src/org/xwt/js/CompiledFunctionImpl.java

   1 // Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
   2 package org.xwt.js;
   3
   4 import org.xwt.util.*;
   5 import java.io.*;
   6
   7 /** a JavaScript function, compiled into bytecode */
   8 class CompiledFunctionImpl extends JS.Obj implements ByteCodes, Tokens {
   9
  10     // Fields and Accessors ///////////////////////////////////////////////
  11
  12     /** the number of formal arguments */
  13     int numFormalArgs = 20;
  14
  15     /** the source code file that this block was drawn from */
  16      String sourceName;
  17     public String getSourceName() throws JS.Exn { return sourceName; }
  18
  19     /** the line numbers */
  20      int[] line = new int[10];
  21
  22     /** the first line of this script */
  23     private int firstLine = -1;
  24
  25     /** the instructions */
  26      int[] op = new int[10];
  27
  28     /** the arguments to the instructions */
  29      Object[] arg = new Object[10];
  30
  31     /** the number of instruction/argument pairs */
  32      int size = 0;
  33     int size() { return size; }
  34
  35     /** the scope in which this function was declared; by default this function is called in a fresh subscope of the parentScope */
  36     JS.Scope parentScope;
  37
  38     // Constructors ////////////////////////////////////////////////////////
  39
  40     private CompiledFunctionImpl cloneWithNewParentScope(JS.Scope s) throws IOException {
  41         CompiledFunctionImpl ret = new JS.CompiledFunction(sourceName, firstLine, null, s);
  42         // Reuse the same op, arg, line, and size variables for the new "instance" of the function
  43         // NOTE: Neither *this* function nor the new function should be modified after this call
  44         ret.op = this.op;
  45         ret.arg = this.arg;
  46         ret.line = this.line;
  47         ret.size = this.size;
  48         ret.numFormalArgs = this.numFormalArgs;
  49         return ret;
  50     }
  51
  52     protected CompiledFunctionImpl(String sourceName, int firstLine, Reader sourceCode, JS.Scope parentScope) throws IOException {
  53         this.sourceName = sourceName;
  54         this.firstLine = firstLine;
  55         this.parentScope = parentScope;
  56         if (sourceCode == null) return;
  57         Parser p = new Parser(sourceCode, sourceName, firstLine);
  58         while(true) {
  59             int s = size();
  60             p.parseStatement(this, null);
  61             if (s == size()) break;
  62         }
  63         add(-1, LITERAL, null);
  64         add(-1, RETURN);
  65     }
  66
  67
  68
  69     // Adding and Altering Bytecodes ///////////////////////////////////////////////////
  70
  71     int get(int pos) { return op[pos]; }
  72     Object getArg(int pos) { return arg[pos]; }
  73     void set(int pos, int op_, Object arg_) { op[pos] = op_; arg[pos] = arg_; }
  74     void set(int pos, Object arg_) { arg[pos] = arg_; }
  75     int pop() { size--; arg[size] = null; return op[size]; }
  76     void paste(CompiledFunctionImpl other) { for(int i=0; i<other.size; i++) add(other.line[i], other.op[i], other.arg[i]); }
  77     CompiledFunctionImpl add(int line, int op_) { return add(line, op_, null); }
  78     CompiledFunctionImpl add(int line, int op_, Object arg_) {
  79         if (size == op.length - 1) {
  80             int[] line2 = new int[op.length * 2]; System.arraycopy(this.line, 0, line2, 0, op.length); this.line = line2;
  81             Object[] arg2 = new Object[op.length * 2]; System.arraycopy(arg, 0, arg2, 0, arg.length); arg = arg2;
  82             int[] op2 = new int[op.length * 2]; System.arraycopy(op, 0, op2, 0, op.length); op = op2;
  83         }
  84         this.line[size] = line;
  85         op[size] = op_;
  86         arg[size] = arg_;
  87         size++;
  88         return this;
  89     }
  90
  91     public static int getLine(JS.Thread cx) {
  92         if(cx.pc < 0 || cx.pc >= ((CompiledFunctionImpl)cx.currentCompiledFunction).size) return -1;
  93         return ((CompiledFunctionImpl)cx.currentCompiledFunction).line[cx.pc];
  94     }
  95
  96
  97     // Invoking the Bytecode ///////////////////////////////////////////////////////
  98
  99     /** returns false if the thread has been paused */
 100     static Object eval(final JS.Thread cx) throws JS.Exn {
 101         OUTER: for(;; cx.pc++) {
 102         try {
