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@2: import static org.netbeans.modules.classfile.ByteCodes.*;
jaroslav@4: import org.netbeans.modules.classfile.CPMethodInfo;
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@1:         out.append("\nfunction ").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@2:         for (int index = 0, i = 0; i < args.size(); i++) {
jaroslav@0:             out.append(space);
jaroslav@2:             out.append("arg").append(String.valueOf(index));
jaroslav@0:             space = ",";
jaroslav@2:             final String desc = args.get(i).getDescriptor();
jaroslav@3:             if ("D".equals(desc) || "J".equals(desc)) {
jaroslav@2:                 index += 2;
jaroslav@2:             } else {
jaroslav@2:                 index++;
jaroslav@2:             }
jaroslav@0:         }
jaroslav@5:         out.append(") {").append("\n");
jaroslav@0:         final Code code = m.getCode();
jaroslav@0:         int len = code.getMaxLocals();
jaroslav@5:         for (int index = args.size(), i = args.size(); i < len; i++) {
jaroslav@5:             out.append("  var ");
jaroslav@5:             out.append("arg").append(String.valueOf(i)).append(";\n");
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("}");
jaroslav@0:     }
jaroslav@0: 
jaroslav@0:     private void produceCode(byte[] byteCodes) throws IOException {
jaroslav@4:         out.append("\nvar gt = 0;\nfor(;;) switch(gt) {\n");
jaroslav@0:         for (int i = 0; i < byteCodes.length; i++) {
jaroslav@0:             int prev = i;
jaroslav@4:             out.append("  case " + i).append(": ");
jaroslav@0:             final int c = (byteCodes[i] + 256) % 256;
jaroslav@0:             switch (c) {
jaroslav@2:                 case bc_aload_0:
jaroslav@2:                 case bc_iload_0:
jaroslav@2:                 case bc_lload_0:
jaroslav@2:                 case bc_fload_0:
jaroslav@2:                 case bc_dload_0:
jaroslav@0:                     out.append("stack.push(arg0);");
jaroslav@0:                     break;
jaroslav@2:                 case bc_aload_1:
jaroslav@2:                 case bc_iload_1:
jaroslav@2:                 case bc_lload_1:
jaroslav@2:                 case bc_fload_1:
jaroslav@2:                 case bc_dload_1:
jaroslav@0:                     out.append("stack.push(arg1);");
jaroslav@0:                     break;
jaroslav@2:                 case bc_aload_2:
jaroslav@2:                 case bc_iload_2:
jaroslav@2:                 case bc_lload_2:
jaroslav@2:                 case bc_fload_2:
jaroslav@2:                 case bc_dload_2:
jaroslav@2:                     out.append("stack.push(arg2);");
jaroslav@2:                     break;
jaroslav@3:                 case bc_aload_3:
jaroslav@3:                 case bc_iload_3:
jaroslav@3:                 case bc_lload_3:
jaroslav@3:                 case bc_fload_3:
jaroslav@3:                 case bc_dload_3:
jaroslav@3:                     out.append("stack.push(arg3);");
jaroslav@3:                     break;
jaroslav@3:                 case bc_iload:
jaroslav@3:                 case bc_lload:
jaroslav@3:                 case bc_fload:
jaroslav@3:                 case bc_dload:
jaroslav@3:                 case bc_aload: {
jaroslav@3:                     final int indx = (byteCodes[++i] + 256) % 256;
jaroslav@3:                     out.append("stack.push(arg").append(indx + ");");
jaroslav@3:                     break;
jaroslav@3:                 }
jaroslav@5:                 case bc_istore_0:
