global.java

這是一個javascript 的 interpreter是了解 web browser的好材料

/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1997-1999
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Patrick Beard
 *   Igor Bukanov
 *   Norris Boyd
 *   Rob Ginda
 *   Kurt Westerfeld
 *   Matthias Radestock
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License Version 2 or later (the "GPL"), in which
 * case the provisions of the GPL are applicable instead of those above. If
 * you wish to allow use of your version of this file only under the terms of
 * the GPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replacing
 * them with the notice and other provisions required by the GPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the GPL.
 *
 * ***** END LICENSE BLOCK ***** */

package org.mozilla.javascript.tools.shell;

import java.io.*;
import java.net.*;
import java.lang.reflect.*;
import org.mozilla.javascript.*;
import org.mozilla.javascript.tools.ToolErrorReporter;
import org.mozilla.javascript.serialize.*;

/**
 * This class provides for sharing functions across multiple threads.
 * This is of particular interest to server applications.
 *
 * @author Norris Boyd
 */
public class Global extends ImporterTopLevel
{
    static final long serialVersionUID = 4029130780977538005L;

    NativeArray history;
    private InputStream inStream;
    private PrintStream outStream;
    private PrintStream errStream;
    private boolean sealedStdLib = false;
    boolean initialized;
    private QuitAction quitAction;
    private String[] prompts = { "js> ", "  > " };

    public Global()
    {
    }

    public Global(Context cx)
    {
        init(cx);
    }

    public boolean isInitialized() {
        return initialized;
    }

    /**
     * Set the action to call from quit().
     */
    public void initQuitAction(QuitAction quitAction)
    {
        if (quitAction == null)
            throw new IllegalArgumentException("quitAction is null");
        if (this.quitAction != null)
            throw new IllegalArgumentException("The method is once-call.");

        this.quitAction = quitAction;
    }

    public void init(ContextFactory factory)
    {
        factory.call(new ContextAction() {
                public Object run(Context cx)
                {
                    init(cx);
                    return null;
                }
            });
    }

    public void init(Context cx)
    {
        // Define some global functions particular to the shell. Note
        // that these functions are not part of ECMA.
        initStandardObjects(cx, sealedStdLib);
        String[] names = {
            "defineClass",
            "deserialize",
            "gc",
            "help",
            "load",
            "loadClass",
            "print",
            "quit",
            "readFile",
            "readUrl",
            "runCommand",
            "seal",
            "serialize",
            "spawn",
            "sync",
            "toint32",
            "version",
        };
        defineFunctionProperties(names, Global.class,
                                 ScriptableObject.DONTENUM);

        // Set up "environment" in the global scope to provide access to the
        // System environment variables.
        Environment.defineClass(this);
        Environment environment = new Environment(this);
        defineProperty("environment", environment,
                       ScriptableObject.DONTENUM);

        history = (NativeArray) cx.newArray(this, 0);
        defineProperty("history", history, ScriptableObject.DONTENUM);
        initialized = true;
    }

    /**
     * Print a help message.
     *
     * This method is defined as a JavaScript function.
     */
    public static void help(Context cx, Scriptable thisObj,
                            Object[] args, Function funObj)
    {
        PrintStream out = getInstance(funObj).getOut();
        out.println(ToolErrorReporter.getMessage("msg.help"));
    }

    public static void gc(Context cx, Scriptable thisObj,
            Object[] args, Function funObj)
    {
        System.gc();
    }


    /**
     * Print the string values of its arguments.
     *
     * This method is defined as a JavaScript function.
     * Note that its arguments are of the "varargs" form, which
     * allows it to handle an arbitrary number of arguments
     * supplied to the JavaScript function.
     *
     */
    public static Object print(Context cx, Scriptable thisObj,
                               Object[] args, Function funObj)
    {
        PrintStream out = getInstance(funObj).getOut();
        for (int i=0; i < args.length; i++) {
            if (i > 0)
                out.print(" ");

            // Convert the arbitrary JavaScript value into a string form.
            String s = Context.toString(args[i]);

            out.print(s);
        }
        out.println();
        return Context.getUndefinedValue();
    }

    /**
     * Call embedding-specific quit action passing its argument as
     * int32 exit code.
     *
     * This method is defined as a JavaScript function.
     */
    public static void quit(Context cx, Scriptable thisObj,
                            Object[] args, Function funObj)
    {
        Global global = getInstance(funObj);
        if (global.quitAction != null) {
            int exitCode = (args.length == 0 ? 0
                            : ScriptRuntime.toInt32(args[0]));
            global.quitAction.quit(cx, exitCode);
        }
    }

