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 class Interpreter implements ByteCodes, Tokens {
   9
  10     static Object eval(final JSContext cx) throws JS.Exn {
  11         final int initialPauseCount = cx.pausecount;
  12         OUTER: for(;; cx.pc++) {
  13         try {
  14             if (cx.f == null || cx.pc >= cx.f.size) return cx.stack.pop();
  15             int op = cx.f.op[cx.pc];
  16             Object arg = cx.f.arg[cx.pc];
  17             if(op == FINALLY_DONE) {
  18                 FinallyData fd = (FinallyData) cx.stack.pop();
  19                 if(fd == null) continue OUTER; // NOP
  20                 op = fd.op;
  21                 arg = fd.arg;
  22             }
  23             switch(op) {
  24             case LITERAL: cx.stack.push(arg); break;
  25             case OBJECT: cx.stack.push(new JS()); break;
  26             case ARRAY: cx.stack.push(new JSArray(JS.toNumber(arg).intValue())); break;
  27             case DECLARE: cx.scope.declare((String)(arg==null ? cx.stack.peek() : arg)); if(arg != null) cx.stack.push(arg); break;
  28             case TOPSCOPE: cx.stack.push(cx.scope); break;
  29             case JT: if (JS.toBoolean(cx.stack.pop())) cx.pc += JS.toNumber(arg).intValue() - 1; break;
  30             case JF: if (!JS.toBoolean(cx.stack.pop())) cx.pc += JS.toNumber(arg).intValue() - 1; break;
  31             case JMP: cx.pc += JS.toNumber(arg).intValue() - 1; break;
  32             case POP: cx.stack.pop(); break;
  33             case SWAP: {
  34                 int depth = (arg == null ? 1 : JS.toInt(arg));
  35                 Object save = cx.stack.elementAt(cx.stack.size() - 1);
  36                 for(int i=cx.stack.size() - 1; i > cx.stack.size() - 1 - depth; i--)
  37                     cx.stack.setElementAt(cx.stack.elementAt(i-1), i);
  38                 cx.stack.setElementAt(save, cx.stack.size() - depth - 1);
  39                 break; }
  40             case DUP: cx.stack.push(cx.stack.peek()); break;
  41             case NEWSCOPE: cx.scope = new JSScope(cx.scope); break;
  42             case OLDSCOPE: cx.scope = cx.scope.getParentJSScope(); break;
  43             case ASSERT: if (!JS.toBoolean(cx.stack.pop())) throw je("assertion failed"); break;
  44             case BITNOT: cx.stack.push(new Long(~JS.toLong(cx.stack.pop()))); break;
  45             case BANG: cx.stack.push(new Boolean(!JS.toBoolean(cx.stack.pop()))); break;
  46             case NEWFUNCTION: cx.stack.push(((JSFunction)arg).cloneWithNewParentJSScope(cx.scope)); break;
  47             case LABEL: break;
  48
  49             case TYPEOF: {
  50                 Object o = cx.stack.pop();
  51                 if (o == null) cx.stack.push(null);
  52                 else if (o instanceof JS) cx.stack.push(((JS)o).typeName());
  53                 else if (o instanceof String) cx.stack.push("string");
  54                 else if (o instanceof Number) cx.stack.push("number");
  55                 else if (o instanceof Boolean) cx.stack.push("boolean");
  56                 else cx.stack.push("unknown");
  57                 break;
  58             }
  59
  60             case PUSHKEYS: {
  61                 Object o = cx.stack.peek();
  62                 Enumeration e = ((JS)o).keys();
  63                 JSArray a = new JSArray();
  64                 while(e.hasMoreElements()) a.addElement(e.nextElement());
  65                 cx.stack.push(a);
  66                 break;
  67             }
  68
  69             case LOOP:
  70                 cx.stack.push(new LoopMarker(cx.pc, cx.pc > 0 && cx.f.op[cx.pc - 1] == LABEL ?
