hg/bck2brwsr: src/main/java/org/apidesign/java4browser/ByteCodeToJavaScript.java@f352a33fb71b

     1 /*

     2 Java 4 Browser Bytecode Translator

     3 Copyright (C) 2012-2012 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.

    17 */

    18 package org.apidesign.java4browser;

    20 import java.io.IOException;

    21 import java.io.InputStream;

    22 import java.util.List;

    23 import static org.netbeans.modules.classfile.ByteCodes.*;

    24 import org.netbeans.modules.classfile.CPMethodInfo;

    25 import org.netbeans.modules.classfile.ClassFile;

    26 import org.netbeans.modules.classfile.Code;

    27 import org.netbeans.modules.classfile.Method;

    28 import org.netbeans.modules.classfile.Parameter;

    30 /** Translator of the code inside class files to JavaScript.

    31  *

    32  * @author Jaroslav Tulach <jtulach@netbeans.org>

    33  */

    34 public final class ByteCodeToJavaScript {

    35     private final ClassFile jc;

    36     private final Appendable out;

    38     private ByteCodeToJavaScript(ClassFile jc, Appendable out) {

    39         this.jc = jc;

    40         this.out = out;

    41     }

    43     /** Converts a given class file to a JavaScript version.

    44      * @param fileName the name of the file we are reading

    45      * @param classFile input stream with code of the .class file

    46      * @param out a {@link StringBuilder} or similar to generate the output to

    47      * @throws IOException if something goes wrong during read or write or translating

    48      */

    49     public static void compile(String fileName, InputStream classFile, Appendable out) throws IOException {

    50         ClassFile jc = new ClassFile(classFile, true);

    51         ByteCodeToJavaScript compiler = new ByteCodeToJavaScript(jc, out);

    52         for (Method m : jc.getMethods()) {

    53             if (m.isStatic()) {

    54                 compiler.generateStaticMethod(m);

    55             }

    56         }

    57     }

    58     private void generateStaticMethod(Method m) throws IOException {

    59         out.append("\nfunction ").append(

    60             jc.getName().getExternalName().replace('.', '_')

    61         ).append('_').append(

    62             m.getName()

    63         );

    64         out.append(m.getReturnType());

    65         List<Parameter> args = m.getParameters();

    66         for (Parameter t : args) {

    67             out.append(t.getDescriptor());

    68         }

    69         out.append('(');

    70         String space = "";

    71         for (int index = 0, i = 0; i < args.size(); i++) {

    72             out.append(space);

    73             out.append("arg").append(String.valueOf(index));

    74             space = ",";

    75             final String desc = args.get(i).getDescriptor();

    76             if ("D".equals(desc) || "J".equals(desc)) {

    77                 index += 2;

    78             } else {

    79                 index++;

    80             }

    81         }

    82         out.append(") {").append("\n  var ");

    83         final Code code = m.getCode();

    84         int len = code.getMaxLocals();

    85         space = "";

    86         for (int i = 0; i < len; i++) {

    87             out.append(space);

    88             out.append("var").append(String.valueOf(i));

    89             space = ",";

    90         }

    91         out.append(";\n  var stack = new Array(");

    92         out.append(Integer.toString(code.getMaxStack()));

    93         out.append(");\n");

    94         produceCode(code.getByteCodes());

    95         out.append("}");

    96     }

    98     private void produceCode(byte[] byteCodes) throws IOException {

    99         out.append("\nvar gt = 0;\nfor(;;) switch(gt) {\n");

   100         for (int i = 0; i < byteCodes.length; i++) {

   101             int prev = i;

   102             out.append("  case " + i).append(": ");

   103             final int c = (byteCodes[i] + 256) % 256;

   104             switch (c) {

   105                 case bc_aload_0:

   106                 case bc_iload_0:

   107                 case bc_lload_0:

   108                 case bc_fload_0:

   109                 case bc_dload_0:

   110                     out.append("stack.push(arg0);");

   111                     break;

   112                 case bc_aload_1:

   113                 case bc_iload_1:

   114                 case bc_lload_1:

   115                 case bc_fload_1:

   116                 case bc_dload_1:

