2 * Back 2 Browser Bytecode Translator
3 * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>
5 * This program is free software: you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, version 2 of the License.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program. Look for COPYING file in the top folder.
16 * If not, see http://opensource.org/licenses/GPL-2.0.
18 package org.apidesign.vm4brwsr;
20 import java.io.IOException;
21 import java.io.InputStream;
24 /** Build your own virtual machine! Use methods in this class to generate
25 * a skeleton JVM in JavaScript that contains pre-compiled classes of your
26 * choice. The generated script defines one JavaScript method that can
27 * be used to bootstrap and load the virtual machine: <pre>
28 * var vm = bck2brwsr();
29 * var main = vm.loadClass('org.your.pkg.Main');
30 * main.main__V_3Ljava_lang_String_2(null);
32 * In case one wants to initialize the virtual machine with ability to
33 * load classes lazily when needed, one can provide a loader function to
34 * when creating the virtual machine: <pre>
35 * var vm = bck2brwsr(function(resource) {
36 * return null; // byte[] for the resource
39 * In this scenario, when a request for an unknown class is made, the loader
40 * function is asked for its byte code and the system dynamically transforms
43 * Instead of a loader function, one can also provide a URL to a JAR file.
44 * The <code>bck2brwsr</code> system will do its best to download the file
45 * and provide loader function for it automatically.
47 * One can provide as many loader functions and JAR URL references as necessary.
48 * Then the initialization code would look like:<pre>
49 * var vm = bck2brwsr(url1, url2, fnctn1, url3, functn2);
51 * The provided URLs and loader functions will be consulted one by one.
53 * @author Jaroslav Tulach <jtulach@netbeans.org>
55 public final class Bck2Brwsr {
56 private final ObfuscationLevel level;
57 private final StringArray classes;
58 private final Resources res;
59 private final boolean extension;
61 private Bck2Brwsr(ObfuscationLevel level, StringArray classes, Resources resources, boolean extension) {
63 this.classes = classes;
65 this.extension = extension;
68 /** Helper method to generate virtual machine from bytes served by a <code>resources</code>
71 * @param out the output to write the generated JavaScript to
72 * @param resources provider of class files to use
73 * @param classes additional classes to include in the generated script
74 * @throws IOException I/O exception can be thrown when something goes wrong
76 public static void generate(Appendable out, Resources resources, String... classes) throws IOException {
77 newCompiler().resources(resources).addRootClasses(classes).generate(out);
80 /** Helper method to generate virtual machine from bytes served by a class loader.
82 * @param out the output to write the generated JavaScript to
83 * @param loader class loader to load needed classes from
84 * @param classes additional classes to include in the generated script
85 * @throws IOException I/O exception can be thrown when something goes wrong
87 public static void generate(Appendable out, ClassLoader loader, String... classes) throws IOException {
88 newCompiler().resources(loader).addRootClasses(classes).generate(out);
91 /** Creates new instance of Bck2Brwsr compiler which is ready to generate
92 * empty Bck2Brwsr virtual machine. The instance can be further
93 * configured by calling chain of methods. For example:
95 * {@link #createCompiler()}.{@link #resources(org.apidesign.vm4brwsr.Bck2Brwsr.Resources) resources(loader)}.{@link #addRootClasses(java.lang.String[]) addRootClasses("your/Clazz")}.{@link #generate(java.lang.Appendable) generate(out)};
98 * @return new instance of the Bck2Brwsr compiler
101 public static Bck2Brwsr newCompiler() {
102 StringArray arr = StringArray.asList(
103 Class.class.getName().replace('.', '/'),
104 VM.class.getName().replace('.', '/'));
105 return new Bck2Brwsr(ObfuscationLevel.NONE, arr, null, false);
108 /** Creates new instance of the Bck2Brwsr compiler which inherits
109 * all values from <code>this</code> instance and adds additional classes
110 * to the list of those that should be compiled by the {@link #generate(java.lang.Appendable)}
113 * @param classes the classes to add to the compilation
114 * @return new instance of the compiler
116 public Bck2Brwsr addRootClasses(String... classes) {
117 if (classes.length == 0) {
120 return new Bck2Brwsr(level, this.classes.addAndNew(classes), res,
125 /** Changes the obfuscation level for the compiler by creating new instance
126 * which inherits all values from <code>this</code> and adjust the level
129 * @param level the new level of obfuscation
130 * @return new instance of the compiler with changed level of obfuscation
133 public Bck2Brwsr obfuscation(ObfuscationLevel level) {
134 return new Bck2Brwsr(level, classes, res, extension);
137 /** A way to change the provider of additional resources (classes) for the
140 * @param res the implementation of resources provider
141 * @return new instance of the compiler with all values remaining the same, just
142 * with different resources provider
145 public Bck2Brwsr resources(Resources res) {
146 return new Bck2Brwsr(level, classes, res, extension);
149 public Bck2Brwsr extension(boolean extension) {
150 return new Bck2Brwsr(level, classes, res, extension);
153 /** A way to change the provider of additional resources (classes) for the
154 * compiler by specifying classloader to use for loading them.
156 * @param loader class loader to load the resources from
157 * @return new instance of the compiler with all values being the same, just
158 * different resources provider
161 public Bck2Brwsr resources(final ClassLoader loader) {
162 return resources(new LdrRsrcs(loader));
165 /** Generates virtual machine based on previous configuration of the
168 * @param out the output to write the generated JavaScript to
171 public void generate(Appendable out) throws IOException {
172 Resources r = res != null ? res : new LdrRsrcs(Bck2Brwsr.class.getClassLoader());
173 if (level != ObfuscationLevel.NONE) {
175 ClosureWrapper.produceTo(out, level, r, classes, extension);
177 } catch (IOException ex) {
179 } catch (Throwable ex) {
180 out.append("/* Failed to obfuscate: " + ex.getMessage()
185 VM.compile(out, r, classes, extension);
188 /** Provider of resources (classes and other files). The
189 * {@link #generate(java.lang.Appendable, org.apidesign.vm4brwsr.Bck2Brwsr.Resources, java.lang.String[])
190 * generator method} will call back here for all classes needed during
191 * translation to JavaScript.
193 public interface Resources {
194 /** Loads given resource (class or other file like image). The
195 * resource name to load bytes for the {@link String} class
196 * would be <code>"java/lang/String.class"</code>.
198 * @param resource path to resource to load
199 * @return the input stream for the resource
200 * @throws IOException can be thrown if the loading fails on some error
201 * or the file cannot be found
203 public InputStream get(String resource) throws IOException;