package javax.script;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
/**
* ScriptEngineManager implements a discovery and instantiation
* mechanisams for ScriptEngine class. It also contains a collection
* of key-value pairs which storing state shared by all engines
* created by manager.
*
* Nandika Jayawardana <nandika@opensource.lk>
* Sanka Samaranayake <sanka@opensource.lk>
*/
public class ScriptEngineManager {
/** Stores all instances of classes which implements
* ScriptEngineFactory which are found in resources
* META-INF/services/javax.script.ScriptEngineFactory
*/
protected HashSet engineSpis = new HashSet();
/**
* Stores language names with an associated
* ScriptEngineFactory
*/
protected HashMap nameAssociations = new HashMap();
/**
* Stores file extensions with an associated
* ScriptEngineFactory
*/
protected HashMap extensionAssocitions = new HashMap();
/** Stores MIME types with an associated ScriptEngineFactory */
protected HashMap mimeTypeAssociations = new HashMap();
/** Stores the namespace associated with GLOBAL_SCOPE */
protected Bindings globalscope = new SimpleBindings();
private Iterator getServiceProviders() {
Iterator i = null;
try {
Class c = Class.forName("gnu.classpath.ServiceFactory");
Method m = c.getMethod("lookupProviders", new Class[]{java.lang.Class.class});
try {m.setAccessible(true);} catch (Throwable tt) {/*ignore*/}
i = (Iterator) m.invoke(c, new Class[]{ScriptEngineFactory.class});
} catch (Throwable ex) {/*ignore*/}
if(i!=null) return i;
try {
Class c = Class.forName("sun.misc.Service");
Method m = c.getMethod("providers", new Class[]{java.lang.Class.class});
try {m.setAccessible(true);} catch (Throwable tt) {/*ignore*/}
i = (Iterator) m.invoke(c, new Class[]{ScriptEngineFactory.class});
} catch (Throwable ex) {/*ignore*/}
return i;
}
/**
* Constructs ScriptEngineManager and initializes it.
*/
public ScriptEngineManager() {
Iterator iterator = getServiceProviders();
while (iterator.hasNext()) {
ScriptEngineFactory factory = (ScriptEngineFactory) iterator.next();
engineSpis.add(factory);
String[] data = (String[]) factory.getNames().toArray(new String[]{});
// gets all descriptinve names for Scripting Engine
for (int i=0; i<data.length; i++) {
nameAssociations.put(data[i], factory);
}
// gets all supported extensions
data = (String[]) factory.getExtensions().toArray(new String[]{});
for (int i=0; i<data.length; i++) {
extensionAssocitions.put(data[i], factory);
}
// gets all supported MIME types
data = (String[]) factory.getMimeTypes().toArray(new String[]{});
for (int i=0; i<data.length; i++) {
mimeTypeAssociations.put(data[i], factory);
}
}
}
/**
* Retrieves the associated value for the spefied key in the
* GLOBAL_SCOPE
*
* @param key the associated key of the value stored in the
* GLOBAL_SCOPE
* @return the value associated with the specifed key
*/
public Object get(String key){
return globalscope.get(key);
}
/**
* Retrieves a new instance of a ScriptingEngine for the
* specified extension of a scirpt file. Returns null if no
* suitable ScriptingEngine is found.
*
* @param extension the specified extension of a script file
* @return a new instance of a ScriptingEngine which supports the
* specified script file extension
*/
public ScriptEngine getEngineByExtention(String extension){
ScriptEngine engine = null;
ScriptEngineFactory factory =
(ScriptEngineFactory) extensionAssocitions.get(extension);
if (factory != null) {
// gets a new instance of the Scripting Engine
engine = factory.getScriptEngine();
// sets the GLOBAL SCOPE
engine.setBindings(globalscope,ScriptContext.GLOBAL_SCOPE);
}
return engine;
}
/**
* Retrieves new instance the ScriptingEngine for a specifed MIME
* type. Returns null if no suitable ScriptingEngine is found.
*
* @param mimeType the specified MIME type
* @return a new instance of a ScriptingEngine which supports the
* specified MIME type
*/
public ScriptEngine getEngineByMimeType(String mimeType){
ScriptEngine engine = null;
ScriptEngineFactory factory =
(ScriptEngineFactory) mimeTypeAssociations.get(mimeType);
if (factory != null) {
// gets a new instance of the Scripting Engine
engine = factory.getScriptEngine();
// sets the GLOBAL SCOPE
engine.setBindings(globalscope,ScriptContext.GLOBAL_SCOPE);
}
return engine;
}
/**
* Retrieves a new instance of a ScriptEngine the specified
* descriptieve name. Returns null if no suitable ScriptEngine is
* found.
*
* @param name the descriptive name
* @return a new instance of a ScriptEngine which supports the
* specifed descriptive name
*/
public ScriptEngine getEngineByName(String name){
ScriptEngine engine = null;
ScriptEngineFactory factory =
(ScriptEngineFactory) nameAssociations.get(name);
if (factory != null) {
engine = factory.getScriptEngine();
engine.setBindings(globalscope,ScriptContext.GLOBAL_SCOPE);
}
return engine;
}
/**
* Retrieves an array of instances of ScriptEngineFactory class
* which are found by the discovery mechanism.
*
* @return an array of all discovered ScriptEngineFactory
* instances
*/
public ScriptEngineFactory[] getEngineFactories(){
return (ScriptEngineFactory[])engineSpis.toArray();
}
/**
* Retrieves the namespace corresponds to GLOBAL_SCOPE.
*
* @return the namespace of GLOBAL_SCOPE
*/
public Bindings getBindings(){
return globalscope;
}
/**
* Associates the specifed value with the specified key in
* GLOBAL_SCOPE.
*
* @param key the associated key for specified value
* @param value the associated value for the specified key
*/
public void put(String key,Object value){
globalscope.put(key,value);
}
/**
* Register a extension with a ScriptEngineFactory class. It
* overrides any such association discovered previously.
*
* @param extension the extension associated with the specified
* ScriptEngineFactory class
* @param factory the ScriptEngineFactory class associated with
* the specified extension
*/
public void registerEngineExtension(String extension, Class factory){
extensionAssocitions.put(extension, factory);
}
/**
* Registers descriptive name with a ScriptEngineFactory class.
* It overrides any associations discovered previously.
*
* @param name a descriptive name associated with the specifed
* ScriptEngineFactory class
* @param factory the ScriptEngineFactory class associated with
* the specified descriptive name
*/
public void registerEngineName(String name, Class factory){
nameAssociations.put(name, factory);
}
/**
* Registers a MIME type with a ScriptEngineFactory class. It
* overrides any associations discovered previously.
*
* @param mimeType the MIME type associated with specified
* ScriptEngineFactory class
* @param factory the ScriptEngineFactory associated with the
* specified MIME type
*/
public void registerEngineMimeType(String mimeType,Class factory){
mimeTypeAssociations.put(mimeType,factory);
}
/**
* Sets the GLOBAL_SCOPE value to the specified namespace.
*
* @param namespace the namespace to be stored in GLOBAL_SCOPE
*/
public void setBindings(Bindings namespace){
globalscope = namespace;
}
}
