Back to index...

	/*
	* Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package javax.script;

	import java.util.*;
	import java.io.*;

	/**
	* Simple implementation of ScriptContext.
	*
	* @author Mike Grogan
	* @since 1.6
	*/
	public class SimpleScriptContext implements ScriptContext {

	/**
	* This is the writer to be used to output from scripts.
	* By default, a <code>PrintWriter</code> based on <code>System.out</code>
	* is used. Accessor methods getWriter, setWriter are used to manage
	* this field.
	* @see java.lang.System#out
	* @see java.io.PrintWriter
	*/
	protected Writer writer;

	/**
	* This is the writer to be used to output errors from scripts.
	* By default, a <code>PrintWriter</code> based on <code>System.err</code> is
	* used. Accessor methods getErrorWriter, setErrorWriter are used to manage
	* this field.
	* @see java.lang.System#err
	* @see java.io.PrintWriter
	*/
	protected Writer errorWriter;

	/**
	* This is the reader to be used for input from scripts.
	* By default, a <code>InputStreamReader</code> based on <code>System.in</code>
	* is used and default charset is used by this reader. Accessor methods
	* getReader, setReader are used to manage this field.
	* @see java.lang.System#in
	* @see java.io.InputStreamReader
	*/
	protected Reader reader;


	/**
	* This is the engine scope bindings.
	* By default, a <code>SimpleBindings</code> is used. Accessor
	* methods setBindings, getBindings are used to manage this field.
	* @see SimpleBindings
	*/
	protected Bindings engineScope;

	/**
	* This is the global scope bindings.
	* By default, a null value (which means no global scope) is used. Accessor
	* methods setBindings, getBindings are used to manage this field.
	*/
	protected Bindings globalScope;

	/**
	* Create a {@code SimpleScriptContext}.
	*/
	public SimpleScriptContext() {
	engineScope = new SimpleBindings();
	globalScope = null;
	reader = new InputStreamReader(System.in);
	writer = new PrintWriter(System.out , true);
	errorWriter = new PrintWriter(System.err, true);
	}

	/**
	* Sets a <code>Bindings</code> of attributes for the given scope. If the value
	* of scope is <code>ENGINE_SCOPE</code> the given <code>Bindings</code> replaces the
	* <code>engineScope</code> field. If the value
	* of scope is <code>GLOBAL_SCOPE</code> the given <code>Bindings</code> replaces the
	* <code>globalScope</code> field.
	*
	* @param bindings The <code>Bindings</code> of attributes to set.
	* @param scope The value of the scope in which the attributes are set.
	*
	* @throws IllegalArgumentException if scope is invalid.
	* @throws NullPointerException if the value of scope is <code>ENGINE_SCOPE</code> and
	* the specified <code>Bindings</code> is null.
	*/
	public void setBindings(Bindings bindings, int scope) {

	switch (scope) {

	case ENGINE_SCOPE:
	if (bindings == null) {
	throw new NullPointerException("Engine scope cannot be null.");
	}
	engineScope = bindings;
	break;
	case GLOBAL_SCOPE:
	globalScope = bindings;
	break;
	default:
	throw new IllegalArgumentException("Invalid scope value.");
	}
	}


	/**
	* Retrieves the value of the attribute with the given name in
	* the scope occurring earliest in the search order. The order
	* is determined by the numeric value of the scope parameter (lowest
	* scope values first.)
	*
	* @param name The name of the the attribute to retrieve.
	* @return The value of the attribute in the lowest scope for
	* which an attribute with the given name is defined. Returns
	* null if no attribute with the name exists in any scope.
	* @throws NullPointerException if the name is null.
	* @throws IllegalArgumentException if the name is empty.
	*/
	public Object getAttribute(String name) {
	checkName(name);
	if (engineScope.containsKey(name)) {
	return getAttribute(name, ENGINE_SCOPE);
	} else if (globalScope != null && globalScope.containsKey(name)) {
	return getAttribute(name, GLOBAL_SCOPE);
	}

	return null;
	}

	/**
	* Gets the value of an attribute in a given scope.
	*
	* @param name The name of the attribute to retrieve.
	* @param scope The scope in which to retrieve the attribute.
	* @return The value of the attribute. Returns <code>null</code> is the name
	* does not exist in the given scope.
	*
	* @throws IllegalArgumentException
	* if the name is empty or if the value of scope is invalid.
	* @throws NullPointerException if the name is null.
	*/
	public Object getAttribute(String name, int scope) {
	checkName(name);
	switch (scope) {