 103             if (cx.paused) return null;
 104             cx.bind();
 105             if (cx.currentCompiledFunction == null) return cx.stack.pop();
 106             if (cx.pc >= ((CompiledFunctionImpl)cx.currentCompiledFunction).size) return cx.stack.pop();
 107             String label = null;
 108             int curOP = cx.currentCompiledFunction.op[cx.pc];
 109             Object curArg = cx.currentCompiledFunction.arg[cx.pc];
 110             if(curOP == FINALLY_DONE) {
 111                 FinallyData fd = (FinallyData) cx.stack.pop();
 112                 if(fd == null) continue OUTER; // NOP
 113                 curOP = fd.op;
 114                 curArg = fd.arg;
 115             }
 116             switch(curOP) {
 117             case LITERAL: cx.stack.push(curArg); break;
 118             case OBJECT: cx.stack.push(new JS.Obj()); break;
 119             case ARRAY: cx.stack.push(new JS.Array(JS.toNumber(curArg).intValue())); break;
 120             case DECLARE: cx.scope.declare((String)(curArg==null ? cx.stack.peek() : curArg)); if(curArg != null) cx.stack.push(curArg); break;
 121             case TOPSCOPE: cx.stack.push(cx.scope); break;
 122             case JT: if (JS.toBoolean(cx.stack.pop())) cx.pc += JS.toNumber(curArg).intValue() - 1; break;
 123             case JF: if (!JS.toBoolean(cx.stack.pop())) cx.pc += JS.toNumber(curArg).intValue() - 1; break;
 124             case JMP: cx.pc += JS.toNumber(curArg).intValue() - 1; break;
 125             case POP: cx.stack.pop(); break;
 126             case SWAP: { Object o1 = cx.stack.pop(); Object o2 = cx.stack.pop(); cx.stack.push(o1); cx.stack.push(o2); break; }
 127             case DUP: cx.stack.push(cx.stack.peek()); break;
 128             case NEWSCOPE: cx.scope = new JS.Scope(cx.scope); break;
 129             case OLDSCOPE: cx.scope = cx.scope.getParentScope(); break;
 130             case ASSERT: if (!JS.toBoolean(cx.stack.pop())) throw je("assertion failed"); break;
 131             case BITNOT: cx.stack.push(new Long(~JS.toLong(cx.stack.pop()))); break;
 132             case BANG: cx.stack.push(new Boolean(!JS.toBoolean(cx.stack.pop()))); break;
 133
 134             case TYPEOF: {
 135                 Object o = cx.stack.pop();
 136                 if (o == null) cx.stack.push(null);
 137                 else if (o instanceof JS) cx.stack.push(((JS)o).typeName());
 138                 else if (o instanceof String) cx.stack.push("string");
 139                 else if (o instanceof Number) cx.stack.push("number");
 140                 else if (o instanceof Boolean) cx.stack.push("boolean");
 141                 else cx.stack.push("unknown");
 142                 break;
 143             }
 144
 145             case NEWFUNCTION: {
 146                 try {
 147                     cx.stack.push(((CompiledFunctionImpl)curArg).cloneWithNewParentScope(cx.scope));
 148                 } catch (IOException e) {
 149                     throw new Error("this should never happen");
 150                 }
 151                 break;
 152             }
 153
 154             case PUSHKEYS: {
 155                 Object o = cx.stack.peek();
 156                 Object[] keys = ((JS)o).keys();
 157                 JS.Array a = new JS.Array();
 158                 a.setSize(keys.length);
 159                 for(int j=0; j<keys.length; j++) a.setElementAt(keys[j], j);
 160                 cx.stack.push(a);
 161                 break;
 162             }
 163
 164             case LABEL: break;
 165             case LOOP: {
 166                 cx.stack.push(new LoopMarker(cx.pc, cx.pc > 0 && cx.currentCompiledFunction.op[cx.pc - 1] == LABEL ? (String)cx.currentCompiledFunction.arg[cx.pc - 1] : (String)null, cx.scope));
 167                 cx.stack.push(Boolean.TRUE);
 168                 break;
 169             }
 170
 171             case BREAK:
 172             case CONTINUE:
 173                 while(cx.stack.size() > 0) {
 174                     Object o = cx.stack.pop();
 175                     if (o instanceof CallMarker) ee("break or continue not within a loop");
 176                     if (o instanceof TryMarker) {
 177                         if(((TryMarker)o).finallyLoc < 0) continue; // no finally block, keep going
 178                         cx.stack.push(new FinallyData(curOP, curArg));
 179                         cx.scope = ((TryMarker)o).scope;
 180                         cx.pc = ((TryMarker)o).finallyLoc - 1;