  71                                              (String)cx.f.arg[cx.pc - 1] : (String)null, cx.scope));
  72                 cx.stack.push(Boolean.TRUE);
  73                 break;
  74
  75             case BREAK:
  76             case CONTINUE:
  77                 while(cx.stack.size() > 0) {
  78                     Object o = cx.stack.pop();
  79                     if (o instanceof CallMarker) ee("break or continue not within a loop");
  80                     if (o instanceof TryMarker) {
  81                         if(((TryMarker)o).finallyLoc < 0) continue; // no finally block, keep going
  82                         cx.stack.push(new FinallyData(op, arg));
  83                         cx.scope = ((TryMarker)o).scope;
  84                         cx.pc = ((TryMarker)o).finallyLoc - 1;
  85                         continue OUTER;
  86                     }
  87                     if (o instanceof LoopMarker) {
  88                         if (arg == null || arg.equals(((LoopMarker)o).label)) {
  89                             int loopInstructionLocation = ((LoopMarker)o).location;
  90                             int endOfLoop = ((Integer)cx.f.arg[loopInstructionLocation]).intValue() + loopInstructionLocation;
  91                             cx.scope = ((LoopMarker)o).scope;
  92                             if (op == CONTINUE) { cx.stack.push(o); cx.stack.push(Boolean.FALSE); }
  93                             cx.pc = op == BREAK ? endOfLoop - 1 : loopInstructionLocation;
  94                             continue OUTER;
  95                         }
  96                     }
  97                 }
  98                 throw new Error("CONTINUE/BREAK invoked but couldn't find LoopMarker at " +
  99                                 cx.getSourceName() + ":" + cx.getLine());
 100
 101             case TRY: {
 102                 int[] jmps = (int[]) arg;
 103                 // jmps[0] is how far away the catch block is, jmps[1] is how far away the finally block is
 104                 // each can be < 0 if the specified block does not exist
 105                 cx.stack.push(new TryMarker(jmps[0] < 0 ? -1 : cx.pc + jmps[0], jmps[1] < 0 ? -1 : cx.pc + jmps[1], cx.scope));
 106                 break;
 107             }
 108
 109             case RETURN: {
 110                 Object retval = cx.stack.pop();
 111                 while(cx.stack.size() > 0) {
 112                     Object o = cx.stack.pop();
 113                     if (o instanceof TryMarker) {
 114                         if(((TryMarker)o).finallyLoc < 0) continue;
 115                         cx.stack.push(retval);
 116                         cx.stack.push(new FinallyData(RETURN));
 117                         cx.scope = ((TryMarker)o).scope;
 118                         cx.pc = ((TryMarker)o).finallyLoc - 1;
 119                         continue OUTER;
 120                     } else if (o instanceof CallMarker) {
 121                         if (cx.scope instanceof JSTrap.JSTrapScope) {
 122                             JSTrap.JSTrapScope ts = (JSTrap.JSTrapScope)cx.scope;
 123                             if (!ts.cascadeHappened) {
 124                                 ts.cascadeHappened = true;
 125                                 JSTrap t = ts.t.next;
 126                                 while (t != null && t.f.numFormalArgs == 0) t = t.next;
 127                                 if (t == null) {
 128                                     ((JS)ts.t.trapee).put(t.name, ts.val);
 129                                     if (cx.pausecount > initialPauseCount) return null;   // we were paused
 130                                 } else {
 131                                     cx.stack.push(o);
 132                                     JSArray args = new JSArray();
 133                                     args.addElement(ts.val);
 134                                     cx.stack.push(args);
 135                                     cx.f = t.f;
 136                                     cx.scope = new JSTrap.JSTrapScope(cx.f.parentJSScope, t, ts.val);
 137                                     cx.pc = -1;
 138                                     break;
 139                                 }
 140                             }
 141                         }
 142                         cx.scope = ((CallMarker)o).scope;
 143                         cx.pc = ((CallMarker)o).pc;
 144                         cx.f = (JSFunction)((CallMarker)o).f;
