main.java

javascript语言的解释器源码

            if (filename == null) {
                // print implementation version
                ps.println(cx.getImplementationVersion());
            }

            // Use the interpreter for interactive input
            cx.setOptimizationLevel(-1);

            BufferedReader in = new BufferedReader
                (new InputStreamReader(global.getIn()));
            int lineno = 1;
            boolean hitEOF = false;
            while (!hitEOF) {
                int startline = lineno;
                if (filename == null)
                    ps.print("js> ");
                ps.flush();
                String source = "";

                // Collect lines of source to compile.
                while (true) {
                    String newline;
                    try {
                        newline = in.readLine();
                    }
                    catch (IOException ioe) {
                        ps.println(ioe.toString());
                        break;
                    }
                    if (newline == null) {
                        hitEOF = true;
                        break;
                    }
                    source = source + newline + "\n";
                    lineno++;
                    if (cx.stringIsCompilableUnit(source))
                        break;
                }
                Script script = loadScriptFromSource(cx, source, "<stdin>",
                                                     lineno, null);
                if (script != null) {
                    Object result = evaluateScript(script, cx, global);
                    if (result != Context.getUndefinedValue()) {
                        try {
                            ps.println(Context.toString(result));
                        } catch (RhinoException rex) {
                            ToolErrorReporter.reportException(
                                cx.getErrorReporter(), rex);
                        }
                    }
                    NativeArray h = global.history;
                    h.put((int)h.getLength(), h, source);
                }
            }
            ps.println();
        } else {
            processFile(cx, global, filename);
        }
        System.gc();
    }

    public static void processFile(Context cx, Scriptable scope,
                                   String filename)
    {
        if (securityImpl == null) {
            processFileSecure(cx, scope, filename, null);
        } else {
            securityImpl.callProcessFileSecure(cx, scope, filename);
        }
    }

    static void processFileSecure(Context cx, Scriptable scope,
                                  String path, Object securityDomain)
    {
        Script script;
        if (path.endsWith(".class")) {
            script = loadCompiledScript(cx, path, securityDomain);
        } else {
            String source = (String)readFileOrUrl(path, true);
            if (source == null) {
                exitCode = EXITCODE_FILE_NOT_FOUND;
                return;
            }

            // Support the executable script #! syntax:  If
            // the first line begins with a '#', treat the whole
            // line as a comment.
            if (source.length() > 0 && source.charAt(0) == '#') {
                for (int i = 1; i != source.length(); ++i) {
                    int c = source.charAt(i);
                    if (c == '\n' || c == '\r') {
                        source = source.substring(i);
                        break;
                    }
                }
            }
            script = loadScriptFromSource(cx, source, path, 1, securityDomain);
        }
        if (script != null) {
            evaluateScript(script, cx, scope);
        }
    }

    public static Script loadScriptFromSource(Context cx, String scriptSource,
                                              String path, int lineno,
                                              Object securityDomain)
    {
        try {
            return cx.compileString(scriptSource, path, lineno,
                                    securityDomain);
        } catch (EvaluatorException ee) {
            // Already printed message.
            exitCode = EXITCODE_RUNTIME_ERROR;
        } catch (RhinoException rex) {
            ToolErrorReporter.reportException(
                cx.getErrorReporter(), rex);
            exitCode = EXITCODE_RUNTIME_ERROR;
        } catch (VirtualMachineError ex) {
            // Treat StackOverflow and OutOfMemory as runtime errors
            ex.printStackTrace();
            String msg = ToolErrorReporter.getMessage(
                "msg.uncaughtJSException", ex.toString());
            exitCode = EXITCODE_RUNTIME_ERROR;
            Context.reportError(msg);
        }
        return null;
    }

