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
  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 (scope instanceof Trap.TrapScope) { // handles return component of a read trap
 176                             Trap.TrapScope ts = (Trap.TrapScope)scope;
 177                             if (retval != null && retval instanceof Boolean && ((Boolean)retval).booleanValue())
 178                                 ts.cascadeHappened = true;
 179                             if (!ts.cascadeHappened) {
 180                                 ts.cascadeHappened = true;
 181                                 Trap t = ts.t.next;
 182                                 while (t != null && t.f.numFormalArgs == 0) t = t.next;
 183                                 if (t == null) {
 184                                     ((JS)ts.t.trapee).put(ts.t.name, ts.val);
 185                                     if (pausecount > initialPauseCount) { pc++; return null; }   // we were paused
 186                                 } else {
 187                                     stack.push(o);
 188                                     JSArray args = new JSArray();
 189                                     args.addElement(ts.val);
 190                                     stack.push(args);
 191                                     f = t.f;
 192                                     scope = new Trap.TrapScope(f.parentScope, t, ts.val);
 193                                     pc = -1;
 194                                     continue OUTER;
 195                                 }
 196                             }
 197                         }
 198                         scope = ((CallMarker)o).scope;
 199                         pc = ((CallMarker)o).pc - 1;
 200                         f = (JSFunction)((CallMarker)o).f;
 201                         stack.push(retval);
 202                         continue OUTER;
 203                     }
 204                 }
 205                 throw new Error("error: RETURN invoked but couldn't find a CallMarker!");
 206             }
 207
 208             case PUT: {
 209                 Object val = stack.pop();
 210                 Object key = stack.pop();
 211                 Object target = stack.peek();
 212                 if (target == null)
 213                     throw je("tried to put a value to the " + key + " property on the null value");
 214                 if (!(target instanceof JS))
 215                     throw je("tried to put a value to the " + key + " property on a " + target.getClass().getName());
 216                 if (key == null)
 217                     throw je("tried to assign \"" + (val==null?"(null)":val.toString()) + "\" to the null key");
 218
 219                 Trap t = null;
 220                 if (target instanceof Trap.TrapScope && key.equals("cascade")) {
 221                     Trap.TrapScope ts = (Trap.TrapScope)target;
 222                     t = ts.t.next;
 223                     ts.cascadeHappened = true;
 224                     while (t != null && t.f.numFormalArgs == 0) t = t.next;
 225                     if (t == null) { target = ts.t.trapee; key = ts.t.name; }
 226
 227                 } else if (target instanceof Trap.TrapScope && key.equals(((Trap.TrapScope)target).t.name)) {
 228                     throw je("tried to put to " + key + " inside a trap it owns; use cascade instead");
 229
 230                 } else if (target instanceof JS) {
 231                     if (target instanceof JSScope) {
 232                         JSScope p = (JSScope)target; // search the scope-path for the trap
 233                         t = p.getTrap(key);
 234                         while (t == null && p.getParentScope() != null) { p = p.getParentScope(); t = p.getTrap(key); }
 235                     } else {
 236                         t = ((JS)target).getTrap(key);
 237                     }
 238
 239                     while (t != null && t.f.numFormalArgs == 0) t = t.next; // find the first write trap
 240                     if (t != null) {
 241                         stack.push(new CallMarker(this));
 242                         JSArray args = new JSArray();
 243                         args.addElement(val);
 244                         stack.push(args);
 245                     }
 246                 }
 247                 if (t != null) {
 248                     stack.pop();
 249                     stack.push(new CallMarker(this));
 250                     stack.push(target);
 251                     JSArray args = new JSArray();
 252                     args.addElement(val);
 253                     f = t.f;
 254                     scope = new Trap.TrapScope(f.parentScope, t, val);
 255                     pc = -1;
 256                     break;
 257                 }
 258                 ((JS)target).put(key, val);
