src/org/ibex/js/Interpreter.java

   1 // Copyright 2004 Adam Megacz, see the COPYING file for licensing [GPL]
   2 package org.ibex.js;
   3
   4 import org.ibex.util.*;
   5 import java.util.*;
   6
   7 /** Encapsulates a single JS interpreter (ie call stack) */
   8 class Interpreter implements ByteCodes, Tokens {
   9     private static final int MAX_STACK_SIZE = 512;
  10
  11     // Thread-Interpreter Mapping /////////////////////////////////////////////////////////////////////////
  12
  13     static Interpreter current() { return (Interpreter)threadToInterpreter.get(Thread.currentThread()); }
  14     private static Hashtable threadToInterpreter = new Hashtable();
  15
  16
  17     // Instance members and methods //////////////////////////////////////////////////////////////////////
  18
  19     int pausecount;               ///< the number of times pause() has been invoked; -1 indicates unpauseable
  20     JSFunction f = null;          ///< the currently-executing JSFunction
  21     JSScope scope;                ///< the current top-level scope (LIFO stack via NEWSCOPE/OLDSCOPE)
  22     Vec stack = new Vec();        ///< the object stack
  23     int pc = 0;                   ///< the program counter
  24
  25     Interpreter(JSFunction f, boolean pauseable, JSArray args) {
  26         stack.push(new Interpreter.CallMarker(this));    // the "root function returned" marker -- f==null
  27         this.f = f;
  28         this.pausecount = pauseable ? 0 : -1;
  29         this.scope = new JSScope(f.parentScope);
  30         stack.push(args);
  31     }
  32
  33     /** this is the only synchronization point we need in order to be threadsafe */
  34     synchronized Object resume() throws JSExn {
  35         Thread t = Thread.currentThread();
  36         Interpreter old = (Interpreter)threadToInterpreter.get(t);
  37         threadToInterpreter.put(t, this);
  38         try {
  39             return run();
  40         } finally {
  41             if (old == null) threadToInterpreter.remove(t);
  42             else threadToInterpreter.put(t, old);
  43         }
  44     }
  45
  46     static int getLine() {
  47         Interpreter c = Interpreter.current();
  48         return c == null || c.f == null || c.pc < 0 || c.pc >= c.f.size ? -1 : c.f.line[c.pc];
  49     }
  50
  51     static String getSourceName() {
  52         Interpreter c = Interpreter.current();
  53         return c == null || c.f == null ? null : c.f.sourceName;
  54     }
  55
  56     private static JSExn je(String s) { return new JSExn(getSourceName() + ":" + getLine() + " " + s); }
  57
  58     // FIXME: double check the trap logic
  59     private Object run() throws JSExn {
  60
  61         // if pausecount changes after a get/put/call, we know we've been paused
  62         final int initialPauseCount = pausecount;
  63
  64         OUTER: for(;; pc++) {
  65         try {
  66             if (f == null) return stack.pop();
  67             int op = f.op[pc];
  68             Object arg = f.arg[pc];
  69             if(op == FINALLY_DONE) {
  70                 FinallyData fd = (FinallyData) stack.pop();
  71                 if(fd == null) continue OUTER; // NOP
  72                 if(fd.exn != null) throw fd.exn;
  73                 op = fd.op;
  74                 arg = fd.arg;
  75             }
  76             switch(op) {
  77             case LITERAL: stack.push(arg); break;
  78             case OBJECT: stack.push(new JS()); break;
  79             case ARRAY: stack.push(new JSArray(JS.toNumber(arg).intValue())); break;
  80             case DECLARE: scope.declare((String)(arg==null ? stack.peek() : arg)); if(arg != null) stack.push(arg); break;
  81             case TOPSCOPE: stack.push(scope); break;
  82             case JT: if (JS.toBoolean(stack.pop())) pc += JS.toNumber(arg).intValue() - 1; break;
  83             case JF: if (!JS.toBoolean(stack.pop())) pc += JS.toNumber(arg).intValue() - 1; break;
  84             case JMP: pc += JS.toNumber(arg).intValue() - 1; break;
  85             case POP: stack.pop(); break;
  86             case SWAP: {
  87                 int depth = (arg == null ? 1 : JS.toInt(arg));
  88                 Object save = stack.elementAt(stack.size() - 1);
  89                 for(int i=stack.size() - 1; i > stack.size() - 1 - depth; i--)
  90                     stack.setElementAt(stack.elementAt(i-1), i);
  91                 stack.setElementAt(save, stack.size() - depth - 1);
  92                 break; }
  93             case DUP: stack.push(stack.peek()); break;
  94             case NEWSCOPE: scope = new JSScope(scope); break;
  95             case OLDSCOPE: scope = scope.getParentScope(); break;
  96             case ASSERT:
  97                 if (JS.checkAssertions && !JS.toBoolean(stack.pop()))
  98                     throw je("ibex.assertion.failed" /*FEATURE: line number*/); break;