jaroslav@5:                 case bc_lstore_0:
jaroslav@5:                 case bc_fstore_0:
jaroslav@5:                 case bc_dstore_0:
jaroslav@5:                     out.append("arg0 = stack.pop();");
jaroslav@5:                     break;
jaroslav@5:                 case bc_istore_1:
jaroslav@5:                 case bc_lstore_1:
jaroslav@5:                 case bc_fstore_1:
jaroslav@5:                 case bc_dstore_1:
jaroslav@5:                     out.append("arg1 = stack.pop();");
jaroslav@5:                     break;
jaroslav@5:                 case bc_istore_2:
jaroslav@5:                 case bc_lstore_2:
jaroslav@5:                 case bc_fstore_2:
jaroslav@5:                 case bc_dstore_2:
jaroslav@5:                     out.append("arg2 = stack.pop();");
jaroslav@5:                     break;
jaroslav@5:                 case bc_istore_3:
jaroslav@5:                 case bc_lstore_3:
jaroslav@5:                 case bc_fstore_3:
jaroslav@5:                 case bc_dstore_3:
jaroslav@5:                     out.append("arg3 = stack.pop();");
jaroslav@5:                     break;
jaroslav@2:                 case bc_iadd:
jaroslav@2:                 case bc_ladd:
jaroslav@2:                 case bc_fadd:
jaroslav@2:                 case bc_dadd:
jaroslav@0:                     out.append("stack.push(stack.pop() + stack.pop());");
jaroslav@0:                     break;
jaroslav@2:                 case bc_isub:
jaroslav@2:                 case bc_lsub:
jaroslav@2:                 case bc_fsub:
jaroslav@2:                 case bc_dsub:
jaroslav@3:                     out.append("{ var tmp = stack.pop(); stack.push(stack.pop() - tmp); }");
jaroslav@2:                     break;
jaroslav@2:                 case bc_imul:
jaroslav@2:                 case bc_lmul:
jaroslav@2:                 case bc_fmul:
jaroslav@2:                 case bc_dmul:
jaroslav@1:                     out.append("stack.push(stack.pop() * stack.pop());");
jaroslav@1:                     break;
jaroslav@3:                 case bc_idiv:
jaroslav@3:                 case bc_ldiv:
jaroslav@3:                     out.append("{ var tmp = stack.pop(); stack.push(Math.floor(stack.pop() / tmp)); }");
jaroslav@3:                     break;
jaroslav@3:                 case bc_fdiv:
jaroslav@3:                 case bc_ddiv:
jaroslav@3:                     out.append("{ var tmp = stack.pop(); stack.push(stack.pop() / tmp); }");
jaroslav@3:                     break;
jaroslav@5:                 case bc_iinc: {
jaroslav@5:                     final int varIndx = (byteCodes[++i] + 256) % 256;
jaroslav@5:                     final int incrBy = (byteCodes[++i] + 256) % 256;
jaroslav@5:                     if (incrBy == 1) {
jaroslav@5:                         out.append("arg" + varIndx).append("++;");
jaroslav@5:                     } else {
jaroslav@5:                         out.append("arg" + varIndx).append(" += " + incrBy).append(";");
jaroslav@5:                     }
jaroslav@5:                     break;
jaroslav@5:                 }
jaroslav@2:                 case bc_ireturn:
jaroslav@2:                 case bc_lreturn:
jaroslav@2:                 case bc_freturn:
jaroslav@2:                 case bc_dreturn:
jaroslav@0:                     out.append("return stack.pop();");
jaroslav@1:                     break;
jaroslav@2:                 case bc_i2l:
jaroslav@2:                 case bc_i2f:
jaroslav@2:                 case bc_i2d:
jaroslav@2:                 case bc_l2i:
jaroslav@3:                     // max int check?
