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