src/org/xwt/js/Interpreter.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.util.*;
   6 import java.io.*;
   7
   8 /** Encapsulates a single JS interpreter (ie call stack) */
   9 class Interpreter implements ByteCodes, Tokens {
  10
  11
  12     // Thread-Interpreter Mapping /////////////////////////////////////////////////////////////////////////
  13
  14     static Interpreter current() { return (Interpreter)threadToInterpreter.get(Thread.currentThread()); }
  15     private static Hashtable threadToInterpreter = new Hashtable();
  16
  17
  18     // Instance members and methods //////////////////////////////////////////////////////////////////////
  19
  20     int pausecount;               ///< the number of times pause() has been invoked; -1 indicates unpauseable
  21     JSFunction f = null;          ///< the currently-executing JSFunction
  22     JSScope scope;                ///< the current top-level scope (LIFO stack via NEWSCOPE/OLDSCOPE)
  23     Vec stack = new Vec();        ///< the object stack
  24     int pc = 0;                   ///< the program counter
  25
  26     Interpreter(JSFunction f, boolean pauseable, JSArray args) {
  27         stack.push(new Interpreter.CallMarker(this));    // the "root function returned" marker -- f==null
  28         this.f = f;
  29         this.pausecount = pauseable ? 0 : -1;
  30         this.scope = new JSScope(f.parentScope);
  31         stack.push(args);
  32     }
  33
  34     /** this is the only synchronization point we need in order to be threadsafe */
  35     synchronized Object resume() throws JSExn {
  36         Thread t = Thread.currentThread();
  37         Interpreter old = (Interpreter)threadToInterpreter.get(t);
  38         threadToInterpreter.put(t, this);
  39         try {
  40             return run();
  41         } finally {
  42             if (old == null) threadToInterpreter.remove(t);
  43             else threadToInterpreter.put(t, old);
  44         }
  45     }
  46
  47     private static JSExn je(String s) { return new JSExn(JS.getSourceName() + ":" + JS.getLine() + " " + s); }
  48
  49     // FIXME: double check the trap logic
  50     private Object run() throws JSExn {
  51
  52         // if pausecount changes after a get/put/call, we know we've been paused
  53         final int initialPauseCount = pausecount;
  54
  55         OUTER: for(;; pc++) {
  56         try {
  57             if (f == null) return stack.pop();
  58             int op = f.op[pc];
  59             Object arg = f.arg[pc];
  60             if(op == FINALLY_DONE) {
  61                 FinallyData fd = (FinallyData) stack.pop();
  62                 if(fd == null) continue OUTER; // NOP
  63                 op = fd.op;
  64                 arg = fd.arg;
  65             }
  66             switch(op) {
  67             case LITERAL: stack.push(arg); break;
  68             case OBJECT: stack.push(new JS()); break;
  69             case ARRAY: stack.push(new JSArray(JS.toNumber(arg).intValue())); break;
  70             case DECLARE: scope.declare((String)(arg==null ? stack.peek() : arg)); if(arg != null) stack.push(arg); break;
  71             case TOPSCOPE: stack.push(scope); break;
  72             case JT: if (JS.toBoolean(stack.pop())) pc += JS.toNumber(arg).intValue() - 1; break;
  73             case JF: if (!JS.toBoolean(stack.pop())) pc += JS.toNumber(arg).intValue() - 1; break;
  74             case JMP: pc += JS.toNumber(arg).intValue() - 1; break;
  75             case POP: stack.pop(); break;
  76             case SWAP: {
  77                 int depth = (arg == null ? 1 : JS.toInt(arg));
  78                 Object save = stack.elementAt(stack.size() - 1);
  79                 for(int i=stack.size() - 1; i > stack.size() - 1 - depth; i--)
  80                     stack.setElementAt(stack.elementAt(i-1), i);
  81                 stack.setElementAt(save, stack.size() - depth - 1);
  82                 break; }
  83             case DUP: stack.push(stack.peek()); break;
  84             case NEWSCOPE: scope = new JSScope(scope); break;
  85             case OLDSCOPE: scope = scope.getParentScope(); break;
  86             case ASSERT: if (!JS.toBoolean(stack.pop())) throw je("xwt.assertion.failed" /*FEATURE: line number*/); break;
  87             case BITNOT: stack.push(JS.N(~JS.toLong(stack.pop()))); break;
  88             case BANG: stack.push(JS.B(!JS.toBoolean(stack.pop()))); break;