 259                 if (pausecount > initialPauseCount) { pc++; return null; }   // we were paused
 260                 stack.push(val);
 261                 break;
 262             }
 263
 264             case GET:
 265             case GET_PRESERVE: {
 266                 Object o, v;
 267                 if (op == GET) {
 268                     v = arg == null ? stack.pop() : arg;
 269                     o = stack.pop();
 270                 } else {
 271                     v = stack.pop();
 272                     o = stack.peek();
 273                     stack.push(v);
 274                 }
 275                 Object ret = null;
 276                 if (v == null) throw je("tried to get the null key from " + o);
 277                 if (o == null) throw je("tried to get property \"" + v + "\" from the null object");
 278                 if (o instanceof String || o instanceof Number || o instanceof Boolean) {
 279                     ret = getFromPrimitive(o,v);
 280                     stack.push(ret);
 281                     break;
 282                 } else if (o instanceof JS) {
 283                     Trap t = null;
 284                     if (o instanceof Trap.TrapScope && v.equals("cascade")) {
 285                         t = ((Trap.TrapScope)o).t.next;
 286                         while (t != null && t.f.numFormalArgs != 0) t = t.next;
 287                         if (t == null) { v = ((Trap.TrapScope)o).t.name; o = ((Trap.TrapScope)o).t.trapee; }
 288
 289                     } else if (o instanceof JS) {
 290                         if (o instanceof JSScope) {
 291                             JSScope p = (JSScope)o; // search the scope-path for the trap
 292                             t = p.getTrap(v);
 293                             while (t == null && p.getParentScope() != null) { p = p.getParentScope(); t = p.getTrap(v); }
 294                         } else {
 295                             t = ((JS)o).getTrap(v);
 296                         }
 297                         while (t != null && t.f.numFormalArgs != 0) t = t.next; // get first read trap
 298                     }
 299                     if (t != null) {
 300                         stack.push(new CallMarker(this));
 301                         JSArray args = new JSArray();
 302                         stack.push(args);
 303                         f = t.f;
 304                         scope = new Trap.TrapScope(f.parentScope, t, null);
 305                         ((Trap.TrapScope)scope).cascadeHappened = true;
 306                         pc = -1;
 307                         break;
 308                     }
 309                     ret = ((JS)o).get(v);
 310                     if (ret == JS.METHOD) ret = new Stub((JS)o, v);
 311                     if (pausecount > initialPauseCount) { pc++; return null; }   // we were paused
 312                     stack.push(ret);
 313                     break;
 314                 }
 315                 throw je("tried to get property " + v + " from a " + o.getClass().getName());
 316             }
 317
 318             case CALL: case CALLMETHOD: {
 319                 int numArgs = JS.toInt(arg);
 320                 Object method = null;
 321                 Object ret = null;
 322                 Object object = stack.pop();
 323
 324                 if (op == CALLMETHOD) {
 325                     if (object == JS.METHOD) {
 326                         method = stack.pop();
 327                         object = stack.pop();
 328                     } else if (object == null) {
 329                         Object name = stack.pop();
 330                         stack.pop();
 331                         throw new JSExn("function '"+name+"' not found");
 332                     } else {
 333                         stack.pop();
 334                         stack.pop();
 335                     }
 336                 }
 337                 Object[] rest = numArgs > 3 ? new Object[numArgs - 3] : null;
 338                 for(int i=numArgs - 1; i>2; i--) rest[i-3] = stack.pop();
 339                 Object a2 = numArgs <= 2 ? null : stack.pop();
 340                 Object a1 = numArgs <= 1 ? null : stack.pop();
 341                 Object a0 = numArgs <= 0 ? null : stack.pop();
 342
 343                 if (object instanceof String || object instanceof Number || object instanceof Boolean) {
 344                     ret = callMethodOnPrimitive(object, method, a0, a1, a2, null, numArgs);
 345
 346                 } else if (object instanceof JSFunction) {
 347                     // FIXME: use something similar to call0/call1/call2 here
 348                     JSArray arguments = new JSArray();
 349                     for(int i=0; i<numArgs; i++) arguments.addElement(i==0?a0:i==1?a1:i==2?a2:rest[i-3]);
 350                     stack.push(new CallMarker(this));