 181                         continue OUTER;
 182                     }
 183                     if (o instanceof LoopMarker) {
 184                         if (curArg == null || curArg.equals(((LoopMarker)o).label)) {
 185                             int loopInstructionLocation = ((LoopMarker)o).location;
 186                             int endOfLoop = ((Integer)cx.currentCompiledFunction.arg[loopInstructionLocation]).intValue() + loopInstructionLocation;
 187                             cx.scope = ((LoopMarker)o).scope;
 188                             if (curOP == CONTINUE) { cx.stack.push(o); cx.stack.push(Boolean.FALSE); }
 189                             cx.pc = curOP == BREAK ? endOfLoop - 1 : loopInstructionLocation;
 190                             continue OUTER;
 191                         }
 192                     }
 193                 }
 194                 throw new Error("CONTINUE/BREAK invoked but couldn't find a LoopMarker at " + ((CompiledFunctionImpl)cx.currentCompiledFunction).sourceName + ":" + getLine(cx));
 195
 196             case TRY: {
 197                 int[] jmps = (int[]) curArg;
 198                 // jmps[0] is how far away the catch block is, jmps[1] is how far away the finally block is
 199                 // each can be < 0 if the specified block does not exist
 200                 cx.stack.push(new TryMarker(jmps[0] < 0 ? -1 : cx.pc + jmps[0], jmps[1] < 0 ? -1 : cx.pc + jmps[1], cx.scope));
 201                 break;
 202             }
 203
 204             case RETURN: {
 205                 Object retval = cx.stack.pop();
 206                 while(cx.stack.size() > 0) {
 207                     Object o = cx.stack.pop();
 208                     if (o instanceof TryMarker) {
 209                         if(((TryMarker)o).finallyLoc < 0) continue;
 210                         cx.stack.push(retval);
 211                         cx.stack.push(new FinallyData(RETURN));
 212                         cx.scope = ((TryMarker)o).scope;
 213                         cx.pc = ((TryMarker)o).finallyLoc - 1;
 214                         continue OUTER;
 215                     }
 216                     if (o instanceof CallMarker) {
 217                         cx.scope = ((CallMarker)o).scope;
 218                         cx.pc = ((CallMarker)o).pc;
 219                         cx.currentCompiledFunction = (CompiledFunction)((CallMarker)o).currentCompiledFunction;
 220                         cx.stack.push(retval);
 221                         continue OUTER;
 222                     }
 223                 }
 224                 throw new Error("error: RETURN invoked but couldn't find a CallMarker!");
 225             }
 226
 227             case PUT: {
 228                 Object val = cx.stack.pop();
 229                 Object key = cx.stack.pop();
 230                 Object target = cx.stack.peek();
 231                 if (target == null)
 232                     throw je("tried to put a value to the " + key + " property on the null value");
 233                 if (!(target instanceof JS))
 234                     throw je("tried to put a value to the " + key + " property on a " + target.getClass().getName());
 235                 if (key == null)
 236                     throw je("tried to assign \"" + (val==null?"(null)":val.toString()) + "\" to the null key");
 237                 // FIXME too many allocations here
 238                 TailCall tail = new TailCall();
 239                 ((JS)target).put(key, val, tail);
 240                 cx.stack.push(val);
 241                 if (tail.func != null) {
 242                     cx.stack.push(new CallMarker(cx));
 243                     cx.stack.push(tail.args);
 244                     cx.currentCompiledFunction = tail.func;
 245                     cx.scope = new CompiledFunctionImpl.FunctionScope("unknown", tail.func.parentScope);
 246                     cx.pc = -1;
 247                     break;
 248                 }
 249                 break;
 250             }
 251
 252             case GET:
 253             case GET_PRESERVE: {
 254                 Object o, v;
 255                 if (curOP == GET) {
 256                     v = curArg == null ? cx.stack.pop() : curArg;
 257                     o = cx.stack.pop();
 258                 } else {
 259                     v = cx.stack.pop();
 260                     o = cx.stack.peek();