 145                         cx.stack.push(retval);
 146                         continue OUTER;
 147                     }
 148                 }
 149                 throw new Error("error: RETURN invoked but couldn't find a CallMarker!");
 150             }
 151
 152             case PUT: {
 153                 Object val = cx.stack.pop();
 154                 Object key = cx.stack.pop();
 155                 Object target = cx.stack.peek();
 156                 if (target == null)
 157                     throw je("tried to put a value to the " + key + " property on the null value");
 158                 if (!(target instanceof JS))
 159                     throw je("tried to put a value to the " + key + " property on a " + target.getClass().getName());
 160                 if (key == null)
 161                     throw je("tried to assign \"" + (val==null?"(null)":val.toString()) + "\" to the null key");
 162                 JSTrap t = null;
 163                 if (target instanceof JSTrap.JSTrappable) {
 164                     t = ((JSTrap.JSTrappable)target).getTrap(val);
 165                     while (t != null && t.f.numFormalArgs == 0) t = t.next;
 166                 } else if (target instanceof JSTrap.JSTrapScope && key.equals("cascade")) {
 167                     JSTrap.JSTrapScope ts = (JSTrap.JSTrapScope)target;
 168                     t = ts.t.next;
 169                     ts.cascadeHappened = true;
 170                     while (t != null && t.f.numFormalArgs == 0) t = t.next;
 171                     if (t == null) target = ts.t.trapee;
 172                 }
 173                 if (t != null) {
 174                     cx.stack.push(new CallMarker(cx));
 175                     JSArray args = new JSArray();
 176                     args.addElement(val);
 177                     cx.stack.push(args);
 178                     cx.f = t.f;
 179                     cx.scope = new JSTrap.JSTrapScope(cx.f.parentJSScope, t, val);
 180                     cx.pc = -1;
 181                     break;
 182                 }
 183                 ((JS)target).put(key, val);
 184                 if (cx.pausecount > initialPauseCount) return null;   // we were paused
 185                 cx.stack.push(val);
 186                 break;
 187             }
 188
 189             case GET:
 190             case GET_PRESERVE: {
 191                 Object o, v;
 192                 if (op == GET) {
 193                     v = arg == null ? cx.stack.pop() : arg;
 194                     o = cx.stack.pop();
 195                 } else {
 196                     v = cx.stack.pop();
 197                     o = cx.stack.peek();
 198                     cx.stack.push(v);
 199                 }
 200                 Object ret = null;
 201                 if (v == null) throw je("tried to get the null key from " + o);
 202                 if (o == null) throw je("tried to get property \"" + v + "\" from the null value @" + cx.pc + "\n" + cx.f.dump());
 203                 if (o instanceof String || o instanceof Number || o instanceof Boolean) {
 204                     ret = Internal.getFromPrimitive(o,v);
 205                     cx.stack.push(ret);
 206                     break;
 207                 } else if (o instanceof JS) {
 208                     JSTrap t = null;
 209                     if (o instanceof JSTrap.JSTrappable) {
 210                         t = ((JSTrap.JSTrappable)o).getTrap(v);
 211                         while (t != null && t.f.numFormalArgs != 0) t = t.next;
 212                     } else if (o instanceof JSTrap.JSTrapScope && v.equals("cascade")) {
 213                         t = ((JSTrap.JSTrapScope)o).t.next;
 214                         while (t != null && t.f.numFormalArgs != 0) t = t.next;
 215                         if (t == null) o = ((JSTrap.JSTrapScope)o).t.trapee;
 216                     }
 217                     if (t != null) {
 218                         cx.stack.push(new CallMarker(cx));
 219                         JSArray args = new JSArray();
 220                         cx.stack.push(args);
 221                         cx.f = t.f;
 222                         cx.scope = new JSTrap.JSTrapScope(cx.f.parentJSScope, t, null);
 223                         ((JSTrap.JSTrapScope)cx.scope).cascadeHappened = true;
 224                         cx.pc = -1;
 225                         break;
 226                     }
 227                     ret = ((JS)o).get(v);