  99             case BITNOT: stack.push(JS.N(~JS.toLong(stack.pop()))); break;
 100             case BANG: stack.push(JS.B(!JS.toBoolean(stack.pop()))); break;
 101             case NEWFUNCTION: stack.push(((JSFunction)arg)._cloneWithNewParentScope(scope)); break;
 102             case LABEL: break;
 103
 104             case TYPEOF: {
 105                 Object o = stack.pop();
 106                 if (o == null) stack.push(null);
 107                 else if (o instanceof JS) stack.push("object");
 108                 else if (o instanceof String) stack.push("string");
 109                 else if (o instanceof Number) stack.push("number");
 110                 else if (o instanceof Boolean) stack.push("boolean");
 111                 else throw new Error("this should not happen");
 112                 break;
 113             }
 114
 115             case PUSHKEYS: {
 116                 Object o = stack.peek();
 117                 Enumeration e = ((JS)o).keys();
 118                 JSArray a = new JSArray();
 119                 while(e.hasMoreElements()) a.addElement(e.nextElement());
 120                 stack.push(a);
 121                 break;
 122             }
 123
 124             case LOOP:
 125                 stack.push(new LoopMarker(pc, pc > 0 && f.op[pc - 1] == LABEL ? (String)f.arg[pc - 1] : (String)null, scope));
 126                 stack.push(Boolean.TRUE);
 127                 break;
 128
 129             case BREAK:
 130             case CONTINUE:
 131                 while(stack.size() > 0) {
 132                     Object o = stack.pop();
 133                     if (o instanceof CallMarker) je("break or continue not within a loop");
 134                     if (o instanceof TryMarker) {
 135                         if(((TryMarker)o).finallyLoc < 0) continue; // no finally block, keep going
 136                         stack.push(new FinallyData(op, arg));
 137                         scope = ((TryMarker)o).scope;
 138                         pc = ((TryMarker)o).finallyLoc - 1;
 139                         continue OUTER;
 140                     }
 141                     if (o instanceof LoopMarker) {
 142                         if (arg == null || arg.equals(((LoopMarker)o).label)) {
 143                             int loopInstructionLocation = ((LoopMarker)o).location;
 144                             int endOfLoop = ((Integer)f.arg[loopInstructionLocation]).intValue() + loopInstructionLocation;
 145                             scope = ((LoopMarker)o).scope;
 146                             if (op == CONTINUE) { stack.push(o); stack.push(Boolean.FALSE); }
 147                             pc = op == BREAK ? endOfLoop - 1 : loopInstructionLocation;
 148                             continue OUTER;
 149                         }
 150                     }
 151                 }
 152                 throw new Error("CONTINUE/BREAK invoked but couldn't find LoopMarker at " +
 153                                 getSourceName() + ":" + getLine());
 154
 155             case TRY: {
 156                 int[] jmps = (int[]) arg;
 157                 // jmps[0] is how far away the catch block is, jmps[1] is how far away the finally block is
 158                 // each can be < 0 if the specified block does not exist
 159                 stack.push(new TryMarker(jmps[0] < 0 ? -1 : pc + jmps[0], jmps[1] < 0 ? -1 : pc + jmps[1], this));
 160                 break;
 161             }
 162
 163             case RETURN: {
 164                 Object retval = stack.pop();
 165                 while(stack.size() > 0) {
 166                     Object o = stack.pop();
 167                     if (o instanceof TryMarker) {
 168                         if(((TryMarker)o).finallyLoc < 0) continue;
 169                         stack.push(retval);
 170                         stack.push(new FinallyData(RETURN));
 171                         scope = ((TryMarker)o).scope;
 172                         pc = ((TryMarker)o).finallyLoc - 1;
 173                         continue OUTER;
 174                     } else if (o instanceof CallMarker) {
 175                         if (o instanceof TrapMarker) { // handles return component of a read trap
 176                             TrapMarker tm = (TrapMarker) o;
 177                             boolean cascade = tm.t.writeTrap() && !tm.cascadeHappened && !JS.toBoolean(retval);
 178                             if(cascade) {
 179                                 Trap t = tm.t.next;
 180                                 while(t != null && t.readTrap()) t = t.next;
 181                                 if(t != null) {
 182                                     tm.t = t;
 183                                     stack.push(tm);
 184                                     JSArray args = new JSArray();
