org.basex.core

Class Command

java.lang.Object

org.basex.core.Progress

org.basex.core.Command

Direct Known Subclasses:

ACreate, AlterUser, Check, Close, Copy, CreateBackup, CreateEvent, CreateUser, Cs, DropBackup, DropEvent, DropUser, Exit, Export, Find, Flush, Get, Grant, Help, Info, InfoDB, InfoIndex, InfoStorage, Kill, List, ListDB, Open, Password, RepoDelete, RepoInstall, RepoList, Restore, Run, Set, ShowBackups, ShowDatabases, ShowEvents, ShowSessions, ShowUsers, XQuery

public abstract class Command
extends Progress

This class provides the architecture for all internal command implementations. It evaluates queries that are sent by the GUI, the client or the standalone version.

Author:

BaseX Team 2005-12, BSD License, Christian Gruen

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.String[]	args Command arguments.
protected Context	context Database context.
protected static int	DATAREF Commands flag: data reference needed.
protected org.xml.sax.InputSource	in Optional input source.
protected MainProp	mprop Main properties.
protected PrintOutput	out Output stream.
protected Performance	perf Performance measurements.
protected Prop	prop Database properties.
protected static int	STANDARD Commands flag: standard.

Fields inherited from class org.basex.core.Progress

updating

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Command(int flag, java.lang.String... arg) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	build(CommandBuilder cb) Builds a string representation from the command.
protected static boolean	close(Context ctx, java.lang.String db) Closes the specified database if it is currently opened and only pinned once.
protected boolean	error(java.lang.String msg, java.lang.Object... ext) Adds the error message to the message buffer info.
java.lang.String	execute(Context ctx) Executes the command and returns the result as string.
void	execute(Context ctx, java.io.OutputStream os) Executes the command and prints the result to the specified output stream.
protected <E extends java.lang.Enum<E>> E	getOption(java.lang.Class<E> typ) Returns the specified command option.
protected static <E extends java.lang.Enum<E>> E	getOption(java.lang.String s, java.lang.Class<E> typ) Returns the specified command option.
java.lang.String	info() Returns command information.
protected boolean	info(java.lang.String str, java.lang.Object... ext) Adds information on command execution.
boolean	newData(Context ctx) Closes an open data reference and returns true if this command will change the Context.data reference.
java.lang.String	pinned(Context ctx) Checks if the database to be updated is opened (pinned) by a process in another JVM.
Result	result() Returns the result set, generated by a query command.
protected abstract boolean	run() Executes the command and serializes the result (internal call).
boolean	run(Context ctx) Runs the command without permission, data and concurrency checks.
void	setInput(org.xml.sax.InputSource is) Attaches an input source.
void	setInput(java.io.InputStream is) Attaches an input stream.
boolean	stoppable() Returns true if this command can be stopped.
boolean	supportsProg() Returns true if this command returns a progress value.
java.lang.String	toString()
boolean	updated() Checks if the command has updated any data.
boolean	updating(Context ctx) Checks if the command performs updates/write operations.

Methods inherited from class org.basex.core.Progress

abort, checkStop, det, detail, prog, progress, progress, startTimeout, stop, stopTimeout, tit, title

Methods inherited from class java.lang.Object

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

Field Detail

STANDARD

protected static final int STANDARD

Commands flag: standard.

See Also:

Constant Field Values

DATAREF

protected static final int DATAREF

Commands flag: data reference needed.

See Also:

Constant Field Values

args

protected final java.lang.String[] args

Command arguments.

perf

protected Performance perf

Performance measurements.

context

protected Context context

Database context.

out

protected PrintOutput out

Output stream.

in

protected org.xml.sax.InputSource in

Optional input source.

prop

protected Prop prop

Database properties.

mprop

protected MainProp mprop

Main properties.

Constructor Detail

Command

protected Command(int flag,
       java.lang.String... arg)

Constructor.

Parameters:

flag - command flags

arg - arguments

Method Detail

execute

public final void execute(Context ctx,
           java.io.OutputStream os)
                   throws BaseXException

Executes the command and prints the result to the specified output stream. If an exception occurs, a BaseXException is thrown.

Parameters:

ctx - database context

os - output stream reference

Throws:

BaseXException - command exception

execute

public final java.lang.String execute(Context ctx)
                               throws BaseXException

Executes the command and returns the result as string. If an exception occurs, a BaseXException is thrown.

Parameters:

ctx - database context

Returns:

string result

Throws:

BaseXException - command exception

setInput

public void setInput(java.io.InputStream is)

Attaches an input stream.

Parameters:

is - input stream

setInput

public void setInput(org.xml.sax.InputSource is)

Attaches an input source.

Parameters:

is - input source

run

public final boolean run(Context ctx)

Runs the command without permission, data and concurrency checks. Should be called with care, and only by other database commands.

Parameters:

ctx - database context

Returns:

result of check

info

public final java.lang.String info()

Returns command information.

Returns:

info string

result

public Result result()

Returns the result set, generated by a query command. Will only yield results if Prop.CACHEQUERY is set, and can only be called once.

Returns:

result set

updating

public boolean updating(Context ctx)

Checks if the command performs updates/write operations.

Parameters:

ctx - database context

Returns:

result of check

pinned

public java.lang.String pinned(Context ctx)

Checks if the database to be updated is opened (pinned) by a process in another JVM.

Parameters:

ctx - database context

Returns:

name of pinned database

updated

public boolean updated()

Checks if the command has updated any data. If this method is called before command execution, it always returns true.

Returns:

result of check

newData

public boolean newData(Context ctx)

Closes an open data reference and returns true if this command will change the Context.data reference. This method is required by the progress dialog in the frontend.

Parameters:

ctx - database context

Returns:

result of check

supportsProg

public boolean supportsProg()

Returns true if this command returns a progress value. This method is required by the progress dialog in the frontend.

Returns:

result of check

stoppable

public boolean stoppable()

Returns true if this command can be stopped. This method is required by the progress dialog in the frontend.

Returns:

result of check

toString

public final java.lang.String toString()

Overrides:

toString in class java.lang.Object

run

protected abstract boolean run()
                        throws java.io.IOException

Executes the command and serializes the result (internal call).

Returns:

success of operation

Throws:

java.io.IOException - I/O exception

build

protected void build(CommandBuilder cb)

Builds a string representation from the command. This string must be correctly built, as commands are sent to the server as strings.

Parameters:

cb - command builder

error

protected final boolean error(java.lang.String msg,
            java.lang.Object... ext)

Adds the error message to the message buffer info.

Parameters:

msg - error message

ext - error extension

Returns:

false

info

protected final boolean info(java.lang.String str,
           java.lang.Object... ext)

Adds information on command execution.

Parameters:

str - information to be added

ext - extended info

Returns:

true

getOption

protected final <E extends java.lang.Enum<E>> E getOption(java.lang.Class<E> typ)

Returns the specified command option.

Type Parameters:

E - token type

Parameters:

typ - options enumeration

Returns:

option

getOption

protected static <E extends java.lang.Enum<E>> E getOption(java.lang.String s,
                                        java.lang.Class<E> typ)

Returns the specified command option.

Type Parameters:

E - token type

Parameters:

s - string to be found

typ - options enumeration

Returns:

option

close

protected static boolean close(Context ctx,
            java.lang.String db)

Closes the specified database if it is currently opened and only pinned once.

Parameters:

ctx - database context

db - database to be closed

Returns:

closed flag