    private static Script loadCompiledScript(Context cx, String path,
                                             Object securityDomain)
    {
        byte[] data = (byte[])readFileOrUrl(path, false);
        if (data == null) {
            exitCode = EXITCODE_FILE_NOT_FOUND;
            return null;
        }
        // XXX: For now extract class name of compiled Script from path
        // instead of parsing class bytes
        int nameStart = path.lastIndexOf('/');
        if (nameStart < 0) {
            nameStart = 0;
        } else {
            ++nameStart;
        }
        int nameEnd = path.lastIndexOf('.');
        if (nameEnd < nameStart) {
            // '.' does not exist in path (nameEnd < 0)
            // or it comes before nameStart
            nameEnd = path.length();
        }
        String name = path.substring(nameStart, nameEnd);
        try {
            GeneratedClassLoader loader = SecurityController.createLoader(cx.getApplicationClassLoader(), securityDomain);
            Class clazz = loader.defineClass(name, data);
            loader.linkClass(clazz);
            if (!Script.class.isAssignableFrom(clazz)) {
                throw Context.reportRuntimeError("msg.must.implement.Script");
            }
            return (Script) clazz.newInstance();
         } catch (RhinoException rex) {
            ToolErrorReporter.reportException(
                cx.getErrorReporter(), rex);
            exitCode = EXITCODE_RUNTIME_ERROR;
        } catch (IllegalAccessException iaex) {
            exitCode = EXITCODE_RUNTIME_ERROR;
            Context.reportError(iaex.toString());
        } catch (InstantiationException inex) {
            exitCode = EXITCODE_RUNTIME_ERROR;
            Context.reportError(inex.toString());
        }
        return null;
    }

    public static Object evaluateScript(Script script, Context cx,
                                        Scriptable scope)
    {
        try {
            return script.exec(cx, scope);
        } catch (RhinoException rex) {
            ToolErrorReporter.reportException(
                cx.getErrorReporter(), rex);
            exitCode = EXITCODE_RUNTIME_ERROR;
        } catch (VirtualMachineError ex) {
            // Treat StackOverflow and OutOfMemory as runtime errors
            ex.printStackTrace();
            String msg = ToolErrorReporter.getMessage(
                "msg.uncaughtJSException", ex.toString());
            exitCode = EXITCODE_RUNTIME_ERROR;
            Context.reportError(msg);
        }
        return Context.getUndefinedValue();
    }

    public static InputStream getIn() {
        return getGlobal().getIn();
    }

    public static void setIn(InputStream in) {
        getGlobal().setIn(in);
    }

    public static PrintStream getOut() {
        return getGlobal().getOut();
    }

    public static void setOut(PrintStream out) {
        getGlobal().setOut(out);
    }

    public static PrintStream getErr() {
        return getGlobal().getErr();
    }

    public static void setErr(PrintStream err) {
        getGlobal().setErr(err);
    }

    /**
     * Read file or url specified by <tt>path</tt>.
     * @return file or url content as <tt>byte[]</tt> or as <tt>String</tt> if
     * <tt>convertToString</tt> is true.
     */
    private static Object readFileOrUrl(String path, boolean convertToString)
    {
        URL url = null;
        // Assume path is URL if it contains dot and there are at least
        // 2 characters in the protocol part. The later allows under Windows
        // to interpret paths with driver letter as file, not URL.
        if (path.indexOf(':') >= 2) {
            try {
                url = new URL(path);
            } catch (MalformedURLException ex) {
            }
        }

        InputStream is = null;
        int capacityHint = 0;
        if (url == null) {
            File file = new File(path);
            capacityHint = (int)file.length();
            try {
                is = new FileInputStream(file);
            } catch (IOException ex) {
                Context.reportError(ToolErrorReporter.getMessage(
                    "msg.couldnt.open", path));
                return null;
            }
        } else {
            try {
                URLConnection uc = url.openConnection();
                is = uc.getInputStream();
                capacityHint = uc.getContentLength();
                // Ignore insane values for Content-Length
                if (capacityHint > (1 << 20)) {
                    capacityHint = -1;
                }
            } catch (IOException ex) {
                Context.reportError(ToolErrorReporter.getMessage(
                    "msg.couldnt.open.url", url.toString(), ex.toString()));
                return null;
            }
        }
        if (capacityHint <= 0) {
            capacityHint = 4096;
        }

        byte[] data;
        try {
            try {
                data = Kit.readStream(is, capacityHint);
            } finally {
                is.close();
            }
        } catch (IOException ex) {
            Context.reportError(ex.toString());
            return null;
        }

        Object result;
        if (!convertToString) {
            result = data;
        } else {
            // Convert to String using the default encoding
            // XXX: Use 'charset=' argument of Content-Type if URL?
            result = new String(data);
        }
        return result;
    }

    static protected final Global global = new Global();
    static protected ToolErrorReporter errorReporter;
    static protected int exitCode = 0;
    static private final int EXITCODE_RUNTIME_ERROR = 3;
    static private final int EXITCODE_FILE_NOT_FOUND = 4;
    static boolean processStdin = true;
    static Vector fileList = new Vector(5);
    private static SecurityProxy securityImpl;
}