/*
* 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
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*/
package javax.script;
import java.io.Reader;
import java.util.Map;
import java.util.Iterator;
/**
* Provides a standard implementation for several of the variants of the <code>eval</code>
* method.
* <br><br>
* <code><b>eval(Reader)</b></code><p><code><b>eval(String)</b></code><p>
* <code><b>eval(String, Bindings)</b></code><p><code><b>eval(Reader, Bindings)</b></code>
* <br><br> are implemented using the abstract methods
* <br><br>
* <code><b>eval(Reader,ScriptContext)</b></code> or
* <code><b>eval(String, ScriptContext)</b></code>
* <br><br>
* with a <code>SimpleScriptContext</code>.
* <br><br>
* A <code>SimpleScriptContext</code> is used as the default <code>ScriptContext</code>
* of the <code>AbstractScriptEngine</code>..
*
* @author Mike Grogan
* @since 1.6
*/
public abstract class AbstractScriptEngine implements ScriptEngine {
/**
* The default <code>ScriptContext</code> of this <code>AbstractScriptEngine</code>.
*/
protected ScriptContext context;
/**
* Creates a new instance of AbstractScriptEngine using a <code>SimpleScriptContext</code>
* as its default <code>ScriptContext</code>.
*/
public AbstractScriptEngine() {
context = new SimpleScriptContext();
}
/**
* Creates a new instance using the specified <code>Bindings</code> as the
* <code>ENGINE_SCOPE</code> <code>Bindings</code> in the protected <code>context</code> field.
*
* @param n The specified <code>Bindings</code>.
* @throws NullPointerException if n is null.
*/
public AbstractScriptEngine(Bindings n) {
this();
if (n == null) {
throw new NullPointerException("n is null");
}
context.setBindings(n, ScriptContext.ENGINE_SCOPE);
}
/**
* Sets the value of the protected <code>context</code> field to the specified
* <code>ScriptContext</code>.
*
* @param ctxt The specified <code>ScriptContext</code>.
* @throws NullPointerException if ctxt is null.
*/
public void setContext(ScriptContext ctxt) {
if (ctxt == null) {
throw new NullPointerException("null context");
}
context = ctxt;
}
/**
* Returns the value of the protected <code>context</code> field.
*
* @return The value of the protected <code>context</code> field.
*/
public ScriptContext getContext() {
return context;
}
/**
* Returns the <code>Bindings</code> with the specified scope value in
* the protected <code>context</code> field.
*
* @param scope The specified scope
*
* @return The corresponding <code>Bindings</code>.
*
* @throws IllegalArgumentException if the value of scope is
* invalid for the type the protected <code>context</code> field.
*/
public Bindings getBindings(int scope) {
if (scope == ScriptContext.GLOBAL_SCOPE) {
return context.getBindings(ScriptContext.GLOBAL_SCOPE);
} else if (scope == ScriptContext.ENGINE_SCOPE) {
return context.getBindings(ScriptContext.ENGINE_SCOPE);
} else {
throw new IllegalArgumentException("Invalid scope value.");
}
}
/**
* Sets the <code>Bindings</code> with the corresponding scope value in the
* <code>context</code> field.
*
* @param bindings The specified <code>Bindings</code>.
* @param scope The specified scope.
*
* @throws IllegalArgumentException if the value of scope is
* invalid for the type the <code>context</code> field.
* @throws NullPointerException if the bindings is null and the scope is
* <code>ScriptContext.ENGINE_SCOPE</code>
*/
public void setBindings(Bindings bindings, int scope) {
if (scope == ScriptContext.GLOBAL_SCOPE) {
context.setBindings(bindings, ScriptContext.GLOBAL_SCOPE);;
} else if (scope == ScriptContext.ENGINE_SCOPE) {
context.setBindings(bindings, ScriptContext.ENGINE_SCOPE);;
} else {
throw new IllegalArgumentException("Invalid scope value.");
}
}
/**
* Sets the specified value with the specified key in the <code>ENGINE_SCOPE</code>
* <code>Bindings</code> of the protected <code>context</code> field.
*
* @param key The specified key.
* @param value The specified value.
*
* @throws NullPointerException if key is null.
* @throws IllegalArgumentException if key is empty.
*/
public void put(String key, Object value) {
Bindings nn = getBindings(ScriptContext.ENGINE_SCOPE);
if (nn != null) {
nn.put(key, value);
}
}
/**
* Gets the value for the specified key in the <code>ENGINE_SCOPE</code> of the
* protected <code>context</code> field.
