/*
* Copyright (c) 2005, 2006, 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;
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) {
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) {
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) {
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) {
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) {
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 static List<Integer> scopes;
static {
scopes = new ArrayList<Integer>(2);
scopes.add(ENGINE_SCOPE);
scopes.add(GLOBAL_SCOPE);
scopes = Collections.unmodifiableList(scopes);
}
}