 261                     cx.stack.push(v);
 262                 }
 263                 Object ret = null;
 264                 if (o == null) throw je("tried to get property \"" + v + "\" from the null value");
 265                 if (v == null) throw je("tried to get the null key from " + o);
 266                 if (o instanceof String || o instanceof Number || o instanceof Boolean)
 267                     ret = Internal.getFromPrimitive(o,v);
 268                 else if (o instanceof JS) {
 269                     ret = ((JS)o).get(v);
 270                     if (ret instanceof JS.TailCall) {
 271                         cx.stack.push(new CallMarker(cx));
 272                         cx.stack.push(((JS.TailCall)ret).args);
 273                         cx.currentCompiledFunction = ((JS.TailCall)ret).func;
 274                         cx.scope = new CompiledFunctionImpl.FunctionScope("unknown", ((JS.TailCall)ret).func.parentScope);
 275                         cx.pc = -1;
 276                         break;
 277                     }
 278                 } else
 279                     throw je("tried to get property " + v + " from a " + o.getClass().getName());
 280                 cx.stack.push(ret);
 281                 break;
 282             }
 283
 284             case CALLMETHOD:
 285             case CALL:
 286             {
 287                 JS.Array arguments = new JS.Array();
 288                 int numArgs = JS.toNumber(curArg).intValue();
 289                 arguments.setSize(numArgs);
 290                 for(int j=numArgs - 1; j >= 0; j--) arguments.setElementAt(cx.stack.pop(), j);
 291                 Object o = cx.stack.pop();
 292                 if(o == null) throw je("attempted to call null");
 293                 Object ret;
 294                 if(curOP == CALLMETHOD) {
 295                     Object method = o;
 296                     o = cx.stack.pop();
 297                     if(o instanceof String || o instanceof Number || o instanceof Boolean) {
 298                         ret = Internal.callMethodOnPrimitive(o,method,arguments);
 299                         cx.stack.push(ret);
 300                         break;
 301                     } else if (o instanceof JS) {
 302                         if (((JS)o).callMethod(method, arguments, true) == Boolean.TRUE) {
 303                             ret = ((JS)o).callMethod(method,arguments,false);
 304                             cx.stack.push(ret);
 305                             break;
 306                         } else {
 307                             o = ((JS)o).get(method);
 308                             if (o instanceof JS.TailCall) {
 309                                 cx.stack.push(new CallMarker(cx));
 310                                 cx.stack.push(((JS.TailCall)o).args);
 311                                 cx.currentCompiledFunction = ((JS.TailCall)o).func;
 312                                 cx.scope = new CompiledFunctionImpl.FunctionScope("unknown", ((JS.TailCall)o).func.parentScope);
 313                                 cx.pc = -1;
 314                                 break;
 315                             }
 316                         }
 317                     } else {
 318                         throw new JS.Exn("Tried to call a method on an object that isn't a JS object: " + o);
 319                     }
 320                 }
 321
 322                 if (o instanceof CompiledFunctionImpl) {
 323                     cx.stack.push(new CallMarker(cx));
 324                     cx.stack.push(arguments);
 325                     cx.currentCompiledFunction = (CompiledFunction)o;
 326                     cx.scope = new FunctionScope("unknown", cx.currentCompiledFunction.parentScope);
 327                     cx.pc = -1;
 328                     break;
 329
 330                 } else {
 331                     ret = ((JS.Callable)o).call(arguments);
 332                     if (ret instanceof JS.TailCall) {
 333                         cx.stack.push(new CallMarker(cx));
 334                         cx.stack.push(((JS.TailCall)ret).args);
 335                         cx.currentCompiledFunction = ((JS.TailCall)ret).func;
 336                         cx.scope = new CompiledFunctionImpl.FunctionScope("unknown", ((JS.TailCall)ret).func.parentScope);
 337                         cx.pc = -1;
 338                         break;
 339                     }
 340                 }
