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