1 /*

     2  * Copyright 2005-2006 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package javax.script;

    27 import java.io.Reader;

    28 import java.util.Map;

    29 import java.util.Iterator;

    30 

    31 /**

    32  * Provides a standard implementation for several of the variants of the <code>eval</code>

    33  * method.

    34  * <br><br>

    35  * <code><b>eval(Reader)</b></code><p><code><b>eval(String)</b></code><p>

    36  * <code><b>eval(String, Bindings)</b></code><p><code><b>eval(Reader, Bindings)</b></code>

    37  * <br><br> are implemented using the abstract methods

    38  * <br><br>

    39  * <code><b>eval(Reader,ScriptContext)</b></code> or

    40  * <code><b>eval(String, ScriptContext)</b></code>

    41  * <br><br>

    42  * with a <code>SimpleScriptContext</code>.

    43  * <br><br>

    44  * A <code>SimpleScriptContext</code> is used as the default <code>ScriptContext</code>

    45  * of the <code>AbstractScriptEngine</code>..

    46  *

    47  * @author Mike Grogan

    48  * @since 1.6

    49  */

    50 public abstract class AbstractScriptEngine  implements ScriptEngine {

    51 

    52     /**

    53      * The default <code>ScriptContext</code> of this <code>AbstractScriptEngine</code>.

    54      */

    55 

    56     protected ScriptContext context;

    57 

    58     /**

    59      * Creates a new instance of AbstractScriptEngine using a <code>SimpleScriptContext</code>

    60      * as its default <code>ScriptContext</code>.

    61      */

    62     public AbstractScriptEngine() {

    63 

    64         context = new SimpleScriptContext();

    65 

    66     }

    67 

    68     /**

    69      * Creates a new instance using the specified <code>Bindings</code> as the

    70      * <code>ENGINE_SCOPE</code> <code>Bindings</code> in the protected <code>context</code> field.

    71      *

    72      * @param n The specified <code>Bindings</code>.

    73      * @throws NullPointerException if n is null.

    74      */

    75     public AbstractScriptEngine(Bindings n) {

    76 

    77         this();

    78         if (n == null) {

    79             throw new NullPointerException("n is null");

    80         }

    81         context.setBindings(n, ScriptContext.ENGINE_SCOPE);

    82     }

    83 

    84     /**

    85      * Sets the value of the protected <code>context</code> field to the specified

    86      * <code>ScriptContext</code>.

    87      *

    88      * @param ctxt The specified <code>ScriptContext</code>.

    89      * @throws NullPointerException if ctxt is null.

    90      */

    91     public void setContext(ScriptContext ctxt) {

    92         if (ctxt == null) {

    93             throw new NullPointerException("null context");

    94         }

    95         context = ctxt;

    96     }

    97 

    98     /**

    99      * Returns the value of the protected <code>context</code> field.

   100      *

   101      * @return The value of the protected <code>context</code> field.

   102      */

   103     public ScriptContext getContext() {

   104         return context;

   105     }

   106 

   107     /**

   108      * Returns the <code>Bindings</code> with the specified scope value in

   109      * the protected <code>context</code> field.

   110      *

   111      * @param scope The specified scope

   112      *

   113      * @return The corresponding <code>Bindings</code>.

   114      *

   115      * @throws IllegalArgumentException if the value of scope is

   116      * invalid for the type the protected <code>context</code> field.

   117      */

   118     public Bindings getBindings(int scope) {

   119 

   120         if (scope == ScriptContext.GLOBAL_SCOPE) {

   121             return context.getBindings(ScriptContext.GLOBAL_SCOPE);

   122         } else if (scope == ScriptContext.ENGINE_SCOPE) {

   123             return context.getBindings(ScriptContext.ENGINE_SCOPE);

   124         } else {

   125             throw new IllegalArgumentException("Invalid scope value.");

   126         }

   127     }

   128 

   129     /**

   130      * Sets the <code>Bindings</code> with the corresponding scope value in the

   131      * <code>context</code> field.

   132      *

   133      * @param bindings The specified <code>Bindings</code>.

   134      * @param scope The specified scope.

   135      *

   136      * @throws IllegalArgumentException if the value of scope is

   137      * invalid for the type the <code>context</code> field.

   138      * @throws NullPointerException if the bindings is null and the scope is

   139      * <code>ScriptContext.ENGINE_SCOPE</code>

   140      */

   141     public void setBindings(Bindings bindings, int scope) {

   142 

   143         if (scope == ScriptContext.GLOBAL_SCOPE) {

   144             context.setBindings(bindings, ScriptContext.GLOBAL_SCOPE);;

   145         } else if (scope == ScriptContext.ENGINE_SCOPE) {

   146             context.setBindings(bindings, ScriptContext.ENGINE_SCOPE);;

   147         } else {

   148             throw new IllegalArgumentException("Invalid scope value.");

   149         }

   150     }

   151 

   152     /**

   153      * Sets the specified value with the specified key in the <code>ENGINE_SCOPE</code>

   154      * <code>Bindings</code> of the protected <code>context</code> field.

   155      *

   156      * @param key The specified key.

   157      * @param value The specified value.

   158      *

   159      * @throws NullPointerException if key is null.

   160      * @throws IllegalArgumentException if key is empty.

   161      */

   162     public void put(String key, Object value) {

   163 

   164         Bindings nn = getBindings(ScriptContext.ENGINE_SCOPE);

   165         if (nn != null) {

   166             nn.put(key, value);

   167         }

   168 

   169     }

   170 

   171     /**

   172      * Gets the value for the specified key in the <code>ENGINE_SCOPE</code> of the

   173      * protected <code>context</code> field.