 185                                     args.addElement(tm.val);
 186                                     stack.push(args);
 187                                     f = t.f;
 188                                     scope = new JSScope(f.parentScope);
 189                                     pc = -1;
 190                                     continue OUTER;
 191                                 } else {
 192                                     tm.trapee.put(tm.key,tm.val);
 193                                 }
 194                             }
 195                         }
 196                         scope = ((CallMarker)o).scope;
 197                         pc = ((CallMarker)o).pc - 1;
 198                         f = (JSFunction)((CallMarker)o).f;
 199                         stack.push(retval);
 200                         if (pausecount > initialPauseCount) { pc++; return null; }   // we were paused
 201                         continue OUTER;
 202                     }
 203                 }
 204                 throw new Error("error: RETURN invoked but couldn't find a CallMarker!");
 205             }
 206
 207             case PUT: {
 208                 Object val = stack.pop();
 209                 Object key = stack.pop();
 210                 Object target = stack.peek();
 211                 if (target == null)
 212                     throw je("tried to put a value to the " + key + " property on the null value");
 213                 if (!(target instanceof JS))
 214                     throw je("tried to put a value to the " + key + " property on a " + target.getClass().getName());
 215                 if (key == null)
 216                     throw je("tried to assign \"" + (val==null?"(null)":val.toString()) + "\" to the null key");
 217
 218                 if (target instanceof String || target instanceof Number || target instanceof Boolean) throw new JSExn("can't put values to primitives");
 219                 if(!(target instanceof JS)) throw new Error("should never happen");
 220
 221                 Trap t = null;
 222                 TrapMarker tm = null;
 223                 if(target instanceof JSScope && key.equals("cascade")) {
 224                     Object o=null;
 225                     int i;
 226                     for(i=stack.size()-1;i>=0;i--) if((o = stack.elementAt(i)) instanceof CallMarker) break;
 227                     if(i==0) throw new Error("didn't find a call marker while doing cascade");
 228                     if(o instanceof TrapMarker) {
 229                         tm = (TrapMarker) o;
 230                         target = tm.trapee;
 231                         key = tm.key;
 232                         tm.cascadeHappened = true;
 233                         t = tm.t;
 234                         if(t.readTrap()) throw new JSExn("can't put to cascade in a read trap");
 235                         t = t.next;
 236                         while(t != null && t.readTrap()) t = t.next;
 237                     }
 238                 }
 239                 if(tm == null) { // didn't find a trap marker, try to find a trap
 240                     t = target instanceof JSScope ? t = ((JSScope)target).top().getTrap(key) : ((JS)target).getTrap(key);
 241                     while(t != null && t.readTrap()) t = t.next;
 242                 }
 243
 244                 stack.push(val);
 245
 246                 if(t != null) {
 247                     stack.push(new TrapMarker(this,t,(JS)target,key,val));
 248                     JSArray args = new JSArray();
 249                     args.addElement(val);
 250                     stack.push(args);
 251                     f = t.f;
 252                     scope = new JSScope(f.parentScope);
 253                     pc = -1;
 254                     break;
 255                 } else {
 256                     ((JS)target).put(key,val);
 257                     if (pausecount > initialPauseCount) { pc++; return null; }   // we were paused
 258                     break;
 259                 }
 260             }
 261
 262             case GET:
 263             case GET_PRESERVE: {
 264                 Object target, key;
 265                 if (op == GET) {
 266                     key = arg == null ? stack.pop() : arg;
 267                     target = stack.pop();
 268                 } else {
 269                     key = stack.pop();
 270                     target = stack.peek();
 271                     stack.push(key);
 272                 }
 273                 Object ret = null;
 274                 if (key == null) throw je("tried to get the null key from " + target);
 275                 if (target == null) throw je("tried to get property \"" + key + "\" from the null object");
 276                 if (target instanceof String || target instanceof Number || target instanceof Boolean) {
