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          nest0[depth]=nest[depth]=ptr;
          cl->codes[ptr++]=tokenv;
          cl->codes[ptr++]=0;
          depth++;
          break;
        case OP_ELSE:
          if(!depth) ParseError("Premature end of subpattern\n");
          cl->codes[nest[depth-1]+1]=ptr;
          cl->codes[nest[depth-1]+1]=ptr+1;
          cl->codes[ptr++]=OP_ELSE;
          cl->codes[ptr++]=cl->codes[nest[depth-1]];
          cl->codes[nest[depth-1]]=OP_IF;
          cl->codes[ptr++]=0;
          nest[depth-1]=ptr-2;
          break;
        case OP_THEN:
          if(!depth) ParseError("Premature end of subpattern\n");
          cl->codes[nest[--depth]+1]=ptr;
          cl->codes[ptr++]=OP_THEN;
          break;
        case OP_AGAIN:

      break;
    case OP_TRACE:
      if(main_options['t']) {
        printf("ptr=%d cpi=%d x=%d y=%d dir=%d obj=%lu ",ptr,cpi,x,y,d,(long)n);
        printf("[ptr=%d x=%d y=%d dir=%d]\n",cp[cpi].ptr,cp[cpi].x,cp[cpi].y,cp[cpi].dir);
      }
      break;
    default:
      fprintf(stderr,"Unrecognized opcode 0x%04X at 0x%04X in pattern\n",code[ptr-1],ptr-1);
    default: Throw("Unimplemented opcode in pattern");
      Throw("Internal error: Unimplemented opcode in pattern");
  }
  goto again;
  fail:
  if(!all) {
    if(vstackptr<cp->depth) Throw("Stack underflow in pattern matching");
    vstackptr=cp[cpi].depth;
  }