jaroslav@2:                 case bc_l2f:
jaroslav@2:                 case bc_l2d:
jaroslav@3:                 case bc_f2d:
jaroslav@3:                 case bc_d2f:
jaroslav@3:                     out.append("/* number conversion */");
jaroslav@3:                     break;
jaroslav@2:                 case bc_f2i:
jaroslav@2:                 case bc_f2l:
jaroslav@2:                 case bc_d2i:
jaroslav@2:                 case bc_d2l:
jaroslav@3:                     out.append("stack.push(Math.floor(stack.pop()));");
jaroslav@3:                     break;
jaroslav@2:                 case bc_i2b:
jaroslav@2:                 case bc_i2c:
jaroslav@2:                 case bc_i2s:
jaroslav@2:                     out.append("/* number conversion */");
jaroslav@2:                     break;
jaroslav@4:                 case bc_iconst_0:
jaroslav@4:                 case bc_dconst_0:
jaroslav@4:                 case bc_lconst_0:
jaroslav@4:                 case bc_fconst_0:
jaroslav@4:                     out.append("stack.push(0);");
jaroslav@4:                     break;
jaroslav@4:                 case bc_iconst_1:
jaroslav@4:                 case bc_lconst_1:
jaroslav@4:                 case bc_fconst_1:
jaroslav@4:                 case bc_dconst_1:
jaroslav@4:                     out.append("stack.push(1);");
jaroslav@4:                     break;
jaroslav@4:                 case bc_iconst_2:
jaroslav@4:                 case bc_fconst_2:
jaroslav@4:                     out.append("stack.push(2);");
jaroslav@4:                     break;
jaroslav@4:                 case bc_iconst_3:
jaroslav@4:                     out.append("stack.push(3);");
jaroslav@4:                     break;
jaroslav@4:                 case bc_iconst_4:
jaroslav@4:                     out.append("stack.push(4);");
jaroslav@4:                     break;
jaroslav@4:                 case bc_iconst_5:
jaroslav@4:                     out.append("stack.push(5);");
jaroslav@4:                     break;
jaroslav@4:                 case bc_if_icmpeq: {
jaroslav@4:                     i = generateIf(byteCodes, i, "==");
jaroslav@4:                     break;
jaroslav@4:                 }
jaroslav@4:                 case bc_if_icmpne:
jaroslav@4:                     i = generateIf(byteCodes, i, "!=");
jaroslav@4:                     break;
jaroslav@4:                 case bc_if_icmplt:
jaroslav@4:                     i = generateIf(byteCodes, i, ">");
jaroslav@4:                     break;
jaroslav@4:                 case bc_if_icmple:
jaroslav@4:                     i = generateIf(byteCodes, i, ">=");
jaroslav@4:                     break;
jaroslav@4:                 case bc_if_icmpgt:
jaroslav@4:                     i = generateIf(byteCodes, i, "<");
jaroslav@4:                     break;
jaroslav@4:                 case bc_if_icmpge:
jaroslav@4:                     i = generateIf(byteCodes, i, "<=");
jaroslav@4:                     break;
jaroslav@5:                 case bc_goto: {
jaroslav@5:                     int indx = i + readIntArg(byteCodes, i);
jaroslav@5:                     out.append("gt = " + indx).append("; continue;");
jaroslav@5:                     i += 2;
jaroslav@5:                     break;
jaroslav@5:                 }
jaroslav@4:                 case bc_invokestatic: {
jaroslav@4:                     int methodIndex = readIntArg(byteCodes, i);
jaroslav@4:                     CPMethodInfo mi = (CPMethodInfo) jc.getConstantPool().get(methodIndex);
jaroslav@4:                     boolean[] hasReturn = { false };
jaroslav@4:                     StringBuilder signature = new StringBuilder();
jaroslav@4:                     int cnt = countArgs(mi.getDescriptor(), hasReturn, signature);
jaroslav@4:                     
jaroslav@4:                     if (hasReturn[0]) {
jaroslav@4:                         out.append("stack.push(");
jaroslav@4:                     }
jaroslav@4:                     out.append(mi.getClassName().getInternalName().replace('/', '_'));