 277                     ret = getFromPrimitive(target,key);
 278                     stack.push(ret);
 279                     break;
 280                 }
 281                 if(!(target instanceof JS)) throw new Error("should never happen");
 282
 283                 Trap t = null;
 284                 TrapMarker tm = null;
 285                 if(target instanceof JSScope && key.equals("cascade")) {
 286                     Object o=null;
 287                     int i;
 288                     for(i=stack.size()-1;i>=0;i--) if((o = stack.elementAt(i)) instanceof CallMarker) break;
 289                     if(i==0) throw new Error("didn't find a call marker while doing cascade");
 290                     if(o instanceof TrapMarker) {
 291                         tm = (TrapMarker) o;
 292                         target = tm.trapee;
 293                         key = tm.key;
 294                         t = tm.t;
 295                         if(t.writeTrap()) throw new JSExn("can't do a write cascade in a read trap");
 296                         t = t.next;
 297                         while(t != null && t.writeTrap()) t = t.next;
 298                         if(t != null) tm.cascadeHappened = true;
 299                     }
 300                 }
 301                 if(tm == null) { // didn't find a trap marker, try to find a trap
 302                     t = target instanceof JSScope ? t = ((JSScope)target).top().getTrap(key) : ((JS)target).getTrap(key);
 303                     while(t != null && t.writeTrap()) t = t.next;
 304                 }
 305
 306                 if(t != null) {
 307                     stack.push(new TrapMarker(this,t,(JS)target,key,null));
 308                     stack.push(new JSArray());
 309                     f = t.f;
 310                     scope = new JSScope(f.parentScope);
 311                     pc = -1;
 312                     break;
 313                 } else {
 314                     ret = ((JS)target).get(key);
 315                     if (ret == JS.METHOD) ret = new Stub((JS)target, key);
 316                     stack.push(ret);
 317                     if (pausecount > initialPauseCount) { pc++; return null; }   // we were paused
 318                     break;
 319                 }
 320             }
 321
 322             case CALL: case CALLMETHOD: {
 323                 int numArgs = JS.toInt(arg);
 324                 Object method = null;
 325                 Object ret = null;
 326                 Object object = stack.pop();
 327
 328                 if (op == CALLMETHOD) {
 329                     if (object == JS.METHOD) {
 330                         method = stack.pop();
 331                         object = stack.pop();
 332                     } else if (object == null) {
 333                         Object name = stack.pop();
 334                         stack.pop();
 335                         throw new JSExn("function '"+name+"' not found");
 336                     } else {
 337                         stack.pop();
 338                         stack.pop();
 339                     }
 340                 }
 341                 Object[] rest = numArgs > 3 ? new Object[numArgs - 3] : null;
 342                 for(int i=numArgs - 1; i>2; i--) rest[i-3] = stack.pop();
 343                 Object a2 = numArgs <= 2 ? null : stack.pop();
 344                 Object a1 = numArgs <= 1 ? null : stack.pop();
 345                 Object a0 = numArgs <= 0 ? null : stack.pop();
 346
 347                 if (object instanceof String || object instanceof Number || object instanceof Boolean) {
 348                     ret = callMethodOnPrimitive(object, method, a0, a1, a2, null, numArgs);
 349
 350                 } else if (object instanceof JSFunction) {
 351                     // FIXME: use something similar to call0/call1/call2 here
 352                     JSArray arguments = new JSArray();
 353                     for(int i=0; i<numArgs; i++) arguments.addElement(i==0?a0:i==1?a1:i==2?a2:rest[i-3]);
 354                     stack.push(new CallMarker(this));
 355                     if(stack.size() > MAX_STACK_SIZE) throw new JSExn("stack overflow");
 356                     stack.push(arguments);
 357                     f = (JSFunction)object;
 358                     scope = new JSScope(f.parentScope);
 359                     pc = -1;
 360                     break;
 361
 362                 } else if (object instanceof JS) {
 363                     JS c = (JS)object;
 364                     ret = method == null ? c.call(a0, a1, a2, rest, numArgs) : c.callMethod(method, a0, a1, a2, rest, numArgs);
 365
 366                 } else {
 367                     throw new JSExn("can't call a " + object + " @" + pc + "\n" + f.dump());
 368
 369                 }
 370                 if (pausecount > initialPauseCount) { pc++; return null; }