 351                     stack.push(arguments);
 352                     f = (JSFunction)object;
 353                     scope = new JSScope(f.parentScope);
 354                     pc = -1;
 355                     break;
 356
 357                 } else if (object instanceof JS) {
 358                     JS c = (JS)object;
 359                     ret = method == null ? c.call(a0, a1, a2, rest, numArgs) : c.callMethod(method, a0, a1, a2, rest, numArgs);
 360
 361                 } else {
 362                     throw new JSExn("can't call a " + object + " @" + pc + "\n" + f.dump());
 363
 364                 }
 365                 if (pausecount > initialPauseCount) { pc++; return null; }
 366                 stack.push(ret);
 367                 break;
 368             }
 369
 370             case THROW:
 371                 throw new JSExn(stack.pop());
 372                 /* FIXME
 373             case MAKE_GRAMMAR: {
 374                 final Grammar r = (Grammar)arg;
 375                 final JSScope final_scope = scope;
 376                 Grammar r2 = new Grammar() {
 377                         public int match(String s, int start, Hash v, JSScope scope) throws JSExn {
 378                             return r.match(s, start, v, final_scope);
 379                         }
 380                         public int matchAndWrite(String s, int start, Hash v, JSScope scope, String key) throws JSExn {
 381                             return r.matchAndWrite(s, start, v, final_scope, key);
 382                         }
 383                         public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
 384                             Hash v = new Hash();
 385                             r.matchAndWrite((String)a0, 0, v, final_scope, "foo");
 386                             return v.get("foo");
 387                         }
 388                     };
 389                 Object obj = stack.pop();
 390                 if (obj != null && obj instanceof Grammar) r2 = new Grammar.Alternative((Grammar)obj, r2);
 391                 stack.push(r2);
 392                 break;
 393             }
 394                 */
 395             case ADD_TRAP: case DEL_TRAP: {
 396                 Object val = stack.pop();
 397                 Object key = stack.pop();
 398                 Object obj = stack.peek();
 399                 // A trap addition/removal
 400                 JS js = obj instanceof JSScope ? ((JSScope)obj).top() : (JS) obj;
 401                 if(op == ADD_TRAP) js.addTrap(key, (JSFunction)val);
 402                 else js.delTrap(key, (JSFunction)val);
 403                 break;
 404             }
 405
 406             case ASSIGN_SUB: case ASSIGN_ADD: {
 407                 Object val = stack.pop();
 408                 Object key = stack.pop();
 409                 Object obj = stack.peek();
 410                 // The following setup is VERY important. The generated bytecode depends on the stack
 411                 // being setup like this (top to bottom) KEY, OBJ, VAL, KEY, OBJ
 412                 stack.push(key);
 413                 stack.push(val);
 414                 stack.push(obj);
 415                 stack.push(key);
 416                 break;
 417             }
 418
 419             case ADD: {
 420                 int count = ((Number)arg).intValue();
 421                 if(count < 2) throw new Error("this should never happen");
 422                 if(count == 2) {
 423                     // common case
 424                     Object right = stack.pop();
 425                     Object left = stack.pop();
 426                     if(left instanceof String || right instanceof String)
 427                         stack.push(JS.toString(left).concat(JS.toString(right)));
 428                     else stack.push(JS.N(JS.toDouble(left) + JS.toDouble(right)));
 429                 } else {
 430                     Object[] args = new Object[count];
 431                     while(--count >= 0) args[count] = stack.pop();
 432                     if(args[0] instanceof String) {
 433                         StringBuffer sb = new StringBuffer(64);
 434                         for(int i=0;i<args.length;i++) sb.append(JS.toString(args[i]));
 435                         stack.push(sb.toString());
 436                     } else {
 437                         int numStrings = 0;
 438                         for(int i=0;i<args.length;i++) if(args[i] instanceof String) numStrings++;
 439                         if(numStrings == 0) {
 440                             double d = 0.0;
 441                             for(int i=0;i<args.length;i++) d += JS.toDouble(args[i]);
 442                             stack.push(JS.N(d));
 443                         } else {
 444                             int i=0;
