimizes the expression.
SerializerOptions	parameters()	Returns query-specific or default serialization parameters.
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 and assigns the root expression.
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.
void	set(Var var, Value value)	Binds an expression to a local variable.
String	shortInfo()	Returns short progress information.
StringList	suggest(String query, Data data)	Collects suggestions for completing a path expression.
String	toString()
FElem	toXml(boolean full)	Creates and returns an XML query plan (expression tree) for this query.
Updates	updates()	Returns 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.

functions

public final StaticFuncs functions

Functions.

resources

public final QueryResources resources

Query resources.

parent

public final QueryContext parent

Parent query context.

context

public final Context context

Database context.

info

public final QueryInfo info

Query info.

threads

public final QueryThreads threads

Query threads.

locks

public final LockList locks

User-defined locks.

focus

public QueryFocus focus

Current query focus.

updates

public Updates updates

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

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.

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.

main

public MainModule main

Main module (root expression).

contextScope

public ContextScope contextScope

Context scope.

finalContext

public boolean finalContext

Indicates if context scope exists and is final.

Constructor Detail

QueryContext

public QueryContext(QueryContext parent)

Constructor.

Parameters:

parent - parent context

QueryContext

public QueryContext(Context context)

Constructor.

Parameters:

context - database context

QueryContext

public QueryContext(Context context,
                    QueryContext parent,
                    QueryResources resources,
                    QueryInfo info)

Constructor.

Parameters:

context - database context

parent - parent context (can be null)

info - query info (can be null)

resources - resources (can be null)

Method Detail

parse

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

Parses the specified query.

Parameters:

query - query string

uri - base URI (can be null)

Returns:

module

Throws:

QueryException - query exception

suggest

public StringList suggest(String query,
                          Data data)

Collects suggestions for completing a path expression.

Parameters:

query - query string

data - data reference

Returns:

list of suggestions, followed by valid input string

parseMain

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

Parses the specified query.

Parameters:

query - query string

uri - base URI (can 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 and assigns the root expression.

Parameters:

query - query string

uri - base URI (can be null)

sc - static context (can 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 (can be null)

Returns:

library module

Throws:

QueryException - query exception

assign

public void assign(StaticFunc func,
                   Expr... args)
            throws QueryException

Creates a function call for the specified function and assigns it as root expression.

Parameters:

func - user-defined function

args - arguments

Throws:

QueryException - query exception

compile

public void compile()
             throws QueryException

Compiles the expression. Performs static optimizations.

Throws:

QueryException - query exception

optimize

public void optimize()
              throws QueryException

Optimizes the expression. Performs dynamic optimizations.

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 the updates container.

Returns:

updates container

addLocks

public void addLocks()

Description copied from class: Job

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

Overrides:

addLocks in class Job

bind

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

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)

sc - static context

Throws:

QueryException - query exception

evalInfo

public void evalInfo(String string)

Adds some evaluation info.

Parameters:

string - evaluation info

parameters

public SerializerOptions parameters()

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

toXml

public FElem toXml(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 AutoCloseable

Specified by:

close in interface Closeable

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