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/* * 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);    }}