    /**
     * Get and set the language version.
     *
     * This method is defined as a JavaScript function.
     */
    public static double version(Context cx, Scriptable thisObj,
                                 Object[] args, Function funObj)
    {
        double result = cx.getLanguageVersion();
        if (args.length > 0) {
            double d = Context.toNumber(args[0]);
            cx.setLanguageVersion((int) d);
        }
        return result;
    }

    /**
     * Load and execute a set of JavaScript source files.
     *
     * This method is defined as a JavaScript function.
     *
     */
    public static void load(Context cx, Scriptable thisObj,
                            Object[] args, Function funObj)
    {
        for (int i = 0; i < args.length; i++) {
            Main.processFile(cx, thisObj, Context.toString(args[i]));
        }
    }

    /**
     * Load a Java class that defines a JavaScript object using the
     * conventions outlined in ScriptableObject.defineClass.
     * <p>
     * This method is defined as a JavaScript function.
     * @exception IllegalAccessException if access is not available
     *            to a reflected class member
     * @exception InstantiationException if unable to instantiate
     *            the named class
     * @exception InvocationTargetException if an exception is thrown
     *            during execution of methods of the named class
     * @see org.mozilla.javascript.ScriptableObject#defineClass(Scriptable,Class)
     */
    public static void defineClass(Context cx, Scriptable thisObj,
                                   Object[] args, Function funObj)
        throws IllegalAccessException, InstantiationException,
               InvocationTargetException
    {
        Class clazz = getClass(args);
        ScriptableObject.defineClass(thisObj, clazz);
    }

    /**
     * Load and execute a script compiled to a class file.
     * <p>
     * This method is defined as a JavaScript function.
     * When called as a JavaScript function, a single argument is
     * expected. This argument should be the name of a class that
     * implements the Script interface, as will any script
     * compiled by jsc.
     *
     * @exception IllegalAccessException if access is not available
     *            to the class
     * @exception InstantiationException if unable to instantiate
     *            the named class
     */
    public static void loadClass(Context cx, Scriptable thisObj,
                                 Object[] args, Function funObj)
        throws IllegalAccessException, InstantiationException
    {
        Class clazz = getClass(args);
        if (!Script.class.isAssignableFrom(clazz)) {
            throw reportRuntimeError("msg.must.implement.Script");
        }
        Script script = (Script) clazz.newInstance();
        script.exec(cx, thisObj);
    }

    private static Class getClass(Object[] args) {
        if (args.length == 0) {
            throw reportRuntimeError("msg.expected.string.arg");
        }
        Object arg0 = args[0];
        if (arg0 instanceof Wrapper) {
            Object wrapped = ((Wrapper)arg0).unwrap();
            if (wrapped instanceof Class)
                return (Class)wrapped;
        }
        String className = Context.toString(args[0]);
        try {
            return Class.forName(className);
        }
        catch (ClassNotFoundException cnfe) {
            throw reportRuntimeError("msg.class.not.found", className);
        }
    }

    public static void serialize(Context cx, Scriptable thisObj,
                                 Object[] args, Function funObj)
        throws IOException
    {
        if (args.length < 2) {
            throw Context.reportRuntimeError(
                "Expected an object to serialize and a filename to write " +
                "the serialization to");
        }
        Object obj = args[0];
        String filename = Context.toString(args[1]);
        FileOutputStream fos = new FileOutputStream(filename);
        Scriptable scope = ScriptableObject.getTopLevelScope(thisObj);
        ScriptableOutputStream out = new ScriptableOutputStream(fos, scope);
        out.writeObject(obj);
        out.close();
    }

    public static Object deserialize(Context cx, Scriptable thisObj,
                                     Object[] args, Function funObj)
        throws IOException, ClassNotFoundException
    {
        if (args.length < 1) {
            throw Context.reportRuntimeError(
                "Expected a filename to read the serialization from");
        }
        String filename = Context.toString(args[0]);
        FileInputStream fis = new FileInputStream(filename);
        Scriptable scope = ScriptableObject.getTopLevelScope(thisObj);
        ObjectInputStream in = new ScriptableInputStream(fis, scope);
        Object deserialized = in.readObject();
        in.close();
        return Context.toObject(deserialized, scope);
    }
    
    public String[] getPrompts(Context cx) {
        if (ScriptableObject.hasProperty(this, "prompts")) {
            Object promptsJS = ScriptableObject.getProperty(this,
                                                            "prompts");
            if (promptsJS instanceof Scriptable) {
                Scriptable s = (Scriptable) promptsJS;