  89             case NEWFUNCTION: stack.push(((JSFunction)arg).cloneWithNewParentScope(scope)); break;
  90             case LABEL: break;
  91
  92             case TYPEOF: {
  93                 Object o = stack.pop();
  94                 if (o == null) stack.push(null);
  95                 else if (o instanceof JS) stack.push(((JS)o).typeName());
  96                 else if (o instanceof String) stack.push("string");
  97                 else if (o instanceof Number) stack.push("number");
  98                 else if (o instanceof Boolean) stack.push("boolean");
  99                 else stack.push("unknown");
 100                 break;
 101             }
 102
 103             case PUSHKEYS: {
 104                 Object o = stack.peek();
 105                 Enumeration e = ((JS)o).keys();
 106                 JSArray a = new JSArray();
 107                 while(e.hasMoreElements()) a.addElement(e.nextElement());
 108                 stack.push(a);
 109                 break;
 110             }
 111
 112             case LOOP:
 113                 stack.push(new LoopMarker(pc, pc > 0 && f.op[pc - 1] == LABEL ? (String)f.arg[pc - 1] : (String)null, scope));
 114                 stack.push(Boolean.TRUE);
 115                 break;
 116
 117             case BREAK:
 118             case CONTINUE:
 119                 while(stack.size() > 0) {
 120                     Object o = stack.pop();
 121                     if (o instanceof CallMarker) je("break or continue not within a loop");
 122                     if (o instanceof TryMarker) {
 123                         if(((TryMarker)o).finallyLoc < 0) continue; // no finally block, keep going
 124                         stack.push(new FinallyData(op, arg));
 125                         scope = ((TryMarker)o).scope;
 126                         pc = ((TryMarker)o).finallyLoc - 1;
 127                         continue OUTER;
 128                     }
 129                     if (o instanceof LoopMarker) {
 130                         if (arg == null || arg.equals(((LoopMarker)o).label)) {
 131                             int loopInstructionLocation = ((LoopMarker)o).location;
 132                             int endOfLoop = ((Integer)f.arg[loopInstructionLocation]).intValue() + loopInstructionLocation;
 133                             scope = ((LoopMarker)o).scope;
 134                             if (op == CONTINUE) { stack.push(o); stack.push(Boolean.FALSE); }
 135                             pc = op == BREAK ? endOfLoop - 1 : loopInstructionLocation;
 136                             continue OUTER;
 137                         }
 138                     }
 139                 }
 140                 throw new Error("CONTINUE/BREAK invoked but couldn't find LoopMarker at " +
 141                                 JS.getSourceName() + ":" + JS.getLine());
 142
 143             case TRY: {
 144                 int[] jmps = (int[]) arg;
 145                 // jmps[0] is how far away the catch block is, jmps[1] is how far away the finally block is
 146                 // each can be < 0 if the specified block does not exist
 147                 stack.push(new TryMarker(jmps[0] < 0 ? -1 : pc + jmps[0], jmps[1] < 0 ? -1 : pc + jmps[1], scope));
 148                 break;
 149             }
 150
 151             case RETURN: {
 152                 Object retval = stack.pop();
 153                 while(stack.size() > 0) {
 154                     Object o = stack.pop();
 155                     if (o instanceof TryMarker) {
 156                         if(((TryMarker)o).finallyLoc < 0) continue;
 157                         stack.push(retval);
 158                         stack.push(new FinallyData(RETURN));
 159                         scope = ((TryMarker)o).scope;
 160                         pc = ((TryMarker)o).finallyLoc - 1;
 161                         continue OUTER;
 162                     } else if (o instanceof CallMarker) {
 163                         if (scope instanceof Trap.TrapScope) { // handles return component of a read trap
 164                             Trap.TrapScope ts = (Trap.TrapScope)scope;
 165                             if (retval != null) ts.cascadeHappened = true;
 166                             if (!ts.cascadeHappened) {
 167                                 ts.cascadeHappened = true;
 168                                 Trap t = ts.t.next;
 169                                 while (t != null && t.f.numFormalArgs == 0) t = t.next;
 170                                 if (t == null) {
 171                                     ((JS)ts.t.trapee).put(ts.t.name, ts.val);
 172                                     if (pausecount > initialPauseCount) { pc++; return null; }   // we were paused
 173                                 } else {
 174                                     stack.push(o);
 175                                     JSArray args = new JSArray();
 176                                     args.addElement(ts.val);
 177                                     stack.push(args);
 178                                     f = t.f;
 179                                     scope = new Trap.TrapScope(f.parentScope, t, ts.val);
 180                                     pc = -1;
 181                                     continue OUTER;
 182                                 }
 183                             }
 184                         }
 185                         scope = ((CallMarker)o).scope;
 186                         pc = ((CallMarker)o).pc - 1;
 187                         f = (JSFunction)((CallMarker)o).f;
 188                         stack.push(retval);
 189                         continue OUTER;
 190                     }
 191                 }
 192                 throw new Error("error: RETURN invoked but couldn't find a CallMarker!");
 193             }
 194
 195             case PUT: {
 196                 Object val = stack.pop();
 197                 Object key = stack.pop();
 198                 Object target = stack.peek();
 199                 if (target == null)
 200                     throw je("tried to put a value to the " + key + " property on the null value");
 201                 if (!(target instanceof JS))
 202                     throw je("tried to put a value to the " + key + " property on a " + target.getClass().getName());
 203                 if (key == null)
 204                     throw je("tried to assign \"" + (val==null?"(null)":val.toString()) + "\" to the null key");
 205
 206                 Trap t = null;
 207                 if (target instanceof Trap.TrapScope && key.equals("cascade")) {
 208                     Trap.TrapScope ts = (Trap.TrapScope)target;
 209                     t = ts.t.next;
 210                     ts.cascadeHappened = true;
 211                     while (t != null && t.f.numFormalArgs == 0) t = t.next;
 212                     if (t == null) { target = ts.t.trapee; key = ts.t.name; }
 213
 214                 } else if (target instanceof Trap.TrapScope && key.equals(((Trap.TrapScope)target).t.name)) {
 215                     throw je("tried to put to " + key + " inside a trap it owns; use cascade instead");
 216
 217                 } else if (target instanceof JS) {
 218                     if (target instanceof JSScope) {
 219                         JSScope p = (JSScope)target; // search the scope-path for the trap
 220                         t = p.getTrap(key);
 221                         while (t == null && p.getParentScope() != null) { p = p.getParentScope(); t = p.getTrap(key); }
 222                     } else {
 223                         t = ((JS)target).getTrap(key);
 224                     }
 225
 226                     while (t != null && t.f.numFormalArgs == 0) t = t.next; // find the first write trap
 227                     if (t != null) {
 228                         stack.push(new CallMarker(this));
 229                         JSArray args = new JSArray();
 230                         args.addElement(val);
 231                         stack.push(args);
 232                     }
 233                 }
 234                 if (t != null) {
 235                     f = t.f;
 236                     scope = new Trap.TrapScope(f.parentScope, t, val);
 237                     pc = -1;
 238                     break;
 239                 }
 240                 ((JS)target).put(key, val);
 241                 if (pausecount > initialPauseCount) { pc++; return null; }   // we were paused
 242                 stack.push(val);
 243                 break;
 244             }
 245
 246             case GET:
 247             case GET_PRESERVE: {
 248                 Object o, v;
 249                 if (op == GET) {
 250                     v = arg == null ? stack.pop() : arg;
 251                     o = stack.pop();
 252                 } else {
 253                     v = stack.pop();
 254                     o = stack.peek();
 255                     stack.push(v);
 256                 }
 257                 Object ret = null;
 258                 if (v == null) throw je("tried to get the null key from " + o);
 259                 if (o == null) throw je("tried to get property \"" + v + "\" from the null object");
 260                 if (o instanceof String || o instanceof Number || o instanceof Boolean) {
 261                     ret = getFromPrimitive(o,v);
 262                     stack.push(ret);
 263                     break;
 264                 } else if (o instanceof JS) {
 265                     Trap t = null;
 266                     if (o instanceof Trap.TrapScope && v.equals("cascade")) {
 267                         t = ((Trap.TrapScope)o).t.next;
 268                         while (t != null && t.f.numFormalArgs != 0) t = t.next;
 269                         if (t == null) { v = ((Trap.TrapScope)o).t.name; o = ((Trap.TrapScope)o).t.trapee; }
 270
 271                     } else if (o instanceof JS) {
 272                         if (o instanceof JSScope) {
 273                             JSScope p = (JSScope)o; // search the scope-path for the trap
 274                             t = p.getTrap(v);
 275                             while (t == null && p.getParentScope() != null) { p = p.getParentScope(); t = p.getTrap(v); }
 276                         } else {
 277                             t = ((JS)o).getTrap(v);
 278                         }
 279
 280                         while (t != null && t.f.numFormalArgs != 0) t = t.next; // get first read trap
 281                         if (t != null) {
 282                             stack.push(new CallMarker(this));
 283                             JSArray args = new JSArray();
 284                             stack.push(args);
 285                         }
 286                     }
 287                     if (t != null) {
 288                         f = t.f;
 289                         scope = new Trap.TrapScope(f.parentScope, t, null);
 290                         ((Trap.TrapScope)scope).cascadeHappened = true;
 291                         pc = -1;
 292                         break;
 293                     }
 294                     ret = ((JS)o).get(v);
 295                     if (ret == JS.METHOD) ret = new Stub((JS)o, v);
 296                     if (pausecount > initialPauseCount) { pc++; return null; }   // we were paused
 297                     stack.push(ret);
 298                     break;
 299                 }
 300                 throw je("tried to get property " + v + " from a " + o.getClass().getName());
 301             }
 302
 303             case CALL: case CALLMETHOD: {
 304                 int numArgs = JS.toInt(arg);
 305                 Object method = null;
 306                 Object ret = null;
 307                 Object object = stack.pop();
 308
 309                 if (op == CALLMETHOD) {
 310                     if (object == JS.METHOD) {
 311                         method = stack.pop();
 312                         object = stack.pop();
 313                     } else if (object == null) {
 314                         Object name = stack.pop();
 315                         stack.pop();
 316                         throw new JSExn("function '"+name+"' not found");
 317                     } else {
 318                         stack.pop();
 319                         stack.pop();
 320                     }
 321                 }
 322                 Object[] rest = numArgs > 3 ? new Object[numArgs - 3] : null;
 323                 for(int i=numArgs - 1; i>2; i--) rest[i-3] = stack.pop();
 324                 Object a2 = numArgs <= 2 ? null : stack.pop();
 325                 Object a1 = numArgs <= 1 ? null : stack.pop();
 326                 Object a0 = numArgs <= 0 ? null : stack.pop();
 327
 328                 if (object instanceof String || object instanceof Number || object instanceof Boolean) {
 329                     ret = callMethodOnPrimitive(object, method, a0, a1, a2, null, numArgs);
 330
 331                 } else if (object instanceof JSFunction) {
 332                     // FIXME: use something similar to call0/call1/call2 here
 333                     JSArray arguments = new JSArray();
 334                     for(int i=0; i<numArgs; i++) arguments.addElement(i==0?a0:i==1?a1:i==2?a2:rest[i-3]);
 335                     stack.push(new CallMarker(this));
 336                     stack.push(arguments);
 337                     f = (JSFunction)object;
 338                     scope = new JSScope(f.parentScope);
 339                     pc = -1;
 340                     break;
 341
 342                 } else if (object instanceof JS) {
 343                     JS c = (JS)object;
 344                     ret = method == null ? c.call(a0, a1, a2, rest, numArgs) : c.callMethod(method, a0, a1, a2, rest, numArgs);
 345
 346                 } else {
 347                     throw new JSExn("can't call a " + object + " @" + pc + "\n" + f.dump());
 348
 349                 }
 350                 if (pausecount > initialPauseCount) { pc++; return null; }
 351                 stack.push(ret);
 352                 break;
 353             }
 354
 355             case THROW: {
 356                 Object o = stack.pop();
 357                 if(o instanceof JSExn) throw (JSExn)o;
 358                 throw new JSExn(o);
 359             }
 360
 361             case ASSIGN_SUB: case ASSIGN_ADD: {
 362                 Object val = stack.pop();
 363                 Object old = stack.pop();
 364                 Object key = stack.pop();
 365                 Object obj = stack.peek();
 366                 if (val instanceof JSFunction && obj instanceof JSScope) {
 367                     JSScope parent = (JSScope)obj;
 368                     while(parent.getParentScope() != null) parent = parent.getParentScope();
 369                     if (parent instanceof JS) {
 370                         JS b = (JS)parent;
 371                         if (op == ASSIGN_ADD) b.addTrap(key, (JSFunction)val);
 372                         else b.delTrap(key, (JSFunction)val);
 373                         // skip over the "normal" implementation of +=/-=
 374                         pc += ((Integer)arg).intValue() - 1;
 375                         break;
 376                     }
 377                 }
 378                 // use the "normal" implementation
 379                 stack.push(key);
 380                 stack.push(old);
 381                 stack.push(val);
 382                 break;
 383             }
 384
 385             case ADD: {
 386                 int count = ((Number)arg).intValue();
 387                 if(count < 2) throw new Error("this should never happen");
 388                 if(count == 2) {
 389                     // common case
 390                     Object right = stack.pop();
 391                     Object left = stack.pop();
 392                     if(left instanceof String || right instanceof String)
 393                         stack.push(JS.toString(left).concat(JS.toString(right)));
 394                     else stack.push(JS.N(JS.toDouble(left) + JS.toDouble(right)));
 395                 } else {
 396                     Object[] args = new Object[count];
 397                     while(--count >= 0) args[count] = stack.pop();
 398                     if(args[0] instanceof String) {
 399                         StringBuffer sb = new StringBuffer(64);
 400                         for(int i=0;i<args.length;i++) sb.append(JS.toString(args[i]));
 401                         stack.push(sb.toString());
 402                     } else {
 403                         int numStrings = 0;
 404                         for(int i=0;i<args.length;i++) if(args[i] instanceof String) numStrings++;
 405                         if(numStrings == 0) {
 406                             double d = 0.0;
 407                             for(int i=0;i<args.length;i++) d += JS.toDouble(args[i]);
 408                             stack.push(JS.N(d));
 409                         } else {
 410                             int i=0;
 411                             StringBuffer sb = new StringBuffer(64);
 412                             if(!(args[0] instanceof String || args[1] instanceof String)) {
 413                                 double d=0.0;
 414                                 do {
 415                                     d += JS.toDouble(args[i++]);
 416                                 } while(!(args[i] instanceof String));
 417                                 sb.append(JS.toString(JS.N(d)));
 418                             }
 419                             while(i < args.length) sb.append(JS.toString(args[i++]));
 420                             stack.push(sb.toString());
 421                         }
 422                     }
 423                 }
 424                 break;
 425             }
 426
 427             default: {
 428                 Object right = stack.pop();
 429                 Object left = stack.pop();
 430                 switch(op) {
 431
 432                 case BITOR: stack.push(JS.N(JS.toLong(left) | JS.toLong(right))); break;
 433                 case BITXOR: stack.push(JS.N(JS.toLong(left) ^ JS.toLong(right))); break;
 434                 case BITAND: stack.push(JS.N(JS.toLong(left) & JS.toLong(right))); break;
 435
 436                 case SUB: stack.push(JS.N(JS.toDouble(left) - JS.toDouble(right))); break;
 437                 case MUL: stack.push(JS.N(JS.toDouble(left) * JS.toDouble(right))); break;
 438                 case DIV: stack.push(JS.N(JS.toDouble(left) / JS.toDouble(right))); break;
 439                 case MOD: stack.push(JS.N(JS.toDouble(left) % JS.toDouble(right))); break;
 440
 441                 case LSH: stack.push(JS.N(JS.toLong(left) << JS.toLong(right))); break;
 442                 case RSH: stack.push(JS.N(JS.toLong(left) >> JS.toLong(right))); break;
 443                 case URSH: stack.push(JS.N(JS.toLong(left) >>> JS.toLong(right))); break;
 444
 445                 case LT: case LE: case GT: case GE: {
 446                     if (left == null) left = JS.N(0);
 447                     if (right == null) right = JS.N(0);
 448                     int result = 0;
 449                     if (left instanceof String || right instanceof String) {
 450                         result = left.toString().compareTo(right.toString());
 451                     } else {
 452                         result = (int)java.lang.Math.ceil(JS.toDouble(left) - JS.toDouble(right));
 453                     }
 454                     stack.push(JS.B((op == LT && result < 0) || (op == LE && result <= 0) ||
 455                                (op == GT && result > 0) || (op == GE && result >= 0)));
 456                     break;
 457                 }
 458
 459                 case EQ:
 460                 case NE: {
 461                     Object l = left;
 462                     Object r = right;
 463                     boolean ret;
 464                     if (l == null) { Object tmp = r; r = l; l = tmp; }
 465                     if (l == null && r == null) ret = true;
 466                     else if (r == null) ret = false; // l != null, so its false
 467                     else if (l instanceof Boolean) ret = JS.B(JS.toBoolean(r)).equals(l);
 468                     else if (l instanceof Number) ret = JS.toNumber(r).doubleValue() == JS.toNumber(l).doubleValue();
 469                     else if (l instanceof String) ret = r != null && l.equals(r.toString());
 470                     else ret = l.equals(r);
 471                     stack.push(JS.B(op == EQ ? ret : !ret)); break;
 472                 }
 473
 474                 default: throw new Error("unknown opcode " + op);
 475                 } }
 476             }
 477
 478         } catch(JSExn e) {
 479             while(stack.size() > 0) {
 480                 Object o = stack.pop();
 481                 if (o instanceof CatchMarker || o instanceof TryMarker) {
 482                     boolean inCatch = o instanceof CatchMarker;
 483                     if(inCatch) {
 484                         o = stack.pop();
 485                         if(((TryMarker)o).finallyLoc < 0) continue; // no finally block, keep going
 486                     }
 487                     if(!inCatch && ((TryMarker)o).catchLoc >= 0) {
 488                         // run the catch block, this will implicitly run the finally block, if it exists
 489                         stack.push(o);
 490                         stack.push(catchMarker);
 491                         stack.push(e.getObject());
 492                         scope = ((TryMarker)o).scope;
 493                         pc = ((TryMarker)o).catchLoc - 1;
 494                         continue OUTER;
 495                     } else {
 496                         stack.push(e);
 497                         stack.push(new FinallyData(THROW));
 498                         scope = ((TryMarker)o).scope;
 499                         pc = ((TryMarker)o).finallyLoc - 1;
 500                         continue OUTER;
 501                     }
 502                 }
 503                 // no handler found within this func
 504                 if(o instanceof CallMarker) throw e;
 505             }
 506             throw e;
 507         } // end try/catch
 508         } // end for
 509     }
 510
 511
 512
 513     // Markers //////////////////////////////////////////////////////////////////////
 514
 515     public static class CallMarker {
 516         int pc;
 517         JSScope scope;
 518         JSFunction f;
 519         public CallMarker(Interpreter cx) { pc = cx.pc + 1; scope = cx.scope; f = cx.f; }
 520     }
 521
 522     public static class CatchMarker { public CatchMarker() { } }
 523     private static CatchMarker catchMarker = new CatchMarker();
 524
 525     public static class LoopMarker {
 526         public int location;
 527         public String label;
 528         public JSScope scope;
 529         public LoopMarker(int location, String label, JSScope scope) {
 530             this.location = location;
 531             this.label = label;
 532             this.scope = scope;
 533         }
 534     }
 535     public static class TryMarker {
 536         public int catchLoc;
 537         public int finallyLoc;
 538         public JSScope scope;
 539         public TryMarker(int catchLoc, int finallyLoc, JSScope scope) {
 540             this.catchLoc = catchLoc;
 541             this.finallyLoc = finallyLoc;
 542             this.scope = scope;
 543         }
 544     }
 545     public static class FinallyData {
 546         public int op;
 547         public Object arg;
 548         public FinallyData(int op, Object arg) { this.op = op; this.arg = arg; }
 549         public FinallyData(int op) { this(op,null); }
 550     }
 551
 552
 553     // Operations on Primitives //////////////////////////////////////////////////////////////////////
 554
 555     static Object callMethodOnPrimitive(Object o, Object method, Object arg0, Object arg1, Object arg2, Object[] rest, int alength) throws JSExn {
 556         if (method == null || !(method instanceof String) || "".equals(method))
 557             throw new JSExn("attempt to call a non-existant method on a primitive");
 558
 559         if (o instanceof Number) {
 560             //#switch(method)
 561             case "toFixed": throw new JSExn("toFixed() not implemented");
 562             case "toExponential": throw new JSExn("toExponential() not implemented");
 563             case "toPrecision": throw new JSExn("toPrecision() not implemented");
 564             case "toString": {
 565                 int radix = alength >= 1 ? JS.toInt(arg0) : 10;
 566                 return Long.toString(((Number)o).longValue(),radix);
 567             }
 568             //#end
 569         } else if (o instanceof Boolean) {
 570             // No methods for Booleans
 571             throw new JSExn("attempt to call a method on a Boolean");
 572         }
 573
 574         String s = JS.toString(o);
 575         int slength = s.length();
 576         //#switch(method)
 577         case "substring": {
 578             int a = alength >= 1 ? JS.toInt(arg0) : 0;
 579             int b = alength >= 2 ? JS.toInt(arg1) : slength;
 580             if (a > slength) a = slength;
 581             if (b > slength) b = slength;
 582             if (a < 0) a = 0;
 583             if (b < 0) b = 0;
 584             if (a > b) { int tmp = a; a = b; b = tmp; }
 585             return s.substring(a,b);
 586         }
 587         case "substr": {
 588             int start = alength >= 1 ? JS.toInt(arg0) : 0;
 589             int len = alength >= 2 ? JS.toInt(arg1) : Integer.MAX_VALUE;
 590             if (start < 0) start = slength + start;
 591             if (start < 0) start = 0;
 592             if (len < 0) len = 0;
 593             if (len > slength - start) len = slength - start;
 594             if (len <= 0) return "";
 595             return s.substring(start,start+len);
 596         }
 597         case "charAt": {
 598             int p = alength >= 1 ? JS.toInt(arg0) : 0;
 599             if (p < 0 || p >= slength) return "";
 600             return s.substring(p,p+1);
 601         }
 602         case "charCodeAt": {
 603             int p = alength >= 1 ? JS.toInt(arg0) : 0;
 604             if (p < 0 || p >= slength) return JS.N(Double.NaN);
 605             return JS.N(s.charAt(p));
 606         }
 607         case "concat": {
 608             StringBuffer sb = new StringBuffer(slength*2).append(s);
 609             for(int i=0;i<alength;i++) sb.append(i==0?arg0:i==1?arg1:i==2?arg2:rest[i-3]);
 610             return sb.toString();
 611         }
 612         case "indexOf": {
 613             String search = alength >= 1 ? arg0.toString() : "null";
 614             int start = alength >= 2 ? JS.toInt(arg1) : 0;
 615             // Java's indexOf handles an out of bounds start index, it'll return -1
 616             return JS.N(s.indexOf(search,start));
 617         }
 618         case "lastIndexOf": {
 619             String search = alength >= 1 ? arg0.toString() : "null";
 620             int start = alength >= 2 ? JS.toInt(arg1) : 0;
 621             // Java's indexOf handles an out of bounds start index, it'll return -1
 622             return JS.N(s.lastIndexOf(search,start));
 623         }
 624         case "match": return JSRegexp.stringMatch(s,arg0);
 625         case "replace": return JSRegexp.stringReplace(s,(String)arg0,arg1);
 626         case "search": return JSRegexp.stringSearch(s,arg0);
 627         case "split": return JSRegexp.stringSplit(s,arg0,arg1,alength);
 628         case "toLowerCase": return s.toLowerCase();
 629         case "toUpperCase": return s.toUpperCase();
 630         case "toString": return s;
 631         case "slice": {
 632             int a = alength >= 1 ? JS.toInt(arg0) : 0;
 633             int b = alength >= 2 ? JS.toInt(arg1) : slength;
 634             if (a < 0) a = slength + a;
 635             if (b < 0) b = slength + b;
 636             if (a < 0) a = 0;
 637             if (b < 0) b = 0;
 638             if (a > slength) a = slength;
 639             if (b > slength) b = slength;
 640             if (a > b) return "";
 641             return s.substring(a,b);
 642         }
 643         //#end
 644         throw new JSExn("Attempted to call non-existent method: " + method);
 645     }
 646
 647     static Object getFromPrimitive(Object o, Object key) throws JSExn {
 648         boolean returnJS = false;
 649         if (o instanceof Boolean) {
 650             throw new JSExn("cannot call methods on Booleans");
 651         } else if (o instanceof Number) {
 652             if (key.equals("toPrecision") || key.equals("toExponential") || key.equals("toFixed"))
 653                 returnJS = true;
 654         }
 655         if (!returnJS) {
 656             // the string stuff applies to everything
 657             String s = o.toString();
 658
 659             // this is sort of ugly, but this list should never change
 660             // These should provide a complete (enough) implementation of the ECMA-262 String object
 661
 662             //#switch(key)
 663             case "length": return JS.N(s.length());
 664             case "substring": returnJS = true; break;
 665             case "charAt": returnJS = true; break;
 666             case "charCodeAt": returnJS = true; break;
 667             case "concat": returnJS = true; break;
 668             case "indexOf": returnJS = true; break;
 669             case "lastIndexOf": returnJS = true; break;
 670             case "match": returnJS = true; break;
 671             case "replace": returnJS = true; break;
 672             case "seatch": returnJS = true; break;
 673             case "slice": returnJS = true; break;
 674             case "split": returnJS = true; break;
 675             case "toLowerCase": returnJS = true; break;
 676             case "toUpperCase": returnJS = true; break;
 677             case "toString": returnJS = true; break;
 678             case "substr": returnJS = true; break;
 679            //#end
 680         }
 681         if (returnJS) {
 682             final Object target = o;
 683             final String method = key.toString();
 684             return new JS() {
 685                     public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
 686                         if (nargs > 2) throw new JSExn("cannot call that method with that many arguments");
 687                         return callMethodOnPrimitive(target, method, a0, a1, a2, rest, nargs);
 688                     }
 689             };
 690         }
 691         return null;
 692     }
 693
 694     private static class Stub extends JS {
 695         private Object method;
 696         JS obj;
 697         public Stub(JS obj, Object method) { this.obj = obj; this.method = method; }
 698         public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
 699             return ((JS)obj).callMethod(method, a0, a1, a2, rest, nargs);
 700         }
 701     }
 702 }