 228                     if (ret == JSCallable.METHOD) ret = new Internal.JSCallableStub((JS)o, v);
 229                     if (cx.pausecount > initialPauseCount) return null;   // we were paused
 230                     cx.stack.push(ret);
 231                     break;
 232                 }
 233                 throw je("tried to get property " + v + " from a " + o.getClass().getName());
 234             }
 235
 236             case CALL: case CALLMETHOD: {
 237                 int numArgs = JS.toInt(arg);
 238                 Object method = null;
 239                 Object ret = null;
 240                 Object object = cx.stack.pop();
 241
 242                 if (op == CALL) {
 243                     object = cx.stack.pop();
 244                 } else if (object == JSCallable.METHOD) {
 245                     method = cx.stack.pop();
 246                     object = cx.stack.pop();
 247                 }
 248
 249                 if (object instanceof String || object instanceof Number || object instanceof Boolean) {
 250                     JSArray arguments = new JSArray();
 251                     for(int j=numArgs - 1; j >= 0; j--) arguments.setElementAt(cx.stack.pop(), j);
 252                     ret = Internal.callMethodOnPrimitive(object, method, arguments);
 253
 254                 } else if (object instanceof JSFunction) {
 255                     // FEATURE: use something similar to call0/call1/call2 here
 256                     JSArray arguments = new JSArray();
 257                     for(int j=numArgs - 1; j >= 0; j--) arguments.setElementAt(cx.stack.pop(), j);
 258                     cx.stack.push(new CallMarker(cx));
 259                     cx.stack.push(arguments);
 260                     cx.f = (JSFunction)object;
 261                     cx.scope = new JSScope(cx.f.parentJSScope);
 262                     cx.pc = -1;
 263                     break;
 264
 265                 } else if (object instanceof JSCallable) {
 266                     JSCallable c = (JSCallable)object;
 267                     Object[] rest = numArgs > 3 ? new Object[numArgs - 3] : null;
 268                     for(int i=numArgs - 1; i>2; i--) rest[i-3] = cx.stack.pop();
 269                     Object a2 = numArgs <= 2 ? null : cx.stack.pop();
 270                     Object a1 = numArgs <= 1 ? null : cx.stack.pop();
 271                     Object a0 = numArgs <= 0 ? null : cx.stack.pop();
 272                     ret = c.callMethod(method, a0, a1, a2, rest, numArgs);
 273
 274                 } else {
 275                     throw new JS.Exn("can't call a " + object.getClass().getName() + " @" + cx.pc + "\n" + cx.f.dump());
 276
 277                 }
 278                 if (cx.pausecount > initialPauseCount) return null;
 279                 cx.stack.push(ret);
 280                 break;
 281             }
 282
 283             case THROW: {
 284                 Object o = cx.stack.pop();
 285                 if(o instanceof JS.Exn) throw (JS.Exn)o;
 286                 throw new JS.Exn(o);
 287             }
 288
 289             case ASSIGN_SUB: case ASSIGN_ADD: {
 290                 Object val = cx.stack.pop();
 291                 Object old = cx.stack.pop();
 292                 Object key = cx.stack.pop();
 293                 Object obj = cx.stack.peek();
 294                 if (val instanceof JSFunction && obj instanceof JSScope) {
 295                     JSScope parent = (JSScope)obj;
 296                     while(parent.getParentJSScope() != null) parent = parent.getParentJSScope();
 297                     if (parent instanceof JSTrap.JSTrappable) {
 298                         JSTrap.JSTrappable b = (JSTrap.JSTrappable)parent;
 299                         if (op == ASSIGN_ADD) JSTrap.addTrap(b, key, (JSFunction)val);
 300                         else JSTrap.delTrap(b, key, (JSFunction)val);
 301                         // skip over the "normal" implementation of +=/-=
 302                         cx.pc += ((Integer)arg).intValue() - 1;
 303                         break;
 304                     }
 305                 }
 306                 // use the "normal" implementation
 307                 cx.stack.push(key);
 308                 cx.stack.push(old);
 309                 cx.stack.push(val);
 310                 break;
 311             }
 312
 313             case ADD: {
 314                 int count = ((Number)arg).intValue();