 445                             StringBuffer sb = new StringBuffer(64);
 446                             if(!(args[0] instanceof String || args[1] instanceof String)) {
 447                                 double d=0.0;
 448                                 do {
 449                                     d += JS.toDouble(args[i++]);
 450                                 } while(!(args[i] instanceof String));
 451                                 sb.append(JS.toString(JS.N(d)));
 452                             }
 453                             while(i < args.length) sb.append(JS.toString(args[i++]));
 454                             stack.push(sb.toString());
 455                         }
 456                     }
 457                 }
 458                 break;
 459             }
 460
 461             default: {
 462                 Object right = stack.pop();
 463                 Object left = stack.pop();
 464                 switch(op) {
 465
 466                 case BITOR: stack.push(JS.N(JS.toLong(left) | JS.toLong(right))); break;
 467                 case BITXOR: stack.push(JS.N(JS.toLong(left) ^ JS.toLong(right))); break;
 468                 case BITAND: stack.push(JS.N(JS.toLong(left) & JS.toLong(right))); break;
 469
 470                 case SUB: stack.push(JS.N(JS.toDouble(left) - JS.toDouble(right))); break;
 471                 case MUL: stack.push(JS.N(JS.toDouble(left) * JS.toDouble(right))); break;
 472                 case DIV: stack.push(JS.N(JS.toDouble(left) / JS.toDouble(right))); break;
 473                 case MOD: stack.push(JS.N(JS.toDouble(left) % JS.toDouble(right))); break;
 474
 475                 case LSH: stack.push(JS.N(JS.toLong(left) << JS.toLong(right))); break;
 476                 case RSH: stack.push(JS.N(JS.toLong(left) >> JS.toLong(right))); break;
 477                 case URSH: stack.push(JS.N(JS.toLong(left) >>> JS.toLong(right))); break;
 478
 479                 case LT: case LE: case GT: case GE: {
 480                     if (left == null) left = JS.N(0);
 481                     if (right == null) right = JS.N(0);
 482                     int result = 0;
 483                     if (left instanceof String || right instanceof String) {
 484                         result = left.toString().compareTo(right.toString());
 485                     } else {
 486                         result = (int)java.lang.Math.ceil(JS.toDouble(left) - JS.toDouble(right));
 487                     }
 488                     stack.push(JS.B((op == LT && result < 0) || (op == LE && result <= 0) ||
 489                                (op == GT && result > 0) || (op == GE && result >= 0)));
 490                     break;
 491                 }
 492
 493                 case EQ:
 494                 case NE: {
 495                     Object l = left;
 496                     Object r = right;
 497                     boolean ret;
 498                     if (l == null) { Object tmp = r; r = l; l = tmp; }
 499                     if (l == null && r == null) ret = true;
 500                     else if (r == null) ret = false; // l != null, so its false
 501                     else if (l instanceof Boolean) ret = JS.B(JS.toBoolean(r)).equals(l);
 502                     else if (l instanceof Number) ret = JS.toNumber(r).doubleValue() == JS.toNumber(l).doubleValue();
 503                     else if (l instanceof String) ret = r != null && l.equals(r.toString());
 504                     else ret = l.equals(r);
 505                     stack.push(JS.B(op == EQ ? ret : !ret)); break;
 506                 }
 507
 508                 default: throw new Error("unknown opcode " + op);
 509                 } }
 510             }
 511
 512         } catch(JSExn e) {
 513             if(f.op[pc] != FINALLY_DONE) e.addBacktrace(f.sourceName,f.line[pc]);
 514             while(stack.size() > 0) {
 515                 Object o = stack.pop();
 516                 if (o instanceof CatchMarker || o instanceof TryMarker) {
 517                     boolean inCatch = o instanceof CatchMarker;
 518                     if(inCatch) {
 519                         o = stack.pop();
 520                         if(((TryMarker)o).finallyLoc < 0) continue; // no finally block, keep going
 521                     }
 522                     if(!inCatch && ((TryMarker)o).catchLoc >= 0) {
 523                         // run the catch block, this will implicitly run the finally block, if it exists
 524                         stack.push(o);
 525                         stack.push(catchMarker);
 526                         stack.push(e.getObject());
 527                         f = ((TryMarker)o).f;
 528                         scope = ((TryMarker)o).scope;
 529                         pc = ((TryMarker)o).catchLoc - 1;
 530                         continue OUTER;
 531                     } else {
