org.apache.tinkerpop.gremlin.jsr223

Class DefaultGremlinScriptEngineManager

java.lang.Object

org.apache.tinkerpop.gremlin.jsr223.DefaultGremlinScriptEngineManager

All Implemented Interfaces:

GremlinScriptEngineManager

Direct Known Subclasses:

CachedGremlinScriptEngineManager

public class DefaultGremlinScriptEngineManager
extends Object
implements GremlinScriptEngineManager

The ScriptEngineManager implements a discovery, instantiation and configuration mechanism for GremlinScriptEngine classes and also maintains a collection of key/value pairs storing state shared by all engines created by it. This class uses the ServiceProvider mechanism to enumerate all the implementations of GremlinScriptEngineFactory. The ScriptEngineManager provides a method to return a list of all these factories as well as utility methods which look up factories on the basis of language name, file extension and mime type.

The Bindings of key/value pairs, referred to as the "Global Scope" maintained by the manager is available to all instances of @code ScriptEngine} created by the GremlinScriptEngineManager. The values in the Bindings are generally exposed in all scripts.

This class is based quite heavily on the workings of the ScriptEngineManager supplied in the javax.script packages, but adds some additional features that are specific to Gremlin and TinkerPop. Unfortunately, it's not easily possible to extend ScriptEngineManager directly as there certain behaviors don't appear to be be straightforward to implement and member variables are all private. It is important to note that this class is designed to provide support for "Gremlin-enabled" ScriptEngine instances (i.e. those that extend from GremlinScriptEngine) and is not meant to manage just any ScriptEngine instance that may be on the path.

As this is a "Gremlin" ScriptEngine, certain common imports are automatically applied when a GremlinScriptEngine is instantiated via the GremlinScriptEngineFactory.. Initial imports from gremlin-core come from the CoreImports.

Author:

Stephen Mallette (http://stephen.genoprime.com)

Constructor Summary

Constructors

Constructor and Description
DefaultGremlinScriptEngineManager() The effect of calling this constructor is the same as calling DefaultGremlinScriptEngineManager(Thread.currentThread().getContextClassLoader()).
DefaultGremlinScriptEngineManager(ClassLoader loader) This constructor loads the implementations of GremlinScriptEngineFactory visible to the given ClassLoader using the ServiceLoader mechanism.

Method Summary

Modifier and Type	Method and Description
void	addPlugin(GremlinPlugin plugin) Add GremlinPlugin instances to customize newly created GremlinScriptEngine instances.
Object	get(String key) Gets the value for the specified key in the global scope.
Bindings	getBindings() Gets the bindings of the Bindings in global scope.
List<Customizer>	getCustomizers(String scriptEngineName) Get the list of Customizer instances filtered by the scriptEngineName.
GremlinScriptEngine	getEngineByExtension(String extension) Look up and create a GremlinScriptEngine for a given extension.
GremlinScriptEngine	getEngineByMimeType(String mimeType) Look up and create a GremlinScriptEngine for a given mime type.
GremlinScriptEngine	getEngineByName(String shortName) Looks up and creates a GremlinScriptEngine for a given name.
List<GremlinScriptEngineFactory>	getEngineFactories() Returns a list whose elements are instances of all the GremlinScriptEngineFactory classes found by the discovery mechanism.
void	put(String key, Object value) Sets the specified key/value pair in the global scope.
void	registerEngineExtension(String extension, GremlinScriptEngineFactory factory) Registers a GremlinScriptEngineFactory to handle an extension.
void	registerEngineMimeType(String type, GremlinScriptEngineFactory factory) Registers a GremlinScriptEngineFactory to handle a mime type.
void	registerEngineName(String name, GremlinScriptEngineFactory factory) Registers a GremlinScriptEngineFactory to handle a language name.
void	setBindings(Bindings bindings) Stores the specified Bindings as a global for all GremlinScriptEngine objects created by it.

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultGremlinScriptEngineManager

public DefaultGremlinScriptEngineManager()

The effect of calling this constructor is the same as calling DefaultGremlinScriptEngineManager(Thread.currentThread().getContextClassLoader()).

DefaultGremlinScriptEngineManager

public DefaultGremlinScriptEngineManager(ClassLoader loader)

This constructor loads the implementations of GremlinScriptEngineFactory visible to the given ClassLoader using the ServiceLoader mechanism. If loader is null, the script engine factories that are bundled with the platform and that are in the usual extension directories (installed extensions) are loaded.

Method Detail

getCustomizers

public List<Customizer> getCustomizers(String scriptEngineName)

Description copied from interface: GremlinScriptEngineManager

Get the list of Customizer instances filtered by the scriptEngineName.

Specified by:

getCustomizers in interface GremlinScriptEngineManager

addPlugin

public void addPlugin(GremlinPlugin plugin)

Description copied from interface: GremlinScriptEngineManager

Add GremlinPlugin instances to customize newly created GremlinScriptEngine instances.