 341                 cx.stack.push(ret);
 342                 break;
 343             }
 344             // fall through if exception was thrown
 345             case THROW: {
 346                 Object o = cx.stack.pop();
 347                 if(o instanceof JS.Exn) throw (JS.Exn)o;
 348                 throw new JS.Exn(o);
 349             }
 350
 351             case INC: case DEC: {
 352                 boolean isPrefix = JS.toBoolean(curArg);
 353                 Object key = cx.stack.pop();
 354                 JS obj = (JS)cx.stack.pop();
 355                 Number num = JS.toNumber(obj.get(key));
 356                 Number val = new Double(curOP == INC ? num.doubleValue() + 1.0 : num.doubleValue() - 1.0);
 357                 obj.put(key, val);
 358                 cx.stack.push(isPrefix ? val : num);
 359                 break;
 360             }
 361
 362             case ASSIGN_SUB: case ASSIGN_ADD: {
 363                 Object val = cx.stack.pop();
 364                 Object old = cx.stack.pop();
 365                 Object key = cx.stack.pop();
 366                 Object obj = cx.stack.peek();
 367                 if (val instanceof CompiledFunction) {
 368                     if (obj instanceof JS.Scope) {
 369                         JS.Scope parent = (JS.Scope)obj;
 370                         while(parent.getParentScope() != null) parent = parent.getParentScope();
 371                         if (parent instanceof org.xwt.Box) {
 372                             if (curOP == ASSIGN_ADD) {
 373                                 ((org.xwt.Box)parent).addTrap(key, val);
 374                             } else {
 375                                 ((org.xwt.Box)parent).delTrap(key, val);
 376                             }
 377                             // skip over the "normal" implementation of +=/-=
 378                             cx.pc += ((Integer)curArg).intValue() - 1;
 379                             break;
 380                         }
 381                     }
 382                 }
 383                 // use the "normal" implementation
 384                 cx.stack.push(key);
 385                 cx.stack.push(old);
 386                 cx.stack.push(val);
 387                 break;
 388             }
 389
 390             case ADD: {
 391                 int count = ((Number)curArg).intValue();
 392                 if(count < 2) throw new Error("this should never happen");
 393                 if(count == 2) {
 394                     // common case
 395                     Object right = cx.stack.pop();
 396                     Object left = cx.stack.pop();
 397                     if(left instanceof String || right instanceof String) cx.stack.push(JS.toString(left).concat(JS.toString(right)));
 398                     else cx.stack.push(new Double(JS.toDouble(left) + JS.toDouble(right)));
 399                 } else {
 400                     Object[] args = new Object[count];
 401                     while(--count >= 0) args[count] = cx.stack.pop();
 402                     if(args[0] instanceof String) {
 403                         StringBuffer sb = new StringBuffer(64);
 404                         for(int i=0;i<args.length;i++) sb.append(JS.toString(args[i]));
 405                         cx.stack.push(sb.toString());
 406                     } else {
 407                         int numStrings = 0;
 408                         for(int i=0;i<args.length;i++) if(args[i] instanceof String) numStrings++;
 409                         if(numStrings == 0) {
 410                             double d = 0.0;
 411                             for(int i=0;i<args.length;i++) d += JS.toDouble(args[i]);
 412                             cx.stack.push(new Double(d));
 413                         } else {
 414                             int i=0;
 415                             StringBuffer sb = new StringBuffer(64);
 416                             if(!(args[0] instanceof String || args[1] instanceof String)) {
 417                                 double d=0.0;
 418                                 do {
 419                                     d += JS.toDouble(args[i++]);
 420                                 } while(!(args[i] instanceof String));
 421                                 sb.append(JS.toString(new Double(d)));
 422                             }
 423                             while(i < args.length) sb.append(JS.toString(args[i++]));