 532                         stack.push(new FinallyData(e));
 533                         f = ((TryMarker)o).f;
 534                         scope = ((TryMarker)o).scope;
 535                         pc = ((TryMarker)o).finallyLoc - 1;
 536                         continue OUTER;
 537                     }
 538                 } else if(o instanceof CallMarker) {
 539                     CallMarker cm = (CallMarker) o;
 540                     if(cm.f == null)
 541                         e.addBacktrace("<java>",0); // This might not even be worth mentioning
 542                     else
 543                         e.addBacktrace(cm.f.sourceName,cm.f.line[cm.pc-1]);
 544                 }
 545             }
 546             throw e;
 547         } // end try/catch
 548         } // end for
 549     }
 550
 551
 552
 553     // Markers //////////////////////////////////////////////////////////////////////
 554
 555     public static class CallMarker {
 556         int pc;
 557         JSScope scope;
 558         JSFunction f;
 559         public CallMarker(Interpreter cx) { pc = cx.pc + 1; scope = cx.scope; f = cx.f; }
 560     }
 561
 562     public static class CatchMarker { }
 563     private static CatchMarker catchMarker = new CatchMarker();
 564
 565     public static class LoopMarker {
 566         public int location;
 567         public String label;
 568         public JSScope scope;
 569         public LoopMarker(int location, String label, JSScope scope) {
 570             this.location = location;
 571             this.label = label;
 572             this.scope = scope;
 573         }
 574     }
 575     public static class TryMarker {
 576         public int catchLoc;
 577         public int finallyLoc;
 578         public JSScope scope;
 579         public JSFunction f;
 580         public TryMarker(int catchLoc, int finallyLoc, Interpreter cx) {
 581             this.catchLoc = catchLoc;
 582             this.finallyLoc = finallyLoc;
 583             this.scope = cx.scope;
 584             this.f = cx.f;
 585         }
 586     }
 587     public static class FinallyData {
 588         public int op;
 589         public Object arg;
 590         public JSExn exn;
 591         public FinallyData(int op) { this(op,null); }
 592         public FinallyData(int op, Object arg) { this.op = op; this.arg = arg; }
 593         public FinallyData(JSExn exn) { this.exn = exn; } // Just throw this exn
 594     }
 595
 596
 597     // Operations on Primitives //////////////////////////////////////////////////////////////////////
 598
 599     static Object callMethodOnPrimitive(Object o, Object method, Object arg0, Object arg1, Object arg2, Object[] rest, int alength) throws JSExn {
 600         if (method == null || !(method instanceof String) || "".equals(method))
 601             throw new JSExn("attempt to call a non-existant method on a primitive");
 602
 603         if (o instanceof Number) {
 604             //#switch(method)
 605             case "toFixed": throw new JSExn("toFixed() not implemented");
 606             case "toExponential": throw new JSExn("toExponential() not implemented");
 607             case "toPrecision": throw new JSExn("toPrecision() not implemented");
 608             case "toString": {
 609                 int radix = alength >= 1 ? JS.toInt(arg0) : 10;
 610                 return Long.toString(((Number)o).longValue(),radix);
 611             }
 612             //#end
 613         } else if (o instanceof Boolean) {
 614             // No methods for Booleans
 615             throw new JSExn("attempt to call a method on a Boolean");
 616         }
 617
 618         String s = JS.toString(o);
 619         int slength = s.length();
 620         //#switch(method)
 621         case "substring": {
 622             int a = alength >= 1 ? JS.toInt(arg0) : 0;
 623             int b = alength >= 2 ? JS.toInt(arg1) : slength;
 624             if (a > slength) a = slength;
 625             if (b > slength) b = slength;
 626             if (a < 0) a = 0;
 627             if (b < 0) b = 0;
 628             if (a > b) { int tmp = a; a = b; b = tmp; }
 629             return s.substring(a,b);
 630         }
 631         case "substr": {
 632             int start = alength >= 1 ? JS.toInt(arg0) : 0;
 633             int len = alength >= 2 ? JS.toInt(arg1) : Integer.MAX_VALUE;
 634             if (start < 0) start = slength + start;
 635             if (start < 0) start = 0;
 636             if (len < 0) len = 0;
 637             if (len > slength - start) len = slength - start;
 638             if (len <= 0) return "";
 639             return s.substring(start,start+len);
 640         }
 641         case "charAt": {
 642             int p = alength >= 1 ? JS.toInt(arg0) : 0;
 643             if (p < 0 || p >= slength) return "";
 644             return s.substring(p,p+1);
 645         }