Specified by:

addPlugin in interface GremlinScriptEngineManager

setBindings

public void setBindings(Bindings bindings)

Stores the specified Bindings as a global for all GremlinScriptEngine objects created by it. If the bindings are to be updated by multiple threads it is recommended that a ConcurrentBindings instance is supplied.

Specified by:

setBindings in interface GremlinScriptEngineManager

Throws:

IllegalArgumentException - if bindings is null.

getBindings

public Bindings getBindings()

Gets the bindings of the Bindings in global scope.

Specified by:

getBindings in interface GremlinScriptEngineManager

put

public void put(String key,
                Object value)

Sets the specified key/value pair in the global scope. The key may not be null or empty.

Specified by:

put in interface GremlinScriptEngineManager

Throws:

IllegalArgumentException - if key is null or empty.

get

public Object get(String key)

Gets the value for the specified key in the global scope.

Specified by:

get in interface GremlinScriptEngineManager

getEngineByName

public GremlinScriptEngine getEngineByName(String shortName)

Looks up and creates a GremlinScriptEngine for a given name. The algorithm first searches for a GremlinScriptEngineFactory that has been registered as a handler for the specified name using the registerEngineExtension(String, GremlinScriptEngineFactory) method. If one is not found, it searches the set of GremlinScriptEngineFactory instances stored by the constructor for one with the specified name. If a ScriptEngineFactory is found by either method, it is used to create instance of GremlinScriptEngine.

Specified by:

getEngineByName in interface GremlinScriptEngineManager

Parameters:

shortName - The short name of the GremlinScriptEngine implementation returned by the ScriptEngineFactory.getNames() method.

Returns:

A GremlinScriptEngine created by the factory located in the search. Returns null if no such factory was found. The global scope of this manager is applied to the newly created GremlinScriptEngine

Throws:

NullPointerException - if shortName is null.

getEngineByExtension

public GremlinScriptEngine getEngineByExtension(String extension)

Look up and create a GremlinScriptEngine for a given extension. The algorithm used by getEngineByName(String) is used except that the search starts by looking for a GremlinScriptEngineFactory registered to handle the given extension using registerEngineExtension(String, GremlinScriptEngineFactory).

Specified by:

getEngineByExtension in interface GremlinScriptEngineManager

Returns:

The engine to handle scripts with this extension. Returns null if not found.

Throws:

NullPointerException - if extension is null.

getEngineByMimeType

public GremlinScriptEngine getEngineByMimeType(String mimeType)

Look up and create a GremlinScriptEngine for a given mime type. The algorithm used by getEngineByName(String) is used except that the search starts by looking for a GremlinScriptEngineFactory registered to handle the given mime type using registerEngineMimeType(String, GremlinScriptEngineFactory).

Specified by:

getEngineByMimeType in interface GremlinScriptEngineManager

Parameters:

mimeType - The given mime type

Returns:

The engine to handle scripts with this mime type. Returns null if not found.

Throws:

NullPointerException - if mime-type is null.

getEngineFactories

public List<GremlinScriptEngineFactory> getEngineFactories()

Returns a list whose elements are instances of all the GremlinScriptEngineFactory classes found by the discovery mechanism.

Specified by:

getEngineFactories in interface GremlinScriptEngineManager

Returns:

List of all discovered GremlinScriptEngineFactory objects.

registerEngineName

public void registerEngineName(String name,
                               GremlinScriptEngineFactory factory)

Registers a GremlinScriptEngineFactory to handle a language name. Overrides any such association found using the discovery mechanism.

Specified by:

registerEngineName in interface GremlinScriptEngineManager

Parameters:

name - The name to be associated with the GremlinScriptEngineFactory

factory - The class to associate with the given name.

Throws:

NullPointerException - if any of the parameters is null.

registerEngineMimeType

public void registerEngineMimeType(String type,
                                   GremlinScriptEngineFactory factory)

Registers a GremlinScriptEngineFactory to handle a mime type. Overrides any such association found using the discovery mechanism.

Specified by:

registerEngineMimeType in interface GremlinScriptEngineManager

Parameters:

type - The mime type to be associated with the GremlinScriptEngineFactory.

factory - The class to associate with the given mime type.

Throws:

NullPointerException - if any of the parameters is null.

registerEngineExtension

public void registerEngineExtension(String extension,
                                    GremlinScriptEngineFactory factory)

Registers a GremlinScriptEngineFactory to handle an extension. Overrides any such association found using the discovery mechanism.

Specified by:

registerEngineExtension in interface GremlinScriptEngineManager

Parameters:

extension - The extension type to be associated with the GremlinScriptEngineFactory

factory - The class to associate with the given extension.

Throws:

NullPointerException - if any of the parameters is null.