   117                     out.append("stack.push(arg1);");

   118                     break;

   119                 case bc_aload_2:

   120                 case bc_iload_2:

   121                 case bc_lload_2:

   122                 case bc_fload_2:

   123                 case bc_dload_2:

   124                     out.append("stack.push(arg2);");

   125                     break;

   126                 case bc_aload_3:

   127                 case bc_iload_3:

   128                 case bc_lload_3:

   129                 case bc_fload_3:

   130                 case bc_dload_3:

   131                     out.append("stack.push(arg3);");

   132                     break;

   133                 case bc_iload:

   134                 case bc_lload:

   135                 case bc_fload:

   136                 case bc_dload:

   137                 case bc_aload: {

   138                     final int indx = (byteCodes[++i] + 256) % 256;

   139                     out.append("stack.push(arg").append(indx + ");");

   140                     break;

   141                 }

   142                 case bc_iadd:

   143                 case bc_ladd:

   144                 case bc_fadd:

   145                 case bc_dadd:

   146                     out.append("stack.push(stack.pop() + stack.pop());");

   147                     break;

   148                 case bc_isub:

   149                 case bc_lsub:

   150                 case bc_fsub:

   151                 case bc_dsub:

   152                     out.append("{ var tmp = stack.pop(); stack.push(stack.pop() - tmp); }");

   153                     break;

   154                 case bc_imul:

   155                 case bc_lmul:

   156                 case bc_fmul:

   157                 case bc_dmul:

   158                     out.append("stack.push(stack.pop() * stack.pop());");

   159                     break;

   160                 case bc_idiv:

   161                 case bc_ldiv:

   162                     out.append("{ var tmp = stack.pop(); stack.push(Math.floor(stack.pop() / tmp)); }");

   163                     break;

   164                 case bc_fdiv:

   165                 case bc_ddiv:

   166                     out.append("{ var tmp = stack.pop(); stack.push(stack.pop() / tmp); }");

   167                     break;

   168                 case bc_ireturn:

   169                 case bc_lreturn:

   170                 case bc_freturn:

   171                 case bc_dreturn:

   172                     out.append("return stack.pop();");

   173                     break;

   174                 case bc_i2l:

   175                 case bc_i2f:

   176                 case bc_i2d:

   177                 case bc_l2i:

   178                     // max int check?

   179                 case bc_l2f:

   180                 case bc_l2d:

   181                 case bc_f2d:

   182                 case bc_d2f:

   183                     out.append("/* number conversion */");

   184                     break;

   185                 case bc_f2i:

   186                 case bc_f2l:

   187                 case bc_d2i:

   188                 case bc_d2l:

   189                     out.append("stack.push(Math.floor(stack.pop()));");

   190                     break;

   191                 case bc_i2b:

   192                 case bc_i2c:

   193                 case bc_i2s:

   194                     out.append("/* number conversion */");

   195                     break;

   196                 case bc_iconst_0:

   197                 case bc_dconst_0:

   198                 case bc_lconst_0:

   199                 case bc_fconst_0:

   200                     out.append("stack.push(0);");

   201                     break;

   202                 case bc_iconst_1:

   203                 case bc_lconst_1:

   204                 case bc_fconst_1:

   205                 case bc_dconst_1:

   206                     out.append("stack.push(1);");

   207                     break;

   208                 case bc_iconst_2:

   209                 case bc_fconst_2:

   210                     out.append("stack.push(2);");

   211                     break;

   212                 case bc_iconst_3:

   213                     out.append("stack.push(3);");

   214                     break;

   215                 case bc_iconst_4:

   216                     out.append("stack.push(4);");

   217                     break;

   218                 case bc_iconst_5:

   219                     out.append("stack.push(5);");

   220                     break;

   221                 case bc_if_icmpeq: {

   222                     i = generateIf(byteCodes, i, "==");

   223                     break;

   224                 }

   225                 case bc_if_icmpne:

   226                     i = generateIf(byteCodes, i, "!=");

   227                     break;

   228                 case bc_if_icmplt:

   229                     i = generateIf(byteCodes, i, ">");

   230                     break;

   231                 case bc_if_icmple:

   232                     i = generateIf(byteCodes, i, ">=");

   233                     break;

   234                 case bc_if_icmpgt:

   235                     i = generateIf(byteCodes, i, "<");

   236                     break;

   237                 case bc_if_icmpge:

   238                     i = generateIf(byteCodes, i, "<=");

   239                     break;

   240                 case bc_invokestatic: {

   241                     int methodIndex = readIntArg(byteCodes, i);

   242                     CPMethodInfo mi = (CPMethodInfo) jc.getConstantPool().get(methodIndex);

   243                     boolean[] hasReturn = { false };

   244                     StringBuilder signature = new StringBuilder();

   245                     int cnt = countArgs(mi.getDescriptor(), hasReturn, signature);

   247                     if (hasReturn[0]) {

   248                         out.append("stack.push(");

   249                     }

   250                     out.append(mi.getClassName().getInternalName().replace('/', '_'));

   251                     out.append('_');

   252                     out.append(mi.getName());

   253                     out.append(signature.toString());

   254                     out.append('(');

   255                     String sep = "";

   256                     for (int j = 0; j < cnt; j++) {

   257                         out.append(sep);

   258                         out.append("stack.pop()");

   259                         sep = ", ";

   260                     }

   261                     out.append(")");

   262                     if (hasReturn[0]) {

   263                         out.append(")");

   264                     }

   265                     out.append(";");

   266                     i += 2;

   267                     break;

   268                 }

   269             }

   270             out.append(" /*");

   271             for (int j = prev; j <= i; j++) {

   272                 out.append(" ");

   273                 final int cc = (byteCodes[j] + 256) % 256;

   274                 out.append(Integer.toString(cc));

   275             }

   276             out.append("*/\n");

   277         }

   278         out.append("}\n");

   279     }

   281     private int generateIf(byte[] byteCodes, int i, final String test) throws IOException {

   282         int indx = i + readIntArg(byteCodes, i);

   283         out.append("if (stack.pop() ").append(test).append(" stack.pop()) { gt = " + indx);

   284         out.append("; continue; }");

   285         return i + 2;

   286     }

   288     private int readIntArg(byte[] byteCodes, int offsetInstruction) {

   289         final int indxHi = (byteCodes[offsetInstruction + 1] + 256) % 256;

   290         final int indxLo = (byteCodes[offsetInstruction + 2] + 256) % 256;

   291         return (indxHi << 16) + indxLo;

   292     }

   294     private static int countArgs(String descriptor, boolean[] hasReturnType, StringBuilder sig) {

   295         int cnt = 0;

   296         int i = 0;

   297         Boolean count = null;

   298         while (i < descriptor.length()) {

   299             char ch = descriptor.charAt(i++);

   300             switch (ch) {

   301                 case '(':

   302                     count = true;

   303                     continue;

   304                 case ')':

   305                     count = false;

   306                     continue;

   307                 case 'B':

   308                 case 'C':

   309                 case 'D':

   310                 case 'F':

   311                 case 'I':

   312                 case 'J':

   313                 case 'S':

   314                 case 'Z':

   315                     if (count) {

   316                         cnt++;

   317                         sig.append(ch);

   318                     } else {

   319                         hasReturnType[0] = true;

   320                         sig.insert(0, ch);

   321                     }

   322                     continue;

   323                 case 'V':

   324                     assert !count;

   325                     hasReturnType[0] = false;

   326                     sig.insert(0, 'V');

   327                     continue;

   328                 case 'L':

   329                     i = descriptor.indexOf(';', i);

   330                     if (count) {

   331                         cnt++;

   332                     } else {

   333                         hasReturnType[0] = true;

   334                     }

   335                     continue;

   336                 case '[':

   337                     //arrays++;

   338                     continue;

   339                 default:

   340                     break; // invalid character

   341             }

   342         }

   343         return cnt;

   344     }

   345 }

author	Jaroslav Tulach <jaroslav.tulach@apidesign.org>
	Mon, 27 Aug 2012 13:16:29 +0200
changeset 4	f352a33fb71b
parent 3	e44f0155d946
child 5	d3193a7086e7
permissions	-rw-r--r--