 424                             cx.stack.push(sb.toString());
 425                         }
 426                     }
 427                 }
 428                 break;
 429             }
 430
 431             default: {
 432                 Object right = cx.stack.pop();
 433                 Object left = cx.stack.pop();
 434                 switch(curOP) {
 435
 436                 case BITOR: cx.stack.push(new Long(JS.toLong(left) | JS.toLong(right))); break;
 437                 case BITXOR: cx.stack.push(new Long(JS.toLong(left) ^ JS.toLong(right))); break;
 438                 case BITAND: cx.stack.push(new Long(JS.toLong(left) & JS.toLong(right))); break;
 439
 440                 case SUB: cx.stack.push(new Double(JS.toDouble(left) - JS.toDouble(right))); break;
 441                 case MUL: cx.stack.push(new Double(JS.toDouble(left) * JS.toDouble(right))); break;
 442                 case DIV: cx.stack.push(new Double(JS.toDouble(left) / JS.toDouble(right))); break;
 443                 case MOD: cx.stack.push(new Double(JS.toDouble(left) % JS.toDouble(right))); break;
 444
 445                 case LSH: cx.stack.push(new Long(JS.toLong(left) << JS.toLong(right))); break;
 446                 case RSH: cx.stack.push(new Long(JS.toLong(left) >> JS.toLong(right))); break;
 447                 case URSH: cx.stack.push(new Long(JS.toLong(left) >>> JS.toLong(right))); break;
 448
 449                 case LT: case LE: case GT: case GE: {
 450                     if (left == null) left = new Integer(0);
 451                     if (right == null) right = new Integer(0);
 452                     int result = 0;
 453                     if (left instanceof String || right instanceof String) {
 454                         result = left.toString().compareTo(right.toString());
 455                     } else {
 456                         result = (int)java.lang.Math.ceil(JS.toDouble(left) - JS.toDouble(right));
 457                     }
 458                     cx.stack.push(new Boolean((curOP == LT && result < 0) || (curOP == LE && result <= 0) ||
 459                                        (curOP == GT && result > 0) || (curOP == GE && result >= 0)));
 460                     break;
 461                 }
 462
 463                 case EQ:
 464                 case NE: {
 465                     Object l = left;
 466                     Object r = right;
 467                     boolean ret;
 468                     if (l == null) { Object tmp = r; r = l; l = tmp; }
 469                     if (l == null && r == null) ret = true;
 470                     else if (r == null) ret = false; // l != null, so its false
 471                     else if (l instanceof Boolean) ret = new Boolean(JS.toBoolean(r)).equals(l);
 472                     else if (l instanceof Number) ret = JS.toNumber(r).doubleValue() == JS.toNumber(l).doubleValue();
 473                     else if (l instanceof String) ret = r != null && l.equals(r.toString());
 474                     else ret = l.equals(r);
 475                     cx.stack.push(new Boolean(curOP == EQ ? ret : !ret)); break;
 476                 }
 477
 478                 default: throw new Error("unknown opcode " + curOP);
 479                 } }
 480             }
 481         } catch(JS.Exn e) {
 482             while(cx.stack.size() > 0) {
 483                 Object o = cx.stack.pop();
 484                 if (o instanceof CatchMarker || o instanceof TryMarker) {
 485                     boolean inCatch = o instanceof CatchMarker;
 486                     if(inCatch) {
 487                         o = cx.stack.pop();
 488                         if(((TryMarker)o).finallyLoc < 0) continue; // no finally block, keep going
 489                     }
 490                     if(!inCatch && ((TryMarker)o).catchLoc >= 0) {
 491                         // run the catch block, this will implicitly run the finally block, if it exists
 492                         cx.stack.push(o);
 493                         cx.stack.push(catchMarker);
 494                         cx.stack.push(e.getObject());
 495                         cx.scope = ((TryMarker)o).scope;
 496                         cx.pc = ((TryMarker)o).catchLoc - 1;
 497                         continue OUTER;
 498                     } else {
 499                         cx.stack.push(e);
 500                         cx.stack.push(new FinallyData(THROW));