jaroslav@4:                     out.append('_');
jaroslav@4:                     out.append(mi.getName());
jaroslav@4:                     out.append(signature.toString());
jaroslav@4:                     out.append('(');
jaroslav@4:                     String sep = "";
jaroslav@4:                     for (int j = 0; j < cnt; j++) {
jaroslav@4:                         out.append(sep);
jaroslav@4:                         out.append("stack.pop()");
jaroslav@4:                         sep = ", ";
jaroslav@4:                     }
jaroslav@4:                     out.append(")");
jaroslav@4:                     if (hasReturn[0]) {
jaroslav@4:                         out.append(")");
jaroslav@4:                     }
jaroslav@4:                     out.append(";");
jaroslav@4:                     i += 2;
jaroslav@4:                     break;
jaroslav@4:                 }
jaroslav@0:             }
jaroslav@3:             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@4:         out.append("}\n");
jaroslav@4:     }
jaroslav@4: 
jaroslav@4:     private int generateIf(byte[] byteCodes, int i, final String test) throws IOException {
jaroslav@4:         int indx = i + readIntArg(byteCodes, i);
jaroslav@4:         out.append("if (stack.pop() ").append(test).append(" stack.pop()) { gt = " + indx);
jaroslav@4:         out.append("; continue; }");
jaroslav@4:         return i + 2;
jaroslav@4:     }
jaroslav@4: 
jaroslav@4:     private int readIntArg(byte[] byteCodes, int offsetInstruction) {
jaroslav@5:         final int indxHi = byteCodes[offsetInstruction + 1] << 8;
jaroslav@5:         final int indxLo = byteCodes[offsetInstruction + 2];
jaroslav@5:         return (indxHi & 0xffffff00) | (indxLo & 0xff);
jaroslav@4:     }
jaroslav@4:     
jaroslav@4:     private static int countArgs(String descriptor, boolean[] hasReturnType, StringBuilder sig) {
jaroslav@4:         int cnt = 0;
jaroslav@4:         int i = 0;
jaroslav@4:         Boolean count = null;
jaroslav@4:         while (i < descriptor.length()) {
jaroslav@4:             char ch = descriptor.charAt(i++);
jaroslav@4:             switch (ch) {
jaroslav@4:                 case '(':
jaroslav@4:                     count = true;
jaroslav@4:                     continue;
jaroslav@4:                 case ')':
jaroslav@4:                     count = false;
jaroslav@4:                     continue;
jaroslav@4:                 case 'B': 
jaroslav@4:                 case 'C': 
jaroslav@4:                 case 'D': 
jaroslav@4:                 case 'F': 
jaroslav@4:                 case 'I': 
jaroslav@4:                 case 'J': 
jaroslav@4:                 case 'S': 
jaroslav@4:                 case 'Z': 
jaroslav@4:                     if (count) {
jaroslav@4:                         cnt++;
jaroslav@4:                         sig.append(ch);
jaroslav@4:                     } else {
jaroslav@4:                         hasReturnType[0] = true;
jaroslav@4:                         sig.insert(0, ch);
jaroslav@4:                     }
jaroslav@4:                     continue;
jaroslav@4:                 case 'V': 
jaroslav@4:                     assert !count;
jaroslav@4:                     hasReturnType[0] = false;
jaroslav@4:                     sig.insert(0, 'V');
jaroslav@4:                     continue;
jaroslav@4:                 case 'L':
jaroslav@4:                     i = descriptor.indexOf(';', i);
jaroslav@4:                     if (count) {
jaroslav@4:                         cnt++;
jaroslav@4:                     } else {
jaroslav@4:                         hasReturnType[0] = true;
jaroslav@4:                     }
jaroslav@4:                     continue;
jaroslav@4:                 case '[':
jaroslav@4:                     //arrays++;
jaroslav@4:                     continue;
jaroslav@4:                 default:
jaroslav@4:                     break; // invalid character
jaroslav@4:             }
jaroslav@4:         }
jaroslav@4:         return cnt;
jaroslav@0:     }
jaroslav@0: }