 646         case "charCodeAt": {
 647             int p = alength >= 1 ? JS.toInt(arg0) : 0;
 648             if (p < 0 || p >= slength) return JS.N(Double.NaN);
 649             return JS.N(s.charAt(p));
 650         }
 651         case "concat": {
 652             StringBuffer sb = new StringBuffer(slength*2).append(s);
 653             for(int i=0;i<alength;i++) sb.append(i==0?arg0:i==1?arg1:i==2?arg2:rest[i-3]);
 654             return sb.toString();
 655         }
 656         case "indexOf": {
 657             String search = alength >= 1 ? arg0.toString() : "null";
 658             int start = alength >= 2 ? JS.toInt(arg1) : 0;
 659             // Java's indexOf handles an out of bounds start index, it'll return -1
 660             return JS.N(s.indexOf(search,start));
 661         }
 662         case "lastIndexOf": {
 663             String search = alength >= 1 ? arg0.toString() : "null";
 664             int start = alength >= 2 ? JS.toInt(arg1) : 0;
 665             // Java's indexOf handles an out of bounds start index, it'll return -1
 666             return JS.N(s.lastIndexOf(search,start));
 667         }
 668         case "match": return JSRegexp.stringMatch(s,arg0);
 669         case "replace": return JSRegexp.stringReplace(s,arg0,arg1);
 670         case "search": return JSRegexp.stringSearch(s,arg0);
 671         case "split": return JSRegexp.stringSplit(s,arg0,arg1,alength);
 672         case "toLowerCase": return s.toLowerCase();
 673         case "toUpperCase": return s.toUpperCase();
 674         case "toString": return s;
 675         case "slice": {
 676             int a = alength >= 1 ? JS.toInt(arg0) : 0;
 677             int b = alength >= 2 ? JS.toInt(arg1) : slength;
 678             if (a < 0) a = slength + a;
 679             if (b < 0) b = slength + b;
 680             if (a < 0) a = 0;
 681             if (b < 0) b = 0;
 682             if (a > slength) a = slength;
 683             if (b > slength) b = slength;
 684             if (a > b) return "";
 685             return s.substring(a,b);
 686         }
 687         //#end
 688         throw new JSExn("Attempted to call non-existent method: " + method);
 689     }
 690
 691     static Object getFromPrimitive(Object o, Object key) throws JSExn {
 692         boolean returnJS = false;
 693         if (o instanceof Boolean) {
 694             throw new JSExn("cannot call methods on Booleans");
 695         } else if (o instanceof Number) {
 696             if (key.equals("toPrecision") || key.equals("toExponential") || key.equals("toFixed"))
 697                 returnJS = true;
 698         }
 699         if (!returnJS) {
 700             // the string stuff applies to everything
 701             String s = o.toString();
 702
 703             // this is sort of ugly, but this list should never change
 704             // These should provide a complete (enough) implementation of the ECMA-262 String object
 705
 706             //#switch(key)
 707             case "length": return JS.N(s.length());
 708             case "substring": returnJS = true; break;
 709             case "charAt": returnJS = true; break;
 710             case "charCodeAt": returnJS = true; break;
 711             case "concat": returnJS = true; break;
 712             case "indexOf": returnJS = true; break;
 713             case "lastIndexOf": returnJS = true; break;
 714             case "match": returnJS = true; break;
 715             case "replace": returnJS = true; break;
 716             case "seatch": returnJS = true; break;
 717             case "slice": returnJS = true; break;
 718             case "split": returnJS = true; break;
 719             case "toLowerCase": returnJS = true; break;
 720             case "toUpperCase": returnJS = true; break;
 721             case "toString": returnJS = true; break;
 722             case "substr": returnJS = true; break;
 723            //#end
 724         }
 725         if (returnJS) {
 726             final Object target = o;
 727             final String method = key.toString();
 728             return new JS() {
 729                     public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
 730                         if (nargs > 2) throw new JSExn("cannot call that method with that many arguments");
 731                         return callMethodOnPrimitive(target, method, a0, a1, a2, rest, nargs);
 732                     }
 733             };
 734         }
 735         return null;
 736     }
 737
 738     private static class Stub extends JS {
 739         private Object method;
 740         JS obj;
 741         public Stub(JS obj, Object method) { this.obj = obj; this.method = method; }
 742         public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
 743             return ((JS)obj).callMethod(method, a0, a1, a2, rest, nargs);
 744         }
 745     }
 746 }