	case ENGINE_SCOPE:
	return engineScope.get(name);

	case GLOBAL_SCOPE:
	if (globalScope != null) {
	return globalScope.get(name);
	}
	return null;

	default:
	throw new IllegalArgumentException("Illegal scope value.");
	}
	}

	/**
	* Remove an attribute in a given scope.
	*
	* @param name The name of the attribute to remove
	* @param scope The scope in which to remove the attribute
	*
	* @return The removed value.
	* @throws IllegalArgumentException
	* if the name is empty or if the scope is invalid.
	* @throws NullPointerException if the name is null.
	*/
	public Object removeAttribute(String name, int scope) {
	checkName(name);
	switch (scope) {

	case ENGINE_SCOPE:
	if (getBindings(ENGINE_SCOPE) != null) {
	return getBindings(ENGINE_SCOPE).remove(name);
	}
	return null;

	case GLOBAL_SCOPE:
	if (getBindings(GLOBAL_SCOPE) != null) {
	return getBindings(GLOBAL_SCOPE).remove(name);
	}
	return null;

	default:
	throw new IllegalArgumentException("Illegal scope value.");
	}
	}

	/**
	* Sets the value of an attribute in a given scope.
	*
	* @param name The name of the attribute to set
	* @param value The value of the attribute
	* @param scope The scope in which to set the attribute
	*
	* @throws IllegalArgumentException
	* if the name is empty or if the scope is invalid.
	* @throws NullPointerException if the name is null.
	*/
	public void setAttribute(String name, Object value, int scope) {
	checkName(name);
	switch (scope) {

	case ENGINE_SCOPE:
	engineScope.put(name, value);
	return;

	case GLOBAL_SCOPE:
	if (globalScope != null) {
	globalScope.put(name, value);
	}
	return;

	default:
	throw new IllegalArgumentException("Illegal scope value.");
	}
	}

	/** {@inheritDoc} */
	public Writer getWriter() {
	return writer;
	}

	/** {@inheritDoc} */
	public Reader getReader() {
	return reader;
	}

	/** {@inheritDoc} */
	public void setReader(Reader reader) {
	this.reader = reader;
	}

	/** {@inheritDoc} */
	public void setWriter(Writer writer) {
	this.writer = writer;
	}

	/** {@inheritDoc} */
	public Writer getErrorWriter() {
	return errorWriter;
	}

	/** {@inheritDoc} */
	public void setErrorWriter(Writer writer) {
	this.errorWriter = writer;
	}

	/**
	* Get the lowest scope in which an attribute is defined.
	* @param name Name of the attribute
	* .
	* @return The lowest scope. Returns -1 if no attribute with the given
	* name is defined in any scope.
	* @throws NullPointerException if name is null.
	* @throws IllegalArgumentException if name is empty.
	*/
	public int getAttributesScope(String name) {
	checkName(name);
	if (engineScope.containsKey(name)) {
	return ENGINE_SCOPE;
	} else if (globalScope != null && globalScope.containsKey(name)) {
	return GLOBAL_SCOPE;
	} else {
	return -1;
	}
	}

	/**
	* Returns the value of the <code>engineScope</code> field if specified scope is
	* <code>ENGINE_SCOPE</code>. Returns the value of the <code>globalScope</code> field if the specified scope is
	* <code>GLOBAL_SCOPE</code>.
	*
	* @param scope The specified scope
	* @return The value of either the <code>engineScope</code> or <code>globalScope</code> field.
	* @throws IllegalArgumentException if the value of scope is invalid.
	*/
	public Bindings getBindings(int scope) {
	if (scope == ENGINE_SCOPE) {
	return engineScope;
	} else if (scope == GLOBAL_SCOPE) {
	return globalScope;
	} else {
	throw new IllegalArgumentException("Illegal scope value.");
	}
	}

	/** {@inheritDoc} */
	public List<Integer> getScopes() {
	return scopes;
	}

	private void checkName(String name) {
	Objects.requireNonNull(name);
	if (name.isEmpty()) {
	throw new IllegalArgumentException("name cannot be empty");
	}
	}

	private static List<Integer> scopes;
	static {
	scopes = new ArrayList<Integer>(2);
	scopes.add(ENGINE_SCOPE);
	scopes.add(GLOBAL_SCOPE);
	scopes = Collections.unmodifiableList(scopes);
	}
	}

Back to index...