*
* @return The value for the specified key.
*
* @throws NullPointerException if key is null.
* @throws IllegalArgumentException if key is empty.
*/
public Object get(String key) {
Bindings nn = getBindings(ScriptContext.ENGINE_SCOPE);
if (nn != null) {
return nn.get(key);
}
return null;
}
/**
* <code>eval(Reader, Bindings)</code> calls the abstract
* <code>eval(Reader, ScriptContext)</code> method, passing it a <code>ScriptContext</code>
* whose Reader, Writers and Bindings for scopes other that <code>ENGINE_SCOPE</code>
* are identical to those members of the protected <code>context</code> field. The specified
* <code>Bindings</code> is used instead of the <code>ENGINE_SCOPE</code>
*
* <code>Bindings</code> of the <code>context</code> field.
*
* @param reader A <code>Reader</code> containing the source of the script.
* @param bindings A <code>Bindings</code> to use for the <code>ENGINE_SCOPE</code>
* while the script executes.
*
* @return The return value from <code>eval(Reader, ScriptContext)</code>
* @throws ScriptException if an error occurs in script.
* @throws NullPointerException if any of the parameters is null.
*/
public Object eval(Reader reader, Bindings bindings ) throws ScriptException {
ScriptContext ctxt = getScriptContext(bindings);
return eval(reader, ctxt);
}
/**
* Same as <code>eval(Reader, Bindings)</code> except that the abstract
* <code>eval(String, ScriptContext)</code> is used.
*
* @param script A <code>String</code> containing the source of the script.
*
* @param bindings A <code>Bindings</code> to use as the <code>ENGINE_SCOPE</code>
* while the script executes.
*
* @return The return value from <code>eval(String, ScriptContext)</code>
* @throws ScriptException if an error occurs in script.
* @throws NullPointerException if any of the parameters is null.
*/
public Object eval(String script, Bindings bindings) throws ScriptException {
ScriptContext ctxt = getScriptContext(bindings);
return eval(script , ctxt);
}
/**
* <code>eval(Reader)</code> calls the abstract
* <code>eval(Reader, ScriptContext)</code> passing the value of the <code>context</code>
* field.
*
* @param reader A <code>Reader</code> containing the source of the script.
* @return The return value from <code>eval(Reader, ScriptContext)</code>
* @throws ScriptException if an error occurs in script.
* @throws NullPointerException if any of the parameters is null.
*/
public Object eval(Reader reader) throws ScriptException {
return eval(reader, context);
}
/**
* Same as <code>eval(Reader)</code> except that the abstract
* <code>eval(String, ScriptContext)</code> is used.
*
* @param script A <code>String</code> containing the source of the script.
* @return The return value from <code>eval(String, ScriptContext)</code>
* @throws ScriptException if an error occurrs in script.
* @throws NullPointerException if any of the parameters is null.
*/
public Object eval(String script) throws ScriptException {
return eval(script, context);
}
/**
* Returns a <code>SimpleScriptContext</code>. The <code>SimpleScriptContext</code>:
*<br><br>
* <ul>
* <li>Uses the specified <code>Bindings</code> for its <code>ENGINE_SCOPE</code>
* </li>
* <li>Uses the <code>Bindings</code> returned by the abstract <code>getGlobalScope</code>
* method as its <code>GLOBAL_SCOPE</code>
* </li>
* <li>Uses the Reader and Writer in the default <code>ScriptContext</code> of this
* <code>ScriptEngine</code>
* </li>
* </ul>
* <br><br>
* A <code>SimpleScriptContext</code> returned by this method is used to implement eval methods
* using the abstract <code>eval(Reader,Bindings)</code> and <code>eval(String,Bindings)</code>
* versions.
*
* @param nn Bindings to use for the <code>ENGINE_SCOPE</code>
* @return The <code>SimpleScriptContext</code>
*/
protected ScriptContext getScriptContext(Bindings nn) {
SimpleScriptContext ctxt = new SimpleScriptContext();
Bindings gs = getBindings(ScriptContext.GLOBAL_SCOPE);
if (gs != null) {
ctxt.setBindings(gs, ScriptContext.GLOBAL_SCOPE);
}
if (nn != null) {
ctxt.setBindings(nn,
ScriptContext.ENGINE_SCOPE);
} else {
throw new NullPointerException("Engine scope Bindings may not be null.");
}
ctxt.setReader(context.getReader());
ctxt.setWriter(context.getWriter());
ctxt.setErrorWriter(context.getErrorWriter());
return ctxt;
}
}