 315                 if(count < 2) throw new Error("this should never happen");
 316                 if(count == 2) {
 317                     // common case
 318                     Object right = cx.stack.pop();
 319                     Object left = cx.stack.pop();
 320                     if(left instanceof String || right instanceof String)
 321                         cx.stack.push(JS.toString(left).concat(JS.toString(right)));
 322                     else cx.stack.push(new Double(JS.toDouble(left) + JS.toDouble(right)));
 323                 } else {
 324                     Object[] args = new Object[count];
 325                     while(--count >= 0) args[count] = cx.stack.pop();
 326                     if(args[0] instanceof String) {
 327                         StringBuffer sb = new StringBuffer(64);
 328                         for(int i=0;i<args.length;i++) sb.append(JS.toString(args[i]));
 329                         cx.stack.push(sb.toString());
 330                     } else {
 331                         int numStrings = 0;
 332                         for(int i=0;i<args.length;i++) if(args[i] instanceof String) numStrings++;
 333                         if(numStrings == 0) {
 334                             double d = 0.0;
 335                             for(int i=0;i<args.length;i++) d += JS.toDouble(args[i]);
 336                             cx.stack.push(new Double(d));
 337                         } else {
 338                             int i=0;
 339                             StringBuffer sb = new StringBuffer(64);
 340                             if(!(args[0] instanceof String || args[1] instanceof String)) {
 341                                 double d=0.0;
 342                                 do {
 343                                     d += JS.toDouble(args[i++]);
 344                                 } while(!(args[i] instanceof String));
 345                                 sb.append(JS.toString(new Double(d)));
 346                             }
 347                             while(i < args.length) sb.append(JS.toString(args[i++]));
 348                             cx.stack.push(sb.toString());
 349                         }
 350                     }
 351                 }
 352                 break;
 353             }
 354
 355             default: {
 356                 Object right = cx.stack.pop();
 357                 Object left = cx.stack.pop();
 358                 switch(op) {
 359
 360                 case BITOR: cx.stack.push(new Long(JS.toLong(left) | JS.toLong(right))); break;
 361                 case BITXOR: cx.stack.push(new Long(JS.toLong(left) ^ JS.toLong(right))); break;
 362                 case BITAND: cx.stack.push(new Long(JS.toLong(left) & JS.toLong(right))); break;
 363
 364                 case SUB: cx.stack.push(new Double(JS.toDouble(left) - JS.toDouble(right))); break;
 365                 case MUL: cx.stack.push(new Double(JS.toDouble(left) * JS.toDouble(right))); break;
 366                 case DIV: cx.stack.push(new Double(JS.toDouble(left) / JS.toDouble(right))); break;
 367                 case MOD: cx.stack.push(new Double(JS.toDouble(left) % JS.toDouble(right))); break;
 368
 369                 case LSH: cx.stack.push(new Long(JS.toLong(left) << JS.toLong(right))); break;
 370                 case RSH: cx.stack.push(new Long(JS.toLong(left) >> JS.toLong(right))); break;
 371                 case URSH: cx.stack.push(new Long(JS.toLong(left) >>> JS.toLong(right))); break;
 372
 373                 case LT: case LE: case GT: case GE: {
 374                     if (left == null) left = new Integer(0);
 375                     if (right == null) right = new Integer(0);
 376                     int result = 0;
 377                     if (left instanceof String || right instanceof String) {
 378                         result = left.toString().compareTo(right.toString());
 379                     } else {
 380                         result = (int)java.lang.Math.ceil(JS.toDouble(left) - JS.toDouble(right));
 381                     }
 382                     cx.stack.push(new Boolean((op == LT && result < 0) || (op == LE && result <= 0) ||
 383                                        (op == GT && result > 0) || (op == GE && result >= 0)));
 384                     break;
 385                 }
 386
 387                 case EQ:
 388                 case NE: {
 389                     Object l = left;
 390                     Object r = right;