   174      *

   175      * @return The value for the specified key.

   176      *

   177      * @throws NullPointerException if key is null.

   178      * @throws IllegalArgumentException if key is empty.

   179      */

   180     public Object get(String key) {

   181 

   182         Bindings nn = getBindings(ScriptContext.ENGINE_SCOPE);

   183         if (nn != null) {

   184             return nn.get(key);

   185         }

   186 

   187         return null;

   188     }

   189 

   190 

   191     /**

   192      * <code>eval(Reader, Bindings)</code> calls the abstract

   193      * <code>eval(Reader, ScriptContext)</code> method, passing it a <code>ScriptContext</code>

   194      * whose Reader, Writers and Bindings for scopes other that <code>ENGINE_SCOPE</code>

   195      * are identical to those members of the protected <code>context</code> field.  The specified

   196      * <code>Bindings</code> is used instead of the <code>ENGINE_SCOPE</code>

   197      *

   198      * <code>Bindings</code> of the <code>context</code> field.

   199      *

   200      * @param reader A <code>Reader</code> containing the source of the script.

   201      * @param bindings A <code>Bindings</code> to use for the <code>ENGINE_SCOPE</code>

   202      * while the script executes.

   203      *

   204      * @return The return value from <code>eval(Reader, ScriptContext)</code>

   205      * @throws ScriptException if an error occurs in script.

   206      * @throws NullPointerException if any of the parameters is null.

   207      */

   208     public Object eval(Reader reader, Bindings bindings ) throws ScriptException {

   209 

   210         ScriptContext ctxt = getScriptContext(bindings);

   211 

   212         return eval(reader, ctxt);

   213     }

   214 

   215 

   216     /**

   217      * Same as <code>eval(Reader, Bindings)</code> except that the abstract

   218      * <code>eval(String, ScriptContext)</code> is used.

   219      *

   220      * @param script A <code>String</code> containing the source of the script.

   221      *

   222      * @param bindings A <code>Bindings</code> to use as the <code>ENGINE_SCOPE</code>

   223      * while the script executes.

   224      *

   225      * @return The return value from <code>eval(String, ScriptContext)</code>

   226      * @throws ScriptException if an error occurs in script.

   227      * @throws NullPointerException if any of the parameters is null.

   228      */

   229     public Object eval(String script, Bindings bindings) throws ScriptException {

   230 

   231         ScriptContext ctxt = getScriptContext(bindings);

   232 

   233         return eval(script , ctxt);

   234     }

   235 

   236     /**

   237      * <code>eval(Reader)</code> calls the abstract

   238      * <code>eval(Reader, ScriptContext)</code> passing the value of the <code>context</code>

   239      * field.

   240      *

   241      * @param reader A <code>Reader</code> containing the source of the script.

   242      * @return The return value from <code>eval(Reader, ScriptContext)</code>

   243      * @throws ScriptException if an error occurs in script.

   244      * @throws NullPointerException if any of the parameters is null.

   245      */

   246     public Object eval(Reader reader) throws ScriptException {

   247 

   248 

   249         return eval(reader, context);

   250     }

   251 

   252     /**

   253      * Same as <code>eval(Reader)</code> except that the abstract

   254      * <code>eval(String, ScriptContext)</code> is used.

   255      *

   256      * @param script A <code>String</code> containing the source of the script.

   257      * @return The return value from <code>eval(String, ScriptContext)</code>

   258      * @throws ScriptException if an error occurrs in script.

   259      * @throws NullPointerException if any of the parameters is null.

   260      */

   261     public Object eval(String script) throws ScriptException {

   262 

   263 

   264         return eval(script, context);

   265     }

   266 

   267     /**

   268      * Returns a <code>SimpleScriptContext</code>.  The <code>SimpleScriptContext</code>:

   269      *<br><br>

   270      * <ul>

   271      * <li>Uses the specified <code>Bindings</code> for its <code>ENGINE_SCOPE</code>

   272      * </li>

   273      * <li>Uses the <code>Bindings</code> returned by the abstract <code>getGlobalScope</code>

   274      * method as its <code>GLOBAL_SCOPE</code>

   275      * </li>

   276      * <li>Uses the Reader and Writer in the default <code>ScriptContext</code> of this

   277      * <code>ScriptEngine</code>

   278      * </li>

   279      * </ul>

   280      * <br><br>

   281      * A <code>SimpleScriptContext</code> returned by this method is used to implement eval methods

   282      * using the abstract <code>eval(Reader,Bindings)</code> and <code>eval(String,Bindings)</code>

   283      * versions.

   284      *

   285      * @param nn Bindings to use for the <code>ENGINE_SCOPE</code>

   286      * @return The <code>SimpleScriptContext</code>

   287      */

   288     protected ScriptContext getScriptContext(Bindings nn) {

   289 

   290         SimpleScriptContext ctxt = new SimpleScriptContext();

   291         Bindings gs = getBindings(ScriptContext.GLOBAL_SCOPE);

   292 

   293         if (gs != null) {

   294             ctxt.setBindings(gs, ScriptContext.GLOBAL_SCOPE);

   295         }

   296 

   297         if (nn != null) {

   298             ctxt.setBindings(nn,

   299                     ScriptContext.ENGINE_SCOPE);

   300         } else {

   301             throw new NullPointerException("Engine scope Bindings may not be null.");

   302         }

   303 

   304         ctxt.setReader(context.getReader());

   305         ctxt.setWriter(context.getWriter());

   306         ctxt.setErrorWriter(context.getErrorWriter());

   307 

   308         return ctxt;

   309 

   310     }

   311 }