 501                         cx.scope = ((TryMarker)o).scope;
 502                         cx.pc = ((TryMarker)o).finallyLoc - 1;
 503                         continue OUTER;
 504                     }
 505                 }
 506                 // no handler found within this func
 507                 if(o instanceof CallMarker) throw e;
 508             }
 509             throw e;
 510         } // end try/catch
 511         } // end for
 512     }
 513
 514     // Debugging //////////////////////////////////////////////////////////////////////
 515
 516     public String toString() {
 517         StringBuffer sb = new StringBuffer(1024);
 518         sb.append("\n" + sourceName + ": " + firstLine + "\n");
 519         for (int i=0; i < size; i++) {
 520             sb.append(i);
 521             sb.append(": ");
 522             if (op[i] < 0)
 523                 sb.append(bytecodeToString[-op[i]]);
 524             else
 525                 sb.append(codeToString[op[i]]);
 526             sb.append(" ");
 527             sb.append(arg[i] == null ? "(no arg)" : arg[i]);
 528             if((op[i] == JF || op[i] == JT || op[i] == JMP) && arg[i] != null && arg[i] instanceof Number) {
 529                 sb.append(" jump to ").append(i+((Number) arg[i]).intValue());
 530             } else  if(op[i] == TRY) {
 531                 int[] jmps = (int[]) arg[i];
 532                 sb.append(" catch: ").append(jmps[0] < 0 ? "No catch block" : ""+(i+jmps[0]));
 533                 sb.append(" finally: ").append(jmps[1] < 0 ? "No finally block" : ""+(i+jmps[1]));
 534             }
 535             sb.append("\n");
 536         }
 537         return sb.toString();
 538     }
 539
 540     // Exception Stuff ////////////////////////////////////////////////////////////////
 541
 542     static class EvaluatorException extends RuntimeException { public EvaluatorException(String s) { super(s); } }
 543     static EvaluatorException ee(String s) { throw new EvaluatorException(((CompiledFunctionImpl)(JS.Thread.current()).currentCompiledFunction).sourceName + ":" + JS.Thread.current().getLine() + " " + s); }
 544     static JS.Exn je(String s) { throw new JS.Exn(((CompiledFunctionImpl)(JS.Thread.current()).currentCompiledFunction).sourceName + ":" + JS.Thread.current().getLine() + " " + s); }
 545
 546
 547     // FunctionScope /////////////////////////////////////////////////////////////////
 548
 549     static class FunctionScope extends JS.Scope {
 550         String sourceName;
 551         public FunctionScope(String sourceName, Scope parentScope) { super(parentScope); this.sourceName = sourceName; }
 552         public String getSourceName() { return sourceName; }
 553     }
 554
 555
 556     // Markers //////////////////////////////////////////////////////////////////////
 557
 558     public static class CallMarker {
 559         int pc;
 560         Scope scope;
 561         CompiledFunctionImpl currentCompiledFunction;
 562         public CallMarker(JS.Thread cx) { pc = cx.pc + 1; scope = cx.scope; currentCompiledFunction = cx.currentCompiledFunction; }
 563     }
 564
 565     public static class CatchMarker { public CatchMarker() { } }
 566     private static CatchMarker catchMarker = new CatchMarker();
 567
 568     public static class LoopMarker {
 569         public int location;
 570         public String label;
 571         public JS.Scope scope;
 572         public LoopMarker(int location, String label, JS.Scope scope) {
 573             this.location = location;
 574             this.label = label;
 575             this.scope = scope;
 576         }
 577     }
 578     public static class TryMarker {
 579         public int catchLoc;
 580         public int finallyLoc;
 581         public JS.Scope scope;
 582         public TryMarker(int catchLoc, int finallyLoc, JS.Scope scope) {
 583             this.catchLoc = catchLoc;
 584             this.finallyLoc = finallyLoc;
 585             this.scope = scope;
 586         }
 587     }
 588     public static class FinallyData {
 589         public int op;
 590         public Object arg;
 591         public FinallyData(int op, Object arg) { this.op = op; this.arg = arg; }
 592         public FinallyData(int op) { this(op,null); }
 593     }
 594 }
 595
 596 /** this class exists solely to work around a GCJ bug */
 597 abstract class JSCallable extends JS.Callable {
 598         public abstract Object call(JS.Array args) throws JS.Exn;
 599 }