 391                     boolean ret;
 392                     if (l == null) { Object tmp = r; r = l; l = tmp; }
 393                     if (l == null && r == null) ret = true;
 394                     else if (r == null) ret = false; // l != null, so its false
 395                     else if (l instanceof Boolean) ret = new Boolean(JS.toBoolean(r)).equals(l);
 396                     else if (l instanceof Number) ret = JS.toNumber(r).doubleValue() == JS.toNumber(l).doubleValue();
 397                     else if (l instanceof String) ret = r != null && l.equals(r.toString());
 398                     else ret = l.equals(r);
 399                     cx.stack.push(new Boolean(op == EQ ? ret : !ret)); break;
 400                 }
 401
 402                 default: throw new Error("unknown opcode " + op);
 403                 } }
 404             }
 405
 406         } catch(JS.Exn e) {
 407             while(cx.stack.size() > 0) {
 408                 Object o = cx.stack.pop();
 409                 if (o instanceof CatchMarker || o instanceof TryMarker) {
 410                     boolean inCatch = o instanceof CatchMarker;
 411                     if(inCatch) {
 412                         o = cx.stack.pop();
 413                         if(((TryMarker)o).finallyLoc < 0) continue; // no finally block, keep going
 414                     }
 415                     if(!inCatch && ((TryMarker)o).catchLoc >= 0) {
 416                         // run the catch block, this will implicitly run the finally block, if it exists
 417                         cx.stack.push(o);
 418                         cx.stack.push(catchMarker);
 419                         cx.stack.push(e.getObject());
 420                         cx.scope = ((TryMarker)o).scope;
 421                         cx.pc = ((TryMarker)o).catchLoc - 1;
 422                         continue OUTER;
 423                     } else {
 424                         cx.stack.push(e);
 425                         cx.stack.push(new FinallyData(THROW));
 426                         cx.scope = ((TryMarker)o).scope;
 427                         cx.pc = ((TryMarker)o).finallyLoc - 1;
 428                         continue OUTER;
 429                     }
 430                 }
 431                 // no handler found within this func
 432                 if(o instanceof CallMarker) throw e;
 433             }
 434             throw e;
 435         } // end try/catch
 436         } // end for
 437     }
 438
 439     // Exception Stuff ////////////////////////////////////////////////////////////////
 440
 441     static class EvaluatorException extends RuntimeException { public EvaluatorException(String s) { super(s); } }
 442     static EvaluatorException ee(String s) {
 443         throw new EvaluatorException(JSContext.getSourceName() + ":" + JSContext.getLine() + " " + s);
 444     }
 445     static JS.Exn je(String s) {
 446         throw new JS.Exn(JSContext.getSourceName() + ":" + JSContext.getLine() + " " + s);
 447     }
 448
 449
 450     // Markers //////////////////////////////////////////////////////////////////////
 451
 452     public static class CallMarker {
 453         int pc;
 454         JSScope scope;
 455         JSFunction f;
 456         public CallMarker(JSContext cx) { pc = cx.pc + 1; scope = cx.scope; f = cx.f; }
 457     }
 458
 459     public static class CatchMarker { public CatchMarker() { } }
 460     private static CatchMarker catchMarker = new CatchMarker();
 461
 462     public static class LoopMarker {
 463         public int location;
 464         public String label;
 465         public JSScope scope;
 466         public LoopMarker(int location, String label, JSScope scope) {
 467             this.location = location;
 468             this.label = label;
 469             this.scope = scope;
 470         }
 471     }
 472     public static class TryMarker {
 473         public int catchLoc;
 474         public int finallyLoc;
 475         public JSScope scope;
 476         public TryMarker(int catchLoc, int finallyLoc, JSScope scope) {
 477             this.catchLoc = catchLoc;
 478             this.finallyLoc = finallyLoc;
 479             this.scope = scope;
 480         }
 481     }
 482     public static class FinallyData {
 483         public int op;
 484         public Object arg;
 485         public FinallyData(int op, Object arg) { this.op = op; this.arg = arg; }
 486         public FinallyData(int op) { this(op,null); }
 487     }
 488 }