1 /*
   2  * Copyright (c) 2010, 2013, Oracle and/or its affiliates. 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.nashorn.api.scripting;
  27 
  28 import java.util.Arrays;
  29 import java.util.Collections;
  30 import java.util.List;
  31 import javax.script.ScriptEngine;
  32 import javax.script.ScriptEngineFactory;
  33 import jdk.nashorn.internal.runtime.Version;
  34 import sun.reflect.Reflection;
  35 
  36 /**
  37  * JSR-223 compliant script engine factory for Nashorn. The engine answers for:
  38  * <ul>
  39  * <li>names {@code "nashorn"}, {@code "Nashorn"}, {@code "js"}, {@code "JS"}, {@code "JavaScript"},
  40  * {@code "javascript"}, {@code "ECMAScript"}, and {@code "ecmascript"};</li>
  41  * <li>MIME types {@code "application/javascript"}, {@code "application/ecmascript"}, {@code "text/javascript"}, and
  42  * {@code "text/ecmascript"};</li>
  43  * <li>as well as for the extension {@code "js"}.</li>
  44  * </ul>
  45  * Programs executing in engines created using {@link #getScriptEngine(String[])} will have the passed arguments
  46  * accessible as a global variable named {@code "arguments"}.
  47  */
  48 public final class NashornScriptEngineFactory implements ScriptEngineFactory {
  49     @Override
  50     public String getEngineName() {
  51         return (String) getParameter(ScriptEngine.ENGINE);
  52     }
  53 
  54     @Override
  55     public String getEngineVersion() {
  56         return (String) getParameter(ScriptEngine.ENGINE_VERSION);
  57     }
  58 
  59     @Override
  60     public List<String> getExtensions() {
  61         return Collections.unmodifiableList(extensions);
  62     }
  63 
  64     @Override
  65     public String getLanguageName() {
  66         return (String) getParameter(ScriptEngine.LANGUAGE);
  67     }
  68 
  69     @Override
  70     public String getLanguageVersion() {
  71         return (String) getParameter(ScriptEngine.LANGUAGE_VERSION);
  72     }
  73 
  74     @Override
  75     public String getMethodCallSyntax(final String obj, final String method, final String... args) {
  76         final StringBuilder sb = new StringBuilder().append(obj).append('.').append(method).append('(');
  77         final int len = args.length;
  78 
  79         if (len > 0) {
  80             sb.append(args[0]);
  81         }
  82         for (int i = 1; i < len; i++) {
  83             sb.append(',').append(args[i]);
  84         }
  85         sb.append(')');
  86 
  87         return sb.toString();
  88     }
  89 
  90     @Override
  91     public List<String> getMimeTypes() {
  92         return Collections.unmodifiableList(mimeTypes);
  93     }
  94 
  95     @Override
  96     public List<String> getNames() {
  97         return Collections.unmodifiableList(names);
  98     }
  99 
 100     @Override
 101     public String getOutputStatement(final String toDisplay) {
 102         return "print(" + toDisplay + ")";
 103     }
 104 
 105     @Override
 106     public Object getParameter(final String key) {
 107         switch (key) {
 108         case ScriptEngine.NAME:
 109             return "javascript";
 110         case ScriptEngine.ENGINE:
 111             return "Oracle Nashorn";
 112         case ScriptEngine.ENGINE_VERSION:
 113             return Version.version();
 114         case ScriptEngine.LANGUAGE:
 115             return "ECMAScript";
 116         case ScriptEngine.LANGUAGE_VERSION:
 117             return "ECMA - 262 Edition 5.1";
 118         case "THREADING":
 119             // The engine implementation is not thread-safe. Can't be
 120             // used to execute scripts concurrently on multiple threads.
 121             return null;
 122         default:
 123             throw new IllegalArgumentException("Invalid key");
 124         }
 125     }
 126 
 127     @Override
 128     public String getProgram(final String... statements) {
 129         final StringBuilder sb = new StringBuilder();
 130 
 131         for (final String statement : statements) {
 132             sb.append(statement).append(';');
 133         }
 134 
 135         return sb.toString();
 136     }
 137 
 138     @Override
 139     public ScriptEngine getScriptEngine() {
 140         return new NashornScriptEngine(this, getAppClassLoader());
 141     }
 142 
 143     /**










 144      * Create a new Script engine initialized by given arguments.
 145      *
 146      * @param args arguments array passed to script engine.
 147      * @return newly created script engine.
 148      */
 149     public ScriptEngine getScriptEngine(final String[] args) {
 150         return new NashornScriptEngine(this, args, getAppClassLoader());
 151     }
 152 











 153     // -- Internals only below this point
 154 
 155     private static final List<String> names;
 156     private static final List<String> mimeTypes;
 157     private static final List<String> extensions;
 158 
 159     static {
 160         names = immutableList(
 161                     "nashorn", "Nashorn",
 162                     "js", "JS",
 163                     "JavaScript", "javascript",
 164                     "ECMAScript", "ecmascript"
 165                 );
 166 
 167         mimeTypes = immutableList(
 168                         "application/javascript",
 169                         "application/ecmascript",
 170                         "text/javascript",
 171                         "text/ecmascript"
 172                     );
 173 
 174         extensions = immutableList("js");
 175     }
 176 
 177     private static List<String> immutableList(final String... elements) {
 178         return Collections.unmodifiableList(Arrays.asList(elements));
 179     }
 180 
 181     private static ClassLoader getAppClassLoader() {
 182         if (System.getSecurityManager() == null) {
 183             return ClassLoader.getSystemClassLoader();
 184         }
 185 
 186         // Try to determine the caller class loader. Use that if it can be
 187         // found. If not, use the class loader of nashorn itself as the
 188         // "application" class loader for scripts.
 189 
 190         // User could have called ScriptEngineFactory.getScriptEngine()
 191         //
 192         // <caller>
 193         //  <factory.getScriptEngine()>
 194         //   <factory.getAppClassLoader()>
 195         //    <Reflection.getCallerClass()>
 196         //
 197         // or used one of the getEngineByABC methods of ScriptEngineManager.
 198         //
 199         // <caller>
 200         //  <ScriptEngineManager.getEngineByName()>
 201         //   <factory.getScriptEngine()>
 202         //    <factory.getAppClassLoader()>
 203         //     <Reflection.getCallerClass()>
 204 
 205         // So, stack depth is 3 or 4 (recall it is zero based). We try
 206         // stack depths 3, 4 and look for non-bootstrap caller.
 207         Class<?> caller = null;
 208         for (int depth = 3; depth < 5; depth++) {
 209             caller = Reflection.getCallerClass(depth);
 210             if (caller != null && caller.getClassLoader() != null) {
 211                 // found a non-bootstrap caller
 212                 break;
 213             }
 214         }
 215 
 216         final ClassLoader ccl = (caller == null)? null : caller.getClassLoader();
 217         // if caller loader is null, then use nashorn's own loader
 218         return (ccl == null)? NashornScriptEngineFactory.class.getClassLoader() : ccl;
 219     }
 220 }
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