jaroslav@0: /*
jaroslav@0: Java 4 Browser Bytecode Translator
jaroslav@0: Copyright (C) 2012-2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>
jaroslav@0: 
jaroslav@0: This program is free software: you can redistribute it and/or modify
jaroslav@0: it under the terms of the GNU General Public License as published by
jaroslav@0: the Free Software Foundation, version 2 of the License.
jaroslav@0: 
jaroslav@0: This program is distributed in the hope that it will be useful,
jaroslav@0: but WITHOUT ANY WARRANTY; without even the implied warranty of
jaroslav@0: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
jaroslav@0: GNU General Public License for more details.
jaroslav@0: 
jaroslav@0: You should have received a copy of the GNU General Public License
jaroslav@0: along with this program. Look for COPYING file in the top folder.
jaroslav@0: If not, see http://opensource.org/licenses/GPL-2.0.
jaroslav@0: */
jaroslav@0: package org.apidesign.java4browser;
jaroslav@0: 
jaroslav@0: import java.io.IOException;
jaroslav@0: import java.io.InputStream;
jaroslav@0: import java.util.List;
jaroslav@0: import org.netbeans.modules.classfile.ByteCodes;
jaroslav@0: import org.netbeans.modules.classfile.ClassFile;
jaroslav@0: import org.netbeans.modules.classfile.Code;
jaroslav@0: import org.netbeans.modules.classfile.Method;
jaroslav@0: import org.netbeans.modules.classfile.Parameter;
jaroslav@0: 
jaroslav@0: /** Translator of the code inside class files to JavaScript.
jaroslav@0:  *
jaroslav@0:  * @author Jaroslav Tulach <jtulach@netbeans.org>
jaroslav@0:  */
jaroslav@0: public final class ByteCodeToJavaScript {
jaroslav@0:     private final ClassFile jc;
jaroslav@0:     private final Appendable out;
jaroslav@0: 
jaroslav@0:     private ByteCodeToJavaScript(ClassFile jc, Appendable out) {
jaroslav@0:         this.jc = jc;
jaroslav@0:         this.out = out;
jaroslav@0:     }
jaroslav@0:     
jaroslav@0:     /** Converts a given class file to a JavaScript version.
jaroslav@0:      * @param fileName the name of the file we are reading
jaroslav@0:      * @param classFile input stream with code of the .class file
jaroslav@0:      * @param out a {@link StringBuilder} or similar to generate the output to
jaroslav@0:      * @throws IOException if something goes wrong during read or write or translating
jaroslav@0:      */
jaroslav@0:     public static void compile(String fileName, InputStream classFile, Appendable out) throws IOException {
jaroslav@0:         ClassFile jc = new ClassFile(classFile, true);
jaroslav@0:         ByteCodeToJavaScript compiler = new ByteCodeToJavaScript(jc, out);
jaroslav@0:         for (Method m : jc.getMethods()) {
jaroslav@0:             if (m.isStatic()) {
jaroslav@0:                 compiler.generateStaticMethod(m);
jaroslav@0:             }
jaroslav@0:         }
jaroslav@0:     }
jaroslav@0:     private void generateStaticMethod(Method m) throws IOException {
jaroslav@0:         out.append("function ").append(
jaroslav@0:             jc.getName().getExternalName().replace('.', '_')
jaroslav@0:         ).append('_').append(
jaroslav@0:             m.getName()
jaroslav@0:         );
jaroslav@0:         out.append(m.getReturnType());
jaroslav@0:         List<Parameter> args = m.getParameters();
jaroslav@0:         for (Parameter t : args) {
jaroslav@0:             out.append(t.getDescriptor());
jaroslav@0:         }
jaroslav@0:         out.append('(');
jaroslav@0:         String space = "";
jaroslav@0:         for (int i = 0; i < args.size(); i++) {
jaroslav@0:             out.append(space);
jaroslav@0:             out.append("arg").append(String.valueOf(i));
jaroslav@0:             space = ",";
jaroslav@0:         }
jaroslav@0:         out.append(") {").append("\n  var ");
jaroslav@0:         final Code code = m.getCode();
jaroslav@0:         int len = code.getMaxLocals();
jaroslav@0:         space = "";
jaroslav@0:         for (int i = 0; i < len; i++) {
jaroslav@0:             out.append(space);
jaroslav@0:             out.append("var").append(String.valueOf(i));
jaroslav@0:             space = ",";
jaroslav@0:         }
jaroslav@0:         out.append(";\n  var stack = new Array(");
jaroslav@0:         out.append(Integer.toString(code.getMaxStack()));
jaroslav@0:         out.append(");\n");
jaroslav@0:         produceCode(code.getByteCodes());
jaroslav@0:         out.append(";\nreturn 1;");
jaroslav@0:         out.append("}");
jaroslav@0:     }
jaroslav@0: 
jaroslav@0:     private void produceCode(byte[] byteCodes) throws IOException {
jaroslav@0:         for (int i = 0; i < byteCodes.length; i++) {
jaroslav@0:             int prev = i;
jaroslav@0:             out.append("  ");
jaroslav@0:             final int c = (byteCodes[i] + 256) % 256;
jaroslav@0:             switch (c) {
jaroslav@0:                 case ByteCodes.bc_aload_0:
jaroslav@0:                 case ByteCodes.bc_iload_0:
jaroslav@0:                     out.append("stack.push(arg0);");
jaroslav@0:                     break;
jaroslav@0:                 case ByteCodes.bc_aload_1:
jaroslav@0:                 case ByteCodes.bc_iload_1:
jaroslav@0:                     out.append("stack.push(arg1);");
jaroslav@0:                     break;
jaroslav@0:                 case ByteCodes.bc_iadd:
jaroslav@0:                     out.append("stack.push(stack.pop() + stack.pop());");
jaroslav@0:                     break;
jaroslav@0:                 case ByteCodes.bc_ireturn:
jaroslav@0:                     out.append("return stack.pop();");
jaroslav@0:             }
jaroslav@0:             out.append("/*");
jaroslav@0:             for (int j = prev; j <= i; j++) {
jaroslav@0:                 out.append(" ");
jaroslav@0:                 final int cc = (byteCodes[j] + 256) % 256;
jaroslav@0:                 out.append(Integer.toString(cc));
jaroslav@0:             }
jaroslav@0:             out.append("*/\n");
jaroslav@0:         }
jaroslav@0:     }
jaroslav@0: }