 371                 stack.push(ret);
 372                 break;
 373             }
 374
 375             case THROW:
 376                 throw new JSExn(stack.pop(), stack, f, pc, scope);
 377
 378                 /* FIXME
 379             case MAKE_GRAMMAR: {
 380                 final Grammar r = (Grammar)arg;
 381                 final JSScope final_scope = scope;
 382                 Grammar r2 = new Grammar() {
 383                         public int match(String s, int start, Hash v, JSScope scope) throws JSExn {
 384                             return r.match(s, start, v, final_scope);
 385                         }
 386                         public int matchAndWrite(String s, int start, Hash v, JSScope scope, String key) throws JSExn {
 387                             return r.matchAndWrite(s, start, v, final_scope, key);
 388                         }
 389                         public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
 390                             Hash v = new Hash();
 391                             r.matchAndWrite((String)a0, 0, v, final_scope, "foo");
 392                             return v.get("foo");
 393                         }
 394                     };
 395                 Object obj = stack.pop();
 396                 if (obj != null && obj instanceof Grammar) r2 = new Grammar.Alternative((Grammar)obj, r2);
 397                 stack.push(r2);
 398                 break;
 399             }
 400                 */
 401             case ADD_TRAP: case DEL_TRAP: {
 402                 Object val = stack.pop();
 403                 Object key = stack.pop();
 404                 Object obj = stack.peek();
 405                 // A trap addition/removal
 406                 JS js = (JS) obj;
 407                 if(js instanceof JSScope) {
 408                     JSScope s = (JSScope) js;
 409                     while(s.getParentScope() != null) {
 410                         if(s.has(key)) throw new JSExn("cannot trap a variable that isn't at the top level scope");
 411                         s = s.getParentScope();
 412                     }
 413                     js = s;
 414                 }
 415                 // might want this?
 416                 // if(!js.has(key)) throw new JSExn("tried to add/remove a trap from an uninitialized variable");
 417                 if(op == ADD_TRAP) js.addTrap(key, (JSFunction)val);
 418                 else js.delTrap(key, (JSFunction)val);
 419                 break;
 420             }
 421
 422             case ASSIGN_SUB: case ASSIGN_ADD: {
 423                 Object val = stack.pop();
 424                 Object key = stack.pop();
 425                 Object obj = stack.peek();
 426                 // The following setup is VERY important. The generated bytecode depends on the stack
 427                 // being setup like this (top to bottom) KEY, OBJ, VAL, KEY, OBJ
 428                 stack.push(key);
 429                 stack.push(val);
 430                 stack.push(obj);
 431                 stack.push(key);
 432                 break;
 433             }
 434
 435             case ADD: {
 436                 int count = ((Number)arg).intValue();
 437                 if(count < 2) throw new Error("this should never happen");
 438                 if(count == 2) {
 439                     // common case
 440                     Object right = stack.pop();
 441                     Object left = stack.pop();
 442                     if(left instanceof String || right instanceof String)
 443                         stack.push(JS.toString(left).concat(JS.toString(right)));
 444                     else stack.push(JS.N(JS.toDouble(left) + JS.toDouble(right)));
 445                 } else {
 446                     Object[] args = new Object[count];
 447                     while(--count >= 0) args[count] = stack.pop();
 448                     if(args[0] instanceof String) {
 449                         StringBuffer sb = new StringBuffer(64);
 450                         for(int i=0;i<args.length;i++) sb.append(JS.toString(args[i]));
 451                         stack.push(sb.toString());
 452                     } else {
 453                         int numStrings = 0;
 454                         for(int i=0;i<args.length;i++) if(args[i] instanceof String) numStrings++;
 455                         if(numStrings == 0) {
 456                             double d = 0.0;
 457                             for(int i=0;i<args.length;i++) d += JS.toDouble(args[i]);
 458                             stack.push(JS.N(d));
 459                         } else {
 460                             int i=0;
 461                             StringBuffer sb = new StringBuffer(64);
 462                             if(!(args[0] instanceof String || args[1] instanceof String)) {
 463                                 double d=0.0;
