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Rhino is an open-source implementation of JavaScript written entirely in Java. It is typically embedded into Java applications to provide scripting to end users.
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/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.javascript;

/**
 * The JavaScript Script object.
 *
 * Note that the C version of the engine uses XDR as the format used
 * by freeze and thaw. Since this depends on the internal format of
 * structures in the C runtime, we cannot duplicate it.
 *
 * Since we cannot replace 'this' as a result of the compile method,
 * will forward requests to execute to the nonnull 'script' field.
 *
 * @since 1.3
 * @author Norris Boyd
 */

class NativeScript extends BaseFunction
{
    private static final long serialVersionUID = -6795101161980121700L;

    private static final Object SCRIPT_TAG = "Script";

    static void init(Scriptable scope, boolean sealed)
    {
        NativeScript obj = new NativeScript(null);
        obj.exportAsJSClass(MAX_PROTOTYPE_ID, scope, sealed);
    }

    private NativeScript(Script script)
    {
        this.script = script;
    }

    /**
     * Returns the name of this JavaScript class, "Script".
     */
    @Override
    public String getClassName()
    {
        return "Script";
    }

    @Override
    public Object call(Context cx, Scriptable scope, Scriptable thisObj,
                       Object[] args)
    {
        if (script != null) {
            return script.exec(cx, scope);
        }
        return Undefined.instance;
    }

    @Override
    public Scriptable construct(Context cx, Scriptable scope, Object[] args)
    {
        throw Context.reportRuntimeError0("msg.script.is.not.constructor");
    }

    @Override
    public int getLength()
    {
        return 0;
    }

    @Override
    public int getArity()
    {
        return 0;
    }

    @Override
    String decompile(int indent, int flags)
    {
        if (script instanceof NativeFunction) {
            return ((NativeFunction)script).decompile(indent, flags);
        }
        return super.decompile(indent, flags);
    }

    @Override
    protected void initPrototypeId(int id)
    {
        String s;
        int arity;
        switch (id) {
          case Id_constructor: arity=1; s="constructor"; break;
          case Id_toString:    arity=0; s="toString";    break;
          case Id_exec:        arity=0; s="exec";        break;
          case Id_compile:     arity=1; s="compile";     break;
          default: throw new IllegalArgumentException(String.valueOf(id));
        }
        initPrototypeMethod(SCRIPT_TAG, id, s, arity);
    }

    @Override
    public Object execIdCall(IdFunctionObject f, Context cx, Scriptable scope,
                             Scriptable thisObj, Object[] args)
    {
        if (!f.hasTag(SCRIPT_TAG)) {
            return super.execIdCall(f, cx, scope, thisObj, args);
        }
        int id = f.methodId();
        switch (id) {
          case Id_constructor: {
            String source = (args.length == 0)
                            ? ""
                            : ScriptRuntime.toString(args[0]);
            Script script = compile(cx, source);
            NativeScript nscript = new NativeScript(script);
            ScriptRuntime.setObjectProtoAndParent(nscript, scope);
            return nscript;
          }

          case Id_toString: {
            NativeScript real = realThis(thisObj, f);
            Script realScript = real.script;
            if (realScript == null) { return ""; }
            return cx.decompileScript(realScript, 0);
          }

          case Id_exec: {
            throw Context.reportRuntimeError1(
                "msg.cant.call.indirect", "exec");
          }

          case Id_compile: {
            NativeScript real = realThis(thisObj, f);
            String source = ScriptRuntime.toString(args, 0);
            real.script = compile(cx, source);
            return real;
          }
        }
        throw new IllegalArgumentException(String.valueOf(id));
    }

    private static NativeScript realThis(Scriptable thisObj, IdFunctionObject f)
    {
        if (!(thisObj instanceof NativeScript))
            throw incompatibleCallError(f);
        return (NativeScript)thisObj;
    }

    private static Script compile(Context cx, String source)
    {
        int[] linep = { 0 };
        String filename = Context.getSourcePositionFromStack(linep);
        if (filename == null) {
            filename = "