 464                                 do {
 465                                     d += JS.toDouble(args[i++]);
 466                                 } while(!(args[i] instanceof String));
 467                                 sb.append(JS.toString(JS.N(d)));
 468                             }
 469                             while(i < args.length) sb.append(JS.toString(args[i++]));
 470                             stack.push(sb.toString());
 471                         }
 472                     }
 473                 }
 474                 break;
 475             }
 476
 477             default: {
 478                 if(op == BITOR) throw new Error("pc: " + pc + " of " + f);
 479                 Object right = stack.pop();
 480                 Object left = stack.pop();
 481                 switch(op) {
 482
 483                 case BITOR: stack.push(JS.N(JS.toLong(left) | JS.toLong(right))); break;
 484                 case BITXOR: stack.push(JS.N(JS.toLong(left) ^ JS.toLong(right))); break;
 485                 case BITAND: stack.push(JS.N(JS.toLong(left) & JS.toLong(right))); break;
 486
 487                 case SUB: stack.push(JS.N(JS.toDouble(left) - JS.toDouble(right))); break;
 488                 case MUL: stack.push(JS.N(JS.toDouble(left) * JS.toDouble(right))); break;
 489                 case DIV: stack.push(JS.N(JS.toDouble(left) / JS.toDouble(right))); break;
 490                 case MOD: stack.push(JS.N(JS.toDouble(left) % JS.toDouble(right))); break;
 491
 492                 case LSH: stack.push(JS.N(JS.toLong(left) << JS.toLong(right))); break;
 493                 case RSH: stack.push(JS.N(JS.toLong(left) >> JS.toLong(right))); break;
 494                 case URSH: stack.push(JS.N(JS.toLong(left) >>> JS.toLong(right))); break;
 495
 496                 case LT: case LE: case GT: case GE: {
 497                     if (left == null) left = JS.N(0);
 498                     if (right == null) right = JS.N(0);
 499                     int result = 0;
 500                     if (left instanceof String || right instanceof String) {
 501                         result = JS.toString(left).compareTo(JS.toString(right));
 502                     } else {
 503                         result = (int)java.lang.Math.ceil(JS.toDouble(left) - JS.toDouble(right));
 504                     }
 505                     stack.push(JS.B((op == LT && result < 0) || (op == LE && result <= 0) ||
 506                                (op == GT && result > 0) || (op == GE && result >= 0)));
 507                     break;
 508                 }
 509
 510                 case EQ:
 511                 case NE: {
 512                     // FIXME: This is not correct, see ECMA-262 11.9.3
 513                     Object l = left;
 514                     Object r = right;
 515                     boolean ret;
 516                     if (l == null) { Object tmp = r; r = l; l = tmp; }
 517                     if (l == null && r == null) ret = true;
 518                     else if (r == null) ret = false; // l != null, so its false
 519                     else if (l instanceof Boolean) ret = JS.B(JS.toBoolean(r)).equals(l);
 520                     else if (l instanceof Number) ret = JS.toNumber(r).doubleValue() == JS.toNumber(l).doubleValue();
 521                     else if (l instanceof String) ret = r != null && l.equals(JS.toString(r));
 522                     else ret = l.equals(r);
 523                     stack.push(JS.B(op == EQ ? ret : !ret)); break;
 524                 }
 525
 526                 default: throw new Error("unknown opcode " + op);
 527                 } }
 528             }
 529
 530         } catch(JSExn e) {
 531             while(stack.size() > 0) {
 532                 Object o = stack.pop();
 533                 if (o instanceof CatchMarker || o instanceof TryMarker) {
 534                     boolean inCatch = o instanceof CatchMarker;
 535                     if(inCatch) {
 536                         o = stack.pop();
 537                         if(((TryMarker)o).finallyLoc < 0) continue; // no finally block, keep going
 538                     }
 539                     if(!inCatch && ((TryMarker)o).catchLoc >= 0) {
 540                         // run the catch block, this will implicitly run the finally block, if it exists
 541                         stack.push(o);
 542                         stack.push(catchMarker);
 543                         stack.push(e.getObject());
 544                         f = ((TryMarker)o).f;
 545                         scope = ((TryMarker)o).scope;
 546                         pc = ((TryMarker)o).catchLoc - 1;
 547                         continue OUTER;
 548                     } else {
 549                         stack.push(new FinallyData(e));
 550                         f = ((TryMarker)o).f;
 551                         scope = ((TryMarker)o).scope;
 552                         pc = ((TryMarker)o).finallyLoc - 1;
 553                         continue OUTER;
 554                     }
 555                 }
 556             }
 557             throw e;
 558         } // end try/catch
 559         } // end for
 560     }
 561
 562
 563
 564     // Markers //////////////////////////////////////////////////////////////////////
 565
 566     public static class CallMarker {
 567         int pc;
 568         JSScope scope;
 569         JSFunction f;
 570         public CallMarker(Interpreter cx) { pc = cx.pc + 1; scope = cx.scope; f = cx.f; }
 571     }
 572
 573     public static class TrapMarker extends CallMarker {
 574         Trap t;
 575         JS trapee;
 576         Object key;
 577         Object val;
 578         boolean cascadeHappened;
 579         public TrapMarker(Interpreter cx, Trap t, JS trapee, Object key, Object val) {
 580             super(cx);
 581             this.t = t;
 582             this.trapee = trapee;
 583             this.key = key;
 584             this.val = val;
 585         }
 586     }
 587
 588     public static class CatchMarker { }
 589     private static CatchMarker catchMarker = new CatchMarker();
 590
 591     public static class LoopMarker {
 592         public int location;
 593         public String label;
 594         public JSScope scope;
 595         public LoopMarker(int location, String label, JSScope scope) {
 596             this.location = location;
 597             this.label = label;
 598             this.scope = scope;
 599         }
 600     }
 601     public static class TryMarker {
 602         public int catchLoc;
 603         public int finallyLoc;
 604         public JSScope scope;
 605         public JSFunction f;
 606         public TryMarker(int catchLoc, int finallyLoc, Interpreter cx) {
 607             this.catchLoc = catchLoc;
 608             this.finallyLoc = finallyLoc;
 609             this.scope = cx.scope;
 610             this.f = cx.f;
 611         }
 612     }
 613     public static class FinallyData {
 614         public int op;
 615         public Object arg;
 616         public JSExn exn;
 617         public FinallyData(int op) { this(op,null); }
 618         public FinallyData(int op, Object arg) { this.op = op; this.arg = arg; }
 619         public FinallyData(JSExn exn) { this.exn = exn; } // Just throw this exn
 620     }
 621
 622
 623     // Operations on Primitives //////////////////////////////////////////////////////////////////////
 624
 625     static Object callMethodOnPrimitive(Object o, Object method, Object arg0, Object arg1, Object arg2, Object[] rest, int alength) throws JSExn {
 626         if (method == null || !(method instanceof String) || "".equals(method))
 627             throw new JSExn("attempt to call a non-existant method on a primitive");
 628
 629         if (o instanceof Number) {
 630             //#switch(method)
 631             case "toFixed": throw new JSExn("toFixed() not implemented");
 632             case "toExponential": throw new JSExn("toExponential() not implemented");
 633             case "toPrecision": throw new JSExn("toPrecision() not implemented");
 634             case "toString": {
 635                 int radix = alength >= 1 ? JS.toInt(arg0) : 10;
 636                 return Long.toString(((Number)o).longValue(),radix);
 637             }
 638             //#end
 639         } else if (o instanceof Boolean) {
 640             // No methods for Booleans
 641             throw new JSExn("attempt to call a method on a Boolean");
 642         }
 643
 644         String s = JS.toString(o);
 645         int slength = s.length();
 646         //#switch(method)
 647         case "substring": {
 648             int a = alength >= 1 ? JS.toInt(arg0) : 0;
 649             int b = alength >= 2 ? JS.toInt(arg1) : slength;
 650             if (a > slength) a = slength;
 651             if (b > slength) b = slength;
 652             if (a < 0) a = 0;
 653             if (b < 0) b = 0;
 654             if (a > b) { int tmp = a; a = b; b = tmp; }
 655             return s.substring(a,b);
 656         }
 657         case "substr": {
 658             int start = alength >= 1 ? JS.toInt(arg0) : 0;
 659             int len = alength >= 2 ? JS.toInt(arg1) : Integer.MAX_VALUE;
 660             if (start < 0) start = slength + start;
 661             if (start < 0) start = 0;
 662             if (len < 0) len = 0;
 663             if (len > slength - start) len = slength - start;
 664             if (len <= 0) return "";
 665             return s.substring(start,start+len);
 666         }
 667         case "charAt": {
 668             int p = alength >= 1 ? JS.toInt(arg0) : 0;
 669             if (p < 0 || p >= slength) return "";
 670             return s.substring(p,p+1);
 671         }
 672         case "charCodeAt": {
 673             int p = alength >= 1 ? JS.toInt(arg0) : 0;
 674             if (p < 0 || p >= slength) return JS.N(Double.NaN);
 675             return JS.N(s.charAt(p));
 676         }
 677         case "concat": {
 678             StringBuffer sb = new StringBuffer(slength*2).append(s);
 679             for(int i=0;i<alength;i++) sb.append(i==0?arg0:i==1?arg1:i==2?arg2:rest[i-3]);
 680             return sb.toString();
 681         }
 682         case "indexOf": {
 683             String search = alength >= 1 ? JS.toString(arg0) : "null";
 684             int start = alength >= 2 ? JS.toInt(arg1) : 0;
 685             // Java's indexOf handles an out of bounds start index, it'll return -1
 686             return JS.N(s.indexOf(search,start));
 687         }
 688         case "lastIndexOf": {
 689             String search = alength >= 1 ? JS.toString(arg0) : "null";
 690             int start = alength >= 2 ? JS.toInt(arg1) : 0;
 691             // Java's indexOf handles an out of bounds start index, it'll return -1
 692             return JS.N(s.lastIndexOf(search,start));
 693         }
 694         case "match": return JSRegexp.stringMatch(s,arg0);
 695         case "replace": return JSRegexp.stringReplace(s,arg0,arg1);
 696         case "search": return JSRegexp.stringSearch(s,arg0);
 697         case "split": return JSRegexp.stringSplit(s,arg0,arg1,alength);
 698         case "toLowerCase": return s.toLowerCase();
 699         case "toUpperCase": return s.toUpperCase();
 700         case "toString": return s;
 701         case "slice": {
 702             int a = alength >= 1 ? JS.toInt(arg0) : 0;
 703             int b = alength >= 2 ? JS.toInt(arg1) : slength;
 704             if (a < 0) a = slength + a;
 705             if (b < 0) b = slength + b;
 706             if (a < 0) a = 0;
 707             if (b < 0) b = 0;
 708             if (a > slength) a = slength;
 709             if (b > slength) b = slength;
 710             if (a > b) return "";
 711             return s.substring(a,b);
 712         }
 713         //#end
 714         throw new JSExn("Attempted to call non-existent method: " + method);
 715     }
 716
 717     static Object getFromPrimitive(Object o, Object key) throws JSExn {
 718         boolean returnJS = false;
 719         if (o instanceof Boolean) {
 720             throw new JSExn("Booleans do not have properties");
 721         } else if (o instanceof Number) {
 722             if (key.equals("toPrecision") || key.equals("toExponential") || key.equals("toFixed"))
 723                 returnJS = true;
 724         }
 725         if (!returnJS) {
 726             // the string stuff applies to everything
 727             String s = JS.toString(o);
 728
 729             // this is sort of ugly, but this list should never change
 730             // These should provide a complete (enough) implementation of the ECMA-262 String object
 731
 732             //#switch(key)
 733             case "length": return JS.N(s.length());
 734             case "substring": returnJS = true; break;
 735             case "charAt": returnJS = true; break;
 736             case "charCodeAt": returnJS = true; break;
 737             case "concat": returnJS = true; break;
 738             case "indexOf": returnJS = true; break;
 739             case "lastIndexOf": returnJS = true; break;
 740             case "match": returnJS = true; break;
 741             case "replace": returnJS = true; break;
 742             case "search": returnJS = true; break;
 743             case "slice": returnJS = true; break;
 744             case "split": returnJS = true; break;
 745             case "toLowerCase": returnJS = true; break;
 746             case "toUpperCase": returnJS = true; break;
 747             case "toString": returnJS = true; break;
 748             case "substr": returnJS = true; break;
 749            //#end
 750         }
 751         if (returnJS) {
 752             final Object target = o;
 753             final String method = JS.toString(o);
 754             return new JS() {
 755                     public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
 756                         if (nargs > 2) throw new JSExn("cannot call that method with that many arguments");
 757                         return callMethodOnPrimitive(target, method, a0, a1, a2, rest, nargs);
 758                     }
 759             };
 760         }
 761         return null;
 762     }
 763
 764     private static class Stub extends JS {
 765         private Object method;
 766         JS obj;
 767         public Stub(JS obj, Object method) { this.obj = obj; this.method = method; }
 768         public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
 769             return ((JS)obj).callMethod(method, a0, a1, a2, rest, nargs